Ventilatory responses at peak exercise in endurance-trained obese adults.

PubMed

Lorenzo, Santiago; Babb, Tony G

2013-10-01

Alterations in respiratory mechanics predispose healthy obese individuals to low lung volume breathing, which places them at risk of developing expiratory flow limitation (EFL). The high ventilatory demand in endurance-trained obese adults further increases their risk of developing EFL and increases their work of breathing. The objective of this study was to investigate the prevalence and magnitude of EFL in fit obese (FO) adults via measurements of breathing mechanics and ventilatory dynamics during exercise. Ten (seven women and three men) FO (mean ± SD, 38 ± 5 years, 38% ± 5% body fat) and 10 (seven women and three men) control obese (CO) (38 ± 5 years, 39% ± 5% body fat) subjects underwent hydrostatic weighing, pulmonary function testing, cycle exercise testing, and the determination of the oxygen cost of breathing during eucapnic voluntary hyperpnea. There were no differences in functional residual capacity (43% ± 6% vs 40% ± 9% total lung capacity [TLC]), residual volume (21% ± 4% vs 21% ± 4% TLC), or FVC (111% ± 13% vs 104% ± 15% predicted) between FO and CO subjects, respectively. FO subjects had higher FEV1 (111% ± 13% vs 99% ± 11% predicted), TLC (106% ± 14% vs 94% ± 7% predicted), peak expiratory flow (123% ± 14% vs 106% ± 13% predicted), and maximal voluntary ventilation (128% ± 15% vs 106% ± 13% predicted) than did CO subjects. Peak oxygen uptake (129% ± 16% vs 86% ± 15% predicted), minute ventilation (128 ± 35 L/min vs 92 ± 25 L/min), and work rate (229 ± 54 W vs 166 ± 55 W) were higher in FO subjects. Mean inspiratory (4.65 ± 1.09 L/s vs 3.06 ± 1.21 L/s) and expiratory (4.15 ± 0.95 L/s vs 2.98 ± 0.76 L/s) flows were greater in FO subjects, which yielded a greater breathing frequency (51 ± 8 breaths/min vs 41 ± 10 breaths/min) at peak exercise in FO subjects. Mechanical ventilatory constraints in FO subjects were similar to those in CO subjects despite the greater ventilatory demand in FO subjects. FO individuals achieve high ventilations by increasing breathing frequency, matching the elevated metabolic demand associated with high fitness. They do this without developing meaningful ventilatory constraints. Therefore, endurance-trained obese individuals with higher lung function are not limited by breathing mechanics during peak exercise, which may allow healthy obese adults to participate in vigorous exercise training.

Methods for Measuring Lung Volumes: Is There a Better One?

PubMed

Tantucci, Claudio; Bottone, Damiano; Borghesi, Andrea; Guerini, Michele; Quadri, Federico; Pini, Laura

2016-01-01

Accurate measurement of lung volumes is of paramount importance to establish the presence of ventilatory defects and give insights for diagnostic and/or therapeutic purposes. It was the aim of this study to measure lung volumes in subjects with respiratory disorders and in normal controls by 3 different techniques (plethysmographic, dilutional and radiographic methods), in an attempt to clarify the role of each of them in performing such a task, without any presumptive 'a priori' superiority of one method above others. Patients andMethods: In different groups of subjects with obstructive and restrictive ventilatory defects and in a normal control group, total lung capacity, functional residual capacity (FRC) and residual volume were measured by body plethysmography, multi-breath helium (He) dilution and radiographic CT scan method with spirometric gating. The 3 methods gave comparable results in normal subjects and in patients with a restrictive defect. In patients with an obstructive defect, CT scan and plethysmography showed similar lung volumes, while on average significantly lower lung volumes were obtained with the He dilution technique. Taking into account that the He dilution technique does primarily measure FRC during tidal breathing, our data suggest that in some patients with an obstructive defect, a number of small airways can be functionally closed at end-expiratory lung volume, preventing He to reach the lung regions subserved by these airways. In all circumstances, both CT scan with spirometric gating and plethysmographic methods provide similar values of lung volumes. In contrast, the He dilution method can measure lower lung volumes in some patients with chronic airflow obstruction. © 2016 S. Karger AG, Basel.

Association between angiotensin-converting enzyme gene polymorphisms and exercise performance in patients with COPD.

PubMed

Zhang, Xiaolei; Wang, Chen; Dai, Huaping; Lin, Yingxiang; Zhang, Jun

2008-09-01

Recent studies have shown that polymorphisms of the angiotensin-converting enzyme (ACE) gene are closely associated with pulmonary disorders. The ACE gene is involved in the regulation of inflammatory reactions to lung injury, respiratory drive, erythropoiesis and tissue oxygenation. The hypothesis for this study was that the ACE gene may be associated with the ventilatory response to exercise and the aerobic work efficiency of skeletal muscle in patients with COPD. Sixty-one Chinese Han COPD patients and 57 healthy control subjects performed incremental cardiopulmonary exercise testing on a cycle ergometer. ACE genotypes were determined using PCR amplification. Resting lung function and blood gas index were not significantly different among the three ACE genotype COPD groups. Similarly, there were no significant differences in AT, maximal O(2) uptake, maximal O(2) pulse, maximal dyspnoea index, ventilatory response (DeltaVE/DeltaVCO(2)), O(2) cost of ventilation (VO(2)/W/VE), end-tidal partial pressure of carbon dioxide at maximal exercise and maximal SaO(2) among the three ACE genotype COPD patients. Maximal work load and aerobic work efficiency were higher in the COPD group with the II genotype than in those with the ID or DD genotype. There were no significant differences in resting lung function and cardiopulmonary exercise testing parameters among the three ACE genotype control groups. The ACE gene may be involved in the regulation of skeletal muscle aerobic work efficiency, but is not associated with the ventilatory responses to exercise in COPD patients.

Static inflation attenuates ischemia/reperfusion injury in an isolated rat lung in situ.

PubMed

Kao, Shang Jyh; Wang, David; Yeh, Diana Yu-Wung; Hsu, Kang; Hsu, Yung Hsiang; Chen, Hsing I

2004-08-01

Ischemia (I)/reperfusion (R) lung injury is an important clinical issue in lung transplantation. In the present study, we observed the effects of lung static inflation, different perfusates, and ventilatory gas with nitrogen or oxygen on the I/R-induced pulmonary damage. A total of 96 male Sprague-Dawley rats were used. The lung was isolated in situ. In an isolated lung, the capillary filtration coefficient (Kfc), lung weight gain (LWG), lung weight (LW)/body weight (BW) ratio, and protein concentration in BAL fluid (PCBAL) were measured or calculated to evaluate the degree of lung injury. Histologic examinations with hematoxylin-eosin staining were performed. I/R caused lung injury, as reflected by increases in Kfc, LWG, LW/BW, and PCBAL. The histopathologic picture revealed the presence of hyaline membrane formation and the infiltration of inflammatory cells. These values were significantly attenuated by static lung inflation. The I/R lung damage appeared to be less in the lung perfused with whole blood than in the lung perfused with an isotonic solution. Therapy with ventilatory air (ie, nitrogen or oxygen) did not alter the I/R lung damage. The data suggest that lung inflation is protective to I/R injury, irrespective of the type of ventilatory air used for treatment. The preservation of the lung for transplantation is better kept at a static inflation state and perfused with whole blood instead of an isotonic physiologic solution.

Ventilatory parameters and maximal respiratory pressure changes with age in Duchenne muscular dystrophy patients.

PubMed

Gayraud, Jerome; Ramonatxo, Michele; Rivier, François; Humberclaude, Véronique; Petrof, Basil; Matecki, Stefan

2010-06-01

The aim of this longitudinal study was to precise, in children with Duchenne muscular dystrophy, the respective functional interest of ventilatory parameters (Vital capacity, total lung capacity and forced expiratory volume in one second [FEV(1)]) in comparison to maximal inspiratory pressure (Pimax) during growth. In ten boys the mean age of 9.1 +/- 1 years) to mean age of 16 +/- 1.4 years followed over a period of 7 years, we found that: (1) ventilatory parameters expressed in percentage of predicted value, after a normal ascending phase, start to decrease between 11 and 12 years, (2) Pimax presented only a decreasing phase since the beginning of the study and thus was already at 67% of predicted value at 12 years while ventilatory parameters was still normal, (3) after 12 years the mean slopes of decrease per year of vital capacity and FEV1 were higher (10.7 and 10.4%) than that of Pimax (6.9%), (4) at 15 years mean values of vital capacity and FEV1 (53.3 and 49.5% of predicted values) was simlar to that of Pimax (48.3%). In conclusion, if at early stages of the disease, Pimax is a more reliable index of respiratory impaiment than ventilatory parameters, the follow-up of ventilatory parameters, when they start to decrease, is a better indicator of disease progression and, at advanced stages they provided same information about the functional impact of disease.

Ventilatory Dysfunction in Parkinson’s Disease

PubMed Central

Baille, Guillaume; De Jesus, Anna Maria; Perez, Thierry; Devos, David; Dujardin, Kathy; Charley, Christelle Monaca; Defebvre, Luc; Moreau, Caroline

2016-01-01

In contrast to some other neurodegenerative diseases, little is known about ventilatory dysfunction in Parkinson’s disease (PD). To assess the spectrum of ventilation disorders in PD, we searched for and reviewed studies of dyspnea, lung volumes, respiratory muscle function, sleep breathing disorders and the response to hypoxemia in PD. Among the studies, we identified some limitations: (i) small study populations (mainly composed of patients with advanced PD), (ii) the absence of long-term follow-up and (iii) the absence of functional evaluations under “off-drug” conditions. Although there are many reports of abnormal spirometry data in PD (mainly related to impairment of the inspiratory muscles), little is known about hypoventilation in PD. We conclude that ventilatory dysfunction in PD has been poorly studied and little is known about its frequency and clinical relevance. Hence, there is a need to characterize the different phenotypes of ventilation disorders in PD, study their relationships with disease progression and assess their prognostic value. PMID:27314755

Relationships (II) of International Classification of High-resolution Computed Tomography for Occupational and Environmental Respiratory Diseases with ventilatory functions indices for parenchymal abnormalities.

PubMed

Tamura, Taro; Suganuma, Narufumi; Hering, Kurt G; Vehmas, Tapio; Itoh, Harumi; Akira, Masanori; Takashima, Yoshihiro; Hirano, Harukazu; Kusaka, Yukinori

2015-01-01

The International Classification of High-Resolution Computed Tomography (HRCT) for Occupational and Environmental Respiratory Diseases (ICOERD) is used to screen and diagnose respiratory illnesses. Using univariate and multivariate analysis, we investigated the relationship between subject characteristics and parenchymal abnormalities according to ICOERD, and the results of ventilatory function tests (VFT). Thirty-five patients with and 27 controls without mineral-dust exposure underwent VFT and HRCT. We recorded all subjects' occupational history for mineral dust exposure and smoking history. Experts independently assessed HRCT using the ICOERD parenchymal abnormalities (Items) grades for well-defined rounded opacities (RO), linear and/or irregular opacities (IR), and emphysema (EM). High-resolution computed tomography showed that 11 patients had RO; 15 patients, IR; and 19 patients, EM. According to the multiple regression model, age and height had significant associations with many indices ventilatory functions such as vital capacity, forced vital capacity, and forced expiratory volume in 1 s (FEV1). The EM summed grades on the upper, middle, and lower zones of the right and left lungs also had significant associations with FEV1 and the maximum mid-expiratory flow rate. The results suggest the ICOERD notation is adequate based on the good and significant multiple regression modeling of ventilatory function with the EM summed grades.

Haemodynamics, dyspnoea, and pulmonary reserve in heart failure with preserved ejection fraction.

PubMed

Obokata, Masaru; Olson, Thomas P; Reddy, Yogesh N V; Melenovsky, Vojtech; Kane, Garvan C; Borlaug, Barry A

2018-05-19

Increases in left ventricular filling pressure are a fundamental haemodynamic abnormality in heart failure with preserved ejection fraction (HFpEF). However, very little is known regarding how elevated filling pressures cause pulmonary abnormalities or symptoms of dyspnoea. We sought to determine the relationships between simultaneously measured central haemodynamics, symptoms, and lung ventilatory and gas exchange abnormalities during exercise in HFpEF. Subjects with invasively-proven HFpEF (n = 50) and non-cardiac causes of dyspnoea (controls, n = 24) underwent cardiac catheterization at rest and during exercise with simultaneous expired gas analysis. During submaximal (20 W) exercise, subjects with HFpEF displayed higher pulmonary capillary wedge pressures (PCWP) and pulmonary artery pressures, higher Borg perceived dyspnoea scores, and increased ventilatory drive and respiratory rate. At peak exercise, ventilation reserve was reduced in HFpEF compared with controls, with greater dead space ventilation (higher VD/VT). Increasing exercise PCWP was directly correlated with higher perceived dyspnoea scores, lower peak exercise capacity, greater ventilatory drive, worse New York Heart Association (NYHA) functional class, and impaired pulmonary ventilation reserve. This study provides the first evidence linking altered exercise haemodynamics to pulmonary abnormalities and symptoms of dyspnoea in patients with HFpEF. Further study is required to identify the mechanisms by which haemodynamic derangements affect lung function and symptoms and to test novel therapies targeting exercise haemodynamics in HFpEF.

Weight Gain after Lung Reduction Surgery Is Related to Improved Lung Function and Ventilatory Efficiency

PubMed Central

Kretschman, Dana M.; Sternberg, Alice L.; DeCamp, Malcolm M.; Criner, Gerard J.

2012-01-01

Rationale: Lung volume reduction surgery (LVRS) is associated with weight gain in some patients, but the group that gains weight after LVRS and the mechanisms underlying this phenomenon have not been well characterized. Objectives: To describe the weight change profiles of LVRS patients enrolled in the National Emphysema Treatment Trial (NETT) and to correlate alterations in lung physiological parameters with changes in weight. Methods: We divided 1,077 non–high-risk patients in the NETT into groups according to baseline body mass index (BMI): underweight (<21 kg/m2), normal weight (21–25 kg/m2), overweight (25–30 kg/m2), and obese (>30 kg/m2). We compared BMI groups and LVRS and medical groups within each BMI stratum with respect to baseline characteristics and percent change in BMI (%ΔBMI) from baseline. We examined patients with (ΔBMI ≥ 5%) and without (ΔBMI < 5%) significant weight gain at 6 months and assessed changes in lung function and ventilatory efficiency (V̇e/V̇co2). Measurements and Main Results: The percent change in BMI was greater in the LVRS arm than in the medical arm in the underweight and normal weight groups at all follow-up time points, and at 12 and 24 months in the overweight group. In the LVRS group, patients with ΔBMI ≥ 5% at 6 months had greater improvements in FEV1 (11.53 ± 9.31 vs. 6.58 ± 8.68%; P < 0.0001), FVC (17.51 ± 15.20 vs. 7.55 ± 14.88%; P < 0.0001), residual volume (–66.20 ± 40.26 vs. –47.06 ± 39.87%; P < 0.0001), 6-minute walk distance (38.70 ± 69.57 vs. 7.57 ± 73.37 m; P < 0.0001), maximal expiratory pressures (12.73 ± 49.08 vs. 3.54 ± 32.22; P = 0.0205), and V̇e/V̇co2 (–1.58 ± 6.20 vs. 0.22 ± 8.20; P = 0.0306) at 6 months than patients with ΔBMI < 5% at 6 months. Conclusions: LVRS leads to weight gain in nonobese patients, which is associated with improvement in lung function, exercise capacity, respiratory muscle strength, and ventilatory efficiency. These physiological changes may be partially responsible for weight gain in patients who undergo LVRS. PMID:22878279

Weight gain after lung reduction surgery is related to improved lung function and ventilatory efficiency.

PubMed

Kim, Victor; Kretschman, Dana M; Sternberg, Alice L; DeCamp, Malcolm M; Criner, Gerard J

2012-12-01

Lung volume reduction surgery (LVRS) is associated with weight gain in some patients, but the group that gains weight after LVRS and the mechanisms underlying this phenomenon have not been well characterized. To describe the weight change profiles of LVRS patients enrolled in the National Emphysema Treatment Trial (NETT) and to correlate alterations in lung physiological parameters with changes in weight. We divided 1,077 non-high-risk patients in the NETT into groups according to baseline body mass index (BMI): underweight (<21 kg/m(2)), normal weight (21-25 kg/m(2)), overweight (25-30 kg/m(2)), and obese (>30 kg/m(2)). We compared BMI groups and LVRS and medical groups within each BMI stratum with respect to baseline characteristics and percent change in BMI (%ΔBMI) from baseline. We examined patients with (ΔBMI ≥ 5%) and without (ΔBMI < 5%) significant weight gain at 6 months and assessed changes in lung function and ventilatory efficiency (Ve/Vco(2)). The percent change in BMI was greater in the LVRS arm than in the medical arm in the underweight and normal weight groups at all follow-up time points, and at 12 and 24 months in the overweight group. In the LVRS group, patients with ΔBMI ≥ 5% at 6 months had greater improvements in FEV(1) (11.53 ± 9.31 vs. 6.58 ± 8.68%; P < 0.0001), FVC (17.51 ± 15.20 vs. 7.55 ± 14.88%; P < 0.0001), residual volume (-66.20 ± 40.26 vs. -47.06 ± 39.87%; P < 0.0001), 6-minute walk distance (38.70 ± 69.57 vs. 7.57 ± 73.37 m; P < 0.0001), maximal expiratory pressures (12.73 ± 49.08 vs. 3.54 ± 32.22; P = 0.0205), and Ve/Vco(2) (-1.58 ± 6.20 vs. 0.22 ± 8.20; P = 0.0306) at 6 months than patients with ΔBMI < 5% at 6 months. LVRS leads to weight gain in nonobese patients, which is associated with improvement in lung function, exercise capacity, respiratory muscle strength, and ventilatory efficiency. These physiological changes may be partially responsible for weight gain in patients who undergo LVRS.

The physiological basis and clinical significance of lung volume measurements.

PubMed

Lutfi, Mohamed Faisal

2017-01-01

From a physiological standpoint, the lung volumes are either dynamic or static. Both subclasses are measured at different degrees of inspiration or expiration; however, dynamic lung volumes are characteristically dependent on the rate of air flow. The static lung volumes/capacities are further subdivided into four standard volumes (tidal, inspiratory reserve, expiratory reserve, and residual volumes) and four standard capacities (inspiratory, functional residual, vital and total lung capacities). The dynamic lung volumes are mostly derived from vital capacity. While dynamic lung volumes are essential for diagnosis and follow up of obstructive lung diseases, static lung volumes are equally important for evaluation of obstructive as well as restrictive ventilatory defects. This review intends to update the reader with the physiological basis, clinical significance and interpretative approaches of the standard static lung volumes and capacities.

Multicenter comparative study of conventional mechanical gas ventilation to tidal liquid ventilation in oleic acid injured sheep.

PubMed

Wolfson, Marla R; Hirschl, Ronald B; Jackson, J Craig; Gauvin, France; Foley, David S; Lamm, Wayne J E; Gaughan, John; Shaffer, Thomas H

2008-01-01

We performed a multicenter study to test the hypothesis that tidal liquid ventilation (TLV) would improve cardiopulmonary, lung histomorphological, and inflammatory profiles compared with conventional mechanical gas ventilation (CMV). Sheep were studied using the same volume-controlled, pressure-limited ventilator systems, protocols, and treatment strategies in three independent laboratories. Following baseline measurements, oleic acid lung injury was induced and animals were randomized to 4 hours of CMV or TLV targeted to "best PaO2" and PaCO2 35 to 60 mm Hg. The following were significantly higher (p < 0.01) during TLV than CMV: PaO2, venous oxygen saturation, respiratory compliance, cardiac output, stroke volume, oxygen delivery, ventilatory efficiency index; alveolar area, lung % gas exchange space, and expansion index. The following were lower (p < 0.01) during TLV compared with CMV: inspiratory and expiratory pause pressures, mean airway pressure, minute ventilation, physiologic shunt, plasma lactate, lung interleukin-6, interleukin-8, myeloperoxidase, and composite total injury score. No significant laboratories by treatment group interactions were found. In summary, TLV resulted in improved cardiopulmonary physiology at lower ventilatory requirements with more favorable histological and inflammatory profiles than CMV. As such, TLV offers a feasible ventilatory alternative as a lung protective strategy in this model of acute lung injury.

Ventilatory mechanics and the effects of water depth on breathing pattern in the aquatic caecilian Typhlonectes natans.

PubMed

Prabha, K C; Bernard, D G; Gardner, M; Smatresk, N J

2000-01-01

The breathing pattern in the aquatic caecilian Typhlonectes natans was investigated by recording airflow via a pneumotachograph under unrestrained normal physiological conditions. Ventilatory mechanics were assessed using airflow and pressure measurements from the buccal cavity and trachea. The breathing pattern consisted of an expiratory phase followed by a series of 10-15 small buccal pumps to inflate the lung, succeeded by a long non-ventilatory period. T. natans separate the expiratory and inspiratory gases in the buccal cavity and take several inspiratory pumps, distinguishing their breathing pattern from that of sarcopterygians. Hydrostatic pressure assisted exhalation. The tracheal pressure was greater than the water pressure at that depth, suggesting that pleuroperitoneal pressure as well as axial or pulmonary smooth muscles may have contributed to the process of exhalation. The frequency of lung ventilation was 6.33+/-0.84 breaths h(-)(1), and ventilation occurred via the nares. Compared with other amphibians, this low ventilatory frequency suggests that T. natans may have acquired very efficient pulmonary respiration as an adaptation for survival in their seasonally fluctuating natural habitat. Their respiratory pathway is quite unique, with the trachea separated into anterior, central and posterior regions. The anterior region serves as an air channel, the central region is attached to the tracheal lung, and the posterior region consists of a bifurcated air channel leading to the left and right posterior lungs. The lungs are narrow, elongated, profusely vascularized and compartmentalized. The posterior lungs extend to approximately two-thirds of the body length. On the basis of their breathing pattern, it appears that caecilians are phylogenetically derived from two-stroke breathers.

Prevalence of abnormal findings when adopting new national and international Global Lung Function Initiative reference values for spirometry in the Finnish general population

PubMed Central

Kainu, Annette; Lindqvist, Ari; Sovijärvi, Anssi R. A.

2016-01-01

Background New Finnish (Kainu2015) and international Global Lung Function Initiative (GLI2012) reference values for spirometry were recently published. The aim of this study is to compare the interpretative consequences of adopting these new reference values with older, currently used Finnish reference values (Viljanen1982) in the general population of native Finns. Methods Two Finnish general population samples including 1,328 adults (45% males) aged 21–74 years were evaluated. Airway obstruction was defined as a reduced ratio of forced expiratory volume in one second (FEV1)/forced vital capacity (FVC), possible restrictive pattern as reduced FVC, and decreased ventilatory capacity as reduced FEV1 below their respective 2.5th percentiles. The severity gradings of reduced lung function were also compared. Results Using the Kainu2015 reference values, the prevalence of airway obstruction in the population was 5.6%; using GLI2012 it was 4.0% and with Viljanen1982 it was 13.0%. Possible restrictive pattern was found in 4.2% using the Kainu2015 values, in 2.0% with GLI2012, and 7.9% with the Viljanen1982 values. The prevalence of decreased ventilatory capacity was 6.8, 4.0, and 13.3% with the Kainu2015, GLI2012 and Viljanen1982 values, respectively. Conclusions The application of the GLI2012 reference values underestimates the prevalence of abnormal spirometric findings in native Finns. The adoption of the Kainu2015 reference values reduces the prevalences of airways obstruction, decreased ventilatory capacity, and restrictive impairment by approximately 50%. Changing from the 2.5th percentile, the previously used lower limit of normal, to the 5th percentile recommended by the American Thoracic Society/European Respiratory Society will not increase the prevalence of abnormal findings in the implementation of spirometry reference values. PMID:27608270

History of Mechanical Ventilation. From Vesalius to Ventilator-induced Lung Injury.

PubMed

Slutsky, Arthur S

2015-05-15

Mechanical ventilation is a life-saving therapy that catalyzed the development of modern intensive care units. The origins of modern mechanical ventilation can be traced back about five centuries to the seminal work of Andreas Vesalius. This article is a short history of mechanical ventilation, tracing its origins over the centuries to the present day. One of the great advances in ventilatory support over the past few decades has been the development of lung-protective ventilatory strategies, based on our understanding of the iatrogenic consequences of mechanical ventilation such as ventilator-induced lung injury. These strategies have markedly improved clinical outcomes in patients with respiratory failure.

Mechanical ventilation and thoracic artificial lung assistance during mechanical circulatory support with PUCA pump: in silico study.

PubMed

De Lazzari, Claudio; Genuini, Igino; Quatember, Bernhard; Fedele, Francesco

2014-02-01

Patients assisted with left ventricular assist device (LVAD) may require prolonged mechanical ventilatory assistance secondary to postoperative respiratory failure. The goal of this work is the study of the interdependent effects LVAD like pulsatile catheter (PUCA) pump and mechanical ventilatory support or thoracic artificial lung (TAL), by the hemodynamic point of view, using a numerical simulator of the human cardiovascular system. In the simulator, different circulatory sections are described using lumped parameter models. Lumped parameter models have been designed to describe the hydrodynamic behavior of both PUCA pump and thoracic artificial lung. Ventricular behavior atrial and septum functions were reproduced using variable elastance model. Starting from simulated pathological conditions we studied the effects produced on some hemodynamic variables by simultaneous PUCA pump, thoracic artificial lung or mechanical ventilation assistance. Thoracic artificial lung was applied in parallel or in hybrid mode. The effects of mechanical ventilation have been simulated by changing mean intrathoracic pressure value from -4 mmHg to +5 mmHg. The hemodynamic variables observed during the simulations, in different assisted conditions, were: left and right ventricular end systolic (diastolic) volume, systolic/diastolic aortic pressure, mean pulmonary arterial pressure, left and right mean atrial pressure, mean systemic venous pressure and the total blood flow. Results show that the application of PUCA (without mechanical ventilatory assistance) increases the total blood flow, reduces the left ventricular end systolic volume and increases the diastolic aortic pressure. Parallel TAL assistance increases the right ventricular end diastolic (systolic) volume reduction both when PUCA is switched "ON" and both when PUCA is switched "OFF". By switching "OFF" the PUCA pump, it seems that parallel thoracic artificial lung assistance produces a greater cardiac output (respect to hybrid TAL assistance). Results concerning PUCA and TAL interaction produced by simulations cannot be compared with "in vivo" results since they are not presented in literature. But results concerning the effects produced by LVAD and mechanical ventilation have a trend consistent with those presented in literature. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Breathing mechanics during exercise with added dead space reflect mechanisms of ventilatory control.

PubMed

Wood, Helen E; Mitchell, Gordon S; Babb, Tony G

2009-09-30

Small increases in external dead space (V(D)) augment the exercise ventilatory response via a neural mechanism known as short-term modulation (STM). We hypothesized that breathing mechanics would differ during exercise, increased V(D) and STM. Men were studied at rest and during cycle exercise (10-50W) without (Control) and with added V(D) (200-600ml). With added V(D), V(T) increased via increased end-inspiratory lung volume (EILV), with no change in end-expiratory lung volume (EELV), indicating recruitment of inspiratory muscles only. With exercise, V(T) increased via both decreased EELV and increased EILV, indicating recruitment of both expiratory and inspiratory muscles. A significant interaction between the effects of exercise and V(D) on mean inspiratory flow indicated that the augmented exercise ventilatory response with added V(D) (i.e. STM) resulted from increased drive to the inspiratory muscles. These results reveal different patterns of respiratory muscle recruitment among experimental conditions. Hence, we conclude that fundamental differences exist in the neural control of ventilatory responses during exercise, increased V(D) and STM.

Association between the Type of Workplace and Lung Function in Copper Miners

PubMed Central

Gruszczyński, Leszek; Wojakowska, Anna; Ścieszka, Marek; Turczyn, Barbara; Schmidt, Edward

2016-01-01

The aim of the analysis was to retrospectively assess changes in lung function in copper miners depending on the type of workplace. In the groups of 225 operators, 188 welders, and 475 representatives of other jobs, spirometry was performed at the start of employment and subsequently after 10, 20, and 25 years of work. Spirometry Longitudinal Data Analysis software was used to estimate changes in group means for FEV1 and FVC. Multiple linear regression analysis was used to assess an association between workplace and lung function. Lung function assessed on the basis of calculation of longitudinal FEV1 (FVC) decline was similar in all studied groups. However, multiple linear regression model used in cross-sectional analysis revealed an association between workplace and lung function. In the group of welders, FEF75 was lower in comparison to operators and other miners as early as after 10 years of work. Simultaneously, in smoking welders, the FEV1/FVC ratio was lower than in nonsmokers (p < 0,05). The interactions between type of workplace and smoking (p < 0,05) in their effect on FVC, FEV1, PEF, and FEF50 were shown. Among underground working copper miners, the group of smoking welders is especially threatened by impairment of lung ventilatory function. PMID:27274987

A historical perspective on ventilator management.

PubMed

Shapiro, B A

1994-02-01

Paralysis via neuromuscular blockade in ICU patients requires mechanical ventilation. This review historically addresses the technological advances and scientific information upon which ventilatory management concepts are based, with special emphasis on the influence such concepts have had on the use of neuromuscular blocking agents. Specific reference is made to the scientific information and technological advances leading to the newer concepts of ventilatory management. Information from > 100 major studies in the peer-reviewed medical literature, along with the author's 25 yrs of clinical experience and academic involvement in acute respiratory care is presented. Nomenclature related to ventilatory management is specifically defined and consistently utilized to present and interpret the data. Pre-1970 ventilatory management is traced from the clinically unacceptable pressure-limited devices to the reliable performance of volume-limited ventilators. The scientific data and rationale that led to the concept of relatively large tidal volume delivery are reviewed in the light of today's concerns regarding alveolar overdistention, control-mode dyssynchrony, and auto-positive end-expiratory pressure. Also presented are the post-1970 scientific rationales for continuous positive airway pressure/positive end-expiratory pressure therapy, avoidance of alveolar hyperxia, and partial ventilatory support techniques (intermittent mandatory ventilation/synchronized intermittent mandatory ventilation). The development of pressure-support devices is discussed and the capability of pressure-control techniques is presented. The rationale for more recent concepts of total ventilatory support to avoid ventilator-induced lung injury is presented. The traditional techniques utilizing volume-preset ventilators with relatively large tidal volumes remain valid and desirable for the vast majority of patients requiring mechanical ventilation. Neuromuscular blockade is best avoided in these patients. However, adequate analgesia, amnesia, and sedation are required. For patients with severe lung disease, alveolar overdistention and hyperoxia should be avoided and may be best accomplished by total ventilatory support techniques, such as pressure control. Total ventilatory support requires neuromuscular blockade and may not provide eucapnic ventilation.

Effects of a helium/oxygen mixture on individuals' lung function and metabolic cost during submaximal exercise for participants with obstructive lung diseases.

PubMed

Häussermann, Sabine; Schulze, Anja; Katz, Ira M; Martin, Andrew R; Herpich, Christiane; Hunger, Theresa; Texereau, Joëlle

2015-01-01

Helium/oxygen therapies have been studied as a means to reduce the symptoms of obstructive lung diseases with inconclusive results in clinical trials. To better understand this variability in results, an exploratory physiological study was performed comparing the effects of helium/oxygen mixture (78%/22%) to that of medical air. The gas mixtures were administered to healthy, asthmatic, and chronic obstructive pulmonary disease (COPD) participants, both moderate and severe (6 participants in each disease group, a total of 30); at rest and during submaximal cycling exercise with equivalent work rates. Measurements of ventilatory parameters, forced spirometry, and ergospirometry were obtained. There was no statistical difference in ventilatory and cardiac responses to breathing helium/oxygen during submaximal exercise. For asthmatics, but not for the COPD participants, there was a statistically significant benefit in reduced metabolic cost, determined through measurement of oxygen uptake, for the same exercise work rate. However, the individual data show that there were a mixture of responders and nonresponders to helium/oxygen in all of the groups. The inconsistent response to helium/oxygen between individuals is perhaps the key drawback to the more effective and widespread use of helium/oxygen to increase exercise capacity and for other therapeutic applications.

[Comparative study of respiratory exchanging surfaces in birds and mammals].

PubMed

Jammes, Y

1975-01-01

Anatomical studies of the respiratory apparatus of birds show evidences for a gas exchanging tubular system (parabronchi and air capillaries); these exchanging structures are entirely dissociated from the ventilatory drive acting on the air sacs. A "cross-current" gas exchanging system (perpendicular disposition of air and blood capillaries) allow a good wash-out of carbon dioxide (PaCO2 lower than PECO2). The great efficiency of this lung is allowed by its very large diffusive surface (ASa) and by the high values of lung specific oxygen diffusing capacity (DO2/ASa) and of O2 extraction coefficient in inspired air. The ventilatory pattern of birds is characterized by a greater tidal volume and a smaller respiratory frequency than in mammals of same weight. Respiratory centers of birds receive afferences from lung stretch receptors, CO2-sensitive lung receptors and arterial chemoreceptors.

Rationale and study design for an individualised perioperative open-lung ventilatory strategy with a high versus conventional inspiratory oxygen fraction (iPROVE-O2) and its effects on surgical site infection: study protocol for a randomised controlled trial.

PubMed

Ferrando, Carlos; Soro, Marina; Unzueta, Carmen; Canet, Jaume; Tusman, Gerardo; Suarez-Sipmann, Fernando; Librero, Julian; Peiró, Salvador; Pozo, Natividad; Delgado, Carlos; Ibáñez, Maite; Aldecoa, César; Garutti, Ignacio; Pestaña, David; Rodríguez, Aurelio; García Del Valle, Santiago; Diaz-Cambronero, Oscar; Balust, Jaume; Redondo, Francisco Javier; De La Matta, Manuel; Gallego, Lucía; Granell, Manuel; Martínez, Pascual; Pérez, Ana; Leal, Sonsoles; Alday, Kike; García, Pablo; Monedero, Pablo; Gonzalez, Rafael; Mazzinari, Guido; Aguilar, Gerardo; Villar, Jesús; Belda, Francisco Javier

2017-07-31

Surgical site infection (SSI) is a serious postoperative complication that increases morbidity and healthcare costs. SSIs tend to increase as the partial pressure of tissue oxygen decreases: previous trials have focused on trying to reduce them by comparing high versus conventional inspiratory oxygen fractions (FIO 2 ) in the perioperative period but did not use a protocolised ventilatory strategy. The open-lung ventilatory approach restores functional lung volume and improves gas exchange, and therefore it may increase the partial pressure of tissue oxygen for a given FIO 2 . The trial presented here aims to compare the efficacy of high versus conventional FIO 2 in reducing the overall incidence of SSIs in patients by implementing a protocolised and individualised global approach to perioperative open-lung ventilation. This is a comparative, prospective, multicentre, randomised and controlled two-arm trial that will include 756 patients scheduled for abdominal surgery. The patients will be randomised into two groups: (1) a high FIO 2 group (80% oxygen; FIO 2 of 0.80) and (2) a conventional FIO 2 group (30% oxygen; FIO 2 of 0.30). Each group will be assessed intra- and postoperatively. The primary outcome is the appearance of postoperative SSI complications. Secondary outcomes are the appearance of systemic and pulmonary complications. The iPROVE-O2 trial has been approved by the Ethics Review Board at the reference centre (the Hospital Clínico Universitario in Valencia). Informed consent will be obtained from all patients before their participation. If the approach using high FIO 2 during individualised open-lung ventilation decreases SSIs, use of this method will become standard practice for patients scheduled for future abdominal surgery. Publication of the results is anticipated in early 2019. NCT02776046; Pre-results. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Ventilation distribution measured with EIT at varying levels of pressure support and Neurally Adjusted Ventilatory Assist in patients with ALI.

PubMed

Blankman, Paul; Hasan, Djo; van Mourik, Martijn S; Gommers, Diederik

2013-06-01

The purpose of this study was to compare the effect of varying levels of assist during pressure support (PSV) and Neurally Adjusted Ventilatory Assist (NAVA) on the aeration of the dependent and non-dependent lung regions by means of Electrical Impedance Tomography (EIT). We studied ten mechanically ventilated patients with Acute Lung Injury (ALI). Positive-End Expiratory Pressure (PEEP) and PSV levels were both 10 cm H₂O during the initial PSV step. Thereafter, we changed the inspiratory pressure to 15 and 5 cm H₂O during PSV. The electrical activity of the diaphragm (EAdi) during pressure support ten was used to define the initial NAVA gain (100 %). Thereafter, we changed NAVA gain to 150 and 50 %, respectively. After each step the assist level was switched back to PSV 10 cm H₂O or NAVA 100 % to get a new baseline. The EIT registration was performed continuously. Tidal impedance variation significantly decreased during descending PSV levels within patients, whereas not during NAVA. The dorsal-to-ventral impedance distribution, expressed according to the center of gravity index, was lower during PSV compared to NAVA. Ventilation contribution of the dependent lung region was equally in balance with the non-dependent lung region during PSV 5 cm H₂O, NAVA 50 and 100 %. Neurally Adjusted Ventilatory Assist ventilation had a beneficial effect on the ventilation of the dependent lung region and showed less over-assistance compared to PSV in patients with ALI.

TU-CD-BRA-11: Application of Bone Suppression Technique to Inspiratory/expiratory Chest Radiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, R; Sanada, S; Sakuta, K

Purpose: The bone suppression technique based on advanced image processing can suppress the conspicuity of bones on chest radiographs, creating soft tissue images normally obtained by the dual-energy subtraction technique. This study was performed to investigate the usefulness of bone suppression technique in quantitative analysis of pulmonary function in inspiratory/expiratory chest radiography. Methods: Commercial bone suppression image processing software (ClearRead; Riverain Technologies) was applied to paired inspiratory/expiratory chest radiographs of 107 patients (normal, 33; abnormal, 74) to create corresponding bone suppression images. The abnormal subjects had been diagnosed with pulmonary diseases, such as pneumothorax, pneumonia, emphysema, asthma, and lung cancer.more » After recognition of the lung area, the vectors of respiratory displacement were measured in all local lung areas using a cross-correlation technique. The measured displacement in each area was visualized as displacement color maps. The distribution pattern of respiratory displacement was assessed by comparison with the findings of lung scintigraphy. Results: Respiratory displacement of pulmonary markings (soft tissues) was able to be quantified separately from the rib movements on bone suppression images. The resulting displacement map showed a left-right symmetric distribution increasing from the lung apex to the bottom region of the lung in many cases. However, patients with ventilatory impairments showed a nonuniform distribution caused by decreased displacement of pulmonary markings, which were confirmed to correspond to area with ventilatory impairments found on the lung scintigrams. Conclusion: The bone suppression technique was useful for quantitative analysis of respiratory displacement of pulmonary markings without any interruption of the rib shadows. Abnormal areas could be detected as decreased displacement of pulmonary markings. Inspiratory/expiratory chest radiography combined with the bone suppression technique has potential for predicting local lung function on the basis of dynamic analysis of pulmonary markings. This work was partially supported by Nakatani Foundation, Grant-in-aid for Scientific Research (C) of Ministry of Education, Culture, Sports, Science and Technology, JAPAN (Grant number : 24601007), and Nakatani Foundation, Mitsubishi Foundation, and the he Mitani Foundation for Research and Development. Yasushi Kishitani is a staff of TOYO corporation.« less

High-frequency oscillatory ventilation in ALI/ARDS.

PubMed

Ali, Sammy; Ferguson, Niall D

2011-07-01

In the last 2 decades, our goals for mechanical ventilatory support in patients with acute respiratory distress syndrome (ARDS) or acute lung injury (ALI) have changed dramatically. Several randomized controlled trials have built on a substantial body of preclinical work to demonstrate that the way in which we employ mechanical ventilation has an impact on important patient outcomes. Avoiding ventilator-induced lung injury (VILI) is now a major focus when clinicians are considering which ventilatory strategy to employ in patients with ALI/ARDS. Physicians are searching for methods that may further limit VILI, while still achieving adequate gas exchange. Copyright © 2011 Elsevier Inc. All rights reserved.

Propagation prevention: a complementary mechanism for "lung protective" ventilation in acute respiratory distress syndrome.

PubMed

Marini, John J; Gattinoni, Luciano

2008-12-01

To describe the clinical implications of an often neglected mechanism through which localized acute lung injury may be propagated and intensified. Experimental and clinical evidence from the medical literature relevant to the airway propagation hypothesis and its consequences. The diffuse injury that characterizes acute respiratory distress syndrome is often considered a process that begins synchronously throughout the lung, mediated by inhaled or blood-borne noxious agents. Relatively little attention has been paid to possibility that inflammatory lung injury may also begin focally and propagate sequentially via the airway network, proceeding mouth-ward from distal to proximal. Were this true, modifications of ventilatory pattern and position aimed at geographic containment of the injury process could help prevent its generalization and limit disease severity. The purposes of this communication are to call attention to this seldom considered mechanism for extending lung injury that might further justify implementation of low tidal volume/high positive end-expiratory pressure ventilatory strategies for lung protection and to suggest additional therapeutic measures implied by this broadened conceptual paradigm.

Abnormalities in lung volumes and airflow in children with newly diagnosed connective tissue disease.

PubMed

Peradzyńska, Joanna; Krenke, Katarzyna; Szylling, Anna; Kołodziejczyk, Beata; Gazda, Agnieszka; Rutkowska-Sak, Lidia; Kulus, Marek

2016-01-01

Connective tissue diseases (CTDs) of childhood are rare inflammatory disorders, involving various organs and tissues including respiratory system. Pulmonary involvement in patients with CTDs is uncommon but may cause functional impairment. Data on prevalence and type of lung function abnormalities in children with CTDs are scarce. Thus, the aim of this study was to asses pulmonary functional status in children with newly diagnosed CTD and follow the results after two years of the disease course. There were 98 children (mean age: 13 ± 3; 76 girls), treated in Department of Pediatric Rheumatology, Institute of Rheumatology, Warsaw and 80 aged-matched, healthy controls (mean age 12.7 ± 2.4; 50 girls) included into the study. Study procedures included medical history, physical examination, chest radiograph and PFT (spirometry and whole body-plethysmography). Then, the assessment of PFT was performed after 24 months. FEV₁, FEV₁/FVC and MEF50 were significantly lower in CTD as compared to control group, there was no difference in FVC and TLC. The proportion of patients with abnormal lung function was significantly higher in the study group, 41 (42%) vs 9 (11%). 24-months observation didn't reveal progression in lung function impairment. Lung function impairment is relatively common in children with CTDs. Although restrictive ventilatory pattern is considered typical feature of lung involvement in CTDs, airflow limitation could also be an initial abnormality.

Excess Ventilation in Chronic Obstructive Pulmonary Disease-Heart Failure Overlap. Implications for Dyspnea and Exercise Intolerance.

PubMed

Rocha, Alcides; Arbex, Flavio F; Sperandio, Priscilla A; Souza, Aline; Biazzim, Ligia; Mancuso, Frederico; Berton, Danilo C; Hochhegger, Bruno; Alencar, Maria Clara N; Nery, Luiz E; O'Donnell, Denis E; Neder, J Alberto

2017-11-15

An increased ventilatory response to exertional metabolic demand (high [Formula: see text]e/[Formula: see text]co 2 relationship) is a common finding in patients with coexistent chronic obstructive pulmonary disease and heart failure. We aimed to determine the mechanisms underlying high [Formula: see text]e/[Formula: see text]co 2 and its impact on operating lung volumes, dyspnea, and exercise tolerance in these patients. Twenty-two ex-smokers with combined chronic obstructive pulmonary disease and heart failure with reduced left ventricular ejection fraction undertook, after careful treatment optimization, a progressive cycle exercise test with capillary (c) blood gas collection. Regardless of the chosen metric (increased [Formula: see text]e-[Formula: see text]co 2 slope, [Formula: see text]e/[Formula: see text]co 2 nadir, or end-exercise [Formula: see text]e/[Formula: see text]co 2 ), ventilatory inefficiency was closely related to Pc CO 2 (r values from -0.80 to -0.84; P < 0.001) but not dead space/tidal volume ratio. Ten patients consistently maintained exercise Pc CO 2 less than or equal to 35 mm Hg (hypocapnia). These patients had particularly poor ventilatory efficiency compared with patients without hypocapnia (P < 0.05). Despite the lack of between-group differences in spirometry, lung volumes, and left ventricular ejection fraction, patients with hypocapnia had lower resting Pa CO 2 and lung diffusing capacity (P < 0.01). Excessive ventilatory response in this group was associated with higher exertional Pc O 2 . The group with hypocapnia, however, had worse mechanical inspiratory constraints and higher dyspnea scores for a given work rate leading to poorer exercise tolerance compared with their counterparts (P < 0.05). Heightened neural drive promoting a ventilatory response beyond that required to overcome an increased "wasted" ventilation led to hypocapnia and poor exercise ventilatory efficiency in chronic obstructive pulmonary disease-heart failure overlap. Excessive ventilation led to better arterial oxygenation but at the expense of earlier critical mechanical constraints and intolerable dyspnea.

Respiratory symptoms and lung function in furriers.

PubMed

Zuskin, E; Skuric, Z; Kanceljak, B; Pokrajac, D; Schachter, E N; Witek, T J

1988-01-01

Forty women who had been occupationally exposed in the fur coat manufacturing industry were studied. The mean age was 30 years; mean duration of exposure was 14 years. A group of 31 females who did not work in the furrier industry also was included in the study as the control group. A higher prevalence of all chronic respiratory symptoms was found among furriers when compared with controls; these differences were statistically significant for nasal catarrh (p less than 0.05) and sinusitis (p less than 0.01). Among the furriers, the highest prevalence of respiratory symptoms was recorded for chronic cough in 20 workers (50.0%), followed by sinusitis in 12 (30.0%), dyspnea in 10 (25.0%), and nasal catarrh in 8 workers (20.0%). Among the furriers, two (5.0%) had symptoms characteristic of occupational asthma. Most of the symptomatic furriers complained of acute symptoms during their work shifts. Statistically significant mean reductions in lung function over the work shift were recorded in furriers for forced vital capacity (FVC), -4.1%; one-second forced expiratory volume (FEV1), -5.2%; and flow rate at 50% vital capacity (FEF50%), -6.3%. Furriers demonstrated significantly lower mean Monday preshift measurements for FVC and flow rate at 25% (FEF25%) (p less than 0.05) when compared with those predicted. Preshift administration (by spinhaler) of 40 mg disodium cromoglycate in three workers reduced the intensity of acute respiratory symptoms and diminished the reductions in ventilatory capacity over the work shift. Data from six additional male workers demonstrated similar findings for symptoms and lung function. Our data suggest that furriers are at risk of developing both acute and chronic respiratory symptoms as well as ventilatory capacity impairment as a result of occupational exposure.

Brain-lung crosstalk in critical care: how protective mechanical ventilation can affect the brain homeostasis.

PubMed

Mazzeo, A T; Fanelli, V; Mascia, L

2013-03-01

The maintenance of brain homeostasis against multiple internal and external challenges occurring during the acute phase of acute brain injury may be influenced by critical care management, especially in its respiratory, hemodynamic and metabolic components. The occurrence of acute lung injury represents the most frequent extracranial complication after brain injury and deserves special attention in daily practice as optimal ventilatory strategy for patients with acute brain and lung injury are potentially in conflict. Protecting the lung while protecting the brain is thus a new target in the modern neurointensive care. This article discusses the essentials of brain-lung crosstalk and focuses on how mechanical ventilation may exert an active role in the process of maintaining or treatening brain homeostasis after acute brain injury, highlighting the following points: 1) the role of inflammation as common pathomechanism of both acute lung and brain injury; 2) the recognition of ventilatory induced lung injury as determinant of systemic inflammation affecting distal organs, included the brain; 3) the possible implication of protective mechanical ventilation strategy on the patient with an acute brain injury as an undiscovered area of research in both experimental and clinical settings.

Pulmonary functions of narghile smokers compared to cigarette smokers: a case-control study.

PubMed

Ben Saad, Helmi; Khemiss, Mehdi; Nhari, Saida; Ben Essghaier, Mejda; Rouatbi, Sonia

2013-01-01

Studies of the lung function profiles of exclusive narghile smokers (ENS) are few, have some methodological limits, and present contradictory conclusions. The present study aimed to compare the plethysmographic profiles of ENS with age- and height-matched exclusive cigarette smokers (ECS). Males aged 35-60 living in Sousse, Tunisia, who have been smoking narghile exclusively for more than 10 narghile-years (n = 36) or cigarettes exclusively for more than 10 pack-years (n = 106) were recruited to participate in this case-control study. The anthropometric and plethysmographic data were measured according to international recommendations using a body plethysmograph (ZAN 500 Body II, Meβgreräte GmbH, Germany). Large-airway-obstructive-ventilatory-defect (LAOVD) was defined as: first second forced expiratory volume/forced vital capacity (FEV1/FVC) below the lower-limit-of-normal (LLN). Restrictive-ventilatory-defect (RVD) was defined as total lung capacity < LLN. Lung hyperinflation was defined as residual volume > upper-limit-of-normal. Student t-test and χ(2) test were used to compare plethysmographic data and profiles of the two groups. The subjects in the ENS and ECS groups are well matched in age (45±7 vs. 47±5 years) and height (1.73±0.06 vs. 1.72±0.06 m) and used similar quantities of tobacco (36±22 narghile-years vs. 35±19 pack-years). Compared to the ENS group, the ECS group had significantly lower FEV1 (84±12 vs. 60±21%), FVC (90±12 vs. 76±18%), and FEV1/FVC (99±7 vs. 83±17%). The two groups had similar percentages of RVD (31 vs. 36%), while the ECS group had a significantly higher percentage of LAOVD (8 vs. 58%) and lung hyperinflation (36 vs.57%). Chronic exclusive narghile smoking has less adverse effects on pulmonary function tests than chronic exclusive cigarette smoking.

Pulmonary functions of narghile smokers compared to cigarette smokers: a case-control study.

PubMed

Saad, Helmi Ben; Khemiss, Mehdi; Nhari, Saida; Essghaier, Mejda Ben; Rouatbi, Sonia

2013-01-01

Background Studies of the lung function profiles of exclusive narghile smokers (ENS) are few, have some methodological limits, and present contradictory conclusions. The present study aimed to compare the plethysmographic profiles of ENS with age- and height-matched exclusive cigarette smokers (ECS). Methods Males aged 35-60 living in Sousse, Tunisia, who have been smoking narghile exclusively for more than 10 narghile-years (n = 36) or cigarettes exclusively for more than 10 pack-years (n = 106) were recruited to participate in this case-control study. The anthropometric and plethysmographic data were measured according to international recommendations using a body plethysmograph (ZAN 500 Body II, Meβgreräte GmbH, Germany). Large-airway-obstructive-ventilatory-defect (LAOVD) was defined as: first second forced expiratory volume/forced vital capacity (FEV 1 /FVC) below the lower-limit-of-normal (LLN). Restrictive-ventilatory-defect (RVD) was defined as total lung capacity < LLN. Lung hyperinflation was defined as residual volume > upper-limit-of-normal. Student t-test and χ 2 test were used to compare plethysmographic data and profiles of the two groups. Results The subjects in the ENS and ECS groups are well matched in age (45±7 vs. 47±5 years) and height (1.73±0.06 vs. 1.72±0.06 m) and used similar quantities of tobacco (36±22 narghile-years vs. 35±19 pack-years). Compared to the ENS group, the ECS group had significantly lower FEV 1 (84±12 vs. 60±21%), FVC (90±12 vs. 76±18%), and FEV 1 /FVC (99±7 vs. 83±17%). The two groups had similar percentages of RVD (31 vs. 36%), while the ECS group had a significantly higher percentage of LAOVD (8 vs. 58%) and lung hyperinflation (36 vs.57%). Conclusion Chronic exclusive narghile smoking has less adverse effects on pulmonary function tests than chronic exclusive cigarette smoking.

Effect of exercise training on ventilatory efficiency in patients with heart disease: a review.

PubMed

Prado, D M L; Rocco, E A; Silva, A G; Rocco, D F; Pacheco, M T; Furlan, V

2016-06-20

The analysis of ventilatory efficiency in cardiopulmonary exercise testing has proven useful for assessing the presence and severity of cardiorespiratory diseases. During exercise, efficient pulmonary gas exchange is characterized by uniform matching of lung ventilation with perfusion. By contrast, mismatching is marked by inefficient pulmonary gas exchange, requiring increased ventilation for a given CO2 production. The etiology of increased and inefficient ventilatory response to exercise in heart disease is multifactorial, involving both peripheral and central mechanisms. Exercise training has been recommended as non-pharmacological treatment for patients with different chronic cardiopulmonary diseases. In this respect, previous studies have reported improvements in ventilatory efficiency after aerobic exercise training in patients with heart disease. Against this background, the primary objective of the present review was to discuss the pathophysiological mechanisms involved in abnormal ventilatory response to exercise, with an emphasis on both patients with heart failure syndrome and coronary artery disease. Secondly, special focus was dedicated to the role of aerobic exercise training in improving indices of ventilatory efficiency among these patients, as well as to the underlying mechanisms involved.

Ventilatory and circulatory responses at the onset of exercise in man following heart or heart-lung transplantation.

PubMed Central

Banner, N; Guz, A; Heaton, R; Innes, J A; Murphy, K; Yacoub, M

1988-01-01

1. Ventilatory and cardiovascular responses to the onset of voluntary and electrically induced leg exercise were studied in six patients following heart transplantation and five following heart-lung transplantation; the results were compared between the patient groups and also with responses from a group of normal subjects. 2. Oxygen consumption, carbon dioxide production and ventilation and its components were measured over two 30 s periods prior to, and two 30 s periods following, the onset of exercise. Relative changes in stroke volume and cardiac output were derived from ensemble-averaged Doppler measurements of ascending aortic blood velocity over the same 30 s periods. 3. None of the groups of subjects showed any significant differences in responses to voluntary exercise compared to electrically induced exercise of similar work pattern and intensity. 4. Compared to normal controls, the transplanted subjects showed higher resting heart rates which did not increase at the onset of exercise; stroke volume increased, but less than in the normal subjects. The resulting cardiac output increases in the transplanted subjects were minimal compared to the normal subjects. 5. Ventilation and oxygen uptake increased immediately and with similar magnitude in all three groups. 6. These results show that in the same individual it is possible to have an appropriate ventilatory response to the onset of exercise in the presumed absence of a normal corticospinal input to the exercising muscles (electrically induced exercise) and afferent neural information from the lungs and heart, and in the absence of a normal circulatory response to exercise. The mechanisms underlying this ventilatory response remain undetermined. PMID:3136247

Respiratory acidosis

MedlinePlus

Ventilatory failure; Respiratory failure; Acidosis - respiratory ... Causes of respiratory acidosis include: Diseases of the airways (such as asthma and COPD ) Diseases of the lung tissue (such as ...

The influence of chronic hypoxia upon chemoreception

PubMed Central

Powell, Frank L.

2007-01-01

Carotid body chemoreceptors are essential for time-dependent changes in ventilatory control during chronic hypoxia. Early theories of ventilatory acclimatization to hypoxia focused on time-dependent changes in known ventilatory stimuli, such as small changes in arterial pH that may play a significant role in some species. However, plasticity in the cellular and molecular mechanisms of carotid body chemoreception play a major role in ventilatory acclimatization to hypoxia in all species studied. Chronic hypoxia causes changes in (a) ion channels (potassium, sodium, calcium) to increase glomus cell excitability, and (b) neurotransmitters (dopamine, acetylcholine, ATP) and neuromodulators (endothelin-1) to increase carotid body afferent activity for a given PO2 and optimize O2-sensitivity. O2-sensing heme-containing molecules in the carotid body have not been studied in chronic hypoxia. Plasticity in medullary respiratory centers processing carotid body afferent input also contributes to ventilatory acclimatization to hypoxia. It is not known if the same mechanisms occur in patients with chronic hypoxemia from lung disease or high altitude natives. PMID:17291837

Subclinical pulmonary function defects following autologous and allogeneic bone marrow transplantation: relationship to total body irradiation and graft-versus-host disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tait, R.C.; Burnett, A.K.; Robertson, A.G.

1991-06-01

Pulmonary function results pre- and post-transplant, to a maximum of 4 years, were analyzed in 98 patients with haematological disorders undergoing allogeneic (N = 53) or autologous bone marrow transplantation (N = 45) between 1982 and 1988. All received similar total body irradiation based regimens ranging from 9.5 Gy as a single fraction to 14.4 Gy fractionated. FEV1/FVC as a measure of airway obstruction showed little deterioration except in patients experiencing graft-versus-host disease in whom statistically significant obstructive ventilatory defects were evident by 6 months post-transplant (p less than 0.01). These defects appeared to be permanent. Restrictive ventilatory defects, asmore » measured by reduction in TLC, and defects in diffusing capacity (DLCO and KCO) were also maximal at 6 months post-transplant (p less than 0.01). Both were related, at least in part, to the presence of GVHD (p less than 0.01) or use of single fraction TBI with absorbed lung dose of 8.0 Gy (p less than 0.05). Fractionated TBI resulted in less marked restricted ventilation and impaired gas exchange, which reverted to normal by 2 years, even when the lung dose was increased from 11.0 Gy to between 12.0 and 13.5 Gy. After exclusion of patients with GVHD (30% allografts) there was no significant difference in pulmonary function abnormalities between autograft and allograft recipients.« less

Rationale and study design for an individualized perioperative open lung ventilatory strategy (iPROVE): study protocol for a randomized controlled trial.

PubMed

Ferrando, Carlos; Soro, Marina; Canet, Jaume; Unzueta, Ma Carmen; Suárez, Fernando; Librero, Julián; Peiró, Salvador; Llombart, Alicia; Delgado, Carlos; León, Irene; Rovira, Lucas; Ramasco, Fernando; Granell, Manuel; Aldecoa, César; Diaz, Oscar; Balust, Jaume; Garutti, Ignacio; de la Matta, Manuel; Pensado, Alberto; Gonzalez, Rafael; Durán, M Eugenia; Gallego, Lucia; Del Valle, Santiago García; Redondo, Francisco J; Diaz, Pedro; Pestaña, David; Rodríguez, Aurelio; Aguirre, Javier; García, Jose M; García, Javier; Espinosa, Elena; Charco, Pedro; Navarro, Jose; Rodríguez, Clara; Tusman, Gerardo; Belda, Francisco Javier

2015-04-27

Postoperative pulmonary and non-pulmonary complications are common problems that increase morbidity and mortality in surgical patients, even though the incidence has decreased with the increased use of protective lung ventilation strategies. Previous trials have focused on standard strategies in the intraoperative or postoperative period, but without personalizing these strategies to suit the needs of each individual patient and without considering both these periods as a global perioperative lung-protective approach. The trial presented here aims at comparing postoperative complications when using an individualized ventilatory management strategy in the intraoperative and immediate postoperative periods with those when using a standard protective ventilation strategy in patients scheduled for major abdominal surgery. This is a comparative, prospective, multicenter, randomized, and controlled, four-arm trial that will include 1012 patients with an intermediate or high risk for postoperative pulmonary complications. The patients will be divided into four groups: (1) individualized perioperative group: intra- and postoperative individualized strategy; (2) intraoperative individualized strategy + postoperative continuous positive airway pressure (CPAP); (3) intraoperative standard ventilation + postoperative CPAP; (4) intra- and postoperative standard strategy (conventional strategy). The primary outcome is a composite analysis of postoperative complications. The Individualized Perioperative Open-lung Ventilatory Strategy (iPROVE) is the first multicenter, randomized, and controlled trial to investigate whether an individualized perioperative approach prevents postoperative pulmonary complications. Registered on 5 June 2014 with identification no. NCT02158923 .

Insulation workers in Belfast. 2. Morbidity in men still at work

PubMed Central

Langlands, Jean H. M.; Wallace, William F. M.; Simpson, Marion J. C.

1971-01-01

Langlands, Jean H. M., Wallace, W. F. M., and Simpson, Marion J. C. (1971).Brit. J. industr. Med.,28, 217-225. Insulation workers in Belfast. 2. Morbidity in men still at work. Two hundred and fifty-two (93%) of the insulation workers in Belfast were examined by chest ϰ-ray, questionnaire, clinical examination, and tests of respiratory function. The frequency of chest ϰ-ray abnormality, lung field or pleural, increased from 13% in men who had worked for less than 10 years to 85% in men who had worked for 30 or more years in the industry. Pleural calcification was found in 15 ϰ-rays. There was evidence suggesting that some men had pleural fibrosis or calcification due to exposure to asbestos in childhood. Rales were present in 61% and clubbing in 11% of men with lung field abnormality, but these were not common when the ϰ-rays showed only pleural abnormality. Where the lung fields were involved there was a restrictive defect with impairment in lung function most marked in the forced vital capacity and single breath carbon monoxide transfer factor, but where the pleura was involved without lung field involvement there was a tendency to impairment of ventilatory function with a normal transfer factor. Cigarette smoking was associated with a greater impairment of lung function than was ϰ-ray abnormality. PMID:5557842

Clinical review: Positive end-expiratory pressure and cardiac output

PubMed Central

Luecke, Thomas; Pelosi, Paolo

2005-01-01

In patients with acute lung injury, high levels of positive end-expiratory pressure (PEEP) may be necessary to maintain or restore oxygenation, despite the fact that 'aggressive' mechanical ventilation can markedly affect cardiac function in a complex and often unpredictable fashion. As heart rate usually does not change with PEEP, the entire fall in cardiac output is a consequence of a reduction in left ventricular stroke volume (SV). PEEP-induced changes in cardiac output are analyzed, therefore, in terms of changes in SV and its determinants (preload, afterload, contractility and ventricular compliance). Mechanical ventilation with PEEP, like any other active or passive ventilatory maneuver, primarily affects cardiac function by changing lung volume and intrathoracic pressure. In order to describe the direct cardiocirculatory consequences of respiratory failure necessitating mechanical ventilation and PEEP, this review will focus on the effects of changes in lung volume, factors controlling venous return, the diastolic interactions between the ventricles and the effects of intrathoracic pressure on cardiac function, specifically left ventricular function. Finally, the hemodynamic consequences of PEEP in patients with heart failure, chronic obstructive pulmonary disease and acute respiratory distress syndrome are discussed. PMID:16356246

Pathogenesis of central and complex sleep apnoea.

PubMed

Orr, Jeremy E; Malhotra, Atul; Sands, Scott A

2017-01-01

Central sleep apnoea (CSA) - the temporary absence or diminution of ventilatory effort during sleep - is seen in a variety of forms including periodic breathing in infancy and healthy adults at altitude and Cheyne-Stokes respiration in heart failure. In most circumstances, the cyclic absence of effort is paradoxically a consequence of hypersensitive ventilatory chemoreflex responses to oppose changes in airflow, that is elevated loop gain, leading to overshoot/undershoot ventilatory oscillations. Considerable evidence illustrates overlap between CSA and obstructive sleep apnoea (OSA), including elevated loop gain in patients with OSA and the presence of pharyngeal narrowing during central apnoeas. Indeed, treatment of OSA, whether via continuous positive airway pressure (CPAP), tracheostomy or oral appliances, can reveal CSA, an occurrence referred to as complex sleep apnoea. Factors influencing loop gain include increased chemosensitivity (increased controller gain), reduced damping of blood gas levels (increased plant gain) and increased lung to chemoreceptor circulatory delay. Sleep-wake transitions and pharyngeal dilator muscle responses effectively raise the controller gain and therefore also contribute to total loop gain and overall instability. In some circumstances, for example apnoea of infancy and central congenital hypoventilation syndrome, central apnoeas are the consequence of ventilatory depression and defective ventilatory responses, that is low loop gain. The efficacy of available treatments for CSA can be explained in terms of their effects on loop gain, for example CPAP improves lung volume (plant gain), stimulants reduce the alveolar-inspired PCO 2 difference and supplemental oxygen lowers chemosensitivity. Understanding the magnitude of loop gain and the mechanisms contributing to instability may facilitate personalized interventions for CSA. © 2016 Asian Pacific Society of Respirology.

Respiratory function in wind instrument players.

PubMed

Zuskin, Eugenija; Mustajbegovic, Jadranka; Schachter, E N; Kern, Josipa; Vitale, Ksenija; Pucarin-Cvetkovic, Jasna; Chiarelli, A; Milosevic, M; Jelinic, Jagoda Doko

2009-01-01

The playing of wind instruments has been associated with changes in respiratory function. To investigate the effect of playing wind instruments on lung function and respiratory symptoms. The present study included 99 wind instrument players and a group of 41 string instrument players as a control from 3 major orchestras in Zagreb, Croatia. Data on chronic respiratory symptoms were recorded in all studied subjects. Lung function was measured in wind instrument players by recording maximum expiratory flow-volume curves. Wind instrument players demonstrated significantly higher prevalences of sinusitis, nasal catarrh and hoarseness compared to control musicians. One wind instrument player developed asthma associated with his work. Odds ratios for wind instrument players were significant for chronic cough, chronic phlegm and chronic bronchitis by smoking habit (p<0.05 or p<0.01) but not for length of employment. Ventilatory capacity data indicate that wind instrument players had significantly greater FEV1 (smokers and nonsmokers) as well as FEF50 (nonsmokers) (p<0.05) compared to predicted values. Regression analysis of pulmonary function tests in wind instrument players demonstrate a significant link between FEV1 and FEF50 and length of employment. Those wind instrument players with longer employment had the greatest increases in lung function. Our data suggest that musicians playing wind instruments may be susceptible to chronic upper airway symptoms. Interestingly wind instrument playing may be associated with higher than expected lung function parameters.

Effect of venous (gut) CO2 loading on intrapulmonary gas fractions and ventilation in the tegu lizard.

PubMed

Ballam, G O; Donaldson, L A

1988-01-01

Studies were conducted to determine regional pulmonary gas concentrations in the tegu lizard lung. Additionally, changes in pulmonary gas concentrations and ventilatory patterns caused by elevating venous levels of CO2 by gut infusion were measured. It was found that significant stratification of lung gases was present in the tegu and that dynamic fluctuations of CO2 concentration varied throughout the length of the lung. Mean FCO2 was greater and FO2 less in the posterior regions of the lung. In the posterior regions gas concentrations remained nearly constant, whereas in the anterior regions large swings were observed with each breath. In the most anterior sections of the lung near the bronchi, CO2 and O2 concentrations approached atmospheric levels during inspiration and posterior lung levels during expiration. During gut loading of CO2, the rate of rise of CO2 during the breathing pause increased. The mean level of CO2 also increased. Breathing rate and tidal volume increased to produce a doubling of VE. These results indicate that the method of introduction of CO2 into the tegu respiratory system determines the ventilatory response. If the CO2 is introduced into the venous blood a dramatic increase in ventilation is observed. If the CO2 is introduced into the inspired air a significant decrease in ventilation is produced. The changes in pulmonary CO2 environment caused by inspiratory CO2 loading are different from those caused by venous CO2 loading. We hypothesize that the differences in pulmonary CO2 environment caused by either inspiratory CO2 loading or fluctuations in venous CO2 concentration act differently on the IPC. The differing response of the IPC to the two methods of CO2 loading is the cause of the opposite ventilatory response seen during either venous or inspiratory loading.

Breathing pattern and chest wall volumes during exercise in patients with cystic fibrosis, pulmonary fibrosis and COPD before and after lung transplantation.

PubMed

Wilkens, H; Weingard, B; Lo Mauro, A; Schena, E; Pedotti, A; Sybrecht, G W; Aliverti, A

2010-09-01

Pulmonary fibrosis (PF), cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD) often cause chronic respiratory failure (CRF). In order to investigate if there are different patterns of adaptation of the ventilatory pump in CRF, in three groups of lung transplant candidates with PF (n=9, forced expiratory volume in 1 s (FEV(1))=37+/-3% predicted, forced vital capacity (FVC)=32+/-2% predicted), CF (n=9, FEV(1)=22+/-3% predicted, FVC=30+/-3% predicted) and COPD (n=21, FEV(1)=21+/-1% predicted, FVC=46+/-2% predicted), 10 healthy controls and 16 transplanted patients, total and compartmental chest wall volumes were measured by opto-electronic plethysmography during rest and exercise. Three different breathing patterns were found during CRF in PF, CF and COPD. Patients with COPD were characterised by a reduced duty cycle at rest and maximal exercise (34+/-1%, p<0.001), while patients with PF and CF showed an increased breathing frequency (49+/-6 and 34+/-2/min, respectively) and decreased tidal volume (0.75+/-0.10 and 0.79+/-0.07 litres) (p<0.05). During exercise, end-expiratory chest wall and rib cage volumes increased significantly in patients with COPD and CF but not in those with PF. End-inspiratory volumes did not increase in CF and PF. The breathing pattern of transplanted patients was similar to that of healthy controls. There are three distinct patterns of CRF in patients with PF, CF and COPD adopted by the ventilatory pump to cope with the underlying lung disease that may explain why patients with PF and CF are prone to respiratory failure earlier than patients with COPD. After lung transplantation the chronic adaptations of the ventilatory pattern to advanced lung diseases are reversible and indicate that the main contributing factor is the lung itself rather than systemic effects of the disease.

Coupling of EIT with computational lung modeling for predicting patient-specific ventilatory responses.

PubMed

Roth, Christian J; Becher, Tobias; Frerichs, Inéz; Weiler, Norbert; Wall, Wolfgang A

2017-04-01

Providing optimal personalized mechanical ventilation for patients with acute or chronic respiratory failure is still a challenge within a clinical setting for each case anew. In this article, we integrate electrical impedance tomography (EIT) monitoring into a powerful patient-specific computational lung model to create an approach for personalizing protective ventilatory treatment. The underlying computational lung model is based on a single computed tomography scan and able to predict global airflow quantities, as well as local tissue aeration and strains for any ventilation maneuver. For validation, a novel "virtual EIT" module is added to our computational lung model, allowing to simulate EIT images based on the patient's thorax geometry and the results of our numerically predicted tissue aeration. Clinically measured EIT images are not used to calibrate the computational model. Thus they provide an independent method to validate the computational predictions at high temporal resolution. The performance of this coupling approach has been tested in an example patient with acute respiratory distress syndrome. The method shows good agreement between computationally predicted and clinically measured airflow data and EIT images. These results imply that the proposed framework can be used for numerical prediction of patient-specific responses to certain therapeutic measures before applying them to an actual patient. In the long run, definition of patient-specific optimal ventilation protocols might be assisted by computational modeling. NEW & NOTEWORTHY In this work, we present a patient-specific computational lung model that is able to predict global and local ventilatory quantities for a given patient and any selected ventilation protocol. For the first time, such a predictive lung model is equipped with a virtual electrical impedance tomography module allowing real-time validation of the computed results with the patient measurements. First promising results obtained in an acute respiratory distress syndrome patient show the potential of this approach for personalized computationally guided optimization of mechanical ventilation in future. Copyright © 2017 the American Physiological Society.

[Extracorporeal membrane oxygenation in primary graft dysfunction in a paediatric double lung transplant: presentation of a case].

PubMed

López-Cantero, M; Grisolía, A L; Vicente, R; Moreno, I; Ramos, F; Porta, J; Torregrosa, S

2014-04-01

Primary graft dysfunction is a leading cause of morbimortality in the immediate postoperative period of patients undergoing lung transplantation. Among the treatment options are: lung protective ventilatory strategies, nitric oxide, lung surfactant therapy, and supportive treatment with extracorporeal membrane oxygenation (ECMO) as a bridge to recovery of lung function or re-transplant. We report the case of a 9-year-old girl affected by cystic fibrosis who underwent double-lung transplantation complicated with a severe primary graft dysfunction in the immediate postoperative period and refractory to standard therapies. Due to development of multiple organ failure, it was decided to insert arteriovenous ECMO catheters (pulmonary artery-right atrium). The postoperative course was satisfactory, allowing withdrawal of ECMO on the 5th post-surgical day. Currently the patient survives free of rejection and with an excellent quality of life after 600 days of follow up. Copyright © 2012 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España. All rights reserved.

Modeling pressure relationships of inspired air into the human lung bifurcations through simulations

NASA Astrophysics Data System (ADS)

Aghasafari, Parya; Ibrahim, Israr B. M.; Pidaparti, Ramana

2018-03-01

Applied pressure on human lung wall has great importance on setting up protective ventilatory strategies, therefore, estimating pressure relationships in terms of specific parameters would provide invaluable information specifically during mechanical ventilation (MV). A three-dimensional model from a healthy human lung MRI is analyzed by computational fluid dynamic (CFD), and results for pressure are curve fitted to estimate relationships that associate pressure to breathing time, cross section and generation numbers of intended locations. Among all possible functions, it is observed that exponential and polynomial pressure functions present most accurate results for normal breathing (NB) and MV, respectively. For validation, pressure-location curves from CFD and results from this study are compared and good correlations are found. Also, estimated pressure values are used to calculate pressure drop and airway resistance to the induced air into the lung bifurcations. It is concluded that maximum pressure drop appeared in generation number 2 and medium sized airways show higher resistance to air flow and that resistance decreased as cross sectional area increased through the model. Results from this study are in good agreement with previous studies and provide potentials for further studies on influence of air pressure on human lung tissue and reducing lung injuries during MV.

[Preliminary study of clinical significance of decreased D(L)CO in patients with left ventricular heart failure].

PubMed

Tan, Xiao-yue; Sun, Xing-guo; Hu, Sheng-shou; Zhang, Jian; Huang, Jie; Chen, Zhi-gao; Ma, Li

2015-07-01

This study aimed to investigate the feature of D(L)CO (Diffusion Lung Capacity for Carbon Monoxide) in CHF (left ventricular heart failure) patients, underlying pathophysiological mechanism and clinical significance. We retrospectively studied the D(L)CO, pulmonary ventilation function, cardiopulmonary exercise testing and related clinical information in severer HF patients. Peak VO2 severely decreased to 34 ± 7 percentage of predicted(%pred) and anaerobic threshold to 48 ± 11%pred in all patients. D(L)CO moderately decreased to 63 ± 12%pred and there were 25 patients lower than 80%pred. FVC, FEV1, FEV1/FVC and TLC were 75 ± 14%pred, 71 ± 17%pred, 97 ± 11%pred, and 79 ± 13%pred, which indicated borderline or mild restrictive ventilatory dysfunction. The decrease of D(L)CO was more severe than those of TLC, FEV1 and FVC. For patients with severe CHF, cardiopulmonary exercise function is extremely limited, D(L)CO generally moderately declines and ventilation function is merely mildly limited. D(L)CO is the parameter for cardiopulmonary coupling, reflecting limitation of the cardiovascular dysfunction while without ventilatory limit.

Flow-controlled expiration: a novel ventilation mode to attenuate experimental porcine lung injury.

PubMed

Goebel, U; Haberstroh, J; Foerster, K; Dassow, C; Priebe, H-J; Guttmann, J; Schumann, S

2014-09-01

Whereas the effects of various inspiratory ventilatory modifications in lung injury have extensively been studied, those of expiratory ventilatory modifications are less well known. We hypothesized that the newly developed flow-controlled expiration (FLEX) mode provides a means of attenuating experimental lung injury. Experimental acute respiratory distress syndrome was induced by i.v. injection of oleic acid in 15 anaesthetized and mechanically ventilated pigs. After established lung injury ([Formula: see text]ratio <27 kPa), animals were randomized to either a control group receiving volume-controlled ventilation (VCV) or a treatment group receiving VCV with additional FLEX (VCV+FLEX). At predefined times, lung mechanics and oxygenation were assessed. At the end of the experiment, the pigs were killed, and bronchoalveolar fluid and lung biopsies were taken. Expression of inflammatory cytokines was analysed in lung tissue and bronchoalveolar fluid. Lung injury score was determined on the basis of stained tissue samples. Compared with the control group (VCV; n=8), the VCV+FLEX group (n=7) demonstrated greater dynamic lung compliance and required less PEEP at comparable [Formula: see text] (both P<0.05), had lower regional lung wet-to-dry ratios and lung injury scores (both P<0.001), and showed less thickening of alveolar walls (an indicator of interstitial oedema) and de novo migration of macrophages into lung tissue (both P<0.001). The newly developed FLEX mode is able to attenuate experimental lung injury. FLEX could provide a novel means of lung-protective ventilation. © The Author [2014]. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Daytime Mouthpiece for Continuous Noninvasive Ventilation in Individuals With Amyotrophic Lateral Sclerosis.

PubMed

Bédard, Marie-Eve; McKim, Douglas A

2016-10-01

Noninvasive ventilation (NIV) is commonly used to provide ventilatory support for individuals with amyotrophic lateral sclerosis (ALS). Once 24-h ventilation is required, the decision between invasive tracheostomy ventilation and palliation is often faced. This study describes the use and outcomes of daytime mouthpiece ventilation added to nighttime mask ventilation for continuous NIV in subjects with ALS as an effective alternative. This was a retrospective study of 39 subjects with ALS using daytime mouthpiece ventilation over a 17-y period. Thirty-one subjects were successful with mouthpiece ventilation, 2 were excluded, 2 stopped because of lack of motivation, and 4 with bulbar subscores of the Revised Amyotrophic Lateral Sclerosis Functional Rating Scale (b-ALSFRS-R) between 0 and 3 physically failed to use it consistently. No subject in the successful group had a b-ALSFRS-R score of <6. Thirty of the successful subjects were able to generate a maximum insufflation capacity - vital capacity difference with lung volume recruitment. The median (range) survival to tracheostomy or death from initiation of nocturnal NIV and mouthpiece ventilation were 648 (176-2,188) and 286 (41-1,769) d, respectively. Peak cough flow with lung-volume recruitment >180 L/min at initiation of mouthpiece ventilation was associated with a longer survival (637 ± 468 vs 240 ± 158 d (P = .01). Mouthpiece ventilation provides effective ventilation and prolonged survival for individuals with ALS requiring full-time ventilatory support and maintaining adequate bulbar function. Copyright © 2016 by Daedalus Enterprises.

Respiratory symptoms and ventilatory functions among quarry workers in Edo state, Nigeria

PubMed Central

Isara, Alphonsus Rukevwe; Adam, Vincent Yakubu; Aigbokhaode, Adesuwa Queen; Alenoghena, Innocent Osi

2016-01-01

Introduction Workers in the quarry industries are exposed to hazards resulting from the inhalation of air borne particulates. The study determined the prevalence of respiratory symptoms and assessed ventilatory functions among quarry workers in Edo state, Nigeria. Methods Quarry workers (site workers and office workers) were interviewed using structured questionnaire. FEV1, FVC, FEV1/FVC and PEFR were measured using a KoKo Legend spirometer. Results A total of 113 quarry workers (76 exposure and 37 controls) were studied. The exposure group had significantly higher occurrence of chest tightness (35.5%) compared with 16.2% of the controls (p < 0.05). The occurrence of cough (23.7% versus 13.5%), sputum (21.1% versus 16.2%), and dyspnoea (7.9% versus 5.4%), were higher in exposure groups while wheeze (10.8% versus 10.5%) and nasal congestion (27.0% and 25.0%) were higher in the control groups. The mean (SD) FEV1, and FVC were significantly lower among the exposure compared with the control group; 2.77L (0.73) versus 3.14L (0.78), p < 0.05, and 3.48L (0.84) versus 3.89L (0.92), p < 0.05. In both groups, smokers had significantly lower mean (SD) FEV1, FVC and PEFR compared with non-smokers; 2.91L (0.77) versus 3.39L (0.69), p = 0.01, 3.61L (0.91) versus 4.26L (0.74), p < 0.05 and 6.56L (2.43) versus 7.98L (1.67), p < 0.05. Conclusion Chronic exposure to quarry dust is associated with respiratory symptoms and reduced lung function indices among quarry workers. The enforcement of the use of PPEs and periodic evaluation the lung function status of quarry workers is advocated. PMID:27347301

Respiratory symptoms and ventilatory functions among quarry workers in Edo state, Nigeria.

PubMed

Isara, Alphonsus Rukevwe; Adam, Vincent Yakubu; Aigbokhaode, Adesuwa Queen; Alenoghena, Innocent Osi

2016-01-01

Workers in the quarry industries are exposed to hazards resulting from the inhalation of air borne particulates. The study determined the prevalence of respiratory symptoms and assessed ventilatory functions among quarry workers in Edo state, Nigeria. Quarry workers (site workers and office workers) were interviewed using structured questionnaire. FEV1, FVC, FEV1/FVC and PEFR were measured using a KoKo Legend spirometer. A total of 113 quarry workers (76 exposure and 37 controls) were studied. The exposure group had significantly higher occurrence of chest tightness (35.5%) compared with 16.2% of the controls (p < 0.05). The occurrence of cough (23.7% versus 13.5%), sputum (21.1% versus 16.2%), and dyspnoea (7.9% versus 5.4%), were higher in exposure groups while wheeze (10.8% versus 10.5%) and nasal congestion (27.0% and 25.0%) were higher in the control groups. The mean (SD) FEV1, and FVC were significantly lower among the exposure compared with the control group; 2.77L (0.73) versus 3.14L (0.78), p < 0.05, and 3.48L (0.84) versus 3.89L (0.92), p < 0.05. In both groups, smokers had significantly lower mean (SD) FEV1, FVC and PEFR compared with non-smokers; 2.91L (0.77) versus 3.39L (0.69), p = 0.01, 3.61L (0.91) versus 4.26L (0.74), p < 0.05 and 6.56L (2.43) versus 7.98L (1.67), p < 0.05. Chronic exposure to quarry dust is associated with respiratory symptoms and reduced lung function indices among quarry workers. The enforcement of the use of PPEs and periodic evaluation the lung function status of quarry workers is advocated.

The Link between Reduced Inspiratory Capacity and Exercise Intolerance in Chronic Obstructive Pulmonary Disease.

PubMed

O'Donnell, Denis E; Elbehairy, Amany F; Webb, Katherine A; Neder, J Alberto

2017-07-01

Low inspiratory capacity (IC), chronic dyspnea, and reduced exercise capacity are inextricably linked and are independent predictors of increased mortality in chronic obstructive pulmonary disease. It is no surprise, therefore, that a major goal of management is to improve IC by reducing lung hyperinflation to improve respiratory symptoms and health-related quality of life. The negative effects of lung hyperinflation on respiratory muscle and cardiocirculatory function during exercise are now well established. Moreover, there is growing appreciation that a key mechanism of exertional dyspnea in chronic obstructive pulmonary disease is critical mechanical constraints on tidal volume expansion during exercise when resting IC is reduced. Further evidence for the importance of lung hyperinflation comes from multiple studies, which have reported the clinical benefits of therapeutic interventions that reduce lung hyperinflation and increase IC. A reduced IC in obstructive pulmonary disease is further eroded by exercise and contributes to ventilatory limitation and dyspnea. It is an important outcome for both clinical and research studies.

Impact of switching from Caucasian to Indian reference equations for spirometry interpretation.

PubMed

Chhabra, S K; Madan, M

2018-03-01

In the absence of ethnically appropriate prediction equations, spirometry data in Indian subjects are often interpreted using equations for other ethnic populations. To evaluate the impact of switching from Caucasian (National Health and Nutrition Examination Survey III [NHANES III] and Global Lung Function Initiative [GLI]) equations to the recently published North Indian equations on spirometric interpretation, and to examine the suitability of GLI-Mixed equations for this population. Spirometry data on 12 323 North Indian patients were analysed using the North Indian equations as well as NHANES III, GLI-Caucasian and GLI-Mixed equations. Abnormalities and ventilatory patterns were categorised and agreement in interpretation was evaluated. The NHANES III and GLI-Caucasian equations and, to a lesser extent, the GLI-Mixed equations, predicted higher values and labelled more measurements as abnormal. In up to one third of the patients, these differed from Indian equations in the categorisation of ventilatory patterns, with more patients classified as having restrictive and mixed disease. The NHANES III and GLI-Caucasian equations substantially overdiagnose abnormalities and misclassify ventilatory patterns on spirometry in Indian patients. Such errors of interpretation, although less common with the GLI-Mixed equations, remain substantial and are clinically unacceptable. A switch to Indian equations will have a major impact on interpretation.

Monitoring of pulmonary mechanics in acute respiratory distress syndrome to titrate therapy.

PubMed

Gattinoni, Luciano; Eleonora, Carlesso; Caironi, Pietro

2005-06-01

This paper reviews recent findings regarding the respiratory mechanics during acute respiratory distress syndrome as a tool for tailoring its ventilatory management. The pressure-volume curve has been used for many years as a descriptor of the respiratory mechanics in patients affected by acute respiratory distress syndrome. The use of the sigmoidal equation introduced by Venegas for the analysis of the pressure-volume curve seems to be the most rigorous mathematical approach to assessing lung mechanics. Increasing attention has been focused on the deflation limb for titration of positive end-expiratory pressure. Based on physiologic reasoning, a novel parameter, the stress index, has been proposed for tailoring a safe mechanical ventilation, although its clinical impact has still to be proved. Evidence has confirmed that a variety of underlying pathologies may lead to acute respiratory distress syndrome, making unrealistic any attempt to unify the ventilatory approach. Although extensively proposed to tailor mechanical ventilation during acute respiratory distress syndrome, there is no evidence that the pressure-volume curve may be useful in setting a lung-protective strategy in the presence of different potentials for recruitment. The Venegas approach should be the standard analysis of pressure-volume curves. In any patient, the potential for recruitment should be assessed, as a basis for tailoring the most effective mechanical ventilation. Further studies are needed to clarify the potential use of the pressure-volume curve to guide a lung-protective ventilatory strategy.

Persistent lung oscillator response to CO2 after buccal oscillator inhibition in the adult frog.

PubMed

Leclère, Renaud; Straus, Christian; Similowski, Thomas; Bodineau, Laurence; Fiamma, Marie-Noëlle

2012-08-15

The automatic ventilatory drive in amphibians depends on two oscillators interacting with each other, the gill/buccal and lung oscillators. The lung oscillator would be homologous to the mammalian pre-Bötzinger complex and the gill/buccal oscillator homologous to the mammalian parafacial respiratory group/retrotrapezoid nucleus (pFRG/RTN). Dysfunction of the pFRG/RTN has been involved in the development of respiratory diseases associated to the loss of CO(2) chemosensitivity such as the congenital central hypoventilation syndrome. Here, on adult in vitro isolated frog brainstem, consequences of the buccal oscillator inhibition (by reducing Cl(-)) were evaluated on the respiratory rhythm developed by the lung oscillator under hypercapnic challenges. Our results show that under low Cl(-) concentration (i) the buccal oscillator is strongly inhibited and the lung burst frequency and amplitude decreased and (ii) it persists a powerful CO(2) chemosensitivity. In conclusion, in frog, the CO(2) chemosensitivity depends on cellular contingent(s) whose the functioning is independent of the concentration of Cl(-) and origin remains unknown. Copyright © 2012 Elsevier B.V. All rights reserved.

Localization of essential rhombomeres for respiratory rhythm generation in bullfrog tadpoles using a binary search algorithm: Rhombomere 7 is essential for the gill rhythm and suppresses lung bursts before metamorphosis.

PubMed

Duchcherer, Maryana; Baghdadwala, Mufaddal I; Paramonov, Jenny; Wilson, Richard J A

2013-12-01

Frog metamorphosis includes transition from water breathing to air breathing but the extent to which such a momentous change in behavior requires fundamental changes in the organization of the brainstem respiratory circuit is unknown. Here, we combine a vertically mounted isolated brainstem preparation, "the Sheep Dip," with a search algorithm used in computer science, to identify essential rhombomeres for generation of ventilatory motor bursts in metamorphosing bullfrog tadpoles. Our data suggest that rhombomere 7, which in mammals hosts the PreBötC (PreBötzinger Complex; the likely inspiratory oscillator), is essential for gill and buccal bursts. Whereas rhombomere 5, in close proximity to a brainstem region associated with the mammalian expiratory oscillator, is essential for lung bursts at both stages. Therefore, we conclude there is no rhombomeric translocation of respiratory oscillators in bullfrogs as previously suggested. In premetamorphic tadpoles, functional ablation of rhombomere 7 caused ectopic expression of precocious lung bursts, suggesting the gill oscillator suppresses an otherwise functional lung oscillator in early development. Copyright © 2013 Wiley Periodicals, Inc.

Lungs in Heart Failure

PubMed Central

Apostolo, Anna; Giusti, Giuliano; Gargiulo, Paola; Bussotti, Maurizio; Agostoni, Piergiuseppe

2012-01-01

Lung function abnormalities both at rest and during exercise are frequently observed in patients with chronic heart failure, also in the absence of respiratory disease. Alterations of respiratory mechanics and of gas exchange capacity are strictly related to heart failure. Severe heart failure patients often show a restrictive respiratory pattern, secondary to heart enlargement and increased lung fluids, and impairment of alveolar-capillary gas diffusion, mainly due to an increased resistance to molecular diffusion across the alveolar capillary membrane. Reduced gas diffusion contributes to exercise intolerance and to a worse prognosis. Cardiopulmonary exercise test is considered the “gold standard” when studying the cardiovascular, pulmonary, and metabolic adaptations to exercise in cardiac patients. During exercise, hyperventilation and consequent reduction of ventilation efficiency are often observed in heart failure patients, resulting in an increased slope of ventilation/carbon dioxide (VE/VCO2) relationship. Ventilatory efficiency is as strong prognostic and an important stratification marker. This paper describes the pulmonary abnormalities at rest and during exercise in the patients with heart failure, highlighting the principal diagnostic tools for evaluation of lungs function, the possible pharmacological interventions, and the parameters that could be useful in prognostic assessment of heart failure patients. PMID:23365739

Mechanical ventilatory constraints during incremental cycle exercise in human pregnancy: implications for respiratory sensation

PubMed Central

Jensen, Dennis; Webb, Katherine A; Davies, Gregory A L; O'Donnell, Denis E

2008-01-01

The aim of this study was to identify the physiological mechanisms of exertional respiratory discomfort (breathlessness) in pregnancy by comparing ventilatory (breathing pattern, airway function, operating lung volumes, oesophageal pressure (Poes)-derived indices of respiratory mechanics) and perceptual (breathlessness intensity) responses to incremental cycle exercise in 15 young, healthy women in the third trimester (TM3; between 34 and 38 weeks gestation) and again 4–5 months postpartum (PP). During pregnancy, resting inspiratory capacity (IC) increased (P < 0.01) and end-expiratory lung volume decreased (P < 0.001), with no associated change in total lung capacity (TLC) or static respiratory muscle strength. This permitted greater tidal volume (VT) expansion throughout exercise in TM3, while preserving the relationship between contractile respiratory muscle effort (tidal Poes swing expressed as a percentage of maximum inspiratory pressure (PImax)) and thoracic volume displacement (VT expressed as a percentage of vital capacity) and between breathlessness and ventilation (V̇E). At the highest equivalent work rate (HEWR = 128 ± 5 W) in TM3 compared with PP: V̇E, tidal Poes/PImax and breathlessness intensity ratings increased by 10.2 l min−1 (P < 0.001), 8.8%PImax (P < 0.05) and 0.9 Borg units (P < 0.05), respectively. Pulmonary resistance was not increased at rest or during exercise at the HEWR in TM3, despite marked increases in mean tidal inspiratory and expiratory flow rates, suggesting increased bronchodilatation. Dynamic mechanical constraints on VT expansion (P < 0.05) with associated increased breathlessness intensity ratings (P < 0.05) were observed near peak exercise in TM3 compared with PP. In conclusion: (1) pregnancy-induced increases in exertional breathlessness reflected the normal awareness of increased V̇E and contractile respiratory muscle effort; (2) mechanical adaptations of the respiratory system, including recruitment of resting IC and increased bronchodilatation, accommodated the increased VT while preserving effort–displacement and breathlessness–V̇E relationships; and (3) dynamic mechanical ventilatory constraints contributed to respiratory discomfort near the limits of tolerance in late gestation. PMID:18687714

Viral and Mycoplasma pneumoniae pneumonias in school-age children: three-year follow-up of respiratory function.

PubMed

Todisco, T; de Benedictis, F M; Dottorini, M

1989-01-01

We studied the evolution of respiratory function during and for 3 years after the acute onset of viral and Mycoplasma pneumoniae pneumonias in 13 school-age children. A mixed type transient ventilatory defect (restrictive and obstructive, but mainly restrictive) with large and small airway involvement was observed during the acute phase of the pneumonias. Residual small airway involvement was found over the next 12 months, but no pulmonary function abnormalities were present after 3 years. At that time, one of the 13 subjects displayed bronchial hyperreactivity to distilled water mist challenge. The authors concluded that viral and Mycoplasma pneumoniae pneumonia in previously healthy school-age children does not cause impaired lung function in later childhood.

Effects of septum and pericardium on heart-lung interactions in a cardiopulmonary simulation model.

PubMed

Karamolegkos, Nikolaos; Albanese, Antonio; Chbat, Nicolas W

2017-07-01

Mechanical heart-lung interactions are often overlooked in clinical settings. However, their impact on cardiac function can be quite significant. Mechanistic physiology-based models can provide invaluable insights into such cardiorespiratory interactions, which occur not only under external mechanical ventilatory support but in normal physiology as well. In this work, we focus on the cardiac component of a previously developed mathematical model of the human cardiopulmonary system, aiming to improve the model's response to the intrathoracic pressure variations that are associated with the respiratory cycle. Interventricular septum and pericardial membrane are integrated into the existing model. Their effect on the overall cardiac response is explained by means of comparison against simulation results from the original model as well as experimental data from literature.

Perfluorodecalin lavage of a longstanding lung atelectasis in a child with spinal muscle atrophy.

PubMed

Henrichsen, Thore; Lindenskov, Paal H H; Shaffer, Thomas H; Loekke, Ruth J V; Fugelseth, Drude; Lindemann, Rolf

2012-04-01

Persistent lung atelectasis is difficult to treat and perfluorochemical (PFC) liquid may be an option for bronchioalveolar lavage (BAL). A 4-year-old girl with spinal muscle atrophy was admitted in respiratory failure. On admission, the X-ray confirmed the persistence of total right-sided lung atelectasis, which had been present for 14 months. She was endotracheally intubated and ventilated from the day of admission. BAL with normal saline was performed twice without improvement. Following failed extubation and being dependent on continuous respiratory support, a trial of BAL using PFC liquid (Perfluorodecalin HP) was carried out. The PFC was delivered through the endotracheal tube on three consecutive days. A loading dose of 3 ml/kg was administered, followed by a varying dose in order to more effectively lavage the lungs. She tolerated the procedure well the first 2 days, although there were no clinical signs of improvement in the atelectasis. Intentionally, higher inflation pressures were applied after PFC instillation on day 3. Chest X-ray then showed hazy infiltrates on her left lung and she required more ventilatory support. However, lung infiltrates cleared over the next 3 days. A tracheotomy was done 6 days after the last PFC instillation. She had a slow recovery and was successfully decanulated. Clinical improvement of lung function was seen including less need of BiPAP and oxygen. A chest CT scan showed then functional lung tissue appearing in the previous total atelectatic right lung. Lavage with PFC can safely be performed with a therapeutic effect in a child with unilateral total lung atelectasis. Copyright © 2011 Wiley Periodicals, Inc.

Pathogenesis of Central and Complex Sleep Apnoea

PubMed Central

Orr, Jeremy E.; Malhotra, Atul; Sands, Scott A.

2016-01-01

Central sleep apnoea (CSA)—the temporary absence or diminution of ventilator effort during sleep—is seen in a variety of forms including periodic breathing in infancy and healthy adults at altitude and Cheyne-Stokes respiration in heart failure. In most circumstances, the cyclic absence of effort is paradoxically a consequence of hypersensitive ventilatory chemoreflex responses to oppose changes in airflow, i.e. elevated loop gain, leading to overshoot/undershoot ventilatory oscillations. Considerable evidence illustrates overlap between CSA and obstructive sleep apnoea (OSA), including elevated loop gain in patients with OSA and the presence of pharyngeal narrowing during central apnoeas. Indeed, treatment of OSA, whether via CPAP, tracheostomy, or oral appliances, can reveal CSA, an occurrence referred to as complex sleep apnoea. Factors influencing loop gain include increased chemosensitivity (increased controller gain), reduced damping of blood gas levels (increased plant gain) and increased lung to chemoreceptor circulatory delay. Sleep-wake transitions and pharyngeal dilator muscle responses effectively raise the controller gain and therefore also contribute to total loop gain and overall instability. In some circumstances, for example apnoea of infancy and central congenital hypoventilation syndrome, central apnoeas are the consequence of ventilatory depression and defective ventilatory responses, i.e. low loop gain. The efficacy of available treatments for CSA can be explained in terms of their effects on loop gain, e.g. CPAP improves lung volume (plant gain), stimulants reduce the alveolar-inspired PCO2 difference, supplemental oxygen lowers chemosensitivity. Understanding the magnitude of loop gain and the mechanisms contributing to instability may facilitate personalised interventions for CSA. PMID:27797160

The training type influence on male elite athletes' ventilatory function.

PubMed

Durmic, Tijana; Lazovic Popovic, Biljana; Zlatkovic Svenda, Mirjana; Djelic, Marina; Zugic, Vladimir; Gavrilovic, Tamara; Mihailovic, Zoran; Zdravkovic, Marija; Leischik, Roman

2017-01-01

To assess and compare measured ventilatory volumes (forced expiratory volume in 1 s (FEV 1 ), peak expirium flow (PEF) and maximal voluntary ventilation (MVV)), ventilatory function capacities (forced vital capacity (FVC) and vital capacity (VC)) and FEV 1 /VC ratio in a sample of power and endurance elite athletes and their age-matched and sex-matched sedentary control group. A cross-sectional study was applied on male elite athletes (n=470) who were classified according to the type of the predominantly performed exercise in the following way: group 1: endurance group (EG=270), group 2: power athletes group (SG=200) and group 3: sedentary control group (CG=100). The lung VC, FVC, FEV 1 , FEV 1 /FVC ratio, PEF and MVV were measured in all of the observed subjects, who were also classified with regard to body mass index (BMI) and the percentage of the body fat (BF%). The CG had the highest BF% value, while the endurance group had the lowest BMI and BF% value, which is significantly different from the other two groups (p<0.05). The observed values of VC, FVC and FEV 1 in the EG were significantly higher than those from the other two groups (p<0.05). There were no differences concerning the observed FEV 1 /FVC ratio. A continued endurance physical activity leads to adaptive changes in spirometric parameters (VC, FVC and FEV 1 ), highlighting the fact that there is a need for specific consideration of different respiratory 'pattern' development in different types of sport, which also has to be further evaluated.

Gas exchange and ventilation during dormancy in the tegu lizard tupinambis merianae

PubMed

de Andrade DV; Abe

1999-12-01

The tegu lizard Tupinambis merianae exhibits an episodic ventilatory pattern when dormant at 17 degrees C but a uniform ventilatory pattern when dormant at 25 degrees C. At 17 degrees C, ventilatory episodes were composed of 1-22 breaths interspaced by non-ventilatory periods lasting 1.8-26 min. Dormancy at the higher body temperature was accompanied by higher rates of O(2) consumption and ventilation. The increase in ventilation was due only to increases in breathing frequency with no change observed in tidal volume. The air convection requirement for O(2) did not differ at the two body temperatures. The respiratory quotient was 0.8 at 17 degrees C and 1.0 at 25 degrees C. We found no consistent relationship between expired gas composition and the start/end of the ventilatory period during episodic breathing at 17 degrees C. However, following non-ventilatory periods of increasing duration, there was an increase in the pulmonary O(2) extraction that was not coupled to an equivalent increase in elimination of CO(2) from the lungs. None of the changes in the variables studied could alone explain the initiation/termination of episodic ventilation in the tegus, suggesting that breathing episodes are shaped by a complex interaction between many variables. The estimated oxidative cost of breathing in dormant tegus at 17 degrees C was equivalent to 52.3 % of the total metabolic rate, indicating that breathing is the most costly activity during dormancy.

Advances in the Evaluation of Respiratory Pathophysiology during Exercise in Chronic Lung Diseases

PubMed Central

O'Donnell, Denis E.; Elbehairy, Amany F.; Berton, Danilo C.; Domnik, Nicolle J.; Neder, J. Alberto

2017-01-01

Dyspnea and exercise limitation are among the most common symptoms experienced by patients with various chronic lung diseases and are linked to poor quality of life. Our understanding of the source and nature of perceived respiratory discomfort and exercise intolerance in chronic lung diseases has increased substantially in recent years. These new mechanistic insights are the primary focus of the current review. Cardiopulmonary exercise testing (CPET) provides a unique opportunity to objectively evaluate the ability of the respiratory system to respond to imposed incremental physiological stress. In addition to measuring aerobic capacity and quantifying an individual's cardiac and ventilatory reserves, we have expanded the role of CPET to include evaluation of symptom intensity, together with a simple “non-invasive” assessment of relevant ventilatory control parameters and dynamic respiratory mechanics during standardized incremental tests to tolerance. This review explores the application of the new advances in the clinical evaluation of the pathophysiology of exercise intolerance in chronic obstructive pulmonary disease (COPD), chronic asthma, interstitial lung disease (ILD) and pulmonary arterial hypertension (PAH). We hope to demonstrate how this novel approach to CPET interpretation, which includes a quantification of activity-related dyspnea and evaluation of its underlying mechanisms, enhances our ability to meaningfully intervene to improve quality of life in these pathologically-distinct conditions. PMID:28275353

Mechanisms of physical activity limitation in chronic lung diseases.

PubMed

Vogiatzis, Ioannis; Zakynthinos, George; Andrianopoulos, Vasileios

2012-01-01

In chronic lung diseases physical activity limitation is multifactorial involving respiratory, hemodynamic, and peripheral muscle abnormalities. The mechanisms of limitation discussed in this paper relate to (i) the imbalance between ventilatory capacity and demand, (ii) the imbalance between energy demand and supply to working respiratory and peripheral muscles, and (iii) the factors that induce peripheral muscle dysfunction. In practice, intolerable exertional symptoms (i.e., dyspnea) and/or leg discomfort are the main symptoms that limit physical performance in patients with chronic lung diseases. Furthermore, the reduced capacity for physical work and the adoption of a sedentary lifestyle, in an attempt to avoid breathlessness upon physical exertion, cause profound muscle deconditioning which in turn leads to disability and loss of functional independence. Accordingly, physical inactivity is an important component of worsening the patients' quality of life and contributes importantly to poor prognosis. Identifying the factors which prevent a patient with lung disease to easily carry out activities of daily living provides a unique as well as important perspective for the choice of the appropriate therapeutic strategy.

Low-flow venovenous CO₂ removal in association with lung protective ventilation strategy in patients who develop severe progressive respiratory acidosis after lung transplantation.

PubMed

Ruberto, F; Bergantino, B; Testa, M C; D'Arena, C; Zullino, V; Congi, P; Paglialunga, S G; Diso, D; Venuta, F; Pugliese, F

2013-09-01

Primary graft dysfunction (PGD) might occur after lung transplantation. In some severe cases, conventional therapies like ventilatory support, administration of inhaled nitric oxide (iNO), and intravenous prostacyclins are not sufficient to provide an adequate gas exchange. The aim of our study was to evaluate the use of a lung protective ventilation strategy associated with a low-flow venovenous CO2 removal treatment to reduce ventilator-associated injury in patients that develop severe PGD after lung transplantation. From January 2009 to January 2011, 3 patients developed PGD within 24 hours after lung transplantation. In addition to conventional medical treatment, including hemodynamic support, iNO and prostaglandin E1 (PGE1), we initiated a ventilatory protective strategy associated with low-flow venovenous CO2 removal treatment (LFVVECCO2R). Hemodynamic and respiratory parameters were assessed at baseline as well as after 3, 12, 24, and 48 hours. No adverse events were registered. Despite decreased baseline elevated pulmonary positive pressures, application of a protective ventilation strategy with LFVVECCO2R reduced PaCO2 and pulmonary infiltrates as well as increased pH values and PaO2/FiO2 ratios. Every patient showed simultaneous improvement of clinical and hemodynamic conditions. They were weaned from mechanical ventilation and extubated after 24 hours after the use of the low-flow venovenous CO2 removal device. The use of LFVVECCO2R together with a protective lung ventilation strategy during the perioperative period of lung transplantation may be a valid clinical strategy for patients with PGD and severe respiratory acidosis occured despite adequate mechanical ventilation. Copyright © 2013 Elsevier Inc. All rights reserved.

IN VIVO COMPARISON OF EPITHELIAL RESPONSES FOR S-8 VERSUS JP-8 JET FUELS BELOW PERMISSIBLE EXPOSURE LIMIT

PubMed Central

Wong, Simon S.; Vargas, Jason; Thomas, Alana; Fastje, Cindy; McLaughlin, Michael; Camponovo, Ryan; Lantz, R. Clark; Heys, Jeffrey; Witten, Mark L.

2010-01-01

This study was designed to characterize and compare the pulmonary effects in distal lung from a low-level exposure to jet propellant-8 fuel (JP-8) and a new synthetic-8 fuel (S-8). It is hypothesized that both fuels have different airway epithelial deposition and responses. Consequently, male C57BL/6 mice were nose-only exposed to S-8 and JP-8 at average concentrations of 53 mg/m3 for 1 hour/day for 7 days. A pulmonary function test performed 24 hr after the final exposure indicated that there was a significant increase in expiratory lung resistance in the S-8 mice, whereas JP-8 mice had significant increases in both inspiratory and expiratory lung resistance compared to control values. Neither significant S-8 nor JP-8 respiratory permeability changes were observed compared to controls, suggesting no loss of epithelial barrier integrity. Morphological examination and morphometric analysis of airway tissue demonstrated that both fuels showed different patterns of targeted epithelial cells: bronchioles in S-8 and alveoli/terminal bronchioles in JP-8. Collectively, our data suggest that both fuels may have partially different deposition patterns, which may possibly contribute to specific different adverse effects in lung ventilatory function. PMID:18930109

Effect of atenolol on ventilatory and cardiac function in asthma.

PubMed Central

Vilsvik, J S; Schaanning, J

1976-01-01

The effects on ventilatory and cardiac function of atenolol, a new cardioselective beta-adrenoceptor blocking agent, were compared with those of practolol in a double-blind trial in 12 patients with asthma. Both drugs impaired ventilatory function--atenolol insignificantly and practolol significantly. Atenolol was if anything more cardioselective than practolol. Neither drug interfered significantly with the bronchodilator response to inhaled isoprenaline. Atenolol is suitable for use in patients for whom practolol would formerly have been chosen because of its cardioselectivity. PMID:8188

Basic principles of respiratory function monitoring in ventilated newborns: A review.

PubMed

Schmalisch, Gerd

2016-09-01

Respiratory monitoring during mechanical ventilation provides a real-time picture of patient-ventilator interaction and is a prerequisite for lung-protective ventilation. Nowadays, measurements of airflow, tidal volume and applied pressures are standard in neonatal ventilators. The measurement of lung volume during mechanical ventilation by tracer gas washout techniques is still under development. The clinical use of capnography, although well established in adults, has not been embraced by neonatologists because of technical and methodological problems in very small infants. While the ventilatory parameters are well defined, the calculation of other physiological parameters are based upon specific assumptions which are difficult to verify. Incomplete knowledge of the theoretical background of these calculations and their limitations can lead to incorrect interpretations with clinical consequences. Therefore, the aim of this review was to describe the basic principles and the underlying assumptions of currently used methods for respiratory function monitoring in ventilated newborns and to highlight methodological limitations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of changing from the National Health and Nutritional Examination Survey III spirometry reference range to that of the Global Lung Initiative 2012 at Gold Coast Hospital and Health Service.

PubMed

Embling, Laura A K; Zagami, Debbie; Sriram, Krishna Bajee; Gordon, Robert J; Sivakumaran, Pathmanathan

2016-12-01

The categorisation of lung disease into obstructive ventilatory defect (OVD) and tendency to a restrictive ventilatory defect (TRVD) patterns using spirometry is used to guide both prognostication and treatment. The effectiveness of categorisation depends upon having reference ranges that accurately represent the population they describe. The Global Lung Initiative 2012 (GLI 2012) has spirometry reference ranges drawn from the largest sample size to date. This study aimed to determine whether using spirometry reference ranges from the new GLI 2012 dataset, compared to the previously used National Health and Nutritional Examination Survey III (NHANES III) dataset, resulted in a change in diagnosis between OVD, TRVD and normal ventilatory pattern (NVP). Spirometry data were collected from 301 patients, aged 18-80 years, undergoing investigation at the Gold Coast Hospital and Health Service (GCHHS) throughout February and March 2014. OVD was defined as a forced expiratory volume in 1 second (FEV 1 ) divided by forced vital capacity (FVC) less than lower limit of normal (LLN). TRVD was defined as FEV 1 /FVC ≥ LLN, FEV 1 < LLN, and FVC < LLN. The LLN values were determined by equations from the GLI and NHANES datasets. Spirometry interpreted using the NHANES III equations showed: 102 individuals (33.9%) with normal spirometry, 136 (45.2%) with an OVD pattern, 52 (17.3%) with a TRVD pattern, and 11 (3.7%) with a mixed pattern. When the spirometry data were interpreted using the GLI 2012 equations 2 (0.7%) individuals changed from OVD to NVP, 2 (0.7%) changed from NVP to OVD and 14 (4.7%) changed from TRVD to NVP. Using the GLI 2012 reference range resulted in a change in diagnosis of lung disease in 5.9% of the individuals included in this study. This variance in diagnosis when changing reference ranges should be taken into account by clinicians as it may affect patient management.

Quantification of asymmetric lung pathophysiology as a guide to the use of simultaneous independent lung ventilation in posttraumatic and septic adult respiratory distress syndrome.

PubMed Central

Siegel, J H; Stoklosa, J C; Borg, U; Wiles, C E; Sganga, G; Geisler, F H; Belzberg, H; Wedel, S; Blevins, S; Goh, K C

1985-01-01

The management of impaired respiratory gas exchange in patients with nonuniform posttraumatic and septic adult respiratory distress syndrome (ARDS) contains its own therapeutic paradox, since the need for volume-controlled ventilation and PEEP in the lung with the most reduced compliance increases pulmonary barotrauma to the better lung. A computer-based system has been developed by which respiratory pressure-flow-volume relations and gas exchange characteristics can be obtained and respiratory dynamic and static compliance curves computed and displayed for each lung, as a means of evaluating the effectiveness of ventilation therapy in ARDS. Using these techniques, eight patients with asymmetrical posttraumatic or septic ARDS, or both, have been managed using simultaneous independent lung ventilation (SILV). The computer assessment technique allows quantification of the nonuniform ARDS pattern between the two lungs. This enabled SILV to be utilized using two synchronized servo-ventilators at different pressure-flow-volumes, inspiratory/expiratory ratios, and PEEP settings to optimize the ventilatory volumes and gas exchange of each lung, without inducing excess barotrauma in the better lung. In the patients with nonuniform ARDS, conventional ventilation was not effective in reducing shunt (QS/QT) or in permitting a lower FIO2 to be used for maintenance of an acceptable PaO2. SILV reduced per cent v-a shunt and permitted a higher PaO2 at lower FIO2. Also, there was x-ray evidence of ARDS improvement in the poorer lung. While the ultimate outcome was largely dependent on the patient's injury and the adequacy of the septic host defense, by utilizing the SILV technique to match the quantitative aspects of respiratory dysfunction in each lung at specific times in the clinical course, it was possible to optimize gas exchange, to reduce barotrauma, and often to reverse apparently fixed ARDS changes. In some instances, this type of physiologically directed ventilatory therapy appeared to contribute to a successful recovery. Images FIG. 10. PMID:3901940

[Current concepts in perioperative management of children : preface and comments].

PubMed

Kuratani, Norifumi; Kikuchi, Hirosato

2007-05-01

In the past few years, pediatric anesthesia management changed rapidly to more evidence-based and patient-oriented practice. It has been emphasized that "focused and individualized" pre-anesthesia evaluation is preferred to routine screening of laboratory tests and X-rays. Anesthesia induction should be less stressful for children through the use of various approaches, such as preoperative preparation, sedative premedication, and parent-present induction. Cuffed tracheal tube is becoming popular for small children, and its indication should be considered individually. Laryngeal mask airway is frequently used for simple short cases. Perioperative fluid infusion therapy has been a controversial issue. Traditional therapeutic regimen using hypotonic solution with glucose is criticized as a result of the growing evidence of hyponatremia and hyperglycemia. New ventilatory modes and sedative medications are now available for pediatric patients, and lung-protective ventilatory strategy should be considered to protect immature lung from ventilator-induced lung injury. Emergence agitation from general anesthesia is an evolving problem. Sevoflurane is known to be a major risk factor for stormy wake-up. Pediatric anesthesiologists should pursue high quality of anesthesia emergence. All anesthesia residency programs should include pediatric rotation; otherwise anesthesia residents will lose opportunities to learn basic concepts of pediatric anesthesia.

Update: Non-Invasive Positive Pressure Ventilation in Chronic Respiratory Failure Due to COPD.

PubMed

Altintas, Nejat

2016-01-01

Long-term non-invasive positive pressure ventilation (NPPV) has widely been accepted to treat chronic hypercapnic respiratory failure arising from different etiologies. Although the survival benefits provided by long-term NPPV in individuals with restrictive thoracic disorders or stable, slowly-progressing neuromuscular disorders are overwhelming, the benefits provided by long-term NPPV in patients with chronic obstructive pulmonary disease (COPD) remain under question, due to a lack of convincing evidence in the literature. In addition, long-term NPPV reportedly failed in the classic trials to improve important physiological parameters such as arterial blood gases, which might serve as an explanation as to why long-term NPPV has not been shown to substantially impact on survival. However, high intensity NPPV (HI-NPPV) using controlled NPPV with the highest possible inspiratory pressures tolerated by the patient has recently been described as a new and promising approach that is well-tolerated and is also capable of improving important physiological parameters such as arterial blood gases and lung function. This clearly contrasts with the conventional approach of low-intensity NPPV (LI-NPPV) that uses considerably lower inspiratory pressures with assisted forms of NPPV. Importantly, HI-NPPV was very recently shown to be superior to LI-NPPV in terms of improved overnight blood gases, and was also better tolerated than LI-NPPV. Furthermore, HI-NPPV, but not LI-NPPV, improved dyspnea, lung function and disease-specific aspects of health-related quality of life. A recent study showed that long-term treatment with NPPV with increased ventilatory pressures that reduced hypercapnia was associated with significant and sustained improvements in overall mortality. Thus, long-term NPPV seems to offer important benefits in this patient group, but the treatment success might be dependent on effective ventilatory strategies.

Ibuprofen Blunts Ventilatory Acclimatization to Sustained Hypoxia in Humans

PubMed Central

Basaran, Kemal Erdem; Villongco, Michael; Ho, Baran; Ellis, Erika; Zarndt, Rachel; Antonova, Julie; Hopkins, Susan R.; Powell, Frank L.

2016-01-01

Ventilatory acclimatization to hypoxia is a time-dependent increase in ventilation and the hypoxic ventilatory response (HVR) that involves neural plasticity in both carotid body chemoreceptors and brainstem respiratory centers. The mechanisms of such plasticity are not completely understood but recent animal studies show it can be blocked by administering ibuprofen, a nonsteroidal anti-inflammatory drug, during chronic hypoxia. We tested the hypothesis that ibuprofen would also block the increase in HVR with chronic hypoxia in humans in 15 healthy men and women using a double-blind, placebo controlled, cross-over trial. The isocapnic HVR was measured with standard methods in subjects treated with ibuprofen (400mg every 8 hrs) or placebo for 48 hours at sea level and 48 hours at high altitude (3,800 m). Subjects returned to sea level for at least 30 days prior to repeating the protocol with the opposite treatment. Ibuprofen significantly decreased the HVR after acclimatization to high altitude compared to placebo but it did not affect ventilation or arterial O2 saturation breathing ambient air at high altitude. Hence, compensatory responses prevent hypoventilation with decreased isocapnic ventilatory O2-sensitivity from ibuprofen at this altitude. The effect of ibuprofen to decrease the HVR in humans provides the first experimental evidence that a signaling mechanism described for ventilatory acclimatization to hypoxia in animal models also occurs in people. This establishes a foundation for the future experiments to test the potential role of different mechanisms for neural plasticity and ventilatory acclimatization in humans with chronic hypoxemia from lung disease. PMID:26726885

Ibuprofen Blunts Ventilatory Acclimatization to Sustained Hypoxia in Humans.

PubMed

Basaran, Kemal Erdem; Villongco, Michael; Ho, Baran; Ellis, Erika; Zarndt, Rachel; Antonova, Julie; Hopkins, Susan R; Powell, Frank L

2016-01-01

Ventilatory acclimatization to hypoxia is a time-dependent increase in ventilation and the hypoxic ventilatory response (HVR) that involves neural plasticity in both carotid body chemoreceptors and brainstem respiratory centers. The mechanisms of such plasticity are not completely understood but recent animal studies show it can be blocked by administering ibuprofen, a nonsteroidal anti-inflammatory drug, during chronic hypoxia. We tested the hypothesis that ibuprofen would also block the increase in HVR with chronic hypoxia in humans in 15 healthy men and women using a double-blind, placebo controlled, cross-over trial. The isocapnic HVR was measured with standard methods in subjects treated with ibuprofen (400 mg every 8 hrs) or placebo for 48 hours at sea level and 48 hours at high altitude (3,800 m). Subjects returned to sea level for at least 30 days prior to repeating the protocol with the opposite treatment. Ibuprofen significantly decreased the HVR after acclimatization to high altitude compared to placebo but it did not affect ventilation or arterial O2 saturation breathing ambient air at high altitude. Hence, compensatory responses prevent hypoventilation with decreased isocapnic ventilatory O2-sensitivity from ibuprofen at this altitude. The effect of ibuprofen to decrease the HVR in humans provides the first experimental evidence that a signaling mechanism described for ventilatory acclimatization to hypoxia in animal models also occurs in people. This establishes a foundation for the future experiments to test the potential role of different mechanisms for neural plasticity and ventilatory acclimatization in humans with chronic hypoxemia from lung disease.

Pilates Method for Lung Function and Functional Capacity in Obese Adults.

PubMed

Niehues, Janaina Rocha; Gonzáles, Inês; Lemos, Robson Rodrigues; Haas, Patrícia

2015-01-01

Obesity is defined as the condition in which the body mass index (BMI) is ≥ 30 kg/m2 and is responsible for decreased quality of life and functional limitations. The harmful effects on ventilatory function include reduced lung capacity and volume; diaphragmatic muscle weakness; decreased lung compliance and stiffness; and weakness of the abdominal muscles, among others. Pilates is a method of resistance training that works with low-impact muscle exercises and is based on isometric exercises. The current article is a review of the literature that aims to investigate the hypothesis that the Pilates method, as a complementary method of training, might be beneficial to pulmonary function and functional capacity in obese adults. The intent of the review was to evaluate the use of Pilates as an innovative intervention in the respiratory dysfunctions of obese adults. In studies with other populations, it has been observed that Pilates can be effective in improving chest capacity and expansion and lung volume. That finding is due to the fact that Pilates works through the center of force, made ​​up of the abdominal muscles and gluteus muscles lumbar, which are responsible for the stabilization of the static and dynamic body that is associated with breath control. It has been observed that different Pilates exercises increase the activation and recruitment of the abdominal muscles. Those muscles are important in respiration, both in expiration and inspiration, through the facilitation of diaphragmatic action. In that way, strengthening the abdominal muscles can help improve respiratory function, leading to improvements in lung volume and capacity. The results found in the current literature review support the authors' observations that Pilates promotes the strengthening of the abdominal muscles and that improvements in diaphragmatic function may result in positive outcomes in respiratory function, thereby improving functional capacity. However, the authors did not find specific studies with obese people, justifying the need for future studies.

Pectus excavatum in children: pulmonary scintigraphy before and after corrective surgery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blickman, J.G.; Rosen, P.R.; Welch, K.J.

1985-09-01

Regional distribution of pulmonary function was evaluated preoperatively and postoperatively with xenon-133 perfusion and ventilation scintigraphy in 17 patients with pectus excavatum. Ventilatory preoperative studies were abnormal in 12 of 17 patients, resolving in seven of 12 postoperatively. Perfusion scans were abnormal in ten of 17 patients preoperatively; six of ten showed improvement postoperatively. Ventilation-perfusion ratios were abnormal in ten of 17 patients, normalizing postoperatively in six of ten. Symmetry of ventilation-perfusion ratio images improved in six out of nine in the latter group. The distribution of regional lung function in pectus excavatum can be evaluated preoperatively to support indicationsmore » for surgery. Postoperative improvement can be documented by physiological changes produced by the surgical correction.« less

20 CFR 410.430 - Ventilatory studies.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Ventilatory studies. 410.430 Section 410.430... studies. Spirometric tests to measure ventilatory function must be expressed in liters or liters per... least 20 millimeters (mm.) per second. The height of the individual must be recorded. Studies should not...

20 CFR 410.430 - Ventilatory studies.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 20 Employees' Benefits 2 2011-04-01 2011-04-01 false Ventilatory studies. 410.430 Section 410.430... studies. Spirometric tests to measure ventilatory function must be expressed in liters or liters per... least 20 millimeters (mm.) per second. The height of the individual must be recorded. Studies should not...

Response of the oxygen uptake efficiency slope to orthotopic heart transplantation: lack of correlation with changes in central hemodynamic parameters and resting lung function.

PubMed

Van Laethem, Christophe; Goethals, Marc; Verstreken, Sofie; Walravens, Maarten; Wellens, Francis; De Proft, Margot; Bartunek, Jozef; Vanderheyden, Marc

2007-09-01

Recently, a new linear measure of ventilatory response to exercise, the oxygen uptake efficiency slope (OUES), was proposed in the evaluation of heart failure patients. No data are available on the response of the OUES after orthotopic heart transplantation (HTx). Thirty patients who underwent HTx between 1999 and 2003 were included in the study. Data from maximal cardiopulmonary exercise test, resting pulmonary function and hemodynamic assessment were collected before the transplant at time of screening and 1 year after HTx. During the first year after HTx, OUES and normalized OUES for body weight (OUES/kg) increased significantly from 15.6 +/- 4.9 to 19.7 +/- 4.8 (p < 0.05). Changes in OUES/kg were significantly correlated with changes in peak VO2, VAT and peak VE, and inversely to changes in peak VD/VT, but not to changes in VE/VCO2 slope (all p < 0.05). Changes in OUES or OUES/kg did not correlate with any changes in measures of resting lung volumes or capacities and measures of central hemodynamic function after HTx. OUES improved significantly after HTx, but, similar to other exercise parameters, remained considerably impaired. The changes in OUES were highly correlated with the improvements in other exercise variables, but did not correlate with marked improvements in central hemodynamics or resting lung function.

Physiological Requirements to Perform the Glittre Activities of Daily Living Test by Subjects With Mild-to-Severe COPD.

PubMed

Souza, Gérson F; Moreira, Graciane L; Tufanin, Andréa; Gazzotti, Mariana R; Castro, Antonio A; Jardim, José R; Nascimento, Oliver A

2017-08-01

The Glittre activities of daily living (ADL) test is supposed to evaluate the functional capacity of COPD patients. The physiological requirements of the test and the time taken to perform it by COPD patients in different disease stages are not well known. The objective of this work was to compare the metabolic, ventilatory, and cardiac requirements and the time taken to carry out the Glittre ADL test by COPD subjects with mild, moderate, and severe disease. Spirometry, Medical Research Council questionnaire, cardiopulmonary exercise test, and 2 Glittre ADL tests were evaluated in 62 COPD subjects. Oxygen uptake (V̇ O 2 ), carbon dioxide production, pulmonary ventilation, breathing frequency, heart rate, S pO 2 , and dyspnea were analyzed before and at the end of the tests. Maximum voluntary ventilation, Glittre peak V̇ O 2 /cardiopulmonary exercise test (CPET) peak V̇ O 2 , Glittre V̇ E /maximum voluntary ventilation, and Glittre peak heart rate/CPET peak heart rate ratios were calculated to analyze their reserves. Subjects carried out the Glittre ADL test with similar absolute metabolic, ventilatory, and cardiac requirements. Ventilatory reserve decreased progressively from mild to severe COPD subjects ( P < .001 for Global Initiative for Chronic Obstructive Lung Disease [GOLD] 1 vs GOLD 2, P < .001 for GOLD 1 vs GOLD 3, and P < .001 for GOLD 2 vs GOLD 3). Severe subjects with COPD presented a significantly lower metabolic reserve than the mild and moderate subjects ( P = .006 and P = .043, respectively) and significantly lower Glittre peak heart rate/CPET peak heart rate than mild subjects ( P = .01). Time taken to carry out the Glittre ADL test was similar among the groups ( P = .82 for GOLD 1 vs GOLD 2, P = .19 for GOLD 1 vs GOLD 3, and P = .45 for GOLD 2 vs GOLD 3). As the degree of air-flow obstruction progresses, the COPD subjects present significant lower ventilatory reserve to perform the Glittre ADL test. In addition, metabolic and cardiac reserves may differentiate the severe subjects. These variables may be better measures to differentiate functional performance than Glittre ADL time. Copyright © 2017 by Daedalus Enterprises.

[Pathophysiology of respiratory muscle weakness].

PubMed

Windisch, W

2008-03-01

The respiratory system consists of two parts which can be impaired independently from each other, the lungs and the respiratory pump. The latter is a complex system covering different anatomic structures: the breathing centre, the peripheral nervous system, the respiratory muscles, and the thorax. According to this complexity several underlying conditions can cause insufficiency of the respiratory pump, i. e. ventilatory failure. Disturbances of the breathing centre, different neuromuscular disorders, impairments of the mechanics, such as thoracic deformities or hyperinflation, and airway obstruction are example conditions responsible for ventilatory failure. Main characteristic of ventilatory failure is the occurrence of hypercapnia which is in contrast to pulmonary failure where diffusion disturbances typically not cause hypercapnia. Both acute and chronic ventilatory failure presenting with hypercapnia can develop. In acute ventilatory failure respiratory acidosis develops, but in chronic respiratory failure pH is normalized as a consequence of metabolic retention of bicarbonate. However, acute on chronic ventilatory failure can present with a combined picture, i. e. elevated bicarbonate levels, acidosis, and often severe hypercapnia. Clinical signs such as tachypnea, features of the underlying disease or hypercapnia are important diagnostic tools in addition to the measurement of pressures generated by the respiratory muscles. Non-invasive and widely available techniques, such as the assessment of the maximal ins- and expiratory mouth pressures (PImax, PEmax), should be used as screening instruments, but the reliability of these measurements is reduced due to the volitional character of the tests and due to the impossibility to define normal values. Inspiratory pressures can be assessed more accurately and independently from the patients' effort: with or without the insertion of oesophageal and gastric balloon catheters. However, this technique is more invasive and very complex. It is therefore restricted to centres with scientific aims.

Pulmonary physiology during pulmonary embolism.

PubMed

Elliott, C G

1992-04-01

Acute pulmonary thromboembolism produces a number of pathophysiologic derangements of pulmonary function. Foremost among these alterations is increased pulmonary vascular resistance. For patients without preexistent cardiopulmonary disease, increased pulmonary vascular resistance is directly related to the degree of vascular obstruction demonstrated on the pulmonary arteriogram. Vasoconstriction, either reflexly or biochemically mediated, may contribute to increased pulmonary vascular resistance. Acute pulmonary thromboembolism also disturbs matching of ventilation and blood flow. Consequently, some lung units are overventilated relative to perfusion (increased dead space), while other lung units are underventilated relative to perfusion (venous admixture). True right-to-left shunting of mixed venous blood can occur through the lungs (intrapulmonary shunt) or across the atrial septum (intracardiac shunt). In addition, abnormalities of pulmonary gas exchange (carbon monoxide transfer), pulmonary compliance and airway resistance, and ventilatory control may accompany pulmonary embolism. Thrombolytic therapy can reverse the hemodynamic derangements of acute pulmonary thromboembolism more rapidly than anticoagulant therapy. Limited data suggest a sustained benefit of thrombolytic treatment on the pathophysiologic alterations of pulmonary vascular resistance and pulmonary gas exchange produced by acute pulmonary emboli.

Exertional dyspnea associated with chest wall strapping is reduced when external dead space substitutes for part of the exercise stimulus to ventilation.

PubMed

Garske, Luke A; Lal, Ravin; Stewart, Ian B; Morris, Norman R; Cross, Troy J; Adams, Lewis

2017-05-01

Chest wall strapping has been used to assess mechanisms of dyspnea with restrictive lung disease. This study examined the hypothesis that dyspnea with restriction depends principally on the degree of reflex ventilatory stimulation. We compared dyspnea at the same (iso)ventilation when added dead space provided a component of the ventilatory stimulus during exercise. Eleven healthy men undertook a randomized controlled crossover trial that compared four constant work exercise conditions: 1 ) control (CTRL): unrestricted breathing at 90% gas exchange threshold (GET); 2 ) CTRL+dead space (DS): unrestricted breathing with 0.6-l dead space, at isoventilation to CTRL due to reduced exercise intensity; 3 ) CWS: chest wall strapping at 90% GET; and 4 ) CWS+DS: chest strapping with 0.6-l dead space, at isoventilation to CWS with reduced exercise intensity. Chest strapping reduced forced vital capacity by 30.4 ± 2.2% (mean ± SE). Dyspnea at isoventilation was unchanged with CTRL+DS compared with CTRL (1.93 ± 0.49 and 2.17 ± 0.43, 0-10 numeric rating scale, respectively; P = 0.244). Dyspnea was lower with CWS+DS compared with CWS (3.40 ± 0.52 and 4.51 ± 0.53, respectively; P = 0.003). Perceived leg fatigue was reduced with CTRL+DS compared with CTRL (2.36 ± 0.48 and 2.86 ± 0.59, respectively; P = 0.049) and lower with CWS+DS compared with CWS (1.86 ± 0.30 and 4.00 ± 0.79, respectively; P = 0.006). With unrestricted breathing, dead space did not change dyspnea at isoventilation, suggesting that dyspnea does not depend on the mode of reflex ventilatory stimulation in healthy individuals. With chest strapping, dead space presented a less potent stimulus to dyspnea, raising the possibility that leg muscle work contributes to dyspnea perception independent of the ventilatory stimulus. NEW & NOTEWORTHY Chest wall strapping was applied to healthy humans to simulate restrictive lung disease. With chest wall strapping, dyspnea was reduced when dead space substituted for part of a constant exercise stimulus to ventilation. Dyspnea associated with chest wall strapping depended on the contribution of leg muscle work to ventilatory stimulation. Chest wall strapping might not be a clinically relevant model to determine whether an alternative reflex ventilatory stimulus mimics the intensity of exertional dyspnea. Copyright © 2017 the American Physiological Society.

Lack of phosphoinositide 3-kinase-gamma attenuates ventilator-induced lung injury.

PubMed

Lionetti, Vincenzo; Lisi, Alberto; Patrucco, Enrico; De Giuli, Paolo; Milazzo, Maria Giovanna; Ceci, Simone; Wymann, Matthias; Lena, Annalisa; Gremigni, Vittorio; Fanelli, Vito; Hirsch, Emilio; Ranieri, V Marco

2006-01-01

G protein-coupled receptors may up-regulate the inflammatory response elicited by ventilator-induced lung injury but also regulate cell survival via protein kinase B (Akt) and extracellular signal regulated kinases 1/2 (ERK1/2). The G protein-sensitive phosphoinositide-3-kinase gamma (PI3Kgamma) regulates several cellular functions including inflammation and cell survival. We explored the role of PI3Kgamma on ventilator-induced lung injury. Prospective, randomized, experimental study. University animal research laboratory. Wild-type (PI3Kgamma), knock-out (PI3Kgamma ), and kinase-dead (PI3Kgamma) mice. Three ventilatory strategies (no stretch, low stretch, high stretch) were studied in an isolated, nonperfused model of acute lung injury (lung lavage) in PI3Kgamma, PI3Kgamma, and PI3Kgamma mice. Reduction in lung compliance, hyaline membrane formation, and epithelial detachment with high stretch were more pronounced in PI3Kgamma than in PI3Kgamma and PI3Kgamma (p < .01). Inflammatory cytokines and IkBalpha phosphorylation with high stretch did not differ among PI3Kgamma, PI3Kgamma, and PI3Kgamma. Apoptotic index (terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick-end labeling) and caspase-3 (immunohistochemistry) with high stretch were larger (p < .01) in PI3Kgamma and PI3Kgamma than in PI3Kgamma. Electron microscopy showed that high stretch caused apoptotic changes in alveolar cells of PI3Kgamma mice whereas PI3Kgamma mice showed necrosis. Phosphorylation of Akt and ERK1/2 with high stretch was more pronounced in PI3Kgamma than in PI3Kgamma and PI3Kgamma (p < .01). Silencing PI3Kgamma seems to attenuate functional and morphological consequences of ventilator-induced lung injury independently of inhibitory effects on cytokines release but through the enhancement of pulmonary apoptosis.

Effects of air pollution and seasons on health-related quality of life of Mongolian adults living in Ulaanbaatar: cross-sectional studies.

PubMed

Nakao, Motoyuki; Yamauchi, Keiko; Ishihara, Yoko; Omori, Hisamitsu; Ichinnorov, Dashtseren; Solongo, Bandi

2017-06-23

Ulaanbaatar, Mongolia, is known as severely air-polluted city in the world due to increased coal consumption in the cold season. The health effects of air pollution in Mongolia such as mortality, morbidity and symptoms have been previously reported. However, the concept of health-related quality of life (HR-QoL), which refers to the individual's perception of well-being, should also be included as an adverse health outcome of air pollution. Surveys on the Mongolian people living in Ulaanbaatar were performed in the warm and cold seasons. Self-completed questionnaires on the subjects' HR-QoL, data from health checkups and pulmonary function tests by respiratory specialists were collected for Mongolian adults aged 40-79 years (n = 666). Ambient PM2.5 and PM10 were concurrently sampled and the components were analyzed to estimate the source of air pollution. In logistic regression analyses, respiratory symptoms and smoke-rich fuels were associated with reduced HR-QoL (> 50th percentile vs. ≤ 50th percentile). PM 2.5 levels were much higher in the cold season (median 86.4 μg/m 3 (IQR: 58.7-121.0)) than in the warm season (12.2 μg/m 3 (8.9-21.2). The receptor model revealed that the high PM2.5 concentration in the cold season could be attributed to solid fuel combustion. The difference in HR-QoL between subjects with and without ventilatory impairment was assessed after the stratification of the subjects by season and household fuel type. There were no significant differences in HR-QoL between subjects with and without ventilatory impairment regardless of household fuel type in the warm season. In contrast, subjects with ventilatory impairment who used smoke-rich fuel in the cold season had a significantly lower HR-QoL. Our study showed that air pollution in Ulaanbaatar worsened in the cold season and was estimated to be contributed by solid fuel combustion. Various aspects of HR-QoL in subjects with ventilatory impairment using smoke-rich fuels deteriorated only in the cold season while those with normal lung function did not. These results suggest that countermeasures or interventions by the policymakers to reduce coal usage would improve HR-QoL of the residents of Ulaanbaatar, especially for those with ventilatory impairment in the winter months.

Clinically important FEV1 declines among coal miners: an exploration of previously unrecognised determinants

PubMed Central

Wang, M. L.; Petsonk, E. L.; Beeckman, L. A.; Wagner, G. R.

1999-01-01

OBJECTIVES: The relation between occupational exposure to dust and loss of ventilatory lung function is now well established. However, many exposures during work and other activities might also have important roles in determining clinically important losses of lung function. In this study, we attempted to explore additional plausible determinants of exposures and other potential risk factors for clinically important decline in forced expiratory volume in 1 second (FEV1) during work in dusty trades. METHODS: The study was performed in 264 underground coal miners whose lung function had been followed up for an average of 11 years. With an extensive follow up questionnaire, miners were asked about their occupational and non-occupational exposures, smoking, personal and family medical history, and living conditions during childhood. RESULTS: Several variables of the mine environment (as well as previously recognised effects of mining work and region) were found to be associated with excess decline in FEV1, including work in roof bolting, exposure to explosive blasting, and to control dust spraying water that had been stored in holding tanks. Use of respiratory protection seemed to reduce the risk of decline in FEV1. Other factors that were found to be associated with declines in pulmonary function included smoking, body mass, weight gain, childhood pneumonia, and childhood exposure in the home to passive tobacco smoke and possibly smoke due to wood and coal fuels. Miners with excessive decline in FEV1 were less likely to be working in mining jobs at follow up. CONCLUSIONS: These findings suggest the existence of additional risk factors for decline in lung function in dusty trades, and may be useful in developing additional approaches to the prevention of chronic respiratory disease.   PMID:10658541

Reduced exercise capacity in untreated adults with primary growth hormone resistance (Laron syndrome).

PubMed

Ben-Dov, Issahar; Gaides, Mark; Scheinowitz, Mickey; Wagner, Rivka; Laron, Zvi

2003-12-01

Primary IGF-I deficiency (Laron syndrome, LS) may decrease exercise capacity as a result of a lack of an IGF-I effect on heart, peripheral muscle or lung structure and/or function. Eight patients (six females) who had never received treatment with IGF-I, with mean age of 36 +/- 10 (SD) years (range 21-48), weight 47 +/- 9 kg (31-61), height 126 +/- 12 cm (112-140) and body mass index of 29 +/- 4 kg/m2 (24-34), and 12 age-matched controls, underwent lung function tests and incremental cycling to the limit of tolerance (CPX, MedGraphics). Predicted values for the patients were derived from adult equations based on height. In LS patients, lung function was near normal; vital capacity was 84 +/- 11% of expected (66-103). Peak exercise O2-uptake and the anaerobic threshold were reduced, 57 +/- 20% of predicted and 33 +/- 9% of predicted peak (P = 0.005 vs. controls), despite normal mean exercise breathing reserve. All parameters were normal in the controls. Exercise capacity in untreated adults with LS is significantly reduced. The limitation for most patients was not ventilatory but resulted either from low cardiac output and/or from dysfunction of the peripheral muscles. However, the relative contribution of each of these elements and/or the role of poor fitness needs further study.

Chronic Respiratory Symptoms and Lung Function in Agricultural Workers - Influence of Exposure Duration and Smoking.

PubMed

Stoleski, Saso; Minov, Jordan; Mijakoski, Dragan; Karadzinska-Bislimovska, Jovanka

2015-03-15

Job exposure in agricultural workers often leads to respiratory impairment. To assess the influence of exposure duration and smoking on chronic respiratory symptoms and ventilatory capacity in agricultural workers. A cross-sectional study covered 75 agricultural workers, compared with an equal number of office workers matched by age, exposure duration and smoking status. Standardized questionnaire was used to obtain data on chronic respiratory symptoms, job and smoking history. Lung functional testing was performed by spirometry. The prevalence of respiratory symptoms was higher in agricultural workers, with significant difference for cough (P = 0.034), and dyspnea (P = 0.028). Chronic respiratory symptoms among agricultural workers were significantly associated with duration of exposure (P < 0.05) and daily smoking (P < 0.01), as well as with daily smoking in controls (P < 0.01). The average values of spirometric parameters in exposed workers were significantly different for MEF50 (P = 0.002), MEF75 (P = 0.000), and MEF25-75 (P = 0.049). Obstructive changes in small airways in exposed workers were strongly related to exposure duration (P < 0.05) and smoking (P < 0.01). Agricultural workers with job exposure more than 15 years had more expressed adverse respiratory symptoms and lung function decline. The results confirmed the influence of agricultural exposure and daily smoking on chronic respiratory symptoms and airflow limitation, primarily targeting the small airways.

The rostral medulla of bullfrog tadpoles contains critical lung rhythmogenic and chemosensitive regions across metamorphosis.

PubMed

Reed, Mitchell D; Iceman, Kimberly E; Harris, Michael B; Taylor, Barbara E

2018-06-08

The development of amphibian breathing provides insight into vertebrate respiratory control mechanisms. Neural oscillators in the rostral and caudal medulla drive ventilation in amphibians, and previous reports describe ventilatory oscillators and CO 2 sensitive regions arise during different stages of amphibian metamorphosis. However, inconsistent findings have been enigmatic, and make comparisons to potential mammalian counterparts challenging. In the current study we assessed amphibian central CO 2 responsiveness and respiratory rhythm generation during two different developmental stages. Whole-nerve recordings of respiratory burst activity in cranial and spinal nerves were made from intact or transected brainstems isolated from tadpoles during early or late stages of metamorphosis. Brainstems were transected at the level of the trigeminal nerve, removing rostral structures including the nucleus isthmi, midbrain, and locus coeruleus, or transected at the level of the glossopharyngeal nerve, removing the putative buccal oscillator and caudal medulla. Removal of caudal structures stimulated the frequency of lung ventilatory bursts and revealed a hypercapnic response in normally unresponsive preparations derived from early stage tadpoles. In preparations derived from late stage tadpoles, removal of rostral or caudal structures reduced lung burst frequency, while CO 2 responsiveness was retained. Our results illustrate that structures within the rostral medulla are capable of sensing CO 2 throughout metamorphic development. Similarly, the region controlling lung ventilation appears to be contained in the rostral medulla throughout metamorphosis. This work offers insight into the consistency of rhythmic respiratory and chemosensitive capacities during metamorphosis. Copyright © 2018. Published by Elsevier Inc.

Impact of backpack load on ventilatory function among 9-12 year old Saudi girls.

PubMed

Al-Katheri, Abeer E

2013-12-01

To explore the backpack load as a percentile of body weight (BW) and its impact on ventilatory function including tidal volume (Vt), vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC, peak expiratory flow (PEF), and maximum voluntary ventilation (MVV) among 9-12 year old Saudi girls. This is a prospective, experimental study of 91 Saudi girls aged between 9-12 years from primary schools in Riyadh, Saudi Arabia. The study took place in King Saud University, Riyadh, Saudi Arabia between April 2012 and May 2012. Ventilatory function was measured under 2 conditions: a free standing position without carrying a backpack, and while carrying a backpack. The backpack load observed was 13.8% of the BW, which is greater than the recommended limit (10% BW). All values of ventilatory function were significantly reduced after carrying the backpack (p<0.001) with the exception of FEV1/FVC (p>0.178). The reduction was observed even with the lowest backpack load (7.4% BW). A significant reduction was reported for most of the ventilatory function parameters while carrying the backpack. This reduction was apparent even with the least backpack load (7.4% BW) carried by the participants. This study recommends that the upper safe limit of backpack load carried by Saudi girls aged 9-12 years should be less than 7.4% of BW.

[Ventilatory strategy for ARDS].

PubMed

Yoshida, Takeshi; Takegawa, Ryousuke; Ogura, Hiroshi

2016-02-01

Fifteen years have passed since lung protective strategy to the patients with acute respiratory distress syndrome (ARDS) established. Recently, the new Berlin Definition of ARDS has been developed and this classified ARDS into three stages (mild, moderate, and severe ARDS), depending on the PaO2/FiO2. After this new definition of ARDS, each treatment to the patients with ARDS should be considered, depending on the severity of lung injury, such as prone position to the patients with severe ARDS, muscle paralysis to the patients with severe ARDS. In this review article, we review the history of lung protective strategy and ARDS definition, discuss the novel physiological approaches to minimizing ventilator-induced lung injury, and highlight a numbers of experimental/clinical studies to support these concepts.

Spirometric evaluation of ventilatory function in adult male cigarette smokers in Sokoto metropolis.

PubMed

Isah, Muhammad D; Makusidi, Muhammad A; Abbas, Aminu; Okpapi, Juliana U; Njoku, Chibueze H; Abba, Abdullahi A

2017-01-01

Cigarette smoking is a widespread social habit in Nigeria with extensive deleterious multisystemic effect. Ventilatory dysfunction is one of the cigarette smoking-related illnesses that affect the respiratory system. Spirometry is an investigative method that can be used for the early detection of ventilatory dysfunction even before the onset of the symptoms. A questionnaire adapted from the European Community Respiratory Health Survey was administered to collect demographic, clinical, and cigarette smoking data. Ventilatory function test was conducted using Clement Clarke (One Flow) Spirometer, version 1.3. The highest value of each ventilatory function index was chosen for analysis, and individual(s) with ventilatory dysfunction were subjected to post bronchodilator spirometry. For the purpose of this research, 150 participants who were currently cigarette smokers were enrolled, and 50 apparently healthy, age-matched individuals who were never smokers served as controls in the ratio of 3:1. Eighty percent of participants and 68% of controls were aged 40 years or below. The mean age of participants (34.27 ± 8.91 years) and the controls (35.08 ± 10.35 years) was not significantly different (P = 0.592). Similarly, there were no statistically significant differences between the mean anthropometric indices (weight: P = 0.663, height: P = 0.084, and body mass index: P = 0.099) of both participants and controls. The mean values of FEV1 (forced expiratory flow in one second) and FEV1/FVC (FVC=forced vital capacity) were lower in the participants compared to the controls, and this difference was statistically significant (P < 0.001). There was a weak negative correlation between pack-years of cigarette smoking and FEV1 (r = -0.237 and P = 0.004). Obstructive ventilatory defect was found among six study participants (4%) and two controls (4%). Cigarette smoking is associated with decline in ventilatory function test indices (FEV1 and FEV1/FVC) in adult males. Decline in FEV1 is directly related to pack-years of cigarette smoking.

Positive End-Expiratory Pressure and Variable Ventilation in Lung-Healthy Rats under General Anesthesia

PubMed Central

Camilo, Luciana M.; Ávila, Mariana B.; Cruz, Luis Felipe S.; Ribeiro, Gabriel C. M.; Spieth, Peter M.; Reske, Andreas A.; Amato, Marcelo; Giannella-Neto, Antonio; Zin, Walter A.; Carvalho, Alysson R.

2014-01-01

Objectives Variable ventilation (VV) seems to improve respiratory function in acute lung injury and may be combined with positive end-expiratory pressure (PEEP) in order to protect the lungs even in healthy subjects. We hypothesized that VV in combination with moderate levels of PEEP reduce the deterioration of pulmonary function related to general anesthesia. Hence, we aimed at evaluating the alveolar stability and lung protection of the combination of VV at different PEEP levels. Design Randomized experimental study. Setting Animal research facility. Subjects Forty-nine male Wistar rats (200–270 g). Interventions Animals were ventilated during 2 hours with protective low tidal volume (VT) in volume control ventilation (VCV) or VV and PEEP adjusted at the level of minimum respiratory system elastance (Ers), obtained during a decremental PEEP trial subsequent to a recruitment maneuver, and 2 cmH2O above or below of this level. Measurements and Main Results Ers, gas exchange and hemodynamic variables were measured. Cytokines were determined in lung homogenate and plasma samples and left lung was used for histologic analysis and diffuse alveolar damage scoring. A progressive time-dependent increase in Ers was observed independent on ventilatory mode or PEEP level. Despite of that, the rate of increase of Ers and lung tissue IL-1 beta concentration were significantly lower in VV than in VCV at the level of the PEEP of minimum Ers. A significant increase in lung tissue cytokines (IL-6, IL-1 beta, CINC-1 and TNF-alpha) as well as a ventral to dorsal and cranial to caudal reduction in aeration was observed in all ventilated rats with no significant differences among groups. Conclusions VV combined with PEEP adjusted at the level of the PEEP of minimal Ers seemed to better prevent anesthesia-induced atelectasis and might improve lung protection throughout general anesthesia. PMID:25383882

Ventilatory Function in Relation to Mining Experience and Smoking in a Random Sample of Miners and Non-miners in a Witwatersrand Town1

PubMed Central

Sluis-Cremer, G. K.; Walters, L. G.; Sichel, H. S.

1967-01-01

The ventilatory capacity of a random sample of men over the age of 35 years in the town of Carletonville was estimated by the forced expiratory volume and the peak expiratory flow rate. Five hundred and sixty-two persons were working or had worked in gold-mines and 265 had never worked in gold-mines. No difference in ventilatory function was found between the miners and non-miners other than that due to the excess of chronic bronchitis in miners. PMID:6017134

LONG TERM EFFECTS OF PRENATAL AND POSTNATAL AIRBORNE PAH EXPOSURE ON VENTILATORY LUNG FUNCTION OF NON-ASTHMATIC PREADOLESCENT CHILDREN. PROSPECTIVE BIRTH COHORT STUDY IN KRAKOW

PubMed Central

Jedrychowski, Wieslaw A.; Perera, Frederica P.; Maugeri, Umberto; Majewska, Renata; Mroz, Elzbieta; Flak, Elzbieta; Camman, David; Sowa, Agata; Jacek, Ryszard

2014-01-01

The main goal of the study was to test the hypothesis that prenatal and postnatal exposure to polycyclic aromatic hydrocarbons (PAH) is associated with depressed lung function in non-asthmatic children. The study sample comprises 195 non-asthmatic children of non-smoking mothers, among whom the prenatal PAH exposure was assessed by personal air monitoring in pregnancy. At the age of 3, residential air monitoring was carried out to evaluate the residential PAH exposure indoors and outdoors. At the age of 5 to 8, children were given allergic skin tests for indoor allergens; and between 5–9 years lung function testing (FVC, FEV05, FEV1 and FEF25–75) was performed. The effects of prenatal PAH exposure on lung function tests repeated over the follow-up were adjusted in the General Estimated Equation (GEE) model for the relevant covariates. No association between FVC with prenatal PAH exposure was found; however for the FEV1 deficit associated with higher prenatal PAH exposure (above 37ng/m3) amounted to 53 mL (p = 0.050) and the deficit of FEF25–75 reached 164 mL (p=0.013). The corresponding deficits related to postnatal residential indoor PAH level (above 42 ng/m3) were 59 mL of FEV1 (p=0.028) and 140 mL of FEF25–75 (p=0.031). At the higher residential outdoor PAH level (above 90 ng/m3) slightly greater deficit of FEV1 (71mL, p = 0.009) was observed. The results of the study suggest that transplacental exposure to PAH compromises the normal developmental process of respiratory airways and that this effect is compounded by postnatal PAH exposure. PMID:25300014

Lung-Kidney Cross-Talk in the Critically Ill Patient.

PubMed

Husain-Syed, Faeq; Slutsky, Arthur S; Ronco, Claudio

2016-08-15

Discoveries have emerged highlighting the complex nature of the interorgan cross-talk between the kidney and the lung. Vascular rigidity, neurohormonal activation, tissue hypoxia, and abnormal immune cell signaling have been identified as common pathways leading to the development and progression of chronic kidney disease. However, our understanding of the causal relationships between lung injury and kidney injury is not precise. This review discusses a number of features and mechanisms of renal dysfunction in pulmonary disorders in relation to respiratory acidosis, impaired gas exchange, systemic congestion, respiratory support/replacement therapies, and other issues relevant to the clinical care of these patients. Biotrauma due to injurious ventilatory strategies can lead to the release of mediators into the lung, which may then translocate into the systemic circulation and cause end-organ dysfunction, including renal dysfunction. Right ventricular dysfunction and congestive states may contribute to alterations of renal perfusion and oxygenation, leading to diuretic resistance and recurrent hospitalization. In patients with concomitant respiratory failure, noninvasive ventilation represents a promising treatment option for the correction of impaired renal microcirculation and endothelial dysfunction. In patients requiring extracorporeal membrane oxygenation, short- and long-term monitoring of kidney function is warranted, as they are at highest risk of developing acute kidney injury and fluid overload.

Humidification during high-frequency oscillation ventilation is affected by ventilator circuit and ventilatory setting.

PubMed

Chikata, Yusuke; Imanaka, Hideaki; Onishi, Yoshiaki; Ueta, Masahiko; Nishimura, Masaji

2009-08-01

High-frequency oscillation ventilation (HFOV) is an accepted ventilatory mode for acute respiratory failure in neonates. As conventional mechanical ventilation, inspiratory gas humidification is essential. However, humidification during HFOV has not been clarified. In this bench study, we evaluated humidification during HFOV in the open circumstance of ICU. Our hypothesis is that humidification during HFOV is affected by circuit design and ventilatory settings. We connected a ventilator with HFOV mode to a neonatal lung model that was placed in an infant incubator set at 37 degrees C. We set a heated humidifier (Fisher & Paykel) to obtain 37 degrees C at the chamber outlet and 40 degrees C at the distal temperature probe. We measured absolute humidity and temperature at the Y-piece using a rapid-response hygrometer. We evaluated two types of ventilator circuit: a circuit with inner heating wire and another with embedded heating element. In addition, we evaluated three lengths of the inspiratory limb, three stroke volumes, three frequencies, and three mean airway pressures. The circuit with embedded heating element provided significantly higher absolute humidity and temperature than one with inner heating wire. As an extended tube lacking a heating wire was shorter, absolute humidity and temperature became higher. In the circuit with inner heating wire, absolute humidity and temperature increased as stroke volume increased. Humidification during HFOV is affected by circuit design and ventilatory settings.

Predicted equations for ventilatory function among Kuching (Sarawak, Malaysia) population.

PubMed

Djojodibroto, R D; Pratibha, G; Kamaluddin, B; Manjit, S S; Sumitabha, G; Kumar, A Deva; Hashami, B

2009-12-01

Spirometry data of 869 individuals (males and females) between the ages of 10 to 60 years were analyzed. The analysis yielded the following conclusions: 1. The pattern of Forced Vital Capacity (FVC) and Forced Expiratory Volume in One Second (FEV1) for the selected subgroups seems to be gender dependant: in males, the highest values were seen in the Chinese, followed by the Malay, and then the Dayak; in females, the highest values were seen in the Chinese, followed by the Dayak, and then the Malay. 2. Smoking that did not produce respiratory symptom was not associated with a decline in lung function, in fact we noted higher values in smokers as compared to nonsmokers. 3. Prediction formulae (54 in total) are worked out for FVC & FEV1 for the respective gender and each of the selected subgroups.

[Aging of the respiratory system: anatomical changes and physiological consequences].

PubMed

Ketata, W; Rekik, W K; Ayadi, H; Kammoun, S

2012-10-01

The respiratory system undergoes progressive involution with age, resulting in anatomical and functional changes that are exerted on all levels. The rib cage stiffens and respiratory muscles weaken. Distal bronchioles have reduced diameter and tend to be collapsed. Mobilized lung volumes decrease with age while residual volume increases. Gas exchanges are modified with a linear decrease of PaO(2) up to the age of 70 years and a decreased diffusing capacity of carbon monoxide. Ventilatory responses to hypercapnia, hypoxia and exercise decrease in the elderly. Knowledge of changes in the respiratory system related to advancing age is a medical issue of great importance in order to distinguish the effects of aging from those of diseases. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Open lung approach versus standard protective strategies: Effects on driving pressure and ventilatory efficiency during anesthesia - A pilot, randomized controlled trial.

PubMed

Ferrando, Carlos; Suarez-Sipmann, Fernando; Tusman, Gerardo; León, Irene; Romero, Esther; Gracia, Estefania; Mugarra, Ana; Arocas, Blanca; Pozo, Natividad; Soro, Marina; Belda, Francisco J

2017-01-01

Low tidal volume (VT) during anesthesia minimizes lung injury but may be associated to a decrease in functional lung volume impairing lung mechanics and efficiency. Lung recruitment (RM) can restore lung volume but this may critically depend on the post-RM selected PEEP. This study was a randomized, two parallel arm, open study whose primary outcome was to compare the effects on driving pressure of adding a RM to low-VT ventilation, with or without an individualized post-RM PEEP in patients without known previous lung disease during anesthesia. Consecutive patients scheduled for major abdominal surgery were submitted to low-VT ventilation (6 ml·kg-1) and standard PEEP of 5 cmH2O (pre-RM, n = 36). After 30 min estabilization all patients received a RM and were randomly allocated to either continue with the same PEEP (RM-5 group, n = 18) or to an individualized open-lung PEEP (OL-PEEP) (Open Lung Approach, OLA group, n = 18) defined as the level resulting in maximal Cdyn during a decremental PEEP trial. We compared the effects on driving pressure and lung efficiency measured by volumetric capnography. OL-PEEP was found at 8±2 cmH2O. 36 patients were included in the final analysis. When compared with pre-RM, OLA resulted in a 22% increase in compliance and a 28% decrease in driving pressure when compared to pre-RM. These parameters did not improve in the RM-5. The trend of the DP was significantly different between the OLA and RM-5 groups (p = 0.002). VDalv/VTalv was significantly lower in the OLA group after the RM (p = 0.035). Lung recruitment applied during low-VT ventilation improves driving pressure and lung efficiency only when applied as an open-lung strategy with an individualized PEEP in patients without lung diseases undergoing major abdominal surgery. ClinicalTrials.gov NCT02798133.

Management of mechanical ventilation during laparoscopic surgery.

PubMed

Valenza, Franco; Chevallard, Giorgio; Fossali, Tommaso; Salice, Valentina; Pizzocri, Marta; Gattinoni, Luciano

2010-06-01

Laparoscopy is widely used in the surgical treatment of a number of diseases. Its advantages are generally believed to lie on its minimal invasiveness, better cosmetic outcome and shorter length of hospital stay based on surgical expertise and state-of-the-art equipment. Thousands of laparoscopic surgical procedures performed safely prove that mechanical ventilation during anaesthesia for laparoscopy is well tolerated by a vast majority of patients. However, the effects of pneumoperitoneum are particularly relevant to patients with underlying lung disease as well as to the increasing number of patients with higher-than-normal body mass index. Moreover, many surgical procedures are significantly longer in duration when performed with laparoscopic techniques. Taken together, these factors impose special care for the management of mechanical ventilation during laparoscopic surgery. The purpose of the review is to summarise the consequences of pneumoperitoneum on the standard monitoring of mechanical ventilation during anaesthesia and to discuss the rationale of using a protective ventilation strategy during laparoscopic surgery. The consequences of chest wall derangement occurring during pneumoperitoneum on airway pressure and central venous pressure, together with the role of end-tidal-CO2 monitoring are emphasised. Ventilatory and non-ventilatory strategies to protect the lung are discussed.

Small Airway Dysfunction and Abnormal Exercise Responses

PubMed Central

Petsonk, Edward L.; Stansbury, Robert C.; Beeckman-Wagner, Lu-Ann; Long, Joshua L.; Wang, Mei Lin

2016-01-01

Rationale Coal mine dust exposure can cause symptoms and loss of lung function from multiple mechanisms, but the roles of each disease process are not fully understood. Objectives We investigated the implications of small airway dysfunction for exercise physiology among a group of workers exposed to coal mine dust. Methods Twenty coal miners performed spirometry, first breathing air and then helium-oxygen, single-breath diffusing capacity, and computerized chest tomography, and then completed cardiopulmonary exercise testing. Measurements and Main Results Six participants meeting criteria for small airway dysfunction were compared with 14 coal miners who did not. At submaximal workload, miners with small airway dysfunction used a higher proportion of their maximum voluntary ventilation and had higher ventilatory equivalents for both O2 and CO2. Regression modeling indicated that inefficient ventilation was significantly related to small airway dysfunction but not to FEV1 or diffusing capacity. At the end of exercise, miners with small airway dysfunction had 27% lower O2 consumption. Conclusions Small airway abnormalities may be associated with important inefficiency of exercise ventilation. In dust-exposed individuals with only mild abnormalities on resting lung function tests or chest radiographs, cardiopulmonary exercise testing may be important in defining causes of exercise intolerance. PMID:27073987

Effects of intracerebroventricular administered fluoxetine on cardio-ventilatory functions in rainbow trout (Oncorhynchus mykiss).

PubMed

Kermorgant, Marc; Lancien, Frédéric; Mimassi, Nagi; Tyler, Charles R; Le Mével, Jean-Claude

2014-09-01

Fluoxetine (FLX) is a selective serotonin (5-HT) reuptake inhibitor present in the aquatic environment which is known to bioconcentrate in the brains of exposed fish. FLX acts as a disruptor of various neuroendocrine functions in the brain, but nothing is known about the possible consequence of FLX exposure on the cardio-ventilatory system in fish. Here we undertook to investigate the central actions of FLX on ventilatory and cardiovascular function in unanesthetized rainbow trout (Oncorhynchus mykiss). Intracerebroventricular (ICV) injection of FLX (dosed between 5 and 25 μg) resulted in a significantly elevated total ventilation (VTOT), with a maximum hyperventilation of +176% (at a dose of 25μg) compared with vehicle injected controls. This increase was due to an increase in ventilatory amplitude (VAMP: +126%) with minor effects on ventilatory frequency. The highest dose of FLX (25 μg) produced a significant increase in mean dorsal aortic blood pressure (PDA: +20%) without effects on heart rate (ƒH). In comparison, intra-arterial injections of FLX (500-2,500 μg) had no effect on ventilation but the highest doses increased both PDA and ƒH. The ICV and IA cardio-ventilatory effects of FLX were very similar to those previously observed following injections of 5-HT, indicating that FLX probably acts via stimulating endogenous 5-HT activity through inhibition of 5-HT transporter(s). Our results demonstrate for the first time in fish that FLX administered within the brain exerts potent stimulatory effects on ventilation and blood pressure increase. The doses of FLX given to fish in our study are higher than the brain concentrations of FLX in fish that result from acute exposure to FLX through the water. Nonetheless, our results indicate possible disrupting action of long term exposure to FLX discharged into the environment on central target sites sensitive to 5-HT involved in cardio-ventilatory control. Copyright © 2013 Elsevier Inc. All rights reserved.

[Lung protective ventilation - pathophysiology and diagnostics].

PubMed

Uhlig, Stefan; Frerichs, Inéz

2008-06-01

Mechanical ventilation may lead to lung injury depending on the ventilatory settings (e.g. pressure amplitudes, endexpiratory pressures, frequency) and the length of mechanical ventilation. Particularly in the inhomogeneously injured lungs of ARDS patients, alveolar overextension results in volutrauma, cyclic opening and closure of alveolar units in atelectrauma. Particularly important appears to be the fact that these processes may also cause biotrauma, i.e. the ventilator-induced hyperactivation of inflammatory responses in the lung. These side effects are reduced, but not eliminated with the currently recommended ventilation strategy with a tidal volume of 6 ml/kg idealized body weight. It is our hope that in the future optimization of ventilator settings will be facilated by bedside monitoring of novel indices of respiratory mechanics such as the stress index or the Slice technique, and by innovative real-time imaging technologies such as electrical impedance tomography.

Effects of aerial hypoxia and temperature on pulmonary breathing pattern and gas exchange in the South American lungfish, Lepidosiren paradoxa.

PubMed

da Silva, Glauber S F; Ventura, Daniela A D N; Zena, Lucas A; Giusti, Humberto; Glass, Mogens L; Klein, Wilfried

2017-05-01

The South American lungfish Lepidosiren paradoxa is an obligatory air-breathing fish possessing well-developed bilateral lungs, and undergoing seasonal changes in its habitat, including temperature changes. In the present study we aimed to evaluate gas exchange and pulmonary breathing pattern in L. paradoxa at different temperatures (25 and 30°C) and different inspired O 2 levels (21, 12, 10, and 7%). Normoxic breathing pattern consisted of isolated ventilatory cycles composed of an expiration followed by 2.4±0.2 buccal inspirations. Both expiratory and inspiratory tidal volumes reached a maximum of about 35mlkg -1 , indicating that L. paradoxa is able to exchange nearly all of its lung air in a single ventilatory cycle. At both temperatures, hypoxia caused a significant increase in pulmonary ventilation (V̇ E ), mainly due to an increase in respiratory frequency. Durations of the ventilatory cycle and expiratory and inspiratory tidal volumes were not significantly affected by hypoxia. Expiratory time (but not inspiratory) was significantly shorter at 30°C and at all O 2 levels. While a small change in oxygen consumption (V̇O 2 ) could be noticed, the carbon dioxide release (V̇CO 2 , P=0.0003) and air convection requirement (V̇ E /V̇O 2 , P=0.0001) were significantly affected by hypoxia (7% O 2 ) at both temperatures, when compared to normoxia, and pulmonary diffusion capacity increased about four-fold due to hypoxic exposure. These data highlight important features of the respiratory system of L. paradoxa, capable of matching O 2 demand and supply under different environmental change, as well as help to understand the evolution of air breathing in lungfish. Copyright © 2017 Elsevier Inc. All rights reserved.

Effects of maturation and acidosis on the chaos-like complexity of the neural respiratory output in the isolated brainstem of the tadpole, Rana esculenta

PubMed Central

Samara, Ziyad; Fiamma, Marie-Noëlle; Bautin, Nathalie; Ranohavimparany, Anja; Le Coz, Patrick; Golmard, Jean-Louis; Darré, Pierre; Zelter, Marc; Poon, Chi-Sang; Similowski, Thomas

2011-01-01

Human ventilation at rest exhibits mathematical chaos-like complexity that can be described as long-term unpredictability mediated (in whole or in part) by some low-dimensional nonlinear deterministic process. Although various physiological and pathological situations can affect respiratory complexity, the underlying mechanisms remain incompletely elucidated. If such chaos-like complexity is an intrinsic property of central respiratory generators, it should appear or increase when these structures mature or are stimulated. To test this hypothesis, we employed the isolated tadpole brainstem model [Rana (Pelophylax) esculenta] and recorded the neural respiratory output (buccal and lung rhythms) of pre- (n = 8) and postmetamorphic tadpoles (n = 8), at physiologic (7.8) and acidic pH (7.4). We analyzed the root mean square of the cranial nerve V or VII neurograms. Development and acidosis had no effect on buccal period. Lung frequency increased with development (P < 0.0001). It also increased with acidosis, but in postmetamorphic tadpoles only (P < 0.05). The noise-titration technique evidenced low-dimensional nonlinearities in all the postmetamorphic brainstems, at both pH. Chaos-like complexity, assessed through the noise limit, increased from pH 7.8 to pH 7.4 (P < 0.01). In contrast, linear models best fitted the ventilatory rhythm in all but one of the premetamorphic preparations at pH 7.8 (P < 0.005 vs. postmetamorphic) and in four at pH 7.4 (not significant vs. postmetamorphic). Therefore, in a lower vertebrate model, the brainstem respiratory central rhythm generator accounts for ventilatory chaos-like complexity, especially in the postmetamorphic stage and at low pH. According to the ventilatory generators homology theory, this may also be the case in mammals. PMID:21325645

Effects of maturation and acidosis on the chaos-like complexity of the neural respiratory output in the isolated brainstem of the tadpole, Rana esculenta.

PubMed

Straus, Christian; Samara, Ziyad; Fiamma, Marie-Noëlle; Bautin, Nathalie; Ranohavimparany, Anja; Le Coz, Patrick; Golmard, Jean-Louis; Darré, Pierre; Zelter, Marc; Poon, Chi-Sang; Similowski, Thomas

2011-05-01

Human ventilation at rest exhibits mathematical chaos-like complexity that can be described as long-term unpredictability mediated (in whole or in part) by some low-dimensional nonlinear deterministic process. Although various physiological and pathological situations can affect respiratory complexity, the underlying mechanisms remain incompletely elucidated. If such chaos-like complexity is an intrinsic property of central respiratory generators, it should appear or increase when these structures mature or are stimulated. To test this hypothesis, we employed the isolated tadpole brainstem model [Rana (Pelophylax) esculenta] and recorded the neural respiratory output (buccal and lung rhythms) of pre- (n = 8) and postmetamorphic tadpoles (n = 8), at physiologic (7.8) and acidic pH (7.4). We analyzed the root mean square of the cranial nerve V or VII neurograms. Development and acidosis had no effect on buccal period. Lung frequency increased with development (P < 0.0001). It also increased with acidosis, but in postmetamorphic tadpoles only (P < 0.05). The noise-titration technique evidenced low-dimensional nonlinearities in all the postmetamorphic brainstems, at both pH. Chaos-like complexity, assessed through the noise limit, increased from pH 7.8 to pH 7.4 (P < 0.01). In contrast, linear models best fitted the ventilatory rhythm in all but one of the premetamorphic preparations at pH 7.8 (P < 0.005 vs. postmetamorphic) and in four at pH 7.4 (not significant vs. postmetamorphic). Therefore, in a lower vertebrate model, the brainstem respiratory central rhythm generator accounts for ventilatory chaos-like complexity, especially in the postmetamorphic stage and at low pH. According to the ventilatory generators homology theory, this may also be the case in mammals.

Organophosphate-induced intermediate syndrome: aetiology and relationships with myopathy.

PubMed

Karalliedde, Lakshman; Baker, David; Marrs, Timothy C

2006-01-01

The intermediate syndrome (IMS) following organophosphorus (OP) insecticide poisoning was first described in the mid-1980s. The syndrome described comprised characteristic symptoms and signs occurring after apparent recovery from the acute cholinergic syndrome. As the syndrome occurred after the acute cholinergic syndrome but before organophosphate-induced delayed polyneuropathy, the syndrome was called 'intermediate syndrome'. The IMS occurs in approximately 20% of patients following oral exposure to OP pesticides, with no clear association between the particular OP pesticide involved and the development of the syndrome. It usually becomes established 2-4 days after exposure when the symptoms and signs of the acute cholinergic syndrome (e.g. muscle fasciculations, muscarinic signs) are no longer obvious. The characteristic features of the IMS are weakness of the muscles of respiration (diaphragm, intercostal muscles and accessory muscles including neck muscles) and of proximal limb muscles. Accompanying features often include weakness of muscles innervated by some cranial nerves. It is now emerging that the degree and extent of muscle weakness may vary following the onset of the IMS. Thus, some patients may only have weakness of neck muscles whilst others may have weakness of neck muscles and proximal limb muscles. These patients may not require ventilatory care but close observation and monitoring of respiratory function is mandatory. Management is essentially that of rapidly developing respiratory distress and respiratory failure. Delays in instituting ventilatory care will result in death. Initiation of ventilatory care and maintenance of ventilatory care often requires minimal doses of non-depolarising muscle relaxants. The use of depolarising muscle relaxants such as suxamethonium is contraindicated in OP poisoning. The duration of ventilatory care required by patients may differ considerably and it is usual for patients to need ventilatory support for 7-15 days and even up to 21 days. Weaning from ventilatory care is best carried out in stages, with provision of continuous positive airway pressure prior to complete weaning. Continuous and close monitoring of respiratory function (arterial oxygen saturation, partial pressure of oxygen in arterial blood, partial pressure of carbon dioxide in arterial blood) and acid-base status are an absolute necessity. Prophylactic antibiotics are usually not required unless there has been evidence of aspiration of material into the lungs. Close monitoring of fluid and electrolyte balance is mandatory in view of the profuse offensive diarrhoea that most patients develop. Maintenance of nutrition, physiotherapy, prevention of bed sores and other routine measures to minimise discomfort during ventilatory care are necessary. Recovery from the intermediate syndrome is normally complete and without any sequelae. The usefulness of oximes during the IMS remains uncertain. In animal experiments, very early administration of oximes has prevented the occurrence of myopathy. There are reports from developed countries where administration of oximes at recommended doses and within 2 hours of ingestion of OP insecticide did not prevent the onset of the IMS. Controlled randomised clinical studies are necessary to evaluate the efficacy of oximes in combating the IMS. Electrophysiological studies following OP poisoning have revealed three characteristic phenomena: (i) repetitive firing following a single stimulus; (ii) gradual reduction in twitch height or compound muscle action potential followed by an increase with repetitive stimulation (the 'decrement-increment response'); and (iii) continued reduction in twitch height or compound muscle action potential with repetitive simulation ('decrementing response'). Of these, the decrementing response is the most frequent finding during the IMS, whilst repetitive firing is observed during the acute cholinergic syndrome. The distribution of the weakness in human cases of the IMS, in general, parallels the distribution of the myopathy observed in a number of studies in experimental animals. This has led to speculation that myopathy is involved in the causation of the IMS. However, while myopathy and the IMS have a common origin in acetylcholine accumulation, they are not causally related to one another.

Mechanical Ventilation: State of the Art.

PubMed

Pham, Tài; Brochard, Laurent J; Slutsky, Arthur S

2017-09-01

Mechanical ventilation is the most used short-term life support technique worldwide and is applied daily for a diverse spectrum of indications, from scheduled surgical procedures to acute organ failure. This state-of-the-art review provides an update on the basic physiology of respiratory mechanics, the working principles, and the main ventilatory settings, as well as the potential complications of mechanical ventilation. Specific ventilatory approaches in particular situations such as acute respiratory distress syndrome and chronic obstructive pulmonary disease are detailed along with protective ventilation in patients with normal lungs. We also highlight recent data on patient-ventilator dyssynchrony, humidified high-flow oxygen through nasal cannula, extracorporeal life support, and the weaning phase. Finally, we discuss the future of mechanical ventilation, addressing avenues for improvement. Copyright © 2017 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.

Lung Transcriptomics during Protective Ventilatory Support in Sepsis-Induced Acute Lung Injury

PubMed Central

Acosta-Herrera, Marialbert; Lorenzo-Diaz, Fabian; Pino-Yanes, Maria; Corrales, Almudena; Valladares, Francisco; Klassert, Tilman E.; Valladares, Basilio; Slevogt, Hortense; Ma, Shwu-Fan

2015-01-01

Acute lung injury (ALI) is a severe inflammatory process of the lung. The only proven life-saving support is mechanical ventilation (MV) using low tidal volumes (LVT) plus moderate to high levels of positive end-expiratory pressure (PEEP). However, it is currently unknown how they exert the protective effects. To identify the molecular mechanisms modulated by protective MV, this study reports transcriptomic analyses based on microarray and microRNA sequencing in lung tissues from a clinically relevant animal model of sepsis-induced ALI. Sepsis was induced by cecal ligation and puncture (CLP) in male Sprague-Dawley rats. At 24 hours post-CLP, septic animals were randomized to three ventilatory strategies: spontaneous breathing, LVT (6 ml/kg) plus 10 cmH2O PEEP and high tidal volume (HVT, 20 ml/kg) plus 2 cmH2O PEEP. Healthy, non-septic, non-ventilated animals served as controls. After 4 hours of ventilation, lung samples were obtained for histological examination and gene expression analysis using microarray and microRNA sequencing. Validations were assessed using parallel analyses on existing publicly available genome-wide association study findings and transcriptomic human data. The catalogue of deregulated processes differed among experimental groups. The ‘response to microorganisms’ was the most prominent biological process in septic, non-ventilated and in HVT animals. Unexpectedly, the ‘neuron projection morphogenesis’ process was one of the most significantly deregulated in LVT. Further support for the key role of the latter process was obtained by microRNA studies, as four species targeting many of its genes (Mir-27a, Mir-103, Mir-17-5p and Mir-130a) were found deregulated. Additional analyses revealed 'VEGF signaling' as a central underlying response mechanism to all the septic groups (spontaneously breathing or mechanically ventilated). Based on this data, we conclude that a co-deregulation of 'VEGF signaling' along with 'neuron projection morphogenesis', which have been never anticipated in ALI pathogenesis, promotes lung-protective effects of LVT with high levels of PEEP. PMID:26147972

Determinants of ventilation and pulmonary artery pressure during early acclimatization to hypoxia in humans

PubMed Central

Fatemian, Marzieh; Herigstad, Mari; Croft, Quentin P. P.; Formenti, Federico; Cardenas, Rosa; Wheeler, Carly; Smith, Thomas G.; Friedmannova, Maria; Dorrington, Keith L.

2015-01-01

Key points Lung ventilation and pulmonary artery pressure rise progressively in response to 8 h of hypoxia, changes described as ‘acclimatization to hypoxia’. Acclimatization responses differ markedly between humans for unknown reasons.We explored whether the magnitudes of the ventilatory and vascular responses were related, and whether the degree of acclimatization could be predicted by acute measurements of ventilatory and vascular sensitivities.In 80 healthy human volunteers measurements of acclimatization were made before, during, and after a sustained exposure to 8 h of isocapnic hypoxia.No correlation was found between measures of ventilatory and pulmonary vascular acclimatization.The ventilatory chemoreflex sensitivities to acute hypoxia and hypercapnia all increased in proportion to their pre‐acclimatization values following 8 h of hypoxia. The peripheral (rapid) chemoreflex sensitivity to CO2, measured before sustained hypoxia against a background of hyperoxia, was a modest predictor of ventilatory acclimatization to hypoxia. This finding has relevance to predicting human acclimatization to the hypoxia of altitude. Abstract Pulmonary ventilation and pulmonary arterial pressure both rise progressively during the first few hours of human acclimatization to hypoxia. These responses are highly variable between individuals, but the origin of this variability is unknown. Here, we sought to determine whether the variabilities between different measures of response to sustained hypoxia were related, which would suggest a common source of variability. Eighty volunteers individually underwent an 8‐h isocapnic exposure to hypoxia (end‐tidal P O2=55 Torr) in a purpose‐built chamber. Measurements of ventilation and pulmonary artery systolic pressure (PASP) assessed by Doppler echocardiography were made during the exposure. Before and after the exposure, measurements were made of the ventilatory sensitivities to acute isocapnic hypoxia (GpO2) and hyperoxic hypercapnia, the latter divided into peripheral (G pC O2) and central (G cC O2) components. Substantial acclimatization was observed in both ventilation and PASP, the latter being 40% greater in women than men. No correlation was found between the magnitudes of pulmonary ventilatory and pulmonary vascular responses. For GpO2, G pC O2 and G cC O2, but not the sensitivity of PASP to acute hypoxia, the magnitude of the increase during acclimatization was proportional to the pre‐acclimatization value. Additionally, the change in GpO2 during acclimatization to hypoxia correlated well with most other measures of ventilatory acclimatization. Of the initial measurements prior to sustained hypoxia, only G pC O2 predicted the subsequent rise in ventilation and change in GpO2 during acclimatization. We conclude that the magnitudes of the ventilatory and pulmonary vascular responses to sustained hypoxia are predominantly determined by different factors and that the initial G pC O2 is a modest predictor of ventilatory acclimatization. PMID:25907672

Respiratory symptoms and ventilatory performance in workers exposed to grain and grain based food dusts.

PubMed

Deacon, S P; Paddle, G M

1998-05-01

A health surveillance study of male grain food manufacturing workers used a respiratory health questionnaire and spirometry to assess the prevalence of work-related respiratory symptoms and impaired ventilatory performance. The prevalence of cough, breathlessness, wheeze and chest tightness was between 8-13% but was 20% for rhinitis. Rhinitis was the most common symptom with 37% of those reporting rhinitis describing this as work-related. A case-control analysis of workers reporting rhinitis did not identify any specific occupational activities associated with increased risk of rhinitis. Smoking habit and all respiratory symptoms apart from rhinitis had a significant effect upon ventilatory performance. Occupational exposure to raw grains, flour, ingredients and finished food was categorized as high, medium or low in either continuous or intermediate patterns. Multiple regression analysis confirmed the effects of height, age and smoking upon ventilatory performance. However, occupational exposure to grain, flour, food ingredients and cooked food dusts had no effect upon ventilatory performance. It is concluded that smoking habit is the major determinant of respiratory symptoms and impaired ventilatory function. The excess complaints of rhinitis warrant further study but it would appear that the current occupational exposure limits for grain, flour, food ingredients and cooked food dusts are adequate to protect workers against impairment of ventilatory performance.

A review of the lung transplantation programme in Ireland 2005-2007.

PubMed

Bartosik, Waldemar; Egan, Jim J; Soo, Alan; Remund, Kaspar F; Nölke, Lars; McCarthy, James F; Wood, Alfred E

2009-05-01

Lung transplantation is a recognised surgical option for patients with end stage respiratory disease. We present data relating to the initiation of the Irish lung transplant programme in 2005. Seventeen patients: 7 male and 10 female have undergone lung transplantation. The indications for lung transplantation included COPD (n=8), idiopathic pulmonary fibrosis (n=5), bronchiolitis obliterans (n=2), lymphangioleiomyomatosis (n=1), and cystic fibrosis (n=1). Eleven single lungs transplants were completed, while six patients underwent double sequential lung transplantation. The immunosuppression regimen included basiliximab as induction therapy, with steroids, mycophenolate mofetil nd cyclosporine or tacrolimus. The operative mortality was zero. One patient died at 10 months post double lung transplantation secondary to bronchiolitis obliterans. Primary graft dysfunction was observed in two patients who required ventilatory support for 3 and 5 days respectively. Acute cellular rejection was observed in four patients (grade A2 n=3, grade A3 n=2). The cumulative 1-year survival was 94.1%, which compares favourably to an international standard of 78%. The initiation of a lung transplant programme in Ireland has been successfully undertaken and initially provided results comparable to established lung transplant programs.

Spontaneously regulated vs. controlled ventilation of acute lung injury/acute respiratory distress syndrome.

PubMed

Marini, John J

2011-02-01

To present an updated discussion of those aspects of controlled positive pressure breathing and retained spontaneous regulation of breathing that impact the management of patients whose tissue oxygenation is compromised by acute lung injury. The recent introduction of ventilation techniques geared toward integrating natural breathing rhythms into even the earliest phase of acute respiratory distress syndrome support (e.g., airway pressure release, proportional assist ventilation, and neurally adjusted ventilatory assist), has stimulated a burst of new investigations. Optimizing gas exchange, avoiding lung injury, and preserving respiratory muscle strength and endurance are vital therapeutic objectives for managing acute lung injury. Accordingly, comparing the physiology and consequences of breathing patterns that preserve and eliminate breathing effort has been a theme of persisting investigative interest throughout the several decades over which it has been possible to sustain cardiopulmonary life support outside the operating theater.

Tidal volume in acute respiratory distress syndrome: how best to select it.

PubMed

Umbrello, Michele; Marino, Antonella; Chiumello, Davide

2017-07-01

Mechanical ventilation is the type of organ support most widely provided in the intensive care unit. However, this form of support does not constitute a cure for acute respiratory distress syndrome (ARDS), as it mainly works by buying time for the lungs to heal while contributing to the maintenance of vital gas exchange. Moreover, it can further damage the lung, leading to the development of a particular form of lung injury named ventilator-induced lung injury (VILI). Experimental evidence accumulated over the last 30 years highlighted the factors associated with an injurious form of mechanical ventilation. The present paper illustrates the physiological effects of delivering a tidal volume to the lungs of patients with ARDS, and suggests an approach to tidal volume selection. The relationship between tidal volume and the development of VILI, the so called volotrauma, will be reviewed. The still actual suggestion of a lung-protective ventilatory strategy based on the use of low tidal volumes scaled to the predicted body weight (PBW) will be presented, together with newer strategies such as the use of airway driving pressure as a surrogate for the amount of ventilatable lung tissue or the concept of strain, i.e., the ratio between the tidal volume delivered relative to the resting condition, that is the functional residual capacity (FRC). An ultra-low tidal volume strategy with the use of extracorporeal carbon dioxide removal (ECCO 2 R) will be presented and discussed. Eventually, the role of other ventilator-related parameters in the generation of VILI will be considered (namely, plateau pressure, airway driving pressure, respiratory rate (RR), inspiratory flow), and the promising unifying framework of mechanical power will be presented.

Tidal volume in acute respiratory distress syndrome: how best to select it

PubMed Central

Umbrello, Michele; Marino, Antonella

2017-01-01

Mechanical ventilation is the type of organ support most widely provided in the intensive care unit. However, this form of support does not constitute a cure for acute respiratory distress syndrome (ARDS), as it mainly works by buying time for the lungs to heal while contributing to the maintenance of vital gas exchange. Moreover, it can further damage the lung, leading to the development of a particular form of lung injury named ventilator-induced lung injury (VILI). Experimental evidence accumulated over the last 30 years highlighted the factors associated with an injurious form of mechanical ventilation. The present paper illustrates the physiological effects of delivering a tidal volume to the lungs of patients with ARDS, and suggests an approach to tidal volume selection. The relationship between tidal volume and the development of VILI, the so called volotrauma, will be reviewed. The still actual suggestion of a lung-protective ventilatory strategy based on the use of low tidal volumes scaled to the predicted body weight (PBW) will be presented, together with newer strategies such as the use of airway driving pressure as a surrogate for the amount of ventilatable lung tissue or the concept of strain, i.e., the ratio between the tidal volume delivered relative to the resting condition, that is the functional residual capacity (FRC). An ultra-low tidal volume strategy with the use of extracorporeal carbon dioxide removal (ECCO2R) will be presented and discussed. Eventually, the role of other ventilator-related parameters in the generation of VILI will be considered (namely, plateau pressure, airway driving pressure, respiratory rate (RR), inspiratory flow), and the promising unifying framework of mechanical power will be presented. PMID:28828362

Mechanical ventilation strategies.

PubMed

Keszler, Martin

2017-08-01

Although only a small proportion of full term and late preterm infants require invasive respiratory support, they are not immune from ventilator-associated lung injury. The process of lung damage from mechanical ventilation is multifactorial and cannot be linked to any single variable. Atelectrauma and volutrauma have been identified as the most important and potentially preventable elements of lung injury. Respiratory support strategies for full term and late preterm infants have not been as thoroughly studied as those for preterm infants; consequently, a strong evidence base on which to make recommendations is lacking. The choice of modalities of support and ventilation strategies should be guided by the specific underlying pathophysiologic considerations and the ventilatory approach must be individualized for each patient based on the predominant pathophysiology at the time. Copyright © 2017 Elsevier Ltd. All rights reserved.

Idiopathic pulmonary fibrosis misdiagnosed as sputum-negative pulmonary tuberculosis.

PubMed

Isah, Muhammad Danasabe; Abbas, Aminu; Abba, Abdullahi A; Umar, Mohammed

2016-01-01

Idiopathic pulmonary fibrosis (IPF), also known as cryptogenic fibrosing alveolitis, is one of a spectrum of idiopathic interstitial pneumonia. IPF is an increasingly common condition which poses many diagnostic and therapeutic challenges leading to misdiagnosis and mismanagement. We presented a 55-year-old male textile trader who was initially managed as sputum-negative pulmonary tuberculosis before histology report. He presented to our clinic with Breathlessness and cough of 3 years and 2.5 years, respectively. He had commenced anti-tuberculosis two months before presentation without significant relief. General Physical examination and vital signs were essentially normal. SPO2 was 96% on room air. Chest Examination revealed end-inspiratory bi-basal velcro-like crackles. Other systemic examinations were normal. Radiological examination by way of chest X- ray and chest CT showed features suggestive of IPF. The patient also had open Lung biopsy for histology and spirometry which demonstrated restrictive ventilatory function pattern. A diagnosis of Interstitial lung disease probably Idiopathic Pulmonary Fibrosis was entertained. He was commenced on Tab prednisolone, Tab Rabeprazole, with minimal improvement. IPF have often been misdiagnosed and treated as pulmonary tuberculosis with unfavorable outcome.

Long term effects of prenatal and postnatal airborne PAH exposures on ventilatory lung function of non-asthmatic preadolescent children. Prospective birth cohort study in Krakow.

PubMed

Jedrychowski, Wieslaw A; Perera, Frederica P; Maugeri, Umberto; Majewska, Renata; Mroz, Elzbieta; Flak, Elzbieta; Camann, David; Sowa, Agata; Jacek, Ryszard

2015-01-01

The main goal of the study was to test the hypothesis that prenatal and postnatal exposures to polycyclic aromatic hydrocarbons (PAH) are associated with depressed lung function in non-asthmatic children. The study sample comprises 195 non-asthmatic children of non-smoking mothers, among whom the prenatal PAH exposure was assessed by personal air monitoring in pregnancy. At the age of 3, residential air monitoring was carried out to evaluate the residential PAH exposure indoors and outdoors. At the age of 5 to 8, children were given allergic skin tests for indoor allergens; and between 5 and 9 years lung function testing (FVC, FEV05, FEV1 and FEF25-75) was performed. The effects of prenatal PAH exposure on lung function tests repeated over the follow-up were adjusted in the General Estimated Equation (GEE) model for the relevant covariates. No association between FVC with prenatal PAH exposure was found; however for the FEV1 deficit associated with higher prenatal PAH exposure (above 37 ng/m(3)) amounted to 53 mL (p=0.050) and the deficit of FEF25-75 reached 164 mL (p=0.013). The corresponding deficits related to postnatal residential indoor PAH level (above 42 ng/m(3)) were 59 mL of FEV1 (p=0.028) and 140 mL of FEF25-75 (p=0.031). At the higher residential outdoor PAH level (above 90 ng/m(3)) slightly greater deficit of FEV1 (71 mL, p=0.009) was observed. The results of the study suggest that transplacental exposure to PAH compromises the normal developmental process of respiratory airways and that this effect is compounded by postnatal PAH exposure. Copyright © 2014 Elsevier B.V. All rights reserved.

Health risk assessment due to biomass smoke exposure in Indian indoor environment: An empirical approach using lung deposition model.

PubMed

Tigala, Snehlata; Sharma, Anu Rani; Sachdeva, Kamna

2018-06-04

The paper subsumes a framework that assesses health risk due to exposure to different fuel combustion through articulation of modern microscopic techniques, empirical equations, lung diagnostic tools and a pre-existing model that has been extrapolated to futuristic aspects (within controlled conditions). The framework was tested on 132 household cooks belonging to different age groups and using different types of fuel. The inhalable fraction released during fuel combustion varied in morphological characteristics and deposition site. Micrographs obtained using Scanning Electron Microscope (SEM) analysis of (biomass smoke) soot indicates aggregate formation attributing to a higher level of health risk. Further, abnormal ventilatory function along with higher risk (RR > 1) was more evident within biomass fuel users. The condition further exacerbates while using dung cakes due to high levels of emissions (294.3 particles/liter) that deposit in the upper respiratory tract (0.0899). Further, the population attributable risk percent (79%) calculated on the basis of cooking behavior suggests a 'rural culture' health determinant as clean fuel usage is not practiced as an outcome of low literacy and poor income in the region. These preliminary findings highlight the drudgery of impuissant women who are exposed to high particulate emissions on a regular basis which results in reduced lung function. Nevertheless, further cogitation is required to eliminate the limitations in this study and explore further linkages between exposure and vulnerable group to generate meaningful policy recommendations. Copyright © 2018 Elsevier B.V. All rights reserved.

Respiratory effects of work in retail food stores. III. Pulmonary function findings.

PubMed

Wegman, D H; Eisen, E A; Smith, T J; Greaves, I A; Fine, L J

1987-06-01

Findings are reported from a prospective morbidity study which examined the effects on pulmonary function associated with the particulate and gaseous air contaminants to which retail food store workers are exposed. A total of 685 supermarket employees (including meat wrappers, meat cutters and store clerks) performed standard ventilatory function tests [forced expiratory volume in 1 s (FEV1.0) and forced vital capacity (FVC)] during a base-line survey. Those available four years later (305) were resurveyed in a similar manner. A suggestive chronic effect on pulmonary function was shown in those with high cumulative exposures and allergic history. Among those workers who had continuous exposure to air contaminants in settings with "hot-wire" plastic wrap film cutters the annual rates of change in FEV1.0 and FVC were twice as great as the changes found among comparable workers who were not exposed to fumes from wrapping film. Those who switched from the "hot-wire" to the "cool-rod" cutters during the course of the follow-up had intermediate rates of change in lung function.

Dynamic Determination of Oxygenation and Lung Compliance in Murine Pneumonectomy

PubMed Central

Gibney, Barry; Lee, Grace S.; Houdek, Jan; Lin, Miao; Miele, Lino; Chamoto, Kenji; Konerding, Moritz A.; Tsuda, Akira; Mentzer, Steven J.

2012-01-01

Thoracic surgical procedures in mice have been applied to a wide range of investigations, but little is known about the murine physiologic response to pulmonary surgery. Using continuous arterial oximetry monitoring and the FlexiVent murine ventilator, we investigated the effect of anesthesia and pneumonectomy on mouse oxygen saturation and lung mechanics. Sedation resulted in a dose-dependent decline of oxygen saturation that ranged from 55–82%. Oxygen saturation was restored by mechanical ventilation with increased rate and tidal volumes. In the mouse strain studied, optimal ventilatory rates were a rate of 200/minute and a tidal volume of 10ml/kg. Sustained inflation pressures, referred to as a "recruitment maneuver," improved lung volumes, lung compliance and arterial oxygenation. In contrast, positive end expiratory pressure (PEEP) had a detrimental effect on oxygenation; an effect that was ameliorated after pneumonectomy. Our results confirm that lung volumes in the mouse are dynamically determined and suggest a threshold level of mechanical ventilation to maintain perioperative oxygen saturation. PMID:21574875

Ventilatory effects of substance P-saporin lesions in the nucleus tractus solitarii of chronically hypoxic rats

PubMed Central

Fu, Zhenxing; Powell, Frank L.

2011-01-01

During ventilatory acclimatization to hypoxia (VAH), time-dependent increases in ventilation lower Pco2 levels, and this persists on return to normoxia. We hypothesized that plasticity in the caudal nucleus tractus solitarii (NTS) contributes to VAH, as the NTS receives the first synapse from the carotid body chemoreceptor afferents and also contains CO2-sensitive neurons. We lesioned cells in the caudal NTS containing the neurokinin-1 receptor by microinjecting the neurotoxin saporin conjugated to substance P and measured ventilatory responses in awake, unrestrained rats 18 days later. Lesions did not affect hypoxic or hypercapnic ventilatory responses in normoxic control rats, in contrast to published reports for similar lesions in other central chemosensitive areas. Also, lesions did not affect the hypercapnic ventilatory response in chronically hypoxic rats (inspired Po2 = 90 Torr for 7 days). These results suggest functional differences between central chemoreceptor sites. However, lesions significantly increased ventilation in normoxia or acute hypoxia in chronically hypoxic rats. Hence, chronic hypoxia increases an inhibitory effect of neurokinin-1 receptor neurons in the NTS on ventilatory drive, indicating that these neurons contribute to plasticity during chronic hypoxia, although such plasticity does not explain VAH. PMID:21593425

Acute lung injury following refrigeration coil deicing.

PubMed

McKeown, Nathanael J; Burton, Brent T

2012-03-01

We report a case of a worker who developed ALI requiring mechanical ventilatory support after attempting to melt ice condensate by applying the flame of an oxy-acetylene torch to refrigeration coils charged with a halocarbon refrigerant in a closed environment. A discussion of possible etiologies are discussed, including phosgene, carbonyl fluoride, and nitrogen oxides. Primary prevention with adequate respiratory protection is recommended whenever deicing is performed in a closed space environment.

Effect of Same-day Sequential Exposure to Nitrogen Dioxide and Ozone on Cardiac and Ventilatory Function in Mice

EPA Science Inventory

This study examines the cardiac and ventilatory effects of sequential exposure to nitrogen dioxide and then ozone. The data show that mice exposed to both gases have increased arrhythmia and breathing changes not observed in the other groups. Although the mechanisms underlying ai...

[Analogies between heart and respiratory muscle failure. Importance to clinical practice].

PubMed

Köhler, D

2009-01-01

Heart failure is an established diagnosis. Respiratory muscle or ventilatory pump failure, however, is less well known. The latter becomes obvious through hypercapnia, caused by hypoventilation. The respiratory centre tunes into hypercapnea in order to prevent the danger of respiratory muscle overload (hypercapnic ventilatory failure). Hypoventilation will consecutively cause hypoxemia but this will not be responsible for performance limitation. One therefore has to distinguish primary hypoxemia evolving from diseases in the lung parenchyma. Here hypoxemia is the key feature and compensatory hyperventilation usually decreases PaCO2 levels. The cardiac as well as the respiratory pump adapt to an inevitable burden caused by chronic disease. In either case organ muscle mass will increase. If the burden exceeds the range of possible physiological adaptation, compensatory mechanisms will set in that are similar in both instances. During periods of overload either muscle system is mainly fueled by muscular glycogen. In the recovery phase (e. g. during sleep) stores are replenished, which can be recognized by down-regulation of the blood pressure in case of the cardiac pumb or by augmentation of hypercapnia through hypoventilation in case of the respiratory pump. The main function of cardiac and respiratory pump is maintenance of oxygen transport. The human body has developed certain compensatory mechanisms to adapt to insufficient oxygen supply especially during periods of overload. These mechanisms include shift of the oxygen binding curve, expression of respiratory chain isoenzymes capable of producing ATP at lower partial pressures of oxygen and the development of polyglobulia. Medically or pharmacologically the cardiac pump can be unloaded with beta blockers, the respiratory pump by application of inspired oxygen. Newer forms of therapy augment the process of recovery. The heart can be supported through bypass surgery or intravascular pump systems, while respiratory muscles may be supported through elective ventilatory support (mainly non-invasive) in the patient's home. The latter treatment in particular will increase patient endurance and quality of life and decrease mortality. Heart and respiratory pump failure share many common features. Since both take care of oxygen supply to the body, their function and compensatory mechanisms are closely related and linked.

Pulmonary rehabilitation improves cardiovascular response to exercise in COPD.

PubMed

Ramponi, Sara; Tzani, Panagiota; Aiello, Marina; Marangio, Emilio; Clini, Enrico; Chetta, Alfredo

2013-01-01

Pulmonary rehabilitation (PR) has emerged as a recommended standard of care in symptomatic COPD. We now studied whether PR may affect cardiovascular response to exercise in these patients. Twenty-seven patients (9 females aged 69 ± 8 years) with moderate-to-severe airflow obstruction admitted to a 9-week PR course performed a pre-to-post evaluation of lung function test and symptom-limited cardiopulmonary exercise test (CPET). Oxygen uptake (VO2), tidal volume (V(T)), dyspnea and leg fatigue scores were measured during CPET. Cardiovas-cular response was assessed by means of oxygen pulse (O2Pulse), the oxygen uptake efficiency slope and heart rate recovery at the 1st min. A significant increase in peak VO2 and in all cardiovascular parameters (p < 0.05) was found following PR when compared to baseline. Leg fatigue (p < 0.05), but not dyspnea, was significantly reduced after PR. When assessed at metabolic and ventilatory iso levels [% VCO2max and % minute ventilation (VEmax)], O2Pulse and V(T) were significantly higher (p < 0.05) at submaximal exercise (75 and 50% of VCO2max and VEmax) after PR when compared to baseline. V(T) percent changes at 75% VCO2max and 75% VEmax after PR significantly correlated with corresponding changes in O2Pulse (p < 0.01). In COPD patients, a PR training program improved the cardiovascular response during exercise at submaximal exercise independent of the external workload. This change was associated with an enhanced ventilatory function during exercise. Copyright © 2013 S. Karger AG, Basel.

Assessment of two novel ventilatory surrogates for use in the delivery of gated/tracked radiotherapy for non-small cell lung cancer.

PubMed

Hughes, Simon; McClelland, James; Tarte, Segolene; Lawrence, David; Ahmad, Shahreen; Hawkes, David; Landau, David

2009-06-01

In selected patients with NSCLC the therapeutic index of radical radiotherapy can be improved with gating/tracking technology. Both techniques require real-time information on target location. This is often derived from a surrogate ventilatory signal. We assessed the correlation of two novel surrogate ventilatory signals with a spirometer-derived signal. The novel signals were obtained using the VisionRT stereoscopic camera system. The VisionRT-Tracked-Point (VRT-TP) signal was derived from tracking a point located midway between the umbilicus and xiphisternum. The VisionRT-Surface-Derived-Volume (VRT-SDV) signal was derived from 3D body surface imaging of the torso. Both have potential advantages over the current surrogate signals. Eleven subjects with NSCLC were recruited. Each was positioned as for radiotherapy treatment, and then instructed to breathe in five different modes: normal, abdominal, thoracic, deep and shallow breathing. Synchronous ventilatory signals were recorded for later analysis. The signals were analysed for correlation across all modes of breathing, and phase shifts. The VRT-SDV was also assessed for its ability to determine the mode of breathing. Both novel respiratory signals showed good correlation (r>0.80) with spirometry in 9 of 11 subjects. For all subjects the correlation with spirometry was better for the VRT-SDV signal than for the VRT-TP signal. Only one subject displayed a phase shift between the VisionRT-derived signals and spirometry. The VRT-SDV signal could also differentiate between different modes of breathing. Unlike the spirometer-derived signal, neither VisionRT-derived signal was subject to drift. Both the VRT-TP and VRT-SDV signals have potential applications in ventilatory-gated and tracked radiotherapy. They can also be used as a signal for sorting 4DCT images, and to drive 4DCT single- and multiple-parameter motion models.

In patients with a tumour invading the phrenic nerve does prophylactic diaphragm plication improve postoperative lung function?

PubMed

Beattie, Gwyn W; Dunn, William G; Asif, Mohammed

2016-09-01

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was 'In patients with tumours involving the phrenic nerve, does prophylactic diaphragm plication improve lung function following tumour resection?' Using the reported search, 258 papers were found of which 6 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Three case reports and one case series represent 37 patients in the literature along with two relevant animal studies. Patients treated with prophylactic plication at the time of injury or sacrifice of the phrenic nerve had reduced radiological evidence of diaphragm paralysis, lower reported shortness of breath and reduced requirement for ventilatory support. In patients with prophylactic diaphragm plication and a concurrent pulmonary resection, the predicted postoperative lung function correlated closely with the postoperative measured FEV1, FVC and gas transfer. The postoperative measured FEV1 was reported as 86-98%, the FVC 82-89% and gas transfer 97% of the predicted values. Two animal models investigate the mechanics of respiration, spirometry and gas exchange following diaphragmatic plication. A randomized control study in four dogs measured a 50% reduction in tidal volume and respiratory rate, a 40% decrease in arterial PO2 and a 43% increase in arterial CO2 when the phrenic nerve was crushed in animals with a pneumonectomy but without prophylactic diaphragm plication. A further randomized control animal study with 28 dogs found that plicating the diaphragm after unilateral phrenic nerve transection resulted in a significant increase in tidal volume and lung compliance and a significant decrease in respiratory frequency and the work of breathing. Prophylactic diaphragm plication may preserve lung function, reduce the risk of ventilator dependence and improve the mechanics of breathing in patients with phrenic nerve transection. If transection of the phrenic nerve occurs, and it is recognized intraoperatively, prophylactic diaphragm plication should be considered. © The Author 2016. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

How to optimize the lung donor.

PubMed

Sales, Gabriele; Costamagna, Andrea; Fanelli, Vito; Boffini, Massimo; Pugliese, Francesco; Mascia, Luciana; Brazzi, Luca

2018-02-01

Over the last two decades, lung transplantation emerged as the standard of care for patients with advanced and terminal lung disease. Despite the increment in lung transplantation rates, in 2016 the overall mortality while on waiting list in Italy reached 10%, whereas only 39% of the wait-list patients were successfully transplanted. A number of approaches, including protective ventilatory strategy, accurate management of fluid balance, and administration of a hormonal resuscitation therapy, have been reported to improve lung donor performance before organ retrieval. These approaches, in conjunction with the use of ex-vivo lung perfusion technique contributed to expand the lung donor pool, without affecting the harvest of other organs and the outcomes of lung recipients. However, the efficacy of issues related to the ex-vivo lung perfusion technique, such as the optimal ventilation strategy, the ischemia-reperfusion induced lung injury management, the prophylaxis of germs transmission from donor to recipient and the application of targeted pharmacologic therapies to treat specific donor lung injuries are still to be explored. The main objective of the present review is to summarize the "state-of-art" strategies to optimize the donor lungs and to present the actual role of ex-vivo lung perfusion in the process of lung transplant. Moreover, different approaches about the technique reported in literature and several issues that are under investigation to treat specific donor lung injury will be discussed.

Strategic plan for pediatric respiratory diseases research: an NHLBI working group report.

PubMed

Castro, Mario; Ramirez, Maria I; Gern, James E; Cutting, Garry; Redding, Greg; Hagood, James S; Whitsett, Jeffrey; Abman, Steve; Raj, J Usha; Barst, Robyn; Kato, Gregory J; Gozal, David; Haddad, Gabriel G; Prabhakar, Nanduri R; Gauda, Estelle; Martinez, Fernando D; Tepper, Robert; Wood, Robert E; Accurso, Frank; Teague, W Gerald; Venegas, Jose; Cole, F Sessions; Wright, Rosalind J

2009-01-15

The Division of Lung Diseases of the National Heart, Lung, and Blood Institute (NHLBI) recently held a workshop to identify gaps in our understanding and treatment of childhood lung diseases and to define strategies to enhance translational research in this field. Leading experts with diverse experience in both laboratory and patient-oriented research reviewed selected areas of pediatric lung diseases, including perinatal programming and epigenetic influences; mechanisms of lung injury, repair, and regeneration; pulmonary vascular disease; sleep and control of breathing; and the application of novel translational methods to enhance personalized medicine. This report summarizes the proceedings of this workshop and provides recommendations for emphasis on targeted areas for future investigation. The priority areas identified for research in pediatric pulmonary diseases included: (1) epigenetic and environmental influences on lung development that program pediatric lung diseases; (2) injury, regeneration, and repair in the developing lung; (3) pulmonary vascular disease in children; (4) development and adaptation of ventilatory responses to postnatal life; (5) nonatopic wheezing: aberrant large airway development or injury?; (6) strategies to improve assessment, diagnosis, and treatment of pediatric respiratory diseases; and (7) predictive and personalized medicine for children.

Effects of low temperature on breathing pattern and ventilatory responses during hibernation in the golden-mantled ground squirrel.

PubMed

Webb, Cheryl L; Milsom, William K

2017-07-01

During entrance into hibernation in golden-mantled ground squirrels (Callospermophilus lateralis), ventilation decreases as metabolic rate and body temperature fall. Two patterns of respiration occur during deep hibernation. At 7 °C body temperature (T b ), a breathing pattern characterized by episodes of multiple breaths (20.6 ± 1.9 breaths/episode) separated by long apneas or nonventilatory periods (T nvp ) (mean = 11.1 ± 1.2 min) occurs, while at 4 °C T b , a pattern in which breaths are evenly distributed and separated by a relatively short T nvp (0.5 ± 0.05 min) occurs. Squirrels exhibiting each pattern have similar metabolic rates and levels of total ventilation (0.2 and 0.23 ml O 2 /hr/kg and 0.11 and 0.16 ml air/min/kg, respectively). Squirrels at 7 °C T b exhibit a significant hypoxic ventilatory response, while squirrels at 4 °C T b do not respond to hypoxia at any level of O 2 tested. Squirrels at both temperatures exhibit a significant hypercapnic ventilatory response, but the response is significantly reduced in the 4 °C T b squirrels. Carotid body denervation has little effect on the breathing patterns or on the hypercapnic ventilatory responses. It does reduce the magnitude and threshold for the hypoxic ventilatory response. Taken together the data suggest that (1) the fundamental rhythm generator remains functional at low temperatures; (2) the hypercapnic ventilatory response arises from central chemoreceptors that remain functional at very low temperatures; (3) the hypoxic ventilatory response arises from both carotid body and aortic chemoreceptors that are silenced at lower temperatures; and (4) there is a strong correlation between breathing pattern and chemosensitivity.

Relationship between pulmonary function and indoor air pollution from coal combustion among adult residents in an inner-city area of southwest China

PubMed Central

Jie, Y.; Houjin, H.; Xun, M.; Kebin, L.; Xuesong, Y.; Jie, X.

2014-01-01

Few studies evaluate the amount of particulate matter less than 2.5 mm in diameter (PM2.5) in relation to a change in lung function among adults in a population. The aim of this study was to assess the association of coal as a domestic energy source to pulmonary function in an adult population in inner-city areas of Zunyi city in China where coal use is common. In a cross-sectional study of 104 households, pulmonary function measurements were assessed and compared in 110 coal users and 121 non-coal users (≥18 years old) who were all nonsmokers. Several sociodemographic factors were assessed by questionnaire, and ventilatory function measurements including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), the FEV1/FVC ratio, and peak expiratory flow rate (PEFR) were compared between the 2 groups. The amount of PM2.5 was also measured in all residences. There was a significant increase in the relative concentration of PM2.5 in the indoor kitchens and living rooms of the coal-exposed group compared to the non-coal-exposed group. In multivariate analysis, current exposure to coal smoke was associated with a 31.7% decrease in FVC, a 42.0% decrease in FEV1, a 7.46% decrease in the FEV1/FVC ratio, and a 23.1% decrease in PEFR in adult residents. The slope of lung function decrease for Chinese adults is approximately a 2-L decrease in FVC, a 3-L decrease in FEV1, and an 8 L/s decrease in PEFR per count per minute of PM2.5 exposure. These results demonstrate the harmful effects of indoor air pollution from coal smoke on the lung function of adult residents and emphasize the need for public health efforts to decrease exposure to coal smoke. PMID:25296361

The connection between chronic obstructive pulmonary disease symptoms and hyperinflation and its impact on exercise and function.

PubMed

Cooper, Christopher B

2006-10-01

Forced expiratory volume in 1 second (FEV1) has served as an important diagnostic measurement of chronic obstructive pulmonary disease (COPD) but has not been found to correlate with patient-centered outcomes such as exercise tolerance, dyspnea, or health-related quality of life. It has not helped us understand why some patients with severe FEV1 impairment have better exercise tolerance compared with others with similar FEV1 values. Hyperinflation, or air trapping caused by expiratory flow limitation, causes operational lung volumes to increase and even approach the total lung capacity (TLC) during exercise. Some study findings suggest that a dyspnea limit is reached when the end-inspiratory lung volume encroaches within approximately 500 mL of TLC. The resulting limitation in daily physical activity establishes a cycle of decline that includes physical deconditioning (elevated blood lactic acid levels at lower levels of exercise) and worsening dyspnea. Hyperinflation is reduced by long-acting bronchodilators that reduce airways resistance. The deflation of the lungs, in turn, results in an increased inspiratory capacity. For example, the once-daily anticholinergic bronchodilator tiotropium increases inspiratory capacity, 6-minute walk distance, and cycle exercise endurance time, and it decreases isotime fatigue or dyspnea. Pulmonary rehabilitation and oxygen therapy both reduce ventilatory requirements and improve breathing efficiency, thereby reducing hyperinflation and improving exertional dyspnea. Thus, hyperinflation is directly associated with patient-centered outcomes such as dyspnea and exercise limitation. Furthermore, therapeutic interventions--including pharmacotherapy and lung volume--reduction surgery--that reduce hyperinflation improve these outcomes.

Extra corporeal membrane oxygenation to facilitate lung protective ventilation and prevent ventilator-induced lung injury in severe Pneumocystis pneumonia with pneumomediastinum: a case report and short literature review.

PubMed

Ali, Husain Shabbir; Hassan, Ibrahim Fawzy; George, Saibu

2016-04-14

Pulmonary infections caused by Pneumocystis jirovecii in immunocompromised host can be associated with cysts, pneumatoceles and air leaks that can progress to pneumomediastinum and pneumothoraxes. In such cases, it can be challenging to maintain adequate gas exchange by conventional mechanical ventilation and at the same time prevent further ventilator-induced lung injury. We report a young HIV positive male with poorly compliant lungs and pneumomediastinum secondary to severe Pneumocystis infection, rescued with veno-venous extra corporeal membrane oxygenation (V-V ECMO). A 26 year old male with no significant past medical history was admitted with fever, cough and shortness of breath. He initially required non-invasive ventilation for respiratory failure. However, his respiratory function progressively deteriorated due to increasing pulmonary infiltrates and development of pneumomediastinum, eventually requiring endotracheal intubation and invasive ventilation. Despite attempts at optimizing gas exchange by ventilatory maneuvers, patients' pulmonary parameters worsened necessitating rescue ECMO therapy. The introduction of V-V ECMO facilitated the use of ultra-protective lung ventilation and prevented progression of pneumomediastinum, maintaining optimal gas exchange. It allowed time for the antibiotics to show effect and pulmonary parenchyma to heal. Further diagnostic workup revealed Pneumocystis jirovecii as the causative organism for pneumonia and serology confirmed Human Immunodeficiency Virus infection. Patient was successfully treated with appropriate antimicrobials and de-cannulated after six days of ECMO support. ECMO was an effective salvage therapy in HIV positive patient with an otherwise fatal respiratory failure due to Pneumocystis pneumonia and air leak syndrome.

Sonotubometry, a useful tool for the evaluation of the Eustachian tube ventilatory function

PubMed Central

Borangiu, A; Popescu, CR; Purcarea, VL

2014-01-01

From the three Eustachian tube (ET) functions: middle ear protection, secretion clearance and middle ear ventilation, the ventilatory function is unanimously considered the most important one, because proper hearing is established only when tympanic membrane compliance is normal. This requires equilibrium between the middle ear and ambient gas pressure, which makes the normal functioning of active ET opening of critical importance. There are several methods and tests that can assess such a complex and variable mechanism. Sonotubometry is one such method; despite the fact that it has been continuously improved in the last 20 years, it is not yet systematically used to evaluate the ET ventilatory function, because its measurement pattern, context mapping (patient, clinic data, medication, treatment), validation, reproducibility and value for clinic practice, have not yet been fully consolidated and integrated in a knowledge-based, service-oriented system, that can provide decision support or even diagnostic. The paper reviews the role of tubal sonometry as a non-invasive, physiologic and easy to use method in assessing the ventilatory function and investigates the validity and reproducibility of a measuring pattern and test in a group of children. The paper describes the test pattern used, and the computer-based platform based on: (1) Digital Signal Processing (DSP) for sound acquisition and low-level processing; (2) Artificial Intelligence techniques to extract significant sound features from sonotubograms and learn a manifold context database. Results are reported from test series carried out in healthy children; a similar study between tests is included in the final Discussions section. PMID:25713631

Estrogen attenuates the cardiovascular and ventilatory responses to central command in cats.

PubMed

Hayes, Shawn G; Moya Del Pino, Nicolas B; Kaufman, Marc P

2002-04-01

Static exercise is well known to increase heart rate, arterial blood pressure, and ventilation. These increases appear to be less in women than in men, a difference that has been attributed to an effect of estrogen on neuronal function. In decerebrate male cats, we examined the effect of estrogen (17beta-estradiol; 0.001, 0.01, 0.1, and 1.0 microg/kg iv) on the cardiovascular and ventilatory responses to central command and the exercise pressor reflex, the two neural mechanisms responsible for evoking the autonomic and ventilatory responses to exercise. We found that 17beta-estradiol, in each of the three doses tested, attenuated the pressor, cardioaccelerator, and phrenic nerve responses to electrical stimulation of the mesencephalic locomotor region (i.e., central command). In contrast, none of the doses of 17beta-estradiol had any effect on the pressor, cardioaccelerator, and ventilatory responses to static contraction or stretch of the triceps surae muscles. We conclude that, in decerebrate male cats, estrogen injected intravenously attenuates cardiovascular and ventilatory responses to central command but has no effect on responses to the exercise pressor reflex.

[The repercussions of pulmonary congestion on ventilatory volumes, capacities and flows].

PubMed

Carmo, M M; Ferreira, T; Lousada, N; Bárbara, C; Neves, P R; Correia, J M; Rendas, A B

1994-10-01

To evaluate the effects of pulmonary congestion on pulmonary function. Prospective study performed in patients with left ventricular failure or mitral stenosis. Forty-eight hospitalized patients were included suffering from pulmonary congestion either from left ventricular failure or mitral stenosis. While in hospital all patients were submitted to right heart catheterization by the Swan-Ganz method and also to an echocardiographic examination. Within 48 hours after the patients were submitted to the following lung function studies: lung volumes and capacities by the multi-breath helium dilution method and airway flows by pneumotachography. Respiratory symptoms were evaluated by the Medical Research Council Questionnaire and the functional class classified according to the NYHA. Correlations were made between the functional and clinical data. Regarding the cardiac evaluation patients presented with a mean pulmonary wedge pressure of 19.9 +/- 8.6 mmHg, a cardiac index of 2.5 +/- 0.8 l/min/m2, an end diastolic dimension of the left ventricle of 65.9 +/- 10.1 mm, and end systolic dimension of 51.2 +/- 12.2 mm, with a shortening fraction of 21.8 +/- 9.5%. The pulmonary evaluation showed a restrictive syndrome with a reduction in the mean values of the following parameters: total pulmonary capacity 71 +/- 14.4% of the predicted value (pv), forced vital capacity (FVC) 69.8 +/- 20.5% pv, and forced expiratory volume (FEV1) of 64 +/- 21.8% vp. The index FEV1/FVC was within the normal value of 72.7 +/- 9.7%. These lung function results did not correlate significantly with either the clinical, the hemodynamic or echocardiographic findings. In these group of patients pulmonary congestion led to the development of a restrictive syndrome which failed to correlate in severity with the duration of the disease, the pulmonary wedge pressure and the left ventricular function.

STUDIES ON THE SYNDROME OF FAT EMBOLIZATION.

PubMed

SPROULE, B J; BRADY, J L; GILBERT, J A

1964-05-30

Three patients, all of whom were well-muscled young adult males who had suffered fractures of long bones, were studied by means of measurement of ventilatory function and arterial blood gases. They had degrees of mental change varying from mild confusion to stupor. Anemia, hypocalcemia, skin petechiae and radiologic pulmonary infiltrates were demonstrated in all three.In the absence of any clinical cyanosis, profound arterial O(2) desaturation was demonstrated in all. Physiologic studies indicated that the desaturation was the result of a diffusion defect early in the course of the syndrome and later from venous admixture. The lungs were stiff and the work of breathing was increased. The anemia appeared to be hemolytic in type.It is suggested that anemia, hypocalcemia and arterial O(2) desaturation may contribute significantly to the cerebral symptomatology associated with the syndrome of fat embolization.

Ventilatory abnormalities in patients with cystic fibrosis undergoing the submaximal treadmill exercise test.

PubMed

Parazzi, Paloma Lopes Francisco; Marson, Fernando Augusto de Lima; Ribeiro, Maria Angela Gonçalves de Oliveira; de Almeida, Celize Cruz Bresciani; Martins, Luiz Cláudio; Paschoal, Ilma Aparecida; Toro, Adyleia Aparecida Dalbo Contrera; Schivinski, Camila Isabel Santos; Ribeiro, Jose Dirceu

2015-05-19

Exercise has been studied as a prognostic marker for patients with cystic fibrosis (CF), as well as a tool for improving their quality of life and analyzing lung disease. In this context, the aim of the present study was to evaluate and compare variables of lung functioning. Our data included: (i) volumetric capnography (VCAP) parameters: expiratory minute volume (VE), volume of exhaled carbon dioxide (VCO2), VE/VCO2, ratio of dead space to tidal volume (VD/VT), and end-tidal carbon dioxide (PetCO2); (ii) spirometry parameters: forced vital capacity (FVC), percent forced expiratory volume in the first second of the FVC (FEV1%), and FEV1/FVC%; and (iii) cardiorespiratory parameters: heart rate (HR), respiratory rate, oxygen saturation (SpO2), and Borg scale rating at rest and during exercise. The subjects comprised children, adolescents, and young adults aged 6-25 years with CF (CF group [CFG]) and without CF (control group [CG]). This was a clinical, prospective, controlled study involving 128 male and female patients (64 with CF) of a university hospital. All patients underwent treadmill exercise tests and provided informed consent after study approval by the institutional ethics committee. Linear regression, Kruskal-Wallis test, and Mann-Whitney test were performed to compare the CFG and CG. The α value was set at 0.05. Patients in the CFG showed significantly different VCAP values and spirometry variables throughout the exercise test. Before, during, and after exercise, several variables were different between the two groups; statistically significant differences were seen in the spirometry parameters, SpO2, HR, VCO2, VE/VCO2, PetCO2, and Borg scale rating. VCAP variables changed at each time point analyzed during the exercise test in both groups. VCAP can be used to analyze ventilatory parameters during exercise. All cardiorespiratory, spirometry, and VCAP variables differed between patients in the CFG and CG before, during, and after exercise.

Number of thoracotomies predicts impairment in lung function and exercise capacity in patients with congenital heart disease.

PubMed

Müller, Jan; Ewert, Peter; Hager, Alfred

2018-01-01

Many patients with congenital heart disease (CHD) require surgery to ensure survival into adulthood. But history of previous thoracotomies is associated with respiratory muscle weakness, impairments in chest wall compliance, and moderately to severely impaired lung function. This study evaluated the impact of thoracotomies on functional outcome in patients with CHD. In total 1372 adolescents and adults with CHD (32.4±11.5 years, 624 female), who underwent spirometry and cardiopulmonary exercise testing in our institution from January 2010 to August 2015, were analyzed. After adjusting for confounding variables, with every thoracotomy the prevalence for a restrictive ventilatory pattern increased by 1.8-fold (CI: 1.606-2.050; p<0.001). The number of thoracotomies had no direct influence on an impaired exercise capacity in a multivariate model, but with every percentage point increase in forced vital capacity probability of impaired exercise capacity diminished (OR: 0.944, CI: 0.933-0.955, p<0.001). There was a moderate correlation of forced vital capacity and peak oxygen uptake (r=0.464, p<0.001). After a follow-up of 2.1±1.6 years 21 patients had died. Survival was only related to age (p<0.001) and peak oxygen uptake (p<0.001) after considering together with thoracotomies, oxygen saturation at rest and forced vital capacity in a multivariate model. Independent of CHD complexity and other risk factors, multiple thoracotomies lead to restrictive lung pattern. It could be suggested that those limitations in forced vital capacity contribute to impairments in exercise capacity, which turned out to be the strongest predictor for survival. Copyright © 2017 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

The Prognostic Role of Ventilatory Inefficiency and Exercise Capacity in Idiopathic Pulmonary Fibrosis.

PubMed

Vainshelboim, Baruch; Oliveira, Jose; Fox, Benjamin Daniel; Kramer, Mordechai Reuven

2016-08-01

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and fatal interstitial lung disease associated with poor prognosis and limited effective treatment options. Reliable predictors of outcome in daily clinical practice are needed to determine high-risk patients for urgent lung transplantation referral. This study aimed to identify practical prognostic predictors of mortality using cardiopulmonary exercise testing (CPET) in IPF subjects. Thirty-four subjects with IPF (22 men and 12 women), median age 68 (range 50-81) y were prospectively studied. At baseline, all subjects were assessed with CPET and were followed up for 40 months from baseline. Receiver operating characteristic curve analysis was conducted to determine cut-off points of CPET variables for mortality, Cox regression analysis for survival using a log-rank test, and hazard ratio for death using a Wald test. Peak work rate <62 watts (P = .005), peak V̇O2 ≤13.8 mL/kg/min (P = .031), tidal volume reserve ≤0.48 L/breath (P = .010), minute ventilation to carbon dioxide (V̇E)/V̇CO2 ) ratio at the anaerobic threshold >34 (P = .02), and V̇E)/V̇O2 nadir >34 (P = .002) were detected as cut-off points associated with mortality. Non-survivor subjects were characterized by higher dyspnea levels, the presence of pulmonary hypertension assessed by echocardiography, pronounced inefficient ventilatory pattern, lower exercise capacity, and more severe desaturation during physical exertion. By the end of the study, 11 subjects (7 women and 4 men) died. Overall mean survival was 60%, 33.7 months (95% CI 30.2-37.2). This study provides simple, practical, and novel cut-off points for CPET as predictors of prognosis to identify high-risk IPF subjects. Impairment in exercise capacity and abnormal ventilatory responses during CPET were associated with poorer survival in IPF subjects. The findings suggest considering the use of CPET for IPF risk stratification and prediction of prognosis. (ClinicalTrials.gov registration NCT01499745.). Copyright © 2016 by Daedalus Enterprises.

Physiology of respiratory disturbances in muscular dystrophies

PubMed Central

Lo Mauro, Antonella

2016-01-01

Muscular dystrophy is a group of inherited myopathies characterised by progressive skeletal muscle wasting, including of the respiratory muscles. Respiratory failure, i.e. when the respiratory system fails in its gas exchange functions, is a common feature in muscular dystrophy, being the main cause of death, and it is a consequence of lung failure, pump failure or a combination of the two. The former is due to recurrent aspiration, the latter to progressive weakness of respiratory muscles and an increase in the load against which they must contract. In fact, both the resistive and elastic components of the work of breathing increase due to airway obstruction and chest wall and lung stiffening, respectively. The respiratory disturbances in muscular dystrophy are restrictive pulmonary function, hypoventilation, altered thoracoabdominal pattern, hypercapnia, dyspnoea, impaired regulation of breathing, inefficient cough and sleep disordered breathing. They can be present at different rates according to the type of muscular dystrophy and its progression, leading to different onset of each symptom, prognosis and degree of respiratory involvement. Key points A common feature of muscular dystrophy is respiratory failure, i.e. the inability of the respiratory system to provide proper oxygenation and carbon dioxide elimination. In the lung, respiratory failure is caused by recurrent aspiration, and leads to hypoxaemia and hypercarbia. Ventilatory failure in muscular dystrophy is caused by increased respiratory load and respiratory muscles weakness. Respiratory load increases in muscular dystrophy because scoliosis makes chest wall compliance decrease, atelectasis and fibrosis make lung compliance decrease, and airway obstruction makes airway resistance increase. The consequences of respiratory pump failure are restrictive pulmonary function, hypoventilation, altered thoracoabdominal pattern, hypercapnia, dyspnoea, impaired regulation of breathing, inefficient cough and sleep disordered breathing. Educational aims To understand the mechanisms leading to respiratory disturbances in patients with muscular dystrophy. To understand the impact of respiratory disturbances in patients with muscular dystrophy. To provide a brief description of the main forms of muscular dystrophy with their respiratory implications. PMID:28210319

Physiology of respiratory disturbances in muscular dystrophies.

PubMed

Lo Mauro, Antonella; Aliverti, Andrea

2016-12-01

Muscular dystrophy is a group of inherited myopathies characterised by progressive skeletal muscle wasting, including of the respiratory muscles. Respiratory failure, i.e . when the respiratory system fails in its gas exchange functions, is a common feature in muscular dystrophy, being the main cause of death, and it is a consequence of lung failure, pump failure or a combination of the two. The former is due to recurrent aspiration, the latter to progressive weakness of respiratory muscles and an increase in the load against which they must contract. In fact, both the resistive and elastic components of the work of breathing increase due to airway obstruction and chest wall and lung stiffening, respectively. The respiratory disturbances in muscular dystrophy are restrictive pulmonary function, hypoventilation, altered thoracoabdominal pattern, hypercapnia, dyspnoea, impaired regulation of breathing, inefficient cough and sleep disordered breathing. They can be present at different rates according to the type of muscular dystrophy and its progression, leading to different onset of each symptom, prognosis and degree of respiratory involvement. A common feature of muscular dystrophy is respiratory failure, i.e. the inability of the respiratory system to provide proper oxygenation and carbon dioxide elimination.In the lung, respiratory failure is caused by recurrent aspiration, and leads to hypoxaemia and hypercarbia.Ventilatory failure in muscular dystrophy is caused by increased respiratory load and respiratory muscles weakness.Respiratory load increases in muscular dystrophy because scoliosis makes chest wall compliance decrease, atelectasis and fibrosis make lung compliance decrease, and airway obstruction makes airway resistance increase.The consequences of respiratory pump failure are restrictive pulmonary function, hypoventilation, altered thoracoabdominal pattern, hypercapnia, dyspnoea, impaired regulation of breathing, inefficient cough and sleep disordered breathing. To understand the mechanisms leading to respiratory disturbances in patients with muscular dystrophy.To understand the impact of respiratory disturbances in patients with muscular dystrophy.To provide a brief description of the main forms of muscular dystrophy with their respiratory implications.

The effect of ventilatory muscle training on respiratory function and capacity in ambulatory and bed-ridden patients with neuromuscular disease.

PubMed

Gross, D; Meiner, Z

1993-08-01

Most patients with neuromuscular disease develop muscle weakness, including the ventilatory muscles leading to respiratory difficulty and, at times, respiratory insufficiency. We studied the effect of ventilatory muscle training on the ventilatory function and capacity of patients with various types of neuromuscular disease. The ambulatory patients were divided into three major groups. Group I (n = 6) patients with motor neuron disease (MND), such as amyotrophic latera sclerosis; Group II (n = 11) patients with myoneural junction disease (MNJ), such as myasthenia gravis and: Group III (n = 7) patients with muscle diseases such as progressive muscular disease. Patients were evaluated for their neuromuscular diagnosis and status of the disease. A complete physical examination and the various neuromuscular tests were performed. A complete respiratory evaluation was applied: pulmonary function tests (PFT), maximum inspiratory pressure (MIP). Patients then started ventilatory muscle training by resistive breathing, as a prophylactic treatment, for 10 min, three times daily, with a resistance which would induce fatigue. All tests were repeated every six weeks, and the results were as follow: forced vital capacity (FVC) changed from 38.8 +/- 12.3 to 53.2 +/- 9.6% (NS) of predicted value in group I, from 49.8 +/- 8.7 to 66.1 +/- 7.5% (p < 0.002) in group II, and from 47.0 +/- 7.5 to 53.3 +/- 7.6% (p < 0.04) in group III. Forced expiratory volume in one second (FEV1) was 34.8 +/- 11.0, 46.3 +/- 5, and 45.1 +/- 9% for the three groups, respectively, and did not change with training.(ABSTRACT TRUNCATED AT 250 WORDS)

Muscular, cardiac, ventilatory and metabolic dysfunction in patients with multiple sclerosis: Implications for screening, clinical care and endurance and resistance exercise therapy, a scoping review.

PubMed

Wens, Inez; Eijnde, Bert O; Hansen, Dominique

2016-08-15

In the treatment of multiple sclerosis (MS), exercise training is now considered a cornerstone. However, most clinicians tend to focus on neurologic deficits only, and thus prefer to prescribe rehabilitation programs specifically to counteract these deficits. However, the present comprehensive review shows that patients with MS (pwMS) also experience significant muscular, cardiac, ventilatory and metabolic dysfunction, which significantly contribute, next to neurologic deficits, to exercise intolerance. In addition, these anomalies also might increase the risk for frequent hospitalization and morbidity and can reduce life expectancy. Unfortunately, the impact of exercise intervention on these anomalies in pwMS are mostly unknown. Therefore, it is suggested that pwMS should be screened systematically for muscular, cardiac, ventilatory and metabolic function during exercise testing. The detection of such anomalies should lead to adaptations and optimisation of exercise training prescription and clinical care/medical treatment of pwMS. In addition, future studies should focus on the impact of exercise intervention on muscular, cardiac, ventilatory and metabolic (dys)function in pwMS, to contribute to improved treatment and care. Copyright © 2016. Published by Elsevier B.V.

Use of cardiopulmonary exercise testing to assess early ventilatory changes related to occupational particulate matter

PubMed Central

Chao, T.P.; Sperandio, E.F.; Ostolin, T.L.V.P.; Almeida, V.R.; Romiti, M.; Gagliardi, A.R.T.; Arantes, R.L.; Dourado, V.Z.

2018-01-01

Spirometry has been used as the main strategy for assessing ventilatory changes related to occupational exposure to particulate matter (OEPM). However, in some cases, as one of its limitations, it may not be sensitive enough to show abnormalities before extensive damage, as seen in restrictive lung diseases. Therefore, we hypothesized that cardiopulmonary exercise testing (CPET) may be better than spirometry to detect early ventilatory impairment caused by OEPM. We selected 135 male workers with at least one year of exposure. After collection of self-reported socioeconomic status, educational level, and cardiovascular risk data, participants underwent spirometry, CPET, body composition assessment (bioelectrical impedance), and triaxial accelerometry (for level of physical activity in daily life). CPET was performed using a ramp protocol on a treadmill. Metabolic, cardiovascular, ventilatory, and submaximal relationships were measured. We compared 52 exposed to 83 non-exposed workers. Multiple linear regressions were developed using spirometry and CPET variables as outcomes and OEPM as the main predictor, and adjusted by the main covariates. Our results showed that OEPM was associated with significant reductions in peak minute ventilation, peak tidal volume, and breathing reserve index. Exposed participants presented shallower slope of ΔVT/ΔlnV̇E (breathing pattern), i.e., increased tachypneic breathing pattern. The OEPM explained 7.4% of the ΔVT/ΔlnV̇E variability. We found no significant influence of spirometric indices after multiple linear regressions. We conclude that CPET might be a more sensitive feature of assessing early pulmonary impairment related to OEPM. Our cross-sectional results suggested that CPET is a promising tool for the screening of asymptomatic male workers. PMID:29590255

Prenatal nicotinic exposure augments cardiorespiratory responses to activation of bronchopulmonary C-fibers

PubMed Central

Zhuang, Jianguo; Zhao, Lei; Zang, Na

2015-01-01

Rat pups prenatally exposed to nicotine (PNE) present apneic (lethal ventilatory arrest) responses during severe hypoxia. To clarify whether these responses are of central origin, we tested PNE effects on ventilation and diaphragm electromyography (EMGdi) during hypoxia in conscious rat pups. PNE produced apnea (lethal ventilatory arrest) identical to EMGdi silencing during hypoxia, indicating a central origin of this apneic response. We further asked whether PNE would sensitize bronchopulmonary C-fibers (PCFs), a key player in generating central apnea, with increase of the density and transient receptor potential cation channel subfamily V member 1 (TRPV1) expression of C-fibers/neurons in the nodose/jugular (N/J) ganglia and neurotrophic factors in the airways and lungs. We compared 1) ventilatory and pulmonary C-neural responses to right atrial bolus injection of capsaicin (CAP, 0.5 μg/kg), 2) bronchial substance P-immunoreactive (SP-IR) fiber density, 3) gene and protein expressions of TRPV1 in the ganglia, and 4) nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) protein in bronchoalveolar lavage fluid (BALF) and TrkA and TrkB genes in the ganglia between control and PNE pups. PNE markedly strengthened the PCF-mediated apneic response to CAP via increasing pulmonary C-neural sensitivity. PNE also enhanced bronchial SP-IR fiber density and N/J ganglia neural TRPV1 expression associated with increased gene expression of TrkA in the N/G ganglia and decreased NGF and BDNF in BALF. Our results suggest that PNE enhances PCF sensitivity likely through increasing PCF density and TRPV1 expression via upregulation of neural TrkA and downregulation of pulmonary BDNF, which may contribute to the PNE-promoted central apnea (lethal ventilatory arrest) during hypoxia. PMID:25747962

The ALIEN study: incidence and outcome of acute respiratory distress syndrome in the era of lung protective ventilation.

PubMed

Villar, Jesús; Blanco, Jesús; Añón, José Manuel; Santos-Bouza, Antonio; Blanch, Lluís; Ambrós, Alfonso; Gandía, Francisco; Carriedo, Demetrio; Mosteiro, Fernando; Basaldúa, Santiago; Fernández, Rosa Lidia; Kacmarek, Robert M

2011-12-01

While our understanding of the pathogenesis and management of acute respiratory distress syndrome (ARDS) has improved over the past decade, estimates of its incidence have been controversial. The goal of this study was to examine ARDS incidence and outcome under current lung protective ventilatory support practices before and after the diagnosis of ARDS. This was a 1-year prospective, multicenter, observational study in 13 geographical areas of Spain (serving a population of 3.55 million at least 18 years of age) between November 2008 and October 2009. Subjects comprised all consecutive patients meeting American-European Consensus Criteria for ARDS. Data on ventilatory management, gas exchange, hemodynamics, and organ dysfunction were collected. A total of 255 mechanically ventilated patients fulfilled the ARDS definition, representing an incidence of 7.2/100,000 population/year. Pneumonia and sepsis were the most common causes of ARDS. At the time of meeting ARDS criteria, mean PaO(2)/FiO(2) was 114 ± 40 mmHg, mean tidal volume was 7.2 ± 1.1 ml/kg predicted body weight, mean plateau pressure was 26 ± 5 cmH(2)O, and mean positive end-expiratory pressure (PEEP) was 9.3 ± 2.4 cmH(2)O. Overall ARDS intensive care unit (ICU) and hospital mortality was 42.7% (95%CI 37.7-47.8) and 47.8% (95%CI 42.8-53.0), respectively. This is the first study to prospectively estimate the ARDS incidence during the routine application of lung protective ventilation. Our findings support previous estimates in Europe and are an order of magnitude lower than those reported in the USA and Australia. Despite use of lung protective ventilation, overall ICU and hospital mortality of ARDS patients is still higher than 40%.

Respiratory system mechanics in acute respiratory distress syndrome.

PubMed

Kallet, Richard H; Katz, Jeffrey A

2003-09-01

Respiratory mechanics research is important to the advancement of ARDS management. Twenty-eight years ago, research on the effects of PEEP and VT indicated that the lungs of ARDS patients did not behave in a manner consistent with homogenously distributed lung injury. Both Suter and colleagues] and Katz and colleagues reported that oxygenation continued to improve as PEEP increased (suggesting lung recruitment), even though static Crs decreased and dead-space ventilation increased (suggesting concurrent lung overdistension). This research strongly suggested that without VT reduction, the favorable effects of PEEP on lung recruitment are offset by lung overdistension at end-inspiration. The implications of these studies were not fully appreciated at that time, in part because the concept of ventilator-associated lung injury was in its nascent state. Ten years later. Gattinoni and colleagues compared measurements of static pressure-volume curves with FRC and CT scans of the chest in ARDS. They found that although PEEP recruits collapsed (primarily dorsal) lung segments, it simultaneously causes overdistension of non-dependent, inflated lung regions. Furthermore, the specific compliance of the aerated, residually healthy lung tissue is essentially normal. The main implication of these findings is that traditional mechanical ventilation practice was injecting excessive volumes of gas into functionally small lungs. Therefore, the emblematic low static Crs measured in ARDS reflects not only surface tension phenomena and recruitment of collapsed airspaces but also overdistension of the remaining healthy lung. The studies reviewed in this article support the concept that lung injury in ARDS is heterogeneously distributed, with resulting disparate mechanical stresses, and indicate the additional complexity from alterations in chest wall mechanics. Most of these studies, however, were published before lung-protective ventilation. Therefore, further studies are needed to refine the understanding of the mechanical effects of lung-protective ventilation. Although low-VT ventilation is becoming a standard of care for ARDS patients, many issues remain unresolved; among them are the role of PEEP and recruitment maneuvers in either preventing or promoting lung injury and the effects of respiratory rate and graded VT reduction on mechanical stress in the lungs. The authors believe that advances in mechanical ventilation that may further improve patient outcomes are likely to come from more sophisticated monitoring capabilities (ie, the ability to measure P1 or perhaps Cslice) than from the creation of new modes of ventilatory support.

EARLY STABILIZING ALVEOLAR VENTILATION PREVENTS ARDS- A NOVEL TIMING-BASED VENTILATORY INTERVENTION TO AVERT LUNG INJURY

PubMed Central

Roy, Shreyas; Sadowitz, Benjamin; Andrews, Penny; Gatto, Louis; Marx, William; Ge, Lin; Wang, Guirong; Lin, Xin; Dean, David A.; Kuhn, Michael; Ghosh, Auyon; Satalin, Joshua; Snyder, Kathy; Vodovotz, Yoram; Nieman, Gary; Habashi, Nader

2012-01-01

Background Established ARDS is often refractory to treatment. Clinical trials have demonstrated modest treatment effects, and mortality remains high. Ventilator strategies must be developed to prevent ARDS. Hypothesis Early ventilatory intervention will block progression to ARDS if the ventilator mode: 1) maintains alveolar stability and 2) reduces pulmonary edema formation. Methods Yorkshire Pigs (38–45kg) were anaesthetized and subjected to "2-hit" Ischemia-Reperfusion and Peritoneal Sepsis. Following injury, animals were randomized into two groups: Early Preventative Ventilation (Airway Pressure Release Ventilation- APRV) vs. Non-Preventative Ventilation (NPV) and followed for 48hr. All animals received anesthesia, antibiotics, and fluid/vasopressor therapy per Surviving Sepsis Campaign. Ventilation parameters: 1) NPV Group - Tidal volume (Vt): 10cc/kg + PEEP- 5 cm/H2O volume-cycled mode, 2) APRV Group - Vt: 10–15 cc/kg; Phigh, Plow, Thigh, Tlow were titrated for optimal alveolar stability. Physiologic data and plasma were collected throughout the 48hr study period, followed by BAL and necropsy. Results APRV prevented development of ARDS (p<0.001 vs NPV) by PaO2/FiO2 ratio. Quantitative histological scoring showed APRV prevented lung tissue injury (p<0.001 vs. NPV). BALF showed APRV lowered total protein and IL-6, while preserving surfactant proteins A & B (p<0.05 vs. NPV). APRV significantly lowered lung water (p<0.001 vs. NPV). Plasma IL-6 concentrations were similar between groups. Conclusions Early preventative mechanical ventilation with APRV blocked ARDS development, preserved surfactant proteins, and reduced pulmonary inflammation and edema, despite systemic inflammation similar to NPV. These data suggest early preventative ventilation strategies stabilizing alveoli and reducing pulmonary edema can attenuate ARDS after ischemia-reperfusion-sepsis. PMID:22846945

Effect of different ventilatory strategies on local and systemic cytokine production in intact swine lungs in vivo.

PubMed

Myrianthefs, P; Boutzouka, E; Venetsanou, K; Papalois, A; Kouloukousa, M; Kittas, C; Baltopoulos, G

2006-05-01

The purpose of the study was to investigate the effect of different ventilatory strategies on local and systemic cytokine production in swine with intact lungs in vivo after 4 h of mechanical ventilation. Twenty-five swine were anesthetized and then randomized into five groups (n = 5): (1) low tidal volume zero PEEP (LVZP); (2) medium tidal volume zero PEEP (MVZP); (3) high tidal volume zero PEEP (HVZP); (4) low tidal volume PEEP (LVP); (4) high tidal volume PEEP (HVP). Respiratory rate was adjusted to maintain normocapnia and fraction of inspired oxygen (FiO2) was 1.0. TNF-alpha and IL-10 were measured in BALF and serum at baseline, 2 h, and 4 h of MV. One animal in LVZP (2 h) and two in HVP (3 h) group died before the end of the experiment. TNF-alpha level in BALF was significantly higher in LVZP and LVP at 4 h compared to baseline and the other groups. IL-10 level in BALF was significantly higher in LVP at 4h compared to baseline and the other groups. There was a statistically significant increase in serum TNF-alpha levels at 4 h in LVP group compared to baseline and the other groups at 4 h. There was statistically significant increase in serum IL-10 levels in HVZP and LVP groups at 2 and 4 h which was significantly higher compared to the other groups at 4 h. Our results show that a) low volume MV may induce local and systemic pro- and anti-inflammatory cytokine increase b) in the presence of pro-inflammatory cytokine response there is also an anti-inflammatory response in the same compartment (lungs, circulation). c) There maybe loss of alveolar-to-systemic cytokine compartmentalization.

Ventilatory responses to acute and chronic hypoxia are altered in female but not male Paskin-deficient mice.

PubMed

Soliz, Jorge; Soulage, Christophe; Borter, Emanuela; van Patot, Martha Tissot; Gassmann, Max

2008-08-01

Proteins harboring a Per-Arnt-Sim (PAS) domain are versatile and allow archaea, bacteria, and plants to sense oxygen partial pressure, as well as light intensity and redox potential. A PAS domain associated with a histidine kinase domain is found in FixL, the oxygen sensor molecule of Rhizobium species. PASKIN is the mammalian homolog of FixL, but its function is far from being understood. Using whole body plethysmography, we evaluated the ventilatory response to acute and chronic hypoxia of homozygous deficient male and female PASKIN mice (Paskin-/-). Although only slight ventilatory differences were found in males, female Paskin-/- mice increased ventilatory response to acute hypoxia. Unexpectedly, females had an impaired ability to reach ventilatory acclimatization in response to chronic hypoxia. Central control of ventilation occurs in the brain stem respiratory centers and is modulated by catecholamines via tyrosine hydroxylase (TH) activity. We observed that TH activity was altered in male and female Paskin-/- mice. Peripheral chemoreceptor effects on ventilation were evaluated by exposing animals to hyperoxia (Dejours test) and domperidone, a peripheral ventilatory stimulant drug directly affecting the carotid sinus nerve discharge. Male and female Paskin-/- had normal peripheral chemosensory (carotid bodies) responses. In summary, our observations suggest that PASKIN is involved in the central control of hypoxic ventilation, modulating ventilation in a gender-dependent manner.

Hyperinflation and intrinsic positive end-expiratory pressure: less room to breathe.

PubMed

Krieger, Bruce P

2009-01-01

Clinically, the symptoms and limited exercise capabilities of patients with chronic obstructive pulmonary disease (COPD) correlate better with changes in lung volumes than with airflow measurements. The realization of the clinical importance of hyperinflation has been overshadowed for decades by the use of forced expiratory volume during 1 s (FEV(1)) and the ratio of the FEV(1) to the forced expiratory vital capacity (FEV(1)/FVC) to categorize the severity and progression of COPD. Hyperinflation is defined as an elevation in the end-expiratory lung volume or functional residual capacity. When severe hyperinflation encroaches upon inspiratory capacity and limits vital capacity, it results in elevated intrinsic positive end-expiratory pressure (PEEPi) that places the diaphragm at a mechanical disadvantage and increases the work of breathing. Severe hyperinflation is the major physiologic cause of the resulting hypercarbic respiratory failure and patients' inability to transition (i.e. wean) from mechanical ventilatory support to spontaneous breathing. This paper reviews the basic physiologic principles of hyperinflation and its clinical manifestations as demonstrated by PEEPi. Also reviewed are the adverse effects of hyperinflation and PEEPi in critically ill patients with COPD, and methods for minimizing or counterbalancing these effects. Copyright 2009 S. Karger AG, Basel.

Physiological and lavage fluid cytological and biochemical endpoints of toxicity in the rat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lehnert, B.E.

1992-01-01

Exposure of the respiratory tract to toxic materials can result in a variety of physiologic disturbances that can serve as endpoints of toxicity. In addition to a brief review of commonly assessed physiologic endpoints, attention is given in the first component of this report to the use of both nose breathing and mouth'' breathing rats in toxicity studies that involve measurements of ventilatory functional changes in response to test atmospheres. Additionally, the usefulness of maximum oxygen consumption, or VO[sub 2max], as a physiologic endpoint of toxicity that uses exercising rats after exposure to test atmospheres is described, along with anmore » introduction to post-exposure exercise as an important behavioral activity that can markedly impact on the severity of acute lung injury caused by pneumoedematogenic materials. The second component of this report focuses on bronchoalveolar lavage and cytological and biochemical endpoints that can be assessed in investigations of the toxicities of test materials. As will be shown herein, some of the biochemical endpoints of toxicity, especially, can sensitively detect subtle injury to the lower respiratory tract that may escape detection by changes in some other conventional endpoints of toxicity, including lung gravimetric increases and histopathological alterations.« less

Physiological and lavage fluid cytological and biochemical endpoints of toxicity in the rat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lehnert, B.E.

1992-12-31

Exposure of the respiratory tract to toxic materials can result in a variety of physiologic disturbances that can serve as endpoints of toxicity. In addition to a brief review of commonly assessed physiologic endpoints, attention is given in the first component of this report to the use of both nose breathing and ``mouth`` breathing rats in toxicity studies that involve measurements of ventilatory functional changes in response to test atmospheres. Additionally, the usefulness of maximum oxygen consumption, or VO{sub 2max}, as a physiologic endpoint of toxicity that uses exercising rats after exposure to test atmospheres is described, along with anmore » introduction to post-exposure exercise as an important behavioral activity that can markedly impact on the severity of acute lung injury caused by pneumoedematogenic materials. The second component of this report focuses on bronchoalveolar lavage and cytological and biochemical endpoints that can be assessed in investigations of the toxicities of test materials. As will be shown herein, some of the biochemical endpoints of toxicity, especially, can sensitively detect subtle injury to the lower respiratory tract that may escape detection by changes in some other conventional endpoints of toxicity, including lung gravimetric increases and histopathological alterations.« less

Physiology of breathlessness associated with pleural effusions

PubMed Central

Thomas, Rajesh; Jenkins, Susan; Eastwood, Peter R.; Lee, Y.C. Gary; Singh, Bhajan

2015-01-01

Purpose of review Pleural effusions have a major impact on the cardiorespiratory system. This article reviews the pathophysiological effects of pleural effusions and pleural drainage, their relationship with breathlessness, and highlights key knowledge gaps. Recent findings The basis for breathlessness in pleural effusions and relief following thoracentesis is not well understood. Many existing studies on the pathophysiology of breathlessness in pleural effusions are limited by small sample sizes, heterogeneous design and a lack of direct measurements of respiratory muscle function. Gas exchange worsens with pleural effusions and improves after thoracentesis. Improvements in ventilatory capacity and lung volumes following pleural drainage are small, and correlate poorly with the volume of fluid drained and the severity of breathlessness. Rather than lung compression, expansion of the chest wall, including displacement of the diaphragm, appears to be the principle mechanism by which the effusion is accommodated. Deflation of the thoracic cage and restoration of diaphragmatic function after thoracentesis may improve diaphragm effectiveness and efficiency, and this may be an important mechanism by which breathlessness improves. Effusions do not usually lead to major hemodynamic changes, but large effusions may cause cardiac tamponade and ventricular diastolic collapse. Patients with effusions can have impaired exercise capacity and poor sleep quality and efficiency. Summary Pleural effusions are associated with abnormalities in gas exchange, respiratory mechanics, respiratory muscle function and hemodynamics, but the association between these abnormalities and breathlessness remains unclear. Prospective studies should aim to identify the key mechanisms of effusion-related breathlessness and predictors of improvement following pleural drainage. PMID:25978627

Physiology of breathlessness associated with pleural effusions.

PubMed

Thomas, Rajesh; Jenkins, Susan; Eastwood, Peter R; Lee, Y C Gary; Singh, Bhajan

2015-07-01

Pleural effusions have a major impact on the cardiorespiratory system. This article reviews the pathophysiological effects of pleural effusions and pleural drainage, their relationship with breathlessness, and highlights key knowledge gaps. The basis for breathlessness in pleural effusions and relief following thoracentesis is not well understood. Many existing studies on the pathophysiology of breathlessness in pleural effusions are limited by small sample sizes, heterogeneous design and a lack of direct measurements of respiratory muscle function. Gas exchange worsens with pleural effusions and improves after thoracentesis. Improvements in ventilatory capacity and lung volumes following pleural drainage are small, and correlate poorly with the volume of fluid drained and the severity of breathlessness. Rather than lung compression, expansion of the chest wall, including displacement of the diaphragm, appears to be the principle mechanism by which the effusion is accommodated. Deflation of the thoracic cage and restoration of diaphragmatic function after thoracentesis may improve diaphragm effectiveness and efficiency, and this may be an important mechanism by which breathlessness improves. Effusions do not usually lead to major hemodynamic changes, but large effusions may cause cardiac tamponade and ventricular diastolic collapse. Patients with effusions can have impaired exercise capacity and poor sleep quality and efficiency. Pleural effusions are associated with abnormalities in gas exchange, respiratory mechanics, respiratory muscle function and hemodynamics, but the association between these abnormalities and breathlessness remains unclear. Prospective studies should aim to identify the key mechanisms of effusion-related breathlessness and predictors of improvement following pleural drainage.

MULTI-FREQUENCY OSCILLATORY VENTILATION IN THE PREMATURE LUNG: EFFECTS ON GAS EXCHANGE, MECHANICS, AND VENTILATION DISTRIBUTION

PubMed Central

Kaczka, David W.; Herrmann, Jacob; Zonneveld, C. Elroy; Tingay, David G.; Lavizzari, Anna; Noble, Peter B.; Pillow, J. Jane

2015-01-01

Background Despite the theoretical benefits of high-frequency oscillatory ventilation (HFOV) in preterm infants, systematic reviews of randomized clinical trials do not confirm improved outcomes. We hypothesized that oscillating a premature lung with multiple frequencies simultaneously would improve gas exchange compared to traditional single-frequency oscillatory ventilation (SFOV). The goal of this study was to develop a novel method for HFOV, termed ‘multi-frequency oscillatory ventilation’ (MFOV), which relies on a broadband flow waveform more suitable for the heterogeneous mechanics of the immature lung. Methods Thirteen intubated preterm lambs were randomized to either SFOV or MFOV for 1 hour, followed by crossover to the alternative regimen for 1 hour. The SFOV waveform consisted of a pure sinusoidal flow at 5 Hz, while the customized MFOV waveform consisted of a 5 Hz fundamental with additional energy at 10 and 15 Hz. Per standardized protocol, mean pressure at airway opening (P̅ao) and inspired O2 fraction were adjusted as needed, and root mean square of the delivered oscillatory volume waveform (Vrms) was adjusted 15-minute intervals. A ventilatory cost function for SFOV and MFOV was defined as VC=(Vrms2PaCO2)Wt−1, where Wt denotes body weight. Results Averaged over all time points, MFOV resulted in significantly lower VC (246.9±6.0 vs. 363.5±15.9 mL2 mmHg kg−1) and P̅ao (12.8±0.3 vs. 14.1±0.5 cmH2O) compared to SFOV, suggesting more efficient gas exchange and enhanced lung recruitment at lower mean airway pressures. Conclusions Oscillation with simultaneous multiple frequencies may be a more efficient ventilator modality in premature lungs compared to traditional single-frequency HFOV. PMID:26495977

Pulmonary NO and C18O2 uptake during pressure-induced lung expansion in rabbits.

PubMed

Heller, Hartmut; Schuster, Klaus-Dieter

2007-01-01

In artificially ventilated animals we investigated the dependence of the pulmonary diffusing capacities of nitric oxide (NO) and doubly 18O-labeled carbon dioxide (DLNO, DLC18O2) on lung expansion with respect to ventilator-driven increases in intrapulmonary pressure. For this purpose we applied computerized single-breath experiments to 11 anesthetized paralyzed rabbits (weight 2.8-3.8 kg) at various alveolar volumes (45-72 ml) by studying the almost entire inspiratory limb of the respective pressure/volume curves (intrapulmonary pressure: 6-27 cmH2O). The animals were ventilated with room air, employing a computerized ventilatory servo-system that we designed to maintain mechanical ventilation and to execute the particular lung function tests automatically. Each single-breath maneuver was started from residual volume (13.5+/-2 ml, mean+/-SD) by inflating the rabbit lungs with 35-55 ml indicator gas mixture containing 0.05% NO in N2 or 0.9% C18O2 in N2. Alveolar partial pressures of NO and C18O2 were measured by respiratory mass spectrometry. Values of DLNO and DLC18O2 ranged between 1.55 and 2.49 ml/(mmHg min) and 11.7 and 16.6 ml/(mmHg min), respectively. Linear regression analyses yielded a significant increase in DLNO with simultaneous increase in alveolar volume (P<0.005) and intrapulmonary pressure (P<0.023) whereas DLC18O2 was not improved. Our results suggest that the ventilator-driven lung expansion impaired the C18O2 blood uptake conductance, finally compensating for the beneficial effect of the increase in alveolar volume on DLC18O2 values.

The critically ill injured patient.

PubMed

Cereda, Maurizio; Weiss, Yoram G; Deutschman, Clifford S

2007-03-01

Patients admitted to the ICU after severe trauma require frequent procedures in the operating room, particularly in cases where a damage control strategy is used. The ventilatory management of these patients in the operating room can be particularly challenging. These patients often have severely impaired respiratory mechanics because of acute lung injury and abdominal compartment syndrome. Consequently, the pressure and flow generation capabilities of standard anesthesia ventilators may be inadequate to support ventilation and gas exchange. This article presents the problems that may be encountered in patients who have severe abdominal and lung injuries, and the current management concepts used in caring for these patients in the critical care setting, to provide guidelines for the anesthetist faced with these patients in the operating room.

Aerophagia and anesthesia: an unusual cause of ventilatory insufficiency in a neonate.

PubMed

Lalwani, Kirk

2005-10-01

We describe a healthy neonate with abdominal distention, inadequate ventilation, and delayed extubation during anesthesia for minor surgery. Following rectal decompression and successful extubation, extreme abdominal distention recurred postoperatively after ingestion of clear fluids. We elicited a history of frequent and excessive flatus from the parents, and abdominal radiography revealed distended loops of small bowel with small lung volumes suggestive of aerophagia. The differential diagnosis of aerophagia is reviewed, the anesthetic implications discussed, and relevant literature pertaining to this condition summarized.

Pulmonary function test in formalin exposed and nonexposed subjects: A comparative study

PubMed Central

Uthiravelu, P.; Saravanan, A.; Kumar, C. Kishor; Vaithiyanandane, V.

2015-01-01

Background: The main function of the lung is gas exchange, which can be assessed in several ways. A spirometer measures the flow and the volumes of the inspired and expired air. The thoracic and abdominal muscle strength plays an important role in pulmonary function and diffusing lung capacity. Aims and Objectives: The aim of this study was to assess the effects of formalin exposure on the pulmonary function to compare with healthy individuals. To assess the chronic effects of formalin exposure on Pulmonary function tests (PFTs) in the faculties, lab technicians and attender of the Department of Anatomy and Pathology of SRM Medical Hospital and Research Centre, Kattankulathur. Materials and Methods: This prospective study was carried out in 50 healthy formalin exposed subjects (at least 5 years exposure) from Department of Anatomy and Pathology of SRM Medical College Hospital and Research Centre, Kattankulathur and 50 healthy controls of same age group of this study were included after obtaining ethical clearance and consent ‘Easy One Pro Spirometer (Ndd Medical Technologies, Cheshire SK 101LT, United Kingdom) was used to find out the PFT. Results: Student's t-test was applied to compare the PFT parameters between formalin exposed and formalin nonexposed group. There was a significant difference in mean and standard deviation of pulmonary parameters with the P < 0.005 in formalin exposed, which shows that they have lesser ventilatory drive. Conclusion: The formalin exposed subjects in our study presented with a mixed disorder of both obstructive and restrictive type. We also found that there was a negative correlation of pulmonary function with that of the degree and duration of exposure to formalin. PMID:26015743

Does nebulized fentanyl relieve dyspnea during exercise in healthy man?

PubMed Central

Kotrach, Houssam G.; Bourbeau, Jean

2015-01-01

Few therapies exist for the relief of dyspnea in restrictive lung disorders. Accumulating evidence suggests that nebulized opioids selective for the mu-receptor subtype may relieve dyspnea by modulating intrapulmonary opioid receptor activity. Our respective primary and secondary objectives were to test the hypothesis that nebulized fentanyl (a mu-opioid receptor agonist) relieves dyspnea during exercise in the presence of abnormal restrictive ventilatory constraints and to identify the physiological mechanisms of this improvement. In a randomized, double-blind, placebo-controlled crossover study, we examined the effect of 250 μg nebulized fentanyl, chest wall strapping (CWS), and their interaction on detailed physiological and perceptual responses to constant work rate cycle exercise (85% of maximum incremental work rate) in 14 healthy, fit young men. By design, CWS decreased vital capacity by ∼20% and mimicked the negative consequences of a mild restrictive lung disorder on exercise endurance time and on dyspnea, breathing pattern, dynamic operating lung volumes, and diaphragmatic electromyographic and respiratory muscle function during exercise. Compared with placebo under both unrestricted control and CWS conditions, nebulized fentanyl had no effect on exercise endurance time, integrated physiological response to exercise, sensory intensity, unpleasantness ratings of exertional dyspnea. Our results do not support a role for intrapulmonary opioids in the neuromodulation of exertional dyspnea in health nor do they provide a physiological rationale for the use of nebulized fentanyl in the management of dyspnea due to mild restrictive lung disorders, specifically those arising from abnormalities of the chest wall and not affiliated with airway inflammation. PMID:26031762

Spirometry, Static Lung Volumes, and Diffusing Capacity.

PubMed

Vaz Fragoso, Carlos A; Cain, Hilary C; Casaburi, Richard; Lee, Patty J; Iannone, Lynne; Leo-Summers, Linda S; Van Ness, Peter H

2017-09-01

Spirometric Z-scores from the Global Lung Initiative (GLI) rigorously account for age-related changes in lung function and are thus age-appropriate when establishing spirometric impairments, including a restrictive pattern and air-flow obstruction. However, GLI-defined spirometric impairments have not yet been evaluated regarding associations with static lung volumes (total lung capacity [TLC], functional residual capacity [FRC], and residual volume [RV]) and gas exchange (diffusing capacity). We performed a retrospective review of pulmonary function tests in subjects ≥40 y old (mean age 64.6 y), including pre-bronchodilator measures for: spirometry ( n = 2,586), static lung volumes by helium dilution with inspiratory capacity maneuver ( n = 2,586), and hemoglobin-adjusted single-breath diffusing capacity ( n = 2,508). Using multivariable linear regression, adjusted least-squares means (adj LS Means) were calculated for TLC, FRC, RV, and hemoglobin-adjusted single-breath diffusing capacity. The adj LS Means were expressed with and without height-cubed standardization and stratified by GLI-defined spirometry, including normal ( n = 1,251), restrictive pattern ( n = 663), and air-flow obstruction (mild, [ n = 128]; moderate, [ n = 150]; and severe, [ n = 394]). Relative to normal spirometry, restrictive-pattern had lower adj LS Means for TLC, FRC, RV, and hemoglobin-adjusted single-breath diffusing capacity ( P ≤ .001). Conversely, relative to normal spirometry, mild, moderate, and severe air-flow obstruction had higher adj LS Means for FRC and RV ( P < .001). However, only mild and moderate air-flow obstruction had higher adj LS Means for TLC ( P < .001), while only moderate and severe air-flow obstruction had higher adj LS Means for RV/TLC ( P < .001) and lower adj LS Means for hemoglobin-adjusted single-breath diffusing capacity ( P < .001). Notably, TLC (calculated as FRC + inspiratory capacity) was not increased in severe air-flow obstruction ( P ≥ .11) because inspiratory capacity decreased with increasing air-flow obstruction ( P < .001), thus opposing the increased FRC ( P < .001). Finally, P values were similar whether adj LS Means were height-cubed standardized. A GLI-defined spirometric restrictive pattern is strongly associated with a restrictive ventilatory defect (decreased TLC, FRC, and RV), while GLI-defined spirometric air-flow obstruction is strongly associated with hyperinflation (increased FRC) and air trapping (increased RV and RV/TLC). Both spirometric impairments were strongly associated with impaired gas exchange (decreased hemoglobin-adjusted single-breath diffusing capacity). Copyright © 2017 by Daedalus Enterprises.

Diaphragmatic mobility: relationship with lung function, respiratory muscle strength, dyspnea, and physical activity in daily life in patients with COPD.

PubMed

Rocha, Flávia Roberta; Brüggemann, Ana Karla Vieira; Francisco, Davi de Souza; Medeiros, Caroline Semprebom de; Rosal, Danielle; Paulin, Elaine

2017-01-01

To evaluate diaphragmatic mobility in relation to lung function, respiratory muscle strength, dyspnea, and physical activity in daily life (PADL) in patients with COPD. We included 25 patients with COPD, classified according to the Global Initiative for Chronic Obstructive Lung Disease criteria, and 25 healthy individuals. For all of the participants, the following were evaluated: anthropometric variables, spirometric parameters, respiratory muscle strength, diaphragmatic mobility (by X-ray), PADL, and the perception of dyspnea. In the COPD group, diaphragmatic mobility was found to correlate with lung function variables, inspiratory muscle strength, and the perception of dyspnea, whereas it did not correlate with expiratory muscle strength or PADL. In patients with COPD, diaphragmatic mobility seems to be associated with airway obstruction and lung hyperinflation, as well as with ventilatory capacity and the perception of dyspnea, although not with PADL. Avaliar a relação da mobilidade diafragmática com a função pulmonar, força muscular respiratória, dispneia e atividade física de vida diária (AFVD) em pacientes com DPOC. Foram avaliados 25 pacientes com diagnóstico de DPOC, classificados de acordo com critérios da Global Initiative for Chronic Obstructive Lung Disease, e 25 indivíduos saudáveis. Todos foram submetidos às seguintes avaliações: mensuração antropométrica, espirometria, força muscular respiratória, mobilidade diafragmática (por radiografia), AFVD e percepção de dispneia. No grupo DPOC, houve correlações da mobilidade diafragmática com variáveis de função pulmonar, força muscular inspiratória e percepção de dispneia. Não houve correlações da mobilidade diafragmática com força muscular expiratória e AFVD. A mobilidade diafragmática parece estar associada tanto com a obstrução das vias aéreas quanto com a hiperinsuflação pulmonar em pacientes com DPOC, assim como com a capacidade ventilatória e percepção de dispneia, mas não com AFVD.

[Diaphragm pacing for the ventilatory support of the quadriplegic patients with respiratory paralysis].

PubMed

Cheng, H; Wang, L S; Pan, H C; Shoung, H M; Lee, L S

1992-02-01

Electrical stimulation of the phrenic nerve to pace the diaphragm in patients with chronic ventilatory insufficiency has been an established therapeutic modality since William W.L. Glenn first described using radiofrequency signals in 1978 to stimulate the phrenic nerves. Before this event, patients who were ventilator-dependent and thus bedridden because of respiratory paralysis associated with quadriplegia usually anticipated little chance for physical or psychosocial rehabilitation. Two cases of C1-C2 subluxtion with cord injury and chronic ventilatory insufficiency were implanted at VGH-Taipei with diaphragm pacemaker in 1988. Postoperative phrenic nerve stimulation was given according to individual training schedule. One case with total phrenic paralysis received bilateral phrenic nerve stimulation and became weaned from the ventilator 6 months later. The other case with partially active ventilatory function received unilateral phrenic nerve stimulation to compensate the ventilation. However, its final outcome still showed the necessity of a bilateral mode to achieve adequate ventilation irrespective of strenuous training for 2 years.

Early life sensory ability-ventilatory responses of thornback ray embryos (Raja clavata) to predator-type electric fields.

PubMed

Ball, Rachel Emma; Oliver, Matthew Kenneth; Gill, Andrew Bruce

2016-07-01

Predator avoidance is fundamental for survival and it can be particularly challenging for prey animals if physical movement away from a predatory threat is restricted. Many sharks and rays begin life within an egg capsule that is attached to the sea bed. The vulnerability of this sedentary life stage is exacerbated in skates (Rajidae) as the compulsory ventilatory activity of embryos makes them conspicuous to potential predators. Embryos can reduce this risk by mediating ventilatory activity if they detect the presence of a predator using an acute electrosense. To determine how early in embryonic life predator elicited behavioral responses can occur, the reactions of three different age groups (1/3 developed, 2/3 developed, and near hatching) of embryonic thornback rays Raja clavata were tested using predator-type electric field stimuli. Egg capsules were exposed to continuous or intermittent stimuli in order to assess varying predator-type encounter scenarios on the ventilatory behavior of different developmental stages. All embryos reacted with a "freeze response" following initial electric field (E-field) exposure, ceasing ventilatory behavior in response to predator presence, demonstrating electroreceptive functionality for the first time at the earliest possible stage in ontogeny. This ability coincided with the onset of egg ventilatory behavior and may represent an effective means to enhance survival. A continuous application of stimuli over time revealed that embryos can adapt their behavior and resume normal activity, whereas when presented intermittently, the E-field resulted in a significant reduction in overall ventilatory activity across all ages. Recovery from stimuli was significantly quicker in older embryos, potentially indicative of the trade-off between avoiding predation and adequate respiration. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 721-729, 2016. © 2015 Wiley Periodicals, Inc.

Alternating versus synchronous ventilation of left and right lungs in piglets.

PubMed

Versprille, A; Hrachovina, V; Jansen, J R

1995-12-01

We tested whether alternating ventilation (AV) of each lung (i.e. with a phase difference of half a ventilatory cycle) would decrease central venous pressure and so increase cardiac output when compared with simultaneous ventilation (SV) of both lungs. If, during AV, the inflated lung expands partly via compression of the opposite lung, mean lung volume will be smaller during AV than SV. As a consequence, mean intrathoracic pressure (as cited in the literature), and therefore, central venous pressure will be smaller. The experiments were performed in seven anaesthetized and paralyzed piglets using a double-piston ventilator. Minute ventilation was the same during AV and SV. Starting at SV, we alternated three times between AV and SV for periods of 10 min. During AV, central venous pressure was decreased by 0.7 mmHg and cardiac output was increased by 10 +/- 4.4% (mean, +/-SD) compared with SV. AV also resulted in increased arterial pressure. During one-sided inflation with closed outlet of the opposite lung, a pressure rise occurred in the opposite lung, indicating compression. The higher cardiac output during AV than SV can be explained by the fact that central venous pressure is lower during AV. This lower central venous pressure is very probably due to the lower mean intrathoracic pressure caused by compression of the opposite lung during unilateral inflation.

Phase I/II Trial of Adeno-Associated Virus–Mediated Alpha-Glucosidase Gene Therapy to the Diaphragm for Chronic Respiratory Failure in Pompe Disease: Initial Safety and Ventilatory Outcomes

PubMed Central

Smith, Barbara K.; Collins, Shelley W.; Conlon, Thomas J.; Mah, Cathryn S.; Lawson, Lee Ann; Martin, Anatole D.; Fuller, David D.; Cleaver, Brian D.; Clément, Nathalie; Phillips, Dawn; Islam, Saleem; Dobjia, Nicole

2013-01-01

Abstract Pompe disease is an inherited neuromuscular disease caused by deficiency of lysosomal acid alpha-glucosidase (GAA) leading to glycogen accumulation in muscle and motoneurons. Cardiopulmonary failure in infancy leads to early mortality, and GAA enzyme replacement therapy (ERT) results in improved survival, reduction of cardiac hypertrophy, and developmental gains. However, many children have progressive ventilatory insufficiency and need additional support. Preclinical work shows that gene transfer restores phrenic neural activity and corrects ventilatory deficits. Here we present 180-day safety and ventilatory outcomes for five ventilator-dependent children in a phase I/II clinical trial of AAV-mediated GAA gene therapy (rAAV1-hGAA) following intradiaphragmatic delivery. We assessed whether rAAV1-hGAA results in acceptable safety outcomes and detectable functional changes, using general safety measures, immunological studies, and pulmonary functional testing. All subjects required chronic, full-time mechanical ventilation because of respiratory failure that was unresponsive to both ERT and preoperative muscle-conditioning exercises. After receiving a dose of either 1×1012 vg (n=3) or 5×1012 vg (n=2) of rAAV1-hGAA, the subjects' unassisted tidal volume was significantly larger (median [interquartile range] 28.8% increase [15.2–35.2], p<0.05). Further, most patients tolerated appreciably longer periods of unassisted breathing (425% increase [103–851], p=0.08). Gene transfer did not improve maximal inspiratory pressure. Expected levels of circulating antibodies and no T-cell-mediated immune responses to the vector (capsids) were observed. One subject demonstrated a slight increase in anti-GAA antibody that was not considered clinically significant. These results indicate that rAAV1-hGAA was safe and may lead to modest improvements in volitional ventilatory performance measures. Evaluation of the next five patients will determine whether earlier intervention can further enhance the functional benefit. PMID:23570273

Soluble erythropoietin receptor is present in the mouse brain and is required for the ventilatory acclimatization to hypoxia

PubMed Central

Soliz, Jorge; Gassmann, Max; Joseph, Vincent

2007-01-01

While erythropoietin (Epo) and its receptor (EpoR) have been widely investigated in brain, the expression and function of the soluble Epo receptor (sEpoR) remain unknown. Here we demonstrate that sEpoR, a negative regulator of Epo's binding to the EpoR, is present in the mouse brain and is down-regulated by 62% after exposure to normobaric chronic hypoxia (10% O2 for 3 days). Furthermore, while normoxic minute ventilation increased by 58% in control mice following hypoxic acclimatization, sEpoR infusion in brain during the hypoxic challenge efficiently reduced brain Epo concentration and abolished the ventilatory acclimatization to hypoxia (VAH). These observations imply that hypoxic downregulation of sEpoR is required for adequate ventilatory acclimatization to hypoxia, thereby underlying the function of Epo as a key factor regulating oxygen delivery not only by its classical activity on red blood cell production, but also by regulating ventilation. PMID:17584830

Analysis of the respiratory component of heart rate variability in the Cururu toad Rhinella schneideri.

PubMed

Zena, Lucas A; Leite, Cléo A C; Longhini, Leonardo S; Dias, Daniel P M; da Silva, Glauber S F; Hartzler, Lynn K; Gargaglioni, Luciane H; Bícego, Kênia C

2017-11-23

Beat-to-beat variation in heart rate (f H ) has been used as a tool for elucidating the balance between sympathetic and parasympathetic modulation of the heart. A portion of the temporal changes in f H is evidenced by a respiratory influence (cardiorespiratory interaction) on heart rate variability (HRV) with heartbeats increasing and decreasing within a respiratory cycle. Nevertheless, little is known about respiratory effects on HRV in lower vertebrates. By using frequency domain analysis, we provide the first evidence of a ventilatory component in HRV similar to mammalian respiratory sinus arrhythmia in an amphibian, the toad Rhinella schneideri. Increases in the heartbeats arose synchronously with each lung inflation cycle, an intermittent breathing pattern comprised of a series of successive lung inflations. A well-marked peak in the HRV signal matching lung inflation cycle was verified in toads whenever lung inflation cycles exhibit a regular rhythm. The cardiac beat-to-beat variation evoked at the moment of lung inflation accounts for both vagal and sympathetic influences. This cardiorespiratory interaction may arise from interactions between central and peripheral feedback mechanisms governing cardiorespiratory control and may underlie important cardiorespiratory adjustments for gas exchange improvement especially under extreme conditions like low oxygen availability.

Analysis of discrete and continuous distributions of ventilatory time constants from dynamic computed tomography

NASA Astrophysics Data System (ADS)

Doebrich, Marcus; Markstaller, Klaus; Karmrodt, Jens; Kauczor, Hans-Ulrich; Eberle, Balthasar; Weiler, Norbert; Thelen, Manfred; Schreiber, Wolfgang G.

2005-04-01

In this study, an algorithm was developed to measure the distribution of pulmonary time constants (TCs) from dynamic computed tomography (CT) data sets during a sudden airway pressure step up. Simulations with synthetic data were performed to test the methodology as well as the influence of experimental noise. Furthermore the algorithm was applied to in vivo data. In five pigs sudden changes in airway pressure were imposed during dynamic CT acquisition in healthy lungs and in a saline lavage ARDS model. The fractional gas content in the imaged slice (FGC) was calculated by density measurements for each CT image. Temporal variations of the FGC were analysed assuming a model with a continuous distribution of exponentially decaying time constants. The simulations proved the feasibility of the method. The influence of experimental noise could be well evaluated. Analysis of the in vivo data showed that in healthy lungs ventilation processes can be more likely characterized by discrete TCs whereas in ARDS lungs continuous distributions of TCs are observed. The temporal behaviour of lung inflation and deflation can be characterized objectively using the described new methodology. This study indicates that continuous distributions of TCs reflect lung ventilation mechanics more accurately compared to discrete TCs.

Pediatric Acute Lung Injury Epidemiology and Natural History study: Incidence and outcome of the acute respiratory distress syndrome in children.

PubMed

López-Fernández, Yolanda; Azagra, Amelia Martínez-de; de la Oliva, Pedro; Modesto, Vicent; Sánchez, Juan I; Parrilla, Julio; Arroyo, María José; Reyes, Susana Beatriz; Pons-Ódena, Martí; López-Herce, Jesús; Fernández, Rosa Lidia; Kacmarek, Robert M; Villar, Jesús

2012-12-01

The incidence and outcome of the acute respiratory distress syndrome in children are not well-known, especially under current ventilatory practices. The goal of this study was to determine the incidence, etiology, and outcome of acute respiratory distress syndrome in the pediatric population in the setting of lung protective ventilation. A 1-yr, prospective, multicenter, observational study in 12 geographical areas of Spain (serving a population of 3.77 million ≤ 15 yrs of age) covered by 21 pediatric intensive care units. All consecutive pediatric patients receiving invasive mechanical ventilation and meeting American-European Consensus Criteria for acute respiratory distress syndrome. None. Data on ventilatory management, gas exchange, hemodynamics, and organ dysfunction were collected. A total of 146 mechanically ventilated patients fulfilled the acute respiratory distress syndrome definition, representing a incidence of 3.9/100,000 population ≤ 15 yrs of age/yr. Pneumonia and sepsis were the most common causes of acute respiratory distress syndrome. At the time of meeting acute respiratory distress syndrome criteria, mean PaO2/FIO2 was 99 mm Hg ± 41 mm Hg, mean tidal volume was 7.6 mL/kg ± 1.8 mL/kg predicted body weight, mean plateau pressure was 27 cm H2O ± 6 cm H2O, and mean positive end-expiratory pressure was 8.9 cm ± 2.9 cm H2O. Overall pediatric intensive care unit and hospital mortality were 26% (95% confidence interval 19.6-33.7) and 27.4% (95% confidence interval 20.8-35.1), respectively. At 24 hrs, after the assessment of oxygenation under standard ventilatory settings, 118 (80.8%) patients continued to meet acute respiratory distress syndrome criteria (PaO2/FIO2 104 mm Hg ± 36 mm Hg; pediatric intensive care units mortality 30.5%), whereas 28 patients (19.2%) had a PaO2/FIO2 >200 mm Hg (pediatric intensive care units mortality 7.1%) (p = .014). This is the largest study to estimate prospectively the pediatric population-based acute respiratory distress syndrome incidence and the first incidence study performed during the routine application of lung protective ventilation in children. Our findings support a lower acute respiratory distress syndrome incidence and mortality than those reported for adults. PaO2/FIO2 ratios at acute respiratory distress syndrome onset and at 24 hrs after onset were helpful in defining groups at greater risk of dying (clinical trials registered with http://www.clinicaltrials.gov; NCT 01142544).

Lung volumes in giraffes, Giraffa camelopardalis.

PubMed

Mitchell, G; Skinner, J D

2011-01-01

We have measured lung mass and trachea dimensions in 46 giraffes of both genders ranging in body mass from 147 kg to 1441 kg, calculated static and dynamic lung volumes, and developed allometric equations that relate changes in them to growth. We found that relative lung mass is 0.6±0.2% of body mass which is significantly less than it is in other mammals (1.1±0.1%). Total lung volume is significantly smaller (46.2±5.9 mL kg⁻¹) than in similar sized mammals (75.0±2.1 mL kg⁻¹). The lung volume:body mass ratio decreases during growth rather than increase as it does in other mammals. Tracheal diameter is significantly narrower than in similar sized mammals but dead space volume (2.9±0.5 mL kg⁻¹) is larger than in similar sized mammals (2.4±0.1 mL kg⁻¹). Our calculations suggest that tidal volume (10.5±0.2 mL kg⁻¹) is increased compared to that in other mammals(10.0±0.2 mL kg⁻¹) so that the dead space:tidal volume ratio is the same as in other mammals. Calculated Functional Residual Capacity is smaller than predicted (53.4±3.5 vs 33.7±0.6 mL kg⁻¹) as is Expiratory Reserve Volume (47.4±2.6 vs 27.2±1.0 mL kg⁻¹, but Residual Volume (6.0±0.4 mL kg⁻¹) is the same as in other similar sized mammals (6.0±0.9 mL kg⁻¹. Our calculations suggest that Inspiratory Reserve Volume is significantly reduced in size (11.6±1.6 vs 3.8±2.4 mL kg⁻¹), and, if so, the capacity to increase tidal volume is limited. Calculated dynamic lung volumes were the same as in similar sized mammals. We have concluded that giraffe morphology has resulted in lung volumes that are significantly different to that of similar sized mammals, but these changes do not compromise ventilatory capacity. Copyright © 2010 Elsevier Inc. All rights reserved.

Effect of Aerobic Exercise Training on Ventilatory Efficiency and Respiratory Drive in Obese Subjects.

PubMed

Chlif, Mehdi; Chaouachi, Anis; Ahmaidi, Said

2017-07-01

Obese patients show a decline in exercise capacity and diverse degrees of dyspnea in association with mechanical abnormalities, increased ventilatory requirements secondary to the increased metabolic load, and a greater work of breathing. Consequently, obese patients may be particularly predisposed to the development of respiratory muscle fatigue during exercise. The aim of this study was to assess inspiratory muscle performance during incremental exercise in 19 obese male subjects (body mass index 41 ± 6 kg/m 2 ) after aerobic exercise training using the noninvasive, inspiratory muscle tension-time index (T T0.1 ). Measurements performed included anthropometric parameters, lung function assessed by spirometry, rate of perceived breathlessness with the modified Borg dyspnea scale (0-10), breathing pattern, maximal exercise capacity, and inspiratory muscle performance with a breath-by-breath automated exercise metabolic system during an incremental exercise test. T T0.1 was calculated using the equation, T T0.1 = P 0.1 /P Imax × T I /T tot (where P 0.1 represents mouth occlusion pressure, P Imax is maximal inspiratory pressure, and T I /T tot is the duty cycle). At rest, there was no statistically significant difference for spirometric parameters and cardiorespiratory parameters between pre- and post-training. At maximal exercise, the minute ventilation, the rate of exchange ratio, the rate of perceived breathlessness, and the respiratory muscle performance parameters were not significantly different pre- and post-training; in contrast, tidal volume ( P = .037, effect size = 1.51), breathing frequency ( P = .049, effect size = 0.97), power output ( P = .048, effect size = 0.79), peak oxygen uptake ( P = .02, effect size = 0.92) were significantly higher after training. At comparable work load, training induces lower minute ventilation, mouth occlusion pressure, ratio of occlusion pressure to maximal inspiratory pressure, T T0.1 , and rate of perceived breathlessness. Aerobic exercise at ventilatory threshold can induce significant improvement in respiratory muscle strength, maximal exercise capacity, and inspiratory muscle performance and decreased dyspnea perception in obese subjects. Copyright © 2017 by Daedalus Enterprises.

PERIODIC AIR-BREATHING BEHAVIOUR IN A PRIMITIVE FISH REVEALED BY SPECTRAL ANALYSIS

PubMed

Hedrick; Katz; Jones

1994-12-01

The ventilatory patterns of air-breathing fish are commonly described as 'arrhythmic' or 'irregular' because the variable periods of breath-holding are punctuated by seemingly unpredictable air-breathing events (see Shelton et al. 1986). This apparent arrhythmicity contrasts with the perceived periodism or regularity in the gill ventilation patterns of some fish and with lung ventilation in birds and mammals. In this sense, periodism refers to behaviour that occurs with a definite, recurring interval (Bendat and Piersol, 1986). The characterisation of aerial ventilation patterns in fish as 'aperiodic' has been generally accepted on the basis of qualitative examination and it remains to be validated with rigorous testing. The bowfin, Amia calva (L.), is a primitive air-breathing fish that makes intermittent excursions to the air­water interface to gulp air, which is transferred to its well-vascularized gas bladder. Its phylogenetic position as the only extant member of the sister lineage of modern teleosts affords a unique opportunity to examine the evolution of aerial ventilation and provides a model for the examination of ventilatory patterns in primitive fishes. To establish whether Amia calva exhibit a particular pattern of air-breathing, we examined time series records of aerial ventilations from undisturbed fish over long periods (8 h). These records were the same as those used to calculate average ventilation intervals under a variety of experimental conditions (Hedrick and Jones, 1993). Their study also reported the occurrence of two distinct breath types. Type I breaths were characterised by an exhalation followed by an inhalation, whereas type II breaths were characterised by inhalation only. It was also hypothesized that the type I breaths were employed to meet oxygen demands, whereas the type II breaths were used to regulate gas bladder volume. However, they did not investigate the potential presence of a periodic ventilatory pattern. We now report the results of just such an analysis of ventilatory pattern that demonstrates a clear periodism to air-breathing in a primitive fish.

Effects of fenoterol on ventilatory response to hypercapnia and hypoxia in patients with chronic obstructive pulmonary disease

PubMed Central

Suzuki, S.; Watanuki, Y.; Yoshiike, Y.; Okubo, T.

1997-01-01

BACKGROUND: It has previously been shown that fenoterol, a beta 2 adrenergic agonist, increases the ventilatory response to hypoxia (HVR) and hypercapnia (HCVR) in normal subjects. The effects of beta 2 adrenergic agonists on chemoreceptors in patients with chronic obstructive pulmonary disease (COPD) remain controversial. This study was designed to examine whether fenoterol increases the HVR and HCVR in patients with COPD. METHODS: The HCVR was tested in 20 patients using a rebreathing method and the HVR was examined using a progressive isocapnic hypoxic method. The HCVR and HVR were assessed by calculating the slopes of plots of occlusion pressure (P0.1) and ventilation (VE) against end tidal carbon dioxide pressure (PETCO2) and arterial oxygen saturation (SaO2), respectively. Spirometric values, lung volumes, and respiratory muscle strength were also measured. The HCVR and HVR were examined after the oral administration of fenoterol (15 mg/day) or placebo for seven days. RESULTS: Fenoterol treatment increased the forced expiratory volume in one second (FEV1) and inspiratory muscle strength. In the HCVR the slope of P0.1 versus PETCO2 was increased by fenoterol from 0.35 (0.23) to 0.43 (0.24) (p < 0.01). Moreover, the P0.1 at PETCO2 of 8 kPa was higher on fenoterol than on placebo (p < 0.05) and the VE was also greater (p < 0.01). In the HVR fenoterol treatment increased the P0.1 at 80% SaO2 from 0.90 (0.72) to 0.97 (0.55) kPa (p < 0.05) while the slopes of the response of P0.1 and VE were not changed. CONCLUSIONS: Fenoterol increases the ventilatory response to hypercapnia in patients with COPD, presumably by stimulation of the central chemoreceptor. The hypoxic ventilatory response is only slightly affected by fenoterol. 


 PMID:9059471

Insights into Ventilatory Inhomogeneity from Respiratory Measurements on Spacelab Mission D-2

NASA Technical Reports Server (NTRS)

Paiva, Manuel; Verbanck, Sylvia; Linnarsson, Dag; Prisk, Kim; West, John B.

1996-01-01

The relative contributions of inter-regional and intra-regional ventilation inhomogeneities of Spacelab astronauts are studied. The classical theory of ventilation distribution in the lung is that the top-to-bottom (inter-regional) ventilation inhomogeneities are primarily gravity dependent, whereas the peripheral (intra-regional) ventilation distribution is gravity independent. Argon rebreathing tests showed that gravity independent specific ventilation (ventilation per unit volume) inhomogeneities are at least as large as gravity dependent ones. Single breath tests with helium and sulfur hexafluoride showed the different sensitivity of these gases to microgravity.

Single-Site Cannulation Venovenous Extracorporeal CO2 Removal as Bridge to Lung Volume Reduction Surgery in End-Stage Lung Emphysema.

PubMed

Redwan, Bassam; Ziegeler, Stephan; Semik, Michael; Fichter, Joachim; Dickgreber, Nicolas; Vieth, Volker; Ernst, Erik Christian; Fischer, Stefan

Lung volume reduction surgery (LVRS) is an important treatment option for end-stage lung emphysema in carefully selected patients. Here, we first describe the application of low-flow venovenous extracorporeal CO2 removal (LFVV-ECCO2R) as bridge to LVRS in patients with end-stage lung emphysema experiencing severe hypercapnia caused by acute failure of the breathing pump. Between March and October 2015, n = 4 patients received single-site LFVV-ECCO2R as bridge to LVRS. Indication for extracorporeal lung support was severe hypercapnia with respiratory acidosis and acute breathing pump failure. Two patients required continuous mechanical ventilation over a temporary tracheostomy and were bed ridden. The other two patients were nearly immobile because of severe dyspnea at rest. Length of preoperative ECCO2R was 14 (1-42) days. All patients underwent unilateral LVRS. Anatomical resection of the right (n = 3) or left (n = 1) upper lobe was performed. Postoperatively, both patients with previous mechanical ventilatory support were successfully weaned. ECCO2R in patients with end-stage lung emphysema experiencing severe hypercapnia caused by acute breathing pump failure is a safe and effective bridging tool to LVRS. In such patients, radical surgery leads to a significant improvement of the performance status and furthermore facilitates respiratory weaning from mechanical ventilation.

The impact of obesity on specific airway resistance and conductance among schoolchildren.

PubMed

Parraguez Arévalo, Andrea; Rojas Navarro, Francisco; Ruz Céspedes, Macarena; Medina González, Paul; Escobar Cabello, Máximo; Muñoz Cofré, Rodrigo

2018-04-01

Child and adolescent obesity is an epidemiological problem in developing countries. Its prevalence among preschoolers and schoolchildren is over 30%. It has been associated with a wide range of health complications, including rapid loss of lung function leading to changes in physiology and ventilatory mechanics. The objective of this study was to analyze the association between obesity and the increase in specific airway resistance (sRaw) in a sample of obese children and adolescents from the district of Talca. In a sample of 36 subjects with an average age of 9.38 ± 1.99 years, divided into 2 groups (normal weight and obese), the tricipital, subscapular, and abdominal skinfolds and lung volumes were measured. For the statistical analysis, data normality was determined and then the Student's t test or the Mann-Whitney U test and Pearson's or Spearman's correlations were used, as applicable. A value of p < 0.05 was considered statistically significant. When comparing normal weight and obese subjects, a significant increase in sRaw and a significant reduction in specific airway conductance (sGaw) were observed in obese subjects. In addition, an adequate and significant correlation was observed between sRaw and fat percentage. Obese subjects showed an increased sRaw and a reduced sGaw. Sociedad Argentina de Pediatría.

The individual response to training and competition at altitude.

PubMed

Chapman, Robert F

2013-12-01

Performance in athletic activities that include a significant aerobic component at mild or moderate altitudes shows a large individual variation. Physiologically, a large portion of the negative effect of altitude on exercise performance can be traced to limitations of oxygen diffusion, either at the level of the alveoli or the muscle microvasculature. In the lung, the ability to maintain arterial oxyhaemoglobin saturation (SaO₂) appears to be a primary factor, ultimately influencing oxygen delivery to the periphery. SaO₂ in hypoxia can be defended by increasing ventilatory drive; however, during heavy exercise, many athletes demonstrate limitations to expiratory flow and are unable to increase ventilation in hypoxia. Additionally, increasing ventilatory work in hypoxia may actually be negative for performance, if dyspnoea increases or muscle blood flow is reduced secondary to an increased sympathetic outflow (eg, the muscle metaboreflex response). Taken together, some athletes are clearly more negatively affected during exercise in hypoxia than other athletes. With careful screening, it may be possible to develop a protocol for determining which athletes may be the most negatively affected during competition and/or training at altitude.

Respiration and the generation of rhythmic outputs in insects.

PubMed

Kammer, A E

1976-07-01

In insects gas exchange may be: 1) entirely passive, when metabolic rate is low; 2) enhanced automatically by muscle contractions that produce movements, e.g., wing movements in flight; or 3) produced by ventilatory movements, particularly of the abdomen. In terrestrial insects such as locusts and cockroaches ventilatory movements are governed by a dominant oscillator in the metathoracic or anterior abdominal ganglion. The dominant oscillator overrides local oscillators in the abdominal ganglia and thus sets the rhythm for the entire abdomen, and it also controls spiracle opening and closing in several thoracic and abdominal segments. This ventilatory control mechanism appears to be different from that generating metachronal rhythms such as occur in the ventilatory and locomotory movements of aquatic arthropods. There are now several examples of rhythms, both ventilatory and locomotory, that can be generated by the central nervous system in the absence of phasic sensory feedback, but the mechanism of rhythm production is not known. Studies of ganglionic output suggest that neuronal oscillators can produce a range of frequencies and that some oscillators may be employed in more than one function or behavior. The mechanisms by which central oscillators are coupled to the output motorneurons are also not known; large phase changes suggest that in some cases different coupling interneurons are active. Intracellular recordings from identified neurons have begun to clarify the important roles of interneurons in the production of motor patterns.

When obesity and chronic obstructive pulmonary disease collide. Physiological and clinical consequences.

PubMed

O'Donnell, Denis E; Ciavaglia, Casey E; Neder, J Alberto

2014-05-01

In many parts of the world, the prevalence of both chronic obstructive pulmonary disease (COPD) and obesity is increasing at an alarming rate. Such patients tend to have greater respiratory symptoms, more severe restriction of daily activities, poorer health-related quality of life, and greater health care use than their nonobese counterparts. Physiologically, increasing weight gain is associated with lung volume reduction effects in both health and disease, and this should be considered when interpreting common pulmonary function tests where lung volume is the denominator, such as FEV1/FVC and the ratio of diffusing capacity of carbon monoxide to alveolar volume, or indeed when evaluating the physiological consequences of emphysema in obese individuals. Contrary to expectation, the presence of mild to moderate obesity in COPD appears to have little deleterious effect on respiratory mechanics and muscle function, exertional dyspnea, and peak symptom-limited oxygen uptake during cardiopulmonary exercise testing. Thus, in evaluating obese patients with COPD reporting activity restriction, additional nonpulmonary factors, such as increased metabolic loading, cardiocirculatory impairment, and musculoskeletal abnormalities, should be considered. Care should be taken to recognize the presence of obstructive sleep apnea in obese patients with COPD, as effective treatment of the former condition likely conveys an important survival advantage. Finally, morbid obesity in COPD presents significant challenges to effective management, given the combined effects of erosion of the ventilatory reserve and serious metabolic and cardiovascular comorbidities that collectively predispose to an increased risk of death from respiratory failure.

Acute native lung hyperinflation is not associated with poor outcomes after single lung transplant for emphysema.

PubMed

Weill, D; Torres, F; Hodges, T N; Olmos, J J; Zamora, M R

1999-11-01

Single-lung transplantation for emphysema may be complicated by acute native lung hyperinflation (ANLH) with hemodynamic and ventilatory compromise. Some groups advocate the routine use of independent lung ventilation, double-lung transplant, or right-lung transplant with or without contralateral lung volume reduction surgery in high-risk patients. The goal of this study was to determine the incidence of ANLH and identify its potential predictors. We reviewed 51 consecutive single-lung transplants for emphysema. Symptomatic ANLH was defined as mediastinal shift and diaphragmatic flattening on chest x-ray with hemodynamic or respiratory failure requiring cardiopressor agents or independent lung ventilation. Preoperative and postoperative physiologic and hemodynamic data were analyzed from both recipients and donors. Sixteen patients developed radiographic ANLH; 8 were symptomatic, 2 severely so. We could not identify high-risk patients before transplant by pulmonary function tests, predicted donor total lung capacity (TLC)/actual recipient TLC ratio, pulmonary artery pressures, or the side transplanted. There was a trend toward an increased incidence of symptomatic ANLH in patients with bullous emphysema on chest computed tomography, but this was accounted for primarily by patients with alpha1-antitrypsin deficiency (4/13 vs 4/38 with chronic obstructive pulmonary disease, P = 0.10). No patient required cardiopulmonary bypass or inhaled nitric oxide intraoperatively. Patients with acute native lung hyperinflation did not have increased reperfusion edema as measured by chest x-ray score or PaO2/F(I)O2 ratio. Compared to patients without ANLH, symptomatic patients had longer ventilator times (64.9+/-14.6 hours vs 40.4+/-3.9, P = 0.02, ANOVA) and longer lengths of stay (19.3+/-2.1 days vs 13.7+/-1.3, P = 0.07), but 30-day survival was 100%. Two symptomatic patients required independent lung ventilation or inhaled nitric oxide; the others were managed with decreased minute ventilation, early extubation, and cardiopressor agents. No patient required early lung volume reduction surgery or retransplantation. Acute native lung hyperinflation had no effect on FEV1 or 6-minute walk results at 1 year; survival at 1, 2, or 3 years; or the rate of acute rejection, infection, or bronchiolitis obliterans syndrome greater than grade 2. Acute native lung hyperinflation is common radiographically but is rarely clinically severe. Although there was a trend toward an increase in symptomatic ANLH in patients with bullous emphysema, a high-risk group could not be identified preoperatively. Our results do not support the routine use of bilateral lung transplant, the exclusive use of right single-lung transplant, simultaneous lung volume reduction surgery, or independent lung ventilation for patients with emphysema. Management strategies should be employed that limit overdistension of the native lung and lead to early extubation.

Early stabilizing alveolar ventilation prevents acute respiratory distress syndrome: a novel timing-based ventilatory intervention to avert lung injury.

PubMed

Roy, Shreyas; Sadowitz, Benjamin; Andrews, Penny; Gatto, Louis A; Marx, William; Ge, Lin; Wang, Guirong; Lin, Xin; Dean, David A; Kuhn, Michael; Ghosh, Auyon; Satalin, Joshua; Snyder, Kathy; Vodovotz, Yoram; Nieman, Gary; Habashi, Nader

2012-08-01

Established acute respiratory distress syndrome (ARDS) is often refractory to treatment. Clinical trials have demonstrated modest treatment effects, and mortality remains high. Ventilator strategies must be developed to prevent ARDS. Early ventilatory intervention will block progression to ARDS if the ventilator mode (1) maintains alveolar stability and (2) reduces pulmonary edema formation. Yorkshire pigs (38-45 kg) were anesthetized and subjected to a "two-hit" ischemia-reperfusion and peritoneal sepsis. After injury, animals were randomized into two groups: early preventative ventilation (airway pressure release ventilation [APRV]) versus nonpreventative ventilation (NPV) and followed for 48 hours. All animals received anesthesia, antibiotics, and fluid or vasopressor therapy as per the Surviving Sepsis Campaign. Titrated for optimal alveolar stability were the following ventilation parameters: (1) NPV group--tidal volume, 10 mL/kg + positive end-expiratory pressure - 5 cm/H2O volume-cycled mode; (2) APRV group--tidal volume, 10 to 15 mL/kg; high pressure, low pressure, time duration of inspiration (Thigh), and time duration of release phase (Tlow). Physiological data and plasma were collected throughout the 48-hour study period, followed by BAL and necropsy. APRV prevented the development of ARDS (p < 0.001 vs. NPV) by PaO₂/FIO₂ ratio. Quantitative histological scoring showed that APRV prevented lung tissue injury (p < 0.001 vs. NPV). Bronchoalveolar lavage fluid showed that APRV lowered total protein and interleukin 6 while preserving surfactant proteins A and B (p < 0.05 vs. NPV). APRV significantly lowered lung water (p < 0.001 vs. NPV). Plasma interleukin 6 concentrations were similar between groups. Early preventative mechanical ventilation with APRV blocked ARDS development, preserved surfactant proteins, and reduced pulmonary inflammation and edema despite systemic inflammation similar to NPV. These data suggest that early preventative ventilation strategies stabilizing alveoli and reducing pulmonary edema can attenuate ARDS after ischemia-reperfusion and sepsis.

Mechanical ventilation in acute respiratory distress syndrome: The open lung revisited.

PubMed

Amado-Rodríguez, L; Del Busto, C; García-Prieto, E; Albaiceta, G M

2017-12-01

Acute respiratory distress syndrome (ARDS) is still related to high mortality and morbidity rates. Most patients with ARDS will require ventilatory support. This treatment has a direct impact upon patient outcome and is associated to major side effects. In this regard, ventilator-associated lung injury (VALI) is the main concern when this technique is used. The ultimate mechanisms of VALI and its management are under constant evolution. The present review describes the classical mechanisms of VALI and how they have evolved with recent findings from physiopathological and clinical studies, with the aim of analyzing the clinical implications derived from them. Lastly, a series of knowledge-based recommendations are proposed that can be helpful for the ventilator assisted management of ARDS at the patient bedside. Copyright © 2017 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

Individualized positive end-expiratory pressure application in patients with acute respiratory distress syndrome.

PubMed

Pintado, M C; de Pablo, R

2014-11-01

Current treatment of acute respiratory distress syndrome is based on ventilatory support with a lung protective strategy, avoiding the development of iatrogenic injury, including ventilator-induced lung injury. One of the mechanisms underlying such injury is atelectrauma, and positive end-expiratory pressure (PEEP) is advocated in order to avoid it. The indicated PEEP level has not been defined, and in many cases is based on the patient oxygen requirements for maintaining adequate oxygenation. However, this strategy does not consider the mechanics of the respiratory system, which varies in each patient and depends on many factors-including particularly the duration of acute respiratory distress syndrome. A review is therefore made of the different methods for adjusting PEEP, focusing on the benefits of individualized application. Copyright © 2013 Elsevier España, S.L.U. and SEMICYUC. All rights reserved.

Postural lung recruitment assessed by lung ultrasound in mechanically ventilated children.

PubMed

Tusman, Gerardo; Acosta, Cecilia M; Böhm, Stephan H; Waldmann, Andreas D; Ferrando, Carlos; Marquez, Manuel Perez; Sipmann, Fernando Suarez

2017-10-13

Atelectasis is a common finding in mechanically ventilated children with healthy lungs. This lung collapse cannot be overcome using standard levels of positive end-expiratory pressure (PEEP) and thus for only individualized lung recruitment maneuvers lead to satisfactory therapeutic results. In this short communication, we demonstrate by lung ultrasound images (LUS) the effect of a postural recruitment maneuver (P-RM, i.e., a ventilatory strategy aimed at reaerating atelectasis by changing body position under constant ventilation). Data was collected in the operating room of the Hospital Privado de Comunidad, Mar del Plata, Argentina. Three anesthetized children undergoing mechanical ventilation at constant settings were sequentially subjected to the following two maneuvers: (1) PEEP trial in the supine position PEEP was increased to 10 cmH 2 O for 3 min and then decreased to back to baseline. (2) P-RM patient position was changed from supine to the left and then to the right lateral position for 90 s each before returning to supine. The total P-RM procedure took approximately 3 min. LUS in the supine position showed similar atelectasis before and after the PEEP trial. Contrarily, atelectasis disappeared in the non-dependent lung when patients were placed in the lateral positions. Both lungs remained atelectasis free even after returning to the supine position. We provide LUS images that illustrate the concept and effects of postural recruitment in children. This maneuver has the advantage of achieving recruitment effects without the need to elevate airways pressures.

Neural control of ventilation prevents both over-distension and de-recruitment of experimentally injured lungs.

PubMed

Brander, Lukas; Moerer, Onnen; Hedenstierna, Göran; Beck, Jennifer; Takala, Jukka; Slutsky, Arthur S; Sinderby, Christer

2017-03-01

Endogenous pulmonary reflexes may protect the lungs during mechanical ventilation. We aimed to assess integration of continuous neurally adjusted ventilatory assist (cNAVA), delivering assist in proportion to diaphragm's electrical activity during inspiration and expiration, and Hering-Breuer inflation and deflation reflexes on lung recruitment, distension, and aeration before and after acute lung injury (ALI). In 7 anesthetised rabbits with bilateral pneumothoraces, we identified adequate cNAVA level (cNAVA AL ) at the plateau in peak ventilator pressure during titration procedures before (healthy lungs with endotracheal tube, [HL ETT ]) and after ALI (endotracheal tube [ALI ETT ] and during non-invasive ventilation [ALI NIV ]). Following titration, cNAVA AL was maintained for 5min. In 2 rabbits, procedures were repeated after vagotomy (ALI ETT+VAG ). In 3 rabbits delivery of assist was temporarily modulated to provide assist on inspiration only. Computed tomography was performed before intubation, before ALI, during cNAVA titration, and after maintenance at cNAVA AL . During ALI ETT and ALI NIV , normally aerated lung-regions doubled and poorly aerated lung-regions decreased to less than a third (p<0.05) compared to HL ETT ; no over-distension was observed. Tidal volumes were<5ml/kg throughout. Removing assist during expiration resulted in lung de-recruitment during ALI ETT , but not during ALI NIV . During ALI ETT+VAG the expiratory portion of EAdi disappeared, resulting in cyclic lung collapse and recruitment. When using cNAVA in ALI, vagally mediated reflexes regulated lung recruitment preventing both lung over-distension and atelectasis. During non-invasive cNAVA the upper airway muscles play a role in preventing atelectasis. Future studies should be performed to compare these findings with conventional lung-protective approaches. Copyright © 2016 Elsevier B.V. All rights reserved.

Clinical outcomes of patients requiring ventilatory support in Brazilian intensive care units: a multicenter, prospective, cohort study

PubMed Central

2013-01-01

Introduction Contemporary information on mechanical ventilation (MV) use in emerging countries is limited. Moreover, most epidemiological studies on ventilatory support were carried out before significant developments, such as lung protective ventilation or broader application of non-invasive ventilation (NIV). We aimed to evaluate the clinical characteristics, outcomes and risk factors for hospital mortality and failure of NIV in patients requiring ventilatory support in Brazilian intensive care units (ICU). Methods In a multicenter, prospective, cohort study, a total of 773 adult patients admitted to 45 ICUs over a two-month period requiring invasive ventilation or NIV for more than 24 hours were evaluated. Causes of ventilatory support, prior chronic health status and physiological data were assessed. Multivariate analysis was used to identifiy variables associated with hospital mortality and NIV failure. Results Invasive MV and NIV were used as initial ventilatory support in 622 (80%) and 151 (20%) patients. Failure with subsequent intubation occurred in 54% of NIV patients. The main reasons for ventilatory support were pneumonia (27%), neurologic disorders (19%) and non-pulmonary sepsis (12%). ICU and hospital mortality rates were 34% and 42%. Using the Berlin definition, acute respiratory distress syndrome (ARDS) was diagnosed in 31% of the patients with a hospital mortality of 52%. In the multivariate analysis, age (odds ratio (OR), 1.03; 95% confidence interval (CI), 1.01 to 1.03), comorbidities (OR, 2.30; 95% CI, 1.28 to 3.17), associated organ failures (OR, 1.12; 95% CI, 1.05 to 1.20), moderate (OR, 1.92; 95% CI, 1.10 to 3.35) to severe ARDS (OR, 2.12; 95% CI, 1.01 to 4.41), cumulative fluid balance over the first 72 h of ICU (OR, 2.44; 95% CI, 1.39 to 4.28), higher lactate (OR, 1.78; 95% CI, 1.27 to 2.50), invasive MV (OR, 2.67; 95% CI, 1.32 to 5.39) and NIV failure (OR, 3.95; 95% CI, 1.74 to 8.99) were independently associated with hospital mortality. The predictors of NIV failure were the severity of associated organ dysfunctions (OR, 1.20; 95% CI, 1.05 to 1.34), ARDS (OR, 2.31; 95% CI, 1.10 to 4.82) and positive fluid balance (OR, 2.09; 95% CI, 1.02 to 4.30). Conclusions Current mortality of ventilated patients in Brazil is elevated. Implementation of judicious fluid therapy and a watchful use and monitoring of NIV patients are potential targets to improve outcomes in this setting. Trial registration ClinicalTrials.gov NCT01268410. PMID:23557378

Symposium on allergic lung disease. I. The clinical picture of asthma.

PubMed

Rebuck, A S

1974-02-16

Life-threatening asthma may be judged to be present in patients who, in the presence of a low FEV(1) are too dyspneic to speak, have altered consciousness or unequivocal cyanosis. Other physical signs which indicate airway obstruction of grave severity are pulsus paradoxus, gross thoracic overinflation and electrocardiographic evidence of pulmonary hypertension. A rise in the arterial CO(2) tension, the presence of pneumothorax or pneumomediastinum, and an FEV(1) less than 1 litre and vital capacity less than 0.5 litre, failing to increase immediately after inhalation of a bronchodilator, are also features which demand urgent and intensive therapy.Corticosteroids in large doses should be administered whenever a life-threatening situation is recognized. Systemic steroids should be stopped only when the danger phase, as indicated by the criteria given above, has been reversed. At all stages of therapy regular inhalations of a sympathomimetic bronchodilator should be maintained. Oral steroid therapy should be continued until maximum ventilatory function has been attained; only then should dose reduction be attempted.

The 2014 ESPEN Arvid Wretlind Lecture: Metabolism & nutrition: Shifting paradigms in COPD management.

PubMed

Schols, Annemie M W J

2015-12-01

COPD is a chronic disease of the lungs, but heterogeneous with respect to clinical manifestations and disease progression. This has consequences for health risk assessment, stratification and management. Heterogeneity can be driven by pulmonary events but also by systemic consequences (e.g. cachexia and muscle weakness) and co-morbidity (e.g. osteoporosis, diabetes and cardiovascular disease). This paper shows how a metabolic perspective on COPD has contributed significantly to understanding clinical heterogeneity and the need for a paradigm shift from reactive medicine towards predictive, preventive, personalized and participatory medicine. These insights have also lead to a paradigm shift in nutritional therapy for COPD from initial ignorance or focusing on putative adverse effects of carbohydrate overload on the ventilatory system to beneficial effects of nutritional intervention on body composition and physical functioning as integral part of disease management. The wider implications beyond COPD as disease have been as clinical model for translational cachexia research. Copyright © 2015 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Pathogenesis of hyperinflation in chronic obstructive pulmonary disease

PubMed Central

Gagnon, Philippe; Guenette, Jordan A; Langer, Daniel; Laviolette, Louis; Mainguy, Vincent; Maltais, François; Ribeiro, Fernanda; Saey, Didier

2014-01-01

Chronic obstructive pulmonary disease (COPD) is a preventable and treatable lung disease characterized by airflow limitation that is not fully reversible. In a significant proportion of patients with COPD, reduced lung elastic recoil combined with expiratory flow limitation leads to lung hyperinflation during the course of the disease. Development of hyperinflation during the course of COPD is insidious. Dynamic hyperinflation is highly prevalent in the advanced stages of COPD, and new evidence suggests that it also occurs in many patients with mild disease, independently of the presence of resting hyperinflation. Hyperinflation is clinically relevant for patients with COPD mainly because it contributes to dyspnea, exercise intolerance, skeletal muscle limitations, morbidity, and reduced physical activity levels associated with the disease. Various pharmacological and nonpharmacological interventions have been shown to reduce hyperinflation and delay the onset of ventilatory limitation in patients with COPD. The aim of this review is to address the more recent literature regarding the pathogenesis, assessment, and management of both static and dynamic lung hyperinflation in patients with COPD. We also address the influence of biological sex and obesity and new developments in our understanding of hyperinflation in patients with mild COPD and its evolution during progression of the disease. PMID:24600216

[Treatment of acute respiratory distress syndrome using pressure and volume controlled ventilation with lung protective strategy].

PubMed

Ge, Ying; Wan, Yong; Wang, Da-qing; Su, Xiao-lin; Li, Jun-ying; Chen, Jing

2004-07-01

To investigate the significance and effect of pressure controlled ventilation (PCV) as well as volume controlled ventilation (VCV) by lung protective strategy on respiratory mechanics, blood gas analysis and hemodynamics in patients with acute respiratory distress syndrome (ARDS). Fifty patients with ARDS were randomly divided into PCV and VCV groups with permissive hypercapnia and open lung strategy. Changes in respiratory mechanics, blood gas analysis and hemodynamics were compared between two groups. Peak inspiration pressure (PIP) in PCV group was significantly lower than that in VCV group, while mean pressure of airway (MPaw) was significantly higher than that in VCV after 24 hours mechanical ventilation. After 24 hours mechanical ventilation, there were higher central venous pressure (CVP) and slower heart rate (HR) in two groups, CVP was significantly higher in VCV compared with PCV, and PCV group had slower HR than VCV group, the two groups had no differences in mean blood pressure (MBP) at various intervals. All patients showed no ventilator-induced lung injury. Arterial blood oxygenations were obviously improved in two groups after 24 hours mechanical ventilation, PCV group had better partial pressure of oxygen in artery (PaO2) than VCV group. Both PCV and VCV can improve arterial blood oxygenations, prevent ventilator-induced lung injury, and have less disturbance in hemodynamic parameters. PCV with lung protective ventilatory strategy should be early use for patients with ARDS.

Animal model of grain worker's lung.

PubMed Central

Stepner, N; Broder, I; Baumal, R

1986-01-01

We examined the light microscopic changes in the lungs of rabbits exposed to grain dust for variable periods of time, to determine whether an animal model of grain worker's lung could be developed. Experimental animals were exposed to grain dust at a concentration of 20 mg/m3 for 7 hr/day, 5 days/week, for up to 6 months. The lungs of these rabbits demonstrated a granulomatous interstitial pneumonitis associated with exudation of mononuclear cells into the alveoli and conducting airways. These changes appeared within 5 days of the onset of exposure and reached a peak at 3 weeks but were sustained through the longest exposure interval. No abnormalities were observed in the lungs of control rabbits. These results show three points of consistency with those obtained in epidemiologic studies of grain elevator workers. First, the rapid appearance of the experimental changes suggests that the mechanism of tissue injury may not be immunologic. Second, the occurrence of the histopathologic alterations in the interstitium, alveoli, and airways corresponds with the combined restrictive and obstructive ventilatory defect described in the human epidemiologic studies. Third, the absence of lung fibrosis in rabbits exposed to dust for 6 months suggests that the pneumonitis is reversible. Thus this experimental model shows promise of helping to clarify the nature and mechanism of the adverse pulmonary effects of grain dust. Images FIGURE 1. FIGURE 2. PMID:3709485

Inhaled fentanyl citrate improves exercise endurance during high-intensity constant work rate cycle exercise in chronic obstructive pulmonary disease.

PubMed

Jensen, Dennis; Alsuhail, Abdullah; Viola, Raymond; Dudgeon, Deborah J; Webb, Katherine A; O'Donnell, Denis E

2012-04-01

Activity limitation and dyspnea are the dominant symptoms of chronic obstructive pulmonary disease (COPD). Traditionally, efforts to alleviate these symptoms have focused on improving ventilatory mechanics, reducing ventilatory demand, or both of these in combination. Nevertheless, many patients with COPD remain incapacitated by dyspnea and exercise intolerance despite optimal therapy. To determine the effect of single-dose inhalation of nebulized fentanyl citrate (a μ-opioid agonist drug) on exercise tolerance and dyspnea in COPD. In a randomized, double-blind, placebo-controlled, crossover study, 12 stable patients with COPD (mean ± standard error of the mean post-β(2)-agonist forced expiratory volume in one second [FEV(1)] and FEV(1) to forced vital capacity ratio of 69% ± 4% predicted and 49% ± 3%, respectively) received either nebulized fentanyl citrate (50 mcg) or placebo on two separate days. After each treatment, patients performed pulmonary function tests and a symptom-limited constant work rate cycle exercise test at 75% of their maximum incremental work rate. There were no significant postdose differences in spirometric parameters or plethysmographic lung volumes. Neither the intensity nor the unpleasantness of perceived dyspnea was, on average, significantly different at isotime (5.0 ± 0.6 minutes) or at peak exercise after treatment with fentanyl citrate vs. placebo. Compared with placebo, fentanyl citrate was associated with 1) increased exercise endurance time by 1.30 ± 0.43 minutes or 25% ± 8% (P=0.01); 2) small but consistent increases in dynamic inspiratory capacity by ∼0.10 L at isotime and at peak exercise (both P≤0.03); and 3) no concomitant change in ventilatory demand, breathing pattern, pulmonary gas exchange, and/or cardiometabolic function during exercise. The mean rate of increase in dyspnea intensity (1.2 ± 0.3 vs. 2.9 ± 0.8 Borg units/minute, P=0.03) and unpleasantness ratings (0.5 ± 0.2 vs. 2.9 ± 1.3 Borg units/minute, P=0.06) between isotime and peak exercise was less after treatment with fentanyl citrate vs. placebo. Single-dose inhalation of fentanyl citrate was associated with significant and potentially clinically important improvements in exercise tolerance in COPD. These improvements were accompanied by a delay in the onset of intolerable dyspnea during exercise near the limits of tolerance. Copyright © 2012 U.S. Cancer Pain Relief Committee. Published by Elsevier Inc. All rights reserved.

Ventilatory Management During Normothermic Ex Vivo Lung Perfusion: Effects on Clinical Outcomes.

PubMed

Terragni, Pier Paolo; Fanelli, Vito; Boffini, Massimo; Filippini, Claudia; Cappello, Paola; Ricci, Davide; Del Sorbo, Lorenzo; Faggiano, Chiara; Brazzi, Luca; Frati, Giacomo; Venuta, Federico; Mascia, Luciana; Rinaldi, Mauro; Ranieri, V Marco

2016-05-01

During ex vivo lung perfusion (EVLP), fixed ventilator settings and monitoring of compliance are used to prevent ventilator-induced lung injury (VILI). Analysis of the airway pressure-time curve (stress index) has been proposed to assess the presence of VILI. We tested whether currently proposed ventilator settings expose lungs to VILI during EVLP and whether the stress index could identify VILI better than compliance. Flow, volume, and airway opening pressure were collected continuously during EVLP. Durations of mechanical ventilation, intensive care unit (ICU) and hospital lengths of stay were recorded in lung recipients. Fourteen lungs underwent EVLP and were transplanted. In 5 lungs, 95 ± 2% of the stress index values were within the 0.95 to 1.05 range (protected); in the remaining nine lungs, 69 ± 1% of the values were greater than 1.05 and 15 ± 3% were less than 0.95 (nonprotected). There was a significant (P < 0.05) increase in cytokine concentrations after 4 hours of EVLP in the nonprotected lungs. Durations of mechanical ventilation, ICU, and hospital lengths of stay were shorter in recipients of protected than that of nonprotected lungs (P < 0.05). There was no correlation between compliance during EVLP and duration of mechanical ventilation or ICU and hospital lengths of stay in recipients, but the stress index during EVLP was significantly correlated with the duration of mechanical ventilation and with ICU and hospital lengths of stay (P < 0.05). This small, preliminary study shows that ventilator settings currently proposed for EVLP may expose lungs to VILI. Use of the stress index to personalize ventilator settings needs to be tested in further clinical studies.

Spatiotemporal Aeration and Lung Injury Patterns Are Influenced by the First Inflation Strategy at Birth.

PubMed

Tingay, David G; Rajapaksa, Anushi; Zonneveld, C Elroy; Black, Don; Perkins, Elizabeth J; Adler, Andy; Grychtol, Bartłomiej; Lavizzari, Anna; Frerichs, Inéz; Zahra, Valerie A; Davis, Peter G

2016-02-01

Ineffective aeration during the first inflations at birth creates regional aeration and ventilation defects, initiating injurious pathways. This study aimed to compare a sustained first inflation at birth or dynamic end-expiratory supported recruitment during tidal inflations against ventilation without intentional recruitment on gas exchange, lung mechanics, spatiotemporal regional aeration and tidal ventilation, and regional lung injury in preterm lambs. Lambs (127 ± 2 d gestation), instrumented at birth, were ventilated for 60 minutes from birth with either lung-protective positive pressure ventilation (control) or as per control after either an initial 30 seconds of 40 cm H2O sustained inflation (SI) or an initial stepwise end-expiratory pressure recruitment maneuver during tidal inflations (duration 180 s; open lung ventilation [OLV]). At study completion, molecular markers of lung injury were analyzed. The initial use of an OLV maneuver, but not SI, at birth resulted in improved lung compliance, oxygenation, end-expiratory lung volume, and reduced ventilatory needs compared with control, persisting throughout the study. These changes were due to more uniform inter- and intrasubject gravity-dependent spatiotemporal patterns of aeration (measured using electrical impedance tomography). Spatial distribution of tidal ventilation was more stable after either recruitment maneuver. All strategies caused regional lung injury patterns that mirrored associated regional volume states. Irrespective of strategy, spatiotemporal volume loss was consistently associated with up-regulation of early growth response-1 expression. Our results show that mechanical and molecular consequences of lung aeration at birth are not simply related to rapidity of fluid clearance; they are also related to spatiotemporal pressure-volume interactions within the lung during inflation and deflation.

Improvement in exercise duration, lung function and well-being in G551D-cystic fibrosis patients: a double-blind, placebo-controlled, randomized, cross-over study with ivacaftor treatment.

PubMed

Edgeworth, Deirdre; Keating, Dominic; Ellis, Matthew; Button, Brenda; Williams, Elyssa; Clark, Denise; Tierney, Audrey; Heritier, Stephane; Kotsimbos, Tom; Wilson, John

2017-08-01

G551D, a mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, results in impaired chloride channel function in cystic fibrosis (CF) with multiple end-organ manifestations. The effect of ivacaftor, a CFTR-potentiator, on exercise capacity in CF is unknown. Twenty G551D-CF patients were recruited to a single-centre, double-blind, placebo-controlled, 28-day crossover study of ivacaftor. Variables measured included percentage change from baseline (%Δ) of V O 2 max (maximal oxygen consumption, primary outcome) during cardiopulmonary exercise testing (CPET), relevant other CPET physiological variables, lung function, body mass index (BMI), sweat chloride and disease-specific health related quality of life (QOL) measures (CFQ-R and Alfred Wellness (AWEscore)). %Δ V O 2 max was unchanged compared with placebo as was %Δminute ventilation. However, %Δexercise time (mean 7.3, CI 0.5-14,1, P =0.0222) significantly increased as did %ΔFEV 1 (11.7%, range 5.3-18.1, P <0·005) and %ΔBMI (1.2%, range 0.1-2.3, P =0·0393) whereas sweat chloride decreased (mean -43.4; range -55.5-18.1 mmol·l -1 , P <0·005). Total and activity based domains in both CFQ-R and AWEscore also increased. A positive treatment effect on spirometry, BMI (increased), SCT (decreased) and total and activity based CF-specific QOL measures was expected. However, the lack of discernible improvement in V O 2 max and VE despite other positive changes including spirometric lung function and exercise time with a 28-day ivacaftor intervention suggests that ventilatory parameters are not the sole driver of change in exercise capacity in this study cohort. Investigation over a more prolonged period may delineate the potential interdependencies of the observed discordances over time. ClinicalTrials.gov-NCT01937325. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

Ventilatory demand and dynamic hyperinflation induced during ADL-based tests in Chronic Obstructive Pulmonary Disease patients

PubMed Central

dos Santos, Karoliny; Gulart, Aline A.; Munari, Anelise B.; Karloh, Manuela; Mayer, Anamaria F.

2016-01-01

ABSTRACT Background Airflow limitation frequently leads to the interruption of activities of daily living (ADL) in patients with Chronic Obstructive Pulmonary Disease (COPD). These patients commonly show absence of ventilatory reserve, reduced inspiratory reserve volume, and dynamic hyperinflation (DH). Objective To investigate ventilatory response and DH induced by three ADL-based protocols in COPD patients and compare them to healthy subjects. Method Cross-sectional study. COPD group: 23 patients (65±6 years, FEV1 37.2±15.4%pred); control group: 14 healthy subjects (64±4 years) matched for age, sex, and body mass index. Both groups performed all three tests: Glittre-ADL test; an activity test that involved moving objects on a shelf (TSHELF); and a modified shelf protocol isolating activity with upper limbs (TSHELF-M). Ventilatory response and inspiratory capacity were evaluated. Results Baseline ventilatory variables were similar between groups (p>0.05). The ventilatory demand increased and the inspiratory capacity decreased significantly at the end of the tests in the COPD group. Ventilatory demand and DH were higher (p<0.05) in the TSHELF than in the TSHELF–M in the COPD group (p<0.05). There were no differences in DH between the three tests in the control group (p>0.05) and ventilatory demand increased at the end of the tests (p<0.05) but to a lower extent than the COPD group. Conclusion The TSHELF induces similar ventilatory responses to the Glittre-ADL test in COPD patients with higher ventilatory demand and DH. In contrast, the ventilatory response was attenuated in the TSHELF-M, suggesting that squatting and bending down during the Glittre-ADL test could trigger significant ventilatory overload. PMID:27333482

The Gross Morphology and Histochemistry of Respiratory Muscles in Bottlenose Dolphins, Tursiops truncatus

PubMed Central

Cotten, Pamela B.; Piscitelli, Marina A.; McLellan, William A.; Rommel, Sentiel A.; Dearolf, Jennifer L.; Pabst, D. Ann

2011-01-01

Most mammals possess stamina because their locomotor and respiratory (i.e., ventilatory) systems are mechanically coupled. These systems are decoupled, however, in bottlenose dolphins (Tursiops truncatus) as they swim on a breath-hold. Locomotion and ventilation are coupled only during their brief surfacing event, when they respire explosively (up to 90% of total lung volume in approximately 0.3s) (Ridgway et al., 1969). The predominantly slow-twitch fiber profile of their diaphragm (Dearolf, 2003) suggests that this muscle does not likely power their rapid ventilatory event. Based upon Bramble's (1989) biomechanical model of locomotor-respiratory coupling in galloping mammals, it was hypothesized that locomotor muscles function to power ventilation in bottlenose dolphins. It was further hypothesized that these muscles would be composed predominantly of fast-twitch fibers to facilitate the bottlenose dolphin's rapid ventilation. The gross morphology of cranio-cervical (scalenus, sternocephalicus, sternohyoid), thoracic (intercostals, transverse thoracis), and lumbo-pelvic (hypaxialis, rectus abdominis, abdominal obliques) muscles (n=7) and the fiber-type profiles (n=6) of selected muscles (scalenus, sternocephalicus, sternohyoid, rectus abdominis) of bottlenose dolphins were investigated. Physical manipulations of excised thoracic units were carried out to investigate potential actions of these muscles. Results suggest that the cranio-cervical muscles act to draw the sternum and associated ribs cranio-dorsally, which flares the ribs laterally, and increases the thoracic cavity volume required for inspiration. The lumbo-pelvic muscles act to draw the sternum and caudal ribs caudally, which decreases the volumes of the thoracic and abdominal cavities required for expiration. All muscles investigated were composed predominantly of fast-twitch fibers (range 61-88% by area) and appear histochemically poised for rapid contraction. These combined results suggest that dolphins utilize muscles, similar to those used by galloping mammals, to power their explosive ventilation. PMID:18777569

The weighty issue of obesity in paediatric respiratory medicine.

PubMed

Fitzgerald, Dominic A

2017-09-01

Some have observed that developed world is fat and getting fatter. This is even extending into the developing world, and it is important to appreciate that the consequences of childhood obesity last into adulthood and are associated with premature death. From the paediatric respiratory perspective, the deposition of excess adipose tissue in the thoraco-abdominal region begins early in life and is believed to alter diaphragm mobility and chest wall expansion, reduce lung compliance, and result in a rapid shallow breathing pattern with an increased work of breathing and reduction in maximum ventilatory capacity. This results in respiratory symptoms of exertional dyspnoea related to deconditioning which may present as exercise limitation, leading to confusion with common lung diseases such as asthma. The manifestations of the increasingly prevalent problems of overweight and obesity in young people and their interaction with common conditions of asthma and obstructive sleep apnoea will be discussed. Copyright © 2017. Published by Elsevier Ltd.

Inhalation therapy in mechanical ventilation

PubMed Central

Maccari, Juçara Gasparetto; Teixeira, Cassiano; Gazzana, Marcelo Basso; Savi, Augusto; Dexheimer-Neto, Felippe Leopoldo; Knorst, Marli Maria

2015-01-01

Patients with obstructive lung disease often require ventilatory support via invasive or noninvasive mechanical ventilation, depending on the severity of the exacerbation. The use of inhaled bronchodilators can significantly reduce airway resistance, contributing to the improvement of respiratory mechanics and patient-ventilator synchrony. Although various studies have been published on this topic, little is known about the effectiveness of the bronchodilators routinely prescribed for patients on mechanical ventilation or about the deposition of those drugs throughout the lungs. The inhaled bronchodilators most commonly used in ICUs are beta adrenergic agonists and anticholinergics. Various factors might influence the effect of bronchodilators, including ventilation mode, position of the spacer in the circuit, tube size, formulation, drug dose, severity of the disease, and patient-ventilator synchrony. Knowledge of the pharmacological properties of bronchodilators and the appropriate techniques for their administration is fundamental to optimizing the treatment of these patients. PMID:26578139

Ventilatory and cardiometabolic responses to unilateral sanding in elderly women with ischemic heart disease: a pilot study.

PubMed

Muraki, T; Kujime, K; Kaneko, T; Su, M; Ueba, Y

1991-08-01

This study was undertaken to investigate how 8 elderly women with ischemic heart disease would respond to a unilateral sanding activity. Three ventilatory measures-expiratory tidal volume, respiratory rate, and expiratory volume--and four cardiometabolic measures--metabolic equivalent, systolic blood pressure, heart rate, and pressure rate product--were continuously recorded during the sanding activity. The two independent variables were angle of the sanding board and sanding velocity. The activity was graded to yield five conditions: (a) sitting at rest; (b) 0 degrees at 15 cycles per min (cpm); (c) 0 degrees at 30 cpm; (d) 15 degrees at 15 cpm; and (e) 15 degrees at 30 cpm. The findings indicated that increasing the angle of the board while holding the velocity constant did not always increase the mean values of the ventilatory and cardiometabolic measures. However, increasing the velocity while holding the angle constant always increased the mean values of the dependent variables. The data also indicated that the metabolic equivalent reached during the sanding activity was no greater than 2, which corresponds to a light activity, such as playing a musical instrument. Replication of the study with a larger sample size may further elucidate the behavior of these two functions during a graded sanding activity. In the present study, a unilateral sanding activity by elderly patients with cardiac impairment was shown to provide valuable data on ventilatory and cardiometabolic functions. The study also demonstrated that a unilateral sanding activity can be safely used as a graded activity in occupational therapy for the cardiac rehabilitation of elderly women.

Clinical review: Long-term noninvasive ventilation

PubMed Central

Robert, Dominique; Argaud, Laurent

2007-01-01

Noninvasive positive ventilation has undergone a remarkable evolution over the past decades and is assuming an important role in the management of both acute and chronic respiratory failure. Long-term ventilatory support should be considered a standard of care to treat selected patients following an intensive care unit (ICU) stay. In this setting, appropriate use of noninvasive ventilation can be expected to improve patient outcomes, reduce ICU admission, enhance patient comfort, and increase the efficiency of health care resource utilization. Current literature indicates that noninvasive ventilation improves and stabilizes the clinical course of many patients with chronic ventilatory failure. Noninvasive ventilation also permits long-term mechanical ventilation to be an acceptable option for patients who otherwise would not have been treated if tracheostomy were the only alternative. Nevertheless, these results appear to be better in patients with neuromuscular/-parietal disorders than in chronic obstructive pulmonary disease. This clinical review will address the use of noninvasive ventilation (not including continuous positive airway pressure) mainly in diseases responsible for chronic hypoventilation (that is, restrictive disorders, including neuromuscular disease and lung disease) and incidentally in others such as obstructive sleep apnea or problems of central drive. PMID:17419882

Controlled invasive mechanical ventilation strategies in obese patients undergoing surgery.

PubMed

Maia, Lígia de Albuquerque; Silva, Pedro Leme; Pelosi, Paolo; Rocco, Patricia Rieken Macedo

2017-06-01

The obesity prevalence is increasing in surgical population. As the number of obese surgical patients increases, so does the demand for mechanical ventilation. Nevertheless, ventilatory strategies in this population are challenging, since obesity results in pathophysiological changes in respiratory function. Areas covered: We reviewed the impact of obesity on respiratory system and the effects of controlled invasive mechanical ventilation strategies in obese patients undergoing surgery. To date, there is no consensus regarding the optimal invasive mechanical ventilation strategy for obese surgical patients, and no evidence that possible intraoperative beneficial effects on oxygenation and mechanics translate into better postoperative pulmonary function or improved outcomes. Expert commentary: Before determining the ideal intraoperative ventilation strategy, it is important to analyze the pathophysiology and comorbidities of each obese patient. Protective ventilation with low tidal volume, driving pressure, energy, and mechanical power should be employed during surgery; however, further studies are required to clarify the most effective ventilation strategies, such as the optimal positive end-expiratory pressure and whether recruitment maneuvers minimize lung injury. In this context, an ongoing trial of intraoperative ventilation in obese patients (PROBESE) should help determine the mechanical ventilation strategy that best improves clinical outcome in patients with body mass index≥35kg/m 2 .

Deposition and dispersion of 1-micrometer aerosol boluses in the human lung: effect of micro- and hypergravity

NASA Technical Reports Server (NTRS)

Darquenne, C.; West, J. B.; Prisk, G. K.

1998-01-01

We performed bolus inhalations of 1-micrometer particles in four subjects on the ground (1 G) and during parabolic flights both in microgravity (microG) and in approximately 1.6 G. Boluses of approximately 70 ml were inhaled at different points in an inspiration from residual volume to 1 liter above functional residual capacity. The volume of air inhaled after the bolus [the penetration volume (Vp)] ranged from 200 to 1,500 ml. Aerosol concentration and flow rate were continuously measured at the mouth. The deposition, dispersion, and position of the bolus in the expired gas were calculated from these data. For Vp >/=400 ml, both deposition and dispersion increased with Vp and were strongly gravity dependent, with the greatest deposition and dispersion occurring for the largest G level. At Vp = 800 ml, deposition and dispersion increased from 33.9% and 319 ml in microG to 56.9% and 573 ml at approximately 1.6 G, respectively (P < 0.05). At each G level, the bolus was expired at a smaller volume than Vp, and this volume became smaller with increasing Vp. Although dispersion was lower in microG than in 1 G and approximately 1.6 G, it still increased steadily with increasing Vp, showing that nongravitational ventilatory inhomogeneity is partly responsible for dispersion in the human lung.

Ventilatory protective strategies during thoracic surgery: effects of alveolar recruitment maneuver and low-tidal volume ventilation on lung density distribution.

PubMed

Kozian, Alf; Schilling, Thomas; Schütze, Hartmut; Senturk, Mert; Hachenberg, Thomas; Hedenstierna, Göran

2011-05-01

The increased tidal volume (V(T)) applied to the ventilated lung during one-lung ventilation (OLV) enhances cyclic alveolar recruitment and mechanical stress. It is unknown whether alveolar recruitment maneuvers (ARMs) and reduced V(T) may influence tidal recruitment and lung density. Therefore, the effects of ARM and OLV with different V(T) on pulmonary gas/tissue distribution are examined. Eight anesthetized piglets were mechanically ventilated (V(T) = 10 ml/kg). A defined ARM was applied to the whole lung (40 cm H(2)O for 10 s). Spiral computed tomographic lung scans were acquired before and after ARM. Thereafter, the lungs were separated with an endobronchial blocker. The pigs were randomized to receive OLV in the dependent lung with a V(T) of either 5 or 10 ml/kg. Computed tomography was repeated during and after OLV. The voxels were categorized by density intervals (i.e., atelectasis, poorly aerated, normally aerated, or overaerated). Tidal recruitment was defined as the addition of gas to collapsed lung regions. The dependent lung contained atelectatic (56 ± 10 ml), poorly aerated (183 ± 10 ml), and normally aerated (187 ± 29 ml) regions before ARM. After ARM, lung volume and aeration increased (426 ± 35 vs. 526 ± 69 ml). Respiratory compliance enhanced, and tidal recruitment decreased (95% vs. 79% of the whole end-expiratory lung volume). OLV with 10 ml/kg further increased aeration (atelectasis, 15 ± 2 ml; poorly aerated, 94 ± 24 ml; normally aerated, 580 ± 98 ml) and tidal recruitment (81% of the dependent lung). OLV with 5 ml/kg did not affect tidal recruitment or lung density distribution. (Data are given as mean ± SD.) The ARM improves aeration and respiratory mechanics. In contrast to OLV with high V(T), OLV with reduced V(T) does not reinforce tidal recruitment, indicating decreased mechanical stress.

Heat and moisture exchangers and heated humidifiers in acute lung injury/acute respiratory distress syndrome patients. Effects on respiratory mechanics and gas exchange.

PubMed

Morán, Indalecio; Bellapart, Judith; Vari, Alessandra; Mancebo, Jordi

2006-04-01

To compare, in acute lung injury/acute respiratory distress syndrome (ALI/ARDS) patients, the short-term effects of heat and moisture exchangers (HME) and heated humidifiers (HH) on gas exchange, and also on respiratory system mechanics when isocapnic conditions are met. Prospective open clinical study. Intensive Care Service. Seventeen invasively ventilated ALI/ARDS patients. The study was performed in three phases: (1) determinations were made during basal ventilatory settings with HME; (2) basal ventilatory settings were maintained and HME was replaced by an HH; (3) using the same HH, tidal volume (Vt) was decreased until basal PaCO2 levels were reached. FiO2, respiratory rate and PEEP were kept unchanged. Respiratory mechanics, Vdphys, gas exchange and hemodynamic parameters were obtained at each phase. By using HH instead of HME and without changing Vt, PaCO2 decreased from 46+/-9 to 40+/-8 mmHg (p<0.001) and Vdphys decreased from 352+/-63 to 310+/-74 ml (p<0.001). Comparing the first phase with the third, Vt decreased from 521+/-106 to 440+/-118 ml (p<0.001) without significant changes in PaCO2, Vd/Vt decreased from 0.69+/-0.11 to 0.62+/-0.12 (p<0.001), plateau airway pressure decreased from 25+/-6 to 21+/-6 cmH2O (p<0.001) and respiratory system compliance improved from 35+/-12 to 42+/-15 ml/cmH2O (p<0.001). PaO2 remained unchanged in the three phases. Reducing dead space with the use of HH decreases PaCO2 and more importantly, if isocapnic conditions are maintained by reducing Vt, this strategy improves respiratory system compliance and reduces plateau airway pressure.

Pulmonary circulation and gas exchange at exercise in Sherpas at high altitude.

PubMed

Faoro, Vitalie; Huez, Sandrine; Vanderpool, Rebecca; Groepenhoff, Herman; de Bisschop, Claire; Martinot, Jean-Benot; Lamotte, Michel; Pavelescu, Adriana; Guénard, Hervé; Naeije, Robert

2014-04-01

Tibetans have been reported to present with a unique phenotypic adaptation to high altitude characterized by higher resting ventilation and arterial oxygen saturation, no excessive polycythemia, and lower pulmonary arterial pressures (Ppa) compared with other high-altitude populations. How this affects exercise capacity is not exactly known. We measured aerobic exercise capacity during an incremental cardiopulmonary exercise test, lung diffusing capacity for carbon monoxide (DL(CO)) and nitric oxide (DL(NO)) at rest, and mean Ppa (mPpa) and cardiac output by echocardiography at rest and at exercise in 13 Sherpas and in 13 acclimatized lowlander controls at the altitude of 5,050 m in Nepal. In Sherpas vs. lowlanders, arterial oxygen saturation was 86 ± 1 vs. 83 ± 2% (mean ± SE; P = nonsignificant), mPpa at rest 19 ± 1 vs. 23 ± 1 mmHg (P < 0.05), DL(CO) corrected for hemoglobin 61 ± 4 vs. 37 ± 2 ml · min(-1) · mmHg(-1) (P < 0.001), DL(NO) 226 ± 18 vs. 153 ± 9 ml · min(-1) · mmHg(-1) (P < 0.001), maximum oxygen uptake 32 ± 3 vs. 28 ± 1 ml · kg(-1) · min(-1) (P = nonsignificant), and ventilatory equivalent for carbon dioxide at anaerobic threshold 40 ± 2 vs. 48 ± 2 (P < 0.001). Maximum oxygen uptake was correlated directly to DL(CO) and inversely to the slope of mPpa-cardiac index relationships in both Sherpas and acclimatized lowlanders. We conclude that Sherpas compared with acclimatized lowlanders have an unremarkable aerobic exercise capacity, but with less pronounced pulmonary hypertension, lower ventilatory responses, and higher lung diffusing capacity.

Upper airway CO2 receptors in tegu lizards: localization and ventilatory sensitivity.

PubMed

Coates, E L; Ballam, G O

1987-01-01

1. Tidal volume, end-tidal CO2, and ventilatory frequency in Tupinambis nigropunctatus were measured in response to CO2 (1-4%) delivered to either the mouth or nares. Additionally, the sensitivity of the ventilatory response to nasal CO2 was evaluated at CO2 concentrations less than 1%. The ventilatory parameters were also measured in response to CO2 (1-4%) delivered to the nares after the olfactory peduncle was transected. 2. It was found that (0.4-4%) nasal CO2 depressed ventilatory frequency by 9% to 83% respectively, while tidal volume was not significantly altered. CO2 (1-4%) delivered to the mouth produced no apparent changes in any of the ventilatory parameters. Following transection of the olfactory peduncle, nasal CO2 was ineffective in producing any change in ventilatory frequency or depth. 3. These findings indicate that CO2-sensitive receptors are located in either the nasal or vomeronasal membranes of tegu lizards and that the olfactory peduncle must be intact for these receptors to affect ventilatory changes in response to elevated CO2 concentrations. The receptors are capable of mediating a ventilatory response to CO2 concentrations lower than those found in either expired air or in confined spaces such as occupied burrows. 4. The discrepancies in the ventilatory responses of lizards and snakes to inspired CO2 reported in past experiments may be partially explained by the presence of nasal or vomeronasal CO2-sensitive receptors.

[Ventilatory dysfunction in motor neuron disease: when and how to act?].

PubMed

Rocha, J Afonso; Miranda, M J

2007-01-01

Amyotrophic lateral sclerosis is a devastating progressive neurodegenerative disorder, involving motor neurons in the cerebral cortex, brainstem and spinal cord. Mean duration of survival from the time of diagnosis is around 15 months, being pulmonary complications and respiratory failure responsible for more than 85% of deaths. Albeit the inevitability of respiratory failure and short-term death, standardized intervention protocols have been shown to significantly delay the need for invasive ventilatory support, thus prolonging survival and enhancing quality of life. The authors present an intervention protocol based on clinical progression and respiratory parameters. Decisions regarding initiation of non-invasive positive pressure ventilation (NIPPV) and mechanically assisted coughing, depend on development of symptoms of hypoventilation and on objective deterioration of respiratory parameters especially in what concerns bulbar muscle function. These include maximum inspiratory capacity (MIC), difference between MIC and vital capacity (MIC-VC), and assisted peak cough flow (PCF). These standardized protocols along with patient and caregivers education, allow for improved quality of life, prolonged survival and delay or eventually prevent the need for tracheotomy and invasive ventilatory support. Supplemental oxygen should be avoided in these patients, since it precludes use of oxymetry as feedback for titrating NIPPV and MAC, and is associated with decreased ventilatory drive and aggravated hypercapnia.

Consequences of peripheral chemoreflex inhibition with low-dose dopamine in humans

PubMed Central

Niewinski, Piotr; Tubek, Stanislaw; Banasiak, Waldemar; Paton, Julian F R; Ponikowski, Piotr

2014-01-01

Low-dose dopamine inhibits peripheral chemoreceptors and attenuates the hypoxic ventilatory response (HVR) in humans. However, it is unknown: (1) whether it also modulates the haemodynamic reactions to acute hypoxia, (2) whether it also modulates cardiac baroreflex sensitivity (BRS) and (3) if there is any effect of dopamine withdrawal. We performed a double-blind, placebo-controlled study on 11 healthy male volunteers. At sea level over 2 days every subject was administered low-dose dopamine (2 μg kg–1 min–1) or saline infusion, during which we assessed both ventilatory and haemodynamic responses to acute hypoxia. Separately, we evaluated effects of initiation and withdrawal of each infusion and BRS. The initiation of dopamine infusion did not affect minute ventilation (MV) or mean blood pressure (MAP), but increased both heart rate (HR) and cardiac output. Concomitantly, it decreased systemic vascular resistance. Dopamine blunted the ventilatory, MAP and HR reactions (hypertension, tachycardia) to acute hypoxia. Dopamine attenuated cardiac BRS to falling blood pressure. Dopamine withdrawal evoked an increase in MV. The magnitude of the increment in MV due to dopamine withdrawal correlated with the size of the HVR and depended on the duration of dopamine administration. The ventilatory reaction to dopamine withdrawal constitutes a novel index of peripheral chemoreceptor function. PMID:24396060

[Respiratory symptoms and obstructive ventilatory disorder in Tunisian woman exposed to biomass].

PubMed

Kwas, H; Rahmouni, N; Zendah, I; Ghedira, H

2017-04-01

In some Tunisian cities, especially semi-urbanized, the exposure to the smoke produced during combustion of the biomass, main source of pollution of indoor air, remains prevalent among non-smoking women. To assess the relationship between exposure to biomass smoke and the presence of obstructive ventilatory disorder in the non-smoking women in semi-urban areas of Tunisia. Cross etiological study, using a questionnaire, including 140 non-smoking women responsible for cooking and/or exposed during heating by traditional means with objective measurement of their respiratory functions. We found 81 women exposed to biomass for a period of≥20 hours-years and 59 unexposed women. Exposed women reported more respiratory symptoms namely exertional dyspnea and/or chronic cough than unexposed. Of the 140 women, 14 women have an FEV/FEV6<70% of which 13 are exposed to biomass. We found a correlation between respiratory symptoms and obstructive ventilatory disorder in exposed women. The air pollution inside the home during the traditional activities of cooking and/or heating is a respiratory risk factor for non-smoking women over the age of 30 years. Exposure to biomass smoke can cause chronic respiratory symptoms and persistent obstructive ventilatory disorder that can consistent with COPD. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Isolated lung transplantation for end-stage lung disease: a viable therapy.

PubMed

Egan, T M; Westerman, J H; Lambert, C J; Detterbeck, F C; Thompson, J T; Mill, M R; Keagy, B A; Paradowski, L J; Wilcox, B R

1992-04-01

Since January 1990, we have performed 29 isolated lung transplantations in 28 patients with end-stage lung disease (12 single, 16 bilateral). Recipient diagnoses were: cystic fibrosis (11), chronic obstructive pulmonary disease (6), pulmonary fibrosis (6), eosinophilic granulomatosis (1), postinfectious lung disease (1), adult respiratory distress syndrome (1), and primary pulmonary hypertension (2). There have been four deaths, two in patients with pulmonary fibrosis and two in patients with primary pulmonary hypertension. Four patients have undergone transplantation while on ventilatory support for respiratory failure (2 with cystic fibrosis, 1 having redo lung transplantation with cystic fibrosis, and 1 with adult respiratory distress syndrome); all of these have survived. Six patients required cardiopulmonary bypass, which was associated with increased transfusion requirement. All patients 2 months after discharge have returned to an active life-style, except for 2 patients who currently await retransplantation. Preoperative pulmonary rehabilitation has resulted in significant improvement in exercise performance in all patients. Immunosuppression consists of cyclosporine, azathioprine, and antilymphoblast globulin (University of Minnesota), withholding systemic steroids in the early postoperative period. We have employed bronchial omentopexy in all but four transplants; there has been one partial bronchial dehiscence, two instances of bronchomalacia requiring internal stenting, and one airway stenosis. Cytomegalovirus disease has been seen frequently (15 cases), but has responded well to treatment with ganciclovir. Other complication shave included one drug-related prolonged postoperative ventilation, thrombosis of a left lung after bilateral lung transplantation requiring retransplantation, five episodes of unilateral phrenic nerve palsy after bilateral lung transplantation (4 resolved), and the requirement of massive transfusion (greater than 10 units) in 5 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

[Unilateral lung transplant in a case of terminal pulmonary fibrosis].

PubMed

Santillán-Doherty, P

1990-01-01

Up to 1980, less than 40 lung transplants had been reported worldwide without any success. The factors influencing these poor results were related to complications at the bronchial anastomosis and ineffective immunosuppressive regimens. The development of new immunosuppressive drugs has permitted the reevaluation of lung transplantation as a therapeutic option. The success with heart-lung transplantation stimulated the development of clinical human single-lung and double-lung transplantation. However the world experience is still scarce. In our institution we have developed experimental work leading to the establishment of a lung transplant program. This paper describes our first single lung transplant patient. The patient, a 33 year old man with end-stage pulmonary fibrosis, was totally oxygen dependant, maintaining arterial blood oxygen levels below 40 mmHg without oxygen supplementation and confined to a wheelchair. A single left lung transplant was performed from a young brain-dead donor. The bronchial anastomosis was protected with an omental flap. The immunosuppressive regimen was based on cyclosporin A and azathioprine from the beginning, adding prednisone on the third postoperative week. There has been only one episode suggestive of acute rejection which was managed with methylprednisolone. On the 9th postoperative week the patient developed a bronchial stenoses at the anastomotic site which required dilation and stenting with an endobronchial silastic stent. His clinical course has been uneventful since then. His ventilatory parameters showed an increase of vital capacity from 900 to 2100 mL and his FEV1 from 700 to 1500 mL. His gas exchange has been normal with arterial blood gas oxygen above 60 mmHg and oxygen saturation above 94%.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of fenoterol on ventilatory responses to hypoxia and hypercapnia in normal subjects.

PubMed Central

Yoshiike, Y.; Suzuki, S.; Watanuki, Y.; Okubo, T.

1995-01-01

BACKGROUND--The effects of beta 2 adrenergic agonists on chemoreceptors remain controversial. This study was designed to examine whether fenoterol, a beta 2 adrenergic agonist, increases the ventilatory responses to hypercapnia (HCVR) and hypoxia (HVR) in normal subjects. METHODS--HCVR was tested with a rebreathing method and HVR was examined with a progressive isocapnic hypoxic method in 11 normal subjects. Both HCVR and HVR were assessed by the slope of occlusion pressure (P0.1) or ventilation (VE) plotted against end tidal carbon dioxide pressure and arterial oxygen saturation, respectively. Respiratory muscle strength, spirometric values and lung volume were measured. After a single oral administration of 5 mg fenoterol or placebo HCVR and HVR were evaluated. RESULTS--Fenoterol treatment did not change the specific airway conductance or forced expiratory volume in one second. Respiratory muscle strength did not change. Fenoterol increased the slope of the HCVR of both P0.1 (from 0.251 (0.116) to 0.386 (0.206) kPa/kPa, average increase 71%) and VE (from 10.7 (3.4) to 15.1 (4.2) l/min/kPa, average increase 52%), and shifted the response curves to higher values. For the HVR fenoterol increased the slopes of both P0.1 and VE (from -4.06 (2.00) x 10(-3) to -7.99 (4.29) x 10(-3) kPa/%, an average increase of 83%, and from -0.221 (0.070) to -0.313 (0.112) l/min/%, a 44.5% increase, respectively), and shifted the response curves to higher values. CONCLUSION--Acute administration of fenoterol increases the ventilatory responses to both hypercapnia and hypoxia in normal subjects. PMID:7701451

Comparing four non-invasive methods to determine the ventilatory anaerobic threshold during cardiopulmonary exercise testing in children with congenital heart or lung disease.

PubMed

Visschers, Naomi C A; Hulzebos, Erik H; van Brussel, Marco; Takken, Tim

2015-11-01

The ventilatory anaerobic threshold (VAT) is an important method to assess the aerobic fitness in patients with cardiopulmonary disease. Several methods exist to determine the VAT; however, there is no consensus which of these methods is the most accurate. To compare four different non-invasive methods for the determination of the VAT via respiratory gas exchange analysis during a cardiopulmonary exercise test (CPET). A secondary objective is to determine the interobserver reliability of the VAT. CPET data of 30 children diagnosed with either cystic fibrosis (CF; N = 15) or with a surgically corrected dextro-transposition of the great arteries (asoTGA; N = 15) were included. No significant differences were found between conditions or among testers. The RER = 1 method differed the most compared to the other methods, showing significant higher results in all six variables. The PET-O2 method differed significantly on five of six and four of six exercise variables with the V-slope method and the VentEq method, respectively. The V-slope and the VentEq method differed significantly on one of six exercise variables. Ten of thirteen ICCs that were >0.80 had a 95% CI > 0.70. The RER = 1 method and the V-slope method had the highest number of significant ICCs and 95% CIs. The V-slope method, the ventilatory equivalent method and the PET-O2 method are comparable and reliable methods to determine the VAT during CPET in children with CF or asoTGA. © 2014 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Polygraphic respiratory events during sleep with noninvasive ventilation in children: description, prevalence, and clinical consequences.

PubMed

Caldarelli, Valeria; Borel, Jean Christian; Khirani, Sonia; Ramirez, Adriana; Cutrera, Renato; Pépin, Jean-Louis; Fauroux, Brigitte

2013-04-01

The optimal monitoring during sleep with noninvasive positive pressure ventilation (NPPV) has not been validated in children. The aim of the study was to describe on polygraphic (PG) recordings the respiratory events and associated autonomic arousals (AA) and/or 3 % desaturations (DS3%) during nocturnal NPPV. This was a prospective descriptive study performed in the pulmonology unit of a pediatric university hospital. Consecutive patients admitted for routine follow-up of long-term NPPV were enrolled. Nocturnal PG during sleep with NPPV was performed. A second PG was performed after adjustment of the ventilatory settings when a respiratory event occurred more than 50 times/h. The PG tracings of 39 patients (age range 1-18 years) were analyzed. Underlying diagnoses included neuromuscular disease (n = 13), obstructive sleep apnea (n = 15), and lung disease (n = 11). Unintentional leaks, patient-ventilator asynchronies, decrease in ventilatory drive, upper airway obstruction with or without reduction of ventilatory drive, and mixed events were observed in 27, 33, 10, 11, 12, and 3 % of the patients, respectively. A predominant respiratory event was observed in all patients. The mean duration spent with respiratory events was 32 ± 30 % (range 3-96 %) of total recording time. Unintentional leaks were the most frequently associated with AA, whereas patient-ventilator asynchronies were rarely associated with AA or DS3%. In eight re-evaluated patients, a decrease in the main event was observed (p = 0.005). Respiratory events during sleep with NPPV are common in children treated with long-term NPPV. Consequences of respiratory events vary according to the type of event with unintentional leaks being associated preferentially with AA.

Overview of Nitrogen Dioxide Effects on the Lung with Emphasis on Military Relevance

DTIC Science & Technology

1994-01-01

toxicity in humans is supportive therapy directed at hypoxemia, ventilatory failure, infection and any other complica- tions. Steroids, N - acetylcysteine ...bI.Irk) 2 AEPOqi OATI! I R(PO’lT fYPI AND) OA iT COV~iM)( A u g u s t 1 9 9 /4 [ ’ tJ, , t j, N __ I 4. Ti[t{ AND SUSTr I 5 4u4ING NUM8[PS Overview ot i...Respiratory Research (SGRI)-JWII-lE) Division of Medicine N /A Walter Reed Army Institute of Research Washington, DC 20307-5100 I-I I. SUP"LEMENTARY NOTES

Temporary banding of the gastroesophageal junction in the critically ill neonate with esophageal atresia and tracheoesophageal fistula.

PubMed

Fagelman, K M; Boyarsky, A

1985-09-01

Patients with esophageal atresia and a distal tracheoesophageal fistula with associated conditions contributing to decreased pulmonary compliance present special problems in management. In the face of positive pressure ventilation, the fistula acts as a vent preventing adequate ventilatory effort from reaching the lungs. A thoracic approach to ligate or divide the fistula carries with it a high mortality rate. A technique is described whereby a silicone rubber band is applied to the gastroesophageal junction to effectively occlude the esophagus. It is designed so that is can be adjusted or removed, without operative intervention, according to the patient's clinical course and growth.

Endoscopic lung volume reduction coil treatment in patients with chronic hypercapnic respiratory failure: an observational study.

PubMed

Simon, Marcel; Harbaum, Lars; Oqueka, Tim; Kluge, Stefan; Klose, Hans

2017-01-01

Endoscopic lung volume reduction coil (LVRC) treatment is an option for selected patients with severe emphysema. In the advanced stages, emphysema leads to respiratory failure: hypoxemia and eventually chronic hypercapnic respiratory failure. It can be hypothesized that LVRC treatment, a procedure targeting hyperinflation and thereby reducing ventilatory workload, may be especially beneficial in patients with chronic hypercapnic respiratory failure. This study was conducted to gain first insights into the effects and the safety of LVRC treatment in patients with emphysema and chronic hypercapnic respiratory failure. A retrospective observational study conducted in the Department of Respiratory Medicine at the University Medical Center Hamburg-Eppendorf, Germany on all patients with chronic hypercapnic respiratory failure in whom bilateral LVRC treatment was performed between 1 April 2012 and 30 September 2015. During the study period, bilateral LVRC treatment was performed in 10 patients with chronic hypercapnic respiratory failure. Compared with baseline, bilateral LVRC treatment led to a significant increase in mean forced expiratory volume in one second (FEV 1 ) from 0.5 ± 0.1 l to 0.6 ± 0.2 l ( p = 0.004), a decrease in residual volume (RV) from 6.1 ± 0.9 l to 5.6 ± 1.1 l ( p = 0.02) and a reduction in partial pressure of carbon dioxide in arterial blood (PaCO 2 ) from 53 ± 5 mmHg to 48 ± 4 mmHg ( p = 0.03). One case of hemoptysis requiring readmission to hospital was the only severe adverse event. LVRC treatment was safe and effective in patients with nonsevere chronic hypercapnic respiratory failure. It led not only to an improvement in lung function but also to a significant decrease in PaCO 2 .

Dynamic loop gain increases upon adopting the supine body position during sleep in patients with obstructive sleep apnoea.

PubMed

Joosten, Simon A; Landry, Shane A; Sands, Scott A; Terrill, Philip I; Mann, Dwayne; Andara, Christopher; Skuza, Elizabeth; Turton, Anthony; Berger, Philip; Hamilton, Garun S; Edwards, Bradley A

2017-11-01

Obstructive sleep apnoea (OSA) is typically worse in the supine versus lateral sleeping position. One potential factor driving this observation is a decrease in lung volume in the supine position which is expected by theory to increase a key OSA pathogenic factor: dynamic ventilatory control instability (i.e. loop gain). We aimed to quantify dynamic loop gain in OSA patients in the lateral and supine positions, and to explore the relationship between change in dynamic loop gain and change in lung volume with position. Data from 20 patients enrolled in previous studies on the effect of body position on OSA pathogenesis were retrospectively analysed. Dynamic loop gain was calculated from routinely collected polysomnographic signals using a previously validated mathematical model. Lung volumes were measured in the awake state with a nitrogen washout technique. Dynamic loop gain was significantly higher in the supine than in the lateral position (0.77 ± 0.15 vs 0.68 ± 0.14, P = 0.012). Supine functional residual capacity (FRC) was significantly lower than lateral FRC (81.0 ± 15.4% vs 87.3 ± 18.4% of the seated FRC, P = 0.021). The reduced FRC we observed on moving to the supine position was predicted by theory to increase loop gain by 10.2 (0.6, 17.1)%, a value similar to the observed increase of 8.4 (-1.5, 31.0)%. Dynamic loop gain increased by a small but statistically significant amount when moving from the lateral to supine position and this may, in part, contribute to the worsening of OSA in the supine sleeping position. © 2017 Asian Pacific Society of Respirology.

Exercise Ventilatory Limitation: The Role Of Expiratory Flow Limitation

PubMed Central

Babb, Tony G.

2012-01-01

Ventilatory limitation to exercise remains an important unresolved clinical issue; as a result, many individuals misinterpret the effects of expiratory flow limitation as an all-or-nothing phenomenon. Expiratory flow limitation is not all-or-none; approaching maximal expiratory flow can have important effects not only on ventilatory capacity but also on breathing mechanics, ventilatory control, and possibly exertional dyspnea and exercise intolerance. PMID:23038244

Open-lung protective ventilation with pressure control ventilation, high-frequency oscillation, and intratracheal pulmonary ventilation results in similar gas exchange, hemodynamics, and lung mechanics.

PubMed

Sedeek, Khaled A; Takeuchi, Muneyuki; Suchodolski, Klaudiusz; Vargas, Sara O; Shimaoka, Motomu; Schnitzer, Jay J; Kacmarek, Robert M

2003-11-01

Pressure control ventilation (PCV), high-frequency oscillation (HFO), and intratracheal pulmonary ventilation (ITPV) may all be used to provide lung protective ventilation in acute respiratory distress syndrome, but the specific approach that is optimal remains controversial. Saline lavage was used to produce acute respiratory distress syndrome in 21 sheep randomly assigned to receive PCV, HFO, or ITPV as follows: positive end-expiratory pressure (PCV and ITPV) and mean airway pressure (HFO) were set in a pressure-decreasing manner after lung recruitment that achieved a ratio of Pao2/Fio2 > 400 mmHg. Respiratory rates were 30 breaths/min, 120 breaths/min, and 8 Hz, respectively, for PCV, ITPV, and HFO. Eucapnia was targeted with peak carinal pressure of no more than 35 cm H2O. Animals were then ventilated for 4 h. There were no differences among groups in gas exchange, lung mechanics, or hemodynamics. Tidal volume (PCV, 8.9 +/- 2.1 ml/kg; ITPV, 2.7 +/- 0.8 ml/kg; HFO, approximately 2.0 ml/kg) and peak carinal pressure (PCV, 30.6 +/- 2.6 cm H2O; ITPV, 22.3 +/- 4.8 cm H2O; HFO, approximately 24.3 cm H2O) were higher in PCV. Pilot histologic data showed greater interstitial hemorrhage and alveolar septal expansion in PCV than in HFO or ITPV. These data indicate that HFO, ITPV, and PCV when applied with an open-lung protective ventilatory strategy results in the same gas exchange, lung mechanics, and hemodynamic response, but pilot data indicate that lung injury may be greater with PCV.

Ventilatory drive is enhanced in male and female rats following chronic intermittent hypoxia.

PubMed

Edge, D; Skelly, J R; Bradford, A; O'Halloran, K D

2009-01-01

Obstructive sleep apnoea is characterized by chronic intermittent hypoxia (CIH) due to recurrent apnoea. We have developed a rat model of CIH, which shows evidence of impaired respiratory muscle function. In this study, we wished to characterize the ventilatory effects of CIH in conscious male and female animals. Adult male (n=14) and female (n=8) Wistar rats were used. Animals were placed in chambers daily for 8 h with free access to food and water. The gas supply to one half of the chambers alternated between air and nitrogen every 90 s, for 8 h per day, reducing ambient oxygen concentration in the chambers to 5% at the nadir (intermittent hypoxia; n=7 male, n=4 female). Air supplying the other chambers was switched every 90 s to air from a separate source, at the same flow rates, and animals in these chambers served as controls (n=7 male, n=4 female). Ventilatory measurements were made in conscious animals (typically sleeping) after 10 days using whole-body plethysmography. Normoxic ventilation was increased in both male and female CIH-treated rats compared to controls but this did not achieve statistical significance. However, ventilatory drive was increased in CIH-treated rats of both sexes as evidenced by significant increases in mean and peak inspiratory flow. Ventilatory responses to acute hypoxia (F(I)O(2) = 0.10; 6 min) and hyperoxic hypercapnia (F(I)CO(2) = 0.05; 6 min) were unaffected by CIH treatment in male and female rats (P>0.05, ANOVA). We conclude that CIH increases respiratory drive in adult rats. We speculate that this represents a form of neural plasticity that may compensate for respiratory muscle impairment that occurs in this animal model.

Quantifying the ventilatory control contribution to sleep apnoea using polysomnography.

PubMed

Terrill, Philip I; Edwards, Bradley A; Nemati, Shamim; Butler, James P; Owens, Robert L; Eckert, Danny J; White, David P; Malhotra, Atul; Wellman, Andrew; Sands, Scott A

2015-02-01

Elevated loop gain, consequent to hypersensitive ventilatory control, is a primary nonanatomical cause of obstructive sleep apnoea (OSA) but it is not possible to quantify this in the clinic. Here we provide a novel method to estimate loop gain in OSA patients using routine clinical polysomnography alone. We use the concept that spontaneous ventilatory fluctuations due to apnoeas/hypopnoeas (disturbance) result in opposing changes in ventilatory drive (response) as determined by loop gain (response/disturbance). Fitting a simple ventilatory control model (including chemical and arousal contributions to ventilatory drive) to the ventilatory pattern of OSA reveals the underlying loop gain. Following mathematical-model validation, we critically tested our method in patients with OSA by comparison with a standard (continuous positive airway pressure (CPAP) drop method), and by assessing its ability to detect the known reduction in loop gain with oxygen and acetazolamide. Our method quantified loop gain from baseline polysomnography (correlation versus CPAP-estimated loop gain: n=28; r=0.63, p<0.001), detected the known reduction in loop gain with oxygen (n=11; mean±sem change in loop gain (ΔLG) -0.23±0.08, p=0.02) and acetazolamide (n=11; ΔLG -0.20±0.06, p=0.005), and predicted the OSA response to loop gain-lowering therapy. We validated a means to quantify the ventilatory control contribution to OSA pathogenesis using clinical polysomnography, enabling identification of likely responders to therapies targeting ventilatory control. Copyright ©ERS 2015.

Quantifying the ventilatory control contribution to sleep apnoea using polysomnography

PubMed Central

Terrill, Philip I.; Edwards, Bradley A.; Nemati, Shamim; Butler, James P.; Owens, Robert L.; Eckert, Danny J.; White, David P.; Malhotra, Atul; Wellman, Andrew; Sands, Scott A.

2015-01-01

Elevated loop gain, consequent to hypersensitive ventilatory control, is a primary nonanatomical cause of obstructive sleep apnoea (OSA) but it is not possible to quantify this in the clinic. Here we provide a novel method to estimate loop gain in OSA patients using routine clinical polysomnography alone. We use the concept that spontaneous ventilatory fluctuations due to apnoeas/hypopnoeas (disturbance) result in opposing changes in ventilatory drive (response) as determined by loop gain (response/disturbance). Fitting a simple ventilatory control model (including chemical and arousal contributions to ventilatory drive) to the ventilatory pattern of OSA reveals the underlying loop gain. Following mathematical-model validation, we critically tested our method in patients with OSA by comparison with a standard (continuous positive airway pressure (CPAP) drop method), and by assessing its ability to detect the known reduction in loop gain with oxygen and acetazolamide. Our method quantified loop gain from baseline polysomnography (correlation versus CPAP-estimated loop gain: n=28; r=0.63, p<0.001), detected the known reduction in loop gain with oxygen (n=11; mean±SEM change in loop gain (ΔLG) −0.23±0.08, p=0.02) and acetazolamide (n=11; ΔLG −0.20±0.06, p=0.005), and predicted the OSA response to loop gain-lowering therapy. We validated a means to quantify the ventilatory control contribution to OSA pathogenesis using clinical polysomnography, enabling identification of likely responders to therapies targeting ventilatory control. PMID:25323235

[Respiratory symptoms and obstructive ventilatory disorder in Tunisian woman exposed to biomass].

PubMed

Kwas, H; Rahmouni, N; Zendah, I; Ghédira, H

2017-06-01

In some Tunisian cities, especially semi-urbanized, the exposure to the smoke produced during combustion of the biomass, main source of pollution of indoor air, remains prevalent among non-smoking women. To assess the relationship between exposure to biomass smoke and the presence of obstructive ventilatory disorder in the non-smoking women in semi-urban areas of Tunisia. Cross etiological study, using a questionnaire, including 140 non-smoking women responsible for cooking and/or exposed during heating by traditional means with objective measurement of their respiratory functions. We found 81 women exposed to biomass for a period > or equal to 20 hours-years and 59 unexposed women. Exposed women reported more respiratory symptoms namely exertional dyspnea and/or chronic cough than unexposed. Of the 140 women, 14 women have an FEV/FEV6 <70 % of which 13 are exposed to biomass. We found a correlation between respiratory symptoms and obstructive ventilatory disorder in exposed women. The air pollution inside the home during the traditional activities of cooking and/or heating is a respiratory risk factor for non-smoking women over the age of 30 years. Exposure to biomass smoke can cause chronic respiratory symptoms and persistent obstructive ventilatory disorder that can be consistent with COPD. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Heart rate response during a simulated Olympic boxing match is predominantly above ventilatory threshold 2: a cross sectional study

PubMed Central

de Lira, Claudio Andre Barbosa; Peixinho-Pena, Luiz Fernando; Vancini, Rodrigo Luiz; de Freitas Guina Fachina, Rafael Júlio; de Almeida, Alexandre Aparecido; Andrade, Marília dos Santos; da Silva, Antonio Carlos

2013-01-01

The present study aimed to describe heart rate (HR) responses during a simulated Olympic boxing match and examine physiological parameters of boxing athletes. Ten highly trained Olympic boxing athletes (six men and four women) performed a maximal graded exercise test on a motorized treadmill to determine maximal oxygen uptake (52.2 mL · kg−1 · min−1 ± 7.2 mL · kg−1 · min−1) and ventilatory thresholds 1 and 2. Ventilatory thresholds 1 and 2 were used to classify the intensity of exercise based on respective HR during a boxing match. In addition, oxygen uptake (V̇O2) was estimated during the match based on the HR response and the HR-V̇O2 relationship obtained from a maximal graded exercise test for each participant. On a separate day, participants performed a boxing match lasting three rounds, 2 minutes each, with a 1-minute recovery period between each round, during which HR was measured. In this context, HR and V̇O2 were above ventilatory threshold 2 during 219.8 seconds ± 67.4 seconds. There was an increase in HR and V̇O2 as a function of round (round 3 < round 2 < round 1, P < 0.0001). These findings may direct individual training programs for boxing practitioners and other athletes. PMID:24379723

Heart rate response during a simulated Olympic boxing match is predominantly above ventilatory threshold 2: a cross sectional study.

PubMed

de Lira, Claudio Andre Barbosa; Peixinho-Pena, Luiz Fernando; Vancini, Rodrigo Luiz; de Freitas Guina Fachina, Rafael Júlio; de Almeida, Alexandre Aparecido; Andrade, Marília Dos Santos; da Silva, Antonio Carlos

2013-01-01

The present study aimed to describe heart rate (HR) responses during a simulated Olympic boxing match and examine physiological parameters of boxing athletes. Ten highly trained Olympic boxing athletes (six men and four women) performed a maximal graded exercise test on a motorized treadmill to determine maximal oxygen uptake (52.2 mL · kg(-1) · min(-1) ± 7.2 mL · kg(-1) · min(-1)) and ventilatory thresholds 1 and 2. Ventilatory thresholds 1 and 2 were used to classify the intensity of exercise based on respective HR during a boxing match. In addition, oxygen uptake (V̇O2) was estimated during the match based on the HR response and the HR-V̇O2 relationship obtained from a maximal graded exercise test for each participant. On a separate day, participants performed a boxing match lasting three rounds, 2 minutes each, with a 1-minute recovery period between each round, during which HR was measured. In this context, HR and V̇O2 were above ventilatory threshold 2 during 219.8 seconds ± 67.4 seconds. There was an increase in HR and V̇O2 as a function of round (round 3 < round 2 < round 1, P < 0.0001). These findings may direct individual training programs for boxing practitioners and other athletes.

Analysis of respiratory and muscle activity by means of cross information function between ventilatory and myographic signals.

PubMed

Alonso, J F; Mañanas, M A; Hoyer, D; Topor, Z L; Bruce, E N

2004-01-01

Analysis of respiratory muscle activity is a promising technique for the study of pulmonary diseases such as obstructive sleep apnea syndrome (OSAS). Evaluation of interactions between muscles is very useful in order to determine the muscular pattern during an exercise. These interactions have already been assessed by means of different linear techniques like cross-spectrum, magnitude squared coherence or cross-correlation. The aim of this work is to evaluate interactions between respiratory and myographic signals through nonlinear analysis by means of cross mutual information function (CMIF), and finding out what information can be extracted from it. Some parameters are defined and calculated from CMIF between ventilatory and myographic signals of three respiratory muscles. Finally, differences in certain parameters were obtained between OSAS patients and healthy subjects indicating different respiratory muscle couplings.

Breathing response of the tegu lizard to 1-4% CO2 in the mouth and nose or inspired into the lungs.

PubMed

Ballam, G O

1985-12-01

This study investigated the influence on ventilation of elevated CO2 in the nasal and buccal cavities (NaBuCO2) vs the effect of elevated CO2 levels inspired into the lungs (LuCO2). Separate gas sources were used to independently alter NaBuCO2 and LuCO2. As little as 1% NaBuCO2 or LuCO2 significantly increased the pause duration between the active expiratory-inspiratory cycles. Elevated NaBuCO2 caused minor changes in tidal volume, mean inspiratory and expiratory flow, and inspiratory and expiratory durations with a significant reduction in total ventilation. Elevated LuCO2 had little effect on inspiratory or expiratory durations but unlike CO2 in the upper airways, significantly increased tidal volume and mean inspiratory and expiratory flows. This study demonstrates that the increased pause duration seen in the tegu lizard to elevated environmental CO2 is due to a receptor response in the buccal or nasal cavities and also to elevated CO2 concentrations inspired into the lungs. Sensitivity of the ventilatory responses to CO2 in the upper airways is well within a physiologically relevant range.

Image-based computational fluid dynamics in the lung: virtual reality or new clinical practice?

PubMed

Burrowes, Kelly S; De Backer, Jan; Kumar, Haribalan

2017-11-01

The development and implementation of personalized medicine is paramount to improving the efficiency and efficacy of patient care. In the respiratory system, function is largely dictated by the choreographed movement of air and blood to the gas exchange surface. The passage of air begins in the upper airways, either via the mouth or nose, and terminates at the alveolar interface, while blood flows from the heart to the alveoli and back again. Computational fluid dynamics (CFD) is a well-established tool for predicting fluid flows and pressure distributions within complex systems. Traditionally CFD has been used to aid in the effective or improved design of a system or device; however, it has become increasingly exploited in biological and medical-based applications further broadening the scope of this computational technique. In this review, we discuss the advancement in application of CFD to the respiratory system and the contributions CFD is currently making toward improving precision medicine. The key areas CFD has been applied to in the pulmonary system are in predicting fluid transport and aerosol distribution within the airways. Here we focus our discussion on fluid flows and in particular on image-based clinically focused CFD in the ventilatory system. We discuss studies spanning from the paranasal sinuses through the conducting airways down to the level of the alveolar airways. The combination of imaging and CFD is enabling improved device design in aerosol transport, improved biomarkers of lung function in clinical trials, and improved predictions and assessment of surgical interventions in the nasal sinuses. WIREs Syst Biol Med 2017, 9:e1392. doi: 10.1002/wsbm.1392 For further resources related to this article, please visit the WIREs website. © 2017 Wiley Periodicals, Inc.

Optimization behavior of brainstem respiratory neurons. A cerebral neural network model.

PubMed

Poon, C S

1991-01-01

A recent model of respiratory control suggested that the steady-state respiratory responses to CO2 and exercise may be governed by an optimal control law in the brainstem respiratory neurons. It was not certain, however, whether such complex optimization behavior could be accomplished by a realistic biological neural network. To test this hypothesis, we developed a hybrid computer-neural model in which the dynamics of the lung, brain and other tissue compartments were simulated on a digital computer. Mimicking the "controller" was a human subject who pedalled on a bicycle with varying speed (analog of ventilatory output) with a view to minimize an analog signal of the total cost of breathing (chemical and mechanical) which was computed interactively and displayed on an oscilloscope. In this manner, the visuomotor cortex served as a proxy (homolog) of the brainstem respiratory neurons in the model. Results in 4 subjects showed a linear steady-state ventilatory CO2 response to arterial PCO2 during simulated CO2 inhalation and a nearly isocapnic steady-state response during simulated exercise. Thus, neural optimization is a plausible mechanism for respiratory control during exercise and can be achieved by a neural network with cognitive computational ability without the need for an exercise stimulus.

Dynamic airway pressure-time curve profile (Stress Index): a systematic review.

PubMed

Terragni, Pierpaolo; Bussone, Guido; Mascia, Luciana

2016-01-01

The assessment of respiratory mechanics at the bedside is necessary in order to identify the most protective ventilatory strategy. Indeed in the last 20 years, adverse effects of positive ventilation to the lung structures have led to a reappraisal of the objectives of mechanical ventilation. The ventilator setting requires repeated readjustment over the period of mechanical ventilation dependency and careful respiratory monitoring to minimize the risks, preventing further injury and permitting the lung and airways healing. Among the different methods that have been proposed and validated, the analysis of dynamic P-t curve (named Stress Index, SI) represents an adequate tool available at the bedside, repeatable and, therefore, able to identify the amount of overdistension occurring in the daily clinical practice, when modifying positive end-expiratory pressure. In this review we will analyze the evidence that supports respiratory mechanics assessment at the bedside and the application of the dynamic P/t curve profile (SI) to optimize protective ventilation in patients with acute respiratory failure.

Variable Inhibition by Falling CO2 of Hypoxic Ventilatory Response in Man,

DTIC Science & Technology

1983-06-21

alkalosis which, in turn, inhibits the ventilatory response to hypoxia (4,5,11). Thus for the usual measurement of the acute ventilatory response to...rest for 20 minutes. All of the ventilatory response tests were performed with the subject breathing through a respiratory valve (Model 2700, Hans...increase ventilation because the inhibition by hypocapnic alkalosis is prevented by adding CO2 to the inspired air to maintain C02 and pH at their

Unconstrained and Noninvasive Measurement of Swimming Behavior of Small Fish Based on Ventilatory Signals

NASA Astrophysics Data System (ADS)

Kitayama, Shigehisa; Soh, Zu; Hirano, Akira; Tsuji, Toshio; Takiguchi, Noboru; Ohtake, Hisao

Ventilatory signal is a kind of bioelectric signals reflecting the ventilatory conditions of fish, and has received recent attention as an indicator for assessment of water quality, since breathing is adjusted by the respiratory center according to changes in the underwater environment surrounding the fish. The signals are thus beginning to be used in bioassay systems for water examination. Other than ventilatory conditions, swimming behavior also contains important information for water examination. The conventional bioassay systems, however, only measure either ventilatory signals or swimming behavior. This paper proposes a new unconstrained and noninvasive measurement method that is capable of conducting ventilatory signal measurement and behavioral analysis of fish at the same time. The proposed method estimates the position and the velocity of a fish in free-swimming conditions using power spectrum distribution of measured ventilatory signals from multiple electrodes. This allowed the system to avoid using a camera system which requires light sources. In order to validate estimation accuracy, the position and the velocity estimated by the proposed method were compared to those obtained from video analysis. The results confirmed that the estimated error of the fish positions was within the size of fish, and the correlation coefficient between the velocities was 0.906. The proposed method thus not only can measure the ventilatory signals, but also performs behavioral analysis as accurate as using a video camera.

Toxicological impact of waterpipe smoking and flavorings in the oral cavity and respiratory system.

PubMed

Javed, Fawad; ALHarthi, Shatha Subhi; BinShabaib, Munerah Saleh; Gajendra, Sangeeta; Romanos, Georgios E; Rahman, Irfan

2017-08-01

Waterpipe smoking (WS), an emerging trend has major health concerns. It is prevalent worldwide as a recreational activity both indoors and outdoors. The aim of this review was to assess the impact of waterpipe smoke on the oral and respiratory system (oral cavity and pulmonary tissues). A number of studies have shown that periodontal health status is compromised in waterpipe smokers when compared with nonsmokers. Some studies have associated WS with oral premalignant and malignant lesions; however, due to the poor quality of these studies, the presented outcomes should be interpreted with caution. Although cigarette smoking has been considered as a potential risk factor for dental caries; there are no studies in indexed literature that have shown an association to exist between dental caries and WS. Inhaled waterpipe smoke imposes oxidative stress and inflammatory responses and compromises the ventilatory capacity of the lungs and may lead to an increased risk of decline in lung function. WS may cause oral and pulmonary diseases, such as periodontal disease and chronic obstructive airway disease, respectively. The association between WS and development of dental caries and oral pre-cancer and their relationships with chronic airways disease requires investigations. This review discusses the current evidence of waterpipe smoke effects on the oral health and respiratory system based on basic and clinical science and provides future directions for research and regulatory science on how WS can affect the oral cavity and the respiratory/pulmonary system.

Impaired ventilatory acclimatization to hypoxia in mice lacking the immediate early gene fos B.

PubMed

Malik, Mohammad T; Peng, Ying-Jie; Kline, David D; Adhikary, Gautam; Prabhakar, Nanduri R

2005-01-15

Earlier studies on cell culture models suggested that immediate early genes (IEGs) play an important role in cellular adaptations to hypoxia. Whether IEGs are also necessary for hypoxic adaptations in intact animals is not known. In the present study we examined the potential importance of fos B, an IEG in ventilatory acclimatization to hypoxia. Experiments were performed on wild type and mutant mice lacking the fos B gene. Ventilation was monitored by whole body plethysmography in awake animals. Baseline ventilation under normoxia, and ventilatory response to acute hypoxia and hypercapnia were comparable between wild type and mutant mice. Hypobaric hypoxia (0.4 atm; 3 days) resulted in a significant elevation of baseline ventilation in wild type but not in mutant mice. Wild type mice exposed to hypobaric hypoxia manifested an enhanced hypoxic ventilatory response compared to pre-hypobaric hypoxia. In contrast, hypobaric hypoxia had no effect on the hypoxic ventilatory response in mutant mice. Hypercapnic ventilatory responses, however, were unaffected by hypobaric hypoxia in both groups of mice. These results suggest that the fos B, an immediate early gene, plays an important role in ventilatory acclimatization to hypoxia in mice.

Role of tachykinins in ozone-induced acute lung injury in guinea pigs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tepper, J.S.; Costa, D.L.; Fitzgerald, S.

To examine the hypothesis that the acute reversible changes caused by ozone (O3) exposure are mediated by tachykinin release, guinea pigs were depleted of tachykinins by use of repeated capsaicin (CAP) injections before O3 exposure in an attempt to prevent O3-induced functional changes. Unexpectedly, CAP pretreatment caused divergent results in the functional responses to O3. Ventilatory measurements obtained from CAP-pretreated O3-exposed (CAP-O3) animals were exacerbated rather than diminished compared with the effects of O3 alone. Similarly, lavage fluid protein accumulation was enhanced in the CAP-O3 group compared with the O3-exposed group. In better agreement with our initial hypothesis, the CAP-O3more » group was less responsive than the O3-exposed animals to histamine aerosol challenge. Additionally, Evans blue dye accumulation, a hallmark of tachykinin release, was increased in O3-exposed animals and was partially blocked in the CAP-O3 group. These data suggest that tachykinin-containing sensory fibers are unlikely to mediate the acute effects of O3 exposure on tidal breathing and lavage fluid protein accumulation but may play a role in causing post-O3 airway hyperreactivity and protein extravasation into the trachea.« less

REAL-TIME MONITORING FOR TOXICITY CAUSED BY HARMFUL ALGAL BLOOMS AND OTHER WATER QUALITY PERTURBATIONS

EPA Science Inventory

This project, sponsored by EPA's Environmental Monitoring for Public Access and Community Tracking (EMPACT) program, evaluated the ability of an automated biological monitoring system that measures fish ventilatory responses (ventilatory rate, ventilatory depth, and cough rate) t...

"Optimal" application of ventilatory assist in Cheyne-Stokes respiration: a simulation study.

PubMed

Khoo, M C; Benser, M E

2005-01-01

Although a variety of ventilator therapies have been employed to treat Cheyne-Stokes respiration (CSR), these modalities do not completely eliminate CSR. As well, most current strategies require that ventilatory assist be provided continuously. We used a computer model of the respiratory control system to determine whether a ventilatory assist strategy could be found that would substantially reduce the severity of CSR while minimizing the application of positive airway pressure. We assessed the effects of different levels of ventilatory assist applied during breaths that fell below selected hypopneic thresholds. These could be applied during the descending, ascending, or both phases of the CSR cycle. We found that ventilatory augmentation equal to 30-40% of eupneic drive, applied whenever ventilation fell below 70% of the eupneic level during the ascending or descending-and-ascending phases of CSR led to the greatest regularization of breathing with minimal ventilator intervention. Application of ventilatory assist during the descending phase produced little effect.

Influence of sympathoexcitation at high altitude on cerebrovascular function and ventilatory control in humans.

PubMed

Ainslie, P N; Lucas, S J E; Fan, J-L; Thomas, K N; Cotter, J D; Tzeng, Y C; Burgess, Keith R

2012-10-01

We sought to determine the influence of sympathoexcitation on dynamic cerebral autoregulation (CA), cerebrovascular reactivity, and ventilatory control in humans at high altitude (HA). At sea level (SL) and following 3-10 days at HA (5,050 m), we measured arterial blood gases, ventilation, arterial pressure, and middle cerebral blood velocity (MCAv) before and after combined α- and β-adrenergic blockade. Dynamic CA was quantified using transfer function analysis. Cerebrovascular reactivity was assessed using hypocapnia and hyperoxic hypercapnia. Ventilatory control was assessed from the hypercapnia and during isocapnic hypoxia. Arterial Pco(2) and ventilation and its control were unaltered following blockade at both SL and HA. At HA, mean arterial pressure (MAP) was elevated (P < 0.01 vs. SL), but MCAv remained unchanged. Blockade reduced MAP more at HA than at SL (26 vs. 15%, P = 0.048). At HA, gain and coherence in the very-low-frequency (VLF) range (0.02-0.07 Hz) increased, and phase lead was reduced (all P < 0.05 vs. SL). Following blockade at SL, coherence was unchanged, whereas VLF phase lead was reduced (-40 ± 23%; P < 0.01). In contrast, blockade at HA reduced low-frequency coherence (-26 ± 20%; P = 0.01 vs. baseline) and elevated VLF phase lead (by 177 ± 238%; P < 0.01 vs. baseline), fully restoring these parameters back to SL values. Irrespective of this elevation in VLF gain at HA (P < 0.01), blockade increased it comparably at SL and HA (∼43-68%; P < 0.01). Despite elevations in MCAv reactivity to hypercapnia at HA, blockade reduced (P < 0.05) it comparably at SL and HA, effects we attributed to the hypotension and/or abolition of the hypercapnic-induced increase in MAP. With the exception of dynamic CA, we provide evidence of a redundant role of sympathetic nerve activity as a direct mechanism underlying changes in cerebrovascular reactivity and ventilatory control following partial acclimatization to HA. These findings have implications for our understanding of CBF function in the context of pathologies associated with sympathoexcitation and hypoxemia.

RNASeq-derived transcriptome comparisons reveal neuromodulatory deficiency in the CO2 insensitive brown Norway rat

PubMed Central

Puissant, Madeleine M; Echert, Ashley E; Yang, Chun; Mouradian, Gary C; Novotny, Tyler; Liu, Pengyuan; Liang, Mingyu; Hodges, Matthew R

2015-01-01

Raphé-derived serotonin (5-HT) and thyrotropin-releasing hormone (TRH) play important roles in fundamental, homeostatic control systems such as breathing and specifically the ventilatory CO2 chemoreflex. Brown Norway (BN) rats exhibit an inherent and severe ventilatory insensitivity to hypercapnia but also exhibit relatively normal ventilation at rest and during other conditions, similar to multiple genetic models of 5-HT system dysfunction in mice. Herein, we tested the hypothesis that the ventilatory insensitivity to hypercapnia in BN rats is due to altered raphé gene expression and the consequent deficiencies in raphé-derived neuromodulators such as TRH. Medullary raphé transcriptome comparisons revealed lower expression of multiple 5-HT neuron-specific genes in BN compared to control Dahl salt-sensitive rats, predictive of reduced central nervous system monoamines by bioinformatics analyses and confirmed by high-performance liquid chromatography measurements. In particular, raphé Trh mRNA and peptide levels were significantly reduced in BN rats, and injections of the stable TRH analogue Taltirelin (TAL) stimulated breathing dose-dependently, with greater effects in BN versus control Sprague–Dawley rats. Importantly, TAL also effectively normalized the ventilatory CO2 chemoreflex in BN rats, but TAL did not affect CO2 sensitivity in control Sprague–Dawley rats. These data establish a molecular basis of the neuromodulatory deficiency in BN rats, and further suggest an important functional role for TRH signalling in the mammalian CO2 chemoreflex. PMID:25630262

Prefrontal cortex haemodynamics and affective responses during exercise: a multi-channel near infrared spectroscopy study.

PubMed

Tempest, Gavin D; Eston, Roger G; Parfitt, Gaynor

2014-01-01

The dose-response effects of the intensity of exercise upon the potential regulation (through top-down processes) of affective (pleasure-displeasure) responses in the prefrontal cortex during an incremental exercise protocol have not been explored. This study examined the functional capacity of the prefrontal cortex (reflected by haemodynamics using near infrared spectroscopy) and affective responses during exercise at different intensities. Participants completed an incremental cycling exercise test to exhaustion. Changes (Δ) in oxygenation (O2Hb), deoxygenation (HHb), blood volume (tHb) and haemoglobin difference (HbDiff) were measured from bilateral dorsal and ventral prefrontal areas. Affective responses were measured every minute during exercise. Data were extracted at intensities standardised to: below ventilatory threshold, at ventilatory threshold, respiratory compensation point and the end of exercise. During exercise at intensities from ventilatory threshold to respiratory compensation point, ΔO2Hb, ΔHbDiff and ΔtHb were greater in mostly ventral than dorsal regions. From the respiratory compensation point to the end of exercise, ΔO2Hb remained stable and ΔHbDiff declined in dorsal regions. As the intensity increased above the ventilatory threshold, inverse associations between affective responses and oxygenation in (a) all regions of the left hemisphere and (b) lateral (dorsal and ventral) regions followed by the midline (ventral) region in the right hemisphere were observed. Differential activation patterns occur within the prefrontal cortex and are associated with affective responses during cycling exercise.

Prefrontal Cortex Haemodynamics and Affective Responses during Exercise: A Multi-Channel Near Infrared Spectroscopy Study

PubMed Central

Tempest, Gavin D.; Eston, Roger G.; Parfitt, Gaynor

2014-01-01

The dose-response effects of the intensity of exercise upon the potential regulation (through top-down processes) of affective (pleasure-displeasure) responses in the prefrontal cortex during an incremental exercise protocol have not been explored. This study examined the functional capacity of the prefrontal cortex (reflected by haemodynamics using near infrared spectroscopy) and affective responses during exercise at different intensities. Participants completed an incremental cycling exercise test to exhaustion. Changes (Δ) in oxygenation (O2Hb), deoxygenation (HHb), blood volume (tHb) and haemoglobin difference (HbDiff) were measured from bilateral dorsal and ventral prefrontal areas. Affective responses were measured every minute during exercise. Data were extracted at intensities standardised to: below ventilatory threshold, at ventilatory threshold, respiratory compensation point and the end of exercise. During exercise at intensities from ventilatory threshold to respiratory compensation point, ΔO2Hb, ΔHbDiff and ΔtHb were greater in mostly ventral than dorsal regions. From the respiratory compensation point to the end of exercise, ΔO2Hb remained stable and ΔHbDiff declined in dorsal regions. As the intensity increased above the ventilatory threshold, inverse associations between affective responses and oxygenation in (a) all regions of the left hemisphere and (b) lateral (dorsal and ventral) regions followed by the midline (ventral) region in the right hemisphere were observed. Differential activation patterns occur within the prefrontal cortex and are associated with affective responses during cycling exercise. PMID:24788166

Substance P-induced respiratory excitation is blunted by delta-receptor specific opioids in the rat medulla oblongata.

PubMed

Chen, Z; Hedner, J; Hedner, T

1996-06-01

The effects of substance P (SP) and the naturally occurring met-enkephalin and the synthetic mu-specific opioid agonist, DAGO (Tyr-D-Ala-Gly-N-Methy-Phe-Gly-ol) and the delta-specific opioid agonist DADL (Tyr-D-Ala-Gly-Phe-D-Leu) on basal ventilation were investigated in halothane-anaesthetized rats. Local injections of SP (0.75-1.5 nmol) in the ventrolateral medulla oblongata (VLM), e.g. nucleus paragigantocellularis, and nucleus reticularis lateralis increased ventilation because of an elevation of tidal volume. Met-enkephalin induced a short-lasting ventilatory depression mainly because of a depression of tidal volume. Activation of delta- and mu-opioid receptors in the VLM by local application of DADL and DAGO, respectively, induced ventilatory depression, which was later in onset and more long-lasting. Local administration of met-enkephalin into the VLM also produced a long-lasting inhibition of the SP-induced ventilatory excitation. A similar blockade of the SP-induced excitatory ventilatory response could be elicited by DADL but not by DAGO. This antagonistic effect was attenuated by local application of the delta-opioid receptor antagonist ICI 154. 129. We conclude that the naturally occurring met-enkephalin as well as synthetic mu- and delta-specific enkephalin analogues (DAGO and DADL, respectively) in VLM depress basal ventilation by an effect on inspiratory drive. There is a functional antagonism between activation of delta-opioid receptors and SP receptors into the VLM in respect to respiratory regulation.

Guinea Pig Oxygen-Sensing and Carotid Body Functional Properties

PubMed Central

Gonzalez-Obeso, Elvira; Docio, Inmaculada; Olea, Elena; Cogolludo, Angel; Obeso, Ana; Rocher, Asuncion; Gomez-Niño, Angela

2017-01-01

Mammals have developed different mechanisms to maintain oxygen supply to cells in response to hypoxia. One of those mechanisms, the carotid body (CB) chemoreceptors, is able to detect physiological hypoxia and generate homeostatic reflex responses, mainly ventilatory and cardiovascular. It has been reported that guinea pigs, originally from the Andes, have a reduced ventilatory response to hypoxia compared to other mammals, implying that CB are not completely functional, which has been related to genetically/epigenetically determined poor hypoxia-driven CB reflex. This study was performed to check the guinea pig CB response to hypoxia compared to the well-known rat hypoxic response. These experiments have explored ventilatory parameters breathing different gases mixtures, cardiovascular responses to acute hypoxia, in vitro CB response to hypoxia and other stimuli and isolated guinea pig chemoreceptor cells properties. Our findings show that guinea pigs are hypotensive and have lower arterial pO2 than rats, probably related to a low sympathetic tone and high hemoglobin affinity. Those characteristics could represent a higher tolerance to hypoxic environment than other rodents. We also find that although CB are hypo-functional not showing chronic hypoxia sensitization, a small percentage of isolated carotid body chemoreceptor cells contain tyrosine hydroxylase enzyme and voltage-dependent K+ currents and therefore can be depolarized. However hypoxia does not modify intracellular Ca2+ levels or catecholamine secretion. Guinea pigs are able to hyperventilate only in response to intense acute hypoxic stimulus, but hypercapnic response is similar to rats. Whether other brain areas are also activated by hypoxia in guinea pigs remains to be studied. PMID:28533756

Guinea Pig Oxygen-Sensing and Carotid Body Functional Properties.

PubMed

Gonzalez-Obeso, Elvira; Docio, Inmaculada; Olea, Elena; Cogolludo, Angel; Obeso, Ana; Rocher, Asuncion; Gomez-Niño, Angela

2017-01-01

Mammals have developed different mechanisms to maintain oxygen supply to cells in response to hypoxia. One of those mechanisms, the carotid body (CB) chemoreceptors, is able to detect physiological hypoxia and generate homeostatic reflex responses, mainly ventilatory and cardiovascular. It has been reported that guinea pigs, originally from the Andes, have a reduced ventilatory response to hypoxia compared to other mammals, implying that CB are not completely functional, which has been related to genetically/epigenetically determined poor hypoxia-driven CB reflex. This study was performed to check the guinea pig CB response to hypoxia compared to the well-known rat hypoxic response. These experiments have explored ventilatory parameters breathing different gases mixtures, cardiovascular responses to acute hypoxia, in vitro CB response to hypoxia and other stimuli and isolated guinea pig chemoreceptor cells properties. Our findings show that guinea pigs are hypotensive and have lower arterial pO 2 than rats, probably related to a low sympathetic tone and high hemoglobin affinity. Those characteristics could represent a higher tolerance to hypoxic environment than other rodents. We also find that although CB are hypo-functional not showing chronic hypoxia sensitization, a small percentage of isolated carotid body chemoreceptor cells contain tyrosine hydroxylase enzyme and voltage-dependent K + currents and therefore can be depolarized. However hypoxia does not modify intracellular Ca 2+ levels or catecholamine secretion. Guinea pigs are able to hyperventilate only in response to intense acute hypoxic stimulus, but hypercapnic response is similar to rats. Whether other brain areas are also activated by hypoxia in guinea pigs remains to be studied.

OBESITY: CHALLENGES TO VENTILATORY CONTROL DURING EXERCISE A BRIEF REVIEW

PubMed Central

Babb, Tony G.

2013-01-01

Obesity is a national health issue in the US. Among the many physiological changes induced by obesity, it also presents a unique challenge to ventilatory control during exercise due to increased metabolic demand of moving larger limbs, increased work of breathing due to extra weight on the chest wall, and changes in breathing mechanics. These challenges to ventilatory control in obesity can be inconspicuous or overt among obese adults but for the most part adaptation of ventilatory control during exercise in obesity appears remarkably unnoticed in the majority of obese people. In this brief review, the changes to ventilatory control required for maintaining normal ventilation during exercise will be examined, especially the interaction between respiratory neural drive and ventilation. Also, gaps in our current knowledge will be discussed. PMID:23707540

20 CFR 404.1519n - Informing the medical source of examination scheduling, report content, and signature requirements.

Code of Federal Regulations, 2010 CFR

2010-04-01

... ventilatory function tests, treadmill exercise tests, or audiological tests. The medical report must be... other abnormalities or lack thereof reported or found during examination or laboratory testing; (4) The...

Estimates of restrictive ventilatory defect in the mining industry. Considerations for epidemiological investigations: a cross-sectional study

PubMed Central

Odo, Nnaemeka U; Mandel, Jeffrey H; Perlman, David M; Alexander, Bruce H; Scanlon, Paul D

2013-01-01

Objectives (1) To assess the impact of American Thoracic Society and European Respiratory Society (ATS/ERS) ‘acceptability’ and ‘usability’ criteria for spirometry on the estimates of restrictive ventilatory defect in a population of taconite miners. (2) To compare estimates of restrictive ventilatory defect with three different pulmonary function tests (spirometry, alveolar volume (VA) and diffusing capacity (DL,CO)). (3) To assess the role of population characteristics on these estimates. Design Cross-sectional study. Setting Current and former workers in six current taconite mining operations of northeastern Minnesota were surveyed. Participants We attempted to enrol 3313 participants. Of these, 1353 responded while 1188 current and former workers fully participated in the survey and 1084 performed complete pulmonary function testing and were assessed. Primary and secondary outcome measures We applied ATS/ERS acceptability criteria for all tests and categorised participants into groups according to whether they fully met, partially met or did not meet acceptability criteria for spirometry. Obstruction and restriction were defined utilising the lower limit of normal for all tests. When using VA, restriction was identified after excluding obstruction. Results Only 519 (47.9%) tests fully met ATS/ERS spirometry acceptability criteria. Within this group, 5% had obstruction and 6%, restriction on spirometry. In contrast, among all participants (N=1084), 16.8% had obstruction, while 4.5% had restriction. VA showed similar results in all groups after obstruction was excluded. Impaired gas transfer (reduced DL,CO) was identified in less than 50% of restriction identified by either spirometry or VA. Body mass index (BMI) was significantly related to spirometric restriction in all groups. Conclusions Population estimates of restriction using spirometry or VA varied by spirometric acceptability criteria. Other factors identified as important considerations in the estimation of restrictive ventilatory defect included increased BMI and gas transfer impairment in a relatively smaller proportion of those with spirometric restriction. These insights are important when interpreting population-based physiological data in occupational settings. PMID:23869101

Estimates of restrictive ventilatory defect in the mining industry. Considerations for epidemiological investigations: a cross-sectional study.

PubMed

Odo, Nnaemeka U; Mandel, Jeffrey H; Perlman, David M; Alexander, Bruce H; Scanlon, Paul D

2013-01-01

(1) To assess the impact of American Thoracic Society and European Respiratory Society (ATS/ERS) 'acceptability' and 'usability' criteria for spirometry on the estimates of restrictive ventilatory defect in a population of taconite miners. (2) To compare estimates of restrictive ventilatory defect with three different pulmonary function tests (spirometry, alveolar volume (VA) and diffusing capacity (DL,CO)). (3) To assess the role of population characteristics on these estimates. Cross-sectional study. Current and former workers in six current taconite mining operations of northeastern Minnesota were surveyed. We attempted to enrol 3313 participants. Of these, 1353 responded while 1188 current and former workers fully participated in the survey and 1084 performed complete pulmonary function testing and were assessed. We applied ATS/ERS acceptability criteria for all tests and categorised participants into groups according to whether they fully met, partially met or did not meet acceptability criteria for spirometry. Obstruction and restriction were defined utilising the lower limit of normal for all tests. When using VA, restriction was identified after excluding obstruction. Only 519 (47.9%) tests fully met ATS/ERS spirometry acceptability criteria. Within this group, 5% had obstruction and 6%, restriction on spirometry. In contrast, among all participants (N=1084), 16.8% had obstruction, while 4.5% had restriction. VA showed similar results in all groups after obstruction was excluded. Impaired gas transfer (reduced DL,CO) was identified in less than 50% of restriction identified by either spirometry or VA. Body mass index (BMI) was significantly related to spirometric restriction in all groups. Population estimates of restriction using spirometry or VA varied by spirometric acceptability criteria. Other factors identified as important considerations in the estimation of restrictive ventilatory defect included increased BMI and gas transfer impairment in a relatively smaller proportion of those with spirometric restriction. These insights are important when interpreting population-based physiological data in occupational settings.

Changes in respiratory control after three hours of isocapnic hypoxia in humans

PubMed Central

Mahamed, Safraaz; Cunningham, David A; Duffin, James

2003-01-01

Despite the obvious role of hypoxia in eliciting respiratory acclimatisation in humans, the function of the peripheral chemoreflex is uncertain. We investigated this uncertainty using 3 h of isocapnic hypoxia as a stimulus (end-tidal PCO2, 0.5–1.0 mmHg above eucapnia; end-tidal PO2, 50 mmHg), hypothesising that this stimulus would induce an enhancement of the peripheral chemoreflex ventilatory response to hypoxia. Current evidence conflicts as to whether this enhancement is mediated by an increase in the sensitivity or a decrease in the threshold of the peripheral chemoreflex ventilatory response to carbon dioxide. Employing a modified rebreathing technique to assess chemoreflex function, we found evidence of the latter in nine healthy volunteers (six male, three female). Testing consisted of pairs of isoxic rebreathing tests at high and low levels of oxygen, performed before, immediately after and 1 h after a 3 h isocapnic hypoxic exposure. No parameters changed significantly in the high-oxygen rebreathing tests. In the low-oxygen rebreathing tests there were no changes in non-chemoreflex ventilatory drives, or in the sensitivity to carbon dioxide, but the carbon dioxide response threshold decreased (≈1.5 mmHg) immediately after exposure, and the decrease persisted for 1 h (one-way repeated-measures ANOVA; P < 0.05). We repeated the protocol in five of the original nine volunteers, but this time exposing them to isocapnic normoxia. No trends or significant changes were observed in any of the rebreathing test parameters. These findings demonstrate that in the earliest stages of acclimatisation, there is a decrease in the threshold of the peripheral chemoreflex response to carbon dioxide, which persists for at least 1 h after the return to normoxia. We suggest that ventilatory acclimatisation to hypoxia results from this decreased threshold, reflecting an increase in the activity of the peripheral chemoreflex. PMID:12562969

The gross morphology and histochemistry of respiratory muscles in bottlenose dolphins, Tursiops truncatus.

PubMed

Cotten, Pamela B; Piscitelli, Marina A; McLellan, William A; Rommel, Sentiel A; Dearolf, Jennifer L; Pabst, D Ann

2008-12-01

Most mammals possess stamina because their locomotor and respiratory (i.e., ventilatory) systems are mechanically coupled. These systems are decoupled, however, in bottlenose dolphins (Tursiops truncatus) as they swim on a breath hold. Locomotion and ventilation are coupled only during their brief surfacing event, when they respire explosively (up to 90% of total lung volume in approximately 0.3 s) (Ridgway et al. 1969 Science 166:1651-1654). The predominantly slow-twitch fiber profile of their diaphragm (Dearolf 2003 J Morphol 256:79-88) suggests that this muscle does not likely power their rapid ventilatory event. Based on Bramble's (1989 Amer Zool 29:171-186) biomechanical model of locomotor-respiratory coupling in galloping mammals, it was hypothesized that locomotor muscles function to power ventilation in bottlenose dolphins. It was further hypothesized that these muscles would be composed predominantly of fast-twitch fibers to facilitate the bottlenose dolphin's rapid ventilation. The gross morphology of craniocervical (scalenus, sternocephalicus, sternohyoid), thoracic (intercostals, transverse thoracis), and lumbopelvic (hypaxialis, rectus abdominis, abdominal obliques) muscles (n = 7) and the fiber-type profiles (n = 6) of selected muscles (scalenus, sternocephalicus, sternohyoid, rectus abdominis) of bottlenose dolphins were investigated. Physical manipulations of excised thoracic units were carried out to investigate potential actions of these muscles. Results suggest that the craniocervical muscles act to draw the sternum and associated ribs craniodorsally, which flares the ribs laterally, and increases the thoracic cavity volume required for inspiration. The lumbopelvic muscles act to draw the sternum and caudal ribs caudally, which decreases the volumes of the thoracic and abdominal cavities required for expiration. All muscles investigated were composed predominantly of fast-twitch fibers (range 61-88% by area) and appear histochemically poised for rapid contraction. These combined results suggest that dolphins utilize muscles, similar to those used by galloping mammals, to power their explosive ventilation. (c) 2008 Wiley-Liss, Inc.

Sleep and Respiration in Microgravity

NASA Technical Reports Server (NTRS)

West, John B.; Elliott, Ann R.; Prisk, G. Kim; Paiva, Manuel

2003-01-01

Sleep is often reported to be of poor quality in microgravity, and studies on the ground have shown a strong relationship between sleep-disordered breathing and sleep disruption. During the 16-day Neurolab mission, we studied the influence of possible changes in respiratory function on sleep by performing comprehensive sleep recordings on the payload crew on four nights during the mission. In addition, we measured the changes in the ventilatory response to low oxygen and high carbon dioxide in the same subjects during the day, hypothesizing that changes in ventilatory control might affect respiration during sleep. Microgravity caused a large reduction in the ventilatory response to reduced oxygen. This is likely the result of an increase in blood pressure at the peripheral chemoreceptors in the neck that occurs when the normally present hydrostatic pressure gradient between the heart and upper body is abolished. This reduction was similar to that seen when the subjects were placed acutely in the supine position in one-G. In sharp contrast to low oxygen, the ventilatory response to elevated carbon dioxide was unaltered by microgravity or the supine position. Because of the similarities of the findings in microgravity and the supine position, it is unlikely that changes in ventilatory control alter respiration during sleep in microgravity. During sleep on the ground, there were a small number of apneas (cessation of breathing) and hypopneas (reduced breathing) in these normal subjects. During sleep in microgravity, there was a reduction in the number of apneas and hypopneas per hour compared to preflight. Obstructive apneas virtually disappeared in microgravity, suggesting that the removal of gravity prevents the collapse of upper airways during sleep. Arousals from sleep were reduced in microgravity compared to preflight, and virtually all of this reduction was as a result of a reduction in the number of arousals from apneas and hypopneas. We conclude that any sleep disruption in microgravity is not the result of respiratory factors.

Cardiorespiratory Coupling: Common Rhythms in Cardiac, Sympathetic, and Respiratory Activities

PubMed Central

Dick, Thomas E.; Hsieh, Yee-Hsee; Dhingra, Rishi R.; Baekey, David M.; Galán, Roberto F.; Wehrwein, Erica; Morris, Kendall F.

2014-01-01

Cardiorespiratory coupling is an encompassing term describing more than the well-recognized influences of respiration on heart rate and blood pressure. Our data indicate that cardiorespiratory coupling reflects a reciprocal interaction between autonomic and respiratory control systems, and the cardiovascular system modulates the ventilatory pattern as well. For example, cardioventilatory coupling refers to the influence of heart beats and arterial pulse pressure on respiration and is the tendency for the next inspiration to start at a preferred latency after the last heart beat in expiration. Multiple complementary, well-described mechanisms mediate respiration’s influence on cardiovascular function, whereas mechanisms mediating the cardiovascular system’s influence on respiration may only be through the baroreceptors but are just being identified. Our review will describe a differential effect of conditioning rats with either chronic intermittent or sustained hypoxia on sympathetic nerve activity but also on ventilatory pattern variability. Both intermittent and sustained hypoxia increase sympathetic nerve activity after 2 weeks but affect sympatho-respiratory coupling differentially. Intermittent hypoxia enhances sympatho-respiratory coupling, which is associated with low variability in the ventilatory pattern. In contrast, after constant hypobaric hypoxia, 1-to-1 coupling between bursts of sympathetic and phrenic nerve activity is replaced by 2-to-3 coupling. This change in coupling pattern is associated with increased variability of the ventilatory pattern. After baro-denervating hypobaric hypoxic-conditioned rats, splanchnic sympathetic nerve activity becomes tonic (distinct bursts are absent) with decreases during phrenic nerve bursts and ventilatory pattern becomes regular. Thus, conditioning rats to either intermittent or sustained hypoxia accentuates the reciprocal nature of cardiorespiratory coupling. Finally, identifying a compelling physiologic purpose for cardiorespiratory coupling is the biggest barrier for recognizing its significance. Cardiorespiratory coupling has only a small effect on the efficiency of gas exchange; rather, we propose that cardiorespiratory control system may act as weakly coupled oscillator to maintain rhythms within a bounded variability. PMID:24746049

Assessment of ventilatory thresholds during graded and maximal exercise test using time varying analysis of respiratory sinus arrhythmia.

PubMed

Blain, G; Meste, O; Bouchard, T; Bermon, S

2005-07-01

To test whether ventilatory thresholds, measured during an exercise test, could be assessed using time varying analysis of respiratory sinus arrhythmia frequency (f(RSA)). Fourteen sedentary subjects and 12 endurance athletes performed a graded and maximal exercise test on a cycle ergometer: initial load 75 W (sedentary subjects) and 150 W (athletes), increments 37.5 W/2 min. f(RSA) was extracted from heart period series using an evolutive model. First (T(V1)) and second (T(V2)) ventilatory thresholds were determined from the time course curves of ventilation and ventilatory equivalents for O(2) and CO(2). f(RSA) was accurately extracted from all recordings and positively correlated to respiratory frequency (r = 0.96 (0.03), p<0.01). In 21 of the 26 subjects, two successive non-linear increases were determined in f(RSA), defining the first (T(RSA1)) and second (T(RSA2)) f(RSA) thresholds. When expressed as a function of power, T(RSA1) and T(RSA2) were not significantly different from and closely linked to T(V1) (r = 0.99, p<0.001) and T(V2) (r = 0.99, p<0.001), respectively. In the five remaining subjects, only one non-linear increase was observed close to T(V2). Significant differences (p<0.04) were found between athlete and sedentary groups when T(RSA1) and T(RSA2) were expressed in terms of absolute and relative power and percentage of maximal aerobic power. In the sedentary group, T(RSA1) and T(RSA2) were 150.3 (18.7) W and 198.3 (28.8) W, respectively, whereas in the athlete group T(RSA1) and T(RSA2) were 247.3 (32.8) W and 316.0 (28.8) W, respectively. Dynamic analysis of f(RSA) provides a useful tool for identifying ventilatory thresholds during graded and maximal exercise test in sedentary subjects and athletes.

Assessment of ventilatory thresholds during graded and maximal exercise test using time varying analysis of respiratory sinus arrhythmia

PubMed Central

Blain, G; Meste, O; Bouchard, T; Bermon, S; Segura, R.

2005-01-01

Objective: To test whether ventilatory thresholds, measured during an exercise test, could be assessed using time varying analysis of respiratory sinus arrhythmia frequency (fRSA). Methods: Fourteen sedentary subjects and 12 endurance athletes performed a graded and maximal exercise test on a cycle ergometer: initial load 75 W (sedentary subjects) and 150 W (athletes), increments 37.5 W/2 min. fRSA was extracted from heart period series using an evolutive model. First (TV1) and second (TV2) ventilatory thresholds were determined from the time course curves of ventilation and ventilatory equivalents for O2 and CO2. Results: fRSA was accurately extracted from all recordings and positively correlated to respiratory frequency (r = 0.96 (0.03), p<0.01). In 21 of the 26 subjects, two successive non-linear increases were determined in fRSA, defining the first (TRSA1) and second (TRSA2) fRSA thresholds. When expressed as a function of power, TRSA1 and TRSA2 were not significantly different from and closely linked to TV1 (r = 0.99, p<0.001) and TV2 (r = 0.99, p<0.001), respectively. In the five remaining subjects, only one non-linear increase was observed close to TV2. Significant differences (p<0.04) were found between athlete and sedentary groups when TRSA1 and TRSA2 were expressed in terms of absolute and relative power and percentage of maximal aerobic power. In the sedentary group, TRSA1 and TRSA2 were 150.3 (18.7) W and 198.3 (28.8) W, respectively, whereas in the athlete group TRSA1 and TRSA2 were 247.3 (32.8) W and 316.0 (28.8) W, respectively. Conclusions: Dynamic analysis of fRSA provides a useful tool for identifying ventilatory thresholds during graded and maximal exercise test in sedentary subjects and athletes. PMID:15976169

Ventilatory responses to hypercapnia and hypoxia after 6 h passive hyperventilation in humans

PubMed Central

Ren, Xiaohui; Robbins, Peter A

1999-01-01

Acute exposure to hypoxia stimulates ventilation and induces hypocapnia. Long-term exposure to hypoxia generates changes in respiratory control known as ventilatory acclimatization to hypoxia. The object of this study was to investigate the degree to which the hyperventilation and hypocapnia can induce the changes known as ventilatory acclimatization to hypoxia, in the absence of the primary hypoxic stimulus itself.Three 6 h protocols were each performed on twelve healthy volunteers: (1) passive hypocapnic hyperventilation, with end-tidal CO2 pressure (PET,CO2) held 10 Torr below the eupnoeic value; (2) passive eucapnic hyperventilation, with PET,CO2 maintained eucapnic; (3) control.Ventilatory responses to acute hypercapnia and hypoxia were assessed before and half an hour after each protocol.The presence of prior hypocapnia, but not prior hyperventilation, caused a reduction in air-breathing PET,CO2 (P < 0·05, ANOVA), and a leftwards shift of the ventilatory response to hypercapnia (P < 0·05). The presence of prior hyperventilation, but not prior hypocapnia, caused an increase in the ventilatory sensitivity to CO2 (P < 0·05). No significant effects of any protocol were detected on the ventilatory sensitivity to hypoxia.We conclude that following 6 h of passive hyperventilation: (i) the left shift of the VE-PET,CO2 relationship is due to alkalosis and not to hyperventilation; (ii) the increase in slope of the VE-PET,CO2 relationship is due to the hyperventilation and not the alkalosis; and (iii) ventilatory sensitivity to hypoxia is unaltered. PMID:9882758

A critical role of acute bronchoconstriction in the mortality associated with high-dose sarin inhalation: Effects of epinephrine and oxygen therapies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gundavarapu, Sravanthi; Zhuang, Jianguo; Barrett, Edward G.

Sarin is an organophosphate nerve agent that is among the most lethal chemical toxins known to mankind. Because of its vaporization properties and ease and low cost of production, sarin is the nerve agent with a strong potential for use by terrorists and rouge nations. The primary route of sarin exposure is through inhalation and, depending on the dose, sarin leads to acute respiratory failure and death. The mechanism(s) of sarin-induced respiratory failure is poorly understood. Sarin irreversibly inhibits acetylcholine esterase, leading to excessive synaptic levels of acetylcholine and, we have previously shown that sarin causes marked ventilatory changes includingmore » weakened response to hypoxia. We now show that LD{sub 50} sarin inhalation causes severe bronchoconstriction in rats, leading to airway resistance, increased hypoxia-induced factor-1α, and severe lung epithelium injury. Transferring animals into 60% oxygen chambers after sarin exposure improved the survival from about 50% to 75% at 24 h; however, many animals died within hours after removal from the oxygen chambers. On the other hand, if LD{sub 50} sarin-exposed animals were administered the bronchodilator epinephrine, > 90% of the animals survived. Moreover, while both epinephrine and oxygen treatments moderated cardiorespiratory parameters, the proinflammatory cytokine surge, and elevated expression of hypoxia-induced factor-1α, only epinephrine consistently reduced the sarin-induced bronchoconstriction. These data suggest that severe bronchoconstriction is a critical factor in the mortality induced by LD{sub 50} sarin inhalation, and epinephrine may limit the ventilatory, inflammatory, and lethal effects of sarin. - Highlights: • Inhalation exposure of rats to LD{sub 50} sarin causes death through respiratory failure. • Severe bronchoconstriction is the major cause of sarin-induced respiratory failure. • Transfer of sarin exposed rats to 60% oxygen improves the mortality temporarily. • Epinephrine improves bronchoconstriction and mortality in LD{sub 50} sarin-exposed rats. • Both epinephrine and oxygen moderate the sarin-induced lung inflammatory response.« less

Adult venovenous extracorporeal membrane oxygenation for severe respiratory failure: Current status and future perspectives.

PubMed

Sen, Ayan; Callisen, Hannelisa E; Alwardt, Cory M; Larson, Joel S; Lowell, Amelia A; Libricz, Stacy L; Tarwade, Pritee; Patel, Bhavesh M; Ramakrishna, Harish

2016-01-01

Extracorporeal membrane oxygenation (ECMO) for severe acute respiratory failure was proposed more than 40 years ago. Despite the publication of the ARDSNet study and adoption of lung protective ventilation, the mortality for acute respiratory failure due to acute respiratory distress syndrome has continued to remain high. This technology has evolved over the past couple of decades and has been noted to be safe and successful, especially during the worldwide H1N1 influenza pandemic with good survival rates. The primary indications for ECMO in acute respiratory failure include severe refractory hypoxemic and hypercarbic respiratory failure in spite of maximum lung protective ventilatory support. Various triage criteria have been described and published. Contraindications exist when application of ECMO may be futile or technically impossible. Knowledge and appreciation of the circuit, cannulae, and the physiology of gas exchange with ECMO are necessary to ensure lung rest, efficiency of oxygenation, and ventilation as well as troubleshooting problems. Anticoagulation is a major concern with ECMO, and the evidence is evolving with respect to diagnostic testing and use of anticoagulants. Clinical management of the patient includes comprehensive critical care addressing sedation and neurologic issues, ensuring lung recruitment, diuresis, early enteral nutrition, treatment and surveillance of infections, and multisystem organ support. Newer technology that delinks oxygenation and ventilation by extracorporeal carbon dioxide removal may lead to ultra-lung protective ventilation, avoidance of endotracheal intubation in some situations, and ambulatory therapies as a bridge to lung transplantation. Risks, complications, and long-term outcomes and resources need to be considered and weighed in before widespread application. Ethical challenges are a reality and a multidisciplinary approach that should be adopted for every case in consideration.

Obesity: challenges to ventilatory control during exercise--a brief review.

PubMed

Babb, Tony G

2013-11-01

Obesity is a national health issue in the US. Among the many physiological changes induced by obesity, it also presents a unique challenge to ventilatory control during exercise due to increased metabolic demand of moving larger limbs, increased work of breathing due to extra weight on the chest wall, and changes in breathing mechanics. These challenges to ventilatory control in obesity can be inconspicuous or overt among obese adults but for the most part adaptation of ventilatory control during exercise in obesity appears remarkably unnoticed in the majority of obese people. In this brief review, the changes to ventilatory control required for maintaining normal ventilation during exercise will be examined, especially the interaction between respiratory neural drive and ventilation. Also, gaps in our current knowledge will be discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

Strategies for maximizing your chances for weaning success. Limitations--and advantages--of common predictive indices.

PubMed

Patel, R G; Petrini, M F; Norman, J R

1995-06-01

Using indices to predict weaning outcome can avoid premature extubation and unnecessary prolongation of ventilatory support. Unfortunately, none of the indices is consistently able to predict outcome. The key to successful weaning is to assess respiratory function repeatedly with several indices, not just one. The patient should be able to sustain spontaneous breathing for at least 24 hours on minimal partial ventilatory support (a pressure support or a continuous positive airway pressure of 5 cm H2O or a T piece, for example). Indices of maximal inspiratory pressure; work of breathing; and rapid, shallow breathing are useful in evaluating a patient's respiratory muscle performance; airway occlusion pressure is helpful as well when increased neuromuscular drive is a problem.

Blockade of phosphodiesterase 4 reverses morphine-induced ventilatory disturbance without loss of analgesia.

PubMed

Kimura, Satoko; Ohi, Yoshiaki; Haji, Akira

2015-04-15

Ventilatory disturbance is a fatal side-effect of opioid analgesics. Separation of analgesia from ventilatory depression is important for therapeutic use of opioids. It has been suggested that opioid-induced ventilatory depression results from a decrease in adenosine 3',5'-cyclic monophosphate content in the respiratory-related neurons. Therefore, we examined the effects of caffeine, a methylxanthine non-selective phosphodiesterase (PDE) inhibitor with adenosine antagonistic activity, and rolipram, a racetam selective PDE4 inhibitor, on ventilatory depression induced by morphine. Spontaneous ventilation and paw withdrawal responses to nociceptive thermal stimulation were measured in anesthetized rats simultaneously. The efferent discharge of the phrenic nerve was recorded in anesthetized, vagotomized, paralyzed and artificially ventilated rats. Rolipram (0.1 and 0.3 mg/kg, i.v.) and caffeine (3.0 and 10.0 mg/kg, i.v.) relieved morphine (1.0 mg/kg, i.v.)-induced ventilatory depression but had no discernible effect on its analgesic action. Rolipram (0.3 and 1.0 mg/kg, i.v.) and caffeine (10.0 and 20.0 mg/kg, i.v.) recovered morphine (3.0 mg/kg, i.v.)-induced prolongation and flattening of inspiratory discharge in the phrenic nerve. Inhibition of PDE4 may be a possible approach for overcoming morphine-induced ventilatory depression without loss of analgesia. Copyright © 2015 Elsevier Inc. All rights reserved.

Ventilatory drive and the apnea-hypopnea index in six-to-twelve year old children

PubMed Central

Fregosi, Ralph F; Quan, Stuart F; Jackson, Andrew C; Kaemingk, Kris L; Morgan, Wayne J; Goodwin, Jamie L; Reeder, Jenny C; Cabrera, Rosaria K; Antonio, Elena

2004-01-01

Background We tested the hypothesis that ventilatory drive in hypoxia and hypercapnia is inversely correlated with the number of hypopneas and obstructive apneas per hour of sleep (obstructive apnea hypopnea index, OAHI) in children. Methods Fifty children, 6 to 12 years of age were studied. Participants had an in-home unattended polysomnogram to compute the OAHI. We subsequently estimated ventilatory drive in normoxia, at two levels of isocapnic hypoxia, and at three levels of hyperoxic hypercapnia in each subject. Experiments were done during wakefulness, and the mouth occlusion pressure measured 0.1 seconds after inspiratory onset (P0.1) was measured in all conditions. The slope of the relation between P0.1 and the partial pressure of end-tidal O2 or CO2 (PETO2 and PETCO2) served as the index of hypoxic or hypercapnic ventilatory drive. Results Hypoxic ventilatory drive correlated inversely with OAHI (r = -0.31, P = 0.041), but the hypercapnic ventilatory drive did not (r = -0.19, P = 0.27). We also found that the resting PETCO2 was significantly and positively correlated with the OAHI, suggesting that high OAHI values were associated with resting CO2 retention. Conclusions In awake children the OAHI correlates inversely with the hypoxic ventilatory drive and positively with the resting PETCO2. Whether or not diminished hypoxic drive or resting CO2 retention while awake can explain the severity of sleep-disordered breathing in this population is uncertain, but a reduced hypoxic ventilatory drive and resting CO2 retention are associated with sleep-disordered breathing in 6–12 year old children. PMID:15117413

Increased ventilatory response to carbon dioxide in COPD patients following vitamin C administration

PubMed Central

Hartmann, Sara E.; Kissel, Christine K.; Szabo, Lian; Walker, Brandie L.; Leigh, Richard; Anderson, Todd J.

2015-01-01

Patients with chronic obstructive pulmonary disease (COPD) have decreased ventilatory and cerebrovascular responses to hypercapnia. Antioxidants increase the ventilatory response to hypercapnia in healthy humans. Cerebral blood flow is an important determinant of carbon dioxide/hydrogen ion concentration at the central chemoreceptors and may be affected by antioxidants. It is unknown whether antioxidants can improve the ventilatory and cerebral blood flow response in individuals in whom these are diminished. Thus, we aimed to determine the effect of vitamin C administration on the ventilatory and cerebrovascular responses to hypercapnia during healthy ageing and in COPD. Using transcranial Doppler ultrasound, we measured the ventilatory and cerebral blood flow responses to hyperoxic hypercapnia before and after an intravenous vitamin C infusion in healthy young (Younger) and older (Older) subjects and in moderate COPD. Vitamin C increased the ventilatory response in COPD patients (mean (95% CI) 1.1 (0.9–1.1) versus 1.5 (1.1–2.0) L·min−1·mmHg−1, p<0.05) but not in Younger (2.5 (1.9–3.1) versus 2.4 (1.9–2.9) L·min−1·mmHg−1, p>0.05) or Older (1.3 (1.0–1.7) versus 1.3 (1.0–1.7) L·min−1·mmHg−1, p>0.05) healthy subjects. Vitamin C did not affect the cerebral blood flow response in the young or older healthy subjects or COPD subjects (p>0.05). Vitamin C increases the ventilatory but not cerebrovascular response to hyperoxic hypercapnia in patients with moderate COPD. PMID:27730137

Medullary serotonergic neurones modulate the ventilatory response to hypercapnia, but not hypoxia in conscious rats.

PubMed

Taylor, Natalie C; Li, Aihua; Nattie, Eugene E

2005-07-15

Serotonergic neurones in the mammalian medullary raphe region (MRR) have been implicated in central chemoreception and the modulation of the ventilatory response to hypercapnia, and may also be involved in the ventilatory response to hypoxia. In this study, we ask whether ventilatory responses across arousal states are affected when the 5-hydroxytryptamine 1A receptor (5-HT1A) agonist (R)-(+)-8-hydroxy-2(di-n-propylamino)tetralin (DPAT) is microdialysed into the MRR of the unanaesthetized adult rat. Microdialysis of 1, 10 and 30 mM DPAT into the MRR significantly decreased absolute ventilation values(VE) during 7% CO2 breathing by 21%, 19% and 30%, respectively, in wakefulness compared to artificial cerebrospinal fluid (aCSF) microdialysis, due to decreases in tidal volume (VT) and not in frequency (f), similar to what occurred during non-rapid eye movement (NREM) sleep. The concentration-dependence of the hypercapnic ventilatory effect might be due to differences in tissue distribution of DPAT. DPAT (30 mM) changed room air breathing pattern by increasing f and decreasing VT. As evidenced by a sham control group, repeated experimentation and microdialysis of aCSF alone had no effect on the ventilatory response to 7% CO2 during wakefulness or sleep. Unlike during hypercapnia, microdialysis of 30 mM DPAT into the MRR did not change the ventilatory response to 10% O2. Additionally, 10 and 30 mM DPAT MRR microdialysis decreased body temperature, and 30 mM DPAT increased the percentage of experimental time in wakefulness. We conclude that serotonergic activity in the MRR plays a role in the ventilatory response to hypercapnia, but not to hypoxia, and that MRR 5-HT1A receptors are also involved in thermoregulation and arousal.

Recombinant human deoxyribonuclease improves atelectasis in mechanically ventilated children with cardiac disease.

PubMed

Prodhan, Parthak; Greenberg, B; Bhutta, Adnan T; Hyde, Carrie; Vankatesan, Ajay; Imamura, Michiaki; Jaquiss, Robert Db; Dyamenahalli, Umesh

2009-01-01

To investigate whether a mucolytic agent, recombinant human deoxyribonuclease (rhDNase), improves atelectasis in children with cardiac illness requiring mechanical ventilation. A retrospective cohort study on consecutive patients receiving short-term (< or =14 days) rhDNase therapy for atelectasis in the cardiac intensive care unit from January 2005 through February 2007 was carried out. Data relating to patient characteristics, gas exchange, ventilatory parameters, and chest radiographs were collected and analyzed. The effectiveness of rhDNase therapy in the presence of neutrophils and/or bacteria in the pre-rhDNase therapy tracheal aspirates was also investigated. rhDNase was effective in significantly improving established atelectasis without any major changes in gas exchange and ventilatory parameters. Therapeutic effect of rhDNase is most effective in ameliorating atelectasis in the lungs within 10 doses. rhDNase was more effective in improving chest radiographic atelectasis score in patients who had > moderate amounts of polymophonuclear neutrophils (P value = 0.0008), or bacteria (P value = 0.007) or both (P value = 0.004) present in their pre-rhDNase therapy trachea aspirate. No adverse effects were seen with rhDNase administration in the study cohort. rhDNase can be safely and effectively used to improve atelectasis in mechanically ventilated children with cardiac disease especially in the presence of bacteria and/or moderate amounts of polymophonuclear neutrophils in the pre-rhDNase therapy tracheal aspirate.

Recombinant Human Deoxyribonuclease Improves Atelectasis in Mechanically Ventilated Children with Cardiac Disease

PubMed Central

Prodhan, P; Greenberg, B; Bhutta, AT; Hyde, C; Vankatesan, A; Imamura, M; Jaquiss, RDB; Dyamenahalli, U

2010-01-01

Objective To investigate if a mucolytic agent, recombinant human deoxyribonuclease (rhDNase), improves atelectasis in children with cardiac illness requiring mechanical ventilation. Design A retrospective cohort study on consecutive patients receiving short-term (≤ 14 days) rhDNase therapy for atelectasis in the cardiac intensive care unit from January 2005 through February 2007 was carried out. Data relating to patient characteristics, gas exchange, ventilatory parameters and chest radiographs was collected and analyzed. The effectiveness of rhDNase therapy in the presence of neutrophils and/ or bacteria in the pre-rhDNase therapy tracheal aspirates was also investigated. Results rhDNase was effective in significantly improving established atelectasis without any major changes in gas exchange and ventilatory parameters. Therapeutic effect of rhDNase is most effective in ameliorating atelectasis in the lungs within 10 doses. rhDNase was more effective in improving chest radiographic atelectasis score in patients who had > moderate amounts PMN (p value= 0.0008), or bacteria (p value=0.007) or both (p value =0.004) present in their pre-rhDNase therapy trachea aspirate. No adverse effects were seen with rhDNase administration in the study cohort. Conclusions rhDNase can be safely and effectively used to improve atelectasis in mechanically ventilated children with cardiac disease especially in the presence of bacteria and/ or moderate amounts of PMN in the pre-rhDNase therapy tracheal aspirate. PMID:19489944

ARDS: challenges in patient care and frontiers in research.

PubMed

Bos, Lieuwe D; Martin-Loeches, Ignacio; Schultz, Marcus J

2018-03-31

This review discusses the clinical challenges associated with ventilatory support and pharmacological interventions in patients with acute respiratory distress syndrome (ARDS). In addition, it discusses current scientific challenges facing researchers when planning and performing trials of ventilatory support or pharmacological interventions in these patients.Noninvasive mechanical ventilation is used in some patients with ARDS. When intubated and mechanically ventilated, ARDS patients should be ventilated with low tidal volumes. A plateau pressure <30 cmH 2 O is recommended in all patients. It is suggested that a plateau pressure <15 cmH 2 O should be considered safe. Patient with moderate and severe ARDS should receive higher levels of positive end-expiratory pressure (PEEP). Rescue therapies include prone position and neuromuscular blocking agents. Extracorporeal support for decapneisation and oxygenation should only be considered when lung-protective ventilation is no longer possible, or in cases of refractory hypoxaemia, respectively. Tracheotomy is only recommended when prolonged mechanical ventilation is expected.Of all tested pharmacological interventions for ARDS, only treatment with steroids is considered to have benefit.Proper identification of phenotypes, known to respond differently to specific interventions, is increasingly considered important for clinical trials of interventions for ARDS. Such phenotypes could be defined based on clinical parameters, such as the arterial oxygen tension/inspiratory oxygen fraction ratio, but biological marker profiles could be more promising. Copyright ©ERS 2018.

Respiratory-function changes in textile workers exposed to synthetic fibers.

PubMed

Valic, F; Zuskin, E

1977-01-01

The prevalence of respiratory symptoms and acute and chronic changes in ventilatory function were studied in three groups of textile workers: 68 workers with exposure to synthetic fibers only, 30 with previous exposure to cotton, and 77 with previous exposure to hemp. The prevalence of dyspnea, grade 3 to 4, was significantly lower (P less than .01) in workers with a history of exposure to synthetic fibers only than in those previously exposed to hemp or cotton. No case of byssinosis was found in any of the workers studied. Values in ventilatory-function tests (FEV 1.0, FVC and MEF 50%) were significantly reduced during the work shift on Monday and Thursday. The Monday MEF 50% preshift values were significantly lower than expected in all three groups of workers. A comparison of the 1963-1973 data on the 77 workers previously exposed to hemp showed a lower prevalence of most chronic respiratory symptoms and smaller acute FEV1.0 and FVC reductions when they worked with synthetic fibers (1973) than when they were exposed to hemp (1963).

Linking Inflammation, Cardiorespiratory Variability, and Neural Control in Acute Inflammation via Computational Modeling

PubMed Central

Dick, Thomas E.; Molkov, Yaroslav I.; Nieman, Gary; Hsieh, Yee-Hsee; Jacono, Frank J.; Doyle, John; Scheff, Jeremy D.; Calvano, Steve E.; Androulakis, Ioannis P.; An, Gary; Vodovotz, Yoram

2012-01-01

Acute inflammation leads to organ failure by engaging catastrophic feedback loops in which stressed tissue evokes an inflammatory response and, in turn, inflammation damages tissue. Manifestations of this maladaptive inflammatory response include cardio-respiratory dysfunction that may be reflected in reduced heart rate and ventilatory pattern variabilities. We have developed signal-processing algorithms that quantify non-linear deterministic characteristics of variability in biologic signals. Now, coalescing under the aegis of the NIH Computational Biology Program and the Society for Complexity in Acute Illness, two research teams performed iterative experiments and computational modeling on inflammation and cardio-pulmonary dysfunction in sepsis as well as on neural control of respiration and ventilatory pattern variability. These teams, with additional collaborators, have recently formed a multi-institutional, interdisciplinary consortium, whose goal is to delineate the fundamental interrelationship between the inflammatory response and physiologic variability. Multi-scale mathematical modeling and complementary physiological experiments will provide insight into autonomic neural mechanisms that may modulate the inflammatory response to sepsis and simultaneously reduce heart rate and ventilatory pattern variabilities associated with sepsis. This approach integrates computational models of neural control of breathing and cardio-respiratory coupling with models that combine inflammation, cardiovascular function, and heart rate variability. The resulting integrated model will provide mechanistic explanations for the phenomena of respiratory sinus-arrhythmia and cardio-ventilatory coupling observed under normal conditions, and the loss of these properties during sepsis. This approach holds the potential of modeling cross-scale physiological interactions to improve both basic knowledge and clinical management of acute inflammatory diseases such as sepsis and trauma. PMID:22783197

Rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation (ROHHAD): Response to ventilatory challenges.

PubMed

Carroll, Michael S; Patwari, Pallavi P; Kenny, Anna S; Brogadir, Cindy D; Stewart, Tracey M; Weese-Mayer, Debra E

2015-12-01

Hypoventilation is a defining feature of Rapid-onset Obesity with Hypothalamic dysfunction, Hypoventilation and Autonomic Dysregulation (ROHHAD), a rare respiratory and autonomic disorder. This chronic hypoventilation has been explained as the result of dysfunctional chemosensory control circuits, possibly affecting peripheral afferent input, central integration, or efferent motor control. However, chemosensory function has never been quantified in a cohort of ROHHAD patients. Therefore, the purpose of this study was to assess the response to awake ventilatory challenge testing in children and adolescents with ROHHAD. The ventilatory, cardiovascular and cerebrovascular responses in 25 distinct comprehensive physiological recordings from seven unique ROHHAD patients to three different gas mixtures were analyzed at breath-to-breath and beat-to-beat resolution as absolute measures, as change from baseline, or with derived metrics. Physiologic measures were recorded during a 3-min baseline period of room air, a 3-min gas exposure (of 100% O2; 95% O2, 5% CO2; or 14% O2, 7% CO2 balanced with N2), and a 3-min recovery period. An additional hypoxic challenge was conducted which consisted of either five or seven tidal breaths of 100% N2. While ROHHAD cases showed a diminished VT and inspiratory drive response to hypoxic hypercapnia and absent behavioral awareness of the physiologic compromise, most ventilatory, cardiovascular, and cerebrovascular measures were similar to those of previously published controls using an identical protocol, suggesting a mild chemosensory deficit. Nonetheless, the high mortality rate, comorbidity and physiological fragility of patients with ROHHAD demand continued clinical vigilance. © 2015 Wiley Periodicals, Inc.

Linking Inflammation, Cardiorespiratory Variability, and Neural Control in Acute Inflammation via Computational Modeling.

PubMed

Dick, Thomas E; Molkov, Yaroslav I; Nieman, Gary; Hsieh, Yee-Hsee; Jacono, Frank J; Doyle, John; Scheff, Jeremy D; Calvano, Steve E; Androulakis, Ioannis P; An, Gary; Vodovotz, Yoram

2012-01-01

Acute inflammation leads to organ failure by engaging catastrophic feedback loops in which stressed tissue evokes an inflammatory response and, in turn, inflammation damages tissue. Manifestations of this maladaptive inflammatory response include cardio-respiratory dysfunction that may be reflected in reduced heart rate and ventilatory pattern variabilities. We have developed signal-processing algorithms that quantify non-linear deterministic characteristics of variability in biologic signals. Now, coalescing under the aegis of the NIH Computational Biology Program and the Society for Complexity in Acute Illness, two research teams performed iterative experiments and computational modeling on inflammation and cardio-pulmonary dysfunction in sepsis as well as on neural control of respiration and ventilatory pattern variability. These teams, with additional collaborators, have recently formed a multi-institutional, interdisciplinary consortium, whose goal is to delineate the fundamental interrelationship between the inflammatory response and physiologic variability. Multi-scale mathematical modeling and complementary physiological experiments will provide insight into autonomic neural mechanisms that may modulate the inflammatory response to sepsis and simultaneously reduce heart rate and ventilatory pattern variabilities associated with sepsis. This approach integrates computational models of neural control of breathing and cardio-respiratory coupling with models that combine inflammation, cardiovascular function, and heart rate variability. The resulting integrated model will provide mechanistic explanations for the phenomena of respiratory sinus-arrhythmia and cardio-ventilatory coupling observed under normal conditions, and the loss of these properties during sepsis. This approach holds the potential of modeling cross-scale physiological interactions to improve both basic knowledge and clinical management of acute inflammatory diseases such as sepsis and trauma.

Carotid body potentiation during chronic intermittent hypoxia: implication for hypertension

PubMed Central

Del Rio, Rodrigo; Moya, Esteban A.; Iturriaga, Rodrigo

2014-01-01

Autonomic dysfunction is involved in the development of hypertension in humans with obstructive sleep apnea, and animals exposed to chronic intermittent hypoxia (CIH). It has been proposed that a crucial step in the development of the hypertension is the potentiation of the carotid body (CB) chemosensory responses to hypoxia, but the temporal progression of the CB chemosensory, autonomic and hypertensive changes induced by CIH are not known. We tested the hypothesis that CB potentiation precedes the autonomic imbalance and the hypertension in rats exposed to CIH. Thus, we studied the changes in CB chemosensory and ventilatory responsiveness to hypoxia, the spontaneous baroreflex sensitivity (BRS), heart rate variability (HRV) and arterial blood pressure in pentobarbital anesthetized rats exposed to CIH for 7, 14, and 21 days. After 7 days of CIH, CB chemosensory and ventilatory responses to hypoxia were enhanced, while BRS was significantly reduced by 2-fold in CIH-rats compared to sham-rats. These alterations persisted until 21 days of CIH. After 14 days, CIH shifted the HRV power spectra suggesting a predominance of sympathetic over parasympathetic tone. In contrast, hypertension was found after 21 days of CIH. Concomitant changes between the gain of spectral HRV, BRS, and ventilatory hypoxic chemoreflex showed that the CIH-induced BRS attenuation preceded the HRV changes. CIH induced a simultaneous decrease of the BRS gain along with an increase of the hypoxic ventilatory gain. Present results show that CIH-induced persistent hypertension was preceded by early changes in CB chemosensory control of cardiorespiratory and autonomic function. PMID:25429271

Ventilatory effects of gap junction blockade in the RTN in awake rats.

PubMed

Hewitt, Amy; Barrie, Rachel; Graham, Michael; Bogus, Kara; Leiter, J C; Erlichman, Joseph S

2004-12-01

We tested the hypothesis that carbenoxolone, a pharmacological inhibitor of gap junctions, would reduce the ventilatory response to CO(2) when focally perfused within the retrotrapezoid nucleus (RTN). We tested this hypothesis by measuring minute ventilation (V(E)), tidal volume (V(T)), and respiratory frequency (F(R)) responses to increasing concentrations of inspired CO(2) (Fi(CO(2)) = 0-8%) in rats during wakefulness. We confirmed that the RTN was chemosensitive by perfusing the RTN unilaterally with either acetazolamide (AZ; 10 microM) or hypercapnic artificial cerebrospinal fluid equilibrated with 50% CO(2) (pH approximately 6.5). Focal perfusion of AZ or hypercapnic aCSF increased V(E), V(T), and F(R) during exposure to room air. Carbenoxolone (300 microM) focally perfused into the RTN decreased V(E) and V(T) in animals <11 wk of age, but V(E) and V(T) were increased in animals >12 wk of age. Glyzyrrhizic acid, a congener of carbenoxolone, did not change V(E), V(T), or F(R) when focally perfused into the RTN. Carbenoxolone binds to the mineralocorticoid receptor, but spironolactone (10 microM) did not block the disinhibition of V(E) or V(T) in older animals when combined with carbenoxolone. Thus the RTN is a CO(2) chemosensory site in all ages tested, but the function of gap junctions in the chemosensory process varies substantially among animals of different ages: gap junctions amplify the ventilatory response to CO(2) in younger animals, but appear to inhibit the ventilatory response to CO(2) in older animals.

[Continuous lateral rotation or kinetic therapy: an update of knowledge].

PubMed

Calaf Tost, Carles; Comas Miquel, Emma

2005-01-01

Acute lung injury and, when extreme, acute respiratory distress syndrome, are thought to be expression of a diffuse and overwhelming inflammatory reaction of the pulmonary capillary membrane to a variety of causes. The ventilatory support is essential in this patients. In the last years we know the significance of the postural treatment in this type of patients through the prone positioning. The continuous lateral rotation therapy or kinetic therapy (KT) is the new manner by other positioning beside the technological advances. Lowly it's introducing in our setting. The follow article would respound the next questions: What's the KT? How must to make the KT? What recommendations have been offered by specialists from the complications? Which is it efectivity?

Studies of Ventilatory Capacity and Histamine Response during Exposure to Isocyanate Vapour in Polyurethane Foam Manufacture

PubMed Central

Gandevia, Bryan

1963-01-01

Complaints of respiratory symptoms amongst workers in a factory using isocyanate to produce polyurethane foam led to a study of changes in ventilatory capacity in the course of several working days. Mean decreases of the order of 0·181. were observed in the forced expiratory volume at one second in 15 employees during each of three normal working shifts. No significant change occurred on days when a process involving the liberation of isocyanate was stopped, or when the men were given an oral aminophylline compound prophylactically. An aerosol of isoprenaline failed to reverse the decrease in ventilatory capacity observed during one normal working day. Approximately half the subjects studied were found to show increased bronchial sensitivity to a histamine aerosol; all were smokers, whereas none of the non-smokers showed a significant (over 10%) reduction in ventilatory capacity after histamine. Smokers and/or positive histamine reactors tended to show a greater decrease in ventilatory capacity during a working day than non-smokers or non-reactors. The present findings, which confirm clinical reports of adverse respiratory effects of isocyanate in low concentrations, are compared with other studies of ventilatory capacity during occupational exposure to respiratory irritants. PMID:14046157

[Peak oxygen uptake during the six-minute walk test in diffuse interstitial lung disease and pulmonary hypertension].

PubMed

Blanco, Isabel; Villaquirán, Claudio; Valera, José Luis; Molina-Molina, María; Xaubet, Antoni; Rodríguez-Roisin, Robert; Barberà, Joan A; Roca, Josep

2010-03-01

The six-minute walk test (6MWT) is widely used in evaluating diffuse interstitial lung disease (ILD) and pulmonary hypertension (PH). However, their physiological determining factors have not been well defined. To evaluate the physiological changes that occur in ILD and PH during the 6MWT, and compare them with the cardiopulmonary exercise test (CPET). Thirteen patients with ILD and 14 with PH were studied using the 6MWT and CPET on an ergometer cycle. The respiratory variables were recorded by means of telemetry during the 6MWT. Oxygen consumption (VO(2)), respiratory and heart rate reached a plateau from minute 3 of the 6MWT in both diseases. The VO(2) did not differ from the peak value in the CPET (14+/-2 and 15+/-2 ml/kg/min, respectively, in ILD; 16+/-6 and 16+/-6 ml/kg/min, in PH). The arterial oxygen saturation decreased in both diseases, although it was more marked in ILD (-12+/-5%, p<0,01). The ventilatory equivalent for CO(2) (V(E)/VCO(2)) in PH during the 6MWT was strongly associated with functional class (FC) (85+/-14 in FC III-IV, 44+/-6 in FC I-II; p<0,001). The 6MWT in ILD and PH behaves like a maximal effort test, with similar VO(2) to the CPET, demonstrating a limit in oxygen transport capacity. Monitoring using telemetry during the 6MWT may be useful for the clinical evaluation of patients with ILD or PH. Copyright 2009 SEPAR. Published by Elsevier Espana. All rights reserved.

Maintenance of equine anaesthesia over the last 50 years: Controlled inhalation of volatile anaesthetics and pulmonary ventilation.

PubMed

Mosing, M; Senior, J M

2018-05-01

In the first edition of this journal, Barbara Weaver wrote a review titled 'Equine Anaesthesia', stating that, at that time, it was quickly becoming accepted practice that many horses were being anaesthetised 'by essentially similar procedures, i.e. premedication, induction and then maintenance by controlled inhalation'. To celebrate the 50th anniversary of the first edition of this journal, this review covers the development of understanding and practice of inhalational anaesthesia and controlled ventilation in horses over the last 50 years. We review how the perceived benefits of halothane led to its widespread use, but subsequently better understanding of halothane's effects led to changes in equine anaesthetic practice and the utilisation of different inhalation agents (e.g. isoflurane and sevoflurane). We discuss how more recently, better understanding of the effects of the 'newer' inhalation agents' effects has led to yet more changes in equine anaesthetic practice, and while, further new inhalation agents are unlikely to appear in the near future, further enhancements to anaesthetic practice may still lead to improved outcomes. We review advances in our understanding of the anatomy and pathophysiology of the equine lung as well of the effects of anaesthesia on lung function and how these predispose to some of the common problems of gas exchange and ventilation during anaesthesia. We identify the aims of optimal mechanical ventilation for anaesthetic management and whether the various methods of ventilatory support during equine anaesthesia achieve them. We also highlight that further developments in equipment and optimal ventilator modes are likely in the near future. © 2017 EVJ Ltd.

Acute exacerbation of idiopathic pulmonary fibrosis: lessons learned from acute respiratory distress syndrome?

PubMed

Marchioni, Alessandro; Tonelli, Roberto; Ball, Lorenzo; Fantini, Riccardo; Castaniere, Ivana; Cerri, Stefania; Luppi, Fabrizio; Malerba, Mario; Pelosi, Paolo; Clini, Enrico

2018-03-23

Idiopathic pulmonary fibrosis (IPF) is a fibrotic lung disease characterized by progressive loss of lung function and poor prognosis. The so-called acute exacerbation of IPF (AE-IPF) may lead to severe hypoxemia requiring mechanical ventilation in the intensive care unit (ICU). AE-IPF shares several pathophysiological features with acute respiratory distress syndrome (ARDS), a very severe condition commonly treated in this setting.A review of the literature has been conducted to underline similarities and differences in the management of patients with AE-IPF and ARDS.During AE-IPF, diffuse alveolar damage and massive loss of aeration occurs, similar to what is observed in patients with ARDS. Differently from ARDS, no studies have yet concluded on the optimal ventilatory strategy and management in AE-IPF patients admitted to the ICU. Notwithstanding, a protective ventilation strategy with low tidal volume and low driving pressure could be recommended similarly to ARDS. The beneficial effect of high levels of positive end-expiratory pressure and prone positioning has still to be elucidated in AE-IPF patients, as well as the precise role of other types of respiratory assistance (e.g., extracorporeal membrane oxygenation) or innovative therapies (e.g., polymyxin-B direct hemoperfusion). The use of systemic drugs such as steroids or immunosuppressive agents in AE-IPF is controversial and potentially associated with an increased risk of serious adverse reactions.Common pathophysiological abnormalities and similar clinical needs suggest translating to AE-IPF the lessons learned from the management of ARDS patients. Studies focused on specific therapeutic strategies during AE-IPF are warranted.

Exercise training with negative pressure ventilation improves exercise capacity in patients with severe restrictive lung disease: a prospective controlled study

PubMed Central

2013-01-01

Background Exercise training is of benefit for patients with restrictive lung disease. However, it tends to be intolerable for those with severe disease. We examined whether providing ventilatory assistance by using negative pressure ventilators (NPV) during exercise training is feasible for such patients and the effects of training. Methods 36 patients with restrictive lung disease were prospectively enrolled for a 12-week multidisciplinary rehabilitation program. During this program, half of them (n:18; 60.3 ± 11.6 years; 6 men; FVC: 32.5 ± 11.7% predicted ) received regular sessions of exercise training under NPV, whilst the 18 others (59.6 ± 12.3 years; 8 men; FVC: 37.7 ± 10.2% predicted) did not. Exercise capacity, pulmonary function, dyspnea and quality of life were measured. The primary endpoint was the between-group difference in change of 6 minute-walk distance (6MWD) after 12 weeks of rehabilitation. Results All patients in the NPV-exercise group were able to tolerate and completed the program. The between-group differences were significantly better in the NPV-exercise group in changes of 6MWD (34.1 ± 12.7 m vs. -32.5 ± 17.5 m; P = 0.011) and St George Score (−14.5 ± 3.6 vs. 11.8 ± 6.0; P < 0.01). There was an improvement in dyspnea sensation (Borg’s scale, from 1.4 ± 1.5 point to 0.8 ± 1.3 point, P = 0.049) and a small increase in FVC (from 0.85 ± 0.09 L to 0.91 ± 0.08 L, P = 0.029) in the NPV-exercise group compared to the control group. Conclusion Exercise training with NPV support is feasible for patients with severe restrictive lung diseases, and improves exercise capacity and health-related quality of life. PMID:23421438

New modes of assisted mechanical ventilation.

PubMed

Suarez-Sipmann, F

2014-05-01

Recent major advances in mechanical ventilation have resulted in new exciting modes of assisted ventilation. Compared to traditional ventilation modes such as assisted-controlled ventilation or pressure support ventilation, these new modes offer a number of physiological advantages derived from the improved patient control over the ventilator. By implementing advanced closed-loop control systems and using information on lung mechanics, respiratory muscle function and respiratory drive, these modes are specifically designed to improve patient-ventilator synchrony and reduce the work of breathing. Depending on their specific operational characteristics, these modes can assist spontaneous breathing efforts synchronically in time and magnitude, adapt to changing patient demands, implement automated weaning protocols, and introduce a more physiological variability in the breathing pattern. Clinicians have now the possibility to individualize and optimize ventilatory assistance during the complex transition from fully controlled to spontaneous assisted ventilation. The growing evidence of the physiological and clinical benefits of these new modes is favoring their progressive introduction into clinical practice. Future clinical trials should improve our understanding of these modes and help determine whether the claimed benefits result in better outcomes. Copyright © 2013 Elsevier España, S.L. and SEMICYUC. All rights reserved.

Chorioamnionitis and chronic lung disease of prematurity: a path analysis of causality.

PubMed

Dessardo, Nada Sindičić; Mustać, Elvira; Dessardo, Sandro; Banac, Srđan; Peter, Branimir; Finderle, Aleksandar; Marić, Marinko; Haller, Herman

2012-02-01

Current evidence suggests that additional pathogenetic factors could play a role in the development of chronic lung disease of prematurity, other than mechanical ventilation and free radical injury. The introduction of the concept of "fetal inflammatory response syndrome" offers a new perspective on the pathogenesis of chronic lung disease of prematurity. New statistical approaches could be useful tools in evaluating causal relationships in the development of chronic morbidity in preterm infants. The aim of this study was to test a new statistical framework incorporating path analysis to evaluate causality between exposure to chorioamnionitis and fetal inflammatory response syndrome and the development of chronic lung disease of prematurity. We designed a prospective cohort study that included consecutively born premature infants less than 32 weeks of gestation whose placentas were collected for histological analysis. Histological chorioamnionitis, clinical data, and neonatal outcomes were related to chronic lung disease. Along with standard statistical methods, a path analysis was performed to test the relationship between histological chorioamnionitis, gestational age, mechanical ventilation, and development of chronic lung disease of prematurity. Among the newborns enrolled in the study, 69/189 (36%) had histological chorioamnionitis. Of those with histological chorioamnionitis, 28/69 (37%) were classified as having fetal inflammatory response syndrome, according to the presence of severe chorioamnionitis and funisitis. Histological chorioamnionitis was associated with a lower birth weight, shorter gestation, higher frequency of patent ductus arteriosus, greater use of surfactant, and higher frequency of chronic lung disease of prematurity. Severe chorioamnionitis and funisitis were significantly associated with lower birth weight, lower gestational age, lower Apgar score at 5 minutes, more frequent use of mechanical ventilatory support and surfactant, as well as higher frequency of patent ductus arteriosus and chronic lung disease. The results of the path analysis showed that fetal inflammatory response syndrome has a significant direct (0.66), indirect (0.11), and overall (0.77) effect on chronic lung disease. This study demonstrated a strong positive correlation between exposure of the fetus to a severe inflammatory response and the development of chronic lung disease of prematurity. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

A model of mechanical interactions between heart and lungs.

PubMed

Fontecave Jallon, Julie; Abdulhay, Enas; Calabrese, Pascale; Baconnier, Pierre; Gumery, Pierre-Yves

2009-12-13

To study the mechanical interactions between heart, lungs and thorax, we propose a mathematical model combining a ventilatory neuromuscular model and a model of the cardiovascular system, as described by Smith et al. (Smith, Chase, Nokes, Shaw & Wake 2004 Med. Eng. Phys.26, 131-139. (doi:10.1016/j.medengphy.2003.10.001)). The respiratory model has been adapted from Thibault et al. (Thibault, Heyer, Benchetrit & Baconnier 2002 Acta Biotheor. 50, 269-279. (doi:10.1023/A:1022616701863)); using a Liénard oscillator, it allows the activity of the respiratory centres, the respiratory muscles and rib cage internal mechanics to be simulated. The minimal haemodynamic system model of Smith includes the heart, as well as the pulmonary and systemic circulation systems. These two modules interact mechanically by means of the pleural pressure, calculated in the mechanical respiratory system, and the intrathoracic blood volume, calculated in the cardiovascular model. The simulation by the proposed model provides results, first, close to experimental data, second, in agreement with the literature results and, finally, highlighting the presence of mechanical cardiorespiratory interactions.

Disintegration of the 'waterfall phenomenon' in the inferior vena cava due to right heart failure.

PubMed

Kira, S; Dambara, T; Mieno, T; Tamaki, S; Natori, H

1996-03-01

The concept of the waterfall phenomenon in Zone 2 in the pulmonary vasculature is well known from West's lung model. It is believed that the flow through this zone is determined by the pressure difference between the pulmonary artery and alveoli, and the left atrial pressure is not transmissible to the alveolar capillaries. However, it is impossible to see whether alveolar capillaries are really displaying the waterfall phenomenon or not. In this review, the interrelation between the flow and geometry of the alveolar capillaries in the waterfall phenomenon is analyzed based on physiological studies using a model system and isolated lung lobe experiments. Further, extending the concept to the analysis of ventilatory changes of the inferior vena cava (IVC) configuration, it is ascertained that the waterfall phenomenon normally occurs in the IVC during inspiration just before it enters the thorax and the waterfall phenomenon in the IVC disintegrates with elevation of the central venous pressure. Because these configurations of the IVC in normal and abnormal conditions are visible with ultrasonography, the technique is very useful as a noninvasive approach to diagnose right heart failure.

Chest ultrasounds to guide manual reexpansion of a postoperative pulmonary atelectasis: a case report.

PubMed

Cavaliere, F; Biasucci, D; Costa, R; Soave, M; Addabbo, G; Proietti, R

2011-07-01

Reexpansion of a pulmonary atelectasis is often difficult, even after removing possible causes of bronchial obstruction. Chest ultrasounds, inexpensive and readily available at the patient bedside, may offer valuable support to guide recruitment maneuvers. We report the case of a 57-year-old woman that developed a complete collapse of the left lung seven days after undergoing an intestinal resection for perforation. A mucous plug occluding the main bronchus was removed with bronchoscopy, but persistent hypoxemia required mechanical ventilation; 24 hours later, an attempt to wean the patient from the ventilator failed. Chest X-rays revealed the persistence of a partial collapse of the left inferior lobe associated with a pleural effusion. A chest ultrasound confirmed the presence of a lung consolidation and of a modest pleural effusion. Manual reexpansion was then attempted, and ventilatory pressures as well as the duration of forced inspirations were based on real-time ultrasound images. Complete reexpansion was achieved within a few minutes and confirmed by chest X-ray. The patient was weaned from mechanical ventilation on the same day and discharged from ICU three days later.

Pleural mechanics and fluid exchange.

PubMed

Lai-Fook, Stephen J

2004-04-01

The pleural space separating the lung and chest wall of mammals contains a small amount of liquid that lubricates the pleural surfaces during breathing. Recent studies have pointed to a conceptual understanding of the pleural space that is different from the one advocated some 30 years ago in this journal. The fundamental concept is that pleural surface pressure, the result of the opposing recoils of the lung and chest wall, is the major determinant of the pressure in the pleural liquid. Pleural liquid is not in hydrostatic equilibrium because the vertical gradient in pleural liquid pressure, determined by the vertical gradient in pleural surface pressure, does not equal the hydrostatic gradient. As a result, a viscous flow of pleural liquid occurs in the pleural space. Ventilatory and cardiogenic motions serve to redistribute pleural liquid and minimize contact between the pleural surfaces. Pleural liquid is a microvascular filtrate from parietal pleural capillaries in the chest wall. Homeostasis in pleural liquid volume is achieved by an adjustment of the pleural liquid thickness to the filtration rate that is matched by an outflow via lymphatic stomata.

Acrolein inhalation alters myocardial synchrony and performance at and below exposure concentrations that cause ventilatory responses

EPA Science Inventory

Acrolein is an irritating aldehyde generated during combustion of organic compounds. Altered autonomic activity has been documented following acrolein inhalation, possibly impacting myocardial synchrony and function. Given the ubiquitous nature of acrolein in the environment, we ...

Mechanical ventilation and sepsis impair protein metabolism in the diaphragm of neonatal pigs

USDA-ARS?s Scientific Manuscript database

Mechanical ventilation (MV) impairs diaphragmatic function and diminishes the ability to wean from ventilatory support in adult humans. In normal neonatal pigs, animals that are highly anabolic, endotoxin (LPS) infusion induces sepsis, reduces peripheral skeletal muscle protein synthesis rates, but ...

Effect of substance P on cardiovascular and respiratory function in subjects.

PubMed

Fuller, R W; Maxwell, D L; Dixon, C M; McGregor, G P; Barnes, V F; Bloom, S R; Barnes, P J

1987-04-01

The effect of substance P (SP), administered both intravenously and by inhalation, has been studied in normal and asthmatic humans. Intravenous infusion of SP (0.2-3.3 pmol X kg-1 X min-1) achieving a plasma concentration of SP between 5 and 25 pM produced vasodilatation (mean +/- SD), maximal increase in skin temperature (0.9 +/- 0.3 degree C) (P less than 0.05), and fall in diastolic blood pressure (8.5 +/- 2.9 mmHg) (P less than 0.05) associated with an increase in heart rate (15 +/- 10 beats/min) (P less than 0.05). All subjects had a fall in Vp30 (airflow at 70% of forced vital capacity measured from total lung capacity after a forced partial expiratory flow maneuver) at low infusion rate (P less than 0.05) and a significant rise at the highest infusion rate (P less than 0.05). Ventilation at rest and when stimulated by transient hypoxia increased (mean increase in resting ventilation 0.73 +/- 0.4 l/min and mean percent increase in transient ventilatory hypoxic response 41 +/- 27%). There was a small nonsignificant increase in plasma norepinephrine but no change in epinephrine or histamine. Inhaled SP, up to 0.7 mumol, caused a small nonsignificant fall in airway function in asthmatic subjects. SP has demonstrable effects on vascular smooth muscle and control of ventilation but at the doses studied had little effect on airway function.

High fat diet blunts the effects of leptin on ventilation and on carotid body activity.

PubMed

Ribeiro, Maria J; Sacramento, Joana F; Gallego-Martin, Teresa; Olea, Elena; Melo, Bernardete F; Guarino, Maria P; Yubero, Sara; Obeso, Ana; Conde, Silvia V

2017-12-22

Leptin plays a role in the control of breathing, acting mainly on central nervous system; however, leptin receptors have been recently shown to be expressed in the carotid body (CB), and this finding suggests a physiological role for leptin in the regulation of CB function. Leptin increases minute ventilation in both basal and hypoxic conditions in rats. It increases the frequency of carotid sinus nerve discharge in basal conditions, as well as the release of adenosine from the CB. However, in a metabolic syndrome animal model, the effects of leptin in ventilatory control, carotid sinus nerve activity and adenosine release by the CB are blunted. Although leptin may be involved in triggering CB overactivation in initial stages of obesity and dysmetabolism, resistance to leptin signalling and blunting of responses develops in metabolic syndrome animal models. Leptin plays a role in the control of breathing, acting mainly on central nervous system structures. Leptin receptors are expressed in the carotid body (CB) and this finding has been associated with a putative physiological role of leptin in the regulation of CB function. Since, the CBs are implicated in energy metabolism, here we tested the effects of different concentrations of leptin administration on ventilatory parameters and on carotid sinus nerve (CSN) activity in control and high-fat (HF) diet fed rats, in order to clarify the role of leptin in ventilation control in metabolic disease states. We also investigated the expression of leptin receptors and the neurotransmitters involved in leptin signalling in the CBs. We found that in non-disease conditions, leptin increases minute ventilation in both basal and hypoxic conditions. However, in the HF model, the effect of leptin in ventilatory control is blunted. We also observed that HF rats display an increased frequency of CSN discharge in basal conditions that is not altered by leptin, in contrast to what is observed in control animals. Leptin did not modify intracellular Ca 2+ in CB chemoreceptor cells, but it produced an increase in the release of adenosine from the whole CB. We conclude that CBs represent an important target for leptin signalling, not only to coordinate peripheral ventilatory chemoreflexive drive, but probably also to modulate metabolic variables. We also concluded that leptin signalling is mediated by adenosine release and that HF diets blunt leptin responses in the CB, compromising ventilatory adaptation. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

Sustained microgravity reduces the human ventilatory response to hypoxia but not to hypercapnia.

PubMed

Prisk, G K; Elliott, A R; West, J B

2000-04-01

We measured the isocapnic hypoxic ventilatory response and the hypercapnic ventilatory response by using rebreathing techniques in five normal subjects (ages 37-47 yr) before, during, and after 16 days of exposure to microgravity (microG). Control measurements were performed with the subjects in the standing and supine postures. In both microG and in the supine position, the hypoxic ventilatory response, as measured from the slope of ventilation against arterial O(2) saturation, was greatly reduced, being only 46 +/- 10% (microG) and 52 +/- 11% (supine) of that measured standing (P < 0.01). During the hypercapnic ventilatory response test, the ventilation at a PCO(2) of 60 Torr was not significantly different in microG (101 +/- 5%) and the supine position (89 +/- 3%) from that measured standing. Inspiratory occlusion pressures agreed with these results. The findings can be explained by inhibition of the hypoxic but not hypercapnic drive, possibly as a result of an increase in blood pressure in carotid baroreceptors in microG and the supine position.

Metabolic and ventilatory responses to submaximal and maximal exercise using different breathing assemblies.

PubMed

Evans, B W; Potteiger, J A

1995-06-01

This study compared ventilatory and metabolic responses during exercise using three breathing assemblies: mouthpiece/noseclip (BV); mouth/face mask (MM); and facemask (FM). Ten male runners completed three maximal treadmill tests with breathing assembly randomly assigned. Metabolic and ventilatory data were recorded every 15s, and heart rate (HR) and rating of perceived exertion (RPE) each min. No significant differences were found for treadmill run time, HRmax, respiratory exchange ratio (RER), and RPE, indicating similar efforts on all trials. No significant differences were found at maximal exercise for VO2 minute ventilation (VE), tidal volume (VT), and breathing frequency (f). At ventilatory threshold (TVENT), VO2, VE, and f were not significantly different. However, peak flow (PF) was significantly higher for BV than FM, and VT was significantly higher for BV than MM and FM. Results indicate alterations in ventilatory mechanics occur at TVENT, but type of breathing assembly does not significantly affect maximal values.

Ventilatory effects of substance P, vasoactive intestinal peptide, and nitroprusside in humans.

PubMed

Maxwell, D L; Fuller, R W; Dixon, C M; Cuss, F M; Barnes, P J

1990-01-01

Animal studies suggest that the neuropeptides, substance P and vasoactive intestinal peptide (VIP), may influence carotid body chemoreceptor activity and that substance P may take part in the carotid body response to hypoxia. The effects of these peptides on resting ventilation and on ventilatory responses to hypoxia and to hypercapnia have been investigated in six normal humans. Infusions of substance P (1 pmol.kg-1.min-1) and of VIP (6 pmol.kg-1.min-1) were compared with placebo and with nitroprusside (5 micrograms.kg-1.min-1) as a control for the hypotensive action of the peptides. Both peptides caused significantly less hypotension than nitroprusside. Substance P and nitroprusside caused significantly greater increases in ventilation and in the hypoxic ventilatory response than VIP. No changes were seen in hypercapnic sensitivity. The stimulation of ventilation and the differential effects on ventilatory chemosensitivity that accompanied hypotension are consistent either with stimulation of carotid body chemoreceptor activity or with an interaction with peripheral chemoreceptor input to the respiratory center, as is seen in animals. The similar cardiovascular but different ventilatory effects of the peptides suggest that substance P may also stimulate the carotid body in a manner independent of the effect of hypotension. This is consistent with a role of substance P in the hypoxic ventilatory response in humans.

Cardiopulmonary function after pulmonary contusion and partial liquid ventilation.

PubMed

Moomey, C B; Fabian, T C; Croce, M A; Melton, S M; Proctor, K G

1998-08-01

To compare the effects of mechanical ventilation with either positive end-expiratory pressure (PEEP) or partial liquid ventilation (PLV) on cardiopulmonary function after severe pulmonary contusion. Mongrel pigs (32 +/- 1 kg) were anesthetized, paralyzed, and mechanically ventilated (8-10 mL/kg tidal volume; 12 breaths/min; FiO2 = 0.5). Systemic hemodynamics and pulmonary function were measured for 7 hours after a captive bolt gun delivered a blunt injury to the right chest. After 5 hours, FiO2 was increased to 1.0 and either PEEP (n = 7) in titrated increments to 25 cm H2O or PLV with perflubron (LiquiVent, 30 mL/kg, endotracheal) and no PEEP (n = 7) was administered for 2 hours. Two control groups received injury without treatment (n = 6) or no injury with PLV (n = 3). Fluids were liberalized with PEEP versus PLV (27 +/- 3 vs. 18 +/- 2 mL.kg-1.h-1) to maintain cardiac filling pressures. Before treatment at 5 hours after injury, physiologic dead space fraction (30 +/- 4%), pulmonary vascular resistance (224 +/- 20% of baseline), and airway resistance (437 +/- 110% of baseline) were all increased (p < 0.05). In addition, PaO2/FiO2 had decreased to 112 +/- 18 mm Hg, compliance was depressed to 11 +/- 1 mL/cm H2O (36 +/- 3% of baseline), and shunt fraction was increased to 22 +/- 4% (all p < 0.05). Blood pressure and cardiac index remained stable relative to baseline, but stroke index and systemic oxygen delivery were depressed by 15 to 30% (both p < 0.05). After 2 hours of treatment with PEEP versus PLV, PO2/FiO2 was higher (427 +/- 20 vs. 263 +/- 37) and dead space ventilation was lower (4 +/- 3 vs. 28 +/- 7%) (both p < 0.05), whereas compliance tended to be higher (26 +/- 2 vs. 20 +/- 2) and shunt fraction tended to be lower (0 +/- 0 vs. 7 +/- 4). With PEEP versus PLV, however, cardiac index, stroke index, and systemic oxygen delivery were 30 to 60% lower (all p < 0.05). Furthermore, although contused lungs showed similar damage with either treatment, the secondary injury in the contralateral lung (as manifested by intra-alveolar hemorrhage) was more severe with PEEP than with PLV. Both PEEP and PLV improved pulmonary function after severe unilateral pulmonary contusion, but negative hemodynamic and histologic changes were associated with PEEP and not with PLV. These data suggest that PLV is a promising novel ventilatory strategy for unilateral pulmonary contusion that might ameliorate secondary injury in the contralateral uninjured lung.

Phenotyping Pharyngeal Pathophysiology using Polysomnography in Patients with Obstructive Sleep Apnea.

PubMed

Sands, Scott A; Edwards, Bradley A; Terrill, Philip I; Taranto-Montemurro, Luigi; Azarbarzin, Ali; Marques, Melania; Hess, Lauren B; White, David P; Wellman, Andrew

2018-05-01

Therapies for obstructive sleep apnea (OSA) could be administered on the basis of a patient's own phenotypic causes ("traits") if a clinically applicable approach were available. Here we aimed to provide a means to quantify two key contributors to OSA-pharyngeal collapsibility and compensatory muscle responsiveness-that is applicable to diagnostic polysomnography. Based on physiological definitions, pharyngeal collapsibility determines the ventilation at normal (eupneic) ventilatory drive during sleep, and pharyngeal compensation determines the rise in ventilation accompanying a rising ventilatory drive. Thus, measuring ventilation and ventilatory drive (e.g., during spontaneous cyclic events) should reveal a patient's phenotypic traits without specialized intervention. We demonstrate this concept in patients with OSA (N = 29), using a novel automated noninvasive method to estimate ventilatory drive (polysomnographic method) and using "gold standard" ventilatory drive (intraesophageal diaphragm EMG) for comparison. Specialized physiological measurements using continuous positive airway pressure manipulation were employed for further comparison. The validity of nasal pressure as a ventilation surrogate was also tested (N = 11). Polysomnography-derived collapsibility and compensation estimates correlated favorably with those quantified using gold standard ventilatory drive (R = 0.83, P < 0.0001; and R = 0.76, P < 0.0001; respectively) and using continuous positive airway pressure manipulation (R = 0.67, P < 0.0001; and R = 0.64, P < 0.001; respectively). Polysomnographic estimates effectively stratified patients into high versus low subgroups (accuracy, 69-86% vs. ventilatory drive measures; P < 0.05). Traits were near-identical using nasal pressure versus pneumotach (N = 11, R ≥ 0.98, both traits; P < 0.001). Phenotypes of pharyngeal dysfunction in OSA are evident from spontaneous changes in ventilation and ventilatory drive during sleep, enabling noninvasive phenotyping in the clinic. Our approach may facilitate precision therapeutic interventions for OSA.

Dose monitoring in Partial Liquid Ventilation by infrared measurement of expired perfluorochemicals.

PubMed

Mazzoni, M; Nugent, L; Klein, D; Hoffman, J; Sekins, K M; Flaim, S F

1999-01-01

Patients undergoing Partial Liquid Ventilation (PLV) with the perfluorochemical liquid perflubron (PFB) continuously evaporate the drug from the lung during ventilatory expiration. In this study, two infrared (IR) devices, a modified industrial analyzer ("experimental prototype") and a custom-designed device suitable for use in a clinical environment ("clinical prototype"), were calibrated and validated on the bench to measure a range of PFB concentrations (CPFB) in a gas stream. PFB loss from the lung (area under the CPFB-vs-time-curve) could be correlated during PLV simulation with changes in tidal volume, breathing rate, and variable CPFB-vs-time profiles. The two IR devices produced nearly identical measurements for the same CPFB standards (maximum deviation = 1.5%). The experimental IR prototype was tested in 17 anesthetized, paralyzed, and ventilated swine (42-53 kg) to quantify the total amount and rate of evaporate loss of PFB over 12 hours of PLV, both with and without periodic supplemental PFB doses. The residual PFB volumes in the animal lungs at the end of the study, as determined by a gravimetric postmortem lung method, were found to agree on average for all animals to within 10% of the residual PFB volume as predicted by the IR approach. Furthermore, the IR signal of CPFB does not appear to correlate with the absolute amount of PFB in the lungs, but may reflect the relative proportion of PFB-wetted airway and alveolar surface. The authors conclude that IR quantitation of PFB evaporative loss is acceptably accurate for extended periods of PLV and may be a useful tool in the clinic for PFB dose monitoring and maintenance, thereby helping to optimize PLV treatment.

The clinical course of anesthetic induction in lung transplant recipients with pulmonary complications after hematopoietic stem cell transplantation.

PubMed

Mizota, Toshiyuki; Matsukawa, Shino; Fukagawa, Hiroshi; Daijo, Hiroki; Tanaka, Tomoharu; Chen, Fengshi; Date, Hiroshi; Fukuda, Kazuhiko

2015-08-01

We examined the clinical course of anesthetic induction in lung transplant recipients with pulmonary complications after hematopoietic stem cell transplantation (post-HSCT), focusing on ventilatory management. We aimed to determine the incidence of oxygen desaturation during anesthetic induction and severe respiratory acidosis after anesthetic induction in post-HSCT lung transplant recipients, and to explore factors associated with their development. Nineteen consecutive patients who underwent lung transplantation post-HSCT at Kyoto University Hospital (Japan) were retrospectively studied. Data regarding patient characteristics, preoperative examination, and clinical course during anesthetic induction were analyzed. The incidence of oxygen desaturation (SpO2 < 90 %) during anesthetic induction and severe respiratory acidosis (pH < 7.2) after anesthetic induction were 21.1 and 26.3 %, respectively. Reduced dynamic compliance (Cdyn) during mechanical ventilation was significantly associated with oxygen desaturation during anesthetic induction (p = 0.01), as well as severe respiratory acidosis after anesthetic induction (p = 0.01). The preoperative partial pressure of carbon dioxide in arterial blood (PaCO2; r = -0.743, p = 0.002) and body mass index (BMI; r = 0.61, p = 0.021) significantly correlated with Cdyn, and multivariate analysis revealed that both PaCO2 and BMI were independently associated with Cdyn. Oxygen desaturation during anesthetic induction and severe respiratory acidosis after anesthetic induction frequently occur in post-HSCT lung transplant recipients. Low Cdyn may, at least partially, explain oxygen desaturation during anesthetic induction and severe respiratory acidosis after anesthetic induction. Moreover, preoperative hypercapnia and low BMI were predictive of low Cdyn.

Mechanical ventilation alone, and in the presence of sepsis, impair protein metabolism in the diaphragm of neonatal pigs

USDA-ARS?s Scientific Manuscript database

Mechanical ventilation (MV) impairs diaphragmatic function and diminishes the ability to wean from ventilatory support in adult humans. In normal neonatal pigs, animals that are highly anabolic, endotoxin (LPS) infusion induces sepsis, reduces peripheral skeletal muscle protein synthesis rates, but ...

Respiratory muscles stretching acutely increases expansion in hemiparetic chest wall.

PubMed

Rattes, Catarina; Campos, Shirley Lima; Morais, Caio; Gonçalves, Thiago; Sayão, Larissa Bouwman; Galindo-Filho, Valdecir Castor; Parreira, Verônica; Aliverti, Andrea; Dornelas de Andrade, Armèle

2018-08-01

Individuals post-stroke may present restrictive ventilatory pattern generated from changes in the functionality of respiratory system due to muscle spasticity and contractures. Objective was to assess the acute effects after respiratory muscle stretching on the ventilatory pattern and volume distribution of the chest wall in stroke subjects. Ten volunteers with right hemiparesis after stroke and a mean age of 60 ± 5.7 years were randomised into the following interventions: respiratory muscle stretching and at rest (control). The ventilatory pattern and chest wall volume distribution were evaluated through optoelectronic plethysmography before and immediately after each intervention. Respiratory muscle stretching promoted a significant acute increase of 120 mL in tidal volume, with an increase in minute ventilation, mean inspiratory flow and mean expiratory flow compared with the control group. Pulmonary ribcage increased 50 mL after stretching, with 30 mL of contribution to the right pulmonary rib cage (hemiparetic side) in comparison to the control group. Respiratory muscle stretching in patients with right hemiparesis post-stroke demonstrated that acute effects improve the expansion of the respiratory system during tidal breathing. NCT02416349 (URL: https://clinicaltrials.gov/ct2/show/ NCT02416349). Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of movement and work load in patients with congenital central hypoventilation syndrome.

PubMed

Hager, Alfred; Koch, Walter; Stenzel, Heike; Hess, John; Schöber, Johannes

2007-04-01

Patients with congenital central hypoventilation syndrome lack ventilatory chemosensitivity and depend at least in part on the ergoreceptor function during exercise. In these patients a substantial increase of ventilation has been reported for passive movement during sleep as well as active movement on a treadmill. The aim of the study was to investigate ventilatory response to an increasing work load with constant movement. Eighteen patients and 17 healthy volunteers performed a cardiopulmonary exercise test on a bicycle pedaling at a constant rate of about 60 revolutions per minute throughout the entire test. The patients were able to exercise adequately and showed normal peak oxygen uptake. There was a steep rise in minute ventilation in both groups at the start of exercise, yet there was only a minor increase in both groups during the increase of workload up to the anaerobic threshold. After the anaerobic threshold, there was again an increase in ventilation in both groups, but the increase was less prominent in the patient group. Ventilation in patients with congenital central hypoventilation syndrome is increased during exercise caused both by movement (mechanoreceptors) and by anaerobic workload. This facilitates a normal ventilatory drive up to the anaerobic threshold and a normal exercise capacity in these patients.

A caseian point for the evolution of a diaphragm homologue among the earliest synapsids.

PubMed

Lambertz, Markus; Shelton, Christen D; Spindler, Frederik; Perry, Steven F

2016-12-01

The origin of the diaphragm remains a poorly understood yet crucial step in the evolution of terrestrial vertebrates, as this unique structure serves as the main respiratory motor for mammals. Here, we analyze the paleobiology and the respiratory apparatus of one of the oldest lineages of mammal-like reptiles: the Caseidae. Combining quantitative bone histology and functional morphological and physiological modeling approaches, we deduce a scenario in which an auxiliary ventilatory structure was present in these early synapsids. Crucial to this hypothesis are indications that at least the phylogenetically advanced caseids might not have been primarily terrestrial but rather were bound to a predominantly aquatic life. Such a lifestyle would have resulted in severe constraints on their ventilatory system, which consequently would have had to cope with diving-related problems. Our modeling of breathing parameters revealed that these caseids were capable of only limited costal breathing and, if aquatic, must have employed some auxiliary ventilatory mechanism to quickly meet their oxygen demand upon surfacing. Given caseids' phylogenetic position at the base of Synapsida and under this aquatic scenario, it would be most parsimonious to assume that a homologue of the mammalian diaphragm had already evolved about 50 Ma earlier than previously assumed. © 2016 New York Academy of Sciences.

The ventilatory responsiveness to CO2 below eupnoea as a determinant of ventilatory stability in sleep

PubMed Central

Dempsey, Jerome A; Smith, Curtis A; Przybylowski, Tadeuez; Chenuel, Bruno; Xie, Ailiang; Nakayama, Hideaki; Skatrud, James B

2004-01-01

Sleep unmasks a highly sensitive hypocapnia-induced apnoeic threshold, whereby apnoea is initiated by small transient reductions in arterial CO2 pressure (PaCO2) below eupnoea and respiratory rhythm is not restored until PaCO2 has risen significantly above eupnoeic levels. We propose that the ‘CO2 reserve’ (i.e. the difference in PaCO2 between eupnoea and the apnoeic threshold (AT)), when combined with ‘plant gain’ (or the ventilatory increase required for a given reduction in PaCO2) and ‘controller gain’ (ventilatory responsiveness to CO2 above eupnoea) are the key determinants of breathing instability in sleep. The CO2 reserve varies inversely with both plant gain and the slope of the ventilatory response to reduced CO2 below eupnoea; it is highly labile in non-random eye movement (NREM) sleep. With many types of increases or decreases in background ventilatory drive and PaCO2, the slope of the ventilatory response to reduced PaCO2 below eupnoea remains unchanged from control. Thus, the CO2 reserve varies inversely with plant gain, i.e. it is widened with hyperventilation and narrowed with hypoventilation, regardless of the stimulus and whether it acts primarily at the peripheral or central chemoreceptors. However, there are notable exceptions, such as hypoxia, heart failure, or increased pulmonary vascular pressures, which all increase the slope of the CO2 response below eupnoea and narrow the CO2 reserve despite an accompanying hyperventilation and reduced plant gain. Finally, we review growing evidence that chemoreceptor-induced instability in respiratory motor output during sleep contributes significantly to the major clinical problem of cyclical obstructive sleep apnoea. PMID:15284345

Why do nonsurvivors from community-acquired pneumonia not receive ventilatory support?

PubMed

Bauer, Torsten T; Welte, Tobias; Strauss, Richard; Bischoff, Helge; Richter, Klaus; Ewig, Santiago

2013-08-01

We investigated rates and predictors of ventilatory support during hospitalization in seemingly not severely compromised nonsurvivors of community-acquired pneumonia (CAP). We used the database from the German nationwide mandatory quality assurance program including all hospitalized patients with CAP from 2007 to 2011. We selected a population not residing in nursing homes, not bedridden, and not referred from another hospital. Predictors of ventilatory support were identified using a multivariate analysis. Overall, 563,901 patients (62.3% of the whole population) were included. Mean age was 69.4 ± 16.6 years; 329,107 (58.4%) were male. Mortality was 39,895 (7.1%). A total of 28,410 (5.0%) received ventilatory support during the hospital course, and 76.3% of nonsurvivors did not receive ventilatory support (62.6% of those aged <65 years and 78% of those aged ≥65 years). Higher age (relative risk (RR) 0.48, 95% confidence interval (CI) 0.44-0.51), failure to assess gas exchange (RR 0.18, 95% CI 0.14-0.25) and to administer antibiotics within 8 h of hospitalization (RR 0.48, 95% CI 0.39-0.59) were predictors of not receiving ventilatory support during hospitalization. Death from CAP occurred significantly earlier in the nonventilated group (8.2 ± 8.9 vs. 13.1 ± 14.1 days; p < 0.0001). The number of nonsurvivors without obvious reasons for withholding ventilatory support is disturbingly high, particularly in younger patients. Both performance predictors for not being ventilated remain ambiguous, because they may reflect either treatment restrictions or deficient clinical performance. Elucidating this ambiguity will be part of the forthcoming update of the quality assurance program.

Brain stem NO modulates ventilatory acclimatization to hypoxia in mice.

PubMed

El Hasnaoui-Saadani, R; Alayza, R Cardenas; Launay, T; Pichon, A; Quidu, P; Beaudry, M; Léon-Velarde, F; Richalet, J P; Duvallet, A; Favret, F

2007-11-01

The objective of our study was to assess the role of neuronal nitric oxide synthase (nNOS) in the ventilatory acclimatization to hypoxia. We measured the ventilation in acclimatized Bl6/CBA mice breathing 21% and 8% oxygen, used a nNOS inhibitor, and assessed the expression of N-methyl-d-aspartate (NMDA) glutamate receptor and nNOS (mRNA and protein). Two groups of Bl6/CBA mice (n = 60) were exposed during 2 wk either to hypoxia [barometric pressure (PB) = 420 mmHg] or normoxia (PB = 760 mmHg). At the end of exposure the medulla was removed to measure the concentration of nitric oxide (NO) metabolites, the expression of NMDA-NR1 receptor, and nNOS by real-time RT-PCR and Western blot. We also measured the ventilatory response [fraction of inspired O(2) (Fi(O(2))) = 0.21 and 0.08] before and after S-methyl-l-thiocitrulline treatment (SMTC, nNOS inhibitor, 10 mg/kg ip). Chronic hypoxia caused an increase in ventilation that was reduced after SMTC treatment mainly through a decrease in tidal volume (Vt) in normoxia and in acute hypoxia. However, the difference observed in the magnitude of acute hypoxic ventilatory response [minute ventilation (Ve) 8% - Ve 21%] in acclimatized mice was not different. Acclimatization to hypoxia induced a rise in NMDA receptor as well as in nNOS and NO production. In conclusion, our study provides evidence that activation of nNOS is involved in the ventilatory acclimatization to hypoxia in mice but not in the hypoxic ventilatory response (HVR) while the increased expression of NMDA receptor expression in the medulla of chronically hypoxic mice plays a role in acute HVR. These results are therefore consistent with central nervous system plasticity, partially involved in ventilatory acclimatization to hypoxia through nNOS.

Low Cardiorespiratory Fitness is Partially Linked to Ventilatory Factors in Obese Adolescents.

PubMed

Mendelson, Monique; Michallet, Anne-Sophie; Tonini, Julia; Favre-Juvin, Anne; Guinot, Michel; Wuyam, Bernard; Flore, Patrice

2016-02-01

To examine the role of ventilatory constraint on cardiorespiratory fitness in obese adolescents. Thirty obese adolescents performed a maximal incremental cycling exercise and were divided into 2 groups based on maximal oxygen uptake (VO2peak): those presenting low (L; n = 15; VO2peak: 72.9 ± 8.6% predicted) or normal (N; n = 15; VO2peak: 113.6 ± 19.2% predicted) cardiorespiratory fitness. Both were compared with a group of healthy controls (C; n = 20; VO2peak: 103.1 ± 11.2% predicted). Ventilatory responses were explored using the flow volume loop method. Cardiorespiratory fitness (VO2peak, in % predicted) was lower in L compared with C and N and was moderately associated with the percent predicted forced vital capacity (FVC) (r = .52; p < .05) in L. At peak exercise, end inspiratory point was lower in L compared with N and C (77.4 ± 8.1, 86.4 ± 7.7, and 89.9 ± 7.6% FVC in L, N, and C, respectively; p < .05), suggesting an increased risk of ventilatory constraint in L, although at peak exercise this difference could be attributed to the lower maximal ventilation in L. Forced vital capacity and ventilatory strategy to incremental exercise slightly differed between N and L. These results suggest a modest participation of ventilatory factors to exercise intolerance.

[Periodic oscillating respiration outside of comatous stages].

PubMed

Jammes, Y; Delpierre, S; Zwirn, P; Nicoli, M M

1977-04-01

A periodic oscillating breathing was observed in 11 subjects during study of their pulmonary function. All these patients were male and more than 50 years old. A cardiovascular disease was clinically evident in eight of them. Arterial hypoxemia was found in five subjects and a light hypocapnia in three. Analysis of oscillating rhythms first, revealed unexistence of ventilatory pauses between periods of deep breaths in some subjects and secondly, showed existence of permanent or discontinuous periodic rhythms. Breath by breath changes in ventilation were essentially induced by oscillations in tidal volume. Discontinuous oscillating breathing appeared after forced maximal inspiration and this periodic rhythm was frequently associated with sights. This periodic breathing began or persisted under progressive hypoxia but disappeared under normobaric hyperoxia. These data are discussed in terms of changes in the ventilatory control system and in central regulation of breathing patterns.

Chronic respiratory disfunction due to diffuse alveolar hemorrhage in patients with systemic lupus erythematosus and primary vasculitis.

PubMed

Pérez Aceves, Eva; Pérez Cristóbal, Mario; Espinola Reyna, Gerardo A; Ariza Andraca, Raul; Xibille Fridmann, Daniel; Barile Fabris, Leonor A

2013-01-01

Pulmonary hemorrhage (PH) occurs in 2-5% of SLE patients, and is associated with a high mortality rate (79-90%). Diagnostic criteria for this complication include: 1) Pulmonary infiltrates, with at least ¾ of lung tissue involved in a chest x ray, 2) Acute respiratory failure, 3) A decrease of 3g/dL or more in hemoglobin levels. PH might lead to organized pneumonia, collagen deposition, and pulmonary fibrosis which in time might cause changes in pulmonary function tests with either restrictive or obstructive patterns. To evaluate the existence of abnormalities in pulmonary function tests after a PH episode. We included patients with SLE and primary vasculitis that developed PH. During the acute episode, we measured SLEDAI in SLE patients, five factor score in microscopic polyangiitis (MPA) and Birmingham Vasculitis Activity Store (BVAS) in granulomatosis with polyangiitis (GPA) (Wegener). We determined the number of PH events, treatment, and ventilator assistance requirements and correlated its association with abnormal pulmonary function tests. We included 10 patients, 7 with SLE, 2 with MPA and 1 with GPA (Wegener). The mean activity measures were: SLEDAI 20.4 ± 7.5, FFS 2, and BVAS 36. Treatment consisted in methylprednisolone (MPD) in 3 patients, MPD plus cyclophosphamide (CY) in 6 patients, and MPD, CY, IV immunoglobulin, and plasmapheresis in one patient. Five patients required ventilatory support. We found abnormalities in pulmonary function tests in 8 patients, three had an obstructive pattern and five a restrictive pattern; 2 patients did not show any change. We did not find a significant association with any of the studied variables. PH might cause abnormalities in pulmonary function tests and prolonged immunosuppressive treatment could be required. Copyright © 2012 Elsevier España, S.L. All rights reserved.

Impact of forced vital capacity loss on survival after the onset of chronic lung allograft dysfunction.

PubMed

Todd, Jamie L; Jain, Rahil; Pavlisko, Elizabeth N; Finlen Copeland, C Ashley; Reynolds, John M; Snyder, Laurie D; Palmer, Scott M

2014-01-15

Emerging evidence suggests a restrictive phenotype of chronic lung allograft dysfunction (CLAD) exists; however, the optimal approach to its diagnosis and clinical significance is uncertain. To evaluate the hypothesis that spirometric indices more suggestive of a restrictive ventilatory defect, such as loss of FVC, identify patients with distinct clinical, radiographic, and pathologic features, including worse survival. Retrospective, single-center analysis of 566 consecutive first bilateral lung recipients transplanted over a 12-year period. A total of 216 patients developed CLAD during follow-up. CLAD was categorized at its onset into discrete physiologic groups based on spirometric criteria. Imaging and histologic studies were reviewed when available. Survival after CLAD diagnosis was assessed using Kaplan-Meier and Cox proportional hazards models. Among patients with CLAD, 30% demonstrated an FVC decrement at its onset. These patients were more likely to be female, have radiographic alveolar or interstitial changes, and histologic findings of interstitial fibrosis. Patients with FVC decline at CLAD onset had significantly worse survival after CLAD when compared with those with preserved FVC (P < 0.0001; 3-yr survival estimates 9% vs. 48%, respectively). The deleterious impact of CLAD accompanied by FVC loss on post-CLAD survival persisted in a multivariable model including baseline demographic and clinical factors (P < 0.0001; adjusted hazard ratio, 2.73; 95% confidence interval, 1.86-4.04). At CLAD onset, a subset of patients demonstrating physiology more suggestive of restriction experience worse clinical outcomes. Further study of the biologic mechanisms underlying CLAD phenotypes is critical to improving long-term survival after lung transplantation.

Influence of locomotor muscle afferent inhibition on the ventilatory response to exercise in heart failure.

PubMed

Olson, Thomas P; Joyner, Michael J; Eisenach, John H; Curry, Timothy B; Johnson, Bruce D

2014-02-01

What is the central question of this study? Patients with heart failure often develop ventilatory abnormalities at rest and during exercise, but the mechanisms underlying these abnormalities remain unclear. This study investigated the influence of inhibiting afferent neural feedback from locomotor muscles on the ventilatory response during exercise in heart failure patients. What is the main finding and its importance? Our results suggest that inhibiting afferent feedback from locomotor muscle via intrathecal opioid administration significantly reduces the ventilatory response to exercise in heart failure patients. Patients with heart failure (HF) develop ventilatory abnormalities at rest and during exercise, but the mechanism(s) underlying these abnormalities remain unclear. We examined whether the inhibition of afferent neural feedback from locomotor muscles during exercise reduces exercise ventilation in HF patients. In a randomized, placebo-controlled design, nine HF patients (age, 60 ± 2 years; ejection fraction, 27 ± 2%; New York Heart Association class 2 ± 1) and nine control subjects (age, 63 ± 2 years) underwent constant-work submaximal cycling (65% peak power) with intrathecal fentanyl (impairing the cephalad projection of opioid receptor-sensitive afferents) or sham injection. The hypercapnic ventilatory response was measured to determine whether cephalad migration of fentanyl occurred. There were no differences in hypercapnic ventilatory response within or between groups in either condition. Despite a lack of change in ventilation, tidal volume or respiratory rate, HF patients had a mild increase in arterial carbon dioxide (P(aCO(2)) and a decrease in oxygen (P(aO(2)); P < 0.05 for both) at rest. The control subjects demonstrated no change in P(aCO(2)), P(aO(2)), ventilation, tidal volume or respiratory rate at rest. In response to fentanyl during exercise, HF patients had a reduction in ventilation (63 ± 6 versus 44 ± 3 l min(-1), P < 0.05) due to a lower respiratory rate (30 ± 1 versus 26 ± 2 breaths min(-1), P < 0.05). The reduced ventilation resulted in lower P aO 2 (97.6 ± 2.5 versus 79.5 ± 3.0 mmHg, P < 0.05) and increased P(aCO(2)) (37.3 ± 0.9 versus 43.5 ± 1.1 mmHg, P < 0.05), with significant improvement in ventilatory efficiency (reduction in the ventilatory equivalent for carbon dioxide; P < 0.05 for all). The control subjects had no change in ventilation or measures of arterial blood gases. These data suggest that inhibition of afferent feedback from locomotor muscle significantly reduces the ventilatory response to exercise in HF patients.

CESAR: conventional ventilatory support vs extracorporeal membrane oxygenation for severe adult respiratory failure.

PubMed

Peek, Giles J; Clemens, Felicity; Elbourne, Diana; Firmin, Richard; Hardy, Pollyanna; Hibbert, Clare; Killer, Hilliary; Mugford, Miranda; Thalanany, Mariamma; Tiruvoipati, Ravin; Truesdale, Ann; Wilson, Andrew

2006-12-23

An estimated 350 adults develop severe, but potentially reversible respiratory failure in the UK annually. Current management uses intermittent positive pressure ventilation, but barotrauma, volutrauma and oxygen toxicity can prevent lung recovery. An alternative treatment, extracorporeal membrane oxygenation, uses cardio-pulmonary bypass technology to temporarily provide gas exchange, allowing ventilator settings to be reduced. While extracorporeal membrane oxygenation is proven to result in improved outcome when compared to conventional ventilation in neonates with severe respiratory failure, there is currently no good evidence from randomised controlled trials to compare these managements for important clinical outcomes in adults, although evidence from case series is promising. The aim of the randomised controlled trial of Conventional ventilatory support vs extracorporeal membrane oxygenation for severe adult respiratory failure (CESAR) is to assess whether, for patients with severe, but potentially reversible, respiratory failure, extracorporeal membrane oxygenation will increase the rate of survival without severe disability ('confined to bed' and 'unable to wash or dress') by six months post-randomisation, and be cost effective from the viewpoints of the NHS and society, compared to conventional ventilatory support. Following assent from a relative, adults (18-65 years) with severe, but potentially reversible, respiratory failure (Murray score >/= 3.0 or hypercapnea with pH < 7.2) will be randomised for consideration of extracorporeal membrane oxygenation at Glenfield Hospital, Leicester or continuing conventional care in a centre providing a high standard of conventional treatment. The central randomisation service will minimise by type of conventional treatment centre, age, duration of high pressure ventilation, hypoxia/hypercapnea, diagnosis and number of organs failed, to ensure balance in key prognostic variables. Extracorporeal membrane oxygenation will not be available for patients meeting entry criteria outside the trial. 180 patients will be recruited to have 80% power to be able to detect a one third reduction in the primary outcome from 65% at 5% level of statistical significance (2-sided test). Secondary outcomes include patient morbidity and health status at 6 months. Analysis will be based on intention to treat. A concurrent economic evaluation will also be performed to compare the costs and outcomes of both treatments.

Interactive simulator for e-Learning environments: a teaching software for health care professionals.

PubMed

De Lazzari, Claudio; Genuini, Igino; Pisanelli, Domenico M; D'Ambrosi, Alessandra; Fedele, Francesco

2014-12-18

There is an established tradition of cardiovascular simulation tools, but the application of this kind of technology in the e-Learning arena is a novel approach. This paper presents an e-Learning environment aimed at teaching the interaction of cardiovascular and lung systems to health-care professionals. Heart-lung interaction must be analyzed while assisting patients with severe respiratory problems or with heart failure in intensive care unit. Such patients can be assisted by mechanical ventilatory assistance or by thoracic artificial lung."In silico" cardiovascular simulator was experimented during a training course given to graduate students of the School of Specialization in Cardiology at 'Sapienza' University in Rome.The training course employed CARDIOSIM©: a numerical simulator of the cardiovascular system. Such simulator is able to reproduce pathophysiological conditions of patients affected by cardiovascular and/or lung disease. In order to study the interactions among the cardiovascular system, the natural lung and the thoracic artificial lung (TAL), the numerical model of this device has been implemented. After having reproduced a patient's pathological condition, TAL model was applied in parallel and hybrid model during the training course.Results obtained during the training course show that TAL parallel assistance reduces right ventricular end systolic (diastolic) volume, but increases left ventricular end systolic (diastolic) volume. The percentage changes induced by hybrid TAL assistance on haemodynamic variables are lower than those produced by parallel assistance. Only in the case of the mean pulmonary arterial pressure, there is a percentage reduction which, in case of hybrid assistance, is greater (about 40%) than in case of parallel assistance (20-30%).At the end of the course, a short questionnaire was submitted to students in order to assess the quality of the course. The feedback obtained was positive, showing good results with respect to the degree of students' learning and the ease of use of the software simulator.

Assessment and monitoring of flow limitation and other parameters from flow/volume loops.

PubMed

Dueck, R

2000-01-01

Flow/volume (F/V) spirometry is routinely used for assessing the type and severity of lung disease. Forced vital capacity (FVC) and timed vital capacity (FEV1) provide the best estimates of airflow obstruction in patients with asthma, chronic obstructive pulmonary disease (COPD) and emphysema. Computerized spirometers are now available for early home recognition of asthma exacerbation in high risk patients with severe persistent disease, and for recognition of either infection or rejection in lung transplant patients. Patients with severe COPD may exhibit expiratory flow limitation (EFL) on tidal volume (VT) expiratory F/V (VTF/V) curves, either with or without applying negative expiratory pressure (NEP). EFL results in dynamic hyperinflation and persistently raised alveolar pressure or intrinsic PEEP (PEEPi). Hyperinflation and raised PEEPi greatly enhance dyspnea with exertion through the added work of the threshold load needed to overcome raised pleural pressure. Esophageal (pleural) pressure monitoring may be added to VTF/V loops for assessing the severity of PEEPi: 1) to optimize assisted ventilation by mask or via endotracheal tube with high inspiratory flow rates to lower I:E ratio, and 2) to assess the efficacy of either pressure support ventilation (PSV) or low level extrinsic PEEP in reducing the threshold load of PEEPi. Intraoperative tidal volume F/V loops can also be used to document the efficacy of emphysema lung volume reduction surgery (LVRS) via disappearance of EFL. Finally, the mechanism of ventilatory constraint can be identified with the use of exercise tidal volume F/V loops referenced to maximum F/V loops and static lung volumes. Patients with severe COPD show inspiratory F/V loops approaching 95% of total lung capacity, and flow limitation over the entire expiratory F/V curve during light levels of exercise. Surprisingly, patients with a history of congestive heart failure may lower lung volume towards residual volume during exercise, thereby reducing airway diameter and inducing expiratory flow limitation.

The evolution of endothermy in terrestrial vertebrates: Who? When? Why?

PubMed

Hillenius, Willem J; Ruben, John A

2004-01-01

Avian and mammalian endothermy results from elevated rates of resting, or routine, metabolism and enables these animals to maintain high and stable body temperatures in the face of variable ambient temperatures. Endothermy is also associated with enhanced stamina and elevated capacity for aerobic metabolism during periods of prolonged activity. These attributes of birds and mammals have greatly contributed to their widespread distribution and ecological success. Unfortunately, since few anatomical/physiological attributes linked to endothermy are preserved in fossils, the origin of endothermy among the ancestors of mammals and birds has long remained obscure. Two recent approaches provide new insight into the metabolic physiology of extinct forms. One addresses chronic (resting) metabolic rates and emphasizes the presence of nasal respiratory turbinates in virtually all extant endotherms. These structures are associated with recovery of respiratory heat and moisture in animals with high resting metabolic rates. The fossil record of nonmammalian synapsids suggests that at least two Late Permian lineages possessed incipient respiratory turbinates. In contrast, these structures appear to have been absent in dinosaurs and nonornithurine birds. Instead, nasal morphology suggests that in the avian lineage, respiratory turbinates first appeared in Cretaceous ornithurines. The other approach addresses the capacity for maximal aerobic activity and examines lung structure and ventilatory mechanisms. There is no positive evidence to support the reconstruction of a derived, avian-like parabronchial lung/air sac system in dinosaurs or nonornithurine birds. Dinosaur lungs were likely heterogenous, multicameral septate lungs with conventional, tidal ventilation, although evidence from some theropods suggests that at least this group may have had a hepatic piston mechanism of supplementary lung ventilation. This suggests that dinosaurs and nonornithurine birds generally lacked the capacity for high, avian-like levels of sustained activity, although the aerobic capacity of theropods may have exceeded that of extant ectotherms. The avian parabronchial lung/air sac system appears to be an attribute limited to ornithurine birds.

Mechanical ventilation with high tidal volume induces inflammation in patients without lung disease.

PubMed

Pinheiro de Oliveira, Roselaine; Hetzel, Marcio Pereira; dos Anjos Silva, Mauro; Dallegrave, Daniele; Friedman, Gilberto

2010-01-01

Mechanical ventilation (MV) with high tidal volumes may induce or aggravate lung injury in critical ill patients. We compared the effects of a protective versus a conventional ventilatory strategy, on systemic and lung production of tumor necrosis factor-alpha (TNF-alpha) and interleukin-8 (IL-8) in patients without lung disease. Patients without lung disease and submitted to mechanical ventilation admitted to one trauma and one general adult intensive care unit of two different university hospitals were enrolled in a prospective randomized-control study. Patients were randomized to receive MV either with tidal volume (VT) of 10 to 12 ml/kg predicted body weight (high VT group) (n = 10) or with VT of 5 to 7 ml/kg predicted body weight (low VT group) (n = 10) with an oxygen inspiratory fraction (FIO2) enough to keep arterial oxygen saturation >90% with positive end-expiratory pressure (PEEP) of 5 cmH2O during 12 hours after admission to the study. TNF-alpha and IL-8 concentrations were measured in the serum and in the bronchoalveolar lavage fluid (BALF) at admission and after 12 hours of study observation time. Twenty patients were enrolled and analyzed. At admission or after 12 hours there were no differences in serum TNF-alpha and IL-8 between the two groups. While initial analysis did not reveal significant differences, standardization against urea of logarithmic transformed data revealed that TNF-alpha and IL-8 levels in bronchoalveolar lavage (BAL) fluid were stable in the low VT group but increased in the high VT group (P = 0.04 and P = 0.03). After 12 hours, BALF TNF-alpha (P = 0.03) and BALF IL-8 concentrations (P = 0.03) were higher in the high VT group than in the low VT group. The use of lower tidal volumes may limit pulmonary inflammation in mechanically ventilated patients even without lung injury. NCT00935896.

Effects of nasal positive expiratory pressure on dynamic hyperinflation and 6-minute walk test in patients with COPD.

PubMed

Wibmer, Thomas; Rüdiger, Stefan; Heitner, Claudia; Kropf-Sanchen, Cornelia; Blanta, Ioanna; Stoiber, Kathrin M; Rottbauer, Wolfgang; Schumann, Christian

2014-05-01

Dynamic hyperinflation is an important target in the treatment of COPD. There is increasing evidence that positive expiratory pressure (PEP) could reduce dynamic hyperinflation during exercise. PEP application through a nasal mask and a flow resistance device might have the potential to be used during daily physical activities as an auxiliary strategy of ventilatory assistance. The aim of this study was to determine the effects of nasal PEP on lung volumes during physical exercise in patients with COPD. Twenty subjects (mean ± SD age 69.4 ± 6.4 years) with stable mild-to-severe COPD were randomized to undergo physical exercise with nasal PEP breathing, followed by physical exercise with habitual breathing, or vice versa. Physical exercise was induced by a standard 6-min walk test (6 MWT) protocol. PEP was applied by means of a silicone nasal mask loaded with a fixed-orifice flow resistor. Body plethysmography was performed immediately pre-exercise and post-exercise. Differences in mean pre- to post-exercise changes in total lung capacity (-0.63 ± 0.80 L, P = .002), functional residual capacity (-0.48 ± 0.86 L, P = .021), residual volume (-0.56 ± 0.75 L, P = .004), S(pO2) (-1.7 ± 3.4%, P = .041), and 6 MWT distance (-30.8 ± 30.0 m, P = .001) were statistically significant between the experimental and the control interventions. The use of flow-dependent expiratory pressure, applied with a nasal mask and a PEP device, might promote significant reduction of dynamic hyperinflation during walking exercise. Further studies are warranted addressing improvements in endurance performance under regular application of nasal PEP during physical activities.

Minocycline blocks glial cell activation and ventilatory acclimatization to hypoxia.

PubMed

Stokes, Jennifer A; Arbogast, Tara E; Moya, Esteban A; Fu, Zhenxing; Powell, Frank L

2017-04-01

Ventilatory acclimatization to hypoxia (VAH) is the time-dependent increase in ventilation, which persists upon return to normoxia and involves plasticity in both central nervous system respiratory centers and peripheral chemoreceptors. We investigated the role of glial cells in VAH in male Sprague-Dawley rats using minocycline, an antibiotic that inhibits microglia activation and has anti-inflammatory properties, and barometric pressure plethysmography to measure ventilation. Rats received either minocycline (45mg/kg ip daily) or saline beginning 1 day before and during 7 days of chronic hypoxia (CH, Pi O 2  = 70 Torr). Minocycline had no effect on normoxic control rats or the hypercapnic ventilatory response in CH rats, but minocycline significantly ( P < 0.001) decreased ventilation during acute hypoxia in CH rats. However, minocycline administration during only the last 3 days of CH did not reverse VAH. Microglia and astrocyte activation in the nucleus tractus solitarius was quantified from 30 min to 7 days of CH. Microglia showed an active morphology (shorter and fewer branches) after 1 h of hypoxia and returned to the control state (longer filaments and extensive branching) after 4 h of CH. Astrocytes increased glial fibrillary acidic protein antibody immunofluorescent intensity, indicating activation, at both 4 and 24 h of CH. Minocycline had no effect on glia in normoxia but significantly decreased microglia activation at 1 h of CH and astrocyte activation at 24 h of CH. These results support a role for glial cells, providing an early signal for the induction but not maintenance of neural plasticity underlying ventilatory acclimatization to hypoxia. NEW & NOTEWORTHY The signals for neural plasticity in medullary respiratory centers underlying ventilatory acclimatization to chronic hypoxia are unknown. We show that chronic hypoxia activates microglia and subsequently astrocytes. Minocycline, an antibiotic that blocks microglial activation and has anti-inflammatory properties, also blocks astrocyte activation in respiratory centers during chronic hypoxia and ventilatory acclimatization. However, minocycline cannot reverse ventilatory acclimatization after it is established. Hence, glial cells may provide signals that initiate but do not sustain ventilatory acclimatization. Copyright © 2017 the American Physiological Society.

Minocycline blocks glial cell activation and ventilatory acclimatization to hypoxia

PubMed Central

Arbogast, Tara E.; Moya, Esteban A.; Fu, Zhenxing; Powell, Frank L.

2017-01-01

Ventilatory acclimatization to hypoxia (VAH) is the time-dependent increase in ventilation, which persists upon return to normoxia and involves plasticity in both central nervous system respiratory centers and peripheral chemoreceptors. We investigated the role of glial cells in VAH in male Sprague-Dawley rats using minocycline, an antibiotic that inhibits microglia activation and has anti-inflammatory properties, and barometric pressure plethysmography to measure ventilation. Rats received either minocycline (45mg/kg ip daily) or saline beginning 1 day before and during 7 days of chronic hypoxia (CH, PiO2 = 70 Torr). Minocycline had no effect on normoxic control rats or the hypercapnic ventilatory response in CH rats, but minocycline significantly (P < 0.001) decreased ventilation during acute hypoxia in CH rats. However, minocycline administration during only the last 3 days of CH did not reverse VAH. Microglia and astrocyte activation in the nucleus tractus solitarius was quantified from 30 min to 7 days of CH. Microglia showed an active morphology (shorter and fewer branches) after 1 h of hypoxia and returned to the control state (longer filaments and extensive branching) after 4 h of CH. Astrocytes increased glial fibrillary acidic protein antibody immunofluorescent intensity, indicating activation, at both 4 and 24 h of CH. Minocycline had no effect on glia in normoxia but significantly decreased microglia activation at 1 h of CH and astrocyte activation at 24 h of CH. These results support a role for glial cells, providing an early signal for the induction but not maintenance of neural plasticity underlying ventilatory acclimatization to hypoxia. NEW & NOTEWORTHY The signals for neural plasticity in medullary respiratory centers underlying ventilatory acclimatization to chronic hypoxia are unknown. We show that chronic hypoxia activates microglia and subsequently astrocytes. Minocycline, an antibiotic that blocks microglial activation and has anti-inflammatory properties, also blocks astrocyte activation in respiratory centers during chronic hypoxia and ventilatory acclimatization. However, minocycline cannot reverse ventilatory acclimatization after it is established. Hence, glial cells may provide signals that initiate but do not sustain ventilatory acclimatization. PMID:28100653

Effect of pyridostigmine on in vivo and in vitro respiratory muscle of mdx mice.

PubMed

Amancio, Gabriela de Cássia Sousa; Grabe-Guimarães, Andrea; Haikel, Dridi; Moreau, Johan; Barcellos, Neila Marcia Silva; Lacampagne, Alain; Matecki, Stefan; Cazorla, Olivier

2017-09-01

The current work was conducted to verify the contribution of neuromuscular transmission defects at the neuromuscular junction to Duchenne Muscular Dystrophy disease progression and respiratory dysfunction. We tested pyridostigmine and pyridostigmine encapsulated in liposomes (liposomal PYR), an acetylcholinesterase inhibitor to improve muscular contraction on respiratory muscle function in mdx mice at different ages. We evaluated in vivo with the whole-body plethysmography, the ventilatory response to hypercapnia, and measured in vitro diaphragm strength in each group. Compared to C57BL10 mice, only 17 and 22 month-old mdx presented blunted ventilatory response, under normocapnia and hypercapnia. Free pyridostigmine (1mg/kg) was toxic to mdx mice, unlike liposomal PYR, which did not show any side effect, confirming that the encapsulation in liposomes is effective in reducing the toxic effects of this drug. Treatment with liposomal PYR, either acute or chronic, did not show any beneficial effect on respiratory function of this DMD experimental model. The encapsulation in liposomes is effective to abolish toxic effects of drugs. Copyright © 2017. Published by Elsevier B.V.

Ibuprofen does not reverse ventilatory acclimatization to chronic hypoxia.

PubMed

De La Zerda, D J; Stokes, J A; Do, J; Go, A; Fu, Z; Powell, F L

2017-07-27

Ventilatory acclimatization to hypoxia involves an increase in the acute hypoxic ventilatory response that is blocked by non-steroidal anti-inflammatory drugs administered during sustained hypoxia. We tested the hypothesis that inflammatory signals are necessary to sustain ventilatory acclimatization to hypoxia once it is established. Adult, rats were acclimatized to normoxia or chronic hypoxia (CH, [Formula: see text] =70Torr) for 11-12days and treated with ibuprofen or saline for the last 2days of hypoxia. Ventilation, metabolic rate, and arterial blood gas responses to O 2 and CO 2 were not affected by ibuprofen after acclimatization had been established. Immunohistochemistry and image analysis showed acute (1h) hypoxia activated microglia in a medullary respiratory center (nucleus tractus solitarius, NTS) and this was blocked by ibuprofen administered from the beginning of hypoxic exposure. Microglia returned to the control state after 7days of CH and were not affected by ibuprofen administered for 2 more days of CH. In contrast, NTS astrocytes were activated by CH but not acute hypoxia and activation was not reversed by administering ibuprofen for the last 2days of CH. Hence, ibuprofen cannot reverse ventilatory acclimatization or astrocyte activation after they have been established by sustained hypoxia. The results are consistent with a model for microglia activation or other ibuprofen-sensitive processes being necessary for the induction but not maintenance of ventilatory acclimatization to hypoxia. Copyright © 2017 Elsevier B.V. All rights reserved.

Performance of heated humidifiers with a heated wire according to ventilatory settings.

PubMed

Nishida, T; Nishimura, M; Fujino, Y; Mashimo, T

2001-01-01

Delivering warm, humidified gas to patients is important during mechanical ventilation. Heated humidifiers are effective and popular. The humidifying efficiency is influenced not only by performance and settings of the devices but the settings of ventilator. We compared the efficiency of humidifying devices with a heated wire and servo-controlled function under a variety of ventilator settings. A bench study was done with a TTL model lung. The study took place in the laboratory of the University Hospital, Osaka, Japan. Four devices (MR290 with MR730, MR310 with MR730; both Fisher & Paykel, ConchaTherm IV; Hudson RCI, and HummaxII; METRAN) were tested. Hummax II has been developed recently, and it consists of a heated wire and polyethylene microporous hollow fiber. Both wire and fiber were put inside of an inspiratory circuit, and water vapor is delivered throughout the circuit. The Servo 300 was connected to the TTL with a standard ventilator circuit. The ventilator settings were as follows; minute ventilation (V(E)) 5, 10, and 15 L/min, a respiratory rate of 10 breaths/min, I:E ratio 1:1, 1:2, and 1:4, and no applied PEEP. Humidifying devices were set to maintain the temperature of airway opening at 32 degrees C and 37 degrees C. The greater V(E) the lower the humidity with all devices except Hummax II. Hummax II delivered 100% relative humidity at all ventilator and humidifier settings. When airway temperature control of the devices was set at 32 degrees C, the ConchaTherm IV did not deliver 30 mg/L of vapor, which is the value recommended by American National Standards at all V(E) settings. At 10 and 15 L/min of V(E) settings MR310 with MR730 did not deliver recommended vapor, either. In conclusion, airway temperature setting of the humidifying devices influenced the humidity of inspiratory gas greatly. Ventilatory settings also influenced the humidity of inspiratory gas. The Hummax II delivered sufficient water vapor under a variety of minute ventilation.

Forced vital capacity and not central chemoreflex predicts maximal hyperoxic breath-hold duration in elite apneists.

PubMed

Bain, Anthony R; Barak, Otto F; Hoiland, Ryan L; Drvis, Ivan; Bailey, Damian M; Dujic, Zeljko; Mijacika, Tanja; Santoro, Antoinette; DeMasi, Daniel K; MacLeod, David B; Ainslie, Philip N

2017-08-01

The determining mechanisms of a maximal hyperoxic apnea duration in elite apneists have remained unexplored. We tested the hypothesis that maximal hyperoxic apnea duration in elite apneists is related to forced vital capacity (FVC) but not the central chemoreflex (for CO 2 ). Eleven elite apneists performed a maximal dry static-apnea with prior hyperoxic (100% oxygen) pre-breathing, and a central chemoreflex test via a hyperoxic re-breathing technique (hyperoxic-hypercapnic ventilatory response: HCVR); expressed as the increase in ventilation (pneumotachometry) per increase in arterial CO 2 tension (PaCO 2 ; radial artery). FVC was assessed using standard spirometry. Maximal apnea duration ranged from 807 to 1262s (mean=1034s). Average HCVR was 2.0±1.2Lmin -1 mmHg -1 PaCO 2 . The hyperoxic apnea duration was related to the FVC (r 2 =0.45, p<0.05), but not the HCVR (r 2 <0.01, p>0.05). These findings were interpreted to suggest that during a hyperoxic apnea, a larger initial lung volume prolongs the time before reaching intolerable discomfort associated with pending lung squeeze, while CO 2 sensitivity has little impact. Copyright © 2017 Elsevier B.V. All rights reserved.

19th century pioneering of intensive therapy in North America. Part 3: the Fell-O'Dwyer apparatus and William P Northrup.

PubMed

Trubuhovich, Ronald V

2009-03-01

Two previous articles in this series have described the reintroduction of forced respiration for ventilatory difficulties, particularly in opiate poisoning (by George Fell), and successful use of intralaryngeal tubes designed for treating airway obstruction in diphtheritic acute laryngitis (by Joseph O'Dwyer). In 1891, O'Dwyer extended the applications of Fell's system, introducing a longer orolaryngeal tube, replacing Fell's methods of inflating the lungs, which had been with a somewhat unsatisfactory facemask or through a tracheotomy tube. The combined system became known as the "Fell-O'Dwyer apparatus". Use of the apparatus widened, to include treating apnoea from intracranial disasters (by William P Northrup, especially) and, on the initiative of Rudolph Matas, in delivering anaesthesia and maintaining lung inflation to enable intrathoracic surgery (by FW Parham). Although the apparatus was used beyond New York (eg, in New Orleans by J D Bloom, especially for neonatal apnoea), it is difficult to find other than nonspecific references. Matas and Bloom improved O'Dwyer's original system, but after the clinical success of Charles Elsberg's continuous insufflation anaesthesia for thoracic surgery, 1909, American anaesthetists came to prefer that.

Role of upper airway in ventilatory control in awake and sleeping dogs.

PubMed

Stradling, J R; England, S J; Harding, R; Kozar, L F; Andrey, S; Phillipson, E A

1987-03-01

We examined the role of the upper airway in the regulation of the pattern of breathing in six adult dogs during wakefulness and sleep. The dogs breathed through a fenestrated endotracheal tube inserted through a tracheostomy. The tube was modified to allow airflow to be directed either through the nose or through the tracheostomy. When airflow was diverted from nose to tracheostomy there was an abrupt increase in the rate of expiratory airflow, resulting in prolongation of the end-expiratory pause but no change in overall expiratory duration or respiratory frequency. Furthermore, electromyogram recordings from implanted diaphragmatic and laryngeal muscle electrodes did not show any changes that could be interpreted as an attempt to delay expiratory airflow or increase end-expiratory lung volume. The effects of switching from nose to tracheostomy breathing could be reversed by adding a resistance to the endotracheal tube so as to approximate upper airway resistance. The findings indicate that under normal conditions in the adult dog upper airway receptors play little role in regulation of respiratory pattern and that the upper airway exerts little influence on the maintenance of end-expiratory lung volume.

Short-Term Modulation of the Ventilatory Response to Exercise is Preserved in Obstructive Sleep Apnea

PubMed Central

Bernhardt, Vipa; Mitchell, Gordon S.; Lee, Won Y.; Babb, Tony G.

2016-01-01

Background The ventilatory response to exercise can be transiently adjusted in response to environmentally (e.g., breathing apparatus) or physiologically altered conditions (e.g., respiratory disease), maintaining constant relative arterial PCO2 regulation from rest to exercise (Mitchell and Babb, 2006); this augmentation is called short-term modulation (STM) of the exercise ventilatory response. Obesity and/or obstructive sleep apnea could affect the exercise ventilatory response and the capacity for STM due to chronically increased mechanical and/or ventilatory loads on the respiratory system, and/or recurrent (chronic) intermittent hypoxia experienced during sleep. We hypothesized that: 1) the exercise ventilatory response is augmented in obese OSA patients compared with obese non-OSA adults, and 2) the capacity for STM with added dead space is diminished in obese OSA patients. Methods Nine obese adults with OSA (age: 39 ± 6 yr, BMI: 40 ± 5 kg/m2, AHI: 25 ± 24 events/hr [range 6–73], mean ± SD) and 8 obese adults without OSA (age: 38 ± 10 yr, BMI: 37 ± 6 kg/m2, AHI: 1 ± 2) completed three, 20-min bouts of constant-load submaximal cycling exercise (8 min rest, 6 min at 10 and 30 W) with or without added external dead space (200 or 400 ml; 20 min rest between bouts). Steady-state measurements were made of ventilation (V̇E), oxygen consumption (V̇O2), carbon dioxide production (V̇CO2), and end-tidal PCO2 (PETCO2). The exercise ventilatory response was defined as the slope of the V̇E-V̇CO2 relationship (ΔV̇E/ΔV̇CO2). Results In control (i.e. no added dead space), the exercise ventilatory response was not significantly different between non-OSA and OSA groups (ΔV̇E/ΔV̇CO2 slope: 30.5 ± 4.2 vs 30.5 ± 3.8, p > 0.05); PETCO2 regulation from rest to exercise did not differ between groups (p > 0.05). In trials with added external dead space, ΔV̇E/ΔV̇CO2 increased with increased dead space (p < 0.05) and the PETCO2 change from rest to exercise remained small (<2 mmHg) in both groups, demonstrating STM. There were no significant differences between groups. Conclusions Contrary to our hypotheses: 1) the exercise ventilatory response is not increased in obese OSA patients compared with obese non-OSA adults, and 2) the capacity for STM with added dead space is preserved in obese OSA and non-OSA adults. PMID:27840272

Ventilatory acclimatization to hypoxia in mice: Methodological considerations.

PubMed

Ivy, Catherine M; Scott, Graham R

2017-01-01

We examined ventilatory acclimatization to hypoxia (VAH) in CD1 mice, and contrasted results obtained using the barometric method on unrestrained mice with pneumotachography and pulse oximetry on restrained mice. Responses to progressive step reductions in O 2 fraction (21%-8%) were assessed in mice acclimated to normoxia and hypobaric hypoxia (barometric pressure of 60kPa for 6-8 weeks). Hypoxia acclimation increased the hypoxic ventilatory response (primarily by increasing breathing frequency rather than tidal volume), arterial O 2 saturation (Sa O2 ) and heart rate in deep hypoxia, hypoxic chemosensitivity (ventilatory O 2 /CO 2 equivalents versus Sa O2 ), and respiratory water loss, and it blunted the hypoxic depression of metabolism and body temperature. Although some effects of hypoxia acclimation were qualitatively similar between methods, the effects were often greater in magnitude when assessed using pneumotachography. Furthermore, whereas hypoxia acclimation reduced ventilatory O 2 equivalent and increased pulmonary O 2 extraction in barometric experiments, it had the opposite effects in pneumotachography experiments. Our findings highlight the importance of considering the impact of how breathing is measured on the apparent responses to hypoxia. Copyright © 2016 Elsevier B.V. All rights reserved.

Cardiopulmonary Exercise Testing in Adult Congenital Heart Disease.

PubMed

Mantegazza, Valentina; Apostolo, Anna; Hager, Alfred

2017-07-01

Recently, the number of patients with congenital heart diseases reaching adulthood has been progressively increasing in developed countries, and new issues are emerging: the evaluation of their capacity to cope with physical activity and whether this knowledge can be used to optimize medical management. A symptom-limited cardiopulmonary exercise test has proven to be an essential tool, because it can objectively evaluate the functional cardiovascular capacity of these patients, identify the pathological mechanisms of the defect (circulatory failure, shunts, and/or pulmonary hypertension), and help prescribe an individualized rehabilitation program when needed. The common findings on cardiopulmonary exercise testing in patients with congenital heart diseases are a reduced peak [Formula: see text]o 2 , an early anaerobic threshold, a blunted heart rate response, a reduced increase of Vt, and an increased [Formula: see text]e/[Formula: see text]co 2 . All these measures suggest common pathophysiological abnormalities: (1) a compromised exercise capacity from anomalies affecting the heart, vessels, lungs, or muscles; (2) chronotropic incompetence secondary to cardiac autonomic dysfunction or β-blockers and antiarrhythmic therapy; and (3) ventilatory inefficiency caused by left-heart failure with pulmonary congestion, pulmonary hypertension, pulmonary obstructive vascular disease, or cachexia. Most of these variables also have prognostic significance. For these patients, cardiopulmonary exercise testing allows evaluation and decisions affecting lifestyle and therapeutic interventions.

Fluoxetine augments ventilatory CO2 sensitivity in Brown Norway but not Sprague Dawley rats.

PubMed

Hodges, Matthew R; Echert, Ashley E; Puissant, Madeleine M; Mouradian, Gary C

2013-04-01

The Brown Norway (BN; BN/NHsdMcwi) rat exhibits a deficit in ventilatory CO2 sensitivity and a modest serotonin (5-HT) deficiency. Here, we tested the hypothesis that the selective serotonin reuptake inhibitor fluoxetine would augment CO2 sensitivity in BN but not Sprague Dawley (SD) rats. Ventilation during room air or 7% CO2 exposure was measured before, during and after 3 weeks of daily injections of saline or fluoxetine (10mg/(kgday)) in adult male BN and SD rats. Fluoxetine had minimal effects on room air breathing in BN and SD rats (p>0.05), although tidal volume (VT) was reduced in BN rats (p<0.05). There were also minimal effects of fluoxetine on CO2 sensitivity in SD rats, but fluoxetine increased minute ventilation, breathing frequency and VT during hypercapnia in BN rats (p<0.05). The augmented CO2 response was reversible upon withdrawal of fluoxetine. Brain levels of biogenic amines were largely unaffected, but 5-HIAA and the ratio of 5-HIAA/5-HT were reduced (p<0.05) consistent with selective and effective 5-HT reuptake inhibition. Thus, fluoxetine increases ventilatory CO2 sensitivity in BN but not SD rats, further suggesting altered 5-HT system function may contribute to the inherently low CO2 sensitivity in the BN rat. Copyright © 2013 Elsevier B.V. All rights reserved.

Physical interactions of hyperpolarized gas in the lung

NASA Astrophysics Data System (ADS)

Chen, Xiu-Hao Josette

1999-09-01

This thesis addresses key interactions of hyperpolarized (HP) gas within the biological environment of the lung using magnetic resonance imaging (MRI). The first excised lung image was obtained in 1994 by Albert et al ., indicating the relative youth of the HP gas MRI field. Thus, there are a multitude of parameters which need to be explored to optimize contrast mechanisms and pulse sequences for in vivo applications. To perform HP gas MRI, both the production of HP gas and development of appropriate MRI pulse sequences were necessary. The apparatus for gas polarization was transferred from Princeton University, then modified and optimized to provide larger quantities and higher polarizations. It was ultimately replaced by a prototype commercial apparatus. Existing MRI pulse sequences were changed to accommodate and exploit the unique situation of non-equilibrium polarized gas. Several physical parameters of the gas relating to structure and function in the lung were investigated. It was found that using a range of excitation powers, acquisition windows, and ventilatory cycle segments yielded dramatically different types of images in the guinea pig. Spatially localized lineshapes of HP 3He showed differentiated peaks (corresponding to frequency shifts) which represent gas in major airways (2 ppm) and alveoli (1-2 ppm). Quantitative maps of the diffusion coefficient (D) showed evidence of free diffusion in the trachea (average of 2.4 cm2/s for 3He and 0.68 cm2/s for 129Xe) and restricted diffusion combined with effects of gas mixtures in the distal pulmonary airspaces (average of 0.16 cm2/s for 3He and 0.021 cm2/s for 129Xe). Experimental measurements were verified with gas mixture and porous media theory for both 3He and 129Xe. The dephasing parameter, T*2 , was mapped showing sensitivity to changes in tidal volume and oxygen level. The T*2 values ranged from 9.2 to 15.9 ms in the intrapulmonary airspaces depending on the breathing paradigm. Experimental results were confirmed with porous media theory. Finally, the technique of D measurement was applied in a disease model. The histograms of D at end expiratory volume and 2 mL tidal volume held breath were shown to exhibit a significant shift in a healthy rat, but not in an elastase-induced (a model for emphysema) rat.

Low-dose morphine elicits ventilatory excitant and depressant responses in conscious rats: Role of peripheral μ-opioid receptors.

PubMed

Henderson, Fraser; May, Walter J; Gruber, Ryan B; Young, Alex P; Palmer, Lisa A; Gaston, Benjamin; Lewis, Stephen J

2013-08-01

The systemic administration of morphine affects ventilation via a mixture of central and peripheral actions. The aims of this study were to characterize the ventilatory responses elicited by a low dose of morphine in conscious rats; to determine whether tolerance develops to these responses; and to determine the potential roles of peripheral μ-opioid receptors (μ-ORs) in these responses. Ventilatory parameters were monitored via unrestrained whole-body plethysmography. Conscious male Sprague-Dawley rats received an intravenous injection of vehicle or the peripherally-restricted μ-OR antagonist, naloxone methiodide (NLXmi), and then three successive injections of morphine (1 mg/kg) given 30 min apart. The first injection of morphine in vehicle-treated rats elicited an array of ventilatory excitant (i.e., increases in frequency of breathing, minute volume, respiratory drive, peak inspiratory and expiratory flows, accompanied by decreases in inspiratory time and end inspiratory pause) and inhibitory (i.e., a decrease in tidal volume and an increase in expiratory time) responses. Subsequent injections of morphine elicited progressively and substantially smaller responses. The pattern of ventilatory responses elicited by the first injection of morphine was substantially affected by pretreatment with NLXmi whereas NLXmi minimally affected the development of tolerance to these responses. Low-dose morphine elicits an array of ventilatory excitant and depressant effects in conscious rats that are subject to the development of tolerance. Many of these initial actions of morphine appear to involve activation of peripheral μ-ORs whereas the development of tolerance to these responses does not.

Ventilatory inhomogeneity determined from multiple-breath washouts during sustained microgravity on Spacelab SLS-1.

PubMed

Prisk, G K; Guy, H J; Elliott, A R; Paiva, M; West, J B

1995-02-01

We used multiple-breath N2 washouts (MBNW) to study the inhomogeneity of ventilation in four normal humans (mean age 42.5 yr) before, during, and after 9 days of exposure to microgravity on Spacelab Life Sciences-1. Subjects performed 20-breath MBNW at tidal volumes of approximately 700 ml and 12-breath MBNW at tidal volumes of approximately 1,250 ml. Six indexes of ventilatory inhomogeneity were derived from data from 1) distribution of specific ventilation (SV) from mixed-expired and 2) end-tidal N2, 3) change of slope of N2 washout (semilog plot) with time, 4) change of slope of normalized phase III of successive breaths, 5) anatomic dead space, and 6) Bohr dead space. Significant ventilatory inhomogeneity was seen in the standing position at normal gravity (1 G). When we compared standing 1 G with microgravity, the distributions of SV became slightly narrower, but the difference was not significant. Also, there were no significant changes in the change of slope of the N2 washout, change of normalized phase III slopes, or the anatomic and Bohr dead spaces. By contrast, transition from the standing to supine position in 1 G resulted in significantly broader distributions of SV (P < 0.05) and significantly greater changes in the changes in slope of the N2 washouts (P < 0.001), indicating more ventilatory inhomogeneity in that posture. Thus these techniques can detect relatively small changes in ventilatory inhomogeneity. We conclude that the primary determinants of ventilatory inhomogeneity during tidal breathing in the upright posture are not gravitational in origin.

Ageing and cardiorespiratory response to hypoxia.

PubMed

Lhuissier, François J; Canouï-Poitrine, Florence; Richalet, Jean-Paul

2012-11-01

The risk of severe altitude-induced diseases is related to ventilatory and cardiac responses to hypoxia and is dependent on sex, age and exercise training status. However, it remains unclear how ageing modifies these physiological adaptations to hypoxia. We assessed the physiological responses to hypoxia with ageing through a cross-sectional 20 year study including 4675 subjects (2789 men, 1886 women; 14-85 years old) and a longitudinal study including 30 subjects explored at a mean 10.4 year interval. The influence of sex, training status and menopause was evaluated. The hypoxia-induced desaturation and the ventilatory and cardiac responses to hypoxia at rest and exercise were measured. In men, ventilatory response to hypoxia increased (P < 0.002), while desaturation was less pronounced (P < 0.001) with ageing. Cardiac response to hypoxia was blunted with ageing in both sexes (P < 0.001). Similar results were found in the longitudinal study, with a decrease in cardiac and an increase in ventilatory response to hypoxia with ageing. These adaptive responses were less pronounced or absent in post-menopausal women (P < 0.01). At exercise, desaturation was greater in trained subjects but cardiac and ventilatory responses to hypoxia were preserved by training, especially in elderly people. In conclusion, respiratory response to hypoxia and blood oxygenation improve with ageing in men while cardiac response is blunted with ageing in both sexes. Training aggravates desaturation at exercise in hypoxia, improves the ventilatory response and limits the ageing-induced blunting of cardiac response to hypoxia. Training limits the negative effects of menopause in cardiorespiratory adaptations to hypoxia.

Ventilatory response to hypercarbia in newborns of smoking and substance-misusing mothers.

PubMed

Ali, Kamal; Wolff, Kim; Peacock, Janet L; Hannam, Simon; Rafferty, Gerrard F; Bhat, Ravindra; Greenough, Anne

2014-07-01

Infants of mothers who smoked (S) or substance misused (SM) during pregnancy have an increased risk of sudden infant death syndrome (SIDS). To test the hypothesis that infants of S and SM mothers compared with infants of non-substance-misusing, nonsmoking mothers (control subjects) would have a reduced ventilatory response to hypercarbia and that any reduction would be greater in the SM infants. Infants were assessed before maternity/neonatal unit discharge. Maternal and infant urine samples were obtained and tested for cotinine, cannabinoids, opiates, amphetamines, methadone, cocaine, and benzodiazepines. Respiratory flow and Vt were measured using a pneumotachograph inserted into a face mask placed over the infant's mouth and nose. The ventilatory responses to three levels of inspired carbon dioxide (0 [baseline], 2, and 4% CO2) were assessed. Twenty-three SM, 34 S, and 22 control infants were assessed. The birth weight of the control subjects was higher than the SM and S infants (P = 0.017). At baseline, SM infants had a higher respiratory rate (P = 0.003) and minute volume (P = 0.007) compared with control subjects and S infants. Both the SM and S infants had a lower ventilatory response to 2% (P < 0.001) and 4% (P < 0.001) CO2 than the control subjects. The ventilatory response to CO2 was lower in the SM infants compared with the S infants (P = 0.009). These results are consistent with infants of smoking mothers and substance misuse/smoking mothers having a dampened ventilatory response to hypercarbia, which is particularly marked in the latter group.

Chest tube drainage of transudative pleural effusions hastens liberation from mechanical ventilation.

PubMed

Kupfer, Yizhak; Seneviratne, Chanaka; Chawla, Kabu; Ramachandran, Kavan; Tessler, Sidney

2011-03-01

Pleural effusions occur frequently in patients requiring mechanical ventilatory support. Treatment of the precipitating cause and resolution of the pleural effusion may take considerable time. We retrospectively studied the effect of chest tube drainage of transudative pleural effusions on the liberation of patients from mechanical ventilatory support. Patients in the medical ICU (MICU) at Maimonides Medical Center between January 1, 2009, and October 31, 2009, requiring mechanical ventilatory support with a transudative pleural effusion, were studied retrospectively. They were divided into two groups: standard care and standard care plus chest tube drainage. Chest tubes were placed under ultrasound guidance by trained intensivists. Duration of mechanical ventilatory support was the primary end point. Secondary end points included measures of oxygenation, amount of fluid drained, and complications associated with the chest tube. A total of 168 patients were studied; 88 were treated with standard care and 80 underwent chest tube drainage. Total duration of mechanical ventilatory support was significantly shorter for patients who had chest tube drainage: 3.8±0.5 days vs 6.5±1.1 days for the standard group (P=.03). No differences in oxygenation were noted between the two groups. The average amount of fluid drained was 1,220 mL. No significant complications were caused by chest tube drainage. Chest tube drainage of transudative pleural effusions resulted in more rapid liberation from mechanical ventilatory support. It is a very safe procedure when performed under ultrasound guidance by experienced personnel. ClinicalTrials.gov; Identifier: NCT0114285; URL: www.clinicaltrials.gov.

Ventilatory inhomogeneity determined from multiple-breath washouts during sustained microgravity on Spacelab SLS-1

NASA Technical Reports Server (NTRS)

Prisk, G. Kim; Guy, Harold J. B.; Elliott, Ann R.; Paiva, Manuel; West, John B.

1995-01-01

We used multiple-breath N2 washouts (MBNW) to study the homogeneity of ventilation in four normal humans (mean age 42.5 yr) before, during, and after 9 days of exposure to microgravity on Spacelab Life Sciences-1. Subjects performed 20-breath MBNW at tidal volumes of approximately 700 ml and 12-breath MBNW at tidal volumes of approximately 1,250 ml. Six indexes of ventilatory inhomogeneity were derived from data from (1) distribution of specific ventilation (SV) from mixed-expired and (2) end-tidal N2, (3) change of slope of N2 washout (semilog plot) with time, (4) change of slope of normalized phase III of successive breaths, (5) anatomic lead dead space, and (6) Bohr dead space. Significant ventilatory inhomogeneity was seen in the standing position at normal gravity (1 G). When we compared standing 1 G with microgravity, the distributions of SV became slightly narrower, but the difference was not significant. Also, there were no significant changes in the change of slope of the N2 washout, change of normalized phase III slopes, or the anatomic and Bohr dead spaces. By contrast, transition from the standing to supine position in 1 G resulted in significantly broader distributions of SV and significantly greater changes in the changes in slope of the N2 washouts, indicating more ventilatory inhomogeneity in that posture. Thus these techniques can detect relatively small changes in ventilatory inhomogeneity. We conclude that the primary determinants of ventilatory inhomogeneity during tidal breathing in the upright posture are not gravitational in origin.

Bronchoscopic lung biopsy using noninvasive ventilatory support: case series and review of literature of NIV-assisted bronchoscopy.

PubMed

Agarwal, Ritesh; Khan, Ajmal; Aggarwal, Ashutosh N; Gupta, Dheeraj

2012-11-01

Fiberoptic bronchoscopy and lung biopsy are important diagnostic tools in patients with diffuse pulmonary infiltrates. However, these patients often have hypoxemic respiratory failure that makes this procedure hazardous. Noninvasive ventilation (NIV) has been shown to improve oxygenation in hypoxemic patients. To report the efficacy and safety of an innovative technique of NIV-assisted bronchoscopic lung biopsy in a small case-series of hypoxemic subjects with diffuse parenchymal infiltrates; also to systematically review the literature on NIV-assisted bronchoscopy. Subjects with bilateral diffuse parenchymal infiltrates and P(aO(2))/F(IO(2)) < 200 mm Hg underwent bronchoscopic lung biopsy under NIV support. NIV was initiated 10 min before the procedure and continued for 30 min after the procedure. The primary outcomes were performance of successful procedure and episodes of decline in S(pO(2)) < 90%. Secondary end points were the change in the respiratory and hemodynamic parameters during the procedure and occurrence of complications such as pneumothorax, hemorrhage, and endotracheal intubation. Six subjects, with a mean ± SD age of 44.5 ± 11.6 years, were included in the study. The median (interquartile range [IQR]) P(aO(2))/F(IO(2)) prior to lung biopsy was 164.5 mm Hg (146.3-176.3 mm Hg), and the median (IQR) inspiratory and expiratory positive airway pressures were 14 cm H(2)O (12-15 cm H(2)O) and 5 cm H(2)O. Fiberoptic bronchoscopy was well tolerated and all subjects maintained S(pO(2)) > 92% during the procedure. One subject required endotracheal intubation due to hemoptysis. A definite diagnosis was obtained in 5 of the 6 subjects. A repeat procedure was performed in one subject, which again yielded no diagnosis. No other periprocedural complications were encountered. NIV-assisted bronchoscopic lung biopsy is a novel method for obtaining diagnosis in hypoxemic patients with diffuse lung infiltrates. However, this approach should be reserved for centers with extensive experience in NIV. More studies are required to define the utility of this approach.

Bayesian inference of the lung alveolar spatial model for the identification of alveolar mechanics associated with acute respiratory distress syndrome

NASA Astrophysics Data System (ADS)

Christley, Scott; Emr, Bryanna; Ghosh, Auyon; Satalin, Josh; Gatto, Louis; Vodovotz, Yoram; Nieman, Gary F.; An, Gary

2013-06-01

Acute respiratory distress syndrome (ARDS) is acute lung failure secondary to severe systemic inflammation, resulting in a derangement of alveolar mechanics (i.e. the dynamic change in alveolar size and shape during tidal ventilation), leading to alveolar instability that can cause further damage to the pulmonary parenchyma. Mechanical ventilation is a mainstay in the treatment of ARDS, but may induce mechano-physical stresses on unstable alveoli, which can paradoxically propagate the cellular and molecular processes exacerbating ARDS pathology. This phenomenon is called ventilator induced lung injury (VILI), and plays a significant role in morbidity and mortality associated with ARDS. In order to identify optimal ventilation strategies to limit VILI and treat ARDS, it is necessary to understand the complex interplay between biological and physical mechanisms of VILI, first at the alveolar level, and then in aggregate at the whole-lung level. Since there is no current consensus about the underlying dynamics of alveolar mechanics, as an initial step we investigate the ventilatory dynamics of an alveolar sac (AS) with the lung alveolar spatial model (LASM), a 3D spatial biomechanical representation of the AS and its interaction with airflow pressure and the surface tension effects of pulmonary surfactant. We use the LASM to identify the mechanical ramifications of alveolar dynamics associated with ARDS. Using graphical processing unit parallel algorithms, we perform Bayesian inference on the model parameters using experimental data from rat lung under control and Tween-induced ARDS conditions. Our results provide two plausible models that recapitulate two fundamental hypotheses about volume change at the alveolar level: (1) increase in alveolar size through isotropic volume change, or (2) minimal change in AS radius with primary expansion of the mouth of the AS, with the implication that the majority of change in lung volume during the respiratory cycle occurs in the alveolar ducts. These two model solutions correspond to significantly different mechanical properties of the tissue, and we discuss the implications of these different properties and the requirements for new experimental data to discriminate between the hypotheses.

The effect of flexible body armour on pulmonary function.

PubMed

Armstrong, Nicola C; Gay, Louise A

2016-05-01

The additional mass and fit of current military in-service body armour (ISBA) can reduce pulmonary function in a way that is characteristic of a restrictive respiratory impairment. This could ultimately impair exercise capacity and military performance. This study compared pulmonary function (forced vital capacity [FVC] and forced expiratory volume in 1 s [FEV1]) in UK ISBA (15.3 kg) and three flexible body armours (BAs) (FA1: 10 kg; FA2: 7.8 kg; FA3: 10 kg) in eight male soldiers. The design of the ballistic plates differed between the BAs to improve the flexibility. FVC and FEV1 were reduced by 4-6%, without reduction in FEV1/FVC for ISBA, FA2 and FA3, when compared to NoBA (p < 0.05). No difference was observed between FA1 and NoBA. As expected, wearing BA caused a mild restrictive ventilatory impairment; however, modifications to BA design can reduce the degree of this impairment. Practitioner Summary: This study showed that wearing body armour caused a mild restrictive ventilatory impairment. However, the design of the armour can be modified to reduce the degree of this impairment. This may lead to improvements in soldier performance during tasks that require body armour.

Increasing the inspiratory time and I:E ratio during mechanical ventilation aggravates ventilator-induced lung injury in mice.

PubMed

Müller-Redetzky, Holger C; Felten, Matthias; Hellwig, Katharina; Wienhold, Sandra-Maria; Naujoks, Jan; Opitz, Bastian; Kershaw, Olivia; Gruber, Achim D; Suttorp, Norbert; Witzenrath, Martin

2015-01-28

Lung-protective ventilation reduced acute respiratory distress syndrome (ARDS) mortality. To minimize ventilator-induced lung injury (VILI), tidal volume is limited, high plateau pressures are avoided, and positive end-expiratory pressure (PEEP) is applied. However, the impact of specific ventilatory patterns on VILI is not well defined. Increasing inspiratory time and thereby the inspiratory/expiratory ratio (I:E ratio) may improve oxygenation, but may also be harmful as the absolute stress and strain over time increase. We thus hypothesized that increasing inspiratory time and I:E ratio aggravates VILI. VILI was induced in mice by high tidal-volume ventilation (HVT 34 ml/kg). Low tidal-volume ventilation (LVT 9 ml/kg) was used in control groups. PEEP was set to 2 cm H2O, FiO2 was 0.5 in all groups. HVT and LVT mice were ventilated with either I:E of 1:2 (LVT 1:2, HVT 1:2) or 1:1 (LVT 1:1, HVT 1:1) for 4 hours or until an alternative end point, defined as mean arterial blood pressure below 40 mm Hg. Dynamic hyperinflation due to the increased I:E ratio was excluded in a separate group of animals. Survival, lung compliance, oxygenation, pulmonary permeability, markers of pulmonary and systemic inflammation (leukocyte differentiation in lung and blood, analyses of pulmonary interleukin-6, interleukin-1β, keratinocyte-derived chemokine, monocyte chemoattractant protein-1), and histopathologic pulmonary changes were analyzed. LVT 1:2 or LVT 1:1 did not result in VILI, and all individuals survived the ventilation period. HVT 1:2 decreased lung compliance, increased pulmonary neutrophils and cytokine expression, and evoked marked histologic signs of lung injury. All animals survived. HVT 1:1 caused further significant worsening of oxygenation, compliance and increased pulmonary proinflammatory cytokine expression, and pulmonary and blood neutrophils. In the HVT 1:1 group, significant mortality during mechanical ventilation was observed. According to the "baby lung" concept, mechanical ventilation-associated stress and strain in overinflated regions of ARDS lungs was simulated by using high tidal-volume ventilation. Increase of inspiratory time and I:E ratio significantly aggravated VILI in mice, suggesting an impact of a "stress/strain × time product" for the pathogenesis of VILI. Thus increasing the inspiratory time and I:E ratio should be critically considered.

Pulmonary compliance and lung volume varies with ecomorphology in anuran amphibians: implications for ventilatory-assisted lymph flux.

PubMed

Hedrick, Michael S; Hillman, Stanley S; Drewes, Robert C; Withers, Philip C

2011-10-01

Vertical movement of lymph from ventral regions to the dorsally located lymph hearts in anurans is accomplished by specialized skeletal muscles working in concert with lung ventilation. We hypothesize that more terrestrial species with greater lymph mobilization capacities and higher lymph flux rates will have larger lung volumes and higher pulmonary compliance than more semi-aquatic or aquatic species. We measured in situ mean and maximal compliance (Δvolume/Δpressure), distensibility (%Δvolume/Δpressure) and lung volume over a range of physiological pressures (1.0 to 4.0 cmH(2)O) for nine species of anurans representing three families (Bufonide, Ranidae and Pipidae) that span a range of body masses and habitats from terrestrial to aquatic. We further examined the relationship between these pulmonary variables and lymph flux for a semi-terrestrial bufonid (Rhinella marina), a semi-aquatic ranid (Lithobates catesbeianus) and an aquatic pipid (Xenopus laevis). Allometric scaling of pulmonary compliance and lung volume with body mass showed significant differences at the family level, with scaling exponents ranging from ∼0.75 in Bufonidae to ∼1.3 in Pipidae. Consistent with our hypothesis, the terrestrial Bufonidae species had significantly greater pulmonary compliance and greater lung volumes compared with semi-aquatic Ranidae and aquatic Pipidae species. Pulmonary distensibility ranged from ∼20 to 35% cmH(2)O(-1) for the three families but did not correlate with ecomorphology. For the three species for which lymph flux data are available, R. marina had a significantly higher (P<0.001) maximal compliance (84.9±2.7 ml cmH(2)O(-1) kg(-1)) and lung volume (242.1±5.5 ml kg(-1)) compared with L. catesbeianus (54.5±0.12 ml cmH(2)O(-1) kg(-1) and 139.3±0.5 ml kg(-1)) and X. laevis (30.8±0.7 ml cmH(2)O(-1) kg(-1) and 61.3±2.5 ml kg(-1)). Lymph flux rates were also highest for R. marina, lowest for X. laevis and intermediate in L. catesbeianus. Thus, there is a strong correlation between pulmonary compliance, lung volume and lymph flux rates, which suggests that lymph mobilization capacity may explain some of the variation in pulmonary compliance and lung volume in anurans.

Adaptation of exercise ventilation during an actively-induced hyperthermia following passive heat acclimation.

PubMed

Beaudin, Andrew E; Clegg, Miriam E; Walsh, Michael L; White, Matthew D

2009-09-01

Hyperthermia-induced hyperventilation has been proposed to be a human thermolytic thermoregulatory response and to contribute to the disproportionate increase in exercise ventilation (VE) relative to metabolic needs during high-intensity exercise. In this study it was hypothesized that VE would adapt similar to human eccrine sweating (E(SW)) following a passive heat acclimation (HA). All participants performed an incremental exercise test on a cycle ergometer from rest to exhaustion before and after a 10-day passive exposure for 2 h/day to either 50 degrees C and 20% relative humidity (RH) (n = 8, Acclimation group) or 24 degrees C and 32% RH (n = 4, Control group). Attainment of HA was confirmed by a significant decrease (P = 0.025) of the esophageal temperature (T(es)) threshold for the onset of E(SW) and a significantly elevated E(SW) (P < or = 0.040) during the post-HA exercise tests. HA also gave a significant decrease in resting T(es) (P = 0.006) and a significant increase in plasma volume (P = 0.005). Ventilatory adaptations during exercise tests following HA included significantly decreased T(es) thresholds (P < or = 0.005) for the onset of increases in the ventilatory equivalents for O(2) (VE/VO(2)) and CO(2) (VE/VCO(2)) and a significantly increased VE (P < or = 0.017) at all levels of T(es). Elevated VE was a function of a significantly greater tidal volume (P = 0.003) at lower T(es) and of breathing frequency (P < or = 0.005) at higher T(es). Following HA, the ventilatory threshold was uninfluenced and the relationships between VO(2) and either VE/VO(2) or VE/VCO(2) did not explain the resulting hyperventilation. In conclusion, the results support that exercise VE following passive HA responds similarly to E(SW), and the mechanism accounting for this adaptation is independent of changes of the ventilatory threshold or relationships between VO(2) with each of VE/VO(2) and VE/VCO(2).

[Demonstration of subclinical pulmonary alveolitis in spondylarthropathies].

PubMed

Jeandel, P; Bonnet, D; Chouc, P Y; Molinier, S; Raphenon, G; Martet, G; Merouze, F; de Muizon, H

1994-05-01

Restrictive ventilatory dysfunction, lowered diffusing capacity, and apical fibrosis have been reported in ankylosing spondylitis. To investigate the pathogenesis of these abnormalities, we studied distal airspace cytology by performing bronchoalveolar lavage in 34 spondyloarthropathy patients (ankylosing spondylitis, n = 16; reactive arthritis, n = 4; axial psoriatic arthritis, n = 2; and undifferentiated spondyloarthropathy with HLA B27-positivity in every case but one, n = 12). Mean age was 32.4 +/- 13.7 years. None of the study patients had apical fibrosis, lower respiratory tract infection, or exposure to airborne pollutants other than tobacco smoke. The control group was composed of nine subjects who had no lung or inflammatory diseases and were not using medications. Significantly higher proportions of lymphocytes were found in bronchoalveolar lavage specimens from patients, as compared with controls. This difference was not influenced by smoking or medication use (non steroidal antiinflammatory drugs, sulfasalazopyridine). Alveolar lymphocytosis was not correlated with laboratory tests for disease activity (erythrocyte sedimentation rate, serum IgA levels) or with the presence of restrictive ventilatory dysfunction. Increases in the proportion of lymphocytes were of similar magnitude in patients with ankylosing spondylitis and in those with other spondyloarthropathies. Absolute total cell counts and relative neutrophil counts were similar in patients and controls. However, among the patients with spondyloarthropathies, those with a disease duration of more than five years had a significantly higher proportion of neutrophils than those with a disease duration of less than five years. These findings demonstrate that spondyloarthropathy patients have subclinical lymphocyte alveolitis. Although of unclear significance, this alveolitis may be related to the development of apical fibrosis in some patients with ankylosing spondylitis.

Chronic Intermittent Hypoxia Blunts the Expression of Ventilatory Long Term Facilitation in Sleeping Rats.

PubMed

Edge, Deirdre; O'Halloran, Ken D

2015-01-01

We have previously reported that chronic intermittent hypoxia (CIH), a central feature of human sleep-disordered breathing, causes respiratory instability in sleeping rats (Edge D, Bradford A, O'halloran KD. Adv Exp Med Biol 758:359-363, 2012). Long term facilitation (LTF) of respiratory motor outputs following exposure to episodic, but not sustained, hypoxia has been described. We hypothesized that CIH would enhance ventilatory LTF during sleep. We examined the effects of 3 and 7 days of CIH exposure on the expression of ventilatory LTF in sleeping rats. Adult male Wistar rats were exposed to 20 cycles of normoxia and hypoxia (5 % O(2) at nadir; SaO(2) ~ 80 %) per hour, 8 h per day for 3 or 7 consecutive days (CIH, N = 7 per group). Corresponding sham groups (N = 7 per group) were subjected to alternating cycles of air under identical experimental conditions in parallel. Following gas exposures, breathing during sleep was assessed in unrestrained, unanaesthetized animals using the technique of whole-body plethysmography. Rats were exposed to room air (baseline) and then to an acute IH (AIH) protocol consisting of alternating periods of normoxia (7 min) and hypoxia (FiO(2) 0.1, 5 min) for 10 cycles. Breathing was monitored during the AIH exposure and for 1 h in normoxia following AIH exposure. Baseline ventilation was elevated after 3 but not 7 days of CIH exposure. The hypoxic ventilatory response was equivalent in sham and CIH animals after 3 days but ventilatory responses to repeated hypoxic challenges were significantly blunted following 7 days of CIH. Minute ventilation was significantly elevated following AIH exposure compared to baseline in sham but not in CIH exposed animals. LTF, determined as the % increase in minute ventilation from baseline following AIH exposure, was significantly blunted in CIH exposed rats. In summary, CIH leads to impaired ventilatory responsiveness to AIH. Moreover, CIH blunts ventilatory LTF. The physiological significance of ventilatory LTF is context-dependent but it is reasonable to consider that it can potentially destabilize respiratory control, in view of the potential for LTF to give rise to hypocapnia. CIH-induced blunting of LTF may represent a compensatory mechanism subserving respiratory homeostasis. Our results suggest that CIH-induced increase in apnoea index (Edge D, Bradford A, O'halloran KD. Adv Exp Med Biol 758:359-363, 2012) is not related to enhanced ventilatory LTF. We conclude that the mature adult respiratory system exhibits plasticity and metaplasticity with potential consequences for the control of respiratory homeostasis. Our results may have implications for human sleep apnoea.

Electrical impedance tomography during major open upper abdominal surgery: a pilot-study

PubMed Central

2014-01-01

Background Electrical impedance tomography (EIT) of the lungs facilitates visualization of ventilation distribution during mechanical ventilation. Its intraoperative use could provide the basis for individual optimization of ventilator settings, especially in patients at risk for ventilation-perfusion mismatch and impaired gas exchange, such as patients undergoing major open upper abdominal surgery. EIT throughout major open upper abdominal surgery could encounter difficulties in belt positioning and signal quality. Thus, we conducted a pilot-study and tested whether EIT is feasible in patients undergoing major open upper abdominal surgery. Methods Following institutional review board’s approval and written informed consent, we included patients scheduled for major open upper abdominal surgery of at least 3 hours duration. EIT measurements were conducted prior to intubation, at the time of skin incision, then hourly during surgery until shortly prior to extubation and after extubation. Number of successful intraoperative EIT measurements and reasons for failures were documented. From the valid measurements, a functional EIT image of changes in tidal impedance was generated for every time point. Regions of interest were defined as horizontal halves of the picture. Monitoring of ventilation distribution was assessed using the center of ventilation index, and also using the total and dorsal ventilated lung area. All parameter values prior to and post intubation as well as extubation were compared. A p < 0.05 was considered statistically significant. Results A total of 120 intraoperative EIT measurements during major abdominal surgery lasting 4-13 hours were planned in 14 patients. The electrode belt was attached between the 2nd and 4th intercostal space. Consecutive valid measurements could be acquired in 13 patients (93%). 111 intraoperative measurements could be retrieved as planned (93%). Main obstacle was the contact of skin electrodes. Despite the high belt position, distribution of tidal volume showed a significant shift of ventilation towards ventral lung regions after intubation. This was reversed after weaning from mechanical ventilation. Conclusions Despite a high belt position, monitoring of ventilation distribution is feasible in patients undergoing major open upper abdominal surgery lasting from 4 to 13 hours. Therefore, further interventional trials in order to optimize ventilatory management should be initiated. PMID:25018668

Impact of beta-blockers on cardiopulmonary exercise testing in patients with advanced liver disease.

PubMed

Wallen, M P; Hall, A; Dias, K A; Ramos, J S; Keating, S E; Woodward, A J; Skinner, T L; Macdonald, G A; Arena, R; Coombes, J S

2017-10-01

Patients with advanced liver disease may develop portal hypertension that can result in variceal haemorrhage. Beta-blockers reduce portal pressure and minimise haemorrhage risk. These medications may attenuate measures of cardiopulmonary performance, such as the ventilatory threshold and peak oxygen uptake measured via cardiopulmonary exercise testing. To determine the effect of beta-blockers on cardiopulmonary exercise testing variables in patients with advanced liver disease. This was a cross-sectional analysis of 72 participants who completed a cardiopulmonary exercise test before liver transplantation. All participants remained on their usual beta-blocker dose and timing prior to the test. Variables measured during cardiopulmonary exercise testing included the ventilatory threshold, peak oxygen uptake, heart rate, oxygen pulse, the oxygen uptake efficiency slope and the ventilatory equivalents for carbon dioxide slope. Participants taking beta-blockers (n = 28) had a lower ventilatory threshold (P <.01) and peak oxygen uptake (P = .02), compared to participants not taking beta-blockers. After adjusting for age, the model of end-stage liver-disease score, liver-disease aetiology, presence of refractory ascites and ventilatory threshold remained significantly lower in the beta-blocker group (P = .04). The oxygen uptake efficiency slope was not impacted by beta-blocker use. Ventilatory threshold is reduced in patients with advanced liver disease taking beta-blockers compared to those not taking the medication. This may incorrectly risk stratify patients on beta-blockers and has implications for patient management before and after liver transplantation. The oxygen uptake efficiency slope was not influenced by beta-blockers and may therefore be a better measure of cardiopulmonary performance in this patient population. © 2017 John Wiley & Sons Ltd.

Increased ventilatory variability and complexity in patients with hyperventilation disorder.

PubMed

Bokov, Plamen; Fiamma, Marie-Noëlle; Chevalier-Bidaud, Brigitte; Chenivesse, Cécile; Straus, Christian; Similowski, Thomas; Delclaux, Christophe

2016-05-15

It has been hypothesized that hyperventilation disorders could be characterized by an abnormal ventilatory control leading to enhanced variability of resting ventilation. The variability of tidal volume (VT) often depicts a nonnormal distribution that can be described by the negative slope characterizing augmented breaths formed by the relationship between the probability density distribution of VT and VT on a log-log scale. The objectives of this study were to describe the variability of resting ventilation [coefficient of variation (CV) of VT and slope], the stability in respiratory control (loop, controller and plant gains characterizing ventilatory-chemoresponsiveness interactions) and the chaotic-like dynamics (embedding dimension, Kappa values characterizing complexity) of resting ventilation in patients with a well-defined dysfunctional breathing pattern characterized by air hunger and constantly decreased PaCO2 during a cardiopulmonary exercise test. Compared with 14 healthy subjects with similar anthropometrics, 23 patients with hyperventilation were characterized by increased variability of resting tidal ventilation (CV of VT median [interquartile]: 26% [19-35] vs. 36% [28-48], P = 0.020; slope: -6.63 [-7.65; -5.36] vs. -3.88 [-5.91; -2.66], P = 0.004) that was not related to increased chemical drive (loop gain: 0.051 [0.039-0.221] vs. 0.044 [0.012-0.087], P = 0.149) but that was related to an increased ventilatory complexity (Kappa values, P < 0.05). Plant gain was decreased in patients and correlated with complexity (with Kappa 5 - degree 5: Rho = -0.48, P = 0.006). In conclusion, well-defined patients suffering from hyperventilation disorder are characterized by increased variability of their resting ventilation due to increased ventilatory complexity with stable ventilatory-chemoresponsiveness interactions. Copyright © 2016 the American Physiological Society.

Gender considerations in ventilatory and metabolic development in rats: special emphasis on the critical period

PubMed Central

LIU, QIULI; WONG-RILEY, MARGARET T.T

2013-01-01

In rats, a critical period exists around postnatal day (P) 12-13, when an imbalance between heightened inhibition and suppressed excitation led to a weakened ventilatory and metabolic response to acute hypoxia. An open question was whether the two genders follow the same or different developmental trends throughout the first 3 postnatal weeks and whether the critical period exists in one or both genders. The present large-scale, in-depth ventilatory and metabolic study was undertaken to address this question. Our data indicated that: 1) the ventilatory and metabolic rates in both normoxia and acute hypoxia were comparable between the two genders from P0 to P21; thus, gender was never significant as a main effect; and 2) the age effect was highly significant in all parameters studies for both genders, and both genders exhibited a significantly weakened response to acute hypoxia during the critical period. Thus, the two genders have comparable developmental trends, and the critical period exists in both genders in rats. PMID:23797186

Alteration by hyperoxia of ventilatory dynamics during sinusoidal work.

PubMed

Casaburi, R; Stremel, R W; Whipp, B J; Beaver, W L; Wasserman, K

1980-06-01

The effects of hyperoxia on ventilatory and gas exchange dynamics were studied utilizing sinusoidal work rate forcings. Five subjects exercised on 14 occasions on a cycle ergometer for 30 min with a sinusoidally varying work load. Tests were performed at seven frequencies of work load during air or 100% O2 inspiration. From the breath-by-breath responses to these tests, dynamic characteristics were analyzed by extracting the mean level, amplitude of oscillation, and phase lag for each six variables with digital computer techniques. Calculation of the time constant (tau) of the ventilatory responses demonstrated that ventilatory kinetics were slower during hyperoxia than during normoxia (P less than 0.025; avg 1.56 and 1.13 min, respectively). Further, for identical work rate fluctuations, end-tidal CO2 tension fluctuations were increased by hyperpoxia. Ventilation during hyperoxia is slower to respond to variations in the level of metabolically produced CO2, presumably because hyperoxia attenuates carotid body output; the arterial CO2 tension is consequently less tightly regulated.

Effect of treatment with nasal continuous positive airway pressure on ventilatory response to hypoxia and hypercapnia in patients with sleep apnea syndrome.

PubMed

Spicuzza, Lucia; Bernardi, Luciano; Balsamo, Rossella; Ciancio, Nicola; Polosa, Riccardo; Di Maria, Giuseppe

2006-09-01

The increase in peripheral chemoreflex sensitivity in patients with obstructive sleep apnea (OSA) is associated with activation of autonomic nervous system and hemodynamic responses. Nasal CPAP (nCPAP) is an effective treatment for OSA, but little is known on its effect on chemoreflex sensitivity. To assess the effect of nCPAP treatment or placebo (sham nCPAP) on ventilatory control in patients with OSA. Sleep laboratory of Azienda Ospedaliera Garibaldi. Twenty-five patients with moderate-to-severe OSA. Patients were randomly assigned to either therapeutic nCPAP (use of optimal pressure, n = 15) or sham nCPAP (suboptimal pressure of 1 to 2 cm H2O, n = 10) in a double-blind fashion and treated for 1 month. A rebreathing test to assess ventilatory response to normocapnic hypoxia and normoxic hypercapnia was performed at basal condition and after 1 month of treatment. The use of therapeutic nCPAP or sham nCPAP did not affect daytime percentage of arterial oxygen saturation (SaO2%) or end-tidal P(CO2). The normocapnic hypoxic ventilatory response was reduced after 1 month of treatment with nCPAP (the slope was 1.08 +/- 0.02 L/min/SaO2% at basal condition and 0.53 +/- 0.07 L/min/SaO2% after 1 month of treatment, p = 0.008) [mean +/- SD], but not in patients treated with sham nCPAP (slope, 0.83 +/- 0.09 L/min/SaO2% and 0.85 +/- 0.19 L/min/SaO2% at basal condition and after 1 month, respectively). The normoxic hypercapnic ventilatory response remained unchanged after 1 month in both groups. No changes in ventilatory response to either hypoxia or hypercapnia were observed after a single night of nCPAP treatment. The ventilatory response to hypoxia is reduced during regular treatment, but not after short-term treatment, with nCPAP. Readjusted peripheral oxygen chemosensitivity during nCPAP treatment may be a side effect of both reduced sympathetic activity and increased baroreflex activity, or a possible continuous positive airway pressure-related mechanism leading to a reduced activation of autonomic nervous system per se.

Intermittent hypercapnic hypoxia during sleep does not induce ventilatory long-term facilitation in healthy males.

PubMed

Deacon, Naomi L; McEvoy, R Doug; Stadler, Daniel L; Catcheside, Peter G

2017-09-01

Intermittent hypoxia-induced ventilatory neuroplasticity is likely important in obstructive sleep apnea pathophysiology. Although concomitant CO 2 levels and arousal state critically influence neuroplastic effects of intermittent hypoxia, no studies have investigated intermittent hypercapnic hypoxia effects during sleep in humans. Thus the purpose of this study was to investigate if intermittent hypercapnic hypoxia during sleep induces neuroplasticity (ventilatory long-term facilitation and increased chemoreflex responsiveness) in humans. Twelve healthy males were exposed to intermittent hypercapnic hypoxia (24 × 30 s episodes of 3% CO 2 and 3.0 ± 0.2% O 2 ) and intermittent medical air during sleep after 2 wk washout period in a randomized crossover study design. Minute ventilation, end-tidal CO 2 , O 2 saturation, breath timing, upper airway resistance, and genioglossal and diaphragm electromyograms were examined during 10 min of stable stage 2 sleep preceding gas exposure, during gas and intervening room air periods, and throughout 1 h of room air recovery. There were no significant differences between conditions across time to indicate long-term facilitation of ventilation, genioglossal or diaphragm electromyogram activity, and no change in ventilatory response from the first to last gas exposure to suggest any change in chemoreflex responsiveness. These findings contrast with previous intermittent hypoxia studies without intermittent hypercapnia and suggest that the more relevant gas disturbance stimulus of concomitant intermittent hypercapnia frequently occurring in sleep apnea influences acute neuroplastic effects of intermittent hypoxia. These findings highlight the need for further studies of intermittent hypercapnic hypoxia during sleep to clarify the role of ventilatory neuroplasticity in the pathophysiology of sleep apnea. NEW & NOTEWORTHY Both arousal state and concomitant CO 2 levels are known modulators of the effects of intermittent hypoxia on ventilatory neuroplasticity. This is the first study to investigate the effects of combined intermittent hypercapnic hypoxia during sleep in humans. The lack of neuroplastic effects suggests a need for further studies more closely replicating obstructive sleep apnea to determine the pathophysiological relevance of intermittent hypoxia-induced ventilatory neuroplasticity. Copyright © 2017 the American Physiological Society.

Evidence for Avian Intrathoracic Air Sacs in a New Predatory Dinosaur from Argentina

PubMed Central

Sereno, Paul C.; Martinez, Ricardo N.; Wilson, Jeffrey A.; Varricchio, David J.; Alcober, Oscar A.; Larsson, Hans C. E.

2008-01-01

Background Living birds possess a unique heterogeneous pulmonary system composed of a rigid, dorsally-anchored lung and several compliant air sacs that operate as bellows, driving inspired air through the lung. Evidence from the fossil record for the origin and evolution of this system is extremely limited, because lungs do not fossilize and because the bellow-like air sacs in living birds only rarely penetrate (pneumatize) skeletal bone and thus leave a record of their presence. Methodology/Principal Findings We describe a new predatory dinosaur from Upper Cretaceous rocks in Argentina, Aerosteon riocoloradensis gen. et sp. nov., that exhibits extreme pneumatization of skeletal bone, including pneumatic hollowing of the furcula and ilium. In living birds, these two bones are pneumatized by diverticulae of air sacs (clavicular, abdominal) that are involved in pulmonary ventilation. We also describe several pneumatized gastralia (“stomach ribs”), which suggest that diverticulae of the air sac system were present in surface tissues of the thorax. Conclusions/Significance We present a four-phase model for the evolution of avian air sacs and costosternal-driven lung ventilation based on the known fossil record of theropod dinosaurs and osteological correlates in extant birds: (1) Phase I—Elaboration of paraxial cervical air sacs in basal theropods no later than the earliest Late Triassic. (2) Phase II—Differentiation of avian ventilatory air sacs, including both cranial (clavicular air sac) and caudal (abdominal air sac) divisions, in basal tetanurans during the Jurassic. A heterogeneous respiratory tract with compliant air sacs, in turn, suggests the presence of rigid, dorsally attached lungs with flow-through ventilation. (3) Phase III—Evolution of a primitive costosternal pump in maniraptoriform theropods before the close of the Jurassic. (4) Phase IV—Evolution of an advanced costosternal pump in maniraptoran theropods before the close of the Jurassic. In addition, we conclude: (5) The advent of avian unidirectional lung ventilation is not possible to pinpoint, as osteological correlates have yet to be identified for uni- or bidirectional lung ventilation. (6) The origin and evolution of avian air sacs may have been driven by one or more of the following three factors: flow-through lung ventilation, locomotory balance, and/or thermal regulation. PMID:18825273

Peripheral chemoreceptor activity in sleeping neonates exposed to warm environments.

PubMed

Chardon, K; Bach, V; Telliez, F; Tourneux, P; Elabbassi, E B; Cardot, V; Gaultier, C; Libert, J P

2003-09-01

In neonates, it is often assumed that ventilatory control and heat stress interact. Thus the two factors have been implicated in various pathologies (apnoea, sudden infant death syndrome). However, little is known about the mechanisms of this interaction, and the influence of sleep is still debated. This study aimed at determining the influence of warm exposure on the decrease in ventilation during a hyperoxic test (HT), which is considered to be a measure of peripheral chemoreceptor activity. The test was performed in active (AS) and quiet sleep (QS) in 12 neonates exposed to thermoneutral or warm environments. The HT consisted of 30 s of inspired, 100% O(2). The ventilatory response was assessed in terms of a response time, defined as the time elapsing between HT onset and the first significant change in V(E). Our results show that, in both thermal conditions, the fall in V(E) was higher in AS than in QS. Warm exposure significantly enhanced the ventilatory response in AS (-27.5 +/- 8.7% vs. -38.3 +/- 8.8%, P < 0.01) but not in QS. A thermometabolic drive or inputs from thermoreceptors could be involved in the reinforcement of peripheral chemoreceptor activity in AS in warmer environments, which could contribute to an increasing risk of apnoea in neonates with altered chemoreceptor function. Since hypothalamic structures are involved in thermoregulatory, sleep processes and (probably) in respiratory control, it could well be the principal site where this interaction occurs.

[Neurally adjusted ventilatory assist (NAVA). A new mode of assisted mechanical ventilation].

PubMed

Moerer, O; Barwing, J; Quintel, M

2008-10-01

The aim of mechanical ventilation is to assure gas exchange while efficiently unloading the respiratory muscles and mechanical ventilation is an integral part of the care of patients with acute respiratory failure. Modern lung protective strategies of mechanical ventilation include low-tidal-volume ventilation and the continuation of spontaneous breathing which has been shown to be beneficial in reducing atelectasis and improving oxygenation. Poor patient-ventilator interaction is a major issue during conventional assisted ventilation. Neurally adjusted ventilator assist (NAVA) is a new mode of mechanical ventilation that uses the electrical activity of the diaphragm (EAdi) to control the ventilator. First experimental studies showed an improved patient-ventilator synchrony and an efficient unloading of the respiratory muscles. Future clinical studies will have to show that NAVA is of clinical advantage when compared to conventional modes of assisted mechanical ventilation. This review characterizes NAVA according to current publications on this topic.

Scurvy in an alcoholic patient treated with intravenous vitamins

PubMed Central

Ong, John; Randhawa, Rabinder

2014-01-01

Vitamin C deficiency is rare in developed countries but there is an increased prevalence in chronic alcohol abusers. In the UK, it is common practice to treat patients with chronic alcoholism who are admitted to hospital with intravenous vitamins B1, B2, B3, B6 and C for 2–3 days, followed by oral thiamine and vitamin B-compound tablets. This is a case of a 57-year-old man with a history of chronic alcoholism and chronic obstructive lung disease who was admitted to the intensive care unit for pneumonia requiring ventilatory support. He was given high doses of intravenous vitamins B1, B2, B3, B6 and C for 3 days then oral thiamine and vitamin B compound tablets but developed scurvy 4 days later. He was restarted on oral vitamin C supplementation and showed signs of improvement within 3 days of treatment. PMID:24728889

Real-Time Cameraless Measurement System Based on Bioelectrical Ventilatory Signals to Evaluate Fear and Anxiety.

PubMed

Soh, Zu; Matsuno, Motoki; Yoshida, Masayuki; Tsuji, Toshio

2018-04-01

Fear and anxiety in fish are generally evaluated by video-based behavioral analysis. However, it is difficult to distinguish the psychological state of fish exclusively through video analysis, particularly whether the fish are freezing, which represents typical fear behavior, or merely resting. We propose a system that can measure bioelectrical signals called ventilatory signals and simultaneously analyze swimming behavior in real time. Experimental results comparing the behavioral analysis of the proposed system and the camera system showed a low error level with an average absolute position error of 9.75 ± 3.12 mm (about one-third of the body length) and a correlation between swimming speeds of r = 0.93 ± 0.07 (p < 0.01). We also exposed the fish to zebrafish skin extracts containing alarm substances that induce fear and anxiety responses to evaluate their emotional changes. The results confirmed that this solution significantly changed all behavioral and ventilatory signal indices obtained by the proposed system (p < 0.01). By combining the behavioral and ventilatory signal indices, we could detect fear and anxiety with a discrimination rate of 83.3% ± 16.7%. Furthermore, we found that the decreasing fear and anxiety over time could be detected according to the peak frequency of the ventilatory signals, which cannot be measured through video analysis.

Effect of menstrual cycle phase on the ventilatory response to rising body temperature during exercise.

PubMed

Hayashi, Keiji; Kawashima, Takayo; Suzuki, Yuichi

2012-07-01

To examine the effect of menstrual cycle on the ventilatory sensitivity to rising body temperature, ten healthy women exercised for ~60 min on a cycle ergometer at 50% of peak oxygen uptake during the follicular and luteal phases of their cycle. Esophageal temperature, mean skin temperature, mean body temperature, minute ventilation, and tidal volume were all significantly higher at baseline and during exercise in the luteal phase than the follicular phase. On the other hand, end-tidal partial pressure of carbon dioxide was significantly lower during exercise in the luteal phase than the follicular phase. Plotting ventilatory parameters against esophageal temperature revealed there to be no significant menstrual cycle-related differences in the slopes or intercepts of the regression lines, although minute ventilation and tidal volume did significantly differ during exercise with mild hyperthermia. To evaluate the cutaneous vasodilatory response, relative laser-Doppler flowmetry values were plotted against mean body temperature, which revealed that the mean body temperature threshold for cutaneous vasodilation was significantly higher in the luteal phase than the follicular phase, but there were no significant differences in the sensitivity or peak values. These results suggest that the menstrual cycle phase influences the cutaneous vasodilatory response during exercise and the ventilatory response at rest and during exercise with mild hyperthermia, but it does not influence ventilatory responses during exercise with moderate hyperthermia.

Benefits of Manometer in Non-Invasive Ventilatory Support.

PubMed

Lacerda, Rodrigo Silva; de Lima, Fernando Cesar Anastácio; Bastos, Leonardo Pereira; Fardin Vinco, Anderson; Schneider, Felipe Britto Azevedo; Luduvico Coelho, Yves; Fernandes, Heitor Gomes Costa; Bacalhau, João Marcus Ramos; Bermudes, Igor Matheus Simonelli; da Silva, Claudinei Ferreira; da Silva, Luiza Paterlini; Pezato, Rogério

2017-12-01

Introduction Effective ventilation during cardiopulmonary resuscitation (CPR) is essential to reduce morbidity and mortality rates in cardiac arrest. Hyperventilation during CPR reduces the efficiency of compressions and coronary perfusion. Problem How could ventilation in CPR be optimized? The objective of this study was to evaluate non-invasive ventilator support using different devices. The study compares the regularity and intensity of non-invasive ventilation during simulated, conventional CPR and ventilatory support using three distinct ventilation devices: a standard manual resuscitator, with and without airway pressure manometer, and an automatic transport ventilator. Student's t-test was used to evaluate statistical differences between groups. P values <.05 were regarded as significant. Peak inspiratory pressure during ventilatory support and CPR was significantly increased in the group with manual resuscitator without manometer when compared with the manual resuscitator with manometer support (MS) group or automatic ventilator (AV) group. The study recommends for ventilatory support the use of a manual resuscitator equipped with MS or AVs, due to the risk of reduction in coronary perfusion pressure and iatrogenic thoracic injury during hyperventilation found using manual resuscitator without manometer. Lacerda RS , de Lima FCA , Bastos LP , Vinco AF , Schneider FBA , Coelho YL , Fernandes HGC , Bacalhau JMR , Bermudes IMS , da Silva CF , da Silva LP , Pezato R . Benefits of manometer in non-invasive ventilatory support. Prehosp Disaster Med. 2017;32(6):615-620.

Ventilatory Responsiveness of Goats with Ablated Carotid Bodies,

DTIC Science & Technology

1982-06-03

R.A.Gabel, D.E. Leith, and V. Fencl 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK AREA & WORK UNIT NUMBERS US Army... vestigial ventilatory response to cyanide. These findings persisted throughout 10 the 5 months of our observation, in contrast with the observations of

Quantitative chest computed tomography as a means of predicting exercise performance in severe emphysema.

PubMed

Crausman, R S; Ferguson, G; Irvin, C G; Make, B; Newell, J D

1995-06-01

We assessed the value of quantitative high-resolution computed tomography (CT) as a diagnostic and prognostic tool in smoking-related emphysema. We performed an inception cohort study of 14 patients referred with emphysema. The diagnosis of emphysema was based on a compatible history, physical examination, chest radiograph, CT scan of the lung, and pulmonary physiologic evaluation. As a group, those who underwent exercise testing were hyperinflated (percentage predicted total lung capacity +/- standard error of the mean = 133 +/- 9%), and there was evidence of air trapping (percentage predicted respiratory volume = 318 +/- 31%) and airflow limitation (forced expiratory volume in 1 sec [FEV1] = 40 +/- 7%). The exercise performance of the group was severely limited (maximum achievable workload = 43 +/- 6%) and was characterized by prominent ventilatory, gas exchange, and pulmonary vascular abnormalities. The quantitative CT index was markedly elevated in all patients (76 +/- 9; n = 14; normal < 4). There were correlations between this quantitative CT index and measures of airflow limitation (FEV1 r2 = .34, p = 09; FEV1/forced vital capacity r2 = .46, p = .04) and between maximum workload achieved (r2 = .93, p = .0001) and maximum oxygen utilization (r2 = .83, p = .0007). Quantitative chest CT assessment of disease severity is correlated with the degree of airflow limitation and exercise impairment in pulmonary emphysema.

Respiratory physiology and pathological anxiety.

PubMed

Gorman, J M; Uy, J

1987-11-01

There has been comparatively little attention paid to the respiratory derangements in anxiety disorders. Some authorities contend, however, that indices of respiratory function may be the best objective marker of anxiety state. Furthermore, an understanding of the ventilatory status of patients with anxiety disorder has shed light on the basic pathophysiology of abnormal anxiety. For example, it is now clear that patients with a wide variety of anxiety disorders hyperventilate both chronically and acutely. Therefore, we present an explanation of the physiological changes produced by hyperventilation. In order to further study ventilatory physiology in patients with anxiety disorder, our group and others have used the carbon dioxide challenge test. The data from these experiments suggest that patients with panic disorder are hypersensitive to carbon dioxide and that carbon dioxide inhalation induces panic attacks in susceptible patients. Hyperventilation appears to be a secondary, but pathophysiologically important, event in the generation of acute panic. The implications of work in respiratory physiology for clinical management of patients with anxiety disorder are discussed.

[Non-invasive mechanical ventilation in the pre- and intraoperative period and difficult airway].

PubMed

Esquinas, A M; Jover, J L; Úbeda, A; Belda, F J

2015-11-01

Non-invasive mechanical ventilation is a method of ventilatory assistance aimed at increasing alveolar ventilation, thus achieving, in selected subjects, the avoidance of endotracheal intubation and invasive mechanical ventilation, with the consequent improvement in survival. There has been a systematic review and study of the technical, clinical experiences, and recommendations concerning the application of non-invasive mechanical ventilation in the pre- and intraoperative period. The use of prophylactic non-invasive mechanical ventilation before surgery that involves significant alterations in the ventilatory function may decrease the incidence of postoperative respiratory complications. Its intraoperative use will mainly depend on the type of surgery, type of anaesthetic technique, and the clinical status of the patient. Its use allows greater anaesthetic depth without deterioration of oxygenation and ventilation of patients. Copyright © 2015 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

Clinical review: Humidifiers during non-invasive ventilation - key topics and practical implications

PubMed Central

2012-01-01

Inadequate gas conditioning during non-invasive ventilation (NIV) can impair the anatomy and function of nasal mucosa. The resulting symptoms may have a negative effect on patients' adherence to ventilatory treatment, especially for chronic use. Several parameters, mostly technical aspects of NIV, contribute to inefficient gas conditioning. Factors affecting airway humidity during NIV include inspiratory flow, inspiratory oxygen fraction, leaks, type of ventilator, interface used to deliver NIV, temperature and pressure of inhaled gas, and type of humidifier. The correct application of a humidification system may avoid the effects of NIV-induced drying of the airway. This brief review analyses the consequences of airway dryness in patients receiving NIV and the technical tools necessary to guarantee adequate gas conditioning during ventilatory treatment. Open questions remain about the timing of gas conditioning for acute or chronic settings, the choice and type of humidification device, the interaction between the humidifier and the underlying disease, and the effects of individual humidification systems on delivered humidity. PMID:22316078

Physiological Effects of Positive Pressure Ventilation.

DTIC Science & Technology

1992-05-01

function in the patient with respiratory failure . In R. R. Kirby, M. J. Banner, & J. B. Downs (Eds.), Clinical Applications of Ventilatory Su2Rort (pp. 301...G., Blehschmidt, N. G., & Linder, W. J. (1990). Positive-pressure ventilation with positive end-expiratory pressure and atrial natriuretic peptide ...Acute Resniratorv Failure . New York: Churchill Livingstone. Ventilation 1 Physiological Effects of Positive Pressure Ventilation Dennis L. Oakes, RN, BSN

Effect of enteral feeding with eicosapentaenoic acid, gamma-linolenic acid, and antioxidants in patients with acute respiratory distress syndrome. Enteral Nutrition in ARDS Study Group.

PubMed

Gadek, J E; DeMichele, S J; Karlstad, M D; Pacht, E R; Donahoe, M; Albertson, T E; Van Hoozen, C; Wennberg, A K; Nelson, J L; Noursalehi, M

1999-08-01

Recent studies in animal models of sepsis-induced acute respiratory distress syndrome (ARDS) have shown that a low-carbohydrate, high-fat diet combining the anti-inflammatory and vasodilatory properties of eicosapentaenoic acid (EPA; fish oil), gamma-linolenic acid (GLA; borage oil) (EPA+GLA), and antioxidants improves lung microvascular permeability, oxygenation, and cardiopulmonary function and reduces proinflammatory eicosanoid synthesis and lung inflammation. These findings suggest that enteral nutrition with EPA+GLA and antioxidants may reduce pulmonary inflammation and may improve oxygenation and clinical outcomes in patients with ARDS. Prospective, multicentered, double-blind, randomized controlled trial. Intensive care units of five academic and teaching hospitals in the United States. We enrolled 146 patients with ARDS (as defined by the American-European Consensus Conference) caused by sepsis/pneumonia, trauma, or aspiration injury in the study. Patients meeting entry criteria were randomized and continuously tube-fed either EPA+GLA or an isonitrogenous, isocaloric standard diet at a minimum caloric delivery of 75% of basal energy expenditure x 1.3 for at least 4-7 days. Arterial blood gases were measured, and ventilator settings were recorded at baseline and study days 4 and 7 to enable calculation of PaO2/FIO2, a measure of gas exchange. Pulmonary neutrophil recruitment was assessed by measuring the number of neutrophils and the total cell count in bronchoalveolar lavage fluid at the same time points. Clinical outcomes were recorded. Baseline characteristics of 98 evaluable patients revealed that key demographic, physiologic, and ventilatory variables were similar at entry between both groups. Multiple bronchoalveolar lavages revealed significant decreases (approximately 2.5-fold) in the number of total cells and neutrophils per mL of recovered lavage fluid during the study with EPA+GLA compared with patients fed the control diet. Significant improvements in oxygenation (PaO2/FIO2) from baseline to study days 4 and 7 with lower ventilation variables (FIO2, positive end-expiratory pressure, and minute ventilation) occurred in patients fed EPA+GLA compared with controls. Patients fed EPA+GLA required significantly fewer days of ventilatory support (11 vs. 16.3 days; p = .011), and had a decreased length of stay in the intensive care unit (12.8 vs. 17.5 days; p = .016) compared with controls. Only four of 51 (8%) patients fed EPA+GLA vs. 13 of 47 (28%) control patients developed a new organ failure during the study (p = .015). The beneficial effects of the EPA+GLA diet on pulmonary neutrophil recruitment, gas exchange, requirement for mechanical ventilation, length of intensive care unit stay, and the reduction of new organ failures suggest that this enteral nutrition formula would be a useful adjuvant therapy in the clinical management of patients with or at risk of developing ARDS.

Fixed-distance walk tests at comfortable and fast speed: Potential tools for the functional assessment of coronary patients?

PubMed

Morard, Marie-Doriane; Besson, Delphine; Laroche, Davy; Naaïm, Alexandre; Gremeaux, Vincent; Casillas, Jean-Marie

2017-01-01

There is ambiguity concerning the walk tests available for functional assessment of coronary patients, particularly for the walking speed. This study explores the psychometric properties of two walking tests, based on fixed-distance tests, at comfortable and fast velocity, in stabilized patients at the end of a cardiac rehabilitation program. At a three-day interval 58 coronary patients (mean age of 64.85±6.03 years, 50 men) performed three walk tests, the first two at a comfortable speed in a random order (6-minute walk test - 6MWT - and 400-metre comfortable walk test - 400mCWT) and the third at a brisk speed (200-metre fast walk test - 200mFWT). A modified Bruce treadmill test was associated at the end of the second phase. Monitored main parameters were: heart rate, walking velocity, VO 2 . Tolerance to the 3 tests was satisfactory. The reliability of the main parameters was good (intraclass correlation coefficient>0.8). The VO 2 concerning 6MWT and 400mCWT were not significantly different (P=0.33) and were lower to the first ventilatory threshold determined by the stress test (P<0.001): 16.2±3.0 vs. 16.5±2.6 vs. 20.7±5.1mL·min -1 ·kg -1 respectively. The VO 2 of the 200mFWT (20.2±3.7) was not different from the first ventilatory threshold. 400mCWT and 200mFWT are feasible, well-tolerated and reliable. They explore two levels of effort intensity (lower and not different to the first ventilatory threshold respectively). 400mCWT is a possible alternative to 6MWT. Associated with 200mFWT it should allow a better measurement of physical capacities and better customization of exercise training. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Anesthesia and ventilation strategies in children with asthma: part II - intraoperative management.

PubMed

Regli, Adrian; von Ungern-Sternberg, Britta S

2014-06-01

As asthma is a frequent disease especially in children, anesthetists are increasingly providing anesthesia for children requiring elective surgery with well controlled asthma but also for those requiring urgent surgery with poorly controlled or undiagnosed asthma. This second part of this two-part review details the medical and ventilatory management throughout the perioperative period in general but also includes the perioperative management of acute bronchospasm and asthma exacerbations in children with asthma. Multiple observational trials assessing perioperative respiratory adverse events in healthy and asthmatic children provide the basis for identifying risk reduction strategies. Mainly, animal experiments and to a small extent clinical data have advanced our understanding of how anesthetic agents effect bronchial smooth muscle tone and blunt reflex bronchoconstriction. Asthma treatment outside anesthesia is well founded on a large body of evidence.Perioperative prevention strategies have increasingly been studied. However, evidence on the perioperative management, including mechanical ventilation strategies of asthmatic children, is still only fair, and further research is required. To minimize the considerable risk of perioperative respiratory adverse events in asthmatic children, perioperative management should be based on two main pillars: the preoperative optimization of asthma treatment (please refer to the first part of this two-part review) and - the focus of this second part of this review - the optimization of anesthesia management in order to optimize lung function and minimize bronchial hyperreactivity in the perioperative period.

Lung Function Changes in Mice Sensitized to Ammonium ...

EPA Pesticide Factsheets

Occupational exposure to halogenated platinum salts can trigger the development of asthma. The risk to the general population that may result from the use of platinum in catalytic converters and its emerging use as a diesel fuel additive is unclear. To investigate pulmonary responses to platinum, we developed a mouse model of platinum hypersensitivity. Mice were sensitized through application of ammonium hexachloroplatinate (AHCP) to the shaved back on days 0, 5 and 19, and to each ear on days 10, 11 and 12. On days 24 and 29, mice were challenged by oropharyngeal aspiration with AHCP in saline. Before and immediately after challenge, pulmonary responses were assessed using whole body plethysmography (WBP). A dose-dependentincrease in immediate responses was observed in AHCP-sensitized and challenged mice. On days 26 and 31, changes in ventilatory responses to methacholine (Mch) aerosol were assessed by WBP; dose-dependent increases in Mch responsiveness occurred in sensitized mice. Lymph node cell counts indicate a proliferative response in lymph nodes drainng the sites of application. Bronchoalveolar lavage fluid harvested from sensitized mice contained an average of 5% eosinophils compared to less than 0.5% in non-sensitized mice (p < 0.05); significant increases in total serum immunoglobulin E were observed for all sensitized mice. Although a second airway challenge on day 29 affected some results, only one airway challenge was needed to observe changes in l

Positive-pressure ventilation during transport: a randomized crossover study of self-inflating and flow-inflating resuscitators in a simulation model.

PubMed

Lucy, Malcolm J; Gamble, Jonathan J; Daku, Brian L; Bryce, Rhonda D; Rana, Masud

2014-12-01

Positive-pressure ventilation during transport of intubated patients is generally delivered via a hand-pressurized device. Of these devices, self-inflating resuscitators (SIR) and flow-inflating resuscitators (FIR) constitute the two major types used. Selection of a particular device for transport, however, remains largely an institutional practice. To evaluate the hypothesis that transport ventilation goals of intubated pediatric patients are better achieved using an FIR compared to an SIR. This randomized crossover simulation study compared the performance of SIR and FIR among anesthesia providers in a pediatric transport scenario. Subjects hand-ventilated a test lung while simultaneously maneuvering a stretcher bed to simulate patient transport. Hand ventilation was carried out using a Jackson-Rees circuit (FIR) and a Laerdal pediatric silicone resuscitator (SIR). The primary outcome was the proportion of total breaths delivered within the predefined target PIP/PEEP range (30+/- 3, 10+/- 3 cm H2O). Secondary outcomes included proportion of total breaths delivered with operationally defined unacceptable breath variables (PIP > 35 cm H2O or PEEP < 5 cm H2O). Overall, participants were four times more likely to deliver target breaths and one-third less likely to deliver unacceptable breaths using the FIR compared to the SIR. When comparing device performance, a 44% increase in the proportions of target breaths and a 40.4% decrease in unacceptable breaths using the FIR were observed (P < 0.0001 for both). Hand ventilation during patient transport is superior using the FIR compared to the SIR to achieve target ventilatory goals and avoid unacceptable ventilatory cycles. © 2014 John Wiley & Sons Ltd.

Management and outcome of mechanically ventilated neurologic patients.

PubMed

Pelosi, Paolo; Ferguson, Niall D; Frutos-Vivar, Fernando; Anzueto, Antonio; Putensen, Christian; Raymondos, Konstantinos; Apezteguia, Carlos; Desmery, Pablo; Hurtado, Javier; Abroug, Fekri; Elizalde, José; Tomicic, Vinko; Cakar, Nahit; Gonzalez, Marco; Arabi, Yaseen; Moreno, Rui; Esteban, Andres

2011-06-01

To describe and compare characteristics, ventilatory practices, and associated outcomes among mechanically ventilated patients with different types of brain injury and between neurologic and nonneurologic patients. Secondary analysis of a prospective, observational, and multicenter study on mechanical ventilation. Three hundred forty-nine intensive care units from 23 countries. We included 552 mechanically ventilated neurologic patients (362 patients with stroke and 190 patients with brain trauma). For comparison we used a control group of 4,030 mixed patients who were ventilated for nonneurologic reasons. None. We collected demographics, ventilatory settings, organ failures, and complications arising during ventilation and outcomes. Multivariate logistic regression analysis was performed with intensive care unit mortality as the dependent variable. At admission, a Glasgow Coma Scale score ≤8 was observed in 68% of the stroke, 77% of the brain trauma, and 29% of the nonneurologic patients. Modes of ventilation and use of a lung-protective strategy within the first week of mechanical ventilation were similar between groups. In comparison with nonneurologic patients, patients with neurologic disease developed fewer complications over the course of mechanical ventilation with the exception of a higher rate of ventilator-associated pneumonia in the brain trauma cohort. Neurologic patients showed higher rates of tracheotomy and longer duration of mechanical ventilation. Mortality in the intensive care unit was significantly (p < .001) higher in patients with stroke (45%) than in brain trauma (29%) and nonneurologic disease (30%). Factors associated with mortality were: stroke (in comparison to brain trauma), Glasgow Coma Scale score on day 1, and severity at admission in the intensive care unit. In our study, one of every five mechanically ventilated patients received this therapy as a result of a neurologic disease. This cohort of patients showed a higher mortality rate than nonneurologic patients despite a lower incidence of extracerebral organ dysfunction.

Ventilatory gas exchange and early response to cardiac resynchronization therapy.

PubMed

Kim, Chul-Ho; Olson, Lyle J; Shen, Win K; Cha, Yong-Mei; Johnson, Bruce D

2015-11-01

Cardiac resynchronization therapy (CRT) is an accepted intervention for chronic heart failure (HF), although approximately 30% of patients are non-responders. The purpose of this study was to determine whether exercise respiratory gas exchange obtained before CRT implantation predicts early response to CRT. Before CRT implantation, patients were assigned to either a mild-moderate group (Mod G, n = 33, age 67 ± 10 years) or a moderate-severe group (Sev G, n = 31, age 67 ± 10 years), based on abnormalities in exercise gas exchange. Severity of impaired gas exchange was based on a score from the measures of VE/VCO(2) slope, resting PETCO(2) and change of PETCO(2) from resting to peak. All measurements were performed before and 3 to 4 months after CRT implantation. Although Mod G did not have improved gas exchange (p > 0.05), Sev G improved significantly (p < 0.05) post-CRT. In addition, Mod G did not show improved right ventricular systolic pressure (RSVP; pre vs post: 37 ± 14 vs 36 ± 11 mm Hg, p > 0.05), yet Sev G showed significantly improved RVSP, by 23% (50 ± 14 vs 42 ± 12 mm Hg, p < 0.05). Both groups had improved left ventricular ejection fraction (p < 0.05), New York Heart Association class (p < 0.05) and quality of life (p < 0.05), but no significant differences were observed between groups (p > 0.05). No significant changes were observed in brain natriuretic peptide in either group post-CRT. Based on pre-CRT implantation ventilatory gas exchange, subjects with the most impaired values appeared to have more improvement post-CRT, possibly associated with a decrease in RVSP. Copyright © 2015 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

Pulmonary hypertension and ventilation during exercise: Role of the pre-capillary component.

PubMed

Caravita, Sergio; Faini, Andrea; Deboeck, Gael; Bondue, Antoine; Naeije, Robert; Parati, Gianfranco; Vachiéry, Jean-Luc

2017-07-01

Excessive exercise-induced hyperventilation and high prevalence of exercise oscillatory breathing (EOB) are present in patients with post-capillary pulmonary hypertension (PH) complicating left heart disease (LHD). Patients with pre-capillary PH have even higher hyperventilation but no EOB. We sought to determine the impact of a pre-capillary component of PH on ventilatory response to exercise in patients with PH and left heart disease. We retrospectively compared patients with idiopathic or heritable pulmonary arterial hypertension (PAH, n = 29), isolated post-capillary PH (IpcPH, n = 29), and combined post- and pre-capillary PH (CpcPH, n = 12). Diastolic pressure gradient (DPG = diastolic pulmonary artery pressure - pulmonary wedge pressure) was used to distinguish IpcPH (DPG <7 mm Hg) from CpcPH (DPG ≥7 mm Hg). Pulmonary vascular resistance (PVR) was higher in PAH, intermediate in CpcPH, and low in IpcPH. All patients with CpcPH but 1 had PVR >3 Wood unit. Exercise-induced hyperventilation (high minute ventilation over carbon dioxide production, low end-tidal carbon dioxide) was marked in PAH, intermediate in CpcPH, and low in IpcPH (p < 0.001) and correlated with DPG and PVR. Prevalence of EOB decreased from IpcPH to CpcPH to PAH (p < 0.001). Patients with CpcPH may have worse hemodynamics than patients with IpcPH and distinct alterations of ventilatory control, consistent with more exercise-induced hyperventilation and less EOB. This might be explained at least in part by the presence and extent of pulmonary vascular disease. Copyright © 2017 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

Postural control after a prolonged treadmill run at individual ventilatory and anaerobic threshold.

PubMed

Guidetti, Laura; Franciosi, Emanuele; Gallotta, Maria Chiara; Emerenziani, Gian Pietro; Baldari, Carlo

2011-01-01

The objective of the study was to verify whether young males' balance was affected by 30min prolonged treadmill running (TR) at individual ventilatory (IVT) and anaerobic (IAT) thresholds in recovery time. The VO2max, IAT and IVT during an incremental TR were determined. Mean displacement amplitude (Acp) and velocity (Vcp) of center of pressure were recorded before (pre) and after (0min post; 5min post; and 10min post) prolonged TR at IAT and IVT, through posturographic trials performed with eyes open (EO) and closed (EC). Significant differences between IVT and IAT for Vcp, between EO and EC for Acp and Vcp, were observed. The IAT induced higher destabilizing effect when postural trials were performed with EC. The IVT intensity produced also a destabilizing effect on postural control immediately after exercise. An impairment of postural control after prolonged treadmill running exercise at IVT and IAT intensity was showed. However, destabilizing effect on postural control disappeared within 10min after IAT intensity and within 5min after IVT intensity. Key pointsTo verify whether young males' balance was affected by 30min prolonged treadmill running at individual ventilatory and anaerobic thresholds in recovery time.Mean displacement amplitude and velocity of foot pressure center were recorded before and after prolonged treadmill running at individual ventilatory and anaerobic thresholds, through posturographic trials performed with eyes open and closed.Destabilizing effect on postural control disappeared within 10min post individual anaerobic threshold, and within 5min post individual ventilatory threshold.

Impact of anaemia on lung function and exercise capacity in patients with stable severe chronic obstructive pulmonary disease.

PubMed

Guo, Jian; Zheng, Cong; Xiao, Qiang; Gong, Sugang; Zhao, Qinhua; Wang, Lan; He, Jing; Yang, Wenlan; Shi, Xue; Sun, Xingguo; Liu, Jinming

2015-10-08

This study intended to search for potential correlations between anaemia in patients with severe chronic obstructive pulmonary disease (COPD; GOLD stage III) and pulmonary function at rest, exercise capacity as well as ventilatory efficiency, using pulmonary function test (PFT) and cardiopulmonary exercise testing (CPET). The study was undertaken at Shanghai Pulmonary Hospital, a tertiary-level centre affiliated to Tongji University. It caters to a large population base within Shanghai and referrals from centres in other cities as well. 157 Chinese patients with stable severe COPD were divided into 2 groups: the anaemia group (haemoglobin (Hb) <12.0 g/dL for males, and <11 g/dL for females (n=48)) and the non-anaemia group (n=109). Arterial blood gas, PFT and CPET were tested in all patients. (1) Diffusing capacity for carbon monoxide (DLCO) corrected by Hb was significantly lower in the anaemia group ((15.3±1.9) mL/min/mm Hg) than in the non-anaemia group ((17.1±2.1) mL/min/mm Hg) (p<0.05). A significant difference did not exist in the level of forced expiratory volume in 1 s (FEV1), FEV1%pred, FEV1/forced vital capacity (FVC), inspiratory capacity (IC), residual volume (RV), total lung capacity (TLC) and RV/TLC (p>0.05). (2) Peak Load, Peak oxygen uptake (VO2), Peak VO2%pred, Peak VO2/kg, Peak O2 pulse and the ratio of VO2 increase to WR increase (ΔVO2/ΔWR) were significantly lower in the anaemia group (p<0.05); however, Peak minute ventilation (VE), Lowest VE/carbon dioxide output (VCO2) and Peak dead space/tidal volume ratio (VD/VT) were similar between the 2 groups (p>0.05). (3) A strong positive correlation was found between Hb concentration and Peak VO2 in patients with anaemia (r=0.702, p<0.01). Anaemia has a negative impact on gas exchange and exercise tolerance during exercise in patients with severe COPD. The decrease in amplitude of Hb levels is related to the quantity of oxygen uptake. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

WE-AB-202-04: Statistical Evaluation of Lung Function Using 4DCT Ventilation Imaging: Proton Therapy VS IMRT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Q; Zhang, M; Chen, T

Purpose: Variation in function of different lung regions has been ignored so far for conventional lung cancer treatment planning, which may lead to higher risk of radiation induced lung disease. 4DCT based lung ventilation imaging provides a novel yet convenient approach for lung functional imaging as 4DCT is taken as routine for lung cancer treatment. Our work aims to evaluate the impact of accounting for spatial heterogeneity in lung function using 4DCT based lung ventilation imaging for proton and IMRT plans. Methods: Six patients with advanced stage lung cancer of various tumor locations were retrospectively evaluated for the study. Protonmore » and IMRT plans were designed following identical planning objective and constrains for each patient. Ventilation images were calculated from patients’ 4DCT using deformable image registration implemented by Velocity AI software based on Jacobian-metrics. Lung was delineated into two function level regions based on ventilation (low and high functional area). High functional region was defined as lung ventilation greater than 30%. Dose distribution and statistics in different lung function area was calculated for patients. Results: Variation in dosimetric statistics of different function lung region was observed between proton and IMRT plans. In all proton plans, high function lung regions receive lower maximum dose (100.2%–108.9%), compared with IMRT plans (106.4%–119.7%). Interestingly, three out of six proton plans gave higher mean dose by up to 2.2% than IMRT to high function lung region. Lower mean dose (lower by up to 14.1%) and maximum dose (lower by up to 9%) were observed in low function lung for proton plans. Conclusion: A systematic approach was developed to generate function lung ventilation imaging and use it to evaluate plans. This method hold great promise in function analysis of lung during planning. We are currently studying more subjects to evaluate this tool.« less

Measuring Ventilatory Activity with Structured Light Plethysmography (SLP) Reduces Instrumental Observer Effect and Preserves Tidal Breathing Variability in Healthy and COPD

PubMed Central

Niérat, Marie-Cécile; Dubé, Bruno-Pierre; Llontop, Claudia; Bellocq, Agnès; Layachi Ben Mohamed, Lila; Rivals, Isabelle; Straus, Christian; Similowski, Thomas; Laveneziana, Pierantonio

2017-01-01

The use of a mouthpiece to measure ventilatory flow with a pneumotachograph (PNT) introduces a major perturbation to breathing (“instrumental/observer effect”) and suffices to modify the respiratory behavior. Structured light plethysmography (SLP) is a non-contact method of assessment of breathing pattern during tidal breathing. Firstly, we validated the SLP measurements by comparing timing components of the ventilatory pattern obtained by SLP vs. PNT under the same condition; secondly, we compared SLP to SLP+PNT measurements of breathing pattern to evaluate the disruption of breathing pattern and breathing variability in healthy and COPD subjects. Measurements were taken during tidal breathing with SLP alone and SLP+PNT recording in 30 COPD and healthy subjects. Measurements included: respiratory frequency (Rf), inspiratory, expiratory, and total breath time/duration (Ti, Te, and Tt). Passing-Bablok regression analysis was used to evaluate the interchangeability of timing components of the ventilatory pattern (Rf, Ti, Te, and Tt) between measurements performed under the following experimental conditions: SLP vs. PNT, SLP+PNT vs. SLP, and SLP+PNT vs. PNT. The variability of different ventilatory variables was assessed through their coefficients of variation (CVs). In healthy: according to Passing-Bablok regression, Rf, TI, TE and TT were interchangeable between measurements obtained under the three experimental conditions (SLP vs. PNT, SLP+PNT vs. SLP, and SLP+PNT vs. PNT). All the CVs describing “traditional” ventilatory variables (Rf, Ti, Te, Ti/Te, and Ti/Tt) were significantly smaller in SLP+PNT condition. This was not the case for more “specific” SLP-derived variables. In COPD: according to Passing-Bablok regression, Rf, TI, TE, and TT were interchangeable between measurements obtained under SLP vs. PNT and SLP+PNT vs. PNT, whereas only Rf, TE, and TT were interchangeable between measurements obtained under SLP+PNT vs. SLP. However, most discrete variables were significantly different between the SLP and SLP+PNT conditions and CVs were significantly lower when COPD patients were assessed in the SLP+PNT condition. Measuring ventilatory activity with SLP preserves resting tidal breathing variability, reduces instrumental observer effect and avoids any disruptions in breathing pattern induced by the use of PNT-mouthpiece-nose-clip combination. PMID:28572773

Measuring Ventilatory Activity with Structured Light Plethysmography (SLP) Reduces Instrumental Observer Effect and Preserves Tidal Breathing Variability in Healthy and COPD.

PubMed

Niérat, Marie-Cécile; Dubé, Bruno-Pierre; Llontop, Claudia; Bellocq, Agnès; Layachi Ben Mohamed, Lila; Rivals, Isabelle; Straus, Christian; Similowski, Thomas; Laveneziana, Pierantonio

2017-01-01

The use of a mouthpiece to measure ventilatory flow with a pneumotachograph (PNT) introduces a major perturbation to breathing ("instrumental/observer effect") and suffices to modify the respiratory behavior. Structured light plethysmography (SLP) is a non-contact method of assessment of breathing pattern during tidal breathing. Firstly, we validated the SLP measurements by comparing timing components of the ventilatory pattern obtained by SLP vs. PNT under the same condition; secondly, we compared SLP to SLP+PNT measurements of breathing pattern to evaluate the disruption of breathing pattern and breathing variability in healthy and COPD subjects. Measurements were taken during tidal breathing with SLP alone and SLP+PNT recording in 30 COPD and healthy subjects. Measurements included: respiratory frequency (R f ), inspiratory, expiratory, and total breath time/duration (Ti, Te, and Tt). Passing-Bablok regression analysis was used to evaluate the interchangeability of timing components of the ventilatory pattern (R f , Ti, Te, and Tt) between measurements performed under the following experimental conditions: SLP vs. PNT, SLP+PNT vs. SLP, and SLP+PNT vs. PNT. The variability of different ventilatory variables was assessed through their coefficients of variation (CVs). In healthy: according to Passing-Bablok regression, Rf, TI, TE and TT were interchangeable between measurements obtained under the three experimental conditions (SLP vs. PNT, SLP+PNT vs. SLP, and SLP+PNT vs. PNT). All the CVs describing "traditional" ventilatory variables (R f , Ti, Te, Ti/Te, and Ti/Tt) were significantly smaller in SLP+PNT condition. This was not the case for more "specific" SLP-derived variables. In COPD: according to Passing-Bablok regression, Rf, TI, TE, and TT were interchangeable between measurements obtained under SLP vs. PNT and SLP+PNT vs. PNT, whereas only Rf, TE, and TT were interchangeable between measurements obtained under SLP+PNT vs. SLP. However, most discrete variables were significantly different between the SLP and SLP+PNT conditions and CVs were significantly lower when COPD patients were assessed in the SLP+PNT condition. Measuring ventilatory activity with SLP preserves resting tidal breathing variability, reduces instrumental observer effect and avoids any disruptions in breathing pattern induced by the use of PNT-mouthpiece-nose-clip combination.

Positive end-expiratory pressure at minimal respiratory elastance represents the best compromise between mechanical stress and lung aeration in oleic acid induced lung injury.

PubMed

Carvalho, Alysson Roncally S; Jandre, Frederico C; Pino, Alexandre V; Bozza, Fernando A; Salluh, Jorge; Rodrigues, Rosana; Ascoli, Fabio O; Giannella-Neto, Antonio

2007-01-01

Protective ventilatory strategies have been applied to prevent ventilator-induced lung injury in patients with acute lung injury (ALI). However, adjustment of positive end-expiratory pressure (PEEP) to avoid alveolar de-recruitment and hyperinflation remains difficult. An alternative is to set the PEEP based on minimizing respiratory system elastance (Ers) by titrating PEEP. In the present study we evaluate the distribution of lung aeration (assessed using computed tomography scanning) and the behaviour of Ers in a porcine model of ALI, during a descending PEEP titration manoeuvre with a protective low tidal volume. PEEP titration (from 26 to 0 cmH2O, with a tidal volume of 6 to 7 ml/kg) was performed, following a recruitment manoeuvre. At each PEEP, helical computed tomography scans of juxta-diaphragmatic parts of the lower lobes were obtained during end-expiratory and end-inspiratory pauses in six piglets with ALI induced by oleic acid. The distribution of the lung compartments (hyperinflated, normally aerated, poorly aerated and non-aerated areas) was determined and the Ers was estimated on a breath-by-breath basis from the equation of motion of the respiratory system using the least-squares method. Progressive reduction in PEEP from 26 cmH2O to the PEEP at which the minimum Ers was observed improved poorly aerated areas, with a proportional reduction in hyperinflated areas. Also, the distribution of normally aerated areas remained steady over this interval, with no changes in non-aerated areas. The PEEP at which minimal Ers occurred corresponded to the greatest amount of normally aerated areas, with lesser hyperinflated, and poorly and non-aerated areas. Levels of PEEP below that at which minimal Ers was observed increased poorly and non-aerated areas, with concomitant reductions in normally inflated and hyperinflated areas. The PEEP at which minimal Ers occurred, obtained by descending PEEP titration with a protective low tidal volume, corresponded to the greatest amount of normally aerated areas, with lesser collapsed and hyperinflated areas. The institution of high levels of PEEP reduced poorly aerated areas but enlarged hyperinflated ones. Reduction in PEEP consistently enhanced poorly or non-aerated areas as well as tidal re-aeration. Hence, monitoring respiratory mechanics during a PEEP titration procedure may be a useful adjunct to optimize lung aeration.

Hypoxic ventilatory sensitivity in men is not reduced by prolonged hyperoxia (Predictive Studies V and VI)

NASA Technical Reports Server (NTRS)

Gelfand, R.; Lambertsen, C. J.; Clark, J. M.; Hopkin, E.

1998-01-01

Potential adverse effects on the O2-sensing function of the carotid body when its cells are exposed to toxic O2 pressures were assessed during investigations of human organ tolerance to prolonged continuous and intermittent hyperoxia (Predictive Studies V and VI). Isocapnic hypoxic ventilatory responses (HVR) were determined at 1.0 ATA before and after severe hyperoxic exposures: 1) continuous O2 breathing at 1.5, 2.0, and 2.5 ATA for 17.7, 9.0, and 5.7 h and 2) intermittent O2 breathing at 2.0 ATA (30 min O2-30 min normoxia) for 14.3 O2 h within 30-h total time. Postexposure curvature of HVR hyperbolas was not reduced compared with preexposure controls. The hyperbolas were temporarily elevated to higher ventilations than controls due to increments in respiratory frequency that were proportional to O2 exposure time, not O2 pressure. In humans, prolonged hyperoxia does not attenuate the hypoxia-sensing function of the peripheral chemoreceptors, even after exposures that approach limits of human pulmonary and central nervous system O2 tolerance. Current applications of hyperoxia in hyperbaric O2 therapy and in subsea- and aerospace-related operations are guided by and are well within these exposure limits.

Contribution of peripheral and central chemoreceptors to sympatho‐excitation in heart failure

PubMed Central

Toledo, Camilo; Andrade, David C.; Lucero, Claudia; Schultz, Harold D.; Marcus, Noah; Retamal, Mauricio; Madrid, Carlos

2016-01-01

Abstract Chronic heart failure (CHF) is a major public health problem. Tonic hyper‐activation of sympathetic neural outflow is commonly observed in patients with CHF. Importantly, sympatho‐excitation in CHF exacerbates its progression and is strongly related to poor prognosis and high mortality risk. Increases in both peripheral and central chemoreflex drive are considered markers of the severity of CHF. The principal peripheral chemoreceptors are the carotid bodies (CBs) and alteration in their function has been described in CHF. Mainly, during CHF the CB chemosensitivity is enhanced leading to increases in ventilation and sympathetic outflow. In addition to peripheral control of breathing, central chemoreceptors (CCs) are considered a dominant mechanism in ventilatory regulation. Potentiation of the ventilatory and sympathetic drive in response to CC activation has been shown in patients with CHF as well as in animal models. Therefore, improving understanding of the contribution of the peripheral and central chemoreflexes to augmented sympathetic discharge in CHF could help in developing new therapeutic approaches intended to attenuate the progression of CHF. Accordingly, the main focus of this review is to discuss recent evidence that peripheral and central chemoreflex function are altered in CHF and that they contribute to autonomic imbalance and progression of CHF. PMID:27218485

Morphology and ventilatory function of gills in the carpet shark family Parascylliidae (Elasmobranchii, Orectolobiformes).

PubMed

Goto, Tomoaki; Shiba, Yojiro; Shibagaki, Kazuhiro; Nakaya, Kazuhiro

2013-06-01

We examined gill morphology and ventilatory function in the carpet shark family Parascylliidae using 14 preserved specimens of Parascyllium ferrugineum, P. variolatum, P. collare and Cirrhoscyllium japonicum, and two live specimens of P. ferrugineum and P. variolatum. Morphological examinations revealed eight morphological characteristics related to the fifth gill, based on comparisons with other elasmobranchs, viz. large fifth gill slit without gill filaments, anatomical modifications in the fourth ceratobranchial cartilage and coraco-branchialis muscle, and the hypaxialis muscle associated with the fifth gill arch. Ventilation examinations using dyed seawater and prey items showed different water flows through the gill slits for respiration and prey-capture actions. For respiration, water sucked into the mouth was expelled equally through the first to fourth gill slits via a "double-pump" action, there being no involvement of the fifth gill slit. In prey-capture, however, water sucked into the mouth was discharged only via the widely opened fifth gill slit. This form of water flow is similar to that in other benthic suction-feeding sharks (e.g., Chiloscyllium plagiosum), except for the active water discharge by wide expansion and contraction of the fifth parabranchial cavity. The latter is dependent upon the morphological modifications of the fourth and fifth gill arches, derived phylogenetically as a mechanistic suction specialization in Parascylliidae.

[Analysis in pulmonary ventilatory function from 100 patients with ano-rectal diseases caused by deficiency of qi].

PubMed

Wang, W

1999-03-01

To explore the pathogenesis of ano-rectal diseases caused by deficiency of Qi, which is correlated with obstruction of pulmonary ventilation. The pulmonary ventilatory function was measured in 100 patients with the internal piles, the interno-external hemorrhoid and prolapse of rectum, the prolapse of anus was the principal symptom of them. Data from the 100 patients showed that 67% of them were diagnosed with the obstruction of pulmonary ventilation, the ratio was far less in the health control group. FEV 1.0 (mean +/- s) (2011.65 +/- 875) ml, MMF (1.84 +/- 1.24) L/s and PEF (2.34 +/- 1.51) L/s in male patients, (1551.54 +/- 514) ml, (1.57 +/- 0.62) L/s and (1.85 +/- 0.92) L/s in female patients, but those values were higher in the control than in the patients. The statistical analysis was performed and the difference was significant between patients and the control group (P < 0.01). The patients with ano-rectal diseases caused by deficiency of Qi accompanied with obstruction of pulmonary ventilation in different degree and varied sorts, it confirmed that the pathogenesis of ano-rectal diseases caused by deficiency of Qi is related with "sinking of pectoral Qi".

Tetrodotoxin as a Tool to Elucidate Sensory Transduction Mechanisms: The Case for the Arterial Chemoreceptors of the Carotid Body

PubMed Central

Rocher, Asuncion; Caceres, Ana Isabel; Obeso, Ana; Gonzalez, Constancio

2011-01-01

Carotid bodies (CBs) are secondary sensory receptors in which the sensing elements, chemoreceptor cells, are activated by decreases in arterial PO2 (hypoxic hypoxia). Upon activation, chemoreceptor cells (also known as Type I and glomus cells) increase their rate of release of neurotransmitters that drive the sensory activity in the carotid sinus nerve (CSN) which ends in the brain stem where reflex responses are coordinated. When challenged with hypoxic hypoxia, the physiopathologically most relevant stimulus to the CBs, they are activated and initiate ventilatory and cardiocirculatory reflexes. Reflex increase in minute volume ventilation promotes CO2 removal from alveoli and a decrease in alveolar PCO2 ensues. Reduced alveolar PCO2 makes possible alveolar and arterial PO2 to increase minimizing the intensity of hypoxia. The ventilatory effect, in conjunction the cardiocirculatory components of the CB chemoreflex, tend to maintain an adequate supply of oxygen to the tissues. The CB has been the focus of attention since the discovery of its nature as a sensory organ by de Castro (1928) and the discovery of its function as the origin of ventilatory reflexes by Heymans group (1930). A great deal of effort has been focused on the study of the mechanisms involved in O2 detection. This review is devoted to this topic, mechanisms of oxygen sensing. Starting from a summary of the main theories evolving through the years, we will emphasize the nature and significance of the findings obtained with veratridine and tetrodotoxin (TTX) in the genesis of current models of O2-sensing. PMID:22363245

Carotid Body Ablation Abrogates Hypertension and Autonomic Alterations Induced by Intermittent Hypoxia in Rats.

PubMed

Del Rio, Rodrigo; Andrade, David C; Lucero, Claudia; Arias, Paulina; Iturriaga, Rodrigo

2016-08-01

Chronic intermittent hypoxia (CIH), the main feature of obstructive sleep apnea, enhances carotid body (CB) chemosensory responses to hypoxia and produces autonomic dysfunction, cardiac arrhythmias, and hypertension. We tested whether autonomic alterations, arrhythmogenesis, and the progression of hypertension induced by CIH depend on the enhanced CB chemosensory drive, by ablation of the CB chemoreceptors. Male Sprague-Dawley rats were exposed to control (Sham) conditions for 7 days and then to CIH (5% O2, 12/h 8 h/d) for a total of 28 days. At 21 days of CIH exposure, rats underwent bilateral CB ablation and then exposed to CIH for 7 additional days. Arterial blood pressure and ventilatory chemoreflex response to hypoxia were measured in conscious rats. In addition, cardiac autonomic imbalance, cardiac baroreflex gain, and arrhythmia score were assessed during the length of the experiments. In separate experimental series, we measured extracellular matrix remodeling content in cardiac atrial tissue and systemic oxidative stress. CIH induced hypertension, enhanced ventilatory response to hypoxia, induced autonomic imbalance toward sympathetic preponderance, reduced baroreflex gain, and increased arrhythmias and atrial fibrosis. CB ablation normalized blood pressure, reduced ventilatory response to hypoxia, and restored cardiac autonomic and baroreflex function. In addition, CB ablation reduced the number of arrhythmias, but not extracellular matrix remodeling or systemic oxidative stress, suggesting that reductions in arrhythmia incidence during CIH were related to normalization of cardiac autonomic balance. Present results show that autonomic alterations induced by CIH are critically dependent on the CB and support a main role for the CB in the CIH-induced hypertension. © 2016 American Heart Association, Inc.

Hyperventilation and blood acid-base balance in hypercapnia exposed red drum (Sciaenops ocellatus).

PubMed

Ern, Rasmus; Esbaugh, Andrew J

2016-05-01

Hyperventilation is a common response in fish exposed to elevated water CO2. It is believed to lessen the respiratory acidosis associated with hypercapnia by lowering arterial PCO2, but the contribution of hyperventilation to blood acid-base compensation has yet to be quantified. Hyperventilation may also increase the flux of irons across the gill epithelium and the cost of osmoregulation, owing to the osmo-respiratory compromise. Therefore, hypercapnia exposed fish may increase standard metabolic rate (SMR) leaving less energy for physiological functions such as foraging, migration, growth and reproduction. Here we show that gill ventilation, blood PCO2 and total blood [CO2] increased in red drum (Sciaenops ocellatus) exposed to 1000 and 5000 µatm water CO2, and that blood PCO2 and total blood [CO2] decrease in fish during hypoxia induced hyperventilation. Based on these results we estimate the ventilatory contributions to total acid-base compensation in 1000 and 5000 µatm water CO2. We find that S. ocellatus only utilize a portion of its ventilatory capacity to reduce the acid-base disturbance in 1000 µatm water CO2. SMR was unaffected by both salinity and hypercapnia exposure indicating that the cost of osmoregulation is small relative to SMR, and that the lack of increased ventilation in 1000 µatm water CO2 despite the capacity to do so is not due to an energetic tradeoff between acid-base balance and osmoregulation. Therefore, while ocean acidification may impact ventilatory parameters, there will be little impact on the overall energy budget of S. ocellatus.

CD16-positive circulating monocytes and fibrotic manifestations of systemic sclerosis.

PubMed

Lescoat, Alain; Lecureur, Valérie; Roussel, Mikael; Sunnaram, Béatrice Ly; Ballerie, Alice; Coiffier, Guillaume; Jouneau, Stéphane; Fardel, Olivier; Fest, Thierry; Jégo, Patrick

2017-07-01

The objective of this study is to assess the association of clinical manifestations of systemic sclerosis (SSc) with the absolute count of circulating blood monocyte subpopulations according to their membrane expression of CD16. Forty-eight consecutive patients fulfilling the 2013 ACR/EULAR classification criteria for SSc were included in this cross-sectional study. CD16+ monocyte absolute count was defined by flow cytometry and confronted to the clinical characteristics of SSc patients. Twenty-three healthy donors (HD) were randomly selected for comparison. SSc patients had an increased number of total circulating blood monocytes compared to HD (p < 0.001). The CD16- subpopulation absolute count was increased in SSc patients compared to HD (p < 0.001) but was similar in limited SSc (lSSc) and diffuse SSc (dSSc). On the contrary, the CD16+ population absolute count was increased in dSSc compared to both HD and lSSc patients (dSSc 0.071 Giga/L (±0.034) vs HD 0.039 Giga/L (±0.030), p < 0.01, and dSSc 0.071 Giga/L (±0.034) vs lSSc 0.048 Giga/L (±0.024), p < 0.05). The CD16+ monocyte subpopulation absolute count was significantly correlated with the severity of skin fibrosis evaluated by the modified Rodnan skin score (p < 0.001). The CD16+ monocyte subpopulation was also associated with pulmonary fibrosis (p < 0.05), with the severity of the restrictive ventilatory defect evaluated by total lung capacity (p < 0.05) and with the pulmonary function impairment reflected by diffusing capacity of the lungs for carbon monoxyde measures (p < 0.01). These results suggest that CD16+ monocytes are associated with the main fibrotic manifestations of SSc and their role in the pathogenesis of fibrosis in this autoimmune disorder should therefore be further considered.

Divers revisited: The ventilatory response to carbon dioxide in experienced scuba divers.

PubMed

Earing, Christopher Matthew Norton; McKeon, Damian John; Kubis, Hans-Peter

2014-05-01

To investigate the ventilatory response to CO2 in hyperoxia, hypoxia, and during exercise amongst experienced scuba divers and matched controls. Two studies were performed. The first investigated the CO2 sensitivity in rest and exercise using CO2 rebreathing in hyperoxia at a workload typical for diving with divers (n = 11) and controls (n = 11). The second study examined the respiratory drive of divers (n = 10) and controls (n = 10) whilst breathing four different gas mixtures balanced with N2 (ambient air; 25% O2/6% CO2; 13% O2; 13% O2/6% CO2) to assess the combined response to hypercapnia and moderate hypoxia. Exercise at a load typical for diving was found to have no effect on the ventilatory sensitivity to CO2 in divers (rest: 1.49 ± 0.33; exercise: 1.22 ± 0.55 [l/min × mmHg(-1)]) and controls (rest: 2.08 ± 0.71; exercise: 2.05 ± 0.98 [l/min × mmHg(-1)]) while differences in sensitivity remained between the groups. Inhalation of the four gas mixtures revealed the tested oxygen pressures caused no significant alteration in the ventilatory sensitivity to CO2 in divers and controls. Experienced divers possess a lower ventilatory response to CO2 which was not affected by exercise or the tested oxygen pressures suggesting a dominant adaptation of central CO2 sensitivity. Copyright © 2014 Elsevier Ltd. All rights reserved.

Cold stimulates the behavioral response to hypoxia in newborn mice.

PubMed

Bollen, Bieke; Bouslama, Myriam; Matrot, Boris; Rotrou, Yann; Vardon, Guy; Lofaso, Frédéric; Van den Bergh, Omer; D'Hooge, Rudi; Gallego, Jorge

2009-05-01

In newborns, hypoxia elicits increased ventilation, arousal followed by defensive movements, and cries. Cold is known to affect the ventilatory response to hypoxia, but whether it affects the arousal response remains unknown. The aim of the present study was to assess the effects of cold on the ventilatory and arousal responses to hypoxia in newborn mice. We designed an original platform measuring noninvasively and simultaneously the breathing pattern by whole body plethysmography, body temperature by infrared thermography, as well as motor and ultrasonic vocal (USV) responses. Six-day-old mice were exposed twice to 10% O(2) for 3 min at either cold temperature (26 degrees C) or thermoneutrality (33 degrees C). At 33 degrees C, hypoxia elicited a marked increase in ventilation followed by a small ventilatory decline, small motor response, and almost no USVs. Body temperature was not influenced by hypoxia, and oxygen consumption (Vo(2)) displayed minimal changes. At 26 degrees C, hypoxia elicited a slight increase in ventilation with a large ventilatory decline and a large drop of Vo(2). This response was accompanied by marked USV and motor responses. Hypoxia elicited a small decrease in temperature after the return to normoxia, thus precluding any causal influence on the motor and USV responses to hypoxia. In conclusion, cold stimulated arousal and stress responses to hypoxia, while depressing hypoxic hyperpnea. Arousal is an important defense mechanism against sleep-disordered breathing. The dissociation between ventilatory and behavioral responses to hypoxia suggests that deficits in the arousal response associated with sleep breathing disorders cannot be attributed to a depressed hypoxic response.

Polycythemia and high levels of erythropoietin in blood and brain blunt the hypercapnic ventilatory response in adult mice.

PubMed

Menuet, Clément; Khemiri, Hanan; de la Poëze d'Harambure, Théodora; Gestreau, Christian

2016-05-15

Changes in arterial Po2, Pco2, and pH are the strongest stimuli sensed by peripheral and central chemoreceptors to adjust ventilation to the metabolic demand. Erythropoietin (Epo), the main regulator of red blood cell production, increases the hypoxic ventilatory response, an effect attributed to the presence of Epo receptors in both carotid bodies and key brainstem structures involved in integration of peripheral inputs and control of breathing. However, it is not known whether Epo also has an effect on the hypercapnic chemoreflex. In a first attempt to answer this question, we tested the hypothesis that Epo alters the ventilatory response to increased CO2 levels. Basal ventilation and hypercapnic ventilatory response (HCVR) were recorded from control mice and from two transgenic mouse lines constitutively expressing high levels of human Epo in brain only (Tg21) or in brain and plasma (Tg6), the latter leading to polycythemia. To tease apart the potential effects of polycythemia and levels of plasma Epo in the HCVR, control animals were injected with an Epo analog (Aranesp), and Tg6 mice were treated with the hemolytic agent phenylhydrazine after splenectomy. Ventilatory parameters measured by plethysmography in conscious mice were consistent with data from electrophysiological recordings in anesthetized animals and revealed a blunted HCVR in Tg6 mice. Polycythemia alone and increased levels of plasma Epo blunt the HCVR. In addition, Tg21 mice with an augmented level of cerebral Epo also had a decreased HCVR. We discuss the potential implications of these findings in several physiopathological conditions. Copyright © 2016 the American Physiological Society.

EFFECTS OF INDUCED RESPIRATORY CHANGES ON CARDIAC, VENTILATORY, AND THERMOREGULATORY PARAMETERS IN HEALTHY SPRAGUE-DAWLEY RATS

EPA Science Inventory

EFFECTS OF INDUCED RESPIRATORY CHANGES ON CARDIAC, VENTILATORY, AND THERMOREGULATORY PARAMETERS IN HEALTHY SPRAGUE-DAWLEY RATS. LB Wichers1, WH Rowan2, DL Costa2, MJ Campen3 and WP Watkinson2 1UNC SPH, Chapel Hill, NC, USA; 2USEPA, ORD/NHEERL/ETD/PTB, RTP, NC, USA; 3LRRI, A...

Control of ventilation during intravenous CO2 loading in the awake dog.

PubMed

Stremel, R W; Huntsman, D J; Casaburi, R; Whipp, B J; Wasserman, K

1978-02-01

The ventilatory response to venous CO2 loading and its effect on arterial CO2 tension was determined in five awake dogs. Blood, 200-500 ml/min, was diverted from a catheter in the right common carotid artery through a membrane gas exchanger and returned to the right jugular vein. CO2 loading was accomplished by changing the gas ventilating the gas exchanger from a mixture of 5% CO2 in air to 100% CO2. The ventilatory responses to this procedure were compared with those resulting from increased inspired CO2 concentrations (during which ventilation of the gas exchanger with the air and 5% CO2 mixture continued). The ventilatory response to each form of CO2 loading was computed as deltaVE/deltaPaco9. The mean ventilatory response to airway CO2 loading was 1.61 1/min per Torr PaCO2. The mean response for the venous CO2 loading was significantly higher and not significantly different from "infinite" CO2 sensitivity (i.e., isocapnic response). The results provide further evidence for a CO2-linked hyperpnea, not mediated by significant changes in mean arterial PCO2.

Anaerobic threshold determination through ventilatory and electromyographics parameters.

PubMed

Gassi, E R; Bankoff, A D P

2010-01-01

The aim of present study was to compare the alterations in electromyography signs with Ventilatory Threshold (VT). Had been part of the study eight men, amateur cyclists and triathletes (25.25 +/- 6.96 years), that they had exercised themselves in a mechanical cicloergometer, a cadence of 80 RPM and with the increased intensity being in 25 W/min until the exhaustion. The VT was determined by a non-linear increase in VE/VO2 without any increase in VE/VCO2 and compared with the intensity corresponding to break point of amplitude EMG sign during the incremental exercise. The EMG--Fatigue Threshold (FT) and Ventilatory Threshold (VT) parameters used were the power, the time, absolute and relative VO2, ventilation (VE), the heart hate (HH) and the subjective perception of the effort. The results had not shown to difference in none of the variable selected for the corresponding intensity to VT and FT--EMG of the muscles lateralis vastus and femoris rectus. The parameters used in the comparison between the electromyographic indicators and ventilatory were the load, the time, absolute VO2 and relative to corporal mass, to ventilation (VE), the heart frequency (HH) and the Subjective Perception of the Effort (SPE).

Changes in Ventilatory Response to Exercise in Trained Athletes: Respiratory Physiological Benefits Beyond Cardiovascular Performance.

PubMed

di Paco, Adriano; Dubé, Bruno-Pierre; Laveneziana, Pierantonio

2017-05-01

The beneficial impact of an 8-month competitive season on the ventilatory profile response to exercise in soccer players has never been evaluated. Ventilatory profile (evaluated by determining individual tidal volume [V T ] relative to minute ventilation [V E ] inflection points during exercise) and metabolic responses to incremental exercise were evaluated in 2 professional soccer teams before and after an 8-month competitive season. No differences between teams in anthropometric characteristics or in resting cardiopulmonary variables, included oxygen uptake (VO 2 ) and heart rate (HR), before and during the competitive season were found. At iso-speed, there were overall improvements in carbon dioxide output (VCO 2 ), V E /VO 2 , V E /VCO 2 , V E and respiratory frequency (fR) during the season. The V T /V E inflection points 1 and 2 occurred with greater exercise time, HR, VO 2 , VCO 2 , V E and V T during the competitive season. Despite very high baseline performance and a negligible improvement in VO 2 , an 8-month competitive season improved ventilatory profile response to exercise in elite athletes. Copyright © 2016 SEPAR. Publicado por Elsevier España, S.L.U. All rights reserved.

Monitoring respiratory muscles.

PubMed

Nava, S

1998-12-01

The respiratory system consists of two main parts, the lung and the ventilatory pump. The latter consists of the bony structure of the thorax, the central respiratory controllers, the inspiratory and expiratory muscles, and the nerves innervating these muscles. Respiratory muscle fatigue occurs when respiratory muscle endurance is exceeded. Muscle fatigue is defined as a condition in which there is a reduction in the capacity for developing force and/or velocity of a muscle, resulting from muscle activity, and which is reversible by rest. The respiratory muscles are somewhat difficult to assess and the techniques employed are still relatively primitive. The most important methods of respiratory muscles function assessment are: 1) the vital capacity manoeuvre, which depends on maximum inspiratory and expiratory effort by the muscles and may be a useful indicator of respiratory muscle function; 2) radiological screening has been proposed for the detection of diaphragm paralysis. This may be helpful if the paralysis is unilateral, but bilateral paralysis is difficult to detect; and 3) respiratory muscles strength may be assessed with either voluntary or nonvoluntary manoeuvres. The function of the inspiratory muscles is assessed with 3 voluntary dependent manoeuvres. They are the so called Müller manoeuvre (or maximal inspiratory pressure), the sniff test and the combined test. All these three manoeuvres generate a pressure that is a reflection of complex interactions between several muscle groups since the efforts produce different mechanisms of activity of inspiratory and expiratory muscles. Two techniques are presently employed to assess diaphragm function, not being dependent on the patient's motivation: electrical phrenic nerve stimulation and cervical magnetic stimulation. Since it is less painful, magnetic cervical stimulation overcomes some of the difficulties encountered during electrical stimulation. With these two techniques recordings of diaphragmatic force are possible, and at the same time useful information about the conduction time of both phrenic nerves can be obtained.

Exercise training improves breathing strategy and performance during the six-minute walk test in obese adolescents.

PubMed

Mendelson, Monique; Michallet, Anne-Sophie; Perrin, Claudine; Levy, Patrick; Wuyam, Bernard; Flore, Patrice

2014-08-15

We aimed to examine ventilatory responses during the six-minute walk test in healthy-weight and obese adolescents before and after exercise training. Twenty obese adolescents (OB) (age: 14.5±1.7 years; BMI: 34.0±4.7kg·m(-2)) and 20 age and gender-matched healthy-weight adolescents (HW) (age: 15.5±1.5 years; BMI: 19.9±1.4kg·m(-2)) completed six-minute walk test during which breath-by-breath gas analysis and expiratory flow limitation (expFL) were measured. OB participated in a 12-week exercise-training program. Comparison between HW and OB participants showed lower distance achieved during the 6MWT in OB (-111.0m, 95%CI: -160.1 to 62.0, p<0.05) and exertional breathlessness was greater (+0.78 a.u., 95%CI: 0.091-3.27, p=0.039) when compared with HW. Obese adolescents breathed at lower lung volumes, as evidenced by lower end expiratory and end inspiratory lung volumes during exercise (p<0.05). Prevalence of expFL (8 OB vs 2 HW, p=0.028) and mean expFL (14.9±21.9 vs 5.32±14.6% VT, p=0.043, in OB and HW) were greater in OB. After exercise training, mean increase in the distance achieved during the 6MWT was 64.5 meters (95%CI: 28.1-100.9, p=0.014) and mean decrease in exertional breathlessness was 1.62 (95%CI: 0.47-2.71, p=0.05). Obese adolescents breathed at higher lung volumes, as evidenced by the increase in end inspiratory lung volume from rest to 6-min exercise (9.9±13.4 vs 20.0±13.6%TLC, p<0.05). Improved performance was associated with improved change in end inspiratory lung volume from rest to 6-min exercise (r=0.65, p=0.025). Our results suggest that exercise training can improve breathing strategy during submaximal exercise in obese adolescents and that this increase is associated with greater exercise performance. Copyright © 2014 Elsevier B.V. All rights reserved.

[Humidifier-associated disease in the general population].

PubMed

Müller-Wening, D; Koschel, D; Stark, W; Sennekamp, H-J

2006-03-10

Recently an increasing number of patients presented with febrile and respiratory symptoms associated with exposure to a new type of domestic ultrasonic humidifier. We report on 14 patients (5 females, 9 males; average age 42.5 17.4 years) with recurrent episodes of fever, cough and dyspnea after repeated exposure to ultrasonic misting fountain at home. A diagnosis of extrinsic allergic alveolitis (humidifier lung: 12 patients) or toxic alveolitis (humidifier fever: 2 patients) was made on the basis of the history and the clinical, radiological, laboratory and immunological findings. 10 patients had a partial respiratory insufficiency at rest or on exercise, 9 had a restrictive ventilatory abnormality. The chest x-ray was abnormal in 7 patients. Of 8 patients in whom computed tomography was done 6 had typical changes of an exogenous allergic alveolitis. Bronchoalveolar lavage revealed lymphocytic alveolitis in 8 patients. In 12 patients bacteria, moulds and/or yeasts were demonstrated in the humidifier fluid which they had used. 13 patients had IgG antibodies to the humidifier fluid. 8 patients were subjected to inhalative challenge tests to their own ultrasonic misting fountain: all of them had positive reactions. These cases demonstrate the potential of ultrasonic humidifying devices to cause illness in the home. In view of their increasing popularity, humidifier lung and humidifier fever should be considered in the differential diagnosis of patients with unexplained pulmonary or flu-like illness with fever.

Partial liquid ventilation: effects of closed breathing systems, heat-and-moisture-exchangers and sodalime absorbers on perfluorocarbon evaporation.

PubMed

Wilms, C T; Schober, P; Kalb, R; Loer, S A

2006-01-01

During partial liquid ventilation perfluorocarbons are instilled into the airways from where they subsequently evaporate via the bronchial system. This process is influenced by multiple factors, such as the vapour pressure of the perfluorocarbons, the instilled volume, intrapulmonary perfluorocarbon distribution, postural positioning and ventilatory settings. In our study we compared the effects of open and closed breathing systems, a heat-and-moisture-exchanger and a sodalime absorber on perfluorocarbon evaporation during partial liquid ventilation. Isolated rat lungs were suspended from a force transducer. After intratracheal perfluorocarbon instillation (10 mL kg(-1)) the lungs were either ventilated with an open breathing system (n = 6), a closed breathing system (n = 6), an open breathing system with an integrated heat-and-moisture-exchanger (n = 6), an open breathing system with an integrated sodalime absorber (n = 6), or a closed breathing system with an integrated heat-and-moisture-exchanger and a sodalime absorber (n = 6). Evaporative perfluorocarbon elimination was determined gravimetrically. When compared to the elimination half-life in an open breathing system (1.2 +/- 0.07 h), elimination half-life was longer with a closed system (6.4 +/- 0.9 h, P 0.05) when compared to a closed system. Evaporative perfluorocarbon loss can be reduced effectively with closed breathing systems, followed by the use of sodalime absorbers and heat-and-moisture-exchangers.

Ventilatory Responses to Hypercapnia during Wakefulness and Sleep in Obese Adolescents With and Without Obstructive Sleep Apnea Syndrome

PubMed Central

Yuan, Haibo; Pinto, Swaroop J.; Huang, Jingtao; McDonough, Joseph M.; Ward, Michelle B.; Lee, Yin N.; Bradford, Ruth M.; Gallagher, Paul R.; Shults, Justine; Konstantinopoulou, Sophia; Samuel, John M.; Katz, Eliot S.; Hua, Shucheng; Tapia, Ignacio E.; Marcus, Carole L.

2012-01-01

Study Objectives: Abnormal ventilatory drive may contribute to the pathophysiology of the childhood obstructive sleep apnea syndrome (OSAS). Concomitant with the obesity epidemic, more adolescents are developing OSAS. However, few studies have specifically evaluated the obese adolescent group. The authors hypothesized that obese adolescents with OSAS would have a blunted hypercapnic ventilatory response (HCVR) while awake and blunted ventilatory responses to carbon dioxide (CO2) during sleep compared with obese and lean adolescents without OSAS. Design: CVR was measured during wakefulness. During nonrapid eye movement (NREM) and rapid eye movement (REM) sleep, respiratory parameters and genioglossal electromyogram were measured during CO2 administration in comparison with room air in obese adolescents with OSAS, obese control study participants, and lean control study participants. Setting: Sleep laboratory. Participants: Twenty-eight obese patients with OSAS, 21 obese control study participants, and 37 lean control study participants. Results: The obese OSAS and obese control groups had a higher HCVR compared with the lean control group during wakefulness. During both sleep states, all 3 groups had a response to CO2; however, the obese OSAS group had lower percentage changes in minute ventilation, inspiratory flow, inspiratory time, and tidal volume compared with the 2 control groups. There were no significance differences in genioglossal activity between groups. Conclusions: HCVR during wakefulness is increased in obese adolescents. Obese adolescents with OSAS have blunted ventilatory responses to CO2 during sleep and do not have a compensatory prolongation of inspiratory time, despite having normal CO2 responsivity during wakefulness. Central drive may play a greater role than upper airway neuromotor tone in adapting to hypercapnia. Citation: Yuan H; Pinto SJ; Huang J; McDonough JM; Ward MB; Lee YN; Bradford RM; Gallagher PR; Shults J; Konstantinopoulou S; Samuel JM; Katz ES; Hua S; Tapia IE; Marcus CL. Ventilatory responses to hypercapnia during wakefulness and sleep in obese adolescents with and without obstructive sleep apnea syndrome. SLEEP 2012;35(9):1257–1267. PMID:22942504

Sinusoidal high-intensity exercise does not elicit ventilatory limitation in chronic obstructive pulmonary disease.

PubMed

Porszasz, Janos; Rambod, Mehdi; van der Vaart, Hester; Rossiter, Harry B; Ma, Shuyi; Kiledjian, Rafi; Casaburi, Richard

2013-06-01

During exercise at critical power (CP) in chronic obstructive pulmonary disease (COPD) patients, ventilation approaches its maximum. As a result of the slow ventilatory dynamics in COPD, ventilatory limitation during supramaximal exercise might be escaped using rapid sinusoidal forcing. Nine COPD patients [age, 60.2 ± 6.9 years; forced expiratory volume in the first second (FEV(1)), 42 ± 17% of predicted; and FEV(1)/FVC, 39 ± 12%] underwent an incremental cycle ergometer test and then four constant work rate cycle ergometer tests; tolerable duration (t(lim)) was recorded. Critical power was determined from constant work rate testing by linear regression of work rate versus 1/t(lim). Patients then completed fast (FS; 60 s period) and slow (SS; 360 s period) sinusoidally fluctuating exercise tests with mean work rate at CP and peak at 120% of peak incremental test work rate, and one additional test at CP; each for a 20 min target. The value of t(lim) did not differ between CP (19.8 ± 0.6 min) and FS (19.0 ± 2.5 min), but was shorter in SS (13.2 ± 4.2 min; P < 0.05). The sinusoidal ventilatory amplitude was minimal (37.4 ± 34.9 ml min(-1) W(-1)) during FS but much larger during SS (189.6 ± 120.4 ml min(-1) W(-1)). The total ventilatory response in SS reached 110 ± 8.0% of the incremental test peak, suggesting ventilatory limitation. Slow components in ventilation during constant work rate and FS exercises were detected in most subjects and contributed appreciably to the total response asymptote. The SS exercise was associated with higher mid-exercise lactate concentrations (5.2 ± 1.7, 7.6 ± 1.7 and 4.5 ± 1.3 mmol l(-1) in FS, SS and CP). Large-amplitude, rapid sinusoidal fluctuation in work rate yields little fluctuation in ventilation despite reaching 120% of the incremental test peak work rate. This high-intensity exercise strategy might be suitable for programmes of rehabilitative exercise training in COPD.

PEEP-ZEEP technique: cardiorespiratory repercussions in mechanically ventilated patients submitted to a coronary artery bypass graft surgery

PubMed Central

2011-01-01

Background The PEEP-ZEEP technique is previously described as a lung inflation through a positive pressure enhancement at the end of expiration (PEEP), followed by rapid lung deflation with an abrupt reduction in the PEEP to 0 cmH2O (ZEEP), associated to a manual bilateral thoracic compression. Aim To analyze PEEP-ZEEP technique's repercussions on the cardio-respiratory system in immediate postoperative artery graft bypass patients. Methods 15 patients submitted to a coronary artery bypass graft surgery (CABG) were enrolled prospectively, before, 10 minutes and 30 minutes after the technique. Patients were curarized, intubated, and mechanically ventilated. To perform PEEP-ZEEP technique, saline solution was instilled into their orotracheal tube than the patient was reconnected to the ventilator. Afterwards, the PEEP was increased to 15 cmH2O throughout 5 ventilatory cycles and than the PEEP was rapidly reduced to 0 cmH2O along with manual bilateral thoracic compression. At the end of the procedure, tracheal suction was accomplished. Results The inspiratory peak and plateau pressures increased during the procedure (p < 0.001) compared with other pressures during the assessment periods; however, they were within lung safe limits. The expiratory flow before the procedure were 33 ± 7.87 L/min, increasing significantly during the procedure to 60 ± 6.54 L/min (p < 0.001), diminishing to 35 ± 8.17 L/min at 10 minutes and to 36 ± 8.48 L/min at 30 minutes. Hemodynamic and oxygenation variables were not altered. Conclusion The PEEP-ZEEP technique seems to be safe, without alterations on hemodynamic variables, produces elevated expiratory flow and seems to be an alternative technique for the removal of bronchial secretions in patients submitted to a CABG. PMID:21914178

Nasal high-flow oxygen therapy improves arterial oxygenation during one-lung ventilation in non-intubated thoracoscopic surgery.

PubMed

Wang, Man-Ling; Hung, Ming-Hui; Chen, Jin-Shing; Hsu, Hsao-Hsun; Cheng, Ya-Jung

2018-05-01

Intraoperative hypoxaemia during one-lung ventilation (OLV) remains a major concern in thoracic surgery. Non-intubated video-assisted thoracic surgery (VATS) involves a greater risk of consequent emergent conversion to endotracheal intubation. Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) has recently been reported to be beneficial for higher oxygen reserves during difficult intubations and for enhancing postoperative recovery after thoracic surgery. However, the effects of THRIVE on oxygenation and carbon dioxide elimination before and during OLV in non-intubated VATS have not been investigated. Between September 2016 and October 2016, 30 patients underwent non-intubated VATS for lung tumour and were maintained with THRIVE at a flow of 20 l/min. These patients were compared with a historical control group comprising 30 patients who were maintained with oxygen masks at an oxygen flow of 10 l/min using a propensity score matching algorithm between September 2015 and July 2016. The preoperative arterial oxygen tension was significantly higher in patients maintained with THRIVE than it was in patients maintained with oxygen masks (mean 416.0 vs 265.9 mmHg, P < 0.01). During OLV, arterial oxygen tension remained significantly higher in the THRIVE group than in the oxygen mask group (mean 207.0 vs 127.8 mmHg, P = 0.01). The arterial carbon dioxide tension was comparable before and during OLV. The results indicated that THRIVE effectively increases the oxygen reserve both during OLV and after anaesthesia. Furthermore, non-intubated VATS is safer if THRIVE with flow adjustment is incorporated into a minimally invasive surgical approach, although carbon dioxide elimination is not facilitated.

Postural variation of pulmonary diffusing capacity as a marker of lung microangiopathy in Indian patients with type 2 diabetes mellitus.

PubMed

Kumar, Avinash; Bade, Geetanjali; Trivedi, Anjali; Jyotsna, Viveka P; Talwar, Anjana

2016-01-01

Diabetes mellitus (DM) is characterized by the presence of chronic hyperglycemia and formation of advanced glycation end products (AGEs). Interaction between AGE and its receptor leads to endothelial damage and microangiopathy. This study was undertaken to investigate the possibility of using a postural variation of diffusing capacity as an early marker of lung microangiopathy and its correlation with the level of adhesion molecules, HbA1c, duration of diabetes, and insulin resistance in type 2 DM (T2DM) patients with and without microangiopathy. Forty patients having T2DM without any microangiopathy (n = 20) as well as with microangiopathy (n = 20), and 22 age and sex matched healthy controls were enrolled in this cross-sectional study. Measurement of lung volumes and capacities were done. DLco was measured in sitting and supine position. Levels of vascular cell adhesion molecule-1 (VCAM-1), E-selectin, fasting glucose, and insulin were estimated in plasma of the patients and compared with controls. Restrictive type of ventilatory change was observed in DM patients. Diffusing capacity (% predicted) in the supine position (P < 0.0001), postural change in DLco (P < 0.0001), and coefficient of diffusion were significantly less in DM patients as compared to controls. Plasma levels of VCAM-1 were significantly higher in DM patients without microangiopathy and negatively correlated (r = -0.4054, P = 0.0094) with Δ DLco in all diabetic subjects. All patients had significantly higher insulin resistance. Lack of postural increase in diffusing capacity in type 2 diabetic patients along with increased VCAM-1 levels could reflect the presence of an early microangiopathy of the small pulmonary vessels.

Cross sectional study on lung function of coke oven workers: a lung function surveillance system from 1978 to 1990

PubMed Central

Wu, J; Kreis, I; Griffiths, D; Darling, C

2002-01-01

Aims: To determine the association between lung function of coke oven workers and exposure to coke oven emissions. Methods: Lung function data and detailed work histories for workers in recovery coke ovens of a steelworks were extracted from a lung function surveillance system. Multiple regressions were employed to determine significant predictors for lung function indices. The first sets of lung function tests for 613 new starters were pooled to assess the selection bias. The last sets of lung function tests for 834 subjects with one or more year of coke oven history were pooled to assess determinants of lung function. Results: Selection bias associated with the recruitment process was not observed among the exposure groups. For subjects with a history of one or more years of coke oven work, each year of working in the most exposed "operation" position was associated with reductions in FEV1 of around 9 ml (p = 0.006, 95% CI: 3 ml to 16 ml) and in FVC of around 12 ml (p = 0.002, 95% CI: 4 ml to 19 ml). Negative effects of smoking on lung function were also observed. Conclusions: Exposure to coke oven emissions was found to be associated with lower FEV1 and FVC. Effects of work exposure on lung function are similar to those found in other studies. PMID:12468747

Ventilatory baroreflex sensitivity in humans is not modulated by chemoreflex activation

PubMed Central

Rivera, Eileen; Clarke, Debbie A.; Baugham, Ila L.; Ocon, Anthony J.; Taneja, Indu; Terilli, Courtney; Medow, Marvin S.

2011-01-01

Increasing arterial blood pressure (AP) decreases ventilation, whereas decreasing AP increases ventilation in experimental animals. To determine whether a “ventilatory baroreflex” exists in humans, we studied 12 healthy subjects aged 18–26 yr. Subjects underwent baroreflex unloading and reloading using intravenous bolus sodium nitroprusside (SNP) followed by phenylephrine (“Oxford maneuver”) during the following “gas conditions:” room air, hypoxia (10% oxygen)-eucapnia, and 30% oxygen-hypercapnia to 55–60 Torr. Mean AP (MAP), heart rate (HR), cardiac output (CO), total peripheral resistance (TPR), expiratory minute ventilation (VE), respiratory rate (RR), and tidal volume were measured. After achieving a stable baseline for gas conditions, we performed the Oxford maneuver. VE increased from 8.8 ± 1.3 l/min in room air to 14.6 ± 0.8 l/min during hypoxia and to 20.1 ± 2.4 l/min during hypercapnia, primarily by increasing tidal volume. VE doubled during SNP. CO increased from 4.9 ± .3 l/min in room air to 6.1 ± .6 l/min during hypoxia and 6.4 ± .4 l/min during hypercapnia with decreased TPR. HR increased for hypoxia and hypercapnia. Sigmoidal ventilatory baroreflex curves of VE versus MAP were prepared for each subject and each gas condition. Averaged curves for a given gas condition were obtained by averaging fits over all subjects. There were no significant differences in the average fitted slopes for different gas conditions, although the operating point varied with gas conditions. We conclude that rapid baroreflex unloading during the Oxford maneuver is a potent ventilatory stimulus in healthy volunteers. Tidal volume is primarily increased. Ventilatory baroreflex sensitivity is unaffected by chemoreflex activation, although the operating point is shifted with hypoxia and hypercapnia. PMID:21317304

Reduction of duration and cost of mechanical ventilation in an intensive care unit by use of a ventilatory management team.

PubMed

Cohen, I L; Bari, N; Strosberg, M A; Weinberg, P F; Wacksman, R M; Millstein, B H; Fein, I A

1991-10-01

To test the hypothesis that a formal interdisciplinary team approach to managing ICU patients requiring mechanical ventilation enhances ICU efficiency. Retrospective review with cost-effectiveness analysis. A 20-bed medical-surgical ICU in a 450-bed community referral teaching hospital with a critical care fellowship training program. All patients requiring mechanical ventilation in the ICU were included, comparing patients admitted 1 yr before the inception of the ventilatory management team (group 1) with those patients admitted for 1 yr after the inception of the team (group 2). Group 1 included 198 patients with 206 episodes of mechanical ventilation and group 2 included 165 patients with 183 episodes of mechanical ventilation. A team consisting of an ICU attending physician, nurse, and respiratory therapist was formed to conduct rounds regularly and supervise the ventilatory management of ICU patients who were referred to the critical care service. The two study groups were demographically comparable. However, there were significant reductions in resource use in group 2. The number of days on mechanical ventilation decreased (3.9 days per episode of mechanical ventilation [95% confidence interval 0.3 to 7.5 days]), as did days in the ICU (3.3 days per episode of mechanical ventilation [90% confidence interval 0.3 to 6.3 days]), numbers of arterial blood gases (23.2 per episode of mechanical ventilation; p less than .001), and number of indwelling arterial catheters (1 per episode of mechanical ventilation; p less than .001). The estimated cost savings from these reductions was $1,303 per episode of mechanical ventilation. We conclude that a ventilatory management team, or some component thereof, can significantly and safely expedite the process of "weaning" patients from mechanical ventilatory support in the ICU.

Model-based stability assessment of ventilatory control in overweight adolescents with obstructive sleep apnea during NREM sleep.

PubMed

Nava-Guerra, L; Tran, W H; Chalacheva, P; Loloyan, S; Joshi, B; Keens, T G; Nayak, K S; Davidson Ward, S L; Khoo, M C K

2016-07-01

Obstructive sleep apnea (OSA) involves the interplay of several different factors such as an unfavorable upper airway anatomy, deficiencies in pharyngeal muscle responsiveness, a low arousal threshold, and ventilatory control instability. Although the stability of ventilatory control has been extensively studied in adults, little is known about its characteristics in the pediatric population. In this study, we developed a novel experimental setup that allowed us to perturb the respiratory system during natural non-rapid eye movement (NREM) sleep conditions by manipulating the inspiratory pressure, provided by a bilevel pressure ventilator, to induce sighs after upper airway stabilization. Furthermore, we present a modeling framework that utilizes the noninvasively measured ventilatory responses to the induced sighs and spontaneous breathing data to obtain representations of the processes involved in the chemical regulation of respiration and extract their stability characteristics. After validation with simulated data, the modeling technique was applied to data collected experimentally from 11 OSA and 15 non-OSA overweight adolescents. Statistical analysis of the model-derived stability parameters revealed a significantly higher plant gain and lower controller gain in the OSA group (P = 0.046 and P = 0.007, respectively); however, no differences were found in loop gain (LG) and circulatory time delay between the groups. OSA severity and LG, within the 0.03-0.04-Hz frequency band, were significantly negatively associated (r = -0.434, P = 0.026). Contrary to what has been found in adults, our results suggest that in overweight adolescents, OSA is unlikely to be initiated through ventilatory instability resulting from elevated chemical loop gain. Copyright © 2016 the American Physiological Society.

Ventilatory responses to dynamic exercise elicited by intramuscular sensors

NASA Technical Reports Server (NTRS)

Smith, S. A.; Gallagher, K. M.; Norton, K. H.; Querry, R. G.; Welch-O'Connor, R. M.; Raven, P. B.

1999-01-01

PURPOSE: Eight subjects, aged 27.0+/-1.6 yr, performed incremental workload cycling to investigate the contribution of skeletal muscle mechano- and metaboreceptors to ventilatory control during dynamic exercise. METHODS: Each subject performed four bouts of exercise: exercise with no intervention (CON); exercise with bilateral thigh cuffs inflated to 90 mm Hg (CUFF); exercise with application of lower-body positive pressure (LBPP) to 45 torr (PP); and exercise with 90 mm Hg thigh cuff inflation and 45 torr LBPP (CUFF+PP). Ventilatory responses and pulmonary gas exchange variables were collected breath-by-breath with concomitant measurement of leg intramuscular pressure. RESULTS: Ventilation (VE) was significantly elevated from CON during PP and CUFF+PP at workloads corresponding to > or = 60% CON peak oxygen uptake (VO2peak) and during CUFF at workloads > or = 80% CON VO2peak, P < 0.05. The VO2 at which ventilatory threshold occurred was significantly reduced from CON (2.17+/-0.28 L x min(-1)) to 1.60+/-0.19 L x min(-1), 1.45+/-0.15 L x min(-1), and 1.15+/-0.11 L x min(-1) during CUFF, PP, and CUFF+PP, respectively. The slope of the linear regression describing the VE/CO2 output relationship was increased from CON by approximately 22% during CUFF, 40% during PP, and 41% during CUFF+PP. CONCLUSIONS: As intramuscular pressure was significantly elevated immediately upon application of LBPP during PP and CUFF+PP without a concomitant increase in VE, it seems unlikely that LBPP-induced increases in VE can be attributed to activation of the mechanoreflex. These findings suggest that LBPP-induced reductions in perfusion pressure and decreases in venous outflow resulting from inflation of bilateral thigh cuffs may generate a metabolite sensitive intramuscular ventilatory stimulus.

Arousal from sleep does not lead to reduced dilator muscle activity or elevated upper airway resistance on return to sleep in healthy individuals.

PubMed

Jordan, Amy S; Cori, Jennifer M; Dawson, Andrew; Nicholas, Christian L; O'Donoghue, Fergal J; Catcheside, Peter G; Eckert, Danny J; McEvoy, R Doug; Trinder, John

2015-01-01

To compare changes in end-tidal CO2, genioglossus muscle activity and upper airway resistance following tone-induced arousal and the return to sleep in healthy individuals with small and large ventilatory responses to arousal. Observational study. Two sleep physiology laboratories. 35 men and 25 women with no medical or sleep disorders. Auditory tones to induce 3-s to 15-s cortical arousals from sleep. During arousal from sleep, subjects with large ventilatory responses to arousal had higher ventilation (by analytical design) and tidal volume, and more marked reductions in the partial pressure of end-tidal CO2 compared to subjects with small ventilatory responses to arousal. However, following the return to sleep, ventilation, genioglossus muscle activity, and upper airway resistance did not differ between high and low ventilatory response groups (Breath 1 on return to sleep: ventilation 6.7±0.4 and 5.5±0.3 L/min, peak genioglossus activity 3.4%±1.0% and 4.8%±1.0% maximum, upper airway resistance 4.7±0.7 and 5.5±1.0 cm H2O/L/s, respectively). Furthermore, dilator muscle activity did not fall below the pre-arousal sleeping level and upper airway resistance did not rise above the pre-arousal sleeping level in either group for 10 breaths following the return to sleep. Regardless of the magnitude of the ventilatory response to arousal from sleep and subsequent reduction in PETCO2, healthy individuals did not develop reduced dilator muscle activity nor increased upper airway resistance, indicative of partial airway collapse, on the return to sleep. These findings challenge the commonly stated notion that arousals predispose to upper airway obstruction. © 2014 Associated Professional Sleep Societies, LLC.

The self-perception of dyspnoea threshold during the 6-min walk test: a good alternative to estimate the ventilatory threshold in chronic obstructive pulmonary disease.

PubMed

Couillard, Annabelle; Tremey, Emilie; Prefaut, Christian; Varray, Alain; Heraud, Nelly

2016-12-01

To determine and/or adjust exercise training intensity for patients when the cardiopulmonary exercise test is not accessible, the determination of dyspnoea threshold (defined as the onset of self-perceived breathing discomfort) during the 6-min walk test (6MWT) could be a good alternative. The aim of this study was to evaluate the feasibility and reproducibility of self-perceived dyspnoea threshold and to determine whether a useful equation to estimate ventilatory threshold from self-perceived dyspnoea threshold could be derived. A total of 82 patients were included and performed two 6MWTs, during which they raised a hand to signal self-perceived dyspnoea threshold. The reproducibility in terms of heart rate (HR) was analysed. On a subsample of patients (n=27), a stepwise regression analysis was carried out to obtain a predictive equation of HR at ventilatory threshold measured during a cardiopulmonary exercise test estimated from HR at self-perceived dyspnoea threshold, age and forced expiratory volume in 1 s. Overall, 80% of patients could identify self-perceived dyspnoea threshold during the 6MWT. Self-perceived dyspnoea threshold was reproducibly expressed in HR (coefficient of variation=2.8%). A stepwise regression analysis enabled estimation of HR at ventilatory threshold from HR at self-perceived dyspnoea threshold, age and forced expiratory volume in 1 s (adjusted r=0.79, r=0.63, and relative standard deviation=9.8 bpm). This study shows that a majority of patients with chronic obstructive pulmonary disease can identify a self-perceived dyspnoea threshold during the 6MWT. This HR at the dyspnoea threshold is highly reproducible and enable estimation of the HR at the ventilatory threshold.

Autonomic, functional, skeletal muscle, and cardiac abnormalities are associated with increased ergoreflex sensitivity in mitochondrial disease.

PubMed

Giannoni, Alberto; Aimo, Alberto; Mancuso, Michelangelo; Piepoli, Massimo Francesco; Orsucci, Daniele; Aquaro, Giovanni Donato; Barison, Andrea; De Marchi, Daniele; Taddei, Claudia; Cameli, Matteo; Raglianti, Valentina; Siciliano, Gabriele; Passino, Claudio; Emdin, Michele

2017-12-01

Mitochondrial disease (MD) is a genetic disorder affecting skeletal muscles, with possible myocardial disease. The ergoreflex, sensitive to skeletal muscle work, regulates ventilatory and autonomic responses to exercise. We hypothesized the presence of an increased ergoreflex sensitivity in MD patients, its association with abnormal ventilatory and autonomic responses, and possibly with subclinical cardiac involvement. Twenty-five MD patients (aged 46 ± 3 years, 32% male) with skeletal myopathy but without known cardiac disease, underwent a thorough evaluation including BNPs, galectin-3, soluble suppression of tumorigenesis 2 (sST2), high sensitivity troponin T/I, catecholamines, ECG, 24-h ECG recording, cardiopulmonary exercise testing, echocardiography, cardiac/muscle magnetic resonance (C/MMR), and ergoreflex assessment. Thirteen age- and sex-matched healthy controls were chosen. Among these myopathic patients, subclinical cardiac damage was detected in up to 80%, with 44% showing fibrosis at CMR. Ergoreflex sensitivity was markedly higher in patients than in controls (64% vs. 37%, P < 0.001), and correlated with muscle fat to water ratio and extracellular volume at MMR (both P < 0.05). Among patients, ergoreflex sensitivity was higher in those with cardiac involvement (P = 0.034). Patients showed a lower peak oxygen consumption (VO 2 /kg) than controls (P < 0.001), as well as ventilatory inefficiency (P = 0.024). Ergoreflex sensitivity correlated with reduced workload and peak VO 2 /kg (both P < 0.001), and several indicators of autonomic imbalance (P < 0.05). Plasma norepinephrine was the unique predictor of myocardial fibrosis at univariate analysis (P < 0.05). Skeletal myopathy in MD is characterized by enhanced ergoreflex sensitivity, which is associated with a higher incidence of cardiac involvement, exercise intolerance, and sympathetic activation. © 2017 The Authors. European Journal of Heart Failure © 2017 European Society of Cardiology.

Ventilatory function assessment in safety pharmacology: Optimization of rodent studies using normocapnic or hypercapnic conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goineau, Sonia; Rompion, Sonia; Guillaume, Philippe

2010-09-15

Although the whole body plethysmography for unrestrained animals is the most widely used method to assess the respiratory risk of new drugs in safety pharmacology, non-appropriate experimental conditions may mask deleterious side effects of some substances. If stimulant or bronchodilatory effects can be easily evidenced in rodents under standard experimental conditions, i.e. normal air breathing and diurnal phase, drug-induced respiratory depression remains more difficult to detect. This study was aimed at comparing the responsiveness of Wistar rats, Duncan Hartley guinea-pigs or BALB/c mice to the respiratory properties of theophylline (50 or 100 mg/kg p.o.) or morphine (30 mg/kg i.p.) undermore » varying conditions (100% air versus 5% CO{sub 2}-enriched air, light versus dark day phase), in order to select the most appropriate experimental conditions to each species for safety airway investigations. Our results showed that under normocapnia the ventilatory depressant effects of morphine can be easily evidenced in mice, slightly observed in guinea-pigs and not detected in rats in any day phase. Slight hypercapnic conditions enhanced the responsiveness of rats to morphine but not that of guinea-pigs and importantly they did not blunt the airway responsiveness of rats to the stimulation and bronchodilation evoked by theophylline, the most widely used reference agent in safety pharmacology studies. In conclusion, hypercapnic conditions associated with the non-invasive whole body plethysmography should be considered for optimizing the assessment of both the ventilatory depressant potential of morphine-like substances or the respiratory stimulant effects of new drugs in the rat, the most extensively used species in rodent safety and toxicological investigations.« less

Complex sleep apnoea in congestive heart failure.

PubMed

Bitter, Thomas; Westerheide, Nina; Hossain, Mohammed Sajid; Lehmann, Roman; Prinz, Christian; Kleemeyer, Astrid; Horstkotte, Dieter; Oldenburg, Olaf

2011-05-01

Sleep disordered breathing is common and of prognostic significance in patients with congestive heart failure (CHF). Complex sleep apnoea (complexSA) is defined as the emergence of central sleep apnoea during continuous positive airway pressure (CPAP) treatment in patients with obstructive sleep apnoea (OSA). This study aims to determine the prevalence and predictors for complexSA in patients with CHF with OSA, and to assess the effects of treatment with adaptive servoventilation. 192 patients with CHF (left ventricular ejection fraction (LVEF) ≤45%, New York Heart Association (NYHA) class ≥2) and OSA (apnoea-hypopnoea index (AHI) ≥15) were investigated using echocardiography, cardiopulmonary exercise testing, measurement of hyperoxic, hypercapnic ventilatory response, 6 min walk test and measurement of N-terminal pro-brain natriuretic peptide (NT-proBNP) prior to CPAP introduction. If patients demonstrated complexSA (AHI >15/h with <10% obstructive events) during CPAP titration, adaptive servoventilation was introduced and the investigations were repeated at 3 monthly follow-up visits. ComplexSA developed in 34 patients (18%) during CPAP titration. After adjustment for demographic and cardiac parameters, measures of CO(2) sensitivity (higher hyperoxic, hypercapnic ventilatory response) were independently associated with complexSA. Patients using adaptive servoventilation had improved AHI, NYHA class, NT-proBNP concentration, LVEF, hyperoxic, hypercapnic ventilatory response, oxygen uptake during cardiopulmonary exercise testing and the relationship between minute ventilation and the rate of CO(2) elimination (VE/Vco(2) slope) at last individual follow-up (14±4 months). There is a high prevalence of complexSA in patients with OSA and CHF, and those who develop complexSA have evidence of higher respiratory controller gain before application of CPAP. Treatment with adaptive servoventilation effectively suppressed complexSA and had positive effects on cardiac function and respiratory stability.

Asfotase Alfa Treatment Improves Survival for Perinatal and Infantile Hypophosphatasia

PubMed Central

Rockman-Greenberg, Cheryl; Ozono, Keiichi; Riese, Richard; Moseley, Scott; Melian, Agustin; Thompson, David D.; Bishop, Nicholas; Hofmann, Christine

2016-01-01

Context: Hypophosphatasia (HPP) is an inborn error of metabolism that, in its most severe perinatal and infantile forms, results in 50–100% mortality, typically from respiratory complications. Objectives: Our objective was to better understand the effect of treatment with asfotase alfa, a first-in-class enzyme replacement therapy, on mortality in neonates and infants with severe HPP. Design/Setting: Data from patients with the perinatal and infantile forms of HPP in two ongoing, multicenter, multinational, open-label, phase 2 interventional studies of asfotase alfa treatment were compared with data from similar patients from a retrospective natural history study. Patients: Thirty-seven treated patients (median treatment duration, 2.7 years) and 48 historical controls of similar chronological age and HPP characteristics. Interventions: Treated patients received asfotase alfa as sc injections either 1 mg/kg six times per week or 2 mg/kg thrice weekly. Main Outcome Measures: Survival, skeletal health quantified radiographically on treatment, and ventilatory status were the main outcome measures for this study. Results: Asfotase alfa was associated with improved survival in treated patients vs historical controls: 95% vs 42% at age 1 year and 84% vs 27% at age 5 years, respectively (P < .0001, Kaplan-Meier log-rank test). Whereas 5% (1/20) of the historical controls who required ventilatory assistance survived, 76% (16/21) of the ventilated and treated patients survived, among whom 75% (12/16) were weaned from ventilatory support. This better respiratory outcome accompanied radiographic improvements in skeletal mineralization and health. Conclusions: Asfotase alfa mineralizes the HPP skeleton, including the ribs, and improves respiratory function and survival in life-threatening perinatal and infantile HPP. PMID:26529632

Respiratory response to toluene diisocyanate depends on prior frequency and concentration of dermal sensitization in mice.

PubMed

Vanoirbeek, Jeroen A J; Tarkowski, Maciej; Ceuppens, Jan L; Verbeken, Erik K; Nemery, Benoit; Hoet, Peter H M

2004-08-01

Occupational asthma is the principal cause of work-related respiratory disease in the industrial world. In the absence of satisfactory models for predicting the potential of low molecular weight chemicals to cause asthma, we verified that dermal sensitization prior to intranasal challenge influences the respiratory response using toluene diisocyanate (TDI), a known respiratory sensitizer. BALB/c mice received TDI or vehicle (acetone/olive oil) on each ear on three consecutive days (days 1, 2, and 3; 0.3 or 3% TDI) or only once (day 1, 1% TDI). On day 7, the mice received similar dermal applications of vehicle or the same concentration of TDI as before ("boost"). On day 10, they received an intranasal dose of TDI (0.1%) or vehicle. Ventilatory function was monitored by whole body plethysmography for 40 min after intranasal application, and reactivity to inhaled methacholine was assessed 24 h later. Pulmonary inflammation was assessed by bronchoalveolar lavage and histology. Mice that received an intranasal dose of TDI without having received a prior dermal application of TDI did not exhibit any ventilatory response or inflammatory changes compared to vehicle controls. In contrast, mice that had received prior application(s) of TDI, even if only on day 7, exhibited the following: ventilatory responses, compatible with bronchoconstriction, immediately after intranasal application with TDI; enhanced methacholine responsiveness 24 h later; and pulmonary inflammation characterized by neutrophils. This was, however, not the case in mice that received the highest dermal amount of TDI (3% on days 1, 2, and 3). These findings suggest that respiratory response to TDI depends on prior frequency and concentration of dermal sensitization in mice.

Health status of Seventh-Day Adventists.

PubMed

Webster, I W; Rawson, G K

1979-05-19

A comparison of health status between 779 Seventh-day Adventists, who have a strong commitment to heal-related life styles, and two other groups of people--8363 persons referred by general practitioners and 9825 volunteers--was made. The Seventh-day Adventists showed less impairment of systolic and diastolic blood pressures, of plasma cholesterol and plasma urate concentrations, and of lung ventilatory capacity; and less obesity at most specific ages. With increasing age, the level of breathlessness, reported heart disease, hypertension, and hypertensive and diuretic therapy in this sample approached that of the comparative groups, possibly because of natural attrition of high-risk persons in the latter. Depression, sleeplessness, use of sedatives and tranquillizers were lower in the Seventh-day Adventists; although, once again, a drawing together of the three groups in older age categories was evident. It is concluded that the life style of Seventh-day Adventists is conducive to lessened morbidity, delayed mortality, and decreased call on health services in comparison with the general population.

The effect of changing the sequence of cuff inflation and device fixation with the LMA-Supreme® on device position, ventilatory complications, and airway morbidity: a clinical and fiberscopic study.

PubMed

Bergmann, Ingo; Crozier, Thomas Allen; Roessler, Markus; Schotola, Hanna; Mansur, Ashham; Büttner, Benedikt; Hinz, José Maria; Bauer, Martin

2014-01-04

The conventional sequence when using supraglottic airway devices is insertion, cuff inflation and fixation. Our hypothesis was that a tighter fit of the cuff and tip could be achieved with a consequently lower incidence of air leak, better separation of gastrointestinal and respiratory tracts and less airway morbidity if the device were first affixed and the cuff then inflated. Our clinical review board approved the study (public registry number DRKS00003174). An LMA Supreme® was inserted into 184 patients undergoing lower limb arthroscopy in propofol-remifentanil anaesthesia who were randomly assigned to either the control (inflation then fixation; n = 92) or study group (fixation then inflation; n = 92). The cuff was inflated to 60 cmH2O. The patients' lungs were ventilated in pressure-controlled mode with 5 cmH2O PEEP, Pmax to give 6 ml kg-1 tidal volume, and respiratory rate adjusted to end-tidal CO2 of 4.8 and 5.6 kPa. Correct cuff and tip position were determined by leak detection, capnometry trace, oropharyngeal leak pressure, suprasternal notch test, and lube-tube test. Bowl and cuff position and the presence of glottic narrowing were assessed by fiberscopic examination. Postoperative dysphagia, hoarseness and sore throat were assessed with a questionnaire. Ventilatory impairment was defined as a tidal volume < 6 ml kg-1 with Pmax at oropharyngeal leak pressure, glottic narrowing was defined as an angle between the vocal cords under 16 degrees. The incidence of incorrect device position (18% vs. 21%), failed ventilation (10% vs. 9%), leak pressure (24.8 vs. 25.2 cmH2O, p = 0.63), failed lube-tube test (16.3% vs. 17.6%) and glottic narrowing (19.3% vs. 14.1%, p = 0.35) was similar in both groups (control vs. study, resp.). When glottic narrowing occurred, it was more frequently associated with ventilatory impairment in the control group (77% vs. 39%; p = 0.04). Airway morbidity was more common in the control group (33% vs. 19%; p < 0.05). Altering the sequence of cuff inflation and device fixation does not affect device position, oropharyngeal leak pressures or separation of gastrointestinal and respiratory tracts. It reduces the incidence of glottic narrowing with impaired ventilation and also perioperative airway morbidity.

TIPSS Procedure in the Treatment of a Single Patient After Recent Heart Transplantation Because of Refractory Ascites Due to Cardiac Cirrhosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fava, Mario; Meneses, Luis, E-mail: lmeneseq@gmail.com; Loyola, Soledad

2008-07-15

We present the case of a female patient with arrhythmogenic dysplasia of the right ventricle who evolved to refractory heart failure, ascites, and peripheral edema. As a result, heart transplantation was performed. Subsequently, refractory ascites impaired the patient's respiratory function, resulting in prolonged mechanical ventilation. She was successfully treated with transjugular intrahepatic portosystemic shunt (TIPSS) placement, which allowed satisfactory weaning of ventilatory support.

Zinc toxicity among galvanization workers in the iron and steel industry.

PubMed

El Safty, Amal; El Mahgoub, Khalid; Helal, Sawsan; Abdel Maksoud, Neveen

2008-10-01

Galvanization is the process of coating steel or cast iron pieces with zinc, allowing complete protection against corrosion. The ultimate goal of this work was to assess the effect of occupational exposure to zinc in the galvanization process on different metals in the human body and to detect the association between zinc exposure and its effect on the respiratory system. This study was conducted in 111 subjects in one of the major companies in the iron and steel industry. There were 61 subjects (workers) who were involved in the galvanization process. Fifty adult men were chosen as a matched reference group from other departments of the company. All workers were interviewed using a special questionnaire on occupational history and chest diseases. Ventilatory functions and chest X rays were assessed in all examined workers. Also, complete blood counts were performed, and serum zinc, iron, copper, calcium, and magnesium levels were tested. This study illustrated the relation between zinc exposure in the galvanization process and high zinc levels among exposed workers, which was associated with a high prevalence rate of metal fume fever (MFF) and low blood copper and calcium levels. There was no statistically significant difference between the exposed and control groups with regards to the magnesium level. No long-term effect of metals exposure was detected on ventilatory functions or chest X rays among the exposed workers.

Running economy and body composition between competitive and recreational level distance runners.

PubMed

Mooses, Martin; Jürimäe, J; Mäestu, J; Mooses, K; Purge, P; Jürimäe, T

2013-09-01

The aim of the present study was to compare running economy between competitive and recreational level athletes at their individual ventilatory thresholds on track and to compare body composition parameters that are related to the individual running economy measured on track. We performed a cross-sectional analysis of a total 45 male runners classified as competitive runners (CR; n = 28) and recreational runners (RR; n = 17). All runners performed an incremental test on treadmill until voluntary exhaustion and at least 48 h later a 2 × 2000 m test at indoor track with intensities according to ventilatory threshold 1, ventilator threshold 2. During the running tests, athletes wore portable oxygen analyzer. Body composition was measured with Dual energy X-ray absorptiometry (DXA) method. Running economy at the first ventilatory threshold was not significantly related to any of the measured body composition values or leg mass ratios either in the competitive or in the recreational runners group. This study showed that there was no difference in the running economy between distance runners with different performance level when running on track, while there was a difference in the second ventilatory threshold speed in different groups of distance runners. Differences in running economy between competitive and recreational athletes cannot be explained by body composition and/or different leg mass ratios.

Predictive value of ventilatory inflection points determined under field conditions.

PubMed

Heyde, Christian; Mahler, Hubert; Roecker, Kai; Gollhofer, Albert

2016-01-01

The aim of this study was to evaluate the predictive potential provided by two ventilatory inflection points (VIP1 and VIP2) examined in field without using gas analysis systems and uncomfortable facemasks. A calibrated respiratory inductance plethysmograph (RIP) and a computerised routine were utilised, respectively, to derive ventilation and to detect VIP1 and VIP2 during a standardised field ramp test on a 400 m running track on 81 participants. In addition, average running speed of a competitive 1000 m run (S1k) was observed as criterion. The predictive value of running speed at VIP1 (SVIP1) and the speed range between VIP1 and VIP2 in relation to VIP2 (VIPSPAN) was analysed via regression analysis. VIPSPAN rather than running speed at VIP2 (SVIP2) was operationalised as a predictor to consider the covariance between SVIP1 and SVIP2. SVIP1 and VIPSPAN, respectively, provided 58.9% and 22.9% of explained variance in regard to S1k. Considering covariance, the timing of two ventilatory inflection points provides predictive value in regard to a competitive 1000 m run. This is the first study to apply computerised detection of ventilatory inflection points in a field setting independent on measurements of the respiratory gas exchange and without using any facemasks.

Time Domains of the Hypoxic Ventilatory Response and Their Molecular Basis

PubMed Central

Pamenter, Matthew E.; Powell, Frank L.

2016-01-01

Ventilatory responses to hypoxia vary widely depending on the pattern and length of hypoxic exposure. Acute, prolonged, or intermittent hypoxic episodes can increase or decrease breathing for seconds to years, both during the hypoxic stimulus, and also after its removal. These myriad effects are the result of a complicated web of molecular interactions that underlie plasticity in the respiratory control reflex circuits and ultimately control the physiology of breathing in hypoxia. Since the time domains of the physiological hypoxic ventilatory response (HVR) were identified, considerable research effort has gone toward elucidating the underlying molecular mechanisms that mediate these varied responses. This research has begun to describe complicated and plastic interactions in the relay circuits between the peripheral chemoreceptors and the ventilatory control circuits within the central nervous system. Intriguingly, many of these molecular pathways seem to share key components between the different time domains, suggesting that varied physiological HVRs are the result of specific modifications to overlapping pathways. This review highlights what has been discovered regarding the cell and molecular level control of the time domains of the HVR, and highlights key areas where further research is required. Understanding the molecular control of ventilation in hypoxia has important implications for basic physiology and is emerging as an important component of several clinical fields. PMID:27347896

Behavioral and autonomic thermoregulation in hamsters during microwave-induced heat exposure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gordon, C.J.; Long, M.D.; Fehlner, K.S.

1984-01-01

Preferred ambient temperature (Ta) and ventilatory frequency were measured in free-moving hamsters exposed to 2450-MHz microwaves. A waveguide exposure system that permits continuous monitoring of the absorbed heat load accrued from microwave exposure was imposed with a longitudinal temperature gradient which allowed hamsters to select their preferred Ta. Ventilatory frequency was monitored remotely by analysing the rhythmic shifts in unabsorbed microwave energy passing down the waveguide. Without microwave exposure hamsters selected an average T2 of 30.2 C. This preferred Ta did not change until the rate of heat absorption (SAR) from microwave exposure exceeded approx. 2 W kg-1. In amore » separate experiment, a SAR of 2.0 W kg-1 at a Ta of 30C was shown to promote an average 0.5 C increase in colonic temperature. Hamsters maintained their ventilatory frequency at baseline levels by selecting a cooler Ta during microwave exposure. These data support previous studies suggesting that during thermal stress behavioral thermo-regulation (i.e. preferred Ta) takes prescedence over autonomic thermoregulation (i.e. ventilatory frequency). It is apparent that selecting a cooler Ta is a more efficient and/or effective than autonomic thermoregulation for dissipating a heat load accrued from microwave exposure.« less

Pulmonary manifestations of ankylosing spondylitis.

PubMed

Kanathur, Naveen; Lee-Chiong, Teofilo

2010-09-01

Ankylosing spondylitis, a chronic multisystem inflammatory disorder, can present with articular and extra-articular features. It can affect the tracheobronchial tree and the lung parenchyma, and respiratory complications include chest wall restriction, apical fibrobullous disease with or without secondary pulmonary superinfection, spontaneous pneumothorax, and obstructive sleep apnea. Ankylosing spondylitis is a common cause of pulmonary apical fibrocystic disease; early involvement may be unilateral or asymmetrical, but most cases eventually consist of bilateral apical fibrobullous lesions, many of which are progressive with coalescence of the nodules, formation of cysts and cavities, fibrosis, and bronchiectasis. Mycobacterial or fungal superinfection of the upper lobe cysts and cavities occurs commonly. Aspergillus fumigatus is the most common pathogen isolated, followed by various species of mycobacteria. Prognosis of patients with fibrobullous apical lesions is mainly determined by the presence, extent, and severity of superinfection. Pulmonary function test results are nonspecific and generally parallel the severity of parenchymal involvement. A restrictive ventilatory impairment can develop in patients with ankylosing spondylitis because of either fusion of the costovertebral joints and ankylosis of the thoracic spine or anterior chest wall involvement. Chest radiographic findings may mirror the severity of clinical involvement. Pulmonary parenchymal disease is typically progressive, and cyst formation, cavitation, and fibrosis are seen in advanced cases. No treatment has been shown to alter the clinical course of apical fibrobullous disease. Although several antiinflammatory agents, such as infliximab, etanercept, and adalimumab, are being used to treat ankylosing spondylitis, their effects on pulmonary manifestations are unclear.

CO diffusing capacity in a general population sample: relationships with cigarette smoking and airflow obstruction.

PubMed

Viegi, G; Paoletti, P; Carrozzi, L; Baldacci, S; Modena, P; Pedreschi, M; Di Pede, F; Mammini, U; Giuntini, C

1993-01-01

The single-breath carbon monoxide diffusing capacity (DLCOsb) was measured together with ventilatory lung function tests as part of a survey of a general population sample living in Northern Italy (n = 2,481). Based on answers to an interviewer-administered questionnaire, subjects free of respiratory symptoms or diseases were identified. Data from subjects who had never regularly smoked cigarettes were used to derive reference equations for the test indexes, and data from the remaining subjects who had smoked were used to derive regression equations incorporating a term expressing cigarette consumption (cube root of pack-years) and a term indicating current smoking decrement, in order to obtain expected DLCOsb percent predicted. Neither number of cigarettes smoked daily or duration of smoking, in smokers, nor duration of smoking or years since quitting smoking, in ex-smokers, entered significantly the multiple-regression model. The mean values of DLCOsb were only slightly affected by the increasing degree of airway obstruction. When subjects with confirmed asthma were analyzed, after stratifying for different levels of FEV1/FVC ratio, increased mean value of DLCOsb (over 100%) was found in those with an FEV1/FVC ratio between 75 and 65%. This cross-sectional analysis suggests that there is a decrease in DLCOsb with cumulative cigarette consumption even in healthy subjects. Further, it confirms the clinical observations of high DLCOsb values in asthmatic patients, at least in those with an initial degree of chronic airflow obstruction.

Cardiorespiratory interactions during periodic breathing in awake chronic heart failure patients.

PubMed

Pinna, G D; Maestri, R; Mortara, A; La Rovere, M T

2000-03-01

We applied spectral techniques to the analysis of cardiorespiratory signals [instantaneous lung volume (ILV), instantaneous tidal volume (ITV), arterial O(2) saturation (Sa(O(2))) at the ear, heart rate (HR), systolic (SAP), and diastolic (DAP) arterial pressure] during nonapneic periodic breathing (PB) in 29 awake chronic heart failure (CHF) patients and estimated the timing relationships between respiratory and slow cardiovascular (<0.04 Hz) oscillations. Our aim was 1) to elucidate major mechanisms involved in cardiorespiratory interactions during PB and 2) to test the hypothesis of a central vasomotor origin of PB. All cardiovascular signals were characterized by a dominant (>/=84% of total power) oscillation at the frequency of PB (mean +/- SE: 0.022 +/- 0.0008 Hz), highly coherent (>/=0.89), and delayed with respect to ITV (ITV-HR, 2.4 +/- 0.72 s; ITV-SAP, 6.7 +/- 0.65 s; ITV-DAP, 3.2 +/- 0.61 s; P < 0.01). Sa(O(2)) was highly coherent with (coherence function = 0.96 +/- 0. 009) and almost opposite in phase to ITV. These findings demonstrate the existence of a generalized cardiorespiratory rhythm led by the ventilatory oscillation and suggest that 1) the cyclic increase in inspiratory drive and cardiopulmonary reflexes and 2) mechanical effects of PB-induced changes in intrathoracic pressure are the more likely sources of the HR and blood pressure oscillations, respectively. The timing relationship between ITV and blood pressure signals excludes the possibility that PB represents the effect of a central vasomotor rhythm.

Age-related differences in pulmonary effects of acute and ...

EPA Pesticide Factsheets

Ozone (O3) is known to induce adverse pulmonary and systemic health effects. Importantly, children and older persons are considered at-risk populations for O3-induced dysfunction, yet the mechanisms accounting for the age-related pulmonary responses to O3 are uncertain. In this study, we examined age-related susceptibility to O3 using 1 mo (adolescent), 4 mo (young adult), 12 mo (adult) and 24 mo (senescent) male Brown Norway rats exposed to filtered air or O3 (0.25and 1.00 ppm), 6 h/day, two days/week for 1 week (acute) or 13 weeks (subchronic). Ventilatory function, assessed by whole-body plethysmography, and bronchoalveolar lavage fluid (BALF) biomarkers of injury and inflammation were used to examine O3-induced pulmonary effects.Relaxation time declined in all ages following the weekly exposures; however, this effect persisted only in the 24 mo rats following a five days recovery, demonstrating an inability to induce adaptation commonly seen with repeated O3 exposures. PenH was increased in all groups with an augmented response in the 4 mo rats following the subchronic O3 exposures. O3 led to increased breathing frequency and minute volume in the 1 and 4 mo animals. Markers ofpulmonary permeability were increased in all age groups. Elevations in BALF γ-glutamyl transferase activity and lung inflammation following an acute O3 exposure were noted in only the 1 and 4 mo rats, which likely received an increased effective O3 dose. These data demonstrate that ado

Pleural plaques and their effect on lung function in Libby vermiculite miners.

PubMed

Clark, Kathleen A; Flynn, J Jay; Goodman, Julie E; Zu, Ke; Karmaus, Wilfried J J; Mohr, Lawrence C

2014-09-01

Multiple studies have investigated the relationship between asbestos-related pleural plaques (PPs) and lung function, with disparate and inconsistent results. Most use chest radiographs to identify PPs and simple spirometry to measure lung function. High-resolution CT (HRCT) scanning improves the accuracy of PP identification. Complete pulmonary function tests (PFTs), including spirometry, lung volumes, and diffusing capacity of the lung for carbon monoxide, provide a more definitive assessment of lung function. The goal of this study was to determine, using HRCT scanning and complete PFTs, the effect of PPs on lung function in Libby vermiculite miners. The results of HRCT scanning and complete PFTs performed between January 2000 and August 2012 were obtained from the medical records of 166 Libby vermiculite miners. Multivariate regression analyses with Tukey multivariate adjustment were used to assess statistical associations between the presence of PPs and lung function. Adjustments were made for age, BMI, smoking history, duration of employment, and years since last occupational asbestos exposure. Nearly 90% of miners (n = 149) had evidence of PPs on HRCT scan. No significant differences in spirometry results, lung volumes, or diffusing capacity of the lung for carbon monoxide were found between miners with PPs alone and miners with normal HRCT scans. Miners with both interstitial fibrosis and the presence of PPs had a significantly decreased total lung capacity in comparison with miners with normal HRCT scans (P = .02). Age, cumulative smoking history, and BMI were significant covariates that contributed to abnormal lung function. Asbestos-related PPs alone have no significant effect on lung function in Libby vermiculite miners.

Fibroblast growth factor 10 haploinsufficiency causes chronic obstructive pulmonary disease.

PubMed

Klar, Joakim; Blomstrand, Peter; Brunmark, Charlott; Badhai, Jitendra; Håkansson, Hanna Falk; Brange, Charlotte Sollie; Bergendal, Birgitta; Dahl, Niklas

2011-10-01

Genetic factors influencing lung function may predispose to chronic obstructive pulmonary disease (COPD). The fibroblast growth factor 10 (FGF10) signalling pathway is critical for lung development and lung epithelial renewal. The hypothesis behind this study was that constitutive FGF10 insufficiency may lead to pulmonary disorder. Therefore investigation of the pulmonary functions of patients heterozygous for loss of function mutations in the FGF10 gene was performed. The spirometric measures of lung function from patients and non-carrier siblings were compared and both groups were related to matched reference data for normal human lung function. The patients show a significant decrease in lung function parameters when compared to control values. The average FEV1/IVC quota (FEV1%) for the patients is 0.65 (80% of predicted) and reversibility test using Terbutalin resulted in a 3.7% increase in FEV1. Patients with FGF10 haploinsufficiency have lung function parameters indicating COPD. A modest response to Terbutalin confirms an irreversible obstructive lung disease. These findings support the idea that genetic variants affecting the FGF10 signalling pathway are important determinants of lung function that may ultimately contribute to COPD. Specifically, the results show that FGF10 haploinsufficiency affects lung function measures providing a model for a dosage sensitive effect of FGF10 in the development of COPD.

Control of cardiorespiratory function in response to hypoxia in an air-breathing fish, the African sharptooth catfish, Clarias gariepinus.

PubMed

Belão, T C; Zeraik, V M; Florindo, L H; Kalinin, A L; Leite, C A C; Rantin, F T

2015-09-01

We evaluated the role of the first pair of gill arches in the control of cardiorespiratory responses to normoxia and hypoxia in the air-breathing catfish, Clarias gariepinus. An intact group (IG) and an experimental group (EG, bilateral excision of first gill arch) were submitted to graded hypoxia, with and without access to air. The first pair of gill arches ablations reduced respiratory surface area and removed innervation by cranial nerve IX. In graded hypoxia without access to air, both groups displayed bradycardia and increased ventilatory stroke volume (VT), and the IG showed a significant increase in breathing frequency (fR). The EG exhibited very high fR in normoxia that did not increase further in hypoxia, this was linked to reduced O2 extraction from the ventilatory current (EO2) and a significantly higher critical O2 tension (PcO2) than the IG. In hypoxia with access to air, only the IG showed increased air-breathing, indicating that the first pair of gill arches excision severely attenuated air-breathing responses. Both groups exhibited bradycardia before and tachycardia after air-breaths. The fH and gill ventilation amplitude (VAMP) in the EG were overall higher than the IG. External and internal NaCN injections revealed that O2 chemoreceptors mediating ventilatory hypoxic responses (fR and VT) are internally oriented. The NaCN injections indicated that fR responses were mediated by receptors predominantly in the first pair of gill arches but VT responses by receptors on all gill arches. Receptors eliciting cardiac responses were both internally and externally oriented and distributed on all gill arches or extra-branchially. Air-breathing responses were predominantly mediated by receptors in the first pair of gill arches. In conclusion, the role of the first pair of gill arches is related to: (a) an elevated EO2 providing an adequate O2 uptake to maintain the aerobic metabolism during normoxia; (b) a significant bradycardia and increased fAB elicited by externally oriented O2 chemoreceptors; (c) increase in the ventilatory variables (fR and VAMP) stimulated by internally oriented O2 chemoreceptors. Copyright © 2015 Elsevier Inc. All rights reserved.

A prospective study of the impact of diabetes mellitus on restrictive and obstructive lung function impairment: The Saku study.

PubMed

Sonoda, Nao; Morimoto, Akiko; Tatsumi, Yukako; Asayama, Kei; Ohkubo, Takayoshi; Izawa, Satoshi; Ohno, Yuko

2018-05-01

To assess the impact of diabetes on restrictive and obstructive lung function impairment. This 5-year prospective study included 7524 participants aged 40-69years without lung function impairment at baseline who underwent a comprehensive medical check-up between April 2008 and March 2009 at Saku Central Hospital. Diabetes was defined by fasting plasma glucose ≥7.0mmol/l (126mg/dl), HbA1c≥6.5% (48mmol/mol), or a history of diabetes, as determined by interviews conducted by the physicians. Restrictive and obstructive lung function impairment were defined as forced vital capacity (FVC) <80% predicted and forced expiratory volume in 1s (FEV 1 ) to FVC ratio (FEV 1 /FVC) <0.70, respectively. Participants were screened until they developed restrictive or obstructive lung function impairment or until March 2014. During the follow-up period, 171 and 639 individuals developed restrictive and obstructive lung function impairment, respectively. Individuals with diabetes had a 1.6-fold higher risk of restrictive lung function impairment than those without diabetes after adjusting for sex, age, height, abdominal obesity, smoking status, exercise habits, systolic blood pressure, HDL-cholesterol, log-transformed high-sensitivity C-reactive protein, and baseline lung function [multivariable-adjusted HR and 95% CI; 1.57 (1.04-2.36)]. In contrast, individuals with diabetes did not have a significantly higher risk of obstructive lung function impairment [multivariable-adjusted HR and 95% CI; 0.93 (0.72-1.21)]. Diabetes was associated with restrictive lung function impairment but not obstructive lung function impairment. Copyright © 2017. Published by Elsevier Inc.

Proteasome function is not impaired in healthy aging of the lung.

PubMed

Caniard, Anne; Ballweg, Korbinian; Lukas, Christina; Yildirim, Ali Ö; Eickelberg, Oliver; Meiners, Silke

2015-10-01

Aging is the progressive loss of cellular function which inevitably leads to death. Failure of proteostasis including the decrease in proteasome function is one hallmark of aging. In the lung, proteasome activity was shown to be impaired in age-related diseases such as chronic obstructive pulmonary disease. However, little is known on proteasome function during healthy aging. Here, we comprehensively analyzed healthy lung aging and proteasome function in wildtype, proteasome reporter and immunoproteasome knockout mice. Wildtype mice spontaneously developed senile lung emphysema while expression and activity of proteasome complexes and turnover of ubiquitinated substrates was not grossly altered in lungs of aged mice. Immunoproteasome subunits were specifically upregulated in the aged lung and the caspase-like proteasome activity concomitantly decreased. Aged knockout mice for the LMP2 or LMP7 immunoproteasome subunits showed no alteration in proteasome activities but exhibited typical lung aging phenotypes suggesting that immunoproteasome function is dispensable for physiological lung aging in mice. Our results indicate that healthy aging of the lung does not involve impairment of proteasome function. Apparently, the reserve capacity of the proteostasis systems in the lung is sufficient to avoid severe proteostasis imbalance during healthy aging.

Development of a Female Atlas of Strengths

DTIC Science & Technology

1982-02-01

the maximum in water at 2%. The post- exercise hyperaemic response was greater for a given duration of contraction in water at 34 and 42% than at lower...references. 226 STUDY: Duncan, G., Lambie, D.G. and Johnson, R.H. Ventilatory responses to sustained static forearm exercise in man. New Zealand Med. Journal...1978, 88(618), 169. KEYWORDS: Static exercise , ventilatory responses . METHODS: Five healthy subjects were used to study the stimulus for

Effect of Six Days of Staging on Physiologic Adjustments and Acute Mountain Sickness During Ascent to 4300 Meters

DTIC Science & Technology

2009-01-01

respiratory alkalosis due to hyperventilation that was partially compensated for by increased excretion of HCO3 to maintain a normal pH following...carbon dioxide; RER, respiratory exchange quotient; Sao2, arterial oxygen saturation; Paco2, partial pressure of capillary-arterialized carbon dioxide...dioxide production; E=O2, ventilatory equivalent for oxygen; E=CO2, ventilatory equivalent for carbon dioxide; RER, respiratory exchange quotient

Evaluation of chronic bronchitis, chronic obstructive pulmonary disease, and ventilatory function among workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calvert, G.M.; Sweeney, M.H.; Morris, J.A.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is produced as an undesirable contaminant in the manufacture of 2,4,5-trichlorophenol (TCP) and its derivatives. There is considerable concern about the health effects that may be associated with exposure to TCDD-contaminated substances. A cross-sectional medical study that included a comprehensive medical history, medical examination, and measurement of pulmonary function was conducted on workers employed more than 15 yr earlier in the manufacture of NaTCP and its derivatives at two chemical plants. The workers had substantial exposure to substances contaminated with TCDD, as evidenced by a mean serum TCDD level, lipid adjusted, of 200 ppt compared with a meanmore » of 7 ppt in the unexposed reference group. The comparison group consisted of individuals with no occupational exposure to phenoxy herbicides who lived in the same communities as the workers. A total of 281 workers and 260 unexposed referents participated in the medical examination. Logistic and linear regression analyses, which contained categorical and continuous measures of TCDD exposure, were performed to control for important confounders, including cigarette and alcohol consumption. No difference was found between workers and referents in the risk for chronic bronchitis or COPD. Analysis of the ventilatory function data revealed no association between history of exposure to substances contaminated with TCDD and the forced expiratory volume at one second (FEV1), forced vital capacity (FVC), or the ratio of FEV1 to FVC (FEV1/FVC%).« less

Role of vagal afferents in the ventilatory response to naloxone during loaded breathing in the rabbit.

PubMed

Delpierre, S; Pugnat, C; Duté, N; Jammes, Y

1995-02-15

It was previously shown that inspiratory resistive loading (IRL) increases the cerebrospinal fluid (CSF) level of beta endorphin in awake goats, and also that the slower ventilation induced by injection of this substance into the CSF of anesthetized dogs is suppressed after vagotomy. In the present study, performed on anesthetized rabbits, we evaluated the part played by vagal afferents in the ventilatory response to IRL after opioid receptor blockade by naloxone. During unloaded breathing, naloxone injection did not modify baseline ventilation. Conversely, naloxone partially reversed IRL-induced hypoventilation through an increase in respiratory rate. This effect was abolished after either vagotomy or cold blockade of large vagal fibers, but it persisted after procaine blockade of thin vagal fibers. These results suggest that pulmonary stretch receptors, which are connected to some large vagal afferent fibers, would play a major role in the ventilatory response to IRL under opioid receptor inhibition.

Ex Vivo Adenoviral Vector Gene Delivery Results in Decreased Vector-associated Inflammation Pre- and Post–lung Transplantation in the Pig

PubMed Central

Yeung, Jonathan C; Wagnetz, Dirk; Cypel, Marcelo; Rubacha, Matthew; Koike, Terumoto; Chun, Yi-Min; Hu, Jim; Waddell, Thomas K; Hwang, David M; Liu, Mingyao; Keshavjee, Shaf

2012-01-01

Acellular normothermic ex vivo lung perfusion (EVLP) is a novel method of donor lung preservation for transplantation. As cellular metabolism is preserved during perfusion, it represents a potential platform for effective gene transduction in donor lungs. We hypothesized that vector-associated inflammation would be reduced during ex vivo delivery due to isolation from the host immune system response. We compared ex vivo with in vivo intratracheal delivery of an E1-, E3-deleted adenoviral vector encoding either green fluorescent protein (GFP) or interleukin-10 (IL-10) to porcine lungs. Twelve hours after delivery, the lung was transplanted and the post-transplant function assessed. We identified significant transgene expression by 12 hours in both in vivo and ex vivo delivered groups. Lung function remained excellent in all ex vivo groups after viral vector delivery; however, as expected, lung function decreased in the in vivo delivered adenovirus vector encoding GFP (AdGFP) group with corresponding increases in IL-1β levels. Transplanted lung function was excellent in the ex vivo transduced lungs and inferior lung function was seen in the in vivo group after transplantation. In summary, ex vivo delivery of adenoviral gene therapy to the donor lung is superior to in vivo delivery in that it leads to less vector-associated inflammation and provides superior post-transplant lung function. PMID:22453765

[Clinical laboratory tests supporting respiratory disease treatment--chairman's introductory remarks].

PubMed

Takai, Daiya

2014-12-01

The symposium consisted of four parts: history of lung function tests, nitric oxide for diagnosis and monitoring of bronchial asthma, radiological and functional changes of the lung in COPD, and combined pulmonary fibrosis and emphysema (CPFE) occasionally showing almost normal results in lung function tests. The history of lung function tests was presented by Dr. Naoko Tojo of the Tokyo Medical and Dental University. Nitric oxide tests in clinical use for diagnosis and monitoring of bronchial asthma were presented by Dr. Hiroyuki Nagase of Teikyo University. Radiological and functional changes of the lung in COPD were presented by Dr. Shigeo Muro of Kyoto University. Clinical features of combined pulmonary fibrosis and emphysema and their associated lung function were presented by Dr. Daiya Takai of the University of Tokyo. I hope that discussing the history of lung function tests until the present was useful for many medical technologists. (Review).

Acute right heart failure after hemorrhagic shock and trauma pneumonectomy-a management approach: A blinded randomized controlled animal trial using inhaled nitric oxide.

PubMed

Lubitz, Andrea L; Sjoholm, Lars O; Goldberg, Amy; Pathak, Abhijit; Santora, Thomas; Sharp, Thomas E; Wallner, Markus; Berretta, Remus M; Poole, Lauren A; Wu, Jichuan; Wolfson, Marla R

2017-02-01

Hemorrhagic shock and pneumonectomy causes an acute increase in pulmonary vascular resistance (PVR). The increase in PVR and right ventricular (RV) afterload leads to acute RV failure, thus reducing left ventricular (LV) preload and output. Inhaled nitric oxide (iNO) lowers PVR by relaxing pulmonary arterial smooth muscle without remarkable systemic vascular effects. We hypothesized that with hemorrhagic shock and pneumonectomy, iNO can be used to decrease PVR and mitigate right heart failure. A hemorrhagic shock and pneumonectomy model was developed using sheep. Sheep received lung protective ventilatory support and were instrumented to serially obtain measurements of hemodynamics, gas exchange, and blood chemistry. Heart function was assessed with echocardiography. After randomization to study gas of iNO 20 ppm (n = 9) or nitrogen as placebo (n = 9), baseline measurements were obtained. Hemorrhagic shock was initiated by exsanguination to a target of 50% of the baseline mean arterial pressure. The resuscitation phase was initiated, consisting of simultaneous left pulmonary hilum ligation, via median sternotomy, infusion of autologous blood and initiation of study gas. Animals were monitored for 4 hours. All animals had an initial increase in PVR. PVR remained elevated with placebo; with iNO, PVR decreased to baseline. Echo showed improved RV function in the iNO group while it remained impaired in the placebo group. After an initial increase in shunt and lactate and decrease in SvO2, all returned toward baseline in the iNO group but remained abnormal in the placebo group. These data indicate that by decreasing PVR, iNO decreased RV afterload, preserved RV and LV function, and tissue oxygenation in this hemorrhagic shock and pneumonectomy model. This suggests that iNO may be a useful clinical adjunct to mitigate right heart failure and improve survival when trauma pneumonectomy is required.

Cardiopulmonary exercise testing and second-line pulmonary function tests to detect obstructive pattern in symptomatic smokers with borderline spirometry.

PubMed

Di Marco, Fabiano; Terraneo, Silvia; Job, Sara; Rinaldo, Rocco Francesco; Sferrazza Papa, Giuseppe Francesco; Roggi, Maria Adelaide; Santus, Pierachille; Centanni, Stefano

2017-06-01

The need for additional research on symptomatic smokers with normal spirometry has been recently emphasized. Albeit not meeting criteria for Chronic obstructive pulmonary disease (COPD) diagnosis, symptomatic smokers may experience activity limitation, evidence of airway disease, and exacerbations. We, therefore, evaluated whether symptomatic smokers with borderline spirometry (post-bronchodilator FEV 1 /FVC ratio between 5th to 20th percentile of predicted values) have pulmonary function abnormalities at rest and ventilatory constraints during exercise. 48 subjects (aged 60 ± 8 years, mean ± SD, 73% males, 16 healthy, and 17 symptomatic smokers) underwent cardiopulmonary exercise testing (CPET), body plethysmography, nitrogen single-breath washout test (N 2 SBW), lung diffusion for carbon monoxide (DLCO), and forced oscillation technique (FOT). Compared to healthy subjects, symptomatic smokers showed: 1) reduced breathing reserve (36 ± 17 vs. 49 ± 12%, P = 0.050); 2) exercise induced dynamic hyperinflation (-0.20 ± 0.17 vs. -0.03 ± 0.21 L, P = 0.043); 3) higher residual volume (158 ± 22 vs. 112 ± 22%, P < 0.001); 4) phase 3 slope at N 2 SBW (4.7 ± 2.1 vs. 1.4 ± 0.6%, P < 0.001); 5) no significant differences in DLCO and FOT results. In smokers with borderline spirometry, CPET and second-line pulmonary function tests may detect obstructive pattern. These subjects should be referred for second line testing, to obtain a diagnosis, or at least to clarify the mechanisms underlying symptoms. Whether the natural history of these patients is similar to COPD, and they deserve a similar therapeutic approach is worth investigating. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quantification of heterogeneity in lung disease with image-based pulmonary function testing.

PubMed

Stahr, Charlene S; Samarage, Chaminda R; Donnelley, Martin; Farrow, Nigel; Morgan, Kaye S; Zosky, Graeme; Boucher, Richard C; Siu, Karen K W; Mall, Marcus A; Parsons, David W; Dubsky, Stephen; Fouras, Andreas

2016-07-27

Computed tomography (CT) and spirometry are the mainstays of clinical pulmonary assessment. Spirometry is effort dependent and only provides a single global measure that is insensitive for regional disease, and as such, poor for capturing the early onset of lung disease, especially patchy disease such as cystic fibrosis lung disease. CT sensitively measures change in structure associated with advanced lung disease. However, obstructions in the peripheral airways and early onset of lung stiffening are often difficult to detect. Furthermore, CT imaging poses a radiation risk, particularly for young children, and dose reduction tends to result in reduced resolution. Here, we apply a series of lung tissue motion analyses, to achieve regional pulmonary function assessment in β-ENaC-overexpressing mice, a well-established model of lung disease. The expiratory time constants of regional airflows in the segmented airway tree were quantified as a measure of regional lung function. Our results showed marked heterogeneous lung function in β-ENaC-Tg mice compared to wild-type littermate controls; identified locations of airway obstruction, and quantified regions of bimodal airway resistance demonstrating lung compensation. These results demonstrate the applicability of regional lung function derived from lung motion as an effective alternative respiratory diagnostic tool.

Ventilatory Cycle Measurements and Loop Gain in Central Apnea in Mining Drivers Exposed to Intermittent Altitude

PubMed Central

Rey de Castro, Jorge; Liendo, Alicia; Ortiz, Oswaldo; Rosales-Mayor, Edmundo; Liendo, César

2017-01-01

Study Objectives: By measuring the apnea length, ventilatory phase, respiratory cycle length, and loop gain, we can further characterize the central apneas of high altitude (CAHA). Methods: Sixty-three drivers of all-terrain vehicles, working in a Peruvian mine located at 2,020 meters above sea level (MASL), were evaluated. A respiratory polygraph was performed in the first night they slept at high altitude. None of the subjects were exposed to oxygen during the test or acetazolamide in the preceding days of the test. Results: Sixty-three respiratory polygraphs were performed, and 59 were considered for analysis. Forty-six (78%) were normal, 6 (10%) had OSA, and 7 (12%) had CAHA. Key data from subjects include: residing altitude: 341 ± 828 MASL, Lake Louise scoring: 0.4 ± 0.8, Epworth score: 3.4 ± 2.7, apneahypopnea index: 35.7 ± 19.3, CA index: 13.4 ± 14.2, CA length: 14.4 ± 3.6 sec, ventilatory length: 13.5 ± 2.9 sec, cycle length: 26.5 ± 4.0 sec, ventilatory length/CA length ratio 0.9 ± 0.3 and circulatory delay 13.3 ± 2.9 sec. Duty ratio media [ventilatory duration/cycle duration] was 0.522 ± 0 0.128 [0.308–0.700] and loop gain was calculated from the duty ratio utilizing this formula: LG = 2π / [(2πDR-sin(2πDR)]. All subjects have a high loop gain media 2.415 ± 1.761 [1.175–6.260]. Multiple correlations were established with loop gain values, but the only significant correlation detected was between central apnea index and loop gain. Conclusions: Twelve percent of the studied population had CAHA. Measurements of respiratory cycle in workers with CAHA are more similar to idiopathic central apneas rather than Hunter-Cheyne-Stokes respiration. Also, there was a high degree of correlation between severity of central apnea and the degree of loop gain. The abnormal breathing patterns in those subjects could affect the sleep quality and potentially increase the risk for work accidents. Citation: Rey de Castro J, Liendo A, Ortiz O, Rosales-Mayor E, Liendo C. Ventilatory cycle measurements and loop gain in central apnea in mining drivers exposed to intermittent altitude. J Clin Sleep Med. 2017;13(1):27–32. PMID:27707449

Exercise training effects on hypoxic and hypercapnic ventilatory responses in mice selected for increased voluntary wheel running.

PubMed

Kelly, Scott A; Rezende, Enrico L; Chappell, Mark A; Gomes, Fernando R; Kolb, Erik M; Malisch, Jessica L; Rhodes, Justin S; Mitchell, Gordon S; Garland, Theodore

2014-02-01

What is the central question of this study? We used experimental evolution to determine how selective breeding for high voluntary wheel running and exercise training (7-11 weeks) affect ventilatory chemoreflexes of laboratory mice at rest. What is the main finding and its importance? Selective breeding, although significantly affecting some traits, did not systematically alter ventilation across gas concentrations. As with most human studies, our findings support the idea that endurance training attenuates resting ventilation. However, little evidence was found for a correlation between ventilatory chemoreflexes and the amount of individual voluntary wheel running. We conclude that exercise 'training' alters respiratory behaviours, but these changes may not be necessary to achieve high levels of wheel running. Ventilatory control is affected by genetics, the environment and gene-environment and gene-gene interactions. Here, we used an experimental evolution approach to test whether 37 generations of selective breeding for high voluntary wheel running (genetic effects) and/or long-term (7-11 weeks) wheel access (training effects) alter acute respiratory behaviour of mice resting in normoxic, hypoxic and hypercapnic conditions. As the four replicate high-runner (HR) lines run much more than the four non-selected control (C) lines, we also examined whether the amount of exercise among individual mice was a quantitative predictor of ventilatory chemoreflexes at rest. Selective breeding and/or wheel access significantly affected several traits. In normoxia, HR mice tended to have lower mass-adjusted rates of oxygen consumption and carbon dioxide production. Chronic wheel access increased oxygen consumption and carbon dioxide production in both HR and C mice during hypercapnia. Breathing frequency and minute ventilation were significantly reduced by chronic wheel access in both HR and C mice during hypoxia. Selection history, while significantly affecting some traits, did not systematically alter ventilation across all gas concentrations. As with most human studies, our findings support the idea that endurance training (access to wheel running) attenuates resting ventilation. However, little evidence was found for a correlation at the level of the individual variation between ventilatory chemoreflexes and performance (amount of individual voluntary wheel running). We tentatively conclude that exercise 'training' alters respiratory behaviours, but these changes may not be necessary to achieve high levels of wheel running.

Association between lung function and mental health problems among adults in the United States: findings from the First National Health and Nutrition Examination Survey.

PubMed

Goodwin, Renee D; Chuang, Shirley; Simuro, Nicole; Davies, Mark; Pine, Daniel S

2007-02-15

The objective of this study was to determine the association between lung function and mental health problems among adults in the United States. Data were drawn from the First National Health and Nutrition Examination Survey (1971-1975), with available information on a representative sample of US adults aged 25-74 years. Lung function was assessed by spirometry, and provisional diagnoses of restrictive and obstructive airway disease were assigned based on percentage of expected forced expiratory volume. Mental health problems were assessed with the General Well-Being scales. Restrictive lung function and obstructive lung function, compared with normal lung function, were each associated with a significantly increased likelihood of mental health problems. After adjustment for differences in demographic characteristics, obstructive lung function was associated with significantly lower overall well-being (p = 0.025), and restrictive lung function was associated with significantly lower overall well-being (p < 0.001), general health (p < 0.0001), vitality (p < 0.0001), and self-control (p = 0.001) and with higher depression (p = 0.002) subscale scores compared with no lung function problems. Consistent with previous findings from clinical and community-based studies, these results extend available data by providing evidence of a link between objectively measured lung function and self-reported mental health problems in a representative sample of community adults. Future studies are needed to determine the mechanisms of these associations.

Influence of Pulmonary Rehabilitation on Lung Function Changes After the Lung Resection for Primary Lung Cancer in Patients with Chronic Obstructive Pulmonary Disease.

PubMed

Mujovic, Natasa; Mujovic, Nebojsa; Subotic, Dragan; Ercegovac, Maja; Milovanovic, Andjela; Nikcevic, Ljubica; Zugic, Vladimir; Nikolic, Dejan

2015-11-01

Influence of physiotherapy on the outcome of the lung resection is still controversial. Study aim was to assess the influence of physiotherapy program on postoperative lung function and effort tolerance in lung cancer patients with chronic obstructive pulmonary disease (COPD) that are undergoing lobectomy or pneumonectomy. The prospective study included 56 COPD patients who underwent lung resection for primary non small-cell lung cancer after previous physiotherapy (Group A) and 47 COPD patients (Group B) without physiotherapy before lung cancer surgery. In Group A, lung function and effort tolerance on admission were compared with the same parameters after preoperative physiotherapy. Both groups were compared in relation to lung function, effort tolerance and symptoms change after resection. In patients with tumors requiring a lobectomy, after preoperative physiotherapy, a highly significant increase in FEV1, VC, FEF50 and FEF25 of 20%, 17%, 18% and 16% respectively was registered with respect to baseline values. After physiotherapy, a significant improvement in 6-minute walking distance was achieved. After lung resection, the significant loss of FEV1 and VC occurred, together with significant worsening of the small airways function, effort tolerance and symptomatic status. After the surgery, a clear tendency existed towards smaller FEV1 loss in patients with moderate to severe, when compared to patients with mild baseline lung function impairment. A better FEV1 improvement was associated with more significant loss in FEV1. Physiotherapy represents an important part of preoperative and postoperative treatment in COPD patients undergoing a lung resection for primary lung cancer.

Development of an Atlas of Strengths and Establishment of an Appropriate Model Structure

DTIC Science & Technology

1981-11-01

exercise hyperaemic response was greater for a given duration of contraction in water at 34 and 42*C than at lower temperatures. The rate of blood flow...Lambie, D.G. and Johnson, R.H. Ventilatory responses to sustained static forearm exercise in man. New Zealand Med. Journal; 1978, 88(618), 169...KEYWORDS: Static exercise , ventilatory responses . METHODS: Five healthy subjects were used to study the stimulus for hyperventilation which occurs during

Cardiac arrhythmias from a malpositioned Greenfield filter in a traumatic quadriplegic.

PubMed

Bach, J R; Zaneuski, R; Lee, H

1990-10-01

A case study is presented of premature Greenfield filter discharge with intracardiac migration and resulting life-threatening arrhythmias. These arrhythmias also interfered with the patient's transition from ventilatory support via orotracheal intubation to noninvasive positive airway pressure ventilatory support methods. The patient's arrhythmias were controlled by a demand cardiac pacemaker and cardiac glycoside therapy. No anticoagulants were used. She had no further filter migration nor significant complications for 16 months after hospital discharge.

Consequences of intrauterine growth restriction on ventilatory and thermoregulatory responses to asphyxia and hypercapnia in the newborn guinea-pig.

PubMed

Tolcos, Mary; Rees, Sandra; McGregor, Hugh; Walker, David

2002-01-01

The purpose of this study was to determine the effects of prenatal growth restriction on the ventilatory and thermoregulatory responses to asphyxia and hypercapnia in the newborn guinea-pig. Spontaneously growth-restricted (SGR) animals born to unoperated dams, and growth-retarded (GR) neonates born to dams in which a uterine artery had been ligated at mid gestation, were studied and compared with control neonates. Ventilatory responses to progressive asphyxia and steady-state hypercapnia were tested at 3-6 days of age using a barometric plethysmograph. The animals were then killed and the brains prepared for histological and immunohistochemical analysis. During progressive asphyxia, SGR neonates (n = 5) had a significantly increased minute ventilation compared with both control (n = 6) and GR (n = 5) neonates. Rectal temperature fell significantly in GR and SGR neonates after progressive asphyxia, but was unchanged in control neonates. The ventilatory responses to steady-state hypercapnia were not different in the GR, SGR and control neonates. The immunoreactive expression of glial fibrillary acidic protein, tyrosine hydroxylase, substance P and met-enkephalin in the medulla was also not different between the three groups. It was concluded that prenatal growth restriction is associated with alterations in the respiratory and thermoregulatory responses to asphyxia and hypercapnia, with greater effects observed when in utero growth restriction arises spontaneously, compared with that produced experimentally over approximately the last half of gestation.

Effect of upper airway CO2 pattern on ventilatory frequency in tegu lizards.

PubMed

Ballam, G O; Coates, E L

1989-07-01

Nasal CO2-sensitive receptors are reported to depress ventilatory frequency in several reptilian species in response to constant low levels of inspired CO2. The purpose of this study was to determine the influence of phasic patterns of CO2 in the upper airways on ventilation. Awake lizards (Tupinambis nigropunctatus) breathed through an endotracheal tube from an isolated gas source. A second gas mixture was forced at constant flow into the external nares. A concentration of 4% CO2 was intermittently pulsed through the nares in a square-wave pattern with a frequency of 60, 12, 6, 4.2, 1.8, and 0.6 cycles/min. Concentrations of 2, 3, 4, and 6% CO2 were also pulsed through the nares at 12 cycles/min and compared with sustained levels of 1, 1.5, 2, and 3%. Additionally, 0 or 3% CO2 was forced through the upper airways with a servo system designed to mimic normal ventilatory flow and gas concentrations. No changes in breathing pattern were noted during any of the pulsing protocols, although a significant breathing frequency depression was present with sustained levels of CO2 of comparable mean concentrations. We conclude that ventilatory control is selectively responsive to sustained levels of environmental CO2 but not to phasic changes in upper airway CO2 concentration.

Variation in Cilia Protein Genes and Progression of Lung Disease in Cystic Fibrosis.

PubMed

Blue, Elizabeth; Louie, Tin L; Chong, Jessica X; Hebbring, Scott J; Barnes, Kathleen C; Rafaels, Nicholas M; Knowles, Michael R; Gibson, Ronald L; Bamshad, Michael J; Emond, Mary J

2018-04-01

Cystic fibrosis, like primary ciliary dyskinesia, is an autosomal recessive disorder characterized by abnormal mucociliary clearance and obstructive lung disease. We hypothesized that genes underlying the development or function of cilia may modify lung disease severity in persons with cystic fibrosis. To test this hypothesis, we compared variants in 93 candidate genes in both upper and lower tertiles of lung function in a large cohort of children and adults with cystic fibrosis with those of a population control dataset. Variants within candidate genes were tested for association using the SKAT-O test, comparing cystic fibrosis cases defined by poor (n = 127) or preserved (n = 127) lung function with population controls (n = 3,269 or 3,148, respectively). Associated variants were then tested for association with related phenotypes in independent datasets. Variants in DNAH14 and DNAAF3 were associated with poor lung function in cystic fibrosis, whereas variants in DNAH14 and DNAH6 were associated with preserved lung function in cystic fibrosis. Associations between DNAH14 and lung function were replicated in disease-related phenotypes characterized by obstructive lung disease in adults. Genetic variants within DNAH6, DNAH14, and DNAAF3 are associated with variation in lung function among persons with cystic fibrosis.

Conservation of small-airway function by tacrolimus/cyclosporine conversion in the management of bronchiolitis obliterans following lung transplantation.

PubMed

Revell, M P; Lewis, M E; Llewellyn-Jones, C G; Wilson, I C; Bonser, R S

2000-12-01

We studied serial lung function in 11 patients with bronchiolitis obliterans syndrome who were treated with tacrolimus conversion following lung or heart-lung transplantation. Our results show that tacrolimus conversion slows the decline of lung function in bronchiolitis obliterans syndrome. The attenuation continues for at least 1 year following conversion.

Comparative analysis of the mechanical signals in lung development and compensatory growth.

PubMed

Hsia, Connie C W

2017-03-01

This review compares the manner in which physical stress imposed on the parenchyma, vasculature and thorax and the thoraco-pulmonary interactions, drive both developmental and compensatory lung growth. Re-initiation of anatomical lung growth in the mature lung is possible when the loss of functioning lung units renders the existing physiologic-structural reserves insufficient for maintaining adequate function and physical stress on the remaining units exceeds a critical threshold. The appropriate spatial and temporal mechanical interrelationships and the availability of intra-thoracic space, are crucial to growth initiation, follow-on remodeling and physiological outcome. While the endogenous potential for compensatory lung growth is retained and may be pharmacologically augmented, supra-optimal mechanical stimulation, unbalanced structural growth, or inadequate remodeling may limit functional gain. Finding ways to optimize the signal-response relationships and resolve structure-function discrepancies are major challenges that must be overcome before the innate compensatory ability could be fully realized. Partial pneumonectomy reproducibly removes a known fraction of functioning lung units and remains the most robust model for examining the adaptive mechanisms, structure-function consequences and plasticity of the remaining functioning lung units capable of regeneration. Fundamental mechanical stimulus-response relationships established in the pneumonectomy model directly inform the exploration of effective approaches to maximize compensatory growth and function in chronic destructive lung diseases, transplantation and bioengineered lungs.

Comparative Analysis of the Mechanical Signals in Lung Development and Compensatory Growth

PubMed Central

Hsia, Connie C.W.

2017-01-01

This review compares the manner in which physical stress imposed on the parenchyma, vasculature and thorax, and the thoraco-pulmonary interactions, drive both developmental and compensatory lung growth. Re-initiation of anatomical lung growth in the mature lung is possible when the loss of functioning lung units renders the existing physiologic-structural reserves insufficient for maintaining adequate function and physical stress on the remaining units exceeds a critical threshold. The appropriate spatial and temporal mechanical interrelationships, and the availability of intra-thoracic space, are crucial to growth initiation, follow-on remodeling and physiological outcome. While the endogenous potential for compensatory lung growth is retained and may be pharmacologically augmented, supra-optimal mechanical stimulation, unbalanced structural growth, or inadequate remodeling, may limit functional gain. Finding ways to optimize the signal-response relationships and resolve structure-function discrepancies are major challenges that must be overcome before the innate compensatory ability could be fully realized. Partial pneumonectomy reproducibly removes a known fraction of functioning lung units and remains the most robust model for examining the adaptive mechanisms, structure-function consequences, and plasticity of the remaining functioning lung units capable of regeneration. Fundamental mechanical stimulus-response relationships established in the pneumonectomy model directly inform the exploration of effective approaches to maximize compensatory growth and function in chronic destructive lung diseases, transplantation and bioengineered lungs. PMID:28084523

Quantitative computed tomography for the prediction of pulmonary function after lung cancer surgery: a simple method using simulation software.

PubMed

Ueda, Kazuhiro; Tanaka, Toshiki; Li, Tao-Sheng; Tanaka, Nobuyuki; Hamano, Kimikazu

2009-03-01

The prediction of pulmonary functional reserve is mandatory in therapeutic decision-making for patients with resectable lung cancer, especially those with underlying lung disease. Volumetric analysis in combination with densitometric analysis of the affected lung lobe or segment with quantitative computed tomography (CT) helps to identify residual pulmonary function, although the utility of this modality needs investigation. The subjects of this prospective study were 30 patients with resectable lung cancer. A three-dimensional CT lung model was created with voxels representing normal lung attenuation (-600 to -910 Hounsfield units). Residual pulmonary function was predicted by drawing a boundary line between the lung to be preserved and that to be resected, directly on the lung model. The predicted values were correlated with the postoperative measured values. The predicted and measured values corresponded well (r=0.89, p<0.001). Although the predicted values corresponded with values predicted by simple calculation using a segment-counting method (r=0.98), there were two outliers whose pulmonary functional reserves were predicted more accurately by CT than by segment counting. The measured pulmonary functional reserves were significantly higher than the predicted values in patients with extensive emphysematous areas (<-910 Hounsfield units), but not in patients with chronic obstructive pulmonary disease. Quantitative CT yielded accurate prediction of functional reserve after lung cancer surgery and helped to identify patients whose functional reserves are likely to be underestimated. Hence, this modality should be utilized for patients with marginal pulmonary function.

Mobile communication devices causing interference in invasive and noninvasive ventilators.

PubMed

Dang, Bao P; Nel, Pierre R; Gjevre, John A

2007-06-01

The aim of this study was to assess if common mobile communication systems would cause significant interference on mechanical ventilation devices and at what distances would such interference occur. We tested all the invasive and noninvasive ventilatory devices used within our region. This consisted of 2 adult mechanical ventilators, 1 portable ventilator, 2 pediatric ventilators, and 2 noninvasive positive pressure ventilatory devices. We operated the mobile devices from the 2 cellular communication systems (digital) and 1 2-way radio system used in our province at varying distances from the ventilators and looked at any interference they created. We tested the 2-way radio system, which had a fixed operation power output of 3.0 watts, the Global Systems for Mobile Communication cellular system, which had a maximum power output of 2.0 watts and the Time Division Multiple Access cellular system, which had a maximum power output of 0.2 watts on our ventilators. The ventilators were ventilating a plastic lung at fixed settings. The mobile communication devices were tested at varying distances starting at zero meter from the ventilator and in all operation modes. The 2-way radio caused the most interference on some of the ventilators, but the maximum distance of interference was 1.0 m. The Global Systems for Mobile Communication system caused significant interference only at 0 m and minor interference at 0.5 m on only 1 ventilator. The Time Division Multiple Access system caused no interference at all. Significant interference consisted of a dramatic rise and fluctuation of the respiratory rate, pressure, and positive end-expiratory pressure of the ventilators with no normalization when the mobile device was removed. From our experiment on our ventilators with the communication systems used in our province, we conclude that mobile communication devices such as cellular phones and 2-way radios are safe and cause no interference unless operated at very close distances of less than 1 meter.

Measurements of evaporated perfluorocarbon during partial liquid ventilation by a zeolite absorber.

PubMed

Proquitté, Hans; Rüdiger, Mario; Wauer, Roland R; Schmalisch, Gerd

2004-01-01

During partial liquid ventilation (PLV) the knowledge of the quantity of exhaled perfluorocarbon (PFC) allows a continuous substitution of the PFC loss to achieve a constant PFC level in the lungs. The aim of our in vitro study was to determine the PFC loss in the mixed expired gas by an absorber and to investigate the effect of the evaporated PFC on ventilatory measurements. To simulate the PFC loss during PLV, a heated flask was rinsed with a constant airflow of 4 L min(-1) and PFC was infused by different speeds (5, 10, 20 mL h(-1)). An absorber filled with PFC selective zeolites was connected with the flask to measure the PFC in the gas. The evaporated PFC volume and the PFC concentration were determined from the weight gain of the absorber measured by an electronic scale. The PFC-dependent volume error of the CO2SMO plus neonatal pneumotachograph was measured by manual movements of a syringe with volumes of 10 and 28 mL with a rate of 30 min(-1). Under steady state conditions there was a strong correlation (r2 = 0.999) between the infusion speed of PFC and the calculated PFC flow rate. The PFC flow rate was slightly underestimated by 4.3% (p < 0.01). However, this bias was independent from PFC infusion rate. The evaporated PFC volume was precisely measured with errors < 1%. The volume error of the CO2SMO-Plus pneumotachograph increased with increasing PFC content for both tidal volumes (p < 0.01). However for PFC flow rates up to 20 mL/h the error of the measured tidal volumes was < 5%. PFC selective zeolites can be used to quantify accurately the evaporated PFC volume during PLV. With increasing PFC concentrations in the exhaled air the measurement errors of ventilatory parameters have to be taken into account.

Ventilation is unstable during drowsiness before sleep onset.

PubMed

Thomson, Stuart; Morrell, Mary J; Cordingley, Jeremy J; Semple, Stephen J

2005-11-01

Ventilation is unstable during drowsiness before sleep onset. We have studied the effects of transitory changes in cerebral state during drowsiness on breath duration and lung volume in eight healthy subjects in the absence of changes in airway resistance and fluctuations of ventilation and CO2 tension, characteristic of the onset of non-rapid eye movement sleep. A volume-cycled ventilator in the assist control mode was used to maintain CO2 tension close to that when awake. Changes in cerebral state were determined by the EEG on a breath-by-breath basis and classified as alpha or theta breaths. Breath duration and the pause in gas flow between the end of expiratory airflow and the next breath were computed for two alpha breaths which preceded a theta breath and for the theta breath itself. The group mean (SD) results for this alpha-to-theta transition was associated with a prolongation in breath duration from 5.2 (SD 1.3) to 13.0 s (SD 2.1) and expiratory pause from 0.7 (SD 0.4) to 7.5 s (SD 2.2). Because the changes in arterial CO2 tension (PaCO2) are unknown during the theta breaths, we made in two subjects a continuous record of PaCO2 in the radial artery. PaCO2 remained constant from the alpha breaths through to the expiratory period of the theta breath by which time the duration of breath was already prolonged, representing an immediate and altered ventilatory response to the prevailing PaCO2. In the eight subjects, the CO2 tension awake was 39.6 Torr (SD 2.3) and on assisted ventilation 38.0 Torr (1.4). We conclude that the ventilatory instability recorded in the present experiments is due to the apneic threshold for CO2 being at or just below that when awake.

Effect of CO₂ on the ventilatory sensitivity to rising body temperature during exercise.

PubMed

Hayashi, Keiji; Honda, Yasushi; Miyakawa, Natsuki; Fujii, Naoto; Ichinose, Masashi; Koga, Shunsaku; Kondo, Narihiko; Nishiyasu, Takeshi

2011-05-01

We examined the degree to which ventilatory sensitivity to rising body temperature (the slope of the regression line relating ventilation and body temperature) is altered by restoration of arterial PCO(2) to the eucapnic level during prolonged exercise in the heat. Thirteen subjects exercised for ~60 min on a cycle ergometer at 50% of peak O(2) uptake with and without inhalation of CO(2)-enriched air. Subjects began breathing CO(2)-enriched air at the point that end-tidal Pco(2) started to decline. Esophageal temperature (T(es)), minute ventilation (V(E)), tidal volume (V(T)), respiratory frequency (f(R)), respiratory gases, middle cerebral artery blood velocity, and arterial blood pressure were recorded continuously. When V(E), V(T), f(R), and ventilatory equivalents for O(2) uptake (V(E)/VO(2)) and CO(2) output (V(E)/VCO(2)) were plotted against changes in T(es) from the start of the CO(2)-enriched air inhalation (ΔT(es)), the slopes of the regression lines relating V(E), V(T), V(E)/VO(2), and V(E)/VCO(2) to ΔT(es) (ventilatory sensitivity to rising body temperature) were significantly greater when subjects breathed CO(2)-enriched air than when they breathed room air (V(E): 19.8 ± 10.3 vs. 8.9 ± 6.7 l·min(-1)·°C(-1), V(T): 18 ± 120 vs. -81 ± 92 ml/°C; V(E)/VO(2): 7.4 ± 5.5 vs. 2.6 ± 2.3 units/°C, and V(E)/VCO(2): 7.6 ± 6.6 vs. 3.4 ± 2.8 units/°C). The increase in Ve was accompanied by increases in V(T) and f(R). These results suggest that restoration of arterial PCO(2) to nearly eucapnic levels increases ventilatory sensitivity to rising body temperature by around threefold.

The influence of weight loss on anaerobic threshold in obese women.

PubMed

Zak-Golab, Agnieszka; Zahorska-Markiewicz, Barbara; Langfort, Józef; Kocelak, Piotr; Holecki, Michal; Mizia-Stec, Katarzyna; Olszanecka-Glinianowicz, Magdalena; Chudek, Jerzy

2010-01-01

Obesity is associated with decreased physical activity. The aim of the study was to assess the anaerobic threshold in obese and normal weight women and to analyse the effect of weight-reduction therapy on the determined thresholds. 42 obese women without concomitant disease (age 30.5 ± 6.9y; BMI 33.6 ± 3.7 kg·m(-2)) and 19 healthy normal weight women (age 27.6 ± 7.0y; BMI 21.2 ± 1.9 kg·m(-2)) performed cycle ergometer incremental ramp exercise test up to exhaustion. The test was repeated in 19 obese women after 12.3 ± 4.2% weight loss. The lactate threshold (LT) and the ventilatory threshold (VT) were determined. Obese women had higher lactate (expressed as oxygen consumption) and ventilator threshold than normal weight women. The lactate threshold was higher than ventilatory one both in obese and normal weight women (1.11 ± 0.21 vs 0.88 ± 0.18 L·min(-1), p < 0.001; 0.94 ± 0.15 vs 0.79 ± 0.23 L·min(- 1), p < 0.01, respectively). After weight reduction therapy neither the lactate nor the ventilatory threshold changed significantly. The results concluded that; 1. The higher lactate threshold noted in obese women may be related to the increased fat acid usage in metabolism. 2. Both in obese and normal weight women lactate threshold appears at higher oxygen consumption than ventilatory threshold. 3. The obtained weight reduction, without weight normalisation was insufficient to cause significant changes of lactate and ventilatory thresholds in obese women. Key pointsResults showed that adolescent young female gymnasts have an altered serum inflammatory markers and endothelial activation, compared to their less physically active peers.Physical activities improved immune system.Differences in these biochemical data kept significant after adjustment for body weight and height.

Determinants of ventilation and pulmonary artery pressure during early acclimatization to hypoxia in humans.

PubMed

Fatemian, Marzieh; Herigstad, Mari; Croft, Quentin P P; Formenti, Federico; Cardenas, Rosa; Wheeler, Carly; Smith, Thomas G; Friedmannova, Maria; Dorrington, Keith L; Robbins, Peter A

2016-03-01

Pulmonary ventilation and pulmonary arterial pressure both rise progressively during the first few hours of human acclimatization to hypoxia. These responses are highly variable between individuals, but the origin of this variability is unknown. Here, we sought to determine whether the variabilities between different measures of response to sustained hypoxia were related, which would suggest a common source of variability. Eighty volunteers individually underwent an 8-h isocapnic exposure to hypoxia (end-tidal P(O2)=55 Torr) in a purpose-built chamber. Measurements of ventilation and pulmonary artery systolic pressure (PASP) assessed by Doppler echocardiography were made during the exposure. Before and after the exposure, measurements were made of the ventilatory sensitivities to acute isocapnic hypoxia (G(pO2)) and hyperoxic hypercapnia, the latter divided into peripheral (G(pCO2)) and central (G(cCO2)) components. Substantial acclimatization was observed in both ventilation and PASP, the latter being 40% greater in women than men. No correlation was found between the magnitudes of pulmonary ventilatory and pulmonary vascular responses. For G(pO2), G(pCO2) and G(cC O2), but not the sensitivity of PASP to acute hypoxia, the magnitude of the increase during acclimatization was proportional to the pre-acclimatization value. Additionally, the change in G(pO2) during acclimatization to hypoxia correlated well with most other measures of ventilatory acclimatization. Of the initial measurements prior to sustained hypoxia, only G(pCO2) predicted the subsequent rise in ventilation and change in G(pO2) during acclimatization. We conclude that the magnitudes of the ventilatory and pulmonary vascular responses to sustained hypoxia are predominantly determined by different factors and that the initial G(pCO2) is a modest predictor of ventilatory acclimatization. © 2015 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.

Factors affecting responses of infants with respiratory distress syndrome to exogenous surfactant therapy.

PubMed

Ho, N K

1993-02-01

Approximately 20% to 30% of infants with respiratory distress syndrome (RDS) do not respond to surfactant replacement therapy. Unfortunately there is no uniform definition of 'response' or 'non-response' to surfactant therapy. Response was based on improvement in a/A PO2 and/or mean airway pressure (MAP) by some and on improvement in FIO2 and/or MAP by others. Even the point of time at which evaluation of response was done is different in various reports. There is an urgent need to adopt an uniform definition. Most premature babies are surfactant deficient which is the aetiological factor of RDS. Generally good antenatal care and perinatal management are essential in avoidance of premature birth. Babies with lung hypoplasia and who are extremely premature (less than 24 weeks of gestation) do not respond well to exogenous surfactant replacement because of structural immaturity. Prompt management of asphyxiated birth and shock are necessary as there may be negative response to surfactant replacement. Foetal exposure to glucocorticoids improves responsiveness to postnatal administration of surfactant. Antenatal steroid therapy has become an important part of management of RDS with surfactant replacement. The premature lungs with high alveolar permeability tend to develop pulmonary oedema. With the presence of plasma-derived surfactant inhibitors, the response to exogenous surfactant may be affected. These inhibitors may also be released following ventilator barotrauma. The standard of neonatal intensive care such as ventilatory techniques has an important bearing on the outcome of the RDS babies.(ABSTRACT TRUNCATED AT 250 WORDS)

The etiology of occupational pulmonary aluminosis--the past and the present.

PubMed

Smolkova, Petra; Nakladalova, Marie

2014-12-01

The authors review pulmonary aluminosis caused by exposure to dust containing aluminium and its compounds, mainly oxides. Special attention is paid to various factors of occupational exposure as to an important etiologic issue. The condition has a rich and interesting history dating back to the 1930s. The most significant occupational exposures are associated with processes in bauxite smelting, the use of fine aluminium powder, exposure to aluminium welding fumes, grinding and polishing of aluminium materials. A literature search for relevant scientific studies in English was performed using the following internet databases: relevant sections of The Cochrane Library, EBSCO Discovery Service, Ovid, ProQuest Science Journals, PubMed, ScienceDirect, Scopus and Web of Knowledge. The initial clinical manifestations of pulmonary aluminosis are exertional dyspnea with dry, non-productive cough. Depending on the type and length of the occupational exposure, ventilatory defects may vary considerably from restrictive to obstructive pattern. Radiographic findings commonly showing nodular or slightly irregular opacities are predominantly located in the upper, less frequently in the lower lung fields, or can have a diffuse pattern. In advanced stages, severe pulmonary fibrosis with honeycombing occured. Although pulmonary aluminosis is a very rare disease, it still occurs. Since the industrial importance and use of aluminium continue to rise, lung damage from exposure to respirable aluminium particles should not be overlooked but monitored and prevented. Even today, the pathophysiology of pulmonary aluminosis has not been explained as yet.

[Allergic bronchopulmonary aspergillosis: Evaluation of a maintenance therapy with nebulized Ambisome®].

PubMed

Godet, C; Couturaud, F; Ragot, S; Laurent, F; Brun, A L; Bergeron, A; Cadranel, J

2017-05-01

Allergic bronchopulmonary aspergillosis (ABPA) affects 3-13% of patients with asthma. Its natural history includes possibly life-threatening exacerbations and evolution towards fixed obstructive ventilatory disorders or even irreversible lung fibrosis lesions. ABPA prognosis is directly associated with exacerbation control and the main objective of the treatment is to decrease their frequency and duration. Recommendations regarding dosage and duration of treatment are not very precise. The currently used combination of itraconazole and corticosteroid therapy has many limitations. The interests of a therapeutic strategy using nebulized liposomal amphotericin B (LAmB) are to heighten antifungal lung tissue concentration, to circumvent drug interactions and decrease the potential toxicity of systemic antifungal treatments. Finally, this association leads to improved eradication of Aspergillus, thereby limiting the risk of side effects and the emergence of treatment-resistant Aspergillus strains. This is a phase II, multicentre, randomized, single blind, controlled therapeutic study, with the objective of comparing the potential benefit on exacerbation control of a maintenance therapy by LAmB nebulization. The main objective of the study is to compare the incidence of severe clinical exacerbations in ABPA treatment, between a maintenance treatment strategy with nebulized LAmB and a conventional strategy without antifungal maintenance therapy. The results will guide practitioners in the management of ABPA treatments and help to define the place of aerosols of LAmB on "evidence base medicine" criteria. Copyright © 2017 SPLF. Published by Elsevier Masson SAS. All rights reserved.

Exposure to particulate matter in traffic: A comparison of cyclists and car passengers

NASA Astrophysics Data System (ADS)

Int Panis, Luc; de Geus, Bas; Vandenbulcke, Grégory; Willems, Hanny; Degraeuwe, Bart; Bleux, Nico; Mishra, Vinit; Thomas, Isabelle; Meeusen, Romain

2010-06-01

Emerging evidence suggests that short episodes of high exposure to air pollution occur while commuting. These events can result in potentially adverse health effects. We present a quantification of the exposure of car passengers and cyclists to particulate matter (PM). We have simultaneously measured concentrations (PNC, PM2.5 and PM10) and ventilatory parameters (minute ventilation (VE), breathing frequency and tidal volume) in three Belgian locations (Brussels, Louvain-la-Neuve and Mol) for 55 persons (38 male and 17 female). Subjects were first driven by car and then cycled along identical routes in a pairwise design. Concentrations and lung deposition of PNC and PM mass were compared between biking trips and car trips. Mean bicycle/car ratios for PNC and PM are close to 1 and rarely significant. The size and magnitude of the differences in concentrations depend on the location which confirms similar inconsistencies reported in literature. On the other hand, the results from this study demonstrate that bicycle/car differences for inhaled quantities and lung deposited dose are large and consistent across locations. These differences are caused by increased VE in cyclists which significantly increases their exposure to traffic exhaust. The VE while riding a bicycle is 4.3 times higher compared to car passengers. This aspect has been ignored or severely underestimated in previous studies. Integrated health risk evaluations of transport modes or cycling policies should therefore use exposure estimates rather than concentrations.

Outcomes of intensive care unit care in adults with cystic fibrosis.

PubMed

Sood, N; Paradowski, L J; Yankaskas, J R

2001-02-01

Cystic fibrosis (CF) causes progressive respiratory failure and death in more than 90% of patients. Mechanical ventilation has been discouraged in CF because of poor outcomes, but improved survival and the availability of lung transplantation have increased the indications for care of CF patients in the intensive care unit (ICU). We studied the outcomes of all CF patients admitted to the University of North Carolina Hospitals Medical ICU from January 1990 through December 1998. Seventy-six patients, ranging in ages from 17 to 45 yr (mean: 27 yr), and of whom 53% were female, had 136 admissions for exacerbations of CF with respiratory failure (RF, n = 65), hemoptysis (n = 33), antibiotic desensitization (n = 30), pneumothorax (n = 3), or other reasons (n = 5). Eighty-six percent of the patients with hemoptysis and all of those with desensitization and pneumothorax were alive 1 yr after ICU discharge. Of the 42 patients with RF, 37 (88%) required assisted ventilation. Twenty-three (55%) of the patients with RF survived to ICU discharge and 19 (45%) died. Seventeen (40%) of the patients with RF received lung transplants and 14 were alive 1 yr later. Without transplantation, three (7%) of the patients with RF were alive and three (7%) were dead 1 yr later. Sex, body mass index, and respiratory bacteria did not correlate with survival. We conclude that ICU care for adults with CF who have reversible complications is appropriate and effective. Ventilatory support is appropriate for some transplant candidates.

Ultra-modified rapid sequence induction with transnasal humidified rapid insufflation ventilatory exchange: Challenging convention.

PubMed

Kulkarni, Ketan Sakharam; Dave, Nandini; Saran, Shriyam; Garasia, Madhu; Parelkar, Sandesh

2018-04-01

During positive pressure ventilation, gastric inflation and subsequent pulmonary aspiration can occur. Rapid sequence induction (RSI) technique is an age-old formula to prevent this. We adopted a novel approach of RSI for patients with high risk of aspiration and evaluated it further in patients undergoing laparoscopic surgeries. We believe that, in patients with risk of gastric insufflation and pulmonary aspiration, transnasal humidified rapid-insufflation ventilatory exchange can be useful in facilitating pre- and apnoeic oxygenation till tracheal isolation is achieved.

Structural basis for pulmonary functional imaging.

PubMed

Itoh, H; Nakatsu, M; Yoxtheimer, L M; Uematsu, H; Ohno, Y; Hatabu, H

2001-03-01

An understanding of fine normal lung morphology is important for effective pulmonary functional imaging. The lung specimens must be inflated. These include (a) unfixed, inflated lung specimen, (b) formaldehyde fixed lung specimen, (c) fixed, inflated dry lung specimen, and (d) histology specimen. Photography, magnified view, radiograph, computed tomography, and histology of these specimens are demonstrated. From a standpoint of diagnostic imaging, the main normal lung structures consist of airways (bronchi and bronchioles), alveoli, pulmonary vessels, secondary pulmonary lobules, and subpleural pulmonary lymphatic channels. This review summarizes fine radiologic normal lung morphology as an aid to effective pulmonary functional imaging.

Dosimetric feasibility of 4DCT-ventilation imaging guided proton therapy for locally advanced non-small-cell lung cancer.

PubMed

Huang, Qijie; Jabbour, Salma K; Xiao, Zhiyan; Yue, Ning; Wang, Xiao; Cao, Hongbin; Kuang, Yu; Zhang, Yin; Nie, Ke

2018-04-25

The principle aim of this study is to incorporate 4DCT ventilation imaging into functional treatment planning that preserves high-functioning lung with both double scattering and scanning beam techniques in proton therapy. Eight patients with locally advanced non-small-cell lung cancer were included in this study. Deformable image registration was performed for each patient on their planning 4DCTs and the resultant displacement vector field with Jacobian analysis was used to identify the high-, medium- and low-functional lung regions. Five plans were designed for each patient: a regular photon IMRT vs. anatomic proton plans without consideration of functional ventilation information using double scattering proton therapy (DSPT) and intensity modulated proton therapy (IMPT) vs. functional proton plans with avoidance of high-functional lung using both DSPT and IMPT. Dosimetric parameters were compared in terms of tumor coverage, plan heterogeneity, and avoidance of normal tissues. Our results showed that both DSPT and IMPT plans gave superior dose advantage to photon IMRTs in sparing low dose regions of the total lung in terms of V5 (volume receiving 5Gy). The functional DSPT only showed marginal benefit in sparing high-functioning lung in terms of V5 or V20 (volume receiving 20Gy) compared to anatomical plans. Yet, the functional planning in IMPT delivery, can further reduce the low dose in high-functioning lung without degrading the PTV dosimetric coverages, compared to anatomical proton planning. Although the doses to some critical organs might increase during functional planning, the necessary constraints were all met. Incorporating 4DCT ventilation imaging into functional proton therapy is feasible. The functional proton plans, in intensity modulated proton delivery, are effective to further preserve high-functioning lung regions without degrading the PTV coverage.

Quantitative computed tomography of lung parenchyma in patients with emphysema: analysis of higher-density lung regions

NASA Astrophysics Data System (ADS)

Lederman, Dror; Leader, Joseph K.; Zheng, Bin; Sciurba, Frank C.; Tan, Jun; Gur, David

2011-03-01

Quantitative computed tomography (CT) has been widely used to detect and evaluate the presence (or absence) of emphysema applying the density masks at specific thresholds, e.g., -910 or -950 Hounsfield Unit (HU). However, it has also been observed that subjects with similar density-mask based emphysema scores could have varying lung function, possibly indicating differences of disease severity. To assess this possible discrepancy, we investigated whether density distribution of "viable" lung parenchyma regions with pixel values > -910 HU correlates with lung function. A dataset of 38 subjects, who underwent both pulmonary function testing and CT examinations in a COPD SCCOR study, was assembled. After the lung regions depicted on CT images were automatically segmented by a computerized scheme, we systematically divided the lung parenchyma into different density groups (bins) and computed a number of statistical features (i.e., mean, standard deviation (STD), skewness of the pixel value distributions) in these density bins. We then analyzed the correlations between each feature and lung function. The correlation between diffusion lung capacity (DLCO) and STD of pixel values in the bin of -910HU <= PV < -750HU was -0.43, as compared with a correlation of -0.49 obtained between the post-bronchodilator ratio (FEV1/FVC) measured by the forced expiratory volume in 1 second (FEV1) dividing the forced vital capacity (FVC) and the STD of pixel values in the bin of -1024HU <= PV < -910HU. The results showed an association between the distribution of pixel values in "viable" lung parenchyma and lung function, which indicates that similar to the conventional density mask method, the pixel value distribution features in "viable" lung parenchyma areas may also provide clinically useful information to improve assessments of lung disease severity as measured by lung functional tests.

Effects of inhaled fenoterol and positive end-expiratory pressure on the respiratory mechanics of patients with chronic obstructive pulmonary disease.

PubMed

Guérin, Claude; Durand, Pierre-Guy; Pereira, Cécile; Richard, Jean-Christophe; Poupelin, Jean-Charles; Lemasson, Stéphane; Badet, Michel; Philit, François; Vecellio, Laurent; Chantrel, Gilles

2005-09-01

During acute ventilatory failure in patients with chronic obstructive pulmonary disease (COPD), applying external positive end-expiratory pressure (PEEPe) will reopen small airways and, thus, may enhance peripheral deposition as well as the physiological effects of inhaled beta-2 agonists. To investigate the efficacy of inhaled fenoterol applied by zero end-expiratory pressure (ZEEPe) or PEEPe. Ten patients with COPD who were intubated and mechanically ventilated received fenoterol (10 mg/4 mL) via the ventilator using a jet nebulizer for 30 min on ZEEPe and PEEPe set at 80% of the total PEEP in a random order. The total resistance of the respiratory system (rapid airway occlusion technique), change in end-expiratory lung volume and expiratory flow limitation were assessed before and 5 min, 15 min, 30 min, 60 min and 240 min after fenoterol inhalation. Before inhalation and 60 min after inhalation, the total PEEP, the change in end-expiratory lung volume and the total resistance of the respiratory system were 8+/-3 cmH2O and 6+/-3 cmH2O, 0.61+/-0.34 L and 0.43+/-0.32 L, and 26+/-7 cmH2O/L/s and 23+/-6 cmH2O/L/s, respectively, with ZEEPe, and 9+/-3 cmH2O and 8+/-3 cmH2O (P<0.05 versus ZEEPe), 0.62+/-0.34 L and 0.62+/-0.37 L (P<0.05 versus ZEEPe), and 26+/-9 H2O/L/s and 25+/-9 H2O/L/s, respectively, with PEEPe. Three patients became not flow-limited under the combination of PEEPe and fenoterol. In patients with COPD, fenoterol combined with PEEPe has opposing effects on respiratory mechanics. First, it does not significantly reduce lung hyperinflation or inspiratory resistances. Second, it allows expiratory flow limitation reversal in some patients. These findings result from the net effect on end-expiratory lung volume of each intervention. This implies that if fenoterol is used in combination with PEEPe, the level of PEEPe should be reassessed during the time course of the drug to prevent any further lung hyperinflation.

Scintigraphy at 3 months after single lung transplantation and observations of primary graft dysfunction and lung function.

PubMed

Belmaati, Esther Okeke; Iversen, Martin; Kofoed, Klaus F; Nielsen, Michael B; Mortensen, Jann

2012-06-01

Scintigraphy has been used as a tool to detect dysfunction of the lung before and after transplantation. The aims of this study were to evaluate the development of the ventilation-perfusion relationships in single lung transplant recipients in the first year, at 3 months after transplantation, and to investigate whether scintigraphic findings at 3 months were predictive for the outcome at 12 months in relation to primary graft dysfunction (PGD) and lung function. A retrospective study was carried out on all patients who prospectively and consecutively were referred for a routine lung scintigraphy procedure 3 months after single lung transplantation (SLTX). A total of 41 patients were included in the study: 20 women and 21 men with the age span of patients at transplantation being 38-66 years (mean ± SD: 54.2 ± 6.0). Patient records also included lung function tests and chest X-ray images. We found no significant correlation between lung function distribution at 3 months and PGD at 72 h. There was also no significant correlation between PGD scores at 72 h and lung function at 6 and 12 months. The same applied to scintigraphic scores for heterogeneity at 3 months compared with lung function at 6 and 12 months. Fifty-five percent of all patients had decreased ventilation function measured in the period from 6 to 12 months. Forty-nine percent of the patients had normal perfusion evaluations, and 51% had abnormal perfusion evaluations at 3 months. For ventilation evaluations, 72% were normal and 28% were abnormal. There was a significant difference in the normal versus abnormal perfusion and ventilation scintigraphic images evaluated from the same patients. Ventilation was distributed more homogenously in the transplanted lung than perfusion in the same lung. The relative distribution of perfusion and ventilation to the transplanted lung of patients with and without a primary diagnosis of fibrosis did not differ significantly from each other. We conclude that PGD defined at 72 h does not lead to recognizable changes in ventilation-perfusion scintigrapy at 3 months, and scintigraphic findings do not correlate with development in lung function in the first 12 months.

Cost of ventilation and effect of digestive state on the ventilatory response of the tegu lizard.

PubMed

Skovgaard, Nini; Wang, Tobias

2004-07-12

We performed simultaneous measurements of ventilation, oxygen uptake and carbon dioxide production in the South American lizard, Tupinambis merianae, equipped with a mask and maintained at 25 degrees C. Ventilation of resting animals was stimulated by progressive exposure to hypercapnia (2, 4 and 6%) or hypoxia (15, 10, 8 and 6%) in inspired gas mixture. This was carried out in both fasting and digesting animals. The ventilatory response to hypercapnia and hypoxia were affected by digestive state, with a more vigorous ventilatory response in digesting animals compared to fasting animals. Hypoxia doubled total ventilation while hypercapnia led to a four-fold increase in total ventilation both accomplished through an increase in tidal volume. Oxygen uptake remained constant during all hypercapnic exposures while there was an increase during hypoxia. Cost of ventilation was estimated to be 17% during hypoxia but less than 1% during hypercapnia. Our data indicate that ventilation can be greatly elevated at a small energetic cost.

Regional Lung Function Profiles of Stage I and III Lung Cancer Patients: An Evaluation for Functional Avoidance Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vinogradskiy, Yevgeniy, E-mail: yevgeniy.vinogradskiy@ucdenver.edu; Schubert, Leah; Diot, Quentin

2016-07-15

Purpose: The development of clinical trials is underway to use 4-dimensional computed tomography (4DCT) ventilation imaging to preferentially spare functional lung in patients undergoing radiation therapy. The purpose of this work was to generate data to aide with clinical trial design by retrospectively characterizing dosimetric and functional profiles for patients with different stages of lung cancer. Methods and Materials: A total of 118 lung cancer patients (36% stage I and 64% stage III) from 2 institutions were used for the study. A 4DCT-ventilation map was calculated using the patient's 4DCT imaging, deformable image registration, and a density-change–based algorithm. To assessmore » each patient's spatial ventilation profile both quantitative and qualitative metrics were developed, including an observer-based defect observation and metrics based on the ventilation in each lung third. For each patient we used the clinical doses to calculate functionally weighted mean lung doses and metrics that assessed the interplay between the spatial location of the dose and high-functioning lung. Results: Both qualitative and quantitative metrics revealed a significant difference in functional profiles between the 2 stage groups (P<.01). We determined that 65% of stage III and 28% of stage I patients had ventilation defects. Average functionally weighted mean lung dose was 19.6 Gy and 5.4 Gy for stage III and I patients, respectively, with both groups containing patients with large spatial overlap between dose and high-function regions. Conclusion: Our 118-patient retrospective study found that 65% of stage III patients have regionally variant ventilation profiles that are suitable for functional avoidance. Our results suggest that regardless of disease stage, it is possible to have unique spatial interplay between dose and high-functional lung, highlighting the importance of evaluating the function of each patient and developing a personalized functional avoidance treatment approach.« less

Management of acute respiratory failure in interstitial lung diseases: overview and clinical insights.

PubMed

Faverio, Paola; De Giacomi, Federica; Sardella, Luca; Fiorentino, Giuseppe; Carone, Mauro; Salerno, Francesco; Ora, Jousel; Rogliani, Paola; Pellegrino, Giulia; Sferrazza Papa, Giuseppe Francesco; Bini, Francesco; Bodini, Bruno Dino; Messinesi, Grazia; Pesci, Alberto; Esquinas, Antonio

2018-05-15

Interstitial lung diseases (ILDs) are a heterogeneous group of diseases characterized by widespread fibrotic and inflammatory abnormalities of the lung. Respiratory failure is a common complication in advanced stages or following acute worsening of the underlying disease. Aim of this review is to evaluate the current evidence in determining the best management of acute respiratory failure (ARF) in ILDs. A literature search was performed in the Medline/PubMed and EMBASE databases to identify studies that investigated the management of ARF in ILDs (the last search was conducted on November 2017). In managing ARF, it is important to establish an adequate diagnostic and therapeutic management depending on whether the patient has an underlying known chronic ILD or ARF is presenting in an unknown or de novo ILD. In the first case both primary causes, such as acute exacerbations of the disease, and secondary causes, including concomitant pulmonary infections, fluid overload and pulmonary embolism need to be investigated. In the second case, a diagnostic work-up that includes investigations in regards to ILD etiology, such as autoimmune screening and bronchoalveolar lavage, should be performed, and possible concomitant causes of ARF have to be ruled out. Oxygen supplementation and ventilatory support need to be titrated according to the severity of ARF and patients' therapeutic options. High-Flow Nasal oxygen might potentially be an alternative to conventional oxygen therapy in patients requiring both high flows and high oxygen concentrations to correct hypoxemia and control dyspnea, however the evidence is still scarce. Neither Non-Invasive Ventilation (NIV) nor Invasive Mechanical Ventilation (IMV) seem to change the poor outcomes associated to advanced stages of ILDs. However, in selected patients, such as those with less severe ARF, a NIV trial might help in the early recognition of NIV-responder patients, who may present a better short-term prognosis. More invasive techniques, including IMV and Extracorporeal Membrane Oxygenation, should be limited to patients listed for lung transplant or with reversible causes of ARF. Despite the overall poor prognosis of ARF in ILDs, a personalized approach may positively influence patients' management, possibly leading to improved outcomes. However, further studies are warranted.

Application of mid-frequency ventilation in an animal model of lung injury: a pilot study.

PubMed

Mireles-Cabodevila, Eduardo; Chatburn, Robert L; Thurman, Tracy L; Zabala, Luis M; Holt, Shirley J; Swearingen, Christopher J; Heulitt, Mark J

2014-11-01

Mid-frequency ventilation (MFV) is a mode of pressure control ventilation based on an optimal targeting scheme that maximizes alveolar ventilation and minimizes tidal volume (VT). This study was designed to compare the effects of conventional mechanical ventilation using a lung-protective strategy with MFV in a porcine model of lung injury. Our hypothesis was that MFV can maximize ventilation at higher frequencies without adverse consequences. We compared ventilation and hemodynamic outcomes between conventional ventilation and MFV. This was a prospective study of 6 live Yorkshire pigs (10 ± 0.5 kg). The animals were subjected to lung injury induced by saline lavage and injurious conventional mechanical ventilation. Baseline conventional pressure control continuous mandatory ventilation was applied with V(T) = 6 mL/kg and PEEP determined using a decremental PEEP trial. A manual decision support algorithm was used to implement MFV using the same conventional ventilator. We measured P(aCO2), P(aO2), end-tidal carbon dioxide, cardiac output, arterial and venous blood oxygen saturation, pulmonary and systemic vascular pressures, and lactic acid. The MFV algorithm produced the same minute ventilation as conventional ventilation but with lower V(T) (-1 ± 0.7 mL/kg) and higher frequency (32.1 ± 6.8 vs 55.7 ± 15.8 breaths/min, P < .002). There were no differences between conventional ventilation and MFV for mean airway pressures (16.1 ± 1.3 vs 16.4 ± 2 cm H2O, P = .75) even when auto-PEEP was higher (0.6 ± 0.9 vs 2.4 ± 1.1 cm H2O, P = .02). There were no significant differences in any hemodynamic measurements, although heart rate was higher during MFV. In this pilot study, we demonstrate that MFV allows the use of higher breathing frequencies and lower V(T) than conventional ventilation to maximize alveolar ventilation. We describe the ventilatory or hemodynamic effects of MFV. We also demonstrate that the application of a decision support algorithm to manage MFV is feasible. Copyright © 2014 by Daedalus Enterprises.