Neurally adjusted ventilatory assist in patients with acute respiratory failure: study protocol for a randomized controlled trial.

PubMed

Villar, Jesús; Belda, Javier; Blanco, Jesús; Suarez-Sipmann, Fernando; Añón, José Manuel; Pérez-Méndez, Lina; Ferrando, Carlos; Parrilla, Dácil; Montiel, Raquel; Corpas, Ruth; González-Higueras, Elena; Pestaña, David; Martínez, Domingo; Fernández, Lorena; Soro, Marina; García-Bello, Miguel Angel; Fernández, Rosa Lidia; Kacmarek, Robert M

2016-10-13

Patient-ventilator asynchrony is a common problem in mechanically ventilated patients with acute respiratory failure. It is assumed that asynchronies worsen lung function and prolong the duration of mechanical ventilation (MV). Neurally Adjusted Ventilatory Assist (NAVA) is a novel approach to MV based on neural respiratory center output that is able to trigger, cycle, and regulate the ventilatory cycle. We hypothesized that the use of NAVA compared to conventional lung-protective MV will result in a reduction of the duration of MV. It is further hypothesized that NAVA compared to conventional lung-protective MV will result in a decrease in the length of ICU and hospital stay, and mortality. This is a prospective, multicenter, randomized controlled trial in 306 mechanically ventilated patients with acute respiratory failure from several etiologies. Only patients ventilated for less than 5 days, and who are expected to require prolonged MV for an additional 72 h or more and are able to breathe spontaneously, will be considered for enrollment. Eligible patients will be randomly allocated to two ventilatory arms: (1) conventional lung-protective MV (n = 153) and conventional lung-protective MV with NAVA (n = 153). Primary outcome is the number of ventilator-free days, defined as days alive and free from MV at day 28 after endotracheal intubation. Secondary outcomes are total length of MV, and ICU and hospital mortality. This is the first randomized clinical trial examining, on a multicenter scale, the beneficial effects of NAVA in reducing the dependency on MV of patients with acute respiratory failure. ClinicalTrials.gov website ( NCT01730794 ). Registered on 15 November 2012.

Application of positive airway pressure in restoring pulmonary function and thoracic mobility in the postoperative period of bariatric surgery: a randomized clinical trial

PubMed Central

Brigatto, Patrícia; Carbinatto, Jéssica C.; Costa, Carolina M.; Montebelo, Maria I. L.; Rasera-Júnior, Irineu; Pazzianotto-Forti, Eli M.

2014-01-01

Objective: To evaluate whether the application of bilevel positive airway pressure in the postoperative period of bariatric surgery might be more effective in restoring lung volume and capacity and thoracic mobility than the separate application of expiratory and inspiratory positive pressure. Method: Sixty morbidly obese adult subjects who were hospitalized for bariatric surgery and met the predefined inclusion criteria were evaluated. The pulmonary function and thoracic mobility were preoperatively assessed by spirometry and cirtometry and reevaluated on the 1st postoperative day. After preoperative evaluation, the subjects were randomized and allocated into groups: EPAP Group (n=20), IPPB Group (n=20) and BIPAP Group (n=20), then received the corresponding intervention: positive expiratory pressure (EPAP), inspiratory positive pressure breathing (IPPB) or bilevel inspiratory positive airway pressure (BIPAP), in 6 sets of 15 breaths or 30 minutes twice a day in the immediate postoperative period and on the 1st postoperative day, in addition to conventional physical therapy. Results: There was a significant postoperative reduction in spirometric variables (p<0.05), regardless of the technique used, with no significant difference among the techniques (p>0.05). Thoracic mobility was preserved only in group BIPAP (p>0.05), but no significant difference was found in the comparison among groups (p>0.05). Conclusion: The application of positive pressure does not seem to be effective in restoring lung function after bariatric surgery, but the use of bilevel positive pressure can preserve thoracic mobility, although this technique was not superior to the other techniques. PMID:25590448

Physiologic response to varying levels of pressure support and neurally adjusted ventilatory assist in patients with acute respiratory failure.

PubMed

Colombo, Davide; Cammarota, Gianmaria; Bergamaschi, Valentina; De Lucia, Marta; Corte, Francesco Della; Navalesi, Paolo

2008-11-01

Neurally adjusted ventilatory assist (NAVA) is a new mode wherein the assistance is provided in proportion to diaphragm electrical activity (EAdi). We assessed the physiologic response to varying levels of NAVA and pressure support ventilation (PSV). ICU of a University Hospital. Fourteen intubated and mechanically ventilated patients. DESIGN AND PROTOCOL: Cross-over, prospective, randomized controlled trial. PSV was set to obtain a VT/kg of 6-8 ml/kg with an active inspiration. NAVA was matched with a dedicated software. The assistance was decreased and increased by 50% with both modes. The six assist levels were randomly applied. Arterial blood gases (ABGs), tidal volume (VT/kg), peak EAdi, airway pressure (Paw), neural and flow-based timing. Asynchrony was calculated using the asynchrony index (AI). There was no difference in ABGs regardless of mode and assist level. The differences in breathing pattern, ventilator assistance, and respiratory drive and timing between PSV and NAVA were overall small at the two lower assist levels. At the highest assist level, however, we found greater VT/kg (9.1 +/- 2.2 vs. 7.1 +/- 2 ml/kg, P < 0.001), and lower breathing frequency (12 +/- 6 vs. 18 +/- 8.2, P < 0.001) and peak EAdi (8.6 +/- 10.5 vs. 12.3 +/- 9.0, P < 0.002) in PSV than in NAVA; we found mismatch between neural and flow-based timing in PSV, but not in NAVA. AI exceeded 10% in five (36%) and no (0%) patients with PSV and NAVA, respectively (P < 0.05). Compared to PSV, NAVA averted the risk of over-assistance, avoided patient-ventilator asynchrony, and improved patient-ventilator interaction.

Professional figures in intermediate intensive units.

PubMed

Quadri, A; Simoni, P; Clini, E; Errera, D; Foglio, K; Vitacca, M; Schena, M

1994-12-01

In Italy, respiratory intermediate intensive care units (IICUs) are not yet considered as autonomous hospital departments. The IICU of the Rehabilitation Department of the Medical Centre of Gussago (12 monitored beds) provides care for respiratory and cardiac patients. Ventilatory assistance and noninvasive modalities both in treatment and monitoring suggest a multidisciplinary approach to the patient. Highly professional figures should, therefore, be singled out to provide care in a respiratory IICU. The medical staff is composed of one anaesthesiologist, one cardiologist and one pulmonologist, who can integrate care when respiratory complications occur in a cardiological patient, or when cardiac events affect a respiratory patient. Nurses are capable of specific activities, especially when ventilatory assistance is required. The presence of a physiotherapist reduces the nursing workload, especially for ventilated individuals. The psychological aspect is undertaken by a specialist. Finally, an expert in nutrition provides an individualized dietary regimen. Our 4 year experience encourages such a multidisciplinary approach. An ideal integration of the professional activities should provide adequate and individual care for patients admitted to an IICU.

[Types of ventilatory support and their indications in amyotrophic lateral sclerosis].

PubMed

Perrin, C

2006-06-01

Respiratory muscle weakness represents the major cause of mortality in patients with amyotrophic lateral sclerosis (ALS). As a result, ventilatory assistance is an important part of disease management. Nowadays, noninvasive ventilation (NIV) has become the first choice modality for most patients and represents an alternative to tracheostomy intermittent positive-pressure ventilation. Although, some consensus guidelines have been proposed to initiate NIV in patients with restrictive chronic respiratory failure, these criteria are discussed regarding ALS. While the current consensus recommends that NIV may be used in symptomatic patients with hypercapnia or forced vital capacity<50p.cent of predicted value, early use of NIV is proposed in the literature and reported in this paper.

Severity of nocturnal hypoxia and daytime hypercapnia predicts CPAP failure in patients with COPD and obstructive sleep apnea overlap syndrome.

PubMed

Kuklisova, Zuzana; Tkacova, Ruzena; Joppa, Pavol; Wouters, Emiel; Sastry, Manuel

2017-02-01

Obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) are independent risk factors for cardiovascular diseases. In patients with OSA and concurrent COPD, continuous positive airway pressure (CPAP) therapy improves survival. Nevertheless, a significant proportion of such patients do not tolerate CPAP. The aim of the present study was to analyze early predictors of CPAP failure in patients with OSA and concurrent COPD, and to evaluate the effects of bilevel positive airway pressure (BiPAP) in this high-risk group of patients. A post hoc analysis from the database of 2100 patients diagnosed with OSA between 2012 and 2014 identified 84 subjects as having concomitant COPD and meeting inclusion criteria. Demographic data, pulmonary function tests, OSA parameters, blood gases, response to CPAP and BiPAP titration, and two months of therapy were collected. A multivariate model was generated to find determinants of CPAP failure. Primary CPAP failure was found in 23% of patients who were more obese (p = 0.018), had worse lung function, lower PO 2 (p = 0.023) and higher PCO 2 while awake (p < 0.001), and more sleep time with an SpO 2  < 90% (CT90%) (p < 0.001) compared to those who responded to CPAP. In multivariate analysis, PCO 2 while awake [odds ratio (OR) 29.5, confidence interval (CI) 2.22-391, p = 0.010] and CT90% (OR 1.06, CI 1.01-1.11, p = 0.017) independently predicted CPAP failure after adjustments for covariates. The BiPAP therapy was well tolerated and effectively alleviated hypercapnia in all patients with primary CPAP failure. Daytime hypercapnia and nocturnal hypoxia are independent predictors of early CPAP failure in patients with the OSA-COPD overlap syndrome. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of Modes, Obesity, and Body Position on Non-invasive Positive Pressure Ventilation Success in the Intensive Care Unit: A Randomized Controlled Study.

PubMed

Türk, Murat; Aydoğdu, Müge; Gürsel, Gül

2018-01-01

Different outcomes and success rates of non-invasive positive pressure ventilation (NPPV) in patients with acute hypercapnic respiratory failure (AHRF) still pose a significant problem in intensive care units. Previous studies investigating different modes, body positioning, and obesity-associated hypoventilation in patients with chronic respiratory failure showed that these factors may affect ventilator mechanics to achieve a better minute ventilation. This study tried to compare pressure support (BiPAP-S) and average volume targeted pressure support (AVAPS-S) modes in patients with acute or acute-on-chronic hypercapnic respiratory failure. In addition, short-term effects of body position and obesity within both modes were analyzed. We conducted a randomized controlled study in a 7-bed intensive care unit. The course of blood gas analysis and differences in ventilation variables were compared between BiPAP-S (n=33) and AVAPS-S (n=29), and between semi-recumbent and lateral positions in both modes. No difference was found in the length of hospital stay and the course of PaCO2, pH, and HCO3 levels between the modes. There was a mean reduction of 5.7±4.1 mmHg in the PaCO2 levels in the AVAPS-S mode, and 2.7±2.3 mmHg in the BiPAP-S mode per session (p<0.05). Obesity didn't have any effect on the course of PaCO2 in both the modes. Body positioning had no notable effect in both modes. Although the decrease in the PaCO2 levels in the AVAPS-S mode per session was remarkably high, the course was similar in both modes. Furthermore, obesity and body positioning had no prominent effect on the PaCO2 response and ventilator mechanics. Post hoc power analysis showed that the sample size was not adequate to detect a significant difference between the modes.

Impact of the systematic introduction of low-cost bubble nasal CPAP in a NICU of a developing country: a prospective pre- and post-intervention study.

PubMed

Rezzonico, Rossano; Caccamo, Letizia M; Manfredini, Valeria; Cartabia, Massimo; Sanchez, Nieves; Paredes, Zoraida; Froesch, Patrizia; Cavalli, Franco; Bonati, Maurizio

2015-03-25

The use of Nasal Continuous Positive Airway Pressure Ventilation (NCPAP) has begun to increase and is progressively replacing conventional mechanical ventilation (MV), becoming the cornerstone treatment for newborn respiratory distress syndrome (RDS). However, NCPAP use in Lower-Middle Income Countries (LMICs) is poor. Moreover, bubble NCPAP (bNCPAP), for efficacy, cost effectiveness, and ease of use, should be the primary assistance technique employed in newborns with RDS. To measure the impact on in-hospital newborn mortality of using a bNCPAP device as the first intervention on newborns requiring ventilatory assistance. Prospective pre-intervention and post-intervention study. The largest Neonatal Intensive Care Unit (NICU) in Nicaragua. In all, 230 (2006) and 383 (2008) patients were included. In May 2006, a strategy was introduced to promote the systematic use of bNCPAP to avoid intubation and MV in newborns requiring ventilatory assistance. Data regarding gestation, delivery, postnatal course, mortality, length of hospitalisation, and duration of ventilatory assistance were collected for infants assisted between May and December 2006, before the project began, and between May and December 2008, two years afterwards. The pre- vs post-intervention proportion of newborns who died in-hospital was the primary end point. Secondary endpoints included rate of intubation and duration of NICU stay. Significant differences were found in the rate of intubation (72 vs 39%; p < 0.0001) and the proportion of patients treated exclusively with bNCPAP (27% vs 61%; p <0.0001). Mortality rate was significantly reduced (40 vs 23%; p < 0.0001); however, an increase in the mean duration of NICU stay was observed (14.6 days in 2006 and 17.5 days in 2008, p = 0.0481). The findings contribute to the evidence that NCPAP, particularly bNCPAP, is the first-line standard of care for efficacy, cost effectiveness, and ease of use in newborns with respiratory distress in LMICs. This is the first extensive survey performed in a large NICU from a LMICs, proving the efficacy of the systematic use of a bNCPAP device in reducing newborn mortality. These findings are an incentive for considering bNCPAP as an elective strategy to treat newborns with respiratory insufficiency in LMICs.

[Pressure support ventilation and proportional assist ventilation during weaning from mechanical ventilation].

PubMed

Aguirre-Bermeo, H; Bottiroli, M; Italiano, S; Roche-Campo, F; Santos, J A; Alonso, M; Mancebo, J

2014-01-01

To compare tolerance, duration of mechanical ventilation (MV) and clinical outcomes during weaning from MV in patients subjected to either pressure support ventilation (PSV) or proportional assist ventilation (PAV). A prospective, observational study was carried out. Intensive Care Unit. A total of 40 consecutive subjects were allocated to either the PSV or the PAV group until each group contained 20 patients. Patients were included in the study when they met the criteria to begin weaning and the attending physician decided to initiate the weaning process. The physician selected the modality and set the ventilatory parameters. None. Demographic data, respiratory mechanics, ventilatory parameters, duration of MV, and clinical outcomes (reintubation, tracheostomy, mortality). Baseline characteristics were similar in both groups. No significant differences were observed between the PSV and PAV groups in terms of the total duration of MV (10 [5-18] vs. 9 [7-19] days; P=.85), reintubation (5 [31%] vs. 3 [19%]; P=.69), or mortality (4 [20%] vs. 5 [25%] deaths; P=1). Eight patients (40%) in the PSV group and 6 patients (30%) in the PAV group (P=.74) required a return to volume assist-control ventilation due to clinical deterioration. Tolerance, duration of MV and clinical outcomes during weaning from mechanical ventilation were similar in PSV and PAV. Copyright © 2013 Elsevier España, S.L. and SEMICYUC. All rights reserved.

[Spontaneous positive end-expiratory pressure ventilation in elderly patients with cardiogenic pulmonary edema. Assessment in an emergency admissions unit].

PubMed

L'Her, E; Duquesne, F; Paris, A; Mouline, J; Renault, A; Garo, B; Boles, J M

1998-06-20

Intubation and ventilatory assistance are often required in patients presenting severe hypoxemic respiratory distress, but may be contraindicated in elderly subjects due to an underlying condition. The aim of this study was to assess the feasibility, acceptability and contribution of early assistance with spontaneous positive end-expiratory pressure ventilation for elderly subjects admitted to an emergency unit for acute respiratory distress due to cardiogenic pulmonary edema. In our emergency admission unit, all patients with life-threatening hypoxemic respiratory distress are initially assisted with noninvasive spontaneous positive end-expiratory pressure ventilation using a standardized commercial device. We retrospectively analyzed the the files of all patients aged over 70 years who were treated with this standard protocol for cardiogenic pulmonary edema from April 1996 through September 1997. During the study period, 36 patients aged over 70 years required ventilatory assistance according to the standard protocol. Intubation was not reasonable in most of the patients (n = 30). After 1 hour of ventilation, none of the patients developed clinical signs of life-threatening distress. Blood gases demonstrated improved oxygenation (AEPO2 = +184.9 +/- 105.4 mmHg; p < 0.000001). Thirty-two patients were considered to be cured (88.9%) and were discharged; the cardiovascular condition was fatal in 4 patients (11.1%). The rapid improvement in clinical signs and blood gases as well as the final outcome suggests that early assistance with spontaneous positive end-expiratory pressure ventilation is warranted at admission for elderly patients with respiratory distress due to cardiogenic pulmonary edema. Compared with a control group of hospitalized patients cared for during the preceding year and who were not treated with the standard protocol, we also demonstrated a clear improvement in mortality (11% versus 20%).

[Domiciliary noninvasive positive pressure ventilation in chronic alveolar hypoventilation].

PubMed

Casas, J P; Robles, A M; Pereyra, M A; Abbona, H L; López, A M

2000-01-01

Effectiveness of treatment with domiciliary nocturnal noninvasive positive pressure ventilation is analyzed in a group of patients with chronic alveolar hypoventilation of different etiologies. It was applied with two levels of pressure (BiPAP) via nasal mask. Criteria for evaluation were symptomatology and improvement in gas exchange. Data were analyzed by Student t tests. A total of 13 patients were included, mean age 55.7 range 20 to 76 years (5 male 8 female). Main diagnosis was tuberculosis in 6, four of them having had surgical procedure (thoracoplasty 2, frenicectomy 1 and neumonectomy 1), myopathy 3 (myasthenia gravis 1, muscular dystrophy 1 and diaphragmatic paralysis 1), obesity-hypoventilation syndrome 1, escoliosis 1, bronchiectasis 1 and cystic fibrosis 1. These last two patients were on waiting list for lung transplantation. At the moment of consultation, the symptoms were: dysnea 13/13 (100%), astenia 13/13 (100%), hypersomnolency 10/13 (77%), cephalea 9/13 (69%), leg edema 6/13 (46%), loss of memory 6/13 (46%). Regarding gas exchange, they showed hypoxemia and hypercapnia. Mean follow up was of 2.2 years (range 6 months to 4 years). Within the year, all 13 patients became less dyspneic. Astenia, hypersomnolency, cephalea, leg edema and memory loss disappeared. Improvement in gas exchange was: PaO2/FiO2 from 269 +/- 65.4 (basal) to 336.7 +/- 75.3 post-treatment (p = 0.0018). PaCO2 from 70.77 +/- 25.48 mmHg (basal) to 46.77 +/- 8.14 mmHg (p = 0.0013). Ventilatory support was discontinued en 5 patients: three because of pneumonia requiring intubation and conventional mechanical ventilation, two of them died and one is still with tracheostomy; One patient with bronchiectasis and one with cystic fibrosis were transplanted. The remaining eight patients are stable. In conclusion, chronic alveolar hypoventilation can be effectively treated with domiciliary nocturnal noninvasive ventilation. Long term improvement in symptomatology and arterial blood gases can be obtained without significant complications.

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.

Airway pressure release ventilation: what do we know?

PubMed

Daoud, Ehab G; Farag, Hany L; Chatburn, Robert L

2012-02-01

Airway pressure release ventilation (APRV) is inverse ratio, pressure controlled, intermittent mandatory ventilation with unrestricted spontaneous breathing. It is based on the principle of open lung approach. It has many purported advantages over conventional ventilation, including alveolar recruitment, improved oxygenation, preservation of spontaneous breathing, improved hemodynamics, and potential lung-protective effects. It has many claimed disadvantages related to risks of volutrauma, increased work of breathing, and increased energy expenditure related to spontaneous breathing. APRV is used mainly as a rescue therapy for the difficult to oxygenate patients with acute respiratory distress syndrome (ARDS). There is confusion regarding this mode of ventilation, due to the different terminology used in the literature. APRV settings include the "P high," "T high," "P low," and "T low". Physicians and respiratory therapists should be aware of the different ways and the rationales for setting these variables on the ventilators. Also, they should be familiar with the differences between APRV, biphasic positive airway pressure (BIPAP), and other conventional and nonconventional modes of ventilation. There is no solid proof that APRV improves mortality; however, there are ongoing studies that may reveal further information about this mode of ventilation. This paper reviews the different methods proposed for APRV settings, and summarizes the different studies comparing APRV and BIPAP, and the potential benefits and pitfalls for APRV.

[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.

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

Bio-Inspired Controller on an FPGA Applied to Closed-Loop Diaphragmatic Stimulation

PubMed Central

Zbrzeski, Adeline; Bornat, Yannick; Hillen, Brian; Siu, Ricardo; Abbas, James; Jung, Ranu; Renaud, Sylvie

2016-01-01

Cervical spinal cord injury can disrupt connections between the brain respiratory network and the respiratory muscles which can lead to partial or complete loss of ventilatory control and require ventilatory assistance. Unlike current open-loop technology, a closed-loop diaphragmatic pacing system could overcome the drawbacks of manual titration as well as respond to changing ventilation requirements. We present an original bio-inspired assistive technology for real-time ventilation assistance, implemented in a digital configurable Field Programmable Gate Array (FPGA). The bio-inspired controller, which is a spiking neural network (SNN) inspired by the medullary respiratory network, is as robust as a classic controller while having a flexible, low-power and low-cost hardware design. The system was simulated in MATLAB with FPGA-specific constraints and tested with a computational model of rat breathing; the model reproduced experimentally collected respiratory data in eupneic animals. The open-loop version of the bio-inspired controller was implemented on the FPGA. Electrical test bench characterizations confirmed the system functionality. Open and closed-loop paradigm simulations were simulated to test the FPGA system real-time behavior using the rat computational model. The closed-loop system monitors breathing and changes in respiratory demands to drive diaphragmatic stimulation. The simulated results inform future acute animal experiments and constitute the first step toward the development of a neuromorphic, adaptive, compact, low-power, implantable device. The bio-inspired hardware design optimizes the FPGA resource and time costs while harnessing the computational power of spike-based neuromorphic hardware. Its real-time feature makes it suitable for in vivo applications. PMID:27378844

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.

[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.

Cerebrospinal fluid cytotoxicity does not affect survival in amyotrophic lateral sclerosis.

PubMed

Galán, L; Matías-Guiu, J; Matias-Guiu, J A; Yáñez, M; Pytel, V; Guerrero-Sola, A; Vela-Souto, A; Arranz-Tagarro, J A; Gómez-Pinedo, U; García, A G

2017-09-01

Cerebrospinal fluid (CSF) from some patients with amyotrophic lateral sclerosis (ALS) has been demonstrated to significantly reduce the neuronal viability of primary cell cultures of motor neurons. We aimed to study the potential clinical consequences associated with the cytotoxicity of CSF in a cohort of patients with ALS. We collected CSF from thirty-one patients with ALS. We analysed cytotoxicity by incubating it into the primary cultures of motor cortex neurons. Neural viability was quantified after 24 hours using the colorimetric MTT reduction assay. All patients were followed up from the moment of diagnosis to death, and a complete evaluation during disease progression and survival was performed, including gastrostomy and respiratory assistance. Twenty-one patients (67.7%) presented a cytotoxic CSF. There were no significant differences between patients with and without cytotoxicity regarding mean time from symptom onset to the diagnosis, from the diagnosis to death, from the diagnosis to respiratory assistance with BIPAP, from diagnosis to gastrostomy and from the onset of symptoms to death. In Cox regression analysis, bulbar onset, but not cytotoxicity, gender or age at onset, was associated with a lower risk of survival. Cerebrospinal fluid cytotoxicity was not associated with differential survival rates. This suggests that the presence of cytotoxicity in CSF, measured through neuronal viability in primary cultures of motor cortex neurons, could reflect different mechanisms of the disease, but it does not predict disease outcome. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

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

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

Clinical assessment of auto-positive end-expiratory pressure by diaphragmatic electrical activity during pressure support and neurally adjusted ventilatory assist.

PubMed

Bellani, Giacomo; Coppadoro, Andrea; Patroniti, Nicolò; Turella, Marta; Arrigoni Marocco, Stefano; Grasselli, Giacomo; Mauri, Tommaso; Pesenti, Antonio

2014-09-01

Auto-positive end-expiratory pressure (auto-PEEP) may substantially increase the inspiratory effort during assisted mechanical ventilation. Purpose of this study was to assess whether the electrical activity of the diaphragm (EAdi) signal can be reliably used to estimate auto-PEEP in patients undergoing pressure support ventilation and neurally adjusted ventilatory assist (NAVA) and whether NAVA was beneficial in comparison with pressure support ventilation in patients affected by auto-PEEP. In 10 patients with a clinical suspicion of auto-PEEP, the authors simultaneously recorded EAdi, airway, esophageal pressure, and flow during pressure support and NAVA, whereas external PEEP was increased from 2 to 14 cm H2O. Tracings were analyzed to measure apparent "dynamic" auto-PEEP (decrease in esophageal pressure to generate inspiratory flow), auto-EAdi (EAdi value at the onset of inspiratory flow), and IDEAdi (inspiratory delay between the onset of EAdi and the inspiratory flow). The pressure necessary to overcome auto-PEEP, auto-EAdi, and IDEAdi was significantly lower in NAVA as compared with pressure support ventilation, decreased with increase in external PEEP, although the effect of external PEEP was less pronounced in NAVA. Both auto-EAdi and IDEAdi were tightly correlated with auto-PEEP (r = 0.94 and r = 0.75, respectively). In the presence of auto-PEEP at lower external PEEP levels, NAVA was characterized by a characteristic shape of the airway pressure. In patients with auto-PEEP, NAVA, compared with pressure support ventilation, led to a decrease in the pressure necessary to overcome auto-PEEP, which could be reliably monitored by the electrical activity of the diaphragm before inspiratory flow onset (auto-EAdi).

Terminal weaning or immediate extubation for withdrawing mechanical ventilation in critically ill patients (the ARREVE observational study).

PubMed

Robert, René; Le Gouge, Amélie; Kentish-Barnes, Nancy; Cottereau, Alice; Giraudeau, Bruno; Adda, Mélanie; Annane, Djillali; Audibert, Juliette; Barbier, François; Bardou, Patrick; Bourcier, Simon; Bourenne, Jeremy; Boyer, Alexandre; Brenas, François; Das, Vincent; Desachy, Arnaud; Devaquet, Jérôme; Feissel, Marc; Ganster, Frédérique; Garrouste-Orgeas, Maïté; Grillet, Guillaume; Guisset, Olivier; Hamidfar-Roy, Rebecca; Hyacinthe, Anne-Claire; Jochmans, Sebastien; Jourdain, Mercé; Lautrette, Alexandre; Lerolle, Nicolas; Lesieur, Olivier; Lion, Fabien; Mateu, Philippe; Megarbane, Bruno; Merceron, Sybille; Mercier, Emmanuelle; Messika, Jonathan; Morin-Longuet, Paul; Philippon-Jouve, Bénédicte; Quenot, Jean-Pierre; Renault, Anne; Repesse, Xavier; Rigaud, Jean-Philippe; Robin, Ségolène; Roquilly, Antoine; Seguin, Amélie; Thevenin, Didier; Tirot, Patrice; Vinatier, Isabelle; Azoulay, Elie; Reignier, Jean

2017-12-01

The relative merits of immediate extubation versus terminal weaning for mechanical ventilation withdrawal are controversial, particularly regarding the experience of patients and relatives. This prospective observational multicentre study (ARREVE) was done in 43 French ICUs to compare terminal weaning and immediate extubation, as chosen by the ICU team. Terminal weaning was a gradual decrease in the amount of ventilatory assistance and immediate extubation was extubation without any previous decrease in ventilatory assistance. The primary outcome was posttraumatic stress symptoms (Impact of Event Scale Revised, IES-R) in relatives 3 months after the death. Secondary outcomes were complicated grief, anxiety, and depression symptoms in relatives; comfort of patients during the dying process; and job strain in staff. We enrolled 212 (85.5%) relatives of 248 patients with terminal weaning and 190 relatives (90.5%) of 210 patients with immediate extubation. Immediate extubation was associated with airway obstruction and a higher mean Behavioural Pain Scale score compared to terminal weaning. In relatives, IES-R scores after 3 months were not significantly different between groups (31.9 ± 18.1 versus 30.5 ± 16.2, respectively; adjusted difference, -1.9; 95% confidence interval, -5.9 to 2.1; p = 0.36); neither were there any differences in complicated grief, anxiety, or depression scores. Assistant nurses had lower job strain scores in the immediate extubation group. Compared to terminal weaning, immediate extubation was not associated with differences in psychological welfare of relatives when each method constituted standard practice in the ICU where it was applied. Patients had more airway obstruction and gasps with immediate extubation. ClinicalTrials.gov identifier: NCT01818895.

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.

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.

Robot-Assisted End-Effector-Based Stair Climbing for Cardiopulmonary Exercise Testing: Feasibility, Reliability, and Repeatability.

PubMed

Stoller, Oliver; Schindelholz, Matthias; Hunt, Kenneth J

2016-01-01

Neurological impairments can limit the implementation of conventional cardiopulmonary exercise testing (CPET) and cardiovascular training strategies. A promising approach to provoke cardiovascular stress while facilitating task-specific exercise in people with disabilities is feedback-controlled robot-assisted end-effector-based stair climbing (RASC). The aim of this study was to evaluate the feasibility, reliability, and repeatability of augmented RASC-based CPET in able-bodied subjects, with a view towards future research and applications in neurologically impaired populations. Twenty able-bodied subjects performed a familiarisation session and 2 consecutive incremental CPETs using augmented RASC. Outcome measures focussed on standard cardiopulmonary performance parameters and on accuracy of work rate tracking (RMSEP-root mean square error). Criteria for feasibility were cardiopulmonary responsiveness and technical implementation. Relative and absolute test-retest reliability were assessed by intraclass correlation coefficients (ICC), standard error of the measurement (SEM), and minimal detectable change (MDC). Mean differences, limits of agreement, and coefficients of variation (CoV) were estimated to assess repeatability. All criteria for feasibility were achieved. Mean V'O2peak was 106±9% of predicted V'O2max and mean HRpeak was 99±3% of predicted HRmax. 95% of the subjects achieved at least 1 criterion for V'O2max, and the detection of the sub-maximal ventilatory thresholds was successful (ventilatory anaerobic threshold 100%, respiratory compensation point 90% of the subjects). Excellent reliability was found for peak cardiopulmonary outcome measures (ICC ≥ 0.890, SEM ≤ 0.60%, MDC ≤ 1.67%). Repeatability for the primary outcomes was good (CoV ≤ 0.12). RASC-based CPET with feedback-guided exercise intensity demonstrated comparable or higher peak cardiopulmonary performance variables relative to predicted values, achieved the criteria for V'O2max, and allowed determination of sub-maximal ventilatory thresholds. The reliability and repeatability were found to be high. There is potential for augmented RASC to be used for exercise testing and prescription in populations with neurological impairments who would benefit from repetitive task-specific training.

Robot-Assisted End-Effector-Based Stair Climbing for Cardiopulmonary Exercise Testing: Feasibility, Reliability, and Repeatability

PubMed Central

Stoller, Oliver; Schindelholz, Matthias; Hunt, Kenneth J.

2016-01-01

Background Neurological impairments can limit the implementation of conventional cardiopulmonary exercise testing (CPET) and cardiovascular training strategies. A promising approach to provoke cardiovascular stress while facilitating task-specific exercise in people with disabilities is feedback-controlled robot-assisted end-effector-based stair climbing (RASC). The aim of this study was to evaluate the feasibility, reliability, and repeatability of augmented RASC-based CPET in able-bodied subjects, with a view towards future research and applications in neurologically impaired populations. Methods Twenty able-bodied subjects performed a familiarisation session and 2 consecutive incremental CPETs using augmented RASC. Outcome measures focussed on standard cardiopulmonary performance parameters and on accuracy of work rate tracking (RMSEP−root mean square error). Criteria for feasibility were cardiopulmonary responsiveness and technical implementation. Relative and absolute test-retest reliability were assessed by intraclass correlation coefficients (ICC), standard error of the measurement (SEM), and minimal detectable change (MDC). Mean differences, limits of agreement, and coefficients of variation (CoV) were estimated to assess repeatability. Results All criteria for feasibility were achieved. Mean V′O2peak was 106±9% of predicted V′O2max and mean HRpeak was 99±3% of predicted HRmax. 95% of the subjects achieved at least 1 criterion for V′O2max, and the detection of the sub-maximal ventilatory thresholds was successful (ventilatory anaerobic threshold 100%, respiratory compensation point 90% of the subjects). Excellent reliability was found for peak cardiopulmonary outcome measures (ICC ≥ 0.890, SEM ≤ 0.60%, MDC ≤ 1.67%). Repeatability for the primary outcomes was good (CoV ≤ 0.12). Conclusions RASC-based CPET with feedback-guided exercise intensity demonstrated comparable or higher peak cardiopulmonary performance variables relative to predicted values, achieved the criteria for V′O2max, and allowed determination of sub-maximal ventilatory thresholds. The reliability and repeatability were found to be high. There is potential for augmented RASC to be used for exercise testing and prescription in populations with neurological impairments who would benefit from repetitive task-specific training. PMID:26849137

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...

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...

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

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.

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

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.

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.

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.

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.

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.

Ultrasonography evaluation during the weaning process: the heart, the diaphragm, the pleura and the lung.

PubMed

Mayo, P; Volpicelli, G; Lerolle, N; Schreiber, A; Doelken, P; Vieillard-Baron, A

2016-07-01

On a regular basis, the intensivist encounters the patient who is difficult to wean from mechanical ventilatory support. The causes for failure to wean from mechanical ventilatory support are often multifactorial and involve a complex interplay between cardiac and pulmonary dysfunction. A potential application of point of care ultrasonography relates to its utility in the process of weaning the patient from mechanical ventilatory support. This article reviews some applications of ultrasonography that may be relevant to the process of weaning from mechanical ventilatory support. The authors have divided these applications of ultrasonography into four separate categories: the assessment of cardiac, diaphragmatic, and lung function; and the identification of pleural effusion; which can all be evaluated with ultrasonography during a dynamic process in which the intensivist is uniquely positioned to use ultrasonography at the point of care. Ultrasonography may have useful application during the weaning process from mechanical ventilatory support.

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

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

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

Neural breathing patterns in preterm newborns supported with non-invasive neurally adjusted ventilatory assist.

PubMed

García-Muñoz Rodrigo, Fermín; Urquía Martí, Lourdes; Galán Henríquez, Gloria; Rivero Rodríguez, Sonia; Hernández Gómez, Alberto

2018-06-18

To characterize the neural breathing pattern in preterm infants supported with non-invasive neurally adjusted ventilatory assist (NIV-NAVA). Single-center prospective observational study. The electrical activity of the diaphragm (EAdi) was periodically recorded in 30-second series with the Edi catheter and the Servo-n software (Maquet, Solna, Sweden) in preterm infants supported with NIV-NAVA. The EAdi Peak , EAdi Min , EAdi Tonic , EAdi Phasic , neural inspiratory, and expiratory times (nTi and nTe) and the neural respiratory rate (nRR) were calculated. EAdi curves were generated by Excel for visual examination and classified according to the predominant pattern. 291 observations were analyzed in 19 patients with a mean GA of 27.3 weeks (range 24-36 weeks), birth weight 1028 g (510-2945 g), and a median (IQR) postnatal age of 18 days (4-27 days). The distribution of respiratory patterns was phasic without tonic activity 61.9%, phasic with basal tonic activity 18.6, tonic burst 3.8%, central apnea 7.9%, and mixed pattern 7.9%. In addition, 12% of the records showed apneas of >10 seconds, and 50.2% one or more "sighs", defined as breaths with an EAdi Peak and/or nTi greater than twice the average EAdi Peak and/or nTi of the recording. Neural times were measurable in 252 observations. The nTi was, median (IQR): 279 ms (253-285 ms), the nTe 764 ms (642-925 ms), and the nRR 63 bpm (51-70), with a great intra and inter-subjects variability. The neural breathing patterns in preterm infants supported with NIV-NAVA are quite variable and are characterized by the presence of significant tonic activity. Central apneas and sighs are common in this group of patients. The nTi seems to be shorter than the mechanical Ti commonly used in assisted ventilation.

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.

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

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.

Tracheal Injuries Complicating Prolonged Intubation and Tracheostomy.

PubMed

Cooper, Joel D

2018-05-01

Respiratory care advances such as the introduction of ventilatory assistance have been associated with postintubation airway stenosis resulting from tracheal injury at the site of the inflatable cuff on endotracheal or tracheostomy tubes. Low-pressure cuffs have significantly reduced this occurrence. Loss of airway stability at the site of a tracheostomy stoma may result in tracheal stenosis. Subglottic stenosis may result from a high tracheostomy site at, or just inferior to, the cricoid arch, or to malposition of an endotracheal tube cuff. Awareness of these complications and their causes is essential to prevent their occurrence. Copyright © 2018 Elsevier Inc. All rights reserved.

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.

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.

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

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.

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.

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.

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.

USE OF POSITIVE PRESSURE IN THE BARIATRIC SURGERY AND EFFECTS ON PULMONARY FUNCTION AND PREVALENCE OF ATELECTASIS: RANDOMIZED AND BLINDED CLINICAL TRIAL

PubMed Central

BALTIERI, Letícia; SANTOS, Laisa Antonela; RASERA-JUNIOR, Irineu; MONTEBELO, Maria Imaculada Lima; PAZZIANOTTO-FORTI, Eli Maria

2014-01-01

Background In surgical procedures, obesity is a risk factor for the onset of intra and postoperative respiratory complications. Aim Determine what moment of application of positive pressure brings better benefits on lung function, incidence of atelectasis and diaphragmatic excursion, in the preoperative, intraoperative or immediate postoperative period. Method Randomized, controlled, blinded study, conducted in a hospital and included subjects with BMI between 40 and 55 kg/m2, 25 and 55 years, underwent bariatric surgery by laparotomy. They were underwent preoperative and postoperative evaluations. They were allocated into four different groups: 1) Gpre: treated with positive pressure in the BiPAP mode (Bi-Level Positive Airway Pressure) before surgery for one hour; 2) Gpos: BIPAP after surgery for one hour; 3) Gintra: PEEP (Positive End Expiratory Pressure) at 10 cmH2O during the surgery; 4) Gcontrol: only conventional respiratory physiotherapy. The evaluation consisted of anthropometric data, pulmonary function tests and chest radiography. Results Were allocated 40 patients, 10 in each group. There were significant differences for the expiratory reserve volume and percentage of the predicted expiratory reserve volume, in which the groups that received treatment showed a smaller loss in expiratory reserve volume from the preoperative to postoperative stages. The postoperative radiographic analysis showed a 25% prevalence of atelectasis for Gcontrol, 11.1% for Gintra, 10% for Gpre, and 0% for Gpos. There was no significant difference in diaphragmatic mobility amongst the groups. Conclusion The optimal time of application of positive pressure is in the immediate postoperative period, immediately after extubation, because it reduces the incidence of atelectasis and there is reduction of loss of expiratory reserve volume. PMID:25409961

Use of positive pressure in the bariatric surgery and effects on pulmonary function and prevalence of atelectasis: randomized and blinded clinical trial.

PubMed

Baltieri, Letícia; Santos, Laisa Antonela; Rasera, Irineu; Montebelo, Maria Imaculada Lima; Pazzianotto-Forti, Eli Maria

2014-01-01

In surgical procedures, obesity is a risk factor for the onset of intra and postoperative respiratory complications. Determine what moment of application of positive pressure brings better benefits on lung function, incidence of atelectasis and diaphragmatic excursion, in the preoperative, intraoperative or immediate postoperative period. Randomized, controlled, blinded study, conducted in a hospital and included subjects with BMI between 40 and 55 kg/m2, 25 and 55 years, underwent bariatric surgery by laparotomy. They were underwent preoperative and postoperative evaluations. They were allocated into four different groups: 1) Gpre: treated with positive pressure in the BiPAP mode (Bi-Level Positive Airway Pressure) before surgery for one hour; 2) Gpos: BIPAP after surgery for one hour; 3) Gintra: PEEP (Positive End Expiratory Pressure) at 10 cmH2O during the surgery; 4) Gcontrol: only conventional respiratory physiotherapy. The evaluation consisted of anthropometric data, pulmonary function tests and chest radiography. Were allocated 40 patients, 10 in each group. There were significant differences for the expiratory reserve volume and percentage of the predicted expiratory reserve volume, in which the groups that received treatment showed a smaller loss in expiratory reserve volume from the preoperative to postoperative stages. The postoperative radiographic analysis showed a 25% prevalence of atelectasis for Gcontrol, 11.1% for Gintra, 10% for Gpre, and 0% for Gpos. There was no significant difference in diaphragmatic mobility amongst the groups. The optimal time of application of positive pressure is in the immediate postoperative period, immediately after extubation, because it reduces the incidence of atelectasis and there is reduction of loss of expiratory reserve volume.

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 CO₂ GAP Project--CO₂ GAP as a prognostic tool in emergency departments.

PubMed

Shetty, Amith L; Lai, Kevin H; Byth, Karen

2010-12-01

To determine whether CO₂ GAP [(a-ET) PCO₂] value differs consistently in patients presenting with shortness of breath to the ED requiring ventilatory support. To determine a cut-off value of CO₂ GAP, which is consistently associated with measured outcome and to compare its performance against other derived variables. This prospective observational study was conducted in ED on a convenience sample of 412 from 759 patients who underwent concurrent arterial blood gas and ETCO₂ (end-tidal CO₂) measurement. They were randomized to test sample of 312 patients and validation set of 100 patients. The primary outcome of interest was the need for ventilatory support and secondary outcomes were admission to high dependency unit or death during stay in ED. The randomly selected training set was used to select cut-points for the possible predictors; that is, CO₂ GAP, CO₂ gradient, physiologic dead space and A-a gradient. The sensitivity, specificity and predictive values of these predictors were validated in the test set of 100 patients.   Analysis of the receiver operating characteristic curves revealed the CO₂ GAP performed significantly better than the arterial-alveolar gradient in patients requiring ventilator support (area under the curve 0.950 vs 0.726). A CO₂ GAP ≥10 was associated with assisted ventilation outcomes when applied to the validation test set (100% sensitivity 70% specificity). The CO₂ GAP [(a-ET) PCO₂] differs significantly in patients requiring assisted ventilation when presenting with shortness of breath to EDs and further research addressing the prognostic value of CO₂ GAP in this specific aspect is required. © 2010 The Authors. EMA © 2010 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

Neurally Adjusted Ventilatory Assist After Pediatric Cardiac Surgery: Clinical Experience and Impact on Ventilation Pressures.

PubMed

Crulli, Benjamin; Khebir, Mariam; Toledano, Baruch; Vobecky, Suzanne; Poirier, Nancy; Emeriaud, Guillaume

2018-02-01

After pediatric cardiac surgery, ventilation with high airway pressures can be detrimental to right ventricular function and pulmonary blood flow. Neurally adjusted ventilatory assist (NAVA) improves patient-ventilator interactions, helping maintain spontaneous ventilation. This study reports our experience with the use of NAVA in children after a cardiac surgery. We hypothesize that using NAVA in this population is feasible and allows for lower ventilation pressures. We retrospectively studied all children ventilated with NAVA (invasively or noninvasively) after undergoing cardiac surgery between January 2013 and May 2015 in our pediatric intensive care unit. The number and duration of NAVA episodes were described. For the first period of invasive NAVA in each subject, detailed clinical and ventilator data in the 4 h before and after the start of NAVA were extracted. 33 postoperative courses were included in 28 subjects with a median age of 3 [interquartile range (IQR) 1-12] months. NAVA was used invasively in 27 courses for a total duration of 87 (IQR 15-334) h per course. Peak inspiratory pressures and mean airway pressures decreased significantly after the start of NAVA (mean differences of 5.8 cm H 2 O (95% CI 4.1-7.5) and 2.0 cm H 2 O (95% CI 1.2-2.8), respectively, P < .001 for both). There was no significant difference in vital signs or blood gas values. NAVA was used noninvasively in 14 subjects, over 79 (IQR 25-137) h. NAVA could be used in pediatric subjects after cardiac surgery. The significant decrease in airway pressures observed after transition to NAVA could have a beneficial impact in this specific population, which should be investigated in future interventional studies. Copyright © 2018 by Daedalus Enterprises.

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.

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

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.

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

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.

A field study of the ventilatory response to ambient temperature and pressure in sport diving.

PubMed Central

Muller, F L

1995-01-01

This study reports on the relationship between minute ventilation (VE) and environmental variables of temperature (T) and pressure (P) during open water diving. The author conducted a total of 38 dives involving either a light (20 dives) or a moderate (18 dives) level of physical activity. Within each of these groups, P and T taken together accounted for about two thirds of the variance in the VE data. A very significant increase in VE was observed as T decreased (1 < T(degrees C) < 22), and the magnitude of this increase at a given pressure level was similar in the 'light' and the 'moderate' data sets. A second order observation, particularly notable at lower temperature, was the decrease in VE with increasing pressure under conditions of light work. Empirical functions of the from VE = A+B/P n[1 + exp(T - 8)/10], where A, B, and n are adjustable variables, could accommodate both data sets over the whole range of T and P. These results are the first obtained under actual diving conditions to provide evidence for interactions between P, T, and VE. Understanding the physiological mechanisms by which these interactions occur would assist in appreciation of the limitations imposed on scuba divers by the environmental conditions as they affect their ventilatory responses. PMID:8800853

Proportional mechanical ventilation through PWM driven on/off solenoid valve.

PubMed

Sardellitti, I; Cecchini, S; Silvestri, S; Caldwell, D G

2010-01-01

Proportional strategies for artificial ventilation are the most recent form of synchronized partial ventilatory assistance and intra-breath control techniques available in clinical practice. Currently, the majority of commercial ventilators allowing proportional ventilation uses proportional valves to generate the flow rate pattern. This paper proposes on-off solenoid valves for proportional ventilation given their small size, low cost and short switching time, useful for supplying high frequency ventilation. A new system based on a novel fast switching driver circuit combined with on/off solenoid valve is developed. The average short response time typical of onoff solenoid valves was further reduced through the driving circuit for the implementation of PWM control. Experimental trials were conducted for identifying the dynamic response of the PWM driven on/off valve and for verifying its effectiveness in generating variable-shaped ventilatory flow rate patterns. The system was able to smoothly follow the reference flow rate patterns also changing in time intervals as short as 20 ms, achieving a flow rate resolution up to 1 L/min and repeatability in the order of 0.5 L/min. Preliminary results showed the feasibility of developing a stand alone portable device able to generate both proportional and high frequency ventilation by only using on-off solenoid valves.

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.

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.

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.

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.

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

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.

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.

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.

Video-assisted thoracoscopy for diaphragmatic plication: experimental study in a canine model.

PubMed

Gonzalez-Zamora, Jose F; Perez-Guille, Beatriz; Soriano-Rosales, Rosa E; Jimenez-Bravo-Luna, Miguel A; Gutierrez-Castrellon, Pedro; Ridaura-Sanz, Cecilia; Alvarez, Fernando Villegas

2005-12-01

Plication of a nonfunctional hemidiaphragm usually restores altered ventilatory mechanics. This study compared two techniques in performing diaphragmatic plication: video-assisted thoracoscopy (group A) and thoracotomy (group B). Twenty dogs with induced paralysis of the right hemidiaphragm were randomly assigned to one of the two groups. Evaluations were performed before and after plication of the respiratory frequency (f) and lung area (LA) of the affected side. Operative time, time to resumption of walking, ingestion of fluids and solid food, pain intensity, and postoperative complications were measured. Group A had less pain after the surgery (P < 0.0001), earlier fluid ingestion (P < 0.05), and earlier resumption of walking (P < 0.019). Four weeks after the procedure, LA was similar in both groups, while a significant decrease in f was recorded in group A (P < 0.02). The remaining evaluated variables showed no differences. Both approaches were effective. Pain recorded in the postoperative period was less and recovery was faster in group A. Complications and surgical times were similar. The video-assisted thoracoscopy is a safe and efficient option for performing diaphragmatic plication in dogs.

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.

Functional significance and control of release of pulmonary surfactant in the lizard lung.

PubMed

Wood, P G; Daniels, C B; Orgeig, S

1995-10-01

The amount of pulmonary surfactant in the lungs of the bearded dragon (Pogona vitticeps) increases with increasing body temperature. This increase coincides with a decrease in lung compliance. The relationship between surfactant and lung compliance and the principal stimuli for surfactant release and composition (temperature, ventilatory pattern, and autonomic neurotransmitters) were investigated. We chose to investigate ventilatory pattern (which causes mechanical deformation of the type II cells) and adrenergic agents, because they are the major stimuli for surfactant release in mammals. To examine the effects of body temperature and ventilatory pattern, isolated lungs were ventilated at either 18 or 37 degrees C at different ventilatory regimens. An isolated perfused lung preparation at 27 degrees C was used to analyze the effects of autonomic neurotransmitters. Ventilatory pattern did not affect surfactant release, composition, or lung compliance at either 18 or 37 degrees C. An increase in temperature increased phospholipid reuptake and disproportionately increased cholesterol degradation/uptake. Epinephrine and acetylcholine stimulated phospholipid but not cholesterol release. Removal of surfactant caused a decrease in compliance, regardless of the experimental temperature. Temperature appears to be the principal determinant of lung compliance in the bearded dragon, acting directly to increase the tone of the smooth muscle. Increasing the ambient temperature may result in greater surfactant turnover by increasing cholesterol reuptake/degradation directly and by increasing circulating epinephrine, thereby indirectly increasing phospholipid secretion. We suggest that changing ventilatory pattern may be inadequate as a mechanism for maintaining surfactant homeostasis, given the discontinuous, highly variable reptilian breathing pattern.

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.

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

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.

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.

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

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.

[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.

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

[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.

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.

Congenital central hypoventilation syndrome: diagnostic and management challenges.

PubMed

Kasi, Ajay S; Perez, Iris A; Kun, Sheila S; Keens, Thomas G

2016-01-01

Congenital central hypoventilation syndrome (CCHS) is a rare genetic disorder with failure of central control of breathing and of the autonomic nervous system function due to a mutation in the paired-like homeobox 2B (PHOX2B) gene. Affected patients have absent or negligible ventilatory sensitivity to hypercapnia and hypoxemia, and they do not exhibit signs of respiratory distress when challenged with hypercarbia or hypoxia. The diagnosis of CCHS must be confirmed with PHOX2B gene mutation. Generally, the PHOX2B mutation genotype can aid in anticipating the severity of the phenotype. They require ventilatory support for life. Home assisted ventilation options include positive pressure ventilation via tracheostomy, noninvasive positive pressure ventilation, and diaphragm pacing via phrenic nerve stimulation, but each strategy has its associated limitations and challenges. Since all the clinical manifestations of CCHS may not manifest at birth, periodic monitoring and early intervention are necessary to prevent complications and improve outcome. Life-threatening arrhythmias can manifest at different ages and a normal cardiac monitoring study does not exclude future occurrences leading to the dilemma of timing and frequency of cardiac rhythm monitoring and treatment. Given the rare incidence of CCHS, most health care professionals are not experienced with managing CCHS patients, particularly those with diaphragm pacers. With early diagnosis and advances in home mechanical ventilation and monitoring strategies, many CCHS children are surviving into adulthood presenting new challenges in their care.

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.

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.

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.

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

Incentive spirometry for preventing pulmonary complications after coronary artery bypass graft.

PubMed

Freitas, E R F S; Soares, B G O; Cardoso, J R; Atallah, A N

2007-07-18

Following coronary artery bypass graft (CABG), the main causes of postoperative morbidity and mortality are postoperative pulmonary complications, respiratory dysfunction and arterial hypoxemia. Incentive spirometry is a treatment technique that uses a mechanical device (an incentive spirometer) to reduce such pulmonary complications during postoperative care. To assess the effects of incentive spirometry for preventing postoperative pulmonary complications in adults undergoing CABG. We searched CENTRAL on The Cochrane Library (Issue 2, 2004), MEDLINE (1966 to December 2004), EMBASE (1980 to December 2004), LILACS (1982 to December 2004), the Physiotherapy Evidence Database (PEDro) (1980 to December 2004), Allied & Complementary Medicine (AMED) (1985 to December 2004), CINAHL (1982 to December 2004), and the Database of Abstracts of Reviews of Effects (DARE) (1994 to December 2004). References were checked and authors contacted. No language restrictions were applied. Randomized controlled trials comparing incentive spirometry with any type of prophylactic physiotherapy for prevention of postoperative pulmonary complications in adults undergoing CABG. Two reviewers independently evaluated the quality of trials using the guidelines of the Cochrane Reviewers' Handbook and extracted data from included trials. Four trials with 443 participants contributed to this review. There was no significant difference in pulmonary complications (atelectasis and pneumonia) between treatment with incentive spirometry and treatment with positive pressure breathing techniques (continuous positive airway pressure (CPAP), bilevel positive airway pressure (BiPAP) and intermittent positive pressure breathing (IPPB)) or preoperative patient education. Patients treated with incentive spirometry had worse pulmonary function and arterial oxygenation compared with positive pressure breathing (CPAP, BiPAP, IPPB). Individual small trials suggest that there is no evidence of benefit from incentive spirometry in reducing pulmonary complications and in decreasing the negative effects on pulmonary function in patients undergoing CABG. In view of the modest number of patients studied, methodological shortcomings and poor reporting of the included trials, these results should be interpreted cautiously. An appropriately powered trial of high methodological rigour is needed to determine those patients who may derive benefit from incentive spirometry following CABG.

Selective indication for positive airway pressure (PAP) in sleep-related breathing disorders with obstruction

PubMed Central

Stasche, Norbert

2006-01-01

Positive airway pressure (PAP) is the therapy of choice for most sleep-related breathing disorders (SRBD). A variety of PAP devices using positive airway pressure (CPAP, BiPAP, APAP, ASV) must be carefully considered before application. This overview aims to provide criteria for choosing the optimal PAP device according to severity and type of sleep-related breathing disorder. In addition, the range of therapeutic applications, constraints and side effects as well as alternative methods to PAP will be discussed. This review is based on an analysis of current literature and clinical experience. The data is presented from an ENT-sleep-laboratory perspective and is designed to help the ENT practitioner initiate treatment and provide support. Different titration methods, current devices and possible applications will be described. In addition to constant pressure devices (CPAP), most commonly used for symptomatic obstructive sleep apnoea (OSA) without complicating conditions, BiPAP models will be introduced. These allow two different positive pressure settings and are thus especially suitable for patients with cardiopulmonary diseases or patients with pressure intolerance, increasing compliance in this subgroup considerably. Compliance can also be increased in patients during first night of therapy, patients with highly variable pressure demands or position-dependent OSA, by using self-regulating Auto-adjust PAP devices (Automatic positive airway pressure, APAP). Patients with Cheyne-Stokes breathing, a subtype of central sleep apnoea, benefit from adaptive servo-ventilation (ASV), which analyzes breathing patterns continually and adjusts the actual ventilation pressure accordingly. This not only reduces daytime sleepiness, but can also influence heart disease positively. Therapy with positive airway pressure is very effective in eliminating obstruction-related sleep diseases and symptoms. However, because therapy is generally applied for life, the optimal PAP device must be carefully selected, taking into account side effects that influence compliance. PMID:22073075

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.

[Lung protective ventilation. Ventilatory modes and ventilator parameters].

PubMed

Schädler, Dirk; Weiler, Norbert

2008-06-01

Mechanical ventilation has a considerable potential for injuring the lung tissue. Therefore, attention has to be paid to the proper choice of ventilatory mode and settings to secure lung-protective ventilation whenever possible. Such ventilator strategy should account for low tidal volume ventilation (6 ml/kg PBW), limited plateau pressure (30 to 35 cm H2O) and positive end-expiratory pressure (PEEP). It is unclear whether pressure controlled or volume controlled ventilation with square flow profile is beneficial. The adjustment of inspiration and expiration time should consider the actual breathing mechanics and anticipate the generation of intrinsic PEEP. Ventilatory modes with the possibility of supporting spontaneous breathing should be used as soon as possible.

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...

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.

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.

Emphysema on Thoracic CT and Exercise Ventilatory Inefficiency in Mild-to-Moderate COPD.

PubMed

Jones, Joshua H; Zelt, Joel T; Hirai, Daniel M; Diniz, Camilla V; Zaza, Aida; O'Donnell, Denis E; Neder, J Alberto

2017-04-01

There is growing evidence that emphysema on thoracic computed tomography (CT) is associated with poor exercise tolerance in COPD patients with only mild-to-moderate airflow obstruction. We hypothesized that an excessive ventilatory response to exercise (ventilatory inefficiency) would underlie these abnormalities. In a prospective study, 19 patients (FEV 1 = 82 ± 13%, 12 Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 1) and 26 controls underwent an incremental exercise test. Ventilatory inefficiency was assessed by the ventilation ([Formula: see text]E)/CO 2 output ([Formula: see text]CO 2 ) nadir. Pulmonary blood flow (PBF) in a submaximal test was calculated by inert gas rebreathing. Emphysema was quantified as % of attenuation areas below 950 HU. Patients typically presented with centrilobular emphysema (76.8 ± 10.1% of total emphysema) in the upper lobes (upper/total lung ratio = 0.82 ± 0.04). They had lower peak oxygen uptake ([Formula: see text]O 2 ), higher [Formula: see text]E/[Formula: see text]CO 2 nadir, and greater dyspnea scores than controls (p < 0.05). Lower peak [Formula: see text]O 2 and worse dyspnea were found in patients with higher [Formula: see text]E/[Formula: see text]CO 2 nadirs (≥30). Patients had blunted increases in PBF from rest to iso-[Formula: see text]O 2 exercise (p < 0.05). Higher [Formula: see text]E/[Formula: see text]CO 2 nadir in COPD was associated with emphysema severity (r = 0.63) which, in turn, was related to reduced lung diffusing capacity (r = -0.72) and blunted changes in PBF from rest to exercise (r = -0.69) (p < 0.01). Ventilation "wasted" in emphysematous areas is associated with impaired exercise ventilatory efficiency in mild-to-moderate COPD. Exercise ventilatory inefficiency links structure (emphysema) and function (D L CO) to a key clinical outcome (poor exercise tolerance) in COPD patients with only modest spirometric abnormalities.

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.

A Tool for Music Preference Assessment in Critically Ill Patients Receiving Mechanical Ventilatory Support

PubMed Central

CHLAN, LINDA; HEIDERSCHEIT, ANNIE

2010-01-01

Music is an ideal intervention to reduce anxiety and promote relaxation in critically ill patients. This article reviews the research studies on music-listening interventions to manage distressful symptoms in this population, and describes the development and implementation of the Music Assessment Tool (MAT) to assist professionals in ascertaining patients’ music preferences in the challenging, dynamic clinical environment of the intensive care unit (ICU). The MAT is easy to use with these patients who experience profound communication challenges due to fatigue and inability to speak because of endotracheal tube placement. The music therapist and ICU nursing staff are encouraged to work collaboratively to implement music in a personalized manner to ensure the greatest benefit for mechanically ventilated patients. PMID:24489432

Lvad pump speed increase is associated with increased peak exercise cardiac output and vo2, postponed anaerobic threshold and improved ventilatory efficiency.

PubMed

Vignati, Carlo; Apostolo, Anna; Cattadori, Gaia; Farina, Stefania; Del Torto, Alberico; Scuri, Silvia; Gerosa, Gino; Bottio, Tomaso; Tarzia, Vincenzo; Bejko, Jonida; Sisillo, Erminio; Nicoli, Flavia; Sciomer, Susanna; Alamanni, Francesco; Paolillo, Stefania; Agostoni, Piergiuseppe

2017-03-01

Peak exercise cardiac output (CO) increase is associated with an increase of peak oxygen uptake (VO 2 ), provided that arteriovenous O 2 difference [Δ(Ca-Cv)O 2 ] does not decrease. At anaerobic threshold, VO 2 , is related to CO. We tested the hypothesis that, in heart failure (HF) patients with left ventricular assistance device (LVAD), an acute increase of CO obtained through changes in LVAD pump speed is associated with peak exercise and anaerobic threshold VO 2 increase. Fifteen of 20 patients bearing LVAD (Jarvik 2000) enrolled in the study successfully performed peak exercise evaluation. All patients had severe HF as shown by clinical evaluation, laboratory tests, echocardiography, spirometry with alveolar-capillary diffusion, and maximal cardiopulmonary exercise testing (CPET). CPETs with non-invasive CO measurements at rest and peak exercise were done on 2days at LVAD pump speed set randomly at 2 and 4. Increasing LVAD pump speed from 2 to 4 increased CO from 3.4±0.9 to 3.8±1.0L/min (ΔCO 0.4±0.6L/min, p=0.04) and from 5.3±1.3 to 5.9±1.4L/min (ΔCO 0.6±0.7L/min, p<0.01) at rest and peak exercise, respectively. Similarly, VO 2 increased from 788±169 to 841±152mL/min (ΔVO 2 52±76mL/min, p=0.01) and from 568±116 to 619±124mL/min (ΔVO 2 69±96mL/min, p=0.02) at peak exercise and at anaerobic threshold, respectively. Δ(Ca-Cv)O 2 did not change significantly, while ventilatory efficiency improved (VE/VCO 2 slope from 39.9±5.4 to 34.9±8.3, ΔVE/VCO 2 -5.0±6.4, p<0.01). In HF, an increase in CO with a higher LVAD pump speed is associated with increased peak VO 2 , postponed anaerobic threshold, and improved ventilatory efficiency. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Respiratory gas conditioning in infants with an artificial airway.

PubMed

Schulze, Andreas

2002-10-01

There is a strong physiological rationale for delivering the inspiratory gas at or close to core body temperature and saturated with water vapour to infants with an artificial airway undergoing long-term mechanical ventilatory assistance. Cascade humidifiers with heated wire ventilatory circuitry may achieve this goal safely. Whenever saturated air leaves the humidifier chamber at 37 degrees C and condensate accumulates in the circuit, the gas loses humidity and acquires the potential to dry airway secretions near the tip of the endotracheal tube. Heat and moisture exchangers and hygroscopic condenser humidifiers with or without bacterial filters have become available for neonates. They can provide sufficient moisture output for short-term ventilation without excessive additional dead space or flow-resistive load for term infants. Their safety and efficacy for very low birthweight infants and for long-term mechanical ventilation has not been established conclusively. A broader application of these inexpensive and simple devices is likely to occur with further design improvements. When heated humidifiers are appropriately applied, water or normal saline aerosol application offers no additional significant advantage in terms of inspiratory gas conditioning and may impose a water overload on the airway or even systemically. Although airway irrigation by periodic bolus instillation of normal saline solution prior to suctioning procedures is widely practised in neonatology, virtually no data exist on its safety and efficacy when used with appropriately humidified inspired gas. There is no evidence that conditioning of inspired gas to core body temperature and full water vapour saturation may promote nosocomial respiratory infections.

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.

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.

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...

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.

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.

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.

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.

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

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.

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.

Pulmonary function test findings in patients with acute inhalation injury caused by smoke bombs

PubMed Central

Cao, Lu; Zhang, Xin-Gang; Wang, Jian-Guo; Wang, Han-Bin; Chen, Yi-Bing; Zhao, Da-Hui; Shi, Wen-Fang

2016-01-01

Background This study aimed to determine the effects of smoke bomb-induced acute inhalation injury on pulmonary function at different stages of lung injury. Methods We performed pulmonary function tests (PFTs) in 15 patients with acute inhalation injury from days 3 to 180 after smoke inhalation. We measured the trace element zinc in whole blood on days 4 and 17, and correlations of zinc levels with PFTs were performed. Results In the acute stage of lung injury (day 3), 3 of 11 patients with mild symptoms had normal pulmonary function and 8 patients with restrictive ventilatory dysfunction and reduced diffusing capacity. Some patients also had mild obstructive ventilatory dysfunction (5 patients) and a decline in small airway function (6 patients). For patients with severe symptoms, PFT results showed moderate to severe restrictive ventilatory dysfunction and reduced diffusing capacity. PaCO2 was significantly higher (P=0.047) in patients with reduced small airway function compared with those with normal small airway function. Whole blood zinc levels in the convalescence stage (day 17) were significantly lower than those in the acute stage (day 4). Zinc in the acute stage was negatively correlated with DLCO/VA on days 3, 10, and 46 (r=−0.633, −0.676, and −0.675 respectively, P<0.05). Conclusions Smoke inhalation injury mainly causes restrictive ventilatory dysfunction and reduced diffusing capacity, and causes mild obstructive ventilatory dysfunction and small airway function decline in some patients. Zinc is negatively correlated with DLCO/VA. Zinc levels may be able to predict prognosis and indicate the degree of lung injury. PMID:28066595

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.

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)

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.

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

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

[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.

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

[Spinal muscular atrophy and respiratory failure. How do primary care pediatricians act in a simulated scenario?].

PubMed

Agra Tuñas, M C; Sánchez Santos, L; Busto Cuiñas, M; Rodríguez Núñez, A

2015-11-01

Spinal muscular atrophy type 1 (SMA-1) tends to be fatal in the first year of life if there is no ventilatory support. The decision whether to start such support is an ethical conflict for healthcare professionals. A scenario of acute respiratory failure in an infant with SMA-1 has been included in a training program using advanced simulation for Primary Care pediatricians (PCP). The performances of 34 groups of 4 pediatricians, who participated in 17 courses, were systematically analyzed. Clinical, ethical and communication aspects with parents were evaluated. The initial technical assistance (Administration of oxygen and immediate ventilatory support) was correctly performed by 94% of the teams. However, the PCP had problems in dealing with the ethical aspects of the case. Of the 85% of the teams that raised the ethical conflict with parents, 29% did so on their own initiative, 23% actively excluded them, and only 6% involved them and took their opinion into account in making decisions. Only 11.7% asked about the quality of life of children and 12% for their knowledge of the prognosis of the disease. None explained treatment alternatives, nor tried to contact the pediatrician responsible for the child. When faced with a simulated SMA-1 infant with respiratory failure, PCP have difficulties in interacting with the family, and to involve it in the decision making process. Practical training of all pediatricians should include case scenarios with an ethical clinical problem. Copyright © 2014 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.

Regular tracheostomy tube changes to prevent formation of granulation tissue.

PubMed

Yaremchuk, Kathleen

2003-01-01

Tracheostomy is a commonly performed operative procedure that has been described since 2000 B.C. The early indications for tracheostomy were for upper airway obstruction, usually occurring in young people as a result of an infectious process. Recently, tracheostomies are more commonly performed in the critically ill patient to assist in long-term ventilatory support. Granulation tissue at the stoma and the trachea has been described as a late complication resulting in bleeding, drainage, and difficulty with maintaining mechanical ventilatory support. The present report is of an observational study of a newly implemented policy that required regular changing of tracheostomy tubes. Comparable groups of patients were compared before and after this procedural change to document complications. Data collection consisted of chart reviews of all admissions for 1 year before the policy change and the subsequent 2 years. Complication rates were compared using standard statistical techniques. A policy change was instituted that required all tracheostomy tubes to be changed every 2 weeks in conjunction with a detailed evaluation of the tracheostomy stoma. Charts were reviewed the year before the change in policy and in the subsequent 2 years to determine the incidence of granulation tissue requiring operative intervention. The number of patients requiring surgical intervention secondary to granulation tissue showed a statistically significant decrease (P =.02). A review of policies and procedures from the six largest hospitals in southeastern Michigan had no recommendations for routine tracheostomy tube changes. A policy requiring a routine change of tracheostomy tubes results in fewer complications from granulation tissue. Tracheostomy tube changes to prevent granulation tissue and its complications.

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

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.

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.

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.

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.

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.

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.

[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.

[Neuromuscular disease: respiratory clinical assessment and follow-up].

PubMed

Martínez Carrasco, C; Villa Asensi, J R; Luna Paredes, M C; Osona Rodríguez de Torres, F B; Peña Zarza, J A; Larramona Carrera, H; Costa Colomer, J

2014-10-01

Patients with neuromuscular disease are an important group at risk of frequently suffering acute or chronic respiratory failure, which is their main cause of death. They require follow-up by a pediatric respiratory medicine specialist from birth or diagnosis in order to confirm the diagnosis and treat any respiratory complications within a multidisciplinary context. The ventilatory support and the cough assistance have improved the quality of life and long-term survival for many of these patients. In this paper, the authors review the pathophysiology, respiratory function evaluation, sleep disorders, and the most frequent respiratory complications in neuromuscular diseases. The various treatments used, from a respiratory medicine point of view, will be analyzed in a next paper. Copyright © 2013 Asociación Española de Pediatría. Published by Elsevier Espana. All rights reserved.

Noninvasive ventilation.

PubMed

Rabatin, J T; Gay, P C

1999-08-01

Noninvasive ventilation refers to the delivery of assisted ventilatory support without the use of an endotracheal tube. Noninvasive positive pressure ventilation (NPPV) can be delivered by using a volume-controlled ventilator, a pressure-controlled ventilator, a bilevel positive airway pressure ventilator, or a continuous positive airway pressure device. During the past decade, there has been a resurgence in the use of noninvasive ventilation, fueled by advances in technology and clinical trials evaluating its use. Several manufacturers produce portable devices that are simple to operate. This review describes the equipment, techniques, and complications associated with NPPV and also the indications for both short-term and long-term applications. NPPV clearly represents an important addition to the techniques available to manage patients with respiratory failure. Future clinical trials evaluating its many clinical applications will help to define populations of patients most apt to benefit from this type of treatment.

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.

Management of severe ischemic cardiomyopathy: left ventricular assist device as destination therapy versus conventional bypass and mitral valve surgery.

PubMed

Maltais, Simon; Tchantchaleishvili, Vahtang; Schaff, Hartzell V; Daly, Richard C; Suri, Rakesh M; Dearani, Joseph A; Topilsky, Yan; Stulak, John M; Joyce, Lyle D; Park, Soon J

2014-04-01

Patients with severe ischemic cardiomyopathy (left ventricular ejection fraction <25%) and severe ischemic mitral regurgitation have a poor survival with medical therapy alone. Left ventricular assist device as destination therapy is reserved for patients who are too high risk for conventional surgery. We evaluated our outcomes with conventional surgery within this population and the comparative effectiveness of these 2 therapies. We identified patients who underwent conventional surgery or left ventricular assist device as destination therapy for severe ischemic cardiomyopathy (left ventricular ejection fraction <25%) and severe mitral regurgitation. The era for conventional surgery spanned from 1993 to 2009 and from 2007 to 2011 for left ventricular assist device as destination therapy. We compared baseline patient characteristics and outcomes in terms of end-organ function and survival. A total of 88 patients were identified; 55 patients underwent conventional surgery (63%), and 33 patients (37%) received a left ventricular assist device as destination therapy. Patients who received left ventricular assist device as destination therapy had the increased prevalence of renal failure, inotrope dependency, and intra-aortic balloon support. Patients undergoing conventional surgery required longer ventilatory support, and patients receiving a left ventricular assist device required more reoperation for bleeding. Mortality rates were similar between the 2 groups at 30 days (7% in the conventional surgery group vs 3% in the left ventricular assist device as destination therapy group, P = .65) and at 1 year (22% in the conventional surgery group vs 15% in the left ventricular assist device as destination therapy group, P = .58). There was a trend toward improved survival in patients receiving a left ventricular assist device compared with the propensity-matched groups at 1 year (94% vs 71%, P = .171). The operative mortality and early survival after conventional surgery seem to be acceptable. For inoperable or prohibitive-risk patients, left ventricular assist device as destination therapy can be offered with similar outcomes. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

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.

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

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

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.

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

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.

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.

Interactive simulation system for artificial ventilation on the internet: virtual ventilator.

PubMed

Takeuchi, Akihiro; Abe, Tadashi; Hirose, Minoru; Kamioka, Koichi; Hamada, Atsushi; Ikeda, Noriaki

2004-12-01

To develop an interactive simulation system "virtual ventilator" that demonstrates the dynamics of pressure and flow in the respiratory system under the combination of spontaneous breathing, ventilation modes, and ventilator options. The simulation system was designed to be used by unexperienced health care professionals as a self-training tool. The system consists of a simulation controller and three modules: respiratory, spontaneous breath, and ventilator. The respiratory module models the respiratory system by three resistances representing the main airway, the right and left lungs, and two compliances also representing the right and left lungs. The spontaneous breath module generates inspiratory negative pressure produced by a patient. The ventilator module generates driving force of pressure or flow according to the combination of the ventilation mode and options. These forces are given to the respiratory module through the simulation controller. The simulation system was developed using HTML, VBScript (3000 lines, 100 kB) and ActiveX control (120 kB), and runs on Internet Explorer (5.5 or higher). The spontaneous breath is defined by a frequency, amplitude and inspiratory patterns in the spontaneous breath module. The user can construct a ventilation mode by setting a control variable, phase variables (trigger, limit, and cycle), and options. Available ventilation modes are: controlled mechanical ventilation (CMV), continuous positive airway pressure, synchronized intermittent mandatory ventilation (SIMV), pressure support ventilation (PSV), SIMV + PSV, pressure-controlled ventilation (PCV), pressure-regulated volume control (PRVC), proportional assisted ventilation, mandatory minute ventilation (MMV), bilevel positive airway pressure (BiPAP). The simulation system demonstrates in a graph and animation the airway pressure, flow, and volume of the respiratory system during mechanical ventilation both with and without spontaneous breathing. We developed a web application that demonstrated the respiratory mechanics and the basic theory of ventilation mode.

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.

Clinical factors associated with success of proportional assist ventilation in the acute phase of critical illness: pilot study.

PubMed

Delgado, M; Zavala, E; Tomás, R; Fernandez, R

2014-03-01

Proportional assist ventilation plus (PAV+) applies pressure depending on the patient's inspiratory effort, automatically adjusting flow and volume assist to changes in respiratory mechanics. We aimed to assess the clinical factors associated with the success of PAV+ as first-line support in the acute phase of critical illness. A prospective cohort study was carried out. Mechanically ventilated patients>24h were switched from assist-control ventilation to PAV+ as soon as they regained spontaneous breathing activity. PAV+ was set to deliver the highest assistance. We compared patients in whom PAV+ succeeded versus those in whom it failed. PAV+ succeeded in 12 (63%) patients, but failed in 7 (37%) due to tachypnea (n=4), hypercapnia (n=2), and metabolic acidosis (n=1), but without statistical significance. Both groups had similar clinical parameters. On the day of inclusion, total work of breathing per breath was lower in the successful PAV+ group (WOBTOT: 0.95 [0.8-1.35] vs. 1.6 [1.4-1.8] J/L; P<.007). The area under the ROC curve was 0.89 ± 0.08 for WOBTOT. The best cut-off for predicting PAV+ success was WOBTOT<1.4 J/L (sensitivity: 1 [0.7-1], specificity: 0.6 [0.4-0.6], PPV: 0.7 [0.5-0.7], and NPV: 1 [0.6-1]). PAV+ proved feasible as first-line ventilatory support in 63% of the patients, mostly in individuals without extreme derangements in WOBTOT. Tachypnea and hypercapnia were the clinical factors associated with failure, though statistical significance was not reached. Copyright © 2013 Elsevier España, S.L. and SEMICYUC. All rights reserved.

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.

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

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.

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

Respiratory drives and exercise in menstrual cycles of athletic and nonathletic women.

PubMed

Schoene, R B; Robertson, H T; Pierson, D J; Peterson, A P

1981-06-01

To investigate the influence of the midluteal and midfollicular phases of the menstrual cycle on exercise performance and ventilatory drives, we studied six outstanding female athletes, six controls with normal menstrual cycles, and six outstanding athletes who were amenorrheic. In all menstruating subjects resting minute ventilation (Ve) and mouth occlusion pressures (P0.1) were higher in the luteal phase (p less than k0.0001 and p less than 0.02, respectively),. Hypoxic (expressed as the hyperbolic shape parameter A) and hypercapnic (expressed as S, deltaVE/delta PAco2) ventilatory responses were increase in the luteal phase (p less than 0.01). The athletes had lower A values during the luteal phase than the nonathletes (p less than 0.001). Maximal exercise response, expressed either as total exercise time or maximum O2 consumption or CO2 production (VO2 max or Vco2 max) was decreased during the luteal phase but was significantly different at a p less than 0.05 level only among the nonathletes. Ventilatory equivalent (VE/VO2) during progressive exercise on a bicycle ergometer was significantly increased during the luteal phase. The amenorrheic athletes showed no changes between the two test periods. The luteal phase of the menstrual cycle induced increases in ventilatory drives and exercise ventilation in both athletes and controls, but the athletes, in contrast to controls, demonstrated no significant decrease in exercise performance in the luteal phase.

Ventilatory thresholds determined from HRV: comparison of 2 methods in obese adolescents.

PubMed

Quinart, S; Mourot, L; Nègre, V; Simon-Rigaud, M-L; Nicolet-Guénat, M; Bertrand, A-M; Meneveau, N; Mougin, F

2014-03-01

The development of personalised training programmes is crucial in the management of obesity. We evaluated the ability of 2 heart rate variability analyses to determine ventilatory thresholds (VT) in obese adolescents. 20 adolescents (mean age 14.3±1.6 years and body mass index z-score 4.2±0.1) performed an incremental test to exhaustion before and after a 9-month multidisciplinary management programme. The first (VT1) and second (VT2) ventilatory thresholds were identified by the reference method (gas exchanges). We recorded RR intervals to estimate VT1 and VT2 from heart rate variability using time-domain analysis and time-varying spectral-domain analysis. The coefficient correlations between thresholds were higher with spectral-domain analysis compared to time-domain analysis: Heart rate at VT1: r=0.91 vs. =0.66 and VT2: r=0.91 vs. =0.66; power at VT1: r=0.91 vs. =0.74 and VT2: r=0.93 vs. =0.78; spectral-domain vs. time-domain analysis respectively). No systematic bias in heart rate at VT1 and VT2 with standard deviations <6 bpm were found, confirming that spectral-domain analysis could replace the reference method for the detection of ventilatory thresholds. Furthermore, this technique is sensitive to rehabilitation and re-training, which underlines its utility in clinical practice. This inexpensive and non-invasive tool is promising for prescribing physical activity programs in obese adolescents. © Georg Thieme Verlag KG Stuttgart · New York.

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

Response of Preterm Infants to 2 Noninvasive Ventilatory Support Systems: Nasal CPAP and Nasal Intermittent Positive-Pressure Ventilation.

PubMed

Silveira, Carmen Salum Thomé; Leonardi, Kamila Maia; Melo, Ana Paula Carvalho Freire; Zaia, José Eduardo; Brunherotti, Marisa Afonso Andrade

2015-12-01

Noninvasive ventilation (NIV) in preterm infants is currently applied using intermittent positive pressure (2 positive-pressure levels) or in a conventional manner (one pressure level). However, there are no studies in the literature comparing the chances of failure of these NIV methods. The aim of this study was to evaluate the occurrence of failure of 2 noninvasive ventilatory support systems in preterm neonates over a period of 48 h. A randomized, prospective, clinical study was conducted on 80 newborns (gestational age < 37 weeks, birthweight < 2,500 g). The infants were randomized into 2 groups: 40 infants were treated with nasal CPAP and 40 infants with nasal intermittent positive-pressure ventilation (NIPPV). The occurrence of apnea, progression of respiratory distress, nose bleeding, and agitation was defined as ventilation failure. The need for intubation and re-intubation after failure was also observed. There were no significant differences in birth characteristics between groups. Ventilatory support failure was observed in 25 (62.5%) newborns treated with nasal CPAP and in 12 (30%) newborns treated with NIPPV, indicating an association between NIV failure and the absence of intermittent positive pressure (odds ratio [OR] 1.22, P < .05). Apnea (32.5%) was the main reason for nasal CPAP failure. After failure, 25% (OR 0.33) of the newborns receiving nasal CPAP and 12.5% (OR 0.14) receiving NIPPV required invasive mechanical ventilation. Ventilatory support failure was significantly more frequent when nasal CPAP was used. Copyright © 2015 by Daedalus Enterprises.

Response characteristics of an aquatic biomonitor used for rapid toxicity detection.

PubMed

van der Schalie, W H; Shedd, T R; Widder, M W; Brennan, L M

2004-01-01

The response characteristics of an aquatic biomonitor that detects toxicity by monitoring changes in bluegill (Lepomis macrochirus Rafinesque) ventilatory and movement patterns were evaluated in single chemical laboratory studies at concentrations near the 96-h LC(50) concentration and at the EILATox-Oregon Workshop in sequential tests of multiple unknown samples. Baseline data collected prior to exposure allows each fish to serve as its own control. When at least 70% of exposed fish exhibit ventilatory or movement parameters significantly different from baseline observations, a group alarm is declared. In the laboratory studies, the aquatic biomonitor responded to the majority of chemicals at the 96-h lc(50) within an hour or less, although substantially higher response times were found for malathion and pentachlorophenol. Workshop tests of single chemical concentrations presented as blind samples were consistent with the laboratory test results. There were no alarms under control conditions in any test. Although data are limited, the aquatic biomonitor appears to respond more rapidly to chemicals causing membrane irritation, narcosis or polar narcosis than to acetylcholinesterase inhibitors or oxidative phosphorylation uncouplers. All four monitored parameters (ventilatory rate, cough rate, ventilatory depth and movement) contributed to identification of first alarms at acutely toxic levels. Understanding these response patterns can be useful in data interpretation for biomonitor applications such as surface water monitoring for watershed protection, wastewater treatment plant effluent monitoring or source water monitoring for drinking water protection. Copyright (c) 2004 John Wiley & Sons, Ltd.

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.

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.

Evolution of the use of noninvasive mechanical ventilation in chronic obstructive pulmonary disease in a Spanish region, 1997-2010.

PubMed

Carpe-Carpe, Bienvenida; Hernando-Arizaleta, Lauro; Ibáñez-Pérez, M Carmen; Palomar-Rodríguez, Joaquín A; Esquinas-Rodríguez, Antonio M

2013-08-01

Noninvasive mechanical ventilation (NIV) appeared in the 1980s as an alternative to invasive mechanical ventilation (IMV) in patients with acute respiratory failure. We evaluated the introduction of NIV and the results in patients with acute exacerbation of chronic obstructive pulmonary disease in the Region of Murcia (Spain). A retrospective observational study based on the minimum basic hospital discharge data of all patients hospitalised for this pathology in all public hospitals in the region between 1997 and 2010. We performed a time trend analysis on hospital attendance, the use of each ventilatory intervention and hospital mortality through joinpoint regression. We identified 30.027 hospital discharges. Joinpoint analysis: downward trend in attendance (annual percentage change [APC]=-3.4, 95% CI: - 4.8; -2.0, P <.05) and in the group without ventilatory intervention (APC=-4.2%, -5.6; -2.8, P <.05); upward trend in the use of NIV (APC=16.4, 12.0; 20. 9, P <.05), and downward trend that was not statistically significant in IMV (APC=-4.5%, -10.3; 1.7). We observed an upward trend without statistical significance in overall mortality (APC=0.5, -1.3; 2.4) and in the group without intervention (APC=0.1, -1.6; 1.9); downward trend with statistical significance in the NIV group (APC=-7.1, -11.7; -2.2, P <.05) and not statistically significant in the IMV group (APC=-0,8, -6, 1; 4.8). The mean stay did not change substantially. The introduction of NIV has reduced the group of patients not receiving assisted ventilation. No improvement in results was found in terms of mortality or length of stay. Copyright © 2012 SEPAR. Published by Elsevier Espana. All rights reserved.

Ventilatory Responses at Peak Exercise in Endurance-Trained Obese Adults

PubMed Central

Lorenzo, Santiago

2013-01-01

Background: 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. Methods: 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. Results: 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 ± 0.76L/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. Conclusion: 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. PMID:23722607

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.

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.

[Guillain-Barré syndrome as differential diagnosis of intervertebral disk-induced nerve root compression].

PubMed

Perlick, L; Möller, G; Wallny, T; Schmitt, O

1999-01-01

Diagnosis of Guillian-Barré Syndrome usually is not difficult, but diagnostic failure occurs for the variable initial presentation. Diagnosis is based on physical examination showing loss of motor strength in more than one limb and loss of deep tendon reflexes. Ventilatory assistance, pharmacologic maintenance of cardiovascular homeostasis, corticosteroids, IgG and plasma exchange are the dominant therapeutic measures. This article reports on a case of a 59-year old surgeon suffering from degenerative disc disease in the lumbar spine. The patient developed a severe course of the Guillian-Barré Syndrome with persisting motor weakness of the legs. If the primary problem at presentation is limb and back pain the pathology appears to be in the musculoskeletal rather than in neurological system. The awareness of this presentation of Guillian-Barré-Syndrome will eliminate delay in diagnosis.

Intra-oral ignition of monopolar diathermy during transnasal humidified rapid-insufflation ventilatory exchange (THRIVE).

PubMed

Onwochei, D; El-Boghdadly, K; Oakley, R; Ahmad, I

2017-06-01

We present the case of unanticipated airway ignition during hard palate biopsy. Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) and monopolar diathermy were utilised for the procedure, during which an arc arose from the diathermy tip to a titanium implant, causing a brief ignition on the monopolar diathermy grip. This case highlights the need for maintained awareness of fire risk when using diathermy in the presence of THRIVE during airway surgery. © 2017 The Association of Anaesthetists of Great Britain and Ireland.

A universal definition of ARDS: the PaO2/FiO2 ratio under a standard ventilatory setting--a prospective, multicenter validation study.

PubMed

Villar, Jesús; Pérez-Méndez, Lina; Blanco, Jesús; Añón, José Manuel; Blanch, Lluís; Belda, Javier; Santos-Bouza, Antonio; Fernández, Rosa Lidia; Kacmarek, Robert M

2013-04-01

The PaO2/FiO2 is an integral part of the assessment of patients with acute respiratory distress syndrome (ARDS). The American-European Consensus Conference definition does not mandate any standardization procedure. We hypothesized that the use of PaO2/FiO2 calculated under a standard ventilatory setting within 24 h of ARDS diagnosis allows a more clinically relevant ARDS classification. We studied 452 ARDS patients enrolled prospectively in two independent, multicenter cohorts treated with protective mechanical ventilation. At the time of ARDS diagnosis, patients had a PaO2/FiO2 ≤ 200. In the derivation cohort (n = 170), we measured PaO2/FiO2 with two levels of positive end-expiratory pressure (PEEP) (≥ 5 and ≥ 10 cmH2O) and two levels of FiO2 (≥ 0.5 and 1.0) at ARDS onset and 24 h later. Dependent upon PaO2 response, patients were reclassified into three groups: mild (PaO2/FiO2 > 200), moderate (PaO2/FiO2 101-200), and severe (PaO2/FiO2 ≤ 100) ARDS. The primary outcome measure was ICU mortality. The standard ventilatory setting that reached the highest significance difference in mortality among these categories was tested in a separate cohort (n = 282). The only standard ventilatory setting that identified the three PaO2/FiO2 risk categories in the derivation cohort was PEEP ≥ 10 cmH2O and FiO2 ≥ 0.5 at 24 h after ARDS onset (p = 0.0001). Using this ventilatory setting, patients in the validation cohort were reclassified as having mild ARDS (n = 47, mortality 17 %), moderate ARDS (n = 149, mortality 40.9 %), and severe ARDS (n = 86, mortality 58.1 %) (p = 0.00001). Our method for assessing PaO2/FiO2 greatly improved risk stratification of ARDS and could be used for enrolling appropriate ARDS patients into therapeutic clinical trials.

Arousal from Sleep Does Not Lead to Reduced Dilator Muscle Activity or Elevated Upper Airway Resistance on Return to Sleep in Healthy Individuals

PubMed Central

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

Study Objectives: 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. Design: Observational study. Setting: Two sleep physiology laboratories. Patients or Participants: 35 men and 25 women with no medical or sleep disorders. Interventions: Auditory tones to induce 3-s to 15-s cortical arousals from sleep. Measurements and Results: 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. Conclusions: 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. Citation: Jordan AS, Cori JM, Dawson A, Nicholas CL, O'Donoghue FJ, Catcheside PG, Eckert DJ, McEvoy RD, Trinder J. Arousal from sleep does not lead to reduced dilator muscle activity or elevated upper airway resistance on return to sleep in healthy individuals. SLEEP 2015;38(1):53–59. PMID:25325511

Ventilatory Cycle Measurements and Loop Gain in Central Apnea in Mining Drivers Exposed to Intermittent Altitude.

PubMed

Rey de Castro, Jorge; Liendo, Alicia; Ortiz, Oswaldo; Rosales-Mayor, Edmundo; Liendo, César

2017-01-15

By measuring the apnea length, ventilatory phase, respiratory cycle length, and loop gain, we can further characterize the central apneas of high altitude (CAHA). 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. 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. 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. © 2017 American Academy of Sleep Medicine

Ventilatory response to the onset of passive and active exercise in human subjects.

PubMed

Miyamura, M; Ishida, K; Yasuda, Y

1992-01-01

Ventilatory responses at the onset of passive and active exercise with different amount of exercising muscle mass were studied in 10 healthy male subjects. Four exercise tests were performed for each subject with appropriate intervals on the same day, i.e., two voluntary exercises of one leg or both legs and two passive exercises of one leg or both legs. Inspiratory minute volume (VI), end-tidal CO2 and O2 partial pressures (PETCO2, PETO2) were measured breath-by-breath using a hot-wire flowmeter, infrared CO2 analyzer, and a rapid O2 analyzer. Average values of VI were obtained from 5 breaths at rest preceding exercise and the first and second breaths after the onset of exercise. The ventilatory response to exercise was calculated as the difference (delta) between the mean of exercise VI and mean of resting VI. In this study, the PETCO2 decreased by about 0.5 Torr in four exercise tests, though the decrement of PETCO2 was not statistically significant. The average values and standard deviation of delta VI were 4.22 +/- 1.63 l/min for the one leg and 6.46 +/- 1.80 l/min for the two legs in the active exercise, and were 2.46 +/- 1.12 l/min for the one leg and 3.44 +/- 1.55 l/min for the two legs in the passive exercise, respectively. These results suggest that in awake conditions, the ventilatory response at the onset of passive or active exercise does not increase additively with the increasing amount of muscle mass being exercised.

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.

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

With age a lower individual breathing reserve is associated with a higher maximal heart rate.

PubMed

Burtscher, Martin; Gatterer, Hannes; Faulhaber, Martin; Burtscher, Johannes

2018-01-01

Maximal heart rate (HRmax) is linearly declining with increasing age. Regular exercise training is supposed to partly prevent this decline, whereas sex and habitual physical activity do not. High exercise capacity is associated with a high cardiac output (HR x stroke volume) and high ventilatory requirements. Due to the close cardiorespiratory coupling, we hypothesized that the individual ventilatory response to maximal exercise might be associated with the age-related HRmax. Retrospective analyses have been conducted on the results of 129 consecutively performed routine cardiopulmonary exercise tests. The study sample comprised healthy subjects of both sexes of a broad range of age (20-86 years). Maximal values of power output, minute ventilation, oxygen uptake and heart rate were assessed by the use of incremental cycle spiroergometry. Linear multivariate regression analysis revealed that in addition to age the individual breathing reserve at maximal exercise was independently predictive for HRmax. A lower breathing reserve due to a high ventilatory demand and/or a low ventilatory capacity, which is more pronounced at a higher age, was associated with higher HRmax. Age explained the observed variance in HRmax by 72% and was improved to 83% when the variable "breathing reserve" was entered. The presented findings indicate an independent association between the breathing reserve at maximal exercise and maximal heart rate, i.e. a low individual breathing reserve is associated with a higher age-related HRmax. A deeper understanding of this association has to be investigated in a more physiological scenario. Copyright © 2017 Elsevier B.V. All rights reserved.

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 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.

Lung function in the absence of respiratory symptoms in overweight children and adolescents*

PubMed Central

de Assunção, Silvana Neves Ferraz; Daltro, Carla Hilário da Cunha; Boa Sorte, Ney Christian; Ribeiro, Hugo da Costa; Bastos, Maria de Lourdes; Queiroz, Cleriston Farias; Lemos, Antônio Carlos Moreira

2014-01-01

OBJECTIVE: To describe lung function findings in overweight children and adolescents without respiratory disease. METHODS: This was a cross-sectional study involving male and female overweight children and adolescents in the 8-18 year age bracket, without respiratory disease. All of the participants underwent anthropometric assessment, chest X-ray, pulse oximetry, spirometry, and lung volume measurements. Individuals with respiratory disease were excluded, as were those who were smokers, those with abnormal chest X-rays, and those with an SpO2 = 92%. Waist circumference was measured in centimeters. The body mass index-for-age Z score for boys and girls was used in order to classify the individuals as overweight, obese, or severely obese. Lung function variables were expressed in percentage of the predicted value and were correlated with the anthropometric indices. RESULTS: We included 59 individuals (30 males and 29 females). The mean age was 11.7 ± 2.7 years. Lung function was normal in 21 individuals (35.6%). Of the 38 remaining individuals, 19 (32.2%), 15 (25.4%), and 4 (6.7%) presented with obstructive, restrictive, and mixed ventilatory disorder, respectively. The bronchodilator response was positive in 15 individuals (25.4%), and TLC measurements revealed that all of the individuals with reduced VC had restrictive ventilatory disorder. There were significant negative correlations between the anthropometric indices and the Tiffeneau index in the individuals with mixed ventilatory disorder. CONCLUSIONS: Lung function was abnormal in approximately 65% of the individuals evaluated here, all of whom were overweight. Obstructive ventilatory disorder and positive bronchodilator response predominated. PMID:24831397

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

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

Pulmonary outcome of esophageal atresia patients and its potential causes in early childhood.

PubMed

Dittrich, René; Stock, Philippe; Rothe, Karin; Degenhardt, Petra

2017-08-01

The aim of this study was to illustrate the pulmonary long term outcome of patients with repaired esophageal atresia and to further examine causes and correlations that might have led to this outcome. Twenty-seven of 62 possible patients (43%) aged 5-20years, with repaired esophageal atresia were recruited. Body plethysmography and spirometry were performed to evaluate lung function, and the Bruce protocol treadmill exercise test to assess physical fitness. Results were correlated to conditions such as interpouch distance, gastroesophageal reflux or duration of post-operative mechanical ventilation. Seventeen participants (63%) showed abnormal lung function at rest or after exercise. Restrictive ventilatory defects (solely restrictive or combined) were found in 11 participants (41%), and obstructive ventilatory defects (solely obstructive or combined) in 13 subjects (48%). Twenty-two participants (81%) performed the Bruce protocol treadmill exercise test to standard. The treadmill exercise results were expressed in z-score and revealed to be significantly below the standard population mean (z-score=-1.40). Moreover, significant correlations between restrictive ventilatory defects and the interpouch distance; duration of post-operative ventilation; gastroesophageal reflux disease; plus recurrent aspiration pneumonia during infancy; were described. It was shown that esophageal atresia and associated early complications have significant impact on pulmonary long term outcomes such as abnormal lung function and, in particular restrictive ventilatory defects. Long-running and regular follow-ups of patients with congenital esophageal atresia are necessary in order to detect and react to the development and progression of associated complications such as ventilation disorders or gastroesophageal reflux disease. Prognosis study, Level II. Copyright © 2016 Elsevier Inc. All rights reserved.

Factors affecting the response to exercise in patients with severe pulmonary arterial hypertension.

PubMed

Flox-Camacho, Angela; Escribano-Subías, Pilar; Jiménez-López Guarch, Carmen; Fernández-Vaquero, Almudena; Martín-Ríos, Dolores; de la Calzada-Campo, Carlos Sáenz

2011-01-01

Ergospirometry objectively quantifies exercise capacity. Up until now, the response to exercise evaluated by ergospirometry in patients with pulmonary arterial hypertension has only been described in recently diagnosed.patients. Our aim is to describe the response to exercise in patients with severe pulmonary arterial hypertension under specific treatment and define which parameters determine their exercise capacity. A cross-sectional study was performed on 80 patients, 57 women, aged 45 (14), with severe pulmonary arterial hypertension (48 idiopathic, 14 related to toxic rapeseed oil, 13 to connective tissue disease, 5 to human immunodeficiency virus), mean pulmonary pressure at diagnosis 61(15)mmHg and after 49(33) months under treatment since diagnosis. Biomarkers were measured and echocardiography and ergospirometry were performed the same day. Our patients, under specific treatment, showed the typical behaviour of patients with pulmonary arterial hypertension with less limitation of both aerobic capacity and ventilatory efficiency. Being male (p=0.004), high ventilatory equivalent for carbon dioxide at anaerobic threshold (p<0.001) or biomarkers (p=0.006) were the strongest predictors of impaired peak oxygen uptake in multivariate analysis, whereas for an impaired percentage achieved of predicted value were right ventricle diastolic diameter (p<0.001), months of treatment (p=0.01) and high ventilatory equivalent for CO(2) (p<0.001). In pulmonary arterial hypertension, right ventricle dysfunction (expressed by its dilation or high NTproBNP) and impaired ventilatory inefficiency as well as being male or a short time under treatment can be considered as determining factors of impaired exercise capacity. Copyright © 2010 SEPAR. Published by Elsevier Espana. All rights reserved.

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.

[Cheyne-Stokes respiration and cardiovascular risk].

PubMed

Duchna, H-W; Schultze-Werninghaus, G

2009-07-01

Due to its high prevalence in patients with heart failure and its negative predictive value concerning morbidity and mortality, Cheyne-Stokes respiration (CSR) is a sleep disorders of major interest. CSR correlates with the degree of heart failure and is characterised by a typical crescendo/decrescendo breathing pattern combined with phases of central sleep apnoea, caused by pulmonary oedema and oscillation of ventilatory control. Thus, CSR is a marker of the severity of heart failure. Treatment of CSR first involves optimisation of heart failure therapy by cardiologists and then application of non-invasive means of ventilatory support. Treatment of patients with severe heart failure with non-invasive positive pressure ventilatory support leads to a significant reduction of CSR, sympathetic activity, and daytime sleepiness and improves cardiac output and 6-minute walking distance. At present, a prospective randomised, controlled intervention-study (Serve-HF study) is being conducted in order to show if therapy of CSR can improve patient survival. This review describes the pathophysiology, epidemiology, and therapeutic options of CSR with a special focus on the elevated cardiovascular risk of patients with CSR.

Reduced suppression of CO2-induced ventilatory stimulation by endomorphins relative to morphine.

PubMed

Czapla, Marc A; Zadina, James E

2005-10-19

Opioids are among the most effective analgesics, but a major limitation for their therapeutic usefulness is their induction of respiratory depression. Endomorphin-1 (EM1), in contrast to several other mu opioids, exhibits a threshold for respiratory depression that is well above its threshold for analgesia. Its effect on sensitivity to CO(2), however, remains unknown. Minute ventilation (V(E)) in 2, 4, and 6% CO(2) was measured before and after systemic administration of EM1, endomorphin-2 (EM2), DAMGO, and morphine in the conscious rat. EM1 and EM2 attenuated the hypercapnic ventilatory response (HCVR) only in high doses, while DAMGO and morphine diminished the HCVR in much lower doses. The ventilatory effects of high doses of all 4 agonists were blocked by the mu-opioid antagonist naloxone (0.4 mg/kg i.v.), but not by the peripherally restricted mu-opioid antagonist, methyl-naloxone (0.4 mg/kg i.v.). It was concluded that the endomorphins attenuated the HCVR only in large doses, well beyond the analgesic threshold, and did so through a centrally mediated mu-opioid mechanism.

Comparative study of lung functions in women working in different fibre industries.

PubMed

Khanam, F; Islam, N; Hai, M A

2008-07-01

A cross sectional work has been done on Bangladeshi females, working in different fibre industries, to study the effect of exposure to fibre dust on pulmonary functions. The ventilatory capacities were measured by VMI ventilometer in 653 apparently healthy women (160, 162 and 167 were jute, textile and garment industry workers, respectively). For the controls 164 females were recruited who never worked in any fibre industry. The observed FVC, FEV1 and PEFR were lower in all groups of fibre industry workers than those of the control. Among the industry workers, the jute mill workers had the lowest ventilatory capacities and garment industry workers had the highest values. The jute and textile mill workers had also significantly lower FEV1 and PEFR than those of garment industry workers. The FEV1 and PEFR were significantly lower in jute mill workers than those of textile ill workers. The low ventilatory capacities were almost proportionate with the length of service of the workers. Thus, the present study indicates that the fibre dust, on regular exposure for longer duration, may limit the lung functions.

HIF-1 and ventilatory acclimatization to chronic hypoxia

PubMed Central

Powell, Frank L.; Fu, Zhenxing

2008-01-01

Ventilatory acclimatization to hypoxia (VAH) is a time-dependent increase in ventilation and ventilatory O2-sensitivity that involves plasticity in carotid body chemoreceptors and CNS respiratory centers. Hypoxia inducible factor-1α (HIF-1α) controls the expression of several genes that increase physiological O2 supply. Studies using transgenic mice show HIF-1α expression in the carotid bodies and CNS with chronic sustained and intermittent hypoxia is important for VAH. Other O2-sensitive transcription factors such as HIF-2α may be important for VAH by reducing metabolic O2 demands also. Specific gene targets of HIF-1α shown to be involved in VAH include erythropoietin, endothelin-1, neuronal nitric oxide synthase and tyrosine hydroxylase. Other HIF-1α targets that may be involved in VAH include vascular endothelial growth factor, heme oxygenase 1 and cytoglobin. Interactions between these multiple pathways and feedback control of HIF-1α expression from some of the targets support a complex and powerful role for HIF-1α in neural plasticity of physiological control circuits with chronic hypoxia. PMID:18708172

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.

The role of spinal cord transmission in the ventilatory response to electrically induced exercise in the anaesthetized dog

PubMed Central

Cross, Brenda A.; Davey, A.; Guz, A.; Katona, P. G.; Maclean, M.; Murphy, K.; Semple, S. J. G.; Stidwill, R.

1982-01-01

1. The ventilatory response to electrically induced `exercise' was studied in six chloralose-anaesthetized dogs. The on-transient and steady-state responses to `exercise' were compared in the same dogs before and after spinal cord transection at T8/9 (dermatome level T6/7) on fifteen occasions. 2. Phasic hind limb `exercise' was induced for periods of 4 min by passing current (2 Hz modulated 50 Hz sine wave) between two needles inserted through the hamstring muscles. The maximum current used was 30 mA. This was below the level previously found to produce an artifactual stimulation of breathing with the cord intact. 3. Cord transection produced no significant change in either the resting values of ventilation (˙VI) and CO2 production (˙VCO2) or the ventilatory equivalent for CO2 during `exercise' (△ ˙VI/ △ ˙VCO2). 4. During the steady state of exercise Pa, CO2 was on average significantly lower than at rest with the cord intact (mean △Pa, CO2, - 2·1 mmHg; range - 5·7 to + 1), and higher, though not significantly, with the cord cut (mean Pa, CO2, + 1·2 mmHg; range - 1·5 to + 4·3). However, even in the absence of spinal cord transmission, the ventilatory response to exercise could not be accounted for on the basis of CO2 sensitivity; the △ ˙VI/ △Pa,CO2 obtained with exercise (apparent sensitivity) was significantly greater than that obtained with CO2 inhalation (true sensitivity) both before and after cord section. 5. ˙VI and ˙VCO2 increased more slowly with the cord cut than with the cord intact. This was thought to be due to a slower increase in venous return in the absence of sympathetic innervation of the lower half of the body following cord transection. 6. Similar experiments were performed during muscle paralysis (following gallamine triethiodide). Ventilation was maintained with a respirator controlled by phrenic nerve activity. These experiments showed an increase in ventilation, independent of muscle contraction, which was only present when the cord was intact and which was confined to the on-transient. Only in the absence of spinal cord transmission could there be certainty that the dynamics of the ventilatory response to electrically induced `exercise' was free of artifact. 7. It was concluded that spinal cord transmission is not necessary for the steady-state ventilatory response to electrically induced exercise of the hind limbs. 8. The dog with spinal cord transection provides a suitable model for the study of the chemical control of breathing during electrically induced exercise. PMID:6292406

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

The comfort of breathing: a study with volunteers assessing the influence of various modes of assisted ventilation.

PubMed

Russell, W C; Greer, J R

2000-11-01

To assess the subjective feeling of comfort of healthy volunteers breathing on various modes of ventilation used in intensive care. A randomized, prospective, double-blinded, crossover trial using volunteers. An intensive care unit (ICU) in a teaching hospital. We compared, by using healthy volunteers, the subjective feeling of comfort of three modes of ventilation used during the weaning phase of critical illness. We used healthy volunteers to avoid other distracting influences of intensive care that may confound the primary feeling of comfort. The modes we compared were synchronized intermittent mandatory ventilation, assisted spontaneous breathing, and biphasic positive airway pressure. The imposed ventilation was comparable with 50% of the volunteers' normal respiratory effort. The volunteers breathed via a mouthpiece through a ventilator circuit, and the modes of ventilation were introduced in a randomized manner. We measured visual analog scores for comfort for the three modes of ventilation and collected a ranking order and open-ended comments. We demonstrated that at the level of support we imposed, assisted spontaneous breathing was the most comfortable mode of ventilation and that synchronized intermittent mandatory ventilation was the most uncomfortable. These results were strongly supported by both the ranking scale and comments of the volunteers. Assisted spontaneous breathing was the most comfortable mode of ventilation because the pattern was primarily determined by the volunteer. Synchronized intermittent mandatory ventilation was the most uncomfortable because the ventilatory pattern was imposed on the volunteers, leading to ventilator-volunteer dyssynchrony. We also conclude there is wide individual variation in the subjective feeling of comfort. Whereas the mode of ventilation in ICUs is based primarily on the physiologic needs of the patient, the feeling of comfort may be considered when choosing an appropriate mode of ventilation during the weaning phase of critical illness.

A taxonomy for mechanical ventilation: 10 fundamental maxims.

PubMed

Chatburn, Robert L; El-Khatib, Mohamad; Mireles-Cabodevila, Eduardo

2014-11-01

The American Association for Respiratory Care has declared a benchmark for competency in mechanical ventilation that includes the ability to "apply to practice all ventilation modes currently available on all invasive and noninvasive mechanical ventilators." This level of competency presupposes the ability to identify, classify, compare, and contrast all modes of ventilation. Unfortunately, current educational paradigms do not supply the tools to achieve such goals. To fill this gap, we expand and refine a previously described taxonomy for classifying modes of ventilation and explain how it can be understood in terms of 10 fundamental constructs of ventilator technology: (1) defining a breath, (2) defining an assisted breath, (3) specifying the means of assisting breaths based on control variables specified by the equation of motion, (4) classifying breaths in terms of how inspiration is started and stopped, (5) identifying ventilator-initiated versus patient-initiated start and stop events, (6) defining spontaneous and mandatory breaths, (7) defining breath sequences (8), combining control variables and breath sequences into ventilatory patterns, (9) describing targeting schemes, and (10) constructing a formal taxonomy for modes of ventilation composed of control variable, breath sequence, and targeting schemes. Having established the theoretical basis of the taxonomy, we demonstrate a step-by-step procedure to classify any mode on any mechanical ventilator. Copyright © 2014 by Daedalus Enterprises.

Tolerance of Volume Control Noninvasive Ventilation in Subjects With Amyotrophic Lateral Sclerosis.

PubMed

Martínez, Daniel; Sancho, Jesús; Servera, Emilio; Marín, Julio

2015-12-01

Noninvasive ventilation (NIV) tolerance has been identified as an independent predictor of survival in amyotrophic lateral sclerosis (ALS). Volume control continuous mandatory ventilation (VC-CMV) NIV has been associated with poor tolerance. The aim of this study was to determine the tolerance of subjects with ALS to VC-CMV NIV. This was a prospective study involving subjects with ALS who were treated with VC-CMV NIV. Respiratory and functional parameters were recorded when the subjects began ventilatory support. NIV tolerance was evaluated after 3 months. Eighty-seven subjects with ALS were included. After 3 months, 80 subjects (92%) remained tolerant of NIV. Tolerant subjects presented greater survival (median 22.0 months, 95% CI 14.78-29.21) than intolerant subjects (median 6.0 months, 95% CI 0.86-11.13) (P = .03). The variables that best predicted NIV tolerance were mechanically assisted cough peak flow (P = .01) and percentage of time spent with SpO2 < 90% at night while on NIV (P = .03) CONCLUSIONS: VC-CMV NIV provides high rates of NIV tolerance in subjects with ALS. Mechanically assisted cough peak flow and percentage of time spent with SpO2 < 90% at night while using NIV are the 2 factors associated with tolerance of VC-CMV NIV in subjects with ALS. Copyright © 2015 by Daedalus Enterprises.

High Mid-Flow to Vital Capacity Ratio and the Response to Exercise in Children With Congenital Heart Disease.

PubMed

Vilozni, Daphna; Alcaneses-Ofek, Maria Rosario; Reuveny, Ronen; Rosenblum, Omer; Inbar, Omri; Katz, Uriel; Ziv-Baran, Tomer; Dubnov-Raz, Gal

2016-12-01

Pulmonary mechanics may play a role in exercise intolerance in patients with congenital heart disease (CHD). A reduced FVC volume could increase the ratio between mid-flow (FEF 25-75% ) and FVC, which is termed high dysanapsis. The relationship between high dysanapsis and the response to maximum-intensity exercise in children with CHD had not yet been studied. The aim of this work was to examine whether high dysanapsis is related to the cardiopulmonary response to maximum-intensity exercise in pediatric subjects with CHD. We retrospectively collected data from 42 children and adolescents with CHD who had either high dysanapsis (ratio >1.2; n = 21) or normal dysanapsis (control) (n = 21) as measured by spirometry. Data extracted from cardiopulmonary exercise test reports included peak values of heart rate, work load, V̇ O 2 , V̇ CO 2 , and ventilation parameters and submaximum values, including ventilatory threshold and ventilatory equivalents. There were no significant differences in demographic and clinical parameters between the groups. Participants with high dysanapsis differed from controls in lower median peak oxygen consumption (65.8% vs 83.0% of predicted, P = .02), peak oxygen pulse (78.6% vs 87.8% of predicted, P = .02), ventilatory threshold (73.8% vs 85.3% of predicted, P = .03), and maximum breathing frequency (106% vs 121% of predicted, P = .035). In the high dysanapsis group only, median peak ventilation and tidal volume were significantly lower than 80% of predicted values. In children and adolescents with corrected CHD, high dysanapsis was associated with a lower ventilatory capacity and reduced aerobic fitness, which may indicate respiratory muscle impairments. Copyright © 2016 by Daedalus Enterprises.

Effects of exercise position on the ventilatory responses to exercise in chronic heart failure.

PubMed

Armour, W; Clark, A L; McCann, G P; Hillis, W S

1998-09-01

Patients with heart failure frequently complain of orthopnoea. The objective was to assess the ventilatory response of patients with chronic heart failure during erect and supine exercise. Maximal incremental exercise testing with metabolic gas exchange measurements in erect and supine positions conducted in random order. Tertiary referral centre for cardiology. Nine patients with heart failure (aged 61.9+/-6.1 years) and 10 age matched controls (63.8+/-4.6). Metabolic gas exchange measurements. The slope of the relation between ventilation and carbon dioxide production. Ratings of perceived breathlessness during exercise. Oxygen consumption (VO2) and ventilation were higher during erect exercise at each stage in each group. Peak VO2 was [mean (SD)] 17.12 ml/kg/min (4.07) erect vs 12.92 (3.61) supine in the patients (P<0.01) and 22.62 (5.03) erect-supine vs 19.16 (3.78) erect (P<0.01) in the controls. Ratings of perceived exertion were higher in the patients at each stage, but unaffected by posture. There was no difference in the slope of the relation between ventilation and carbon dioxide production between erect and supine exercise 36.39 (6.12) erect vs 38.42 (8.89) supine for patients; 30.05 (4.52) vs 28.80 (3.96) for controls. In this group of patients during exercise, there was no change in the perception of breathlessness, nor the ventilatory response to carbon dioxide production with change in posture, although peak ventilation was greater in the erect position. The sensation of breathlessness may be related to the appropriateness of the ventilatory response to exertion rather than to the absolute ventilation.

The effect of music therapy on physiological signs of anxiety in patients receiving mechanical ventilatory support.

PubMed

Korhan, Esra Akin; Khorshid, Leyla; Uyar, Mehmet

2011-04-01

The aim of this study was to investigate if relaxing music is an effective method of reducing the physiological signs of anxiety in patients receiving mechanical ventilatory support. Few studies have focused on the effect of music on physiological signs of anxiety in patients receiving mechanical ventilatory support. A study-case-control, experimental repeated measures design was used. Sixty patients aged 18-70 years, receiving mechanical ventilatory support and hospitalised in the intensive care unit, were taken as a convenience sample. Participants were randomised to a control group or intervention group, who received 60 minutes of music therapy. Classical music was played to patients using media player (MP3) and headphones. Subjects had physiological signs taken immediately before the intervention and at the 30th, 60th and 90th minutes of the intervention. Physiological signs of anxiety assessed in this study were mean systolic and diastolic blood pressure, pulse rate, respiratory rate and oxygen saturation in blood measured by pulse oxymetry. Data were collected over eight months in 2006-2007. The music group had significantly lower respiratory rates, and systolic and diastolic blood pressure, than the control group. This decrease improved progressively in the 30th, 60th and 90th minutes of the intervention, indicating a cumulative dose effect. Music can provide an effective method of reducing potentially harmful physiological responses arising from anxiety. As indicated by the results of this study, music therapy can be supplied to allay anxiety in patients receiving mechanical ventilation. Nurses may include music therapy in the routine care of patients receiving mechanical ventilation. © 2011 Blackwell Publishing Ltd.

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

Anaerobic threshold assessment through the ventilatory method during roller-ski skating testing: right or wrong?

PubMed

Fabre, Nicolas; Bortolan, Lorenzo; Pellegrini, Barbara; Zerbini, Livio; Mourot, Laurent; Schena, Federico

2012-02-01

This study aimed at questioning the validity of the ventilatory method to determine the anaerobic threshold (respiratory compensation point [RCP]) during an incremental roller-ski skating test to exhaustion. Nine elite crosscountry skiers were evaluated. The skiers carried out an incremental roller-ski test on a treadmill with the V2 skating technique. Ventilatory parameters were continuously collected breath by breath, thanks to a portable gas exchange measurement system. Poling signal was obtained using instrumented ski poles. For each stage, ventilatory and poling signals were synchronized and averaged. The poor coefficient of interobserver reliability for the time at RCP confirmed the great difficulty felt by the 3 blinded reviewers for the RCP determination. Moreover, the reviewer agreed with the impossibility of determining RCP in 4 of the 9 skiers. There was no significant difference between breathing frequency (Bf) and poling frequency (Pf) during the last 8 stages. However, it seems that the differences observed during the first stages arose from the use of either a strictly 1:1 or a 1:2 Bf to Pf ratio when the exercise intensity was still moderate. So, even if there were significant differences between the frequencies, the Bf was strictly subordinate to the Pf during the entire test. In the same way, the normalized tidal volume and peak poling forces curves were superposable. These findings showed that when the upper body is mainly involved in the propulsion, the determinants of the ventilation are strictly dependent on the poling pattern during an incremental test to exhaustion. Thus, during roller-ski skating, the determination of RCP must be used cautiously because too much depending on mechanical factors.

Respiratory constraints during activities in daily life and the impact on health status in patients with early-stage COPD: a cross-sectional study.

PubMed

van Helvoort, Hanneke Ac; Willems, Laura M; Dekhuijzen, Pn Richard; van Hees, Hieronymus Wh; Heijdra, Yvonne F

2016-10-13

In patients with chronic obstructive pulmonary disease (COPD), exercise capacity is reduced, resulting over time in physical inactivity and worsened health status. It is unknown whether ventilatory constraints occur during activities of daily life (ADL) in early stages of COPD. The aim of this study was to assess respiratory mechanics during ADL and to study its consequences on dyspnoea, physical activity and health status in early-stage COPD compared with healthy controls. In this cross-sectional study, 39 early-stage COPD patients (mean FEV 1 88±s.d. 12% predicted) and 20 controls performed 3 ADL: climbing stairs, vacuum cleaning and displacing groceries in a cupboard. Respiratory mechanics were measured during ADL. Physical activity was measured with accelerometry. Health status was assessed by the Nijmegen Clinical Screening Instrument. Compared with controls, COPD patients had greater ventilatory inefficiency and higher ventilatory requirements during ADL (P<0.05). Dyspnoea scores were increased in COPD compared with controls (P<0.001). During ADL, >50% of the patients developed dynamic hyperinflation in contrast to 10-35% of the controls. Higher dyspnoea was scored by patients with dynamic hyperinflation. Physical activity was low but comparable between both groups. From the patients, 55-84% experienced mild-to-severe problems in health status compared with 5-25% of the controls. Significant ventilatory constraints already occur in early-stage COPD patients during common ADL and result in increased dyspnoea. Physical activity level is not yet reduced, but many patients already experience limitations in health status. These findings reinforce the importance of early diagnosis of COPD and assessment of more than just spirometry.

Antenatal smoking and substance-misuse, infant and newborn response to hypoxia.

PubMed

Ali, Kamal; Rosser, Thomas; Bhat, Ravindra; Wolff, Kim; Hannam, Simon; Rafferty, Gerrard F; Greenough, Anne

2017-05-01

To determine at the peak age for sudden infant death syndrome (SIDS) the ventilatory response to hypoxia of infants whose mothers substance misused in pregnancy (SM infants), or smoked during pregnancy (S mothers) and controls whose mothers neither substance misused or smoked. In addition, we compared the ventilatory response to hypoxia during the neonatal period and peak age of SIDS. Infants of S or SM mothers compared to control infants would have a poorer ventilatory response to hypoxia at the peak age of SIDS. Prospective, observational study. Twelve S; 12 SM and 11 control infants were assessed at 6-12 weeks of age and in the neonatal period. Changes in minute volume, oxygen saturation, heart rate, and end tidal carbon dioxide levels on switching from breathing room air to 15% oxygen were assessed. Maternal and infant urine samples were tested for cotinine, cannabinoids, opiates, amphetamines, methadone, cocaine, and benzodiazepines. The S and SM infants had a greater decline in minute volume (P = 0.037, P = 0.016, respectively) and oxygen saturation (P = 0.031) compared to controls. In all groups, the magnitude of decline in minute volume in response to hypoxia was higher in the neonatal period compared to at 6-12 weeks (P < 0.001). Both maternal substance misuse and smoking were associated with an impaired response to a hypoxic challenge at the peak age for SIDS. The hypoxic ventilatory decline was more marked in the neonatal period compared to the peak age for SIDS indicating a maturational effect. Pediatr Pulmonol. 2017;52:650-655. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

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

Respiratory Mechanical and Cardiorespiratory Consequences of Cycling with Aerobars.

PubMed

Charlton, Jesse M; Ramsook, Andrew H; Mitchell, Reid A; Hunt, Michael A; Puyat, Joseph H; Guenette, Jordan A

2017-12-01

Aerobars place a cyclist in a position where the trunk is flexed forward and the elbows are close to the midline of the body. This position is known to improve cycling aerodynamics and time trial race performance compared with upright cycling positions. However, the aggressive nature of this position may have important cardiorespiratory and metabolic consequences. The purpose of this investigation was to examine the respiratory mechanical, ventilatory, metabolic, and sensory consequences of cycling while using aerobars during laboratory-based cycling. Eleven endurance-trained male cyclists (age, 26 ± 9 yr; V˙O2peak, 55 ± 5 mL·kg·min) were recruited. Visit 1 consisted of an incremental cycling test to determine peak power output. Visit 2 consisted of 6-min bouts of constant load cycling at 70% of peak incremental power output in the aerobar position, drop position, and upright position while grasping the brake hoods. Metabolic and ventilatory responses were measured using a commercially available metabolic cart, and respiratory pressures were measured using an esophageal catheter. Cycling in the aerobar position significantly increased the work of breathing (Wb), power of breathing (Pb), minute ventilation, ventilatory equivalent for oxygen and carbon dioxide, and transdiaphragmatic pressure compared with the upright position. Increases in the Wb and Pb in the aerobars relative to the upright position were strongly correlated with the degree of thoracic restriction, measured as the shoulder-to-aerobar width ratio (Wb: r = 0.80, P = 0.01; Pb: r = 0.69, P = 0.04). Aerobars significantly increase the mechanical cost of breathing and leads to greater ventilatory inefficiency compared with upright cycling. Future work is needed to optimize aerobar width to minimize the respiratory mechanical consequences while optimizing aerodynamics.

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.

[A case of emergency surgery in a patient with bronchial asthma under continuous spinal anesthesia].

PubMed

Noda, Keiichi; Ryo, Kenshu; Nakamoto, Ai

2003-10-01

A 78-year-old male, observed for bronchial asthma, underwent two emergency operations within eight days. The first operation was performed under general anesthesia with tracheal intubation. Anesthesia was maintained by sevoflurane-oxygen and continuous infusion of propofol in combination with epidural injection of lidocaine. During the operation, respiratory sound was almost clear. But wheezing occurred as he awoke after discontinuation of the anesthetics. He needed ventilatory support for three days for status asthmatics. The second operation was performed under continuous spinal anesthesia using hypobaric tetracaine and hyperbaric bupivacaine. No ventilatory support was necessary after the operation and he was discharged uneventfully.

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.

Ventilatory support in critically ill hematology patients with respiratory failure

PubMed Central

2012-01-01

Introduction Hematology patients admitted to the ICU frequently experience respiratory failure and require mechanical ventilation. Noninvasive mechanical ventilation (NIMV) may decrease the risk of intubation, but NIMV failure poses its own risks. Methods To establish the impact of ventilatory management and NIMV failure on outcome, data from a prospective, multicenter, observational study were analyzed. All hematology patients admitted to one of the 34 participating ICUs in a 17-month period were followed up. Data on demographics, diagnosis, severity, organ failure, and supportive therapies were recorded. A logistic regression analysis was done to evaluate the risk factors associated with death and NIVM failure. Results Of 450 patients, 300 required ventilatory support. A diagnosis of congestive heart failure and the initial use of NIMV significantly improved survival, whereas APACHE II score, allogeneic transplantation, and NIMV failure increased the risk of death. The risk factors associated with NIMV success were age, congestive heart failure, and bacteremia. Patients with NIMV failure experienced a more severe respiratory impairment than did those electively intubated. Conclusions NIMV improves the outcome of hematology patients with respiratory insufficiency, but NIMV failure may have the opposite effect. A careful selection of patients with rapidly reversible causes of respiratory failure may increase NIMV success. PMID:22827955

Role of central and peripheral opiate receptors in the effects of fentanyl on analgesia, ventilation and arterial blood-gas chemistry in conscious rats

PubMed Central

Henderson, Fraser; May, Walter J.; Gruber, Ryan B.; Discala, Joseph F.; Puscovic, Veljko; Young, Alex P.; Baby, Santhosh M.; Lewis, Stephen J.

2015-01-01

This study determined the effects of the peripherally restricted µ-opiate receptor (µ-OR) antagonist, naloxone methiodide (NLXmi) on fentanyl (25 µg/kg, i.v.)-induced changes in (1) analgesia, (2) arterial blood gas chemistry (ABG) and alveolar-arterial gradient (A-a gradient), and (3) ventilatory parameters, in conscious rats. The fentanyl-induced increase in analgesia was minimally affected by a 1.5 mg/kg of NLXmi but was attenuated by a 5.0 mg/kg dose. Fentanyl decreased arterial blood pH, pO2 and sO2 and increased pCO2 and A-a gradient. These responses were markedly diminished in NLXmi (1.5 mg/kg)-pretreated rats. Fentanyl caused ventilatory depression (e.g., decreases in tidal volume and peak inspiratory flow). Pretreatment with NLXmi (1.5 mg/kg, i.v.) antagonized the fentanyl decrease in tidal volume but minimally affected the other responses. These findings suggest that (1) the analgesia and ventilatory depression caused by fentanyl involve peripheral µ-ORs and (2) NLXmi prevents the fentanyl effects on ABG by blocking the negative actions of the opioid on tidal volume and A-a gradient. PMID:24284037

T3 supplementation affects ventilatory timing & glucose levels in type 2 diabetes mellitus model.

PubMed

Bollinger, Stephen S; Weltman, Nathen Y; Gerdes, A Martin; Schlenker, Evelyn H

2015-01-01

Type II diabetes mellitus (T2DM) can affect ventilation, metabolism, and fasting blood glucose levels. Hypothyroidism may be a comorbidity of T2DM. In this study T2DM was induced in 20 female Sprague Dawley rats using Streptozotocin (STZ) and Nicotinamide (N). One of experimental STZ/N groups (N=10 per group) was treated with a low dose of triiodothyronine (T3). Blood glucose levels, metabolism and ventilation (in air and in response to hypoxia) were measured in the 3 groups. STZ/N-treated rats increased fasting blood glucose compared to control rats eight days and 2 months post-STZ/N injections indicating stable induction of T2DM state. Treatments had no effects on ventilation, metabolism or body weight. After one month of T3 supplementation, there were no physiological indications of hyperthyroidism, but T3 supplementation altered ventilatory timing and decreased blood glucose levels compared to STZ/N rats. These results suggest that low levels of T3 supplementation could offer modest effects on blood glucose and ventilatory timing in this T2M model. Copyright © 2014 Elsevier B.V. All rights reserved.

Ventilatory Patterning in a Mouse Model of Stroke

PubMed Central

Koo, Brian B; Strohl, Kingman P; Gillombardo, Carl B; Jacono, Frank J

2010-01-01

Cheyne-Stokes respiration (CSR) is a breathing pattern characterized by waxing and waning of breath volume and frequency, and is often recognized following stroke, when causal pathways are often obscure. We used an animal model to address the hypothesis that cerebral infarction is a mechanism for producing breathing instability. Fourteen male A/J mice underwent either stroke (n=7) or sham (n=7) procedure. Ventilation was measured using whole body plethysmography. Respiratory rate (RR), tidal volume (VT) and minute ventilation (Ve) mean values and coefficient of variation were computed for ventilation and oscillatory behavior. In addition, the ventilatory data were computationally fit to models to quantify autocorrelation, mutual information, sample entropy and a nonlinear complexity index. At the same time post procedure, stroke when compared to sham animal breathing consisted of a lower RR and autocorrelation, higher coefficient of variation for VT and higher coefficient of variation for Ve. Mutual information and the nonlinear complexity index were higher in breathing following stroke which also demonstrated a waxing/waning pattern. The absence of stroke in the sham animals was verified anatomically. We conclude that ventilatory pattern following cerebral infarction demonstrated increased variability with increased nonlinear patterning and a waxing/waning pattern, consistent with CSR. PMID:20472101

Recent advances on the functional and evolutionary morphology of the amniote respiratory apparatus.

PubMed

Lambertz, Markus

2016-02-01

Increased organismic complexity in metazoans was achieved via the specialization of certain parts of the body involved in different faculties (structure-function complexes). One of the most basic metabolic demands of animals in general is a sufficient supply of all tissues with oxygen. Specialized structures for gas exchange (and transport) consequently evolved many times and in great variety among bilaterians. This review focuses on some of the latest advancements that morphological research has added to our understanding of how the respiratory apparatus of the primarily terrestrial vertebrates (amniotes) works and how it evolved. Two main components of the respiratory apparatus, the lungs as the "exchanger" and the ventilatory apparatus as the "active pump," are the focus of this paper. Specific questions related to the exchanger concern the structure of the lungs of the first amniotes and the efficiency of structurally simple snake lungs in health and disease, as well as secondary functions of the lungs in heat exchange during the evolution of sauropod dinosaurs. With regard to the active pump, I discuss how the unique ventilatory mechanism of turtles evolved and how understanding the avian ventilatory strategy affects animal welfare issues in the poultry industry. © 2016 New York Academy of Sciences.

Periodic breathing and oxygen supplementation in Chilean miners at high altitude (4200m).

PubMed

Moraga, Fernando A; Jiménez, Daniel; Richalet, Jean Paul; Vargas, Manuel; Osorio, Jorge

2014-11-01

Our objective was to determine the nocturnal ventilatory pattern and characterize the effect of oxygen enrichment on nocturnal ventilatory pattern and sleep quality in miners exposed to intermittent hypobaric hypoxia at 4200m. A total of 16 acclimatized miners were studied. Nocturnal ventilatory pattern (plethysmographic inductance), arterial oxygen saturation and heart rate (pulse oximetry) were performed in 9/16 subjects. Sleep quality at high altitude was assessed by self-questionnaires in 16/16 subjects. All measurements were performed during at least 7h of sleep. Subjects were studied while sleeping at high altitude without (control, C) and with oxygen supplementation (FiO2=0.25, treated, T). Periodic breathing (%) C: 25±18 vs T: 6.6±5.6 (p<0.05), apneas index (no./h) C: 34.9±24.1 vs T: 8.5±6.8 (p<0.05); and sleep quality C: 17.8±3.4 vs T: 12.1±2.2 (p<0.0001) were evaluated. In conclusion, periodic breathing with apneas was present in miners exposed to high altitude for 1 to 4 years and was reduced by treatment with supplementary oxygen. Copyright © 2014 Elsevier B.V. All rights reserved.

Bronchitis in men employed in the coke industry

PubMed Central

Walker, D. D.; Archibald, R. M.; Attfield, M. D.

1971-01-01

Walker, D. D., Archibald, R. M., and Attfield, M. D. (1971).Brit. J. industr. Med.,28, 358-363. Bronchitis in men employed in the coke industry. An epidemiological survey to determine the prevalence of bronchitis in men employed at two of the National Coal Board's coking plants is described. Eight hundred and eighty-one men (91%) of the total working population were examined. A strong association was found between bronchitis prevalence and cigarette smoking (P < 0·001). In addition, men who smoked and who were exposed to high temperatures, dust, and fumes in the environment of the coke-ovens had more bronchitis than men who worked elsewhere in the cokeworks (P < 0·02). Both the presence of bronchitis and employment in the environment of the coke-ovens had significant and independent effects on ventilatory capacity. The combination of cigarette smoking and previous employment in a dusty industry also had a significant effect on ventilatory capacity. The investigation suggests that cigarette smoking, and the combination of smoking and pollution from the coke-ovens and previous occupation, appear to be important factors in the aetiology of bronchitis and reduced ventilatory capacity in men employed in the coke manufacturing industry. PMID:5124835

The effect of metabolic alkalosis on the ventilatory response in healthy subjects.

PubMed

Oppersma, E; Doorduin, J; van der Hoeven, J G; Veltink, P H; van Hees, H W H; Heunks, L M A

2018-02-01

Patients with acute respiratory failure may develop respiratory acidosis. Metabolic compensation by bicarbonate production or retention results in posthypercapnic alkalosis with an increased arterial bicarbonate concentration. The hypothesis of this study was that elevated plasma bicarbonate levels decrease respiratory drive and minute ventilation. In an intervention study in 10 healthy subjects the ventilatory response using a hypercapnic ventilatory response (HCVR) test was assessed, before and after administration of high dose sodium bicarbonate. Total dose of sodiumbicarbonate was 1000 ml 8.4% in 3 days. Plasma bicarbonate increased from 25.2 ± 2.2 to 29.2 ± 1.9 mmol/L. With increasing inspiratory CO 2 pressure during the HCVR test, RR, V t , Pdi, EAdi and V E increased. The clinical ratio ΔV E /ΔP et CO 2 remained unchanged, but Pdi, EAdi and V E were significantly lower after bicarbonate administration for similar levels of inspired CO 2 . This study demonstrates that in healthy subjects metabolic alkalosis decreases the neural respiratory drive and minute ventilation, as a response to inspiratory CO 2 . Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Stress-induced thermotolerance of ventilatory motor pattern generation in the locust, Locusta migratoria.

PubMed

Newman, Amy E M; Foerster, Melody; Shoemaker, Kelly L; Robertson, R Meldrum

2003-11-01

Ventilation is a crucial motor activity that provides organisms with an adequate circulation of respiratory gases. For animals that exist in harsh environments, an important goal is to protect ventilation under extreme conditions. Heat shock, anoxia, and cold shock are environmental stresses that have previously been shown to trigger protective responses. We used the locust to examine stress-induced thermotolerance by monitoring the ability of the central nervous system to generate ventilatory motor patterns during a subsequent heat exposure. Preparations from pre-stressed animals had an increased incidence of motor pattern recovery following heat-induced failure, however, prior stress did not alter the characteristics of the ventilatory motor pattern. During constant heat exposure at sub-lethal temperatures, we observed a protective effect of heat shock pre-treatment. Serotonin application had similar effects on motor patterns when compared to prior heat shock. These studies are consistent with previous studies that indicate prior exposure to extreme temperatures and hypoxia can protect neural operation against high temperature stress. They further suggest that the protective mechanism is a time-dependent process best revealed during prolonged exposure to extreme temperatures and is mediated by a neuromodulator such as serotonin.

Reducing the Indication for Ventilatory Support in the Severely Burned Patient: Results of a New Protocol Approach at a Regional Burn Center.

PubMed

Gille, Jochen; Bauer, Nicole; Malcharek, Michael J; Dragu, Adrian; Sablotzki, Armin; Taha, Hischam; Czeslick, Elke

2016-01-01

Initial management of the severely injured routinely includes sedation and mechanical ventilatory support. However, nonjudiciously applied mechanical ventilatory support can itself lead to poorer patient outcomes. In an attempt to reduce this iatrogenic risk, a standardized, in-house, five-point protocol providing clinical guidance on the use and duration of ventilation was introduced and analyzed, and the impact on patient outcomes was assessed. In 2007, a protocol for early spontaneous breathing was introduced and established in clinical practice. This protocol included: 1) early extubation (≤6 hours after admission) in the absence of absolute ventilatory indication; 2) avoidance of "routine intubation" in spontaneously breathing patients; 3) early postoperative extubation, including patients requiring multiple surgical interventions; 4) intensive chest and respiratory physiotherapy with routine application of expectorants; and 5) early active mobilization. A retrospective clinical study compared patients (group A) over a 2-year period admitted under the new protocol with a historical patient group (group B). Patients in group A (n = 38) had fewer ventilator days over the time-course of treatment (3 [1; 5.8] vs 18.5 days [0.5; 20.5]; P = .0001) with a lower rate of tracheostomies (15.8 vs 54%; P = .0003). Patients on ventilation at admission in group A had shorter ventilation periods after admission (4.75 [4; 22.25] vs 378 hours [8.5; 681.5]; P = .0003), and 66.7% of these patients were extubated within 6 hours of admission (vs 9.1% in group B). No patients fulfilling the inclusion criteria required re- or emergency intubation. In the first 5 days of treatment, significantly lower Sequential Organ Failure Assessment scores were recorded in group A. There was also a trend for lower mortality rates (0 [0%] vs 6 [14%]), sepsis rates (24 [63.2%] vs 37 [88.1%]), and cumulative fluid balance on days 3 and 7 in group A. In contrast, group A demonstrated an elevated rate of pneumonia (15 [39.5%] vs 8 [19%]). These trends, however, lacked statistical significance. Our five-point protocol was safe and easily translated into clinical practice. In the authors experience, this protocol significantly reduced the ventilatory period in severely injured. Furthermore, this study suggests that many injured may be over-treated with routine ventilation, which carries accompanying risks.

Effects of patient-directed music intervention on anxiety and sedative exposure in critically ill patients receiving mechanical ventilatory support: a randomized clinical trial.

PubMed

Chlan, Linda L; Weinert, Craig R; Heiderscheit, Annie; Tracy, Mary Fran; Skaar, Debra J; Guttormson, Jill L; Savik, Kay

2013-06-12

Alternatives to sedative medications, such as music, may alleviate the anxiety associated with ventilatory support. To test whether listening to self-initiated patient-directed music (PDM) can reduce anxiety and sedative exposure during ventilatory support in critically ill patients. Randomized clinical trial that enrolled 373 patients from 12 intensive care units (ICUs) at 5 hospitals in the Minneapolis-St Paul, Minnesota, area receiving acute mechanical ventilatory support for respiratory failure between September 2006 and March 2011. Of the patients included in the study, 86% were white, 52% were female, and the mean (SD) age was 59 (14) years. The patients had a mean (SD) Acute Physiology, Age and Chronic Health Evaluation III score of 63 (21.6) and a mean (SD) of 5.7 (6.4) study days. Self-initiated PDM (n = 126) with preferred selections tailored by a music therapist whenever desired while receiving ventilatory support, self-initiated use of noise-canceling headphones (NCH; n = 122), or usual care (n = 125). Daily assessments of anxiety (on 100-mm visual analog scale) and 2 aggregate measures of sedative exposure (intensity and frequency). Patients in the PDM group listened to music for a mean (SD) of 79.8 (126) (median [range], 12 [0-796]) minutes/day. Patients in the NCH group wore the noise-abating headphones for a mean (SD) of 34.0 (89.6) (median [range], 0 [0-916]) minutes/day. The mixed-models analysis showed that at any time point, patients in the PDM group had an anxiety score that was 19.5 points lower (95% CI, -32.2 to -6.8) than patients in the usual care group (P = .003). By the fifth study day, anxiety was reduced by 36.5% in PDM patients. The treatment × time interaction showed that PDM significantly reduced both measures of sedative exposure. Compared with usual care, the PDM group had reduced sedation intensity by -0.18 (95% CI, -0.36 to -0.004) points/day (P = .05) and had reduced frequency by -0.21 (95% CI, -0.37 to -0.05) points/day (P = .01). The PDM group had reduced sedation frequency by -0.18 (95% CI, -0.36 to -0.004) points/day vs the NCH group (P = .04). By the fifth study day, the PDM patients received 2 fewer sedative doses (reduction of 38%) and had a reduction of 36% in sedation intensity. Among ICU patients receiving acute ventilatory support for respiratory failure, PDM resulted in greater reduction in anxiety compared with usual care, but not compared with NCH. Concurrently, PDM resulted in greater reduction in sedation frequency compared with usual care or NCH, and greater reduction in sedation intensity compared with usual care, but not compared with NCH. clinicaltrials.gov Identifier: NCT00440700.

Amyotrophic lateral sclerosis: A 40-year personal perspective.

PubMed

Eisen, Andrew

2009-04-01

Amyotrophic lateral sclerosis (ALS) or motor neuron disease (MND) shares with other neurodegenetrative disorders of the aging nervous system a polygenic, multifactorial aetiology. Less than 10% are familial and these too probably are associated with several interactive genes. The onset of ALS predates development of clinical symptoms by an unknown interval which may extend several years. The cause of neurodegeneration remains unknown but a common end-point is protein misfolding which in turn causes cell function failure. The complex nature of ALS has hindered therapeutic advances. In recent years longer survival is attributable largely to institution of non-invasive ventilation with BiPAP and timely implementation of percutaneous endoscopic gastrostomy (PEG) feeding. Symptomatic treatment has advanced improving quality of life. Several encouraging avenues of therapy for ALS are beginning to be emerge raising hope for real benefit. They include protective autoimmunity, vaccines against misfolded protein epitopes and other deleterious species, new drug delivery systems employing nanotechnology and the potential of stem cell therapy.

The influence of music during mechanical ventilation and weaning from mechanical ventilation: A review

PubMed Central

Hetland, Breanna; Lindquist, Ruth; Chlan, Linda L.

2015-01-01

Background Mechanical ventilation (MV) causes many distressing symptoms. Weaning, the gradual decrease in ventilator assistance leading to termination of MV, increases respiratory effort, which may exacerbate symptoms and prolong MV. Music, a non-pharmacological intervention without side effects may benefit patients during weaning from mechanical ventilatory support. Methods A narrative review of OVID Medline, PsychINFO, and CINAHL databases was conducted to examine the evidence for the use of music intervention in MV and MV weaning. Results Music intervention had a positive impact on ventilated patients; 16 quantitative and 2 qualitative studies were identified. Quantitative studies included randomized clinical trials (10), case controls (3), pilot studies (2) and a feasibility study. Conclusions Evidence supports music as an effective intervention that can lesson symptoms related to MV and promote effective weaning. It has potential to reduce costs and increase patient satisfaction. However, more studies are needed to establish its use during MV weaning. PMID:26227333

Hereditary myopathies with early respiratory insufficiency in adults.

PubMed

Naddaf, Elie; Milone, Margherita

2017-11-01

Hereditary myopathies with early respiratory insufficiency as a predominant feature of the clinical phenotype are uncommon and underestimated in adults. We reviewed the clinical and laboratory data of patients with hereditary myopathies who demonstrated early respiratory insufficiency before the need for ambulatory assistance. Only patients with disease-causing mutations or a specific histopathological diagnosis were included. Patients with cardiomyopathy were excluded. We identified 22 patients; half had isolated respiratory symptoms at onset. The diagnosis of the myopathy was often delayed, resulting in delayed ventilatory support. The most common myopathies were adult-onset Pompe disease, myofibrillar myopathy, multi-minicore disease, and myotonic dystrophy type 1. Single cases of laminopathy, MELAS (mitochondrial encephalomyopathy with lactic acidosis and strokelike events), centronuclear myopathy, and cytoplasmic body myopathy were identified. We highlighted the most common hereditary myopathies associated with early respiratory insufficiency as the predominant clinical feature, and underscored the importance of a timely diagnosis for patient care. Muscle Nerve 56: 881-886, 2017. © 2017 Wiley Periodicals, Inc.

Peak oxygen uptake, ventilatory efficiency and QRS-duration predict event free survival in patients late after surgical repair of tetralogy of Fallot.

PubMed

Müller, Jan; Hager, Alfred; Diller, Gerhard-Paul; Derrick, Graham; Buys, Roselien; Dubowy, Karl-Otto; Takken, Tim; Orwat, Stefan; Inuzuka, Ryo; Vanhees, Luc; Gatzoulis, Michael; Giardini, Alessandro

2015-10-01

Patients with repaired tetralogy of Fallot (ToF) have an increased long-term risk of cardiovascular morbidity and mortality. Risk stratification in this population is difficult. Initial evidence suggests that cardiopulmonary exercise testing (CPET) may be helpful to risk-stratify patients with repaired ToF. We studied 875 patients after surgical repair for ToF (358 females, age 25.5 ± 11.7 year, range 7-75 years) who underwent CPET between 1999 and 2009. During a mean follow-up of 4.1 ± 2.6 years after CPET, 30 patients (3.4%) died or had sustained ventricular tachycardia (VT). 225 patients (25.7%) had other cardiac related events (emergency admission, surgery, or catheter interventions). On multivariable Cox regression-analysis, %predicted peak oxygen uptake (V˙O2 %) (p=0.001), resting QRS duration (p=0.030) and age (p<0.001) emerged as independent predictors of mortality or sustained VT. Patients with a peak V˙O2 ≤ 65% of predicted and a resting QRS duration ≥ 170 ms had a 11.4-fold risk of death or sustained VT. Ventilatory efficiency expressed as V˙E/V˙CO2 slope (p<0.001), peak V˙O2 % (p=.001), QRS duration (p=.001) and age (p=0.046) independently predicted event free survival. V˙E/V˙CO2 slope ≥ 31.0, peak V˙O2 % ≤ 65% and QRS duration ≥ 170 ms were the cut-off points with best sensitivity and specificity to detect an unfavorable outcome. CPET is an important predictive tool that may assist in the risk stratification of patients with ToF. Subjects with a poor exercise capacity in addition to a prolonged QRS duration have a substantially increased risk for death or sustained ventricular tachycardia, as well as for cardiac-related hospitalizations. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

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 ...

Role of central and peripheral opiate receptors in the effects of fentanyl on analgesia, ventilation and arterial blood-gas chemistry in conscious rats.

PubMed

Henderson, Fraser; May, Walter J; Gruber, Ryan B; Discala, Joseph F; Puskovic, Veljko; Young, Alex P; Baby, Santhosh M; Lewis, Stephen J

2014-01-15

This study determined the effects of the peripherally restricted μ-opiate receptor (μ-OR) antagonist, naloxone methiodide (NLXmi) on fentanyl (25μg/kg, i.v.)-induced changes in (1) analgesia, (2) arterial blood gas chemistry (ABG) and alveolar-arterial gradient (A-a gradient), and (3) ventilatory parameters, in conscious rats. The fentanyl-induced increase in analgesia was minimally affected by a 1.5mg/kg of NLXmi but was attenuated by a 5.0mg/kg dose. Fentanyl decreased arterial blood pH, pO2 and sO2 and increased pCO2 and A-a gradient. These responses were markedly diminished in NLXmi (1.5mg/kg)-pretreated rats. Fentanyl caused ventilatory depression (e.g., decreases in tidal volume and peak inspiratory flow). Pretreatment with NLXmi (1.5mg/kg, i.v.) antagonized the fentanyl decrease in tidal volume but minimally affected the other responses. These findings suggest that (1) the analgesia and ventilatory depression caused by fentanyl involve peripheral μ-ORs and (2) NLXmi prevents the fentanyl effects on ABG by blocking the negative actions of the opioid on tidal volume and A-a gradient. Copyright © 2013 Elsevier B.V. All rights reserved.

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.

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.

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.

[Mechanical ventilation in acute asthma crisis].

PubMed

Barbas, Carmen Sílvia Valente; Pinheiro, Bruno do Valle; Vianna, Arthur; Magaldi, Ricardo; Casati, Ana; José, Anderson; Okamoto, Valdelis Novis

2007-06-01

The II Brazilian Consensus Conference on Mechanical Ventilation was published in 2000. Knowledge on the field of mechanical ventilation evolved rapidly since then, with the publication of numerous clinical studies with potential impact on the ventilatory management of critically ill patients. Moreover, the evolving concept of evidence - based medicine determined the grading of clinical recommendations according to the methodological value of the studies on which they are based. This explicit approach has broadened the understanding and adoption of clinical recommendations. For these reasons, AMIB - Associação de Medicina Intensiva Brasileira and SBPT - Sociedade Brasileira de Pneumologia e Tisiologia - decided to update the recommendations of the II Brazilian Consensus. Mechanical ventilation in the asthma attack has been one of the updated topics. Describe the most important topics on the mechanical ventilation during the asthma attack and suggest the main therapeutic approaches. Systematic review of the published literature and gradation of the studies in levels of evidence, using the key words "mechanical ventilation" and "asthma". We present recommendations on the ventilatory modes and settings to be adopted when ventilating a patient during an asthma attack, as well as the recommended monitoring. Alternative ventilation techniques are also presented. Protective ventilatory strategies are recommended when ventilating a patient during a severe asthma attack.

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.

New approaches in the rehabilitation of the traumatic high level quadriplegic.

PubMed

Bach, J R

1991-02-01

The use of noninvasive alternatives to tracheostomy for ventilatory support have been described in the patient management of various neuromuscular disorders. The use of these techniques for patients with traumatic high level quadriplegia, however, is hampered by the resort to tracheostomy in the acute hospital setting. Twenty traumatic high level quadriplegic patients on intermittent positive pressure ventilation (IPPV) via tracheostomy with little or no ability for unassisted breathing were converted to noninvasive ventilatory support methods and had their tracheostomy sites closed. Four additional patients were ventilated by noninvasive methods without tracheostomy. These methods included the use of body ventilators and the noninvasive intermittent positive airway pressure alternatives of IPPV via the mouth, nose, or custom acrylic strapless oral-nasal interface (SONI). Overnight end-tidal pCO2 studies and monitoring of oxyhemoglobin saturation (SaO2) were used to adjust ventilator volumes and to document effective ventilation during sleep. No significant complications have resulted from the use of these methods over a period of 45 patient-years. Elimination of the tracheostomy permitted significant free time by glossopharyngeal breathing for four patients, two of whom had no measurable vital capacity. We conclude that noninvasive ventilatory support alternatives can be effective and deserve further study in this patient population.

REAL-TIME MONITORING FOR TOXICITY CAUSED BY ...

EPA Pesticide Factsheets

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) to detect developing toxic conditions in water.In laboratory tests, acutely toxic levels of both brevetoxin (PbTx-2) and toxic Pfiesteria piscicida cultures caused fish responses primarily through large increases in cough rate. In the field, the automated biomonitoring system operated continuously for 3 months on the Chicamacomico River, a tributary to the Chesapeake Bay that has had a history of intermittent toxic algal blooms. Data gathered through this effort complemented chemical monitoring data collected by the Maryland Department of Natural Resources (DNR) as part of their Pfiesteria monitoring program. After evaluation by DNR personnel, the public could access the data on the DNR Internet web site at www.dnr.state.md.us/bay/pfiesteria/00results.html or receive more detailed information at www.aquaticpath.umd.edu/empact.. The field biomonitor identified five fish response events. Increased conductivity combined with a substantial decrease in water temperature was the likely cause of one event, while contaminants (probably surfactants) released from inadequately rinsed particle filters produced another response. The other three events, characterized by greatly increased cough ra

Disorders of Sleep and Ventilatory Control in Prader-Willi Syndrome

PubMed Central

Gillett, Emily S.; Perez, Iris A.

2016-01-01

Prader-Willi syndrome (PWS) is an imprinted genetic disorder conferred by loss of paternal gene expression from chromosome 15q11.2-q13. Individuals with PWS have impairments in ventilatory control and are predisposed toward sleep disordered breathing due to a combination of characteristic craniofacial features, obesity, hypotonia, and hypothalamic dysfunction. Children with PWS progress from failure to thrive during infancy to hyperphagia and morbid obesity during later childhood and onward. Similarly, the phenotype of sleep disordered breathing in PWS patients also evolves over time from predominantly central sleep apnea in infants to obstructive sleep apnea (OSA) in older children. Behavioral difficulties are common and may make establishing effective therapy with continuous positive airway pressure (CPAP) more challenging when OSA persists after adenotonsillectomy. Excessive daytime sleepiness (EDS) is also common in patients with PWS and may continue after OSA is effectively treated. We describe here the characteristic ventilatory control deficits, sleep disordered breathing, and excessive daytime sleepiness seen in individuals with PWS. We review respiratory issues that may contribute to sudden death events in PWS patients during sleep and wakefulness. We also discuss therapeutic options for treating sleep disordered breathing including adenotonsillectomy, weight loss, and CPAP. Lastly, we discuss the benefits and safety considerations related to growth hormone therapy. PMID:28933403

Disorders of Sleep and Ventilatory Control in Prader-Willi Syndrome.

PubMed

Gillett, Emily S; Perez, Iris A

2016-07-08

Prader-Willi syndrome (PWS) is an imprinted genetic disorder conferred by loss of paternal gene expression from chromosome 15q11.2-q13. Individuals with PWS have impairments in ventilatory control and are predisposed toward sleep disordered breathing due to a combination of characteristic craniofacial features, obesity, hypotonia, and hypothalamic dysfunction. Children with PWS progress from failure to thrive during infancy to hyperphagia and morbid obesity during later childhood and onward. Similarly, the phenotype of sleep disordered breathing in PWS patients also evolves over time from predominantly central sleep apnea in infants to obstructive sleep apnea (OSA) in older children. Behavioral difficulties are common and may make establishing effective therapy with continuous positive airway pressure (CPAP) more challenging when OSA persists after adenotonsillectomy. Excessive daytime sleepiness (EDS) is also common in patients with PWS and may continue after OSA is effectively treated. We describe here the characteristic ventilatory control deficits, sleep disordered breathing, and excessive daytime sleepiness seen in individuals with PWS. We review respiratory issues that may contribute to sudden death events in PWS patients during sleep and wakefulness. We also discuss therapeutic options for treating sleep disordered breathing including adenotonsillectomy, weight loss, and CPAP. Lastly, we discuss the benefits and safety considerations related to growth hormone therapy.

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 influence of sprint interval training on body composition, physical and metabolic fitness in adolescents and young adults with intellectual disability: a randomized controlled trial.

PubMed

Boer, Pieter-Henk; Meeus, Mira; Terblanche, Elmarie; Rombaut, Lies; Wandele, Inge De; Hermans, Linda; Gysel, Tineke; Ruige, Johannes; Calders, Patrick

2014-03-01

In this study we evaluated the effect of sprint interval training on metabolic and physical fitness in adolescents and young adults with intellectual disabilities when compared with continuous aerobic training and no training (control). Fifty-four persons with intellectual disabilities (age: 17 (3.0), body mass index: 27.7 (3.7), intelligence quotient: 59 (8.6)) were matched based on age, gender and intelligence quotient between sprint interval training (n = 17), continuous aerobic training (n = 15) and control (n = 14). Sprint interval training was composed of three blocks of 10 minutes at ventilatory threshold (blocks 1 and 3: 10 sprint bouts of 15 seconds, followed by 45 seconds relative rest; block 2: continuous training) twice a week for 15 weeks. Continuous aerobic training was composed of three blocks of 10 minutes continuous training. After eight weeks, intensity was increased to 110% of ventilatory threshold. The control group did not participate in supervised exercise training. Before and after the training period, body composition, physical and metabolic fitness were evaluated. Sprint interval training showed a significant positive evolution for waist circumference, fat%, systolic blood pressure, lipid profile, fasting insulin, homeostasis model assessment of insulin resistance, peak VO2, peak Watt, ventilatory threshold, 6-minute walk distance and muscle fatigue resistance when compared with no training (P < 0.01). The sprint interval training group demonstrated significant improvements for fat%, systolic blood pressure, low-density lipoprotein, fasting insulin, peak VO2 and peak power and ventilatory threshold (P < 0.01) when compared with continuous aerobic training. In this study we could observe that sprint interval training has stronger beneficial effects on body composition, physical fitness and metabolic fitness compared with control. Compared with continuous aerobic training, sprint interval training seems to result in better outcome.

Understanding nurses' decision-making when managing weaning from mechanical ventilation: a study of novice and experienced critical care nurses in Scotland and Greece.

PubMed

Kydonaki, Kalliopi; Huby, Guro; Tocher, Jennifer; Aitken, Leanne M

2016-02-01

To examine how nurses collect and use cues from respiratory assessment to inform their decisions as they wean patients from ventilatory support. Prompt and accurate identification of the patient's ability to sustain reduction of ventilatory support has the potential to increase the likelihood of successful weaning. Nurses' information processing during the weaning from mechanical ventilation has not been well-described. A descriptive ethnographic study exploring critical care nurses' decision-making processes when weaning mechanically ventilated patients from ventilatory support in the real setting. Novice and expert Scottish and Greek nurses from two tertiary intensive care units were observed in real practice of weaning mechanical ventilation and were invited to participate in reflective interviews near the end of their shift. Data were analysed thematically using concept maps based on information processing theory. Ethics approval and informed consent were obtained. Scottish and Greek critical care nurses acquired patient-centred objective physiological and subjective information from respiratory assessment and previous knowledge of the patient, which they clustered around seven concepts descriptive of the patient's ability to wean. Less experienced nurses required more encounters of cues to attain the concepts with certainty. Subjective criteria were intuitively derived from previous knowledge of patients' responses to changes of ventilatory support. All nurses used focusing decision-making strategies to select and group cues in order to categorise information with certainty and reduce the mental strain of the decision task. Nurses used patient-centred information to make a judgment about the patients' ability to wean. Decision-making strategies that involve categorisation of patient-centred information can be taught in bespoke educational programmes for mechanical ventilation and weaning. Advanced clinical reasoning skills and accurate detection of cues in respiratory assessment by critical care nurses will ensure optimum patient management in weaning mechanical ventilation. © 2016 John Wiley & Sons Ltd.

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.

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).

Occurrence of respiratory symptoms in persons with restrictive ventilatory impairment compared with persons with chronic obstructive pulmonary disease: The PLATINO study.

PubMed

Nonato, Nívia L; Nascimento, Oliver A; Padilla, Rogelio P; de Oca, Maria M; Tálamo, Carlos; Valdivia, Gonzalo; Lisboa, Carmen; López, Maria V; Celli, Bartolomé; Menezes, Ana Maria B; Jardim, José R

2015-08-01

Patients with chronic obstructive pulmonary disease (COPD) usually complain of symptoms such as cough, sputum, wheezing, and dyspnea. Little is known about clinical symptoms in individuals with restrictive ventilatory impairment. The aim of this study was to compare the prevalence and type of respiratory symptoms in patients with COPD to those reported by individuals with restrictive ventilatory impairment in the Proyecto Latinoamericano de Investigacion en Obstruccion Pulmonar study. Between 2002 and 2004, individuals ≥40 years of age from five cities in Latin America performed pre and post-bronchodilator spirometry and had their respiratory symptoms recorded in a standardized questionnaire. Among the 5315 individuals evaluated, 260 (5.1%) had a restrictive spirometric diagnosis (forced vital capacity (FVC) < lower limit of normal (LLN) with forced expiratory volume in the first second to forced vital capacity ratio (FEV1/FVC) ≥ LLN; American Thoracic Society (ATS)/European Respiratory Society (ERS) 2005) and 610 (11.9%) were diagnosed with an obstructive pattern (FEV1/FVC < LLN; ATS/ERS 2005). Patients with mild restriction wheezed more ((30.8%) vs. (17.8%); p < 0.028). No difference was seen in dyspnea, cough, and sputum between the two groups after adjusting for severity stage. The health status scores for the short form 12 questionnaire were similar in restricted and obstructed patients for both physical (48.4 ± 9.4 vs. 48.3 ± 9.8) and mental (50.8 ± 10.6 vs. 50.0 ± 11.5) domains. Overall, respiratory symptoms are not frequently reported by patients with restricted and obstructed patterns as defined by spirometry. Wheezing was more frequent in patients with restricted pattern compared with those with obstructive ventilatory defect. However, the prevalence of cough, sputum production, and dyspnea are not different between the two groups when adjusted by the same severity stage. © The Author(s) 2015.

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

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.

Acute Toxicity, Respiratory Reaction, and Sensitivity of Three Cyprinid Fish Species Caused by Exposure to Four Heavy Metals

PubMed Central

Wang, Hongjun; Liang, Youguang; Li, Sixin; Chang, Jianbo

2013-01-01

Using 3 cyprinid fish species zebra fish, rare minnow, and juvenile grass carp, we conducted assays of lethal reaction and ventilatory response to analyze sensitivity of the fish to 4 heavy metals. Our results showed that the 96 h LC50 of Hg2+ to zebra fish, juvenile grass carp, and rare minnow were 0.14 mg L−1, 0.23 mg L−1, and 0.10 mg L−1, respectively; of Cu2+0.17 mg L−1, 0.09 mg L−1, and 0.12 mg L−1 respectively; of Cd2+6.5 mg L−1, 18.47 mg L−1, 5.36 mg L−1, respectively; and of Zn2+44.48 mg L−1, 31.37 mg L−1, and 12.74 mg L−1, respectively. Under a 1-h exposure, the ventilatory response to the different heavy metals varied. Ventilatory frequency (Vf) and amplitude (Va) increased in zebra fish, juvenile grass carp, and rare minnows exposed to Hg2+ and Cu2+ (P<0.05), and the Vf and Va of the 3 species rose initially and then declined when exposed to Cd2+. Zn2+ had markedly different toxic effects than the other heavy metals, whose Vf and Va gradually decreased with increasing exposure concentration (P<0.05). The rare minnow was the most highly susceptible of the 3 fish species to the heavy metals, with threshold effect concentrations (TEC) of 0.019 mg L−1, 0.046 mg L−1, 2.142 mg L−1, and 0.633 mg L−1 for Hg2+, Cu2+, Cd2+, and Zn2+, respectively. Therefore, it is feasible to use ventilatory parameters as a biomarker for evaluating the pollution toxicity of metals and to recognize early warning signs by using rare minnows as a sensor. PMID:23755209

Changes in ventilatory threshold with exercise training in a sedentary population: the HERITAGE Family Study.

PubMed

Gaskill, S E; Walker, A J; Serfass, R A; Bouchard, C; Gagnon, J; Rao, D C; Skinner, J S; Wilmore, J H; Leon, A S

2001-11-01

The purpose of this study was to evaluate the effect of exercise training intensity relative to the ventilatory threshold (VT) on changes in work (watts) and VO2 at the ventilatory threshold and at maximal exercise in previously sedentary participants in the HERITAGE Family Study. We hypothesized that those who exercised below their VT would improve less in VO2 at the ventilatory threshold (VO2vt) and VO2max than those who trained at an intensity greater than their VT. Supervised cycle ergometer training was performed at the 4 participating clinical centers, 3 times a week for 20 weeks. Exercise training progressed from the HR corresponding to 55% VO2max for 30 minutes to the HR associated with 75% VO2max for 50 minutes for the final 6 weeks. VT was determined at baseline and after exercise training using standardized methods. 432 sedentary white and black men (n = 224) and women (n = 208), aged 17 to 65 years, were retrospectively divided into groups based on whether exercise training was initiated below, at, or above VT. 1) Training intensity (relative to VT) accounting for about 26% of the improvement in VO2vt (R2 = 0.26, p < 0.0001). 2) The absolute intensity of training in watts (W) accounted for approximately 56% of the training effect at VT (R2 = 0.56, p < 0.0001) with post-training watts at VT (VT(watts)) being not significantly different than W during training (p > 0.70). 3) Training intensity (relative to VT) had no effect on DeltaVO2max. These data clearly show that as a result of aerobic training both the VO2 and W associated with VT respond and become similar to the absolute intensity of sustained (3 x /week for 50 min) aerobic exercise training. Higher intensities of exercise, relative to VT, result in larger gains in VO2vt but not in VO2max.

Relationship between motor corticospinal excitability and ventilatory response during intense exercise.

PubMed

Yunoki, Takahiro; Matsuura, Ryouta; Yamanaka, Ryo; Afroundeh, Roghayyeh; Lian, Chang-Shun; Shirakawa, Kazuki; Ohtsuka, Yoshinori; Yano, Tokuo

2016-06-01

Effort sense has been suggested to be involved in the hyperventilatory response during intense exercise (IE). However, the mechanism by which effort sense induces an increase in ventilation during IE has not been fully elucidated. The aim of this study was to determine the relationship between effort-mediated ventilatory response and corticospinal excitability of lower limb muscle during IE. Eight subjects performed 3 min of cycling exercise at 75-85 % of maximum workload twice (IE1st and IE2nd). IE2nd was performed after 60 min of resting recovery following 45 min of submaximal cycling exercise at the workload corresponding to ventilatory threshold. Vastus lateralis muscle response to transcranial magnetic stimulation of the motor cortex (motor evoked potentials, MEPs), effort sense of legs (ESL, Borg 0-10 scale), and ventilatory response were measured during the two IEs. The slope of ventilation (l/min) against CO2 output (l/min) during IE2nd (28.0 ± 5.6) was significantly greater than that (25.1 ± 5.5) during IE1st. Mean ESL during IE was significantly higher in IE2nd (5.25 ± 0.89) than in IE1st (4.67 ± 0.62). Mean MEP (normalized to maximal M-wave) during IE was significantly lower in IE2nd (66 ± 22 %) than in IE1st (77 ± 24 %). The difference in mean ESL between the two IEs was significantly (p < 0.05, r = -0.82) correlated with the difference in mean MEP between the two IEs. The findings suggest that effort-mediated hyperventilatory response to IE may be associated with a decrease in corticospinal excitability of exercising muscle.

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

Ventilatory oscillations at exercise: effects of hyperoxia, hypercapnia, and acetazolamide.

PubMed

Hermand, Eric; Lhuissier, François J; Larribaut, Julie; Pichon, Aurélien; Richalet, Jean-Paul

2015-06-01

Periodic breathing has been found in patients with heart failure and sleep apneas, and in healthy subjects in hypoxia, during sleep and wakefulness, at rest and, recently, at exercise. To unravel the cardiorespiratory parameters liable to modulate the amplitude and period of ventilatory oscillations, 26 healthy subjects were tested under physiological (exercise) and environmental (hypoxia, hyperoxia, hyperoxic hypercapnia) stresses, and under acetazolamide (ACZ) treatment. A fast Fourier transform spectral analysis of breath-by-breath ventilation (V˙E) evidenced an increase in V˙E peak power under hypercapnia (vs. normoxia and hyperoxia, P < 0.001) and a decrease under ACZ (vs. placebo, P < 0.001), whereas it was not modified in hyperoxia. V˙E period was shortened by exercise in all conditions (vs. rest, P < 0.01) and by hypercapnia (vs. normoxia, P < 0.05) but remained unchanged under ACZ (vs. placebo). V˙E peak power was positively related to cardiac output (Q˙c) and V˙E in hyperoxia (P < 0.01), in hypercapnia (P < 0.001) and under ACZ (P < 0.001). V˙E period was negatively related to Q˙c and V˙E in hyperoxia (P < 0.01 and P < 0.001, respectively), in hypercapnia (P < 0.05 and P < 0.01, respectively) and under ACZ (P < 0.05 and P < 0.01, respectively). Total respiratory cycle time was the main factor responsible for changes in V˙E period. In conclusion, exercise, hypoxia, and hypercapnia increase ventilatory oscillations by increasing Q˙c and V˙E, whereas ACZ decreases ventilatory instability in part by a contrasting action on O2 and CO2 sensing. An intrinsic oscillator might modulate ventilation through a complex system where peripheral chemoreflex would play a key role. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

Impaired ventilatory acclimatization to hypoxia in female mice overexpressing erythropoietin: unexpected deleterious effect of estradiol in carotid bodies.

PubMed

Gassmann, Max; Pfistner, Christine; Doan, Van Diep; Vogel, Johannes; Soliz, Jorge

2010-12-01

Apart from enhancing the production of red blood cells, erythropoietin (Epo) alters the ventilatory response when oxygen supply is reduced. We recently demonstrated that Epo's beneficial effect on the ventilatory response to acute hypoxia is sex dependent, with female mice being better able to cope with reduced oxygenation. In the present work, we hypothesized that ventilatory acclimatization to chronic hypoxia (VAH) in transgenic female mice (Tg6) harboring high levels of Epo in the brain and blood will also be improved compared with wild-type (WT) animals. Surprisingly, VAH was blunted in Tg6 female mice. To define whether this phenomenon had a central (brain stem respiratory centers) and/or peripheral (carotid bodies) origin, a bilateral transection of carotid sinus nerve (chemodenervation) was performed. This procedure allowed the analysis of the central response in the absence of carotid body information. Interestingly, chemodenervation restored the VAH in Tg6 mice, suggesting that carotid bodies were responsible for the blunted response. Coherently with this observation, the sensitivity to oxygen alteration in arterial blood (Dejour test) after chronic hypoxia was lower in transgenic carotid bodies compared with the WT control. As blunted VAH occurred in female but not male transgenic mice, the involvement of sex female steroids was obvious. Indeed, measurement of sexual female hormones revealed that the estradiol serum level was 4 times higher in transgenic mice Tg6 than in WT animals. While ovariectomy decreased VAH in WT females, this treatment restored VAH in Tg6 female mice. In line with this observation, injections of estradiol in ovariectomized Tg6 females dramatically reduced the VAH. We concluded that during chronic hypoxia, estradiol in carotid bodies suppresses the Epo-mediated elevation of ventilation. Considering the increased application of recombinant Epo for a variety of disorders, our data imply the need to take the patient's hormonal status into consideration.

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.

[Competitive study of the effects of naloxone and of almitrine on fentanyl analgesia in the anesthetized dog: effects on the muzzle opening reflex and blood gases].

PubMed

Dauthier, C; Gaudy, J H; Willer, J C

1980-01-01

The search for a technique making it possible to dissociate the analgesia and ventilatory depression of central analgesics led to a comparison of the effects of naloxone, a specific morphinomimetic antagonist, with almitrine, a ventilatory stimulant with a peripheral action, on muzzle opening reflex and blood gases. Five male dogs (Beagles, aged one year), anaesthetised with Alfetesine were treated separately with the two drugs used alone and after fentanyl analgesia (injection of fractionnated doses up to the threshold of apnoea). The association of the two drugs was also tested in tyhe dog after analgesia. The parameters studied were muzzle opening reflex, as an indication of analgesia, and blood gases, and were observed for 45 minutes, including 15 minutes control. 1 - The intravenous injection of 1,2 mg of naloxone had the effect of increasing the surface area of muscle potentials with a maximum of 7 per cent (p 0.001) at the 15 th minute. By contrast, no significant change in blood gases was seen. In the same dogs given fentanyl analgesia, naloxone not only reversed respiratory depression but had a stimulatory effect on MOR reaching 7 per cent (p 0.001) at the 30 th minute. 2 - The effects of 1 mg.kg-1 of almitrine were characterised by a fall in MOR for a period equal to that of the study and a minimum of 7.8 per cent (p 0.001) at the 20 th minute. At the same time, marked ventilatory stimulation was seen. PO2 rose by 22.7 per cent (p 0.02) at the 5 th minute. PCO2 fell during the 30 minutes studied with a minimum of 39.6 per cent (p 0.01) at the 20 th minute. Almitrine did not antagonise the depression of MOR caused by fentanyl but reversed the respiratory depression of the analgesic, increasing PO2 by 26 per cent (p 0.01) and decreasing PCO2 by 25.7 per cent (p 0.01). 3 - The combination of both drugs cancelled out the abolition of the reflex by fentanyl then facilitated it up to 24.7 per cent (p 0.001) in comparison with the animal not receiving any analgesic. By contrast, the ventilatory action of almitrine was not potentialised by naloxone. In view of these data, and in the absence of any emergency, the choice of naloxone as an antagonist of ventilatory depression of central analgesics should not be preferential in order to avoid the rebound effect.

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.

Heat and moisture exchanger: importance of humidification in anaesthesia and ventilatory breathing system.

PubMed

Parmar, Vandana

2008-08-01

Adequate humidification is vital to maintain homeostasis of the airway. Heat and moisture exchangers conserve some of the exhaled water, heat and return them to inspired gases. Many heat and moisture exchangers also perfom bacterial/viral filtration and prevent inhalation of small particles. Heat and moisture exchangers are also called condenser humidifier, artificial nose, etc. Most of them are disposable devices with exchanging medium enclosed in a plastic housing. For adult and paediatric age group different dead space types are available. Heat and moisture exchangers are helpful during anaesthesia and ventilatory breathing system. To reduce the damage of the upper respiratory tract through cooling and dehydration inspiratory air can be heated and humidified, thus preventing the serious complications.

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.

Home mechanical ventilation in Canada: a national survey.

PubMed

Rose, Louise; McKim, Douglas A; Katz, Sherri L; Leasa, David; Nonoyama, Mika; Pedersen, Cheryl; Goldstein, Roger S; Road, Jeremy D

2015-05-01

No comprehensive Canadian national data describe the prevalence of and service provision for ventilator-assisted individuals living at home, data critical to health-care system planning for appropriate resourcing. Our objective was to generate national data profiling service providers, users, types of services, criteria for initiation and monitoring, ventilator servicing arrangements, education, and barriers to home transition. Eligible providers delivering services to ventilator-assisted individuals (adult and pediatric) living at home were identified by our national provider inventory and referrals from other providers. The survey was administered via a web link from August 2012 to April 2013. The survey response rate was 152/171 (89%). We identified 4,334 ventilator-assisted individuals: an estimated prevalence of 12.9/100,000 population, with 73% receiving noninvasive ventilation (NIV) and 18% receiving intermittent mandatory ventilation (9% not reported). Services were delivered by 39 institutional providers and 113 community providers. We identified variation in initiation criteria for NIV, with polysomnography demonstrating nocturnal hypoventilation (57%), daytime hypercapnia (38%), and nocturnal hypercapnia (32%) as the most common criteria. Various models of ventilator servicing were reported. Most providers (64%) stated that caregiver competency was a prerequisite for home discharge; however, repeated competency assessment and retraining were offered by only 45%. Important barriers to home transition were: insufficient funding for paid caregivers, equipment, and supplies; a shortage of paid caregivers; and negotiating public funding arrangements. Ventilatory support in the community appears well-established, with most individuals managed with NIV. Although caregiver competency is a prerequisite to discharge, ongoing assessment and retraining were infrequent. Funding and caregiver availability were important barriers to home transition. Copyright © 2015 by Daedalus Enterprises.

Contributors to fatigue in patients receiving mechanical ventilatory support: A descriptive correlational study.

PubMed

Chlan, Linda L; Savik, Kay

2015-10-01

To describe levels of fatigue and explore clinical factors that might contribute to fatigue in critically ill patients receiving mechanical ventilation. Descriptive, correlational design. Sample was a sub-set of patients enrolled in a randomised clinical trial testing patient-directed music for anxiety self-management. Clinical factors included age, gender, length of ICU stay, length of ventilatory support, illness severity (APACHE III), and sedative exposure (sedation intensity and frequency). Descriptive statistics and mixed models were used to address the study objectives. Medical and surgical intensive care units in the Midwestern United States. Fatigue was measured daily via a 100-mm Visual Analogue Scale, up to 25 days. A sample of 80 patients (50% female) receiving ventilatory support for a median 7.9 days (range 1-46) with a mean age of 61.2 years (SD 14.8) provided daily fatigue ratings. ICU admission APACHE III was 61.5 (SD 19.8). Baseline mean fatigue ratings were 60.7 (SD 27.9), with fluctuations over time indicating a general trend upward. Mixed models analysis implicated illness severity (β(se(β))=.27(.12)) and sedation frequency (β(se(β))=1.2(.52)) as significant contributors to fatigue ratings. Illness severity and more frequent sedative administration were related to higher fatigue ratings in these mechanically ventilated patients. Copyright © 2015 Elsevier Ltd. All rights reserved.

CONTRIBUTORS TO FATIGUE IN PATIENTS RECEIVING MECHANICAL VENTILATORY SUPPORT: A DESCRIPTIVE CORRELATIONAL STUDY

PubMed Central

Chlan, Linda L.; Savik, Kay

2015-01-01

Objectives To describe levels of fatigue and explore clinical factors that might contribute to fatigue in critically ill patients receiving mechanical ventilation. Research Methodology/Design Descriptive, correlational design. Sample was a sub-set of patients enrolled in a randomized clinical trial testing patient-directed music for anxiety self-management. Clinical factors included age, gender, length of ICU stay, length of ventilatory support, illness severity (APACHE III), and sedative exposure (sedation intensity and frequency). Descriptive statistics and mixed models were used to address the study objectives. Setting Medical and surgical intensive care units in the Midwestern U.S.A. Main Outcome Measures Fatigue was measured daily via a 100-mm Visual Analog Scale, up to 25 days. Results A sample of 80 patients (50% female) receiving ventilatory support for a median 7.9 days (range 1-46) with a mean age of 61.2 years (SD 14.8) provided daily fatigue ratings. ICU admission APACHE III was 61.5 (SD 19.8). Baseline mean fatigue ratings were 60.7 (SD 27.9), with fluctuations over time indicating a general trend upward. Mixed models analysis implicated illness severity (β(se(β)) = .27(.12)) and sedation frequency (β(se(β)) = 1.2(.52)) as significant contributors to fatigue ratings. Conclusion Illness severity and more frequent sedative administration were related to higher fatigue ratings in these mechanically ventilated patients. PMID:26005034

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.

Ionotropic but not metabotropic glutamatergic receptors in the locus coeruleus modulate the hypercapnic ventilatory response in unanaesthetized rats.

PubMed

Taxini, C L; Puga, C C I; Dias, M B; Bícego, K C; Gargaglioni, L H

2013-05-01

Central chemoreceptors are important to detect changes of CO2/H(+), and the Locus coeruleus (LC) is one of the many putative central chemoreceptor sites. Here, we studied the contribution of LC glutamatergic receptors on ventilatory, cardiovascular and thermal responses to hypercapnia. To this end, we determined pulmonary ventilation (V(E)), body temperatures (T(b)), mean arterial pressure (MAP) and heart rate (HR) of male Wistar rats before and after unilateral microinjection of kynurenic acid (KY, an ionotropic glutamate receptor antagonist, 10 nmol/0.1 μL) or α-methyl-4-carboxyphenylglycine (MCPG, a metabotropic glutamate receptor antagonist, 10 nmol/0.1 μL) into the LC, followed by 60 min of air breathing or hypercapnia exposure (7% CO2). Ventilatory response to hypercapnia was higher in animals treated with KY intra-LC (1918.7 ± 275.4) compared with the control group (1057.8 ± 213.9, P < 0.01). However, the MCPG treatment within the LC had no effect on the hypercapnia-induced hyperpnea. The cardiovascular and thermal controls were not affected by hypercapnia or by the injection of KY and MCPG in the LC. These data suggest that glutamate acting on ionotropic, but not metabotropic, receptors in the LC exerts an inhibitory modulation of hypercapnia-induced hyperpnea. Acta Physiologica © 2013 Scandinavian Physiological Society.

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.

Ventilatory responses to exercise training in obese adolescents.

PubMed

Mendelson, Monique; Michallet, Anne-Sophie; Estève, François; Perrin, Claudine; Levy, Patrick; Wuyam, Bernard; Flore, Patrice

2012-10-15

The aim of this study was to examine ventilatory responses to training in obese adolescents. We assessed body composition, pulmonary function and ventilatory responses (among which expiratory flow limitation and operational lung volumes) during progressive cycling exercise in 16 obese adolescents (OB) before and after 12 weeks of exercise training and in 16 normal-weight volunteers. As expected, obese adolescents' resting expiratory reserve volume was lower and inversely correlated with thoraco-abdominal fat mass (r = -0.74, p<0.0001). OB presented lower end expiratory (EELV) and end inspiratory lung volumes (EILV) at rest and during submaximal exercise, and modest expiratory flow limitation. After training, OB increased maximal aerobic performance (+19%) and maximal inspiratory pressure (93.7±31.4 vs. 81.9±28.2 cm H2O, +14%) despite lack of decrease in trunk fat and body weight. Furthermore, EELV and EILV were greater during submaximal exercise (+11% and +9% in EELV and EILV, respectively), expiratory flow limitation delayed but was not accompanied by increased V(T). However, submaximal exertional symptoms (dyspnea and leg discomfort) were significantly decreased (-71.3% and -70.7%, respectively). Our results suggest that exercise training can improve pulmonary function at rest (static inspiratory muscle strength) and exercise (greater operating lung volumes and delayed expiratory flow limitation) but these modifications did not entirely account for improved dyspnea and exercise performance in obese adolescents. Copyright © 2012 Elsevier B.V. All rights reserved.

Hypopnea consequent to reduced pulmonary blood flow in the dog.

PubMed

Stremel, R W; Whipp, B J; Casaburi, R; Huntsman, D J; Wasserman, K

1979-06-01

The ventilatory responses to diminished pulmonary blood flow (Qc), as a result of partial cardiopulmonary bypass (PCB), were studied in chloralose-urethan-anesthetized dogs. Qc was reduced by diverting vena caval blood through a membrane gas exchanger and returning it to the ascending aorta. PCB flows of 400--1,600 ml/min were utilized for durations of 2--3 min. Decreasing Qc, while maintaining systemic arterial blood gases and perfusion, results in a significant (P less than 0.05) decrease in expiratory ventilation (VE) (15.9%) and alveolar ventilation (VA) (31.0%). The ventilatory decreases demonstrated for this intact group persist after bilateral cervical vagotomy (Vx), carotid body and carotid sinus denervation (Cx), and combined Vx and Cx. The changes in VE and VA were significantly (P less than 0.001) correlated with VCO2 changes, r = 0.80 and r = 0.93, respectively. These ventilatory changes were associated with an overall average decrease in left ventricular PCO2 of 2.1 Torr; this decrease was significant (P less than 0.05) only in the intact and Cx groups. Decreasing pulmonary blood flow results in a decrease in ventilation that may be CO2 related; however, the exact mechanism remains obscure but must have a component that is independent of vagally mediated cardiac and pulmonary afferents and peripheral baroreceptor and chemoreceptor afferents.

Anaerobic Threshold by Mathematical Model in Healthy and Post-Myocardial Infarction Men.

PubMed

Novais, L D; Silva, E; Simões, R P; Sakabe, D I; Martins, L E B; Oliveira, L; Diniz, C A R; Gallo, L; Catai, A M

2016-02-01

The aim of this study was to determine the anaerobic threshold (AT) in a population of healthy and post-myocardial infarction men by applying Hinkley's mathematical method and comparing its performance to the ventilatory visual method. This mathematical model, in lieu of observer-dependent visual determination, can produce more reliable results due to the uniformity of the procedure. 17 middle-aged men (55±3 years) were studied in 2 groups: 9 healthy men (54±2 years); and 8 men with previous myocardial infarction (57±3 years). All subjects underwent an incremental ramp exercise test until physical exhaustion. Breath-by-breath ventilatory variables, heart rate (HR), and vastus lateralis surface electromyography (sEMG) signal were collected throughout the test. Carbon dioxide output (V˙CO2), HR, and sEMG were studied, and the AT determination methods were compared using correlation coefficients and Bland-Altman plots. Parametric statistical tests were applied with significance level set at 5%. No significant differences were found in the HR, sEMG, and ventilatory variables at AT between the different methods, such as the intensity of effort relative to AT. Moreover, important concordance and significant correlations were observed between the methods. We concluded that the mathematical model was suitable for detecting the AT in both healthy and myocardial infarction subjects. © Georg Thieme Verlag KG Stuttgart · New York.

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.

Fatty acid amide hydrolase-morphine interaction influences ventilatory response to hypercapnia and postoperative opioid outcomes in children.

PubMed

Chidambaran, Vidya; Pilipenko, Valentina; Spruance, Kristie; Venkatasubramanian, Raja; Niu, Jing; Fukuda, Tsuyoshi; Mizuno, Tomoyuki; Zhang, Kejian; Kaufman, Kenneth; Vinks, Alexander A; Martin, Lisa J; Sadhasivam, Senthilkumar

2017-01-01

Fatty acid amide hydrolase (FAAH) degrades anandamide, an endogenous cannabinoid. We hypothesized that FAAH variants will predict risk of morphine-related adverse outcomes due to opioid-endocannabinoid interactions. In 101 postsurgical adolescents receiving morphine analgesia, we prospectively studied ventilatory response to 5% CO 2 (HCVR), respiratory depression (RD) and vomiting. Blood was collected for genotyping and morphine pharmacokinetics. We found significant FAAH-morphine interaction for missense (rs324420) and several regulatory variants, with HCVR (p < 0.0001) and vomiting (p = 0.0339). HCVR was more depressed in patients who developed RD compared with those who did not (p = 0.0034), thus FAAH-HCVR association predicts risk of impending RD from morphine use. FAAH genotypes predict risk for morphine-related adverse outcomes.

Non-invasive ventilation for cancer patients with life-support techniques limitation.

PubMed

Meert, Anne-Pascale; Berghmans, Thierry; Hardy, Michel; Markiewicz, Eveline; Sculier, Jean-Paul

2006-02-01

The study was conducted to determine the usefulness and efficacy of non-invasive ventilation (NIV) in cancer patients with "life-support techniques limitation" admitted for an acute respiratory distress, in terms of intensive care unit (ICU) and hospital discharges. A total of 18 consecutive cancer patients (17 with solid tumours and one with haematological malignancy) with "life-support techniques limitation" in acute respiratory failure and who benefited from NIV were included. NIV was provided with a standard face mask by the BiPAP Vision ventilator (Respironics Inc.). Variables related to the demographic parameters, SAPS II score, cancer characteristics, intensive care data and hospital discharge were recorded. Complications leading to NIV were hypoxemic respiratory failure in 11 patients and hypercapnic respiratory failure in seven. Total median duration of NIV was 29 h. NIV was applied during a median of 2.5 days with a median of 16 h per day. Total median ICU stay was 7 days (range 1-21). Fourteen and ten patients were discharged from ICU and from hospital, respectively. NIV appears to be an effective ventilation support for cancer patients with "life-support techniques limitation".

Hypothyroid Graves' disease complicated with elephantiasis nostras verrucosa (ENV): a case report and review of the literature.

PubMed

Ukinç, Kubilay; Bayraktar, Miyase; Gedik, Arzu

2009-08-01

Thyroid dermopathy is not a frequent feature of hyperthyroid Graves' disease, being present in less than 5% of the patients. Graves' disease has been shown to exist in euthyroid or hypothyroid forms in untreated patients. Here, we describe a case of hypothyroid Graves' disease with elephantiasis nostras verrucosa (ENV), which is an extreme form of thyroid dermopathy (TD). A 58-year-old female patient was admitted to the emergency department with somnolence, hypothermia, and bradycardia. Her mental status gradually worsened, resulting in a deep coma. She was intubated and followed in the intensive care unit, as she needed mechanical ventilatory assistance due to respiratory failure. She also had bilateral non-pitting edema, a cobblestone-like appearance, and hyperkeratotic greenish-brown-colored lesions in the pretibial and dorsal regions of the feet that were compatible with ENV. Hypothyroid Graves' disease is a very rare condition among autoimmune thyroid disorders, and ENV is an extremely rare form of TD. Here, we present a patient with hypothyroid Graves' disease and ENV.

Mechanical ventilation for severe asthma.

PubMed

Leatherman, James

2015-06-01

Acute exacerbations of asthma can lead to respiratory failure requiring ventilatory assistance. Noninvasive ventilation may prevent the need for endotracheal intubation in selected patients. For patients who are intubated and undergo mechanical ventilation, a strategy that prioritizes avoidance of ventilator-related complications over correction of hypercapnia was first proposed 30 years ago and has become the preferred approach. Excessive pulmonary hyperinflation is a major cause of hypotension and barotrauma. An appreciation of the key determinants of hyperinflation is essential to rational ventilator management. Standard therapy for patients with asthma undergoing mechanical ventilation consists of inhaled bronchodilators, corticosteroids, and drugs used to facilitate controlled hypoventilation. Nonconventional interventions such as heliox, general anesthesia, bronchoscopy, and extracorporeal life support have also been advocated for patients with fulminant asthma but are rarely necessary. Immediate mortality for patients who are mechanically ventilated for acute severe asthma is very low and is often associated with out-of-hospital cardiorespiratory arrest before intubation. However, patients who have been intubated for severe asthma are at increased risk for death from subsequent exacerbations and must be managed accordingly in the outpatient setting.

VO2max and ventilatory threshold of trained cyclists are not affected by 28-day L-arginine supplementation.

PubMed

Sunderland, Kyle L; Greer, Felicia; Morales, Jacobo

2011-03-01

The ergogenic effect of L-arginine on an endurance-trained population is not well studied. The few studies that have investigated L-arginine on this population have not been conducted in a laboratory setting or measured aerobic variables. The purpose of the current study is to determine if 28 days of L-arginine supplementation in trained male cyclists affects VO2max and ventilatory threshold (VT). Eighteen (18) endurance-trained male cyclists (mean ± SD, age: 36.3 ± 7.9 years; height: 182.4 ± 4.6 cm; and body mass: 79.5 ± 4.7 kg) performed a graded exercise test (GXT; 50 W + 25 W·min) before and after 28 days of supplementation with L-arginine (ARG; 2 × 6 g·d) or placebo (PLA; cornstarch). The GXT was conducted on the subject's own bicycle using the RacerMate CompuTrainer (Seattle, WA, USA). VO2 was continuously recorded using the ParvoMedics TrueOne 2400 metabolic cart (Salt Lake City, UT, USA) and VT was established by plotting the ventilatory equivalent for O2 (VE/VO2) and the ventilatory equivalent for CO2 (VE/VCO2) and identifying the point at which VE/VO2 increases with no substantial changes in VE/VCO2. L-arginine supplementation had no effect from initial VO2max (PL, 58.7 ± 7.1 ml·kg·min; ARG, 63.5 ± 7.3 ml·kg·min) to postsupplement VO2max (PL, 58.9 ± 6.0 ml·kg·min; ARG, 63.2 ± 7.2 ml·kg·min). Also, no effect was seen from initial VT (PL, 75.7 ± 4.6% VO2max; ARG, 76.0 ± 5.3% VO2max) to postsupplement VT (PL, 74.3 ± 8.1% VO2max; ARG, 74.2 ± 6.4% VO2max). These results indicate that L-arginine does not impact VO2max or VT in trained male cyclists.

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.

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.

From the Cover: Prenatal Nicotinic Exposure Attenuates Respiratory Chemoreflexes Associated With Downregulation of Tyrosine Hydroxylase and Neurokinin 1 Receptor in Rat Pup Carotid Body.

PubMed

Zhao, Lei; Zhuang, Jianguo; Gao, Xiuping; Ye, Chunyan; Lee, Lu-Yuan; Xu, Fadi

2016-09-01

Maternal cigarette smoke is the major risk of sudden infant death syndrome (SIDS). A depressed ventilatory response to hypoxia (HVR) and hypercapnia (HCVR) is thought to be responsible for the pathogenesis of SIDS and the carotid body is critically involved in these responses. We have recently reported that prenatal nicotinic exposure (PNE) over the full gestation induces depressed HVR in rat pups. Here, we asked whether PNE (1) depressed not only HVR but also HCVR that were dependent on the carotid body, (2) affected some important receptors and neurochemicals expressed in the carotid body, such as tyrosine hydroxylase (TH), neurokinin-1 receptor (NK1R), and α7 nicotinic acetylcholine receptor (α7nAChR), and (3) blunted the ventilatory responses to activation of these receptors. To this end, HVR and HCVR in Ctrl and PNE pups were measured with plethysmography before and after carotid body ablation (Series I), mRNA expression and/or immunoreactivity (IR) of TH, NK1R, and α7nAChR in the carotid body were examined by RT-PCR and immunohistochemistry (Series II), and the ventilatory responses were tested before and after intracarotid injection of substance P (NK1R agonist) and AR-R17779 (α7nAChR agonist) (Series III). Our results showed that PNE (1) significantly depressed both HVR and HCVR and these depressions were abolished by carotid body ablation, (2) reduced the relative population of glomus cells, mRNA NK1R, and α7nAChR and IR of NK1R and TH in the carotid body, and (3) decreased ventilatory responses to intracarotid injection of substance P or AR-R17779. These results suggest that PNE acting via the carotid body could strikingly blunt HVR and HCVR, likely through downregulating TH and NK1R. © The Author 2016. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

21 CFR 868.1850 - Monitoring spirometer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... of gas inhaled by the patient during each respiration cycle) or minute volume (the tidal volume multiplied by the rate of respiration for 1 minute) for the evaluation of the patient's ventilatory status...

21 CFR 868.1850 - Monitoring spirometer.

Code of Federal Regulations, 2010 CFR

2010-04-01

... of gas inhaled by the patient during each respiration cycle) or minute volume (the tidal volume multiplied by the rate of respiration for 1 minute) for the evaluation of the patient's ventilatory status...

Fatty acid amide hydrolase–morphine interaction influences ventilatory response to hypercapnia and postoperative opioid outcomes in children

PubMed Central

Chidambaran, Vidya; Pilipenko, Valentina; Spruance, Kristie; Venkatasubramanian, Raja; Niu, Jing; Fukuda, Tsuyoshi; Mizuno, Tomoyuki; Zhang, Kejian; Kaufman, Kenneth; Vinks, Alexander A; Martin, Lisa J; Sadhasivam, Senthilkumar

2017-01-01

Aim: Fatty acid amide hydrolase (FAAH) degrades anandamide, an endogenous cannabinoid. We hypothesized that FAAH variants will predict risk of morphine-related adverse outcomes due to opioid–endocannabinoid interactions. Patients & methods: In 101 postsurgical adolescents receiving morphine analgesia, we prospectively studied ventilatory response to 5% CO2 (HCVR), respiratory depression (RD) and vomiting. Blood was collected for genotyping and morphine pharmacokinetics. Results: We found significant FAAH–morphine interaction for missense (rs324420) and several regulatory variants, with HCVR (p < 0.0001) and vomiting (p = 0.0339). HCVR was more depressed in patients who developed RD compared with those who did not (p = 0.0034), thus FAAH–HCVR association predicts risk of impending RD from morphine use. Conclusion: FAAH genotypes predict risk for morphine-related adverse outcomes. PMID:27977335

[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.

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.

Respiratory disability in coal miners

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

Morgan, W.K.C.; Lapp, N.L.; Seaton, D.

1980-06-20

It has been suggested that the assessment of ventilatory capacity alone is inadequate for the determination of disabling occupational respiratory impairment in coal miners. The Department of Labor has accepted this view and now routinely requests blood gas analyses in those claimants not meeting the ventilatory criteria. We tested the validity of this contention by selecting two groups of coal miners claiming total disability. The first consisted of 150 claimants who were referred for spirometry, while the second consisted of 50 claimants who had been referred for blood gas studies. Of those in group 1, eight met the extant criteriamore » for disability, while only two of those in group 2 satisfied the criteria, and, in both, cardiac disease was responsible. We conclude that blood gas analyses are unnecessary in the determination of pulmonary disability in coal miners.« less

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.

Anaesthetic management of sleep-disordered breathing in adults.

PubMed

Hillman, David R; Chung, Frances

2017-02-01

Anaesthesia and sleep are different states of unconsciousness with considerable physiological common ground. Because of their shared depressant effects on muscle activation and ventilatory drive, patients with anatomically compromised airways will tend to obstruct in either state and those with impaired ventilatory capacity will tend to hypoventilate. Breathing behaviour in one state is predictive of that in the other. An essential difference is that while arousal responses are preserved during sleep, they are depressed during sedation and abolished by anaesthesia. This renders patients with sleep-related breathing disorders vulnerable to hypoventilation and asphyxia when deeply sedated. Addressing this vulnerability requires a systematic approach to identification of patients and circumstances that magnify this risk, and methods of managing it that seek to reconcile the need for safety with cost-effective use of resources. © 2016 Asian Pacific Society of Respirology.

Behavioral, Ventilatory and Thermoregulatory Responses to Hypercapnia and Hypoxia in the Wistar Audiogenic Rat (WAR) Strain

PubMed Central

Giusti, Humberto; Oliveira, José Antonio; Glass, Mogens Lesner; Garcia-Cairasco, Norberto

2016-01-01

Introduction We investigated the behavioral, respiratory, and thermoregulatory responses elicited by acute exposure to both hypercapnic and hypoxic environments in Wistar audiogenic rats (WARs). The WAR strain represents a genetic animal model of epilepsy. Methods Behavioral analyses were performed using neuroethological methods, and flowcharts were constructed to illustrate behavioral findings. The body plethysmography method was used to obtain pulmonary ventilation (VE) measurements, and body temperature (Tb) measurements were taken via temperature sensors implanted in the abdominal cavities of the animals. Results No significant difference was observed between the WAR and Wistar control group with respect to the thermoregulatory response elicited by exposure to both acute hypercapnia and acute hypoxia (p>0.05). However, we found that the VE of WARs was attenuated relative to that of Wistar control animals during exposure to both hypercapnic (WAR: 133 ± 11% vs. Wistar: 243 ± 23%, p<0.01) and hypoxic conditions (WAR: 138 ± 8% vs. Wistar: 177 ± 8%; p<0.01). In addition, we noted that this ventilatory attenuation was followed by alterations in the behavioral responses of these animals. Conclusions Our results indicate that WARs, a genetic model of epilepsy, have important alterations in their ability to compensate for changes in levels of various arterial blood gasses. WARs present an attenuated ventilatory response to an increased PaCO2 or decreased PaO2, coupled to behavioral changes, which make them a suitable model to further study respiratory risks associated to epilepsy. PMID:27149672

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.

Resolution of exercise oscillatory ventilation with adaptive servoventilation in patients with chronic heart failure and Cheyne-Stokes respiration: preliminary study.

PubMed

Kazimierczak, Anna; Krzyżanowski, Krystian; Wierzbowski, Robert; Ryczek, Robert; Smurzyński, Paweł; Michałkiewicz, Dariusz; Orski, Zbigniew; Gielerak, Grzegorz

2011-01-01

Exercise oscillatory ventilation (EOV) is a common pattern of breathing in heart failure (HF) patients, and indicates a poor prognosis. To investigate the effects of adaptive servoventilation (ASV) on ventilatory response during exercise. We studied 39 HF patients with left ventricular ejection fraction (LVEF) £ 45. Cardiorespiratory polygraphy, cardiopulmonary exercise testing (CPET), echocardiography, and measurement of N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration were performed. Twenty patients with Cheyne-Stokes respiration and apnoea-hypopnoea index (AHI) ≥ 15/h were identified. Of these, 11 patients were successfully titrated on ASV and continued therapy. In the third month of ASV treatment, polygraphy, CPET, echocardiography, and measurement of NT-proBNP concentration were performed again. The EOV was detected at baseline in 12 (31%) HF patients, including eight (67%) who underwent ASV. The EOV was associated with significantly lower LVEF, peak oxygen uptake (VO(2)), and ventilatory anaerobic threshold (VAT), and a significantly higher left ventricular diastolic diameter (LVDD), slope of ventilatory equivalent for carbon dioxide (VE/VCO(2)), AHI, central AHI and NT-proBNP concentration. In seven patients with EOV, reversal of EOV in the third month of ASV therapy was observed; only in one patient did EOV persist (p = 0.0156). The EOV can be reversed with ASV therapy. The EOV in association with central sleep apnoea and Cheyne- -Stokes respiration (CSA/CSR) is prevalent in HF patients and correlates with severity of the disease.

Voluntary respiratory control and cerebral blood flow velocity upon ice-water immersion.

PubMed

Mantoni, Teit; Rasmussen, Jakob Højlund; Belhage, Bo; Pott, Frank Christian

2008-08-01

In non-habituated subjects, cold-shock response to cold-water immersion causes rapid reduction in cerebral blood flow velocity (approximately 50%) due to hyperventilation, increasing risk of syncope, aspiration, and drowning. Adaptation to the response is possible, but requires several cold immersions. This study examines whether thorough instruction enables non-habituated persons to attenuate the ventilatory component of cold-shock response. There were nine volunteers (four women) who were lowered into a 0 degrees C immersion tank for 60 s. Middle cerebral artery mean velocity (CBFV) was measured together with ventilatory parameters and heart rate before, during, and after immersion. Within seconds after immersion in ice-water, heart rate increased significantly from 95 +/- 8 to 126 +/- 7 bpm (mean +/- SEM). Immersion was associated with an elevation in respiratory rate (from 12 +/- 3 to 21 +/- 5 breaths, min(-1)) and tidal volume (1022 +/- 142 to 1992 +/- 253 ml). Though end-tidal carbon dioxide tension decreased from 4.9 +/- 0.13 to 3.9 +/- 0.21 kPa, CBFV was insignificantly reduced by 7 +/- 4% during immersion with a brief nadir of 21 +/- 4%. Even without prior cold-water experience, subjects were able to suppress reflex hyperventilation following ice-water immersion, maintaining the cerebral blood flow velocity at a level not associated with impaired consciousness. This study implies that those susceptible to accidental cold-water immersion could benefit from education in cold-shock response and the possibility of reducing the ventilatory response voluntarily.

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.

Ventilatory, metabolic, and thermal responses to hypercapnia in female rats: effects of estrous cycle, ovariectomy, and hormonal replacement.

PubMed

Marques, Danuzia A; de Carvalho, Débora; da Silva, Glauber S F; Szawka, Raphael E; Anselmo-Franci, Janete A; Bícego, Kênia C; Gargaglioni, Luciane H

2015-07-01

The aim of this study was to examine how estrous cycle, ovariectomy, and hormonal replacement affect the respiratory [ventilation (V̇e), tidal volume, and respiratory frequency], metabolic (V̇o2), and thermoregulatory (body temperature) responses to hypercapnia (7% CO2) in female Wistar rats. The parameters were measured in rats during different phases of the estrous cycle, and also in ovariectomized (OVX) rats supplemented with 17β-estradiol (OVX+E2), with a combination of E2 and progesterone (OVX+E2P), or with corn oil (OVX+O, vehicle). All experiments were conducted on day 8 after ovariectomy. The intact animals did not present alterations during normocapnia or under hypercapnia in V̇e, tidal volume, respiratory frequency, V̇o2, and V̇e/V̇o2 in the different phases of the estrous cycle. However, body temperature was higher in female rats on estrus. Hormonal replacement did not change the ventilatory, thermoregulatory, or metabolic parameters during hypercapnia, compared with the OVX animals. Nevertheless, OVX+E2, OVX+E2P, and OVX+O presented lower hypercapnic ventilatory responses compared with intact females on the day of estrus. Also, rats in estrus showed higher V̇e and V̇e/V̇o2 during hypercapnia than OVX animals. The data suggest that other gonadal factors, besides E2 and P, are possibly involved in these responses. Copyright © 2015 the American Physiological Society.

Hypothyroidism Attenuates SCH 23390-mediated Depression of Breathing and Decreases D1 Receptor Expression in Carotid Bodies, PVN and Striatum of Hamsters

PubMed Central

Schlenker, Evelyn H.; Schultz, Harold D.

2011-01-01

Hypothyroidism can lead to depressed breathing. We determined if propylthiouracil (PTU)–induced hypothyroidism in hamsters (HH) altered dopamine D1 receptor expression, D1 receptor-modulated ventilation, and ventilatory chemoreflex activation by hypoxia or hypercapnia. Hypothyroidism was induced by administering 0.04% PTU in drinking water for three months. Ventilation was evaluated following saline or 0.25 mg/kg SCH 23390, a D1 receptor antagonist, while awake hamsters breathed normoxic (21% O2 in N2), hypoxic (10% O2 in N2) and hypercapnic (5% CO2 in O2) air. Relative to euthyroid hamsters (EH), HH exhibited decreased D1 receptor protein levels in carotid bodies, striatum, and hypothalamic paraventricular nucleus, but not in the nucleus tractus solitarius. Relative to EH, HH exhibited lower ventilation during exposure to normoxia, hypoxia, or hypercapnia, but comparable ventilatory responsiveness to chemoreflex activation. SCH 23390 decreased ventilation of EH hamsters exposed to normoxia, hypoxia, and hypercapnia. In HH SCH 23390 increased ventilation during baseline normoxia and did not affect ventilation during exposure to hypoxia and hypercapnia, resulting in reduced ventilatory responsivess to chemoreflex activation by hypoxia and hypercapnia. Furthermore, in HH D1 receptor protein levels are decreased in several brain regions and within the carotid bodies. Moreover, D1 receptor-modulation of breathing at rest and during gas exposures were depressed in EH but not HH. PMID:21669406

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 .

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.

Impaired acclimatization to chronic hypoxia in adult male and female rats following neonatal hypoxia.

PubMed

Lumbroso, Delphine; Joseph, Vincent

2009-08-01

We tested the hypothesis that neonatal exposure to hypoxia alters acclimatization to chronic hypoxia later in life. Rat pups were exposed to normobaric hypoxia (12% O(2); nHx group) in a sealed chamber, or to normoxia (21% O(2); nNx group) from the day before birth to postnatal day 10. The animals were then raised in normal conditions until reaching 12 wk of age. At this age, we assessed ventilatory and hematological acclimatization to chronic hypoxia by exposing male and female nHx and nNx rats for 2 wk to 10% O(2). Minute ventilation, metabolic rate, hypoxic ventilatory response, hematocrit, and hemoglobin levels were measured both before and after acclimatization. We also quantified right ventricular hypertrophy as an index of pulmonary hypertension both before and after acclimatization. There was a significant effect of neonatal hypoxia that decreases ventilatory response (relative to metabolic rate, VE/VCO(2)) to acute hypoxia before acclimatization in males but not in females. nHx rats had an impaired acclimatization to chronic hypoxia characterized by altered respiratory pattern and elevated hematocrit and hemoglobin levels after acclimatization, in both males and females. Right ventricular hypertrophy was present before and after acclimatization in nHx rats, indicating that neonatal hypoxia results in pulmonary hypertension in adults. We conclude that neonatal hypoxia impairs acclimatization to chronic hypoxia in adults and may be a factor contributing to the establishment of chronic mountain sickness in humans living at high altitude.

21 CFR 898.13 - Compliance dates.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Frequency. 1 73 FLS 868.2375 II Monitor (Apnea Detector), Ventilatory Effort. 1 74 DPS 870.2340 II... Connector). 1 74 DSH 870.2800 II Recorder, Magnetic Tape, Medical. 1 74 DSI 870.1025 III Detector and Alarm...

21 CFR 898.13 - Compliance dates.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Frequency. 1 73 FLS 868.2375 II Monitor (Apnea Detector), Ventilatory Effort. 1 74 DPS 870.2340 II... Connector). 1 74 DSH 870.2800 II Recorder, Magnetic Tape, Medical. 1 74 DSI 870.1025 III Detector and Alarm...

21 CFR 898.13 - Compliance dates.

Code of Federal Regulations, 2014 CFR

2014-04-01

... Frequency. 1 73 FLS 868.2375 II Monitor (Apnea Detector), Ventilatory Effort. 1 74 DPS 870.2340 II... Connector). 1 74 DSH 870.2800 II Recorder, Magnetic Tape, Medical. 1 74 DSI 870.1025 III Detector and Alarm...

21 CFR 898.13 - Compliance dates.

Code of Federal Regulations, 2013 CFR

2013-04-01

... Frequency. 1 73 FLS 868.2375 II Monitor (Apnea Detector), Ventilatory Effort. 1 74 DPS 870.2340 II... Connector). 1 74 DSH 870.2800 II Recorder, Magnetic Tape, Medical. 1 74 DSI 870.1025 III Detector and Alarm...

21 CFR 898.13 - Compliance dates.

Code of Federal Regulations, 2012 CFR

2012-04-01

... Frequency. 1 73 FLS 868.2375 II Monitor (Apnea Detector), Ventilatory Effort. 1 74 DPS 870.2340 II... Connector). 1 74 DSH 870.2800 II Recorder, Magnetic Tape, Medical. 1 74 DSI 870.1025 III Detector and Alarm...

Peripheral muscle ergoreceptors and ventilatory response during exercise recovery in heart failure.

PubMed

Francis, N; Cohen-Solal, A; Logeart, D

1999-03-01

Recent studies have suggested that the increased ventilatory response during exercise in patients with chronic heart failure was related to the activation of muscle metaboreceptors. To address this issue, 23 patients with heart failure and 7 normal subjects performed arm and leg bicycle exercises with and without cuff inflation around the arms or the thighs during recovery. Obstruction slightly reduced ventilation and gas exchange variables at recovery but did not change the kinetics of recovery of these parameters compared with nonobstructed recovery: half-time of ventilation recovery was 175 +/- 54 to 176 +/- 40 s in patients and 155 +/- 66 to 127 +/- 13 s in controls (P < 0.05, patients vs. controls, not significant within each group from baseline to obstructed recovery). We conclude that muscle metaboreceptor activation does not seem to play a role in the exertion hyperventilation of patients with heart failure.

[Concepts and monitoring of pulmonary mechanic in patients under ventilatory support in intensive care unit].

PubMed

Faustino, Eduardo Antonio

2007-06-01

In mechanical ventilation, invasive and noninvasive, the knowledge of respiratory mechanic physiology is indispensable to take decisions and into the efficient management of modern ventilators. Monitoring of pulmonary mechanic parameters is been recommended from all the review works and clinical research. The objective of this study was review concepts of pulmonary mechanic and the methods used to obtain measures in the bed side, preparing a rational sequence to obtain this data. It was obtained bibliographic review through data bank LILACS, MedLine and PubMed, from the last ten years. This review approaches parameters of resistance, pulmonary compliance and intrinsic PEEP as primordial into comprehension of acute respiratory failure and mechanic ventilatory support, mainly in acute respiratory distress syndrome (ARDS) and in chronic obstructive pulmonary disease (COPD). Monitoring pulmonary mechanics in patients under mechanical ventilation in intensive care units gives relevant informations and should be implemented in a rational and systematic way.

Can high-intensity exercise be more pleasant?: attentional dissociation using music and video.

PubMed

Jones, Leighton; Karageorghis, Costas I; Ekkekakis, Panteleimon

2014-10-01

Theories suggest that external stimuli (e.g., auditory and visual) may be rendered ineffective in modulating attention when exercise intensity is high. We examined the effects of music and parkland video footage on psychological measures during and after stationary cycling at two intensities: 10% of maximal capacity below ventilatory threshold and 5% above. Participants (N = 34) were exposed to four conditions at each intensity: music only, video only, music and video, and control. Analyses revealed main effects of condition and exercise intensity for affective valence and perceived activation (p < .001), state attention (p < .05), and exercise enjoyment (p < .001). The music-only and music-and-video conditions led to the highest valence and enjoyment scores during and after exercise regardless of intensity. Findings indicate that attentional manipulations can exert a salient influence on affect and enjoyment even at intensities slightly above ventilatory threshold.

[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.

The effect of electromagnetic interference from mobile communication on the performance of intensive care ventilators.

PubMed

Jones, R P; Conway, D H

2005-08-01

Electromagnetic interference produced by wireless communication can affect medical devices and hospital policies exist to address this risk. During the transfer of ventilated patients, these policies may be compromised by essential communication between base and receiving hospitals. Local wireless networks (e.g. Bluetooth) may reduce the 'spaghetti syndrome' of wires and cables seen on intensive care units, but also generate electromagnetic interference. The aim of this study was to investigate these effects on displayed and actual ventilator performance. Five ventilators were tested: Drager Oxylog 2000, BREAS LTV-1000, Respironics BiPAP VISION, Puritan Bennett 7200 and 840. Electromagnetic interference was generated by three devices: Simoco 8020 radio handset, Nokia 7210 and Nokia 6230 mobile phone, Nokia 6230 communicating via Bluetooth with a Palm Tungsten T Personal Digital Assistant. We followed the American National Standard Recommended Practice for On-Site, Ad Hoc Testing (ANSI C63) for electromagnetic interference. We used a ventilator tester, to simulate healthy adult lungs and measure ventilator performance. The communication device under test was moved in towards each ventilator from a distance of 1 m in six axes. Alarms or error codes on the ventilator were recorded, as was ventilator performance. All ventilators tested, except for the Respironics VISION, showed a display error when subjected to electromagnetic interference from the Nokia phones and Simoco radio. Ventilator performance was only affected by the radio which caused the Puritan Bennett 840 to stop functioning completely. The transfer ventilators' performance were not affected by radio or mobile phone, although the mobile phone did trigger a low-power alarm. Effects on intensive care ventilators included display reset, with the ventilator restoring normal display function within 2 s, and low-power/low-pressure alarms. Bluetooth transmission had no effect on the function of all the ventilators tested. In a clinical setting, high-power-output devices such as a two-way radio may cause significant interference in ventilator function. Medium-power-output devices such as mobile phones may cause minor alarm triggers. Low-power-output devices such as Bluetooth appear to cause no interference with ventilator function.

PDGF-beta receptor expression and ventilatory acclimatization to hypoxia in the rat.

PubMed

Alea, O A; Czapla, M A; Lasky, J A; Simakajornboon, N; Gozal, E; Gozal, D

2000-11-01

Activation of platelet-derived growth factor-beta (PDGF-beta) receptors in the nucleus of the solitary tract (nTS) modulates the late phase of the acute hypoxic ventilatory response (HVR) in the rat. We hypothesized that temporal changes in PDGF-beta receptor expression could underlie the ventilatory acclimatization to hypoxia (VAH). Normoxic ventilation was examined in adult Sprague-Dawley rats chronically exposed to 10% O(2), and at 0, 1, 2, 7, and 14 days, Northern and Western blots of the dorsocaudal brain stem were performed for assessment of PDGF-beta receptor expression. Although no significant changes in PDGF-beta receptor mRNA occurred over time, marked attenuation of PDGF-beta receptor protein became apparent after day 7 of hypoxic exposure. Such changes were significantly correlated with concomitant increases in normoxic ventilation, i.e., with VAH (r: -0.56, P < 0.005). In addition, long-term administration of PDGF-BB in the nTS via osmotic pumps loaded with either PDGF-BB (n = 8) or vehicle (Veh; n = 8) showed that although no significant changes in the magnitude of acute HVR occurred in Veh over time, the typical attenuation of HVR by PDGF-BB decreased over time. Furthermore, PDGF-BB microinjections did not attenuate HVR in acclimatized rats at 7 and 14 days of hypoxia (n = 10). We conclude that decreased expression of PDGF-beta receptors in the dorsocaudal brain stem correlates with the magnitude of VAH. We speculate that the decreased expression of PDGF-beta receptors is mediated via internalization and degradation of the receptor rather than by transcriptional regulation.

Fluctuations of the fractal dimension of the electroencephalogram during periodic breathing in heart failure patients.

PubMed

Maestri, Roberto; La Rovere, Maria Teresa; Robbi, Elena; Pinna, Gian Domenico

2010-06-01

The physiological mechanisms responsible for periodic breathing (PB) in heart failure (HF) patients are still debated. A role for rhythmic shifts in the level of wakefulness has been suggested, but their existence has never been proven. In this study we investigated the existence of an oscillation in EEG activity during PB in these patients and assessed its relationship with the ventilatory oscillation. EEG activity was measured by the fractal dimension (FD) and by a spectral technique (weighted mean frequency, WMF) in 17 stable HF patients (mean age +/- SD: 57+/-10 yrs, NYHA class: 2.6 +/- 0.4, LVEF: 24 +/- 6%), with sustained PB during supine rest. The relationship between minute ventilation (MV) signal and FD and WMF was assessed by coherence analysis. Most patients (10/17) showed a well defined oscillation in FD and WMF at the frequency of PB closely linked (coherence > 0.7) with the oscillation of MV. In the remaining patients, neither FD nor WMF showed a clear oscillatory pattern synchronous with MV. Overall, the two EEG-derived parameters showed the same coherence with the ventilatory oscillation (mean coherence +/- SD: 0.65 +/- 0.25 vs 0.66 +/- 0.23, for FD and WMF respectively, p = 0.44). Our results provide evidence that during PB in HF patients, EEG activity often, but not always, fluctuates synchronously with the ventilatory oscillation. These fluctuations can be effectively detected by the fractal dimension, but classical spectral methods provide substantially the same information. Other mechanisms, particularly chemical instability in the respiratory control system, are likely to play a role in the genesis of PB.

Neonatal stress affects the aging trajectory of female rats on the endocrine, temperature, and ventilatory responses to hypoxia.

PubMed

Fournier, Sébastien; Gulemetova, Roumiana; Baldy, Cécile; Joseph, Vincent; Kinkead, Richard

2015-04-01

Human and animal studies on sleep-disordered breathing and respiratory regulation show that the effects of sex hormones are heterogeneous. Because neonatal stress results in sex-specific disruption of the respiratory control in adult rats, we postulate that it might affect respiratory control modulation induced by ovarian steroids in female rats. The hypoxic ventilatory response (HVR) of adult female rats exposed to neonatal maternal separation (NMS) is ∼30% smaller than controls (24), but consequences of NMS on respiratory control in aging female rats are unknown. To address this issue, whole body plethysmography was used to evaluate the impact of NMS on the HVR (12% O2, 20 min) of middle-aged (MA; ∼57 wk old) female rats. Pups subjected to NMS were placed in an incubator 3 h/day for 10 consecutive days (P3 to P12). Controls were undisturbed. To determine whether the effects were related to sexual hormone decline or aging per se, experiments were repeated on bilaterally ovariectomized (OVX) young (∼12 wk old) adult female rats. OVX and MA both reduced the HVR significantly in control rats but had little effect on the HVR of NMS females. OVX (but not aging) reduced the anapyrexic response in both control and NMS animals. These results show that hormonal decline decreases the HVR of control animals, while leaving that of NMS female animals unaffected. This suggests that neonatal stress alters the interaction between sex hormone regulation and the development of body temperature, hormonal, and ventilatory responses to hypoxia. Copyright © 2015 the American Physiological Society.

The vesicular glutamate transporter VGLUT3 contributes to protection against neonatal hypoxic stress

PubMed Central

Miot, Stéphanie; Voituron, Nicolas; Sterlin, Adélaïde; Vigneault, Erika; Morel, Lydie; Matrot, Boris; Ramanantsoa, Nelina; Amilhon, Bénédicte; Poirel, Odile; Lepicard, Ève; El Mestikawy, Salah; Hilaire, Gérard; Gallego, Jorge

2012-01-01

Neonates respond to hypoxia initially by increasing ventilation, and then by markedly decreasing both ventilation (hypoxic ventilatory decline) and oxygen consumption (hypoxic hypometabolism). This latter process, which vanishes with age, reflects a tight coupling between ventilatory and thermogenic responses to hypoxia. The neurological substrate of hypoxic hypometabolism is unclear, but it is known to be centrally mediated, with a strong involvement of the 5-hydroxytryptamine (5-HT, serotonin) system. To clarify this issue, we investigated the possible role of VGLUT3, the third subtype of vesicular glutamate transporter. VGLUT3 contributes to glutamate signalling by 5-HT neurons, facilitates 5-HT transmission and is expressed in strategic regions for respiratory and thermogenic control. We therefore assumed that VGLUT3 might significantly contribute to the response to hypoxia. To test this possibility, we analysed this response in newborn mice lacking VGLUT3 using anatomical, biochemical, electrophysiological and integrative physiology approaches. We found that the lack of VGLUT3 did not affect the histological organization of brainstem respiratory networks or respiratory activity under basal conditions. However, it impaired respiratory responses to 5-HT and anoxia, showing a marked alteration of central respiratory control. These impairments were associated with altered 5-HT turnover at the brainstem level. Furthermore, under cold conditions, the lack of VGLUT3 disrupted the metabolic rate, body temperature, baseline breathing and the ventilatory response to hypoxia. We conclude that VGLUT3 expression is dispensable under basal conditions but is required for optimal response to hypoxic stress in neonates. PMID:22890712

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

Energy expenditure and influence of physiologic factors during marathon running.

PubMed

Loftin, Mark; Sothern, Melinda; Koss, Cathie; Tuuri, Georgianna; Vanvrancken, Connie; Kontos, Anthony; Bonis, Marc

2007-11-01

This study examined energy expenditure and physiologic determinants for marathon performance in recreational runners. Twenty recreational marathon runners participated (10 males aged 41 +/- 11.3 years, 10 females aged 42.7 +/- 11.7 years). Each subject completed a V(.-)O2max and a 1-hour treadmill run at recent marathon pace, and body composition was indirectly determined via dual energy X-ray absorptiometry. The male runners exhibited higher V(.-)O2max (ml x kg(-1) x min(-1)) values (52.6 +/- 5.5) than their female counterparts (41.9 +/- 6.6), although ventilatory threshold (T-vent) values were similar between groups (males: 76.2 +/- 6.1 % of V(.-)O2max, females: 75.1 +/- 5.1%). The male runners expended more energy (2,792 +/- 235 kcal) for their most recent marathon as calculated from the 1-hour treadmill run at marathon pace than the female runners (2,436 +/- 297 kcal). Body composition parameters correlated moderately to highly (r ranging from 0.50 to 0.87) with marathon run time. Also, V(.-)O2max (r = -0.73) and ventilatory threshold (r = -0.73) moderately correlated with marathon run time. As a group, the participants ran near their ventilatory threshold for their most recent marathon (r = 0.74). These results indicate the influence of body size on marathon run performance. In general, the larger male and female runners ran slower and expended more kilocalories than smaller runners. Regardless of marathon finishing time, the runners maintained a pace near their T-vent, and as T-vent or V(.-)O2max increased, marathon performance time decreased.

Comparison of Ventilatory Measures and 20 km Time Trial Performance.

PubMed

Peveler, Willard W; Shew, Brandy; Johnson, Samantha; Sanders, Gabe; Kollock, Roger

2017-01-01

Performance threshold measures are used to predict cycling performance. Previous research has focused on long time trials (≥ 40 km) using power at ventilatory threshold and respiratory threshold to estimate time trial performance. As intensity greatly differs during shorter time trails applying findings from longer time trials may not be appropriate. The use of heart rate measures to determine 20 km time trial performance has yet to be examined. The purpose of this study was to determine the effectiveness of heart rate measures at ventilatory threshold (VE/VO 2 Plotted and VT determined by software) and respiratory threshold (RER of 0.95, 1.00, and 1.05) to predict 20 km time trial performance. Eighteen cyclists completed a VO 2max protocol and two 20 km time trials. Average heart rates from 20 km time trials were compared with heart rates from performance threshold measures (VT plotted, VT software, and an RER at 0.95, 1.00, and 1.05) using repeated measures ANOVA. Significance was set a priori at P ≤ 0.05. The only measure not found to be significantly different in relation to time trial performance was HR at an RER of 1.00 (166.61±12.70 bpm vs. 165.89 ± 9.56 bpm, p = .671). VT plotting and VT determined by software were found to underestimate time trial performance by 3% and 8% respectively. From these findings it is recommended to use heart rate at a RER of 1.00 in order to determine 20 km time trial intensity.

The obstructive sleep apnoea syndrome in adolescents.

PubMed

Marcus, Carole L; Keenan, Brendan T; Huang, Jingtao; Yuan, Haibo; Pinto, Swaroop; Bradford, Ruth M; Kim, Christopher; Bagchi, Sheila; Comyn, Francois-Louis; Wang, Stephen; Tapia, Ignacio E; Maislin, Greg; Cielo, Christopher M; Traylor, Joel; Torigian, Drew A; Schwab, Richard J

2017-08-01

The obstructive sleep apnoea syndrome (OSAS) results from a combination of structural and neuromotor factors; however, the relative contributions of these factors have not been studied during the important developmental phase of adolescence. We hypothesised that adenotonsillar volume (ATV), nasopharyngeal airway volume (NPAV), upper airway critical closing pressure (Pcrit) in the hypotonic and activated neuromotor states, upper airway electromyographic response to subatmospheric pressure and the ventilatory response to CO 2 during sleep would be major predictors of OSAS risk. 42 obese adolescents with OSAS and 37 weight-matched controls underwent upper airway MRI, measurements of Pcrit, genioglossal electromyography and ventilatory response to CO 2 during wakefulness and sleep. ATV, NPAV, activated and hypotonic Pcrit, genioglossal electromyography and ventilatory response to CO 2 during sleep were all associated with OSAS risk. Multivariate models adjusted for age, gender, body mass index and race indicated that ATV, NPAV and activated Pcrit each independently affected apnoea risk in adolescents; genioglossal electromyography was independently associated in a reduced sample. There was significant interaction between NPAV and activated Pcrit (p=0.021), with activated Pcrit more strongly associated with OSAS in adolescents with larger NPAVs and NPAV more strongly associated with OSAS in adolescents with more negative activated closing pressure. OSAS in adolescents is mediated by a combination of anatomic (ATV, NPAV) and neuromotor factors (activated Pcrit). This may have important implications for the management of OSAS in adolescents. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Dexamethasone mimics aspects of physiological acclimatization to 8 hours of hypoxia but suppresses plasma erythropoietin

PubMed Central

Liu, Chun; Croft, Quentin P. P.; Kalidhar, Swati; Brooks, Jerome T.; Herigstad, Mari; Smith, Thomas G.; Dorrington, Keith L.

2013-01-01

Dexamethasone ameliorates the severity of acute mountain sickness (AMS) but it is unknown whether it obtunds normal physiological responses to hypoxia. We studied whether dexamethasone enhanced or inhibited the ventilatory, cardiovascular, and pulmonary vascular responses to sustained (8 h) hypoxia. Eight healthy volunteers were studied, each on four separate occasions, permitting four different protocols. These were: dexamethasone (20 mg orally) beginning 2 h before a control period of 8 h of air breathing; dexamethasone with 8 h of isocapnic hypoxia (end-tidal Po2 = 50 Torr); placebo with 8 h of air breathing; and placebo with 8 h of isocapnic hypoxia. Before and after each protocol, the following were determined under both euoxic and hypoxic conditions: ventilation; pulmonary artery pressure (estimated using echocardiography to assess maximum tricuspid pressure difference); heart rate; and cardiac output. Plasma concentrations of erythropoietin (EPO) were also determined. Dexamethasone had no early (2-h) effect on any variable. Both dexamethasone and 8 h of hypoxia increased euoxic values of ventilation, pulmonary artery pressure, and heart rate, together with the ventilatory sensitivity to acute hypoxia. These effects were independent and additive. Eight hours of hypoxia, but not dexamethasone, increased the sensitivity of pulmonary artery pressure to acute hypoxia. Dexamethasone, but not 8 h of hypoxia, increased both cardiac output and systemic arterial pressure. Dexamethasone abolished the rise in EPO induced by 8 h of hypoxia. In summary, dexamethasone enhances ventilatory acclimatization to hypoxia. Thus, dexamethasone in AMS may improve oxygenation and thereby indirectly lower pulmonary artery pressure. PMID:23393065

Respiratory, allergy and eye problems in bagasse-exposed sugar cane workers in Costa Rica.

PubMed

Gascon, Mireia; Kromhout, Hans; Heederik, Dick; Eduard, Wijnand; van Wendel de Joode, Berna

2012-05-01

To evaluate bagasse (sugar cane fibres) and microbiological exposure among sugar cane refinery workers in Costa Rica and its relationships with respiratory, allergy and eye problems. Ventilatory lung function and total serum IgE were measured in 104 sugar cane workers in five departments at one refinery before the harvesting season, and repeated for 77 of the workers at the end of the season. Information on the prevalence of respiratory and other symptoms was collected with a standardised questionnaire. During the harvesting season, inhalable dust, endotoxin and mould levels were measured among 74 randomly selected sugar cane workers across departments. During the harvesting season, dust levels were relatively high in some departments, while endotoxin and mould levels were around background levels. Workers' ventilatory lung function differed between departments before, but not during the harvesting season or between seasons. During the harvesting season, the prevalence of wheeze and eye problems almost doubled in workers exposed to bagasse and other types of dust, whereas shortness of breath and rhinitis increased only in bagasse-exposed workers. Reporting wheeze and shortness of breath was positively associated with the number of years working at the refinery, suggesting a long-term health effect. In this refinery, the differences in workers' ventilatory lung function before the harvesting season are unlikely to be explained by bagasse exposure. However, the increase in reported symptoms (wheeze, shortness of breath, eye problems and rhinitis) over the season is likely due to irritation by dust, in particular bagasse, rather than microbiological agents.

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.

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.

Postural control and ventilatory drive during voluntary hyperventilation and carbon dioxide rebreathing.

PubMed

David, Pascal; Laval, David; Terrien, Jérémy; Petitjean, Michel

2012-01-01

The present study sought to establish links between hyperventilation and postural stability. Eight university students were asked to stand upright under two hyperventilation conditions applied randomly: (1) a metabolic hyperventilation induced by 5 min of hypercapnic-hyperoxic rebreathing (CO(2)-R); and, (2) a voluntary hyperventilation (VH) of 3 min imposed by a metronome set at 25 cycles per min. Recordings were obtained with eyes open, with the subjects standing on a force plate over 20-s periods. Ventilatory response, displacements in the centre of pressure in both the frontal and sagittal planes and fluctuations in the three planes of the ground reaction force were monitored in the time and frequency domains. Postural changes related to respiratory variations were quantified by coherence analysis. Myoelectric activities of the calf muscles were recorded using surface electromyography. Force plate measurements revealed a reduction in postural stability during both CO(2)-R and VH conditions, mainly in the sagittal plane. Coherence analysis provided evidence of a ventilatory origin in the vertical ground reaction force fluctuations during VH. Electromyographic analyses showed different leg muscles strategies, assuming the existence of links between the control of respiration and the control of posture. Our results suggest that the greater disturbing effects caused by voluntary hyperventilation on body balance are more compensated when respiration is under automatic control. These findings may have implications for understanding the organisation of postural and respiratory activities and suggest that stability of the body may be compromised in situations in which respiratory demand increases and requires voluntary control.

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.

Intricate but tight coupling of spiracular activity and abdominal ventilation during locust discontinuous gas exchange cycles.

PubMed

Talal, Stav; Gefen, Eran; Ayali, Amir

2018-03-15

Discontinuous gas exchange (DGE) is the best studied among insect gas exchange patterns. DGE cycles comprise three phases, which are defined by their spiracular state: closed, flutter and open. However, spiracle status has rarely been monitored directly; rather, it is often assumed based on CO 2 emission traces. In this study, we directly recorded electromyogram (EMG) signals from the closer muscle of the second thoracic spiracle and from abdominal ventilation muscles in a fully intact locust during DGE. Muscular activity was monitored simultaneously with CO 2 emission, under normoxia and under various experimental oxic conditions. Our findings indicate that locust DGE does not correspond well with the commonly described three-phase cycle. We describe unique DGE-related ventilation motor patterns, coupled to spiracular activity. During the open phase, when CO 2 emission rate is highest, the thoracic spiracles do not remain open; rather, they open and close rapidly. This fast spiracle activity coincides with in-phase abdominal ventilation, while alternating with the abdominal spiracle and thus facilitating a unidirectional air flow along the main trachea. A change in the frequency of rhythmic ventilation during the open phase suggests modulation by intra-tracheal CO 2 levels. A second, slow ventilatory movement pattern probably serves to facilitate gas diffusion during spiracle closure. Two flutter-like patterns are described in association with the different types of ventilatory activity. We offer a modified mechanistic model for DGE in actively ventilating insects, incorporating ventilatory behavior and changes in spiracle state. © 2018. Published by The Company of Biologists Ltd.

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.

Phrenic Motor Unit Recruitment during Ventilatory and Non-Ventilatory Behaviors

PubMed Central

Mantilla, Carlos B.; Sieck, Gary C.

2011-01-01

Phrenic motoneurons are located in the cervical spinal cord and innervate the diaphragm muscle, the main inspiratory muscle in mammals. Similar to other skeletal muscles, phrenic motoneurons and diaphragm muscle fibers form motor units which are the final element of neuromotor control. In addition to their role in sustaining ventilation, phrenic motor units are active in other non-ventilatory behaviors important for airway clearance such as coughing or sneezing. Diaphragm muscle fibers comprise all fiber types and are commonly classified based on expression of contractile proteins including myosin heavy chain isoforms. Although there are differences in contractile and fatigue properties across motor units, there is a matching of properties for the motor neuron and muscle fibers within a motor unit. Motor units are generally recruited in order such that fatigue-resistant motor units are recruited earlier and more often than more fatigable motor units. Thus, in sustaining ventilation, fatigue-resistant motor units are likely required. Based on a series of studies in cats, hamsters and rats, an orderly model of motor unit recruitment was proposed that takes into consideration the maximum forces generated by single type-identified diaphragm muscle fibers as well as the proportion of the different motor unit types. Using this model, eupnea can be accomplished by activation of only slow-twitch diaphragm motor units and only a subset of fast-twitch, fatigue-resistant units. Activation of fast-twitch fatigable motor units only becomes necessary when accomplishing tasks that require greater force generation by the diaphragm muscle, e.g., sneezing and coughing. PMID:21763470

Phrenic motor unit recruitment during ventilatory and non-ventilatory behaviors.

PubMed

Mantilla, Carlos B; Sieck, Gary C

2011-10-15

Phrenic motoneurons are located in the cervical spinal cord and innervate the diaphragm muscle, the main inspiratory muscle in mammals. Similar to other skeletal muscles, phrenic motoneurons and diaphragm muscle fibers form motor units which are the final element of neuromotor control. In addition to their role in sustaining ventilation, phrenic motor units are active in other non-ventilatory behaviors important for airway clearance such as coughing or sneezing. Diaphragm muscle fibers comprise all fiber types and are commonly classified based on expression of contractile proteins including myosin heavy chain isoforms. Although there are differences in contractile and fatigue properties across motor units, there is a matching of properties for the motor neuron and muscle fibers within a motor unit. Motor units are generally recruited in order such that fatigue-resistant motor units are recruited earlier and more often than more fatigable motor units. Thus, in sustaining ventilation, fatigue-resistant motor units are likely required. Based on a series of studies in cats, hamsters and rats, an orderly model of motor unit recruitment was proposed that takes into consideration the maximum forces generated by single type-identified diaphragm muscle fibers as well as the proportion of the different motor unit types. Using this model, eupnea can be accomplished by activation of only slow-twitch diaphragm motor units and only a subset of fast-twitch, fatigue-resistant units. Activation of fast-twitch fatigable motor units only becomes necessary when accomplishing tasks that require greater force generation by the diaphragm muscle, e.g., sneezing and coughing. Copyright © 2011 Elsevier B.V. All rights reserved.

Dynamic Characteristics of Ventilatory and Gas Exchange during Sinusoidal Walking in Humans.

PubMed

Fukuoka, Yoshiyuki; Iihoshi, Masaaki; Nazunin, Juhelee Tuba; Abe, Daijiro; Fukuba, Yoshiyuki

2017-01-01

Our present study investigated whether the ventilatory and gas exchange responses show different dynamics in response to sinusoidal change in cycle work rate or walking speed even if the metabolic demand was equivalent in both types of exercise. Locomotive parameters (stride length and step frequency), breath-by-breath ventilation (V̇E) and gas exchange (CO2 output (V̇CO2) and O2 uptake (V̇O2)) responses were measured in 10 healthy young participants. The speed of the treadmill was sinusoidally changed between 3 km·h-1 and 6 km·h-1 with various periods (from 10 to 1 min). The amplitude of locomotive parameters against sinusoidal variation showed a constant gain with a small phase shift, being independent of the oscillation periods. In marked contrast, when the periods of the speed oscillations were shortened, the amplitude of V̇E decreased sharply whereas the phase shift of V̇E increased. In comparing walking and cycling at the equivalent metabolic demand, the amplitude of V̇E during sinusoidal walking (SW) was significantly greater than that during sinusoidal cycling (SC), and the phase shift became smaller. The steeper slope of linear regression for the V̇E amplitude ratio to V̇CO2 amplitude ratio was observed during SW than SC. These findings suggested that the greater amplitude and smaller phase shift of ventilatory dynamics were not equivalent between SW and SC even if the metabolic demand was equivalent between both exercises. Such phenomenon would be derived from central command in proportion to locomotor muscle recruitment (feedforward) and muscle afferent feedback.

Physiological impact of patent foramen ovale on pulmonary gas exchange, ventilatory acclimatization, and thermoregulation.

PubMed

Lovering, Andrew T; Elliott, Jonathan E; Davis, James T

2016-08-01

The foramen ovale, which is part of the normal fetal cardiopulmonary circulation, fails to close after birth in ∼35% of the population and represents a potential source of right-to-left shunt. Despite the prevalence of patent foramen ovale (PFO) in the general population, cardiopulmonary, exercise, thermoregulatory, and altitude physiologists may have underestimated the potential effect of this shunted blood flow on normal physiological processes in otherwise healthy humans. Because this shunted blood bypasses the respiratory system, it would not participate in either gas exchange or respiratory system cooling and may have impacts on other physiological processes that remain undetermined. The consequences of this shunted blood flow in PFO-positive (PFO+) subjects can potentially have a significant, and negative, impact on the alveolar-to-arterial oxygen difference (AaDO2), ventilatory acclimatization to high altitude and respiratory system cooling with PFO+ subjects having a wider AaDO2 at rest, during exercise after acclimatization, blunted ventilatory acclimatization, and a higher core body temperature (∼0.4(°)C) at rest and during exercise. There is also an association of PFO with high-altitude pulmonary edema and acute mountain sickness. These effects on physiological processes are likely dependent on both the presence and size of the PFO, with small PFOs not likely to have significant/measureable effects. The PFO can be an important determinant of normal physiological processes and should be considered a potential confounder to the interpretation of former and future data, particularly in small data sets where a significant number of PFO+ subjects could be present and significantly impact the measured outcomes.

Quantifying the Arousal Threshold Using Polysomnography in Obstructive Sleep Apnea.

PubMed

Sands, Scott A; Terrill, Philip I; Edwards, Bradley A; Taranto Montemurro, Luigi; Azarbarzin, Ali; Marques, Melania; de Melo, Camila M; Loring, Stephen H; Butler, James P; White, David P; Wellman, Andrew

2018-01-01

Precision medicine for obstructive sleep apnea (OSA) requires noninvasive estimates of each patient's pathophysiological "traits." Here, we provide the first automated technique to quantify the respiratory arousal threshold-defined as the level of ventilatory drive triggering arousal from sleep-using diagnostic polysomnographic signals in patients with OSA. Ventilatory drive preceding clinically scored arousals was estimated from polysomnographic studies by fitting a respiratory control model (Terrill et al.) to the pattern of ventilation during spontaneous respiratory events. Conceptually, the magnitude of the airflow signal immediately after arousal onset reveals information on the underlying ventilatory drive that triggered the arousal. Polysomnographic arousal threshold measures were compared with gold standard values taken from esophageal pressure and intraoesophageal diaphragm electromyography recorded simultaneously (N = 29). Comparisons were also made to arousal threshold measures using continuous positive airway pressure (CPAP) dial-downs (N = 28). The validity of using (linearized) nasal pressure rather than pneumotachograph ventilation was also assessed (N = 11). Polysomnographic arousal threshold values were correlated with those measured using esophageal pressure and diaphragm EMG (R = 0.79, p < .0001; R = 0.73, p = .0001), as well as CPAP manipulation (R = 0.73, p < .0001). Arousal threshold estimates were similar using nasal pressure and pneumotachograph ventilation (R = 0.96, p < .0001). The arousal threshold in patients with OSA can be estimated using polysomnographic signals and may enable more personalized therapeutic interventions for patients with a low arousal threshold. © Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

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...

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.

Ventilation rates and activity levels of juvenile jumbo squid under metabolic suppression in the oxygen minimum zone.

PubMed

Trübenbach, Katja; Pegado, Maria R; Seibel, Brad A; Rosa, Rui

2013-02-01

The Humboldt (jumbo) squid, Dosidicus gigas, is a part-time resident of the permanent oxygen minimum zone (OMZ) in the Eastern Tropical Pacific and, thereby, it encounters oxygen levels below its critical oxygen partial pressure. To better understand the ventilatory mechanisms that accompany the process of metabolic suppression in these top oceanic predators, we exposed juvenile D. gigas to the oxygen levels found in the OMZ (1% O(2), 1 kPa, 10 °C) and measured metabolic rate, activity cycling patterns, swimming mode, escape jet (burst) frequency, mantle contraction frequency and strength, stroke volume and oxygen extraction efficiency. In normoxia, metabolic rate varied between 14 and 29 μmol O(2) g(-1) wet mass h(-1), depending on the level of activity. The mantle contraction frequency and strength were linearly correlated and increased significantly with activity level. Additionally, an increase in stroke volume and ventilatory volume per minute was observed, followed by a mantle hyperinflation process during high activity periods. Squid metabolic rate dropped more than 75% during exposure to hypoxia. Maximum metabolic rate was not achieved under such conditions and the metabolic scope was significantly decreased. Hypoxia changed the relationship between mantle contraction strength and frequency from linear to polynomial with increasing activity, indicating that, under hypoxic conditions, the jumbo squid primarily increases the strength of mantle contraction and does not regulate its frequency. Under hypoxia, jumbo squid also showed a larger inflation period (reduced contraction frequency) and decreased relaxed mantle diameter (shortened diffusion pathway), which optimize oxygen extraction efficiency (up to 82%/34%, without/with consideration of 60% potential skin respiration). Additionally, they breathe 'deeply', with more powerful contractions and enhanced stroke volume. This deep-breathing behavior allows them to display a stable ventilatory volume per minute, and explains the maintenance of the squid's cycling activity under such O(2) conditions. During hypoxia, the respiratory cycles were shorter in length but increased in frequency. This was accompanied by an increase in the number of escape jets during active periods and a faster switch between swimming modes. In late hypoxia (onset ~170 ± 10 min), all the ventilatory processes were significantly reduced and followed by a lethargic state, a behavior that seems closely associated with the process of metabolic suppression and enables the squid to extend its residence time in the OMZ.

Development of an anaesthetized-rat model of exercise hyperpnoea: an integrative model of respiratory control using an equilibrium diagram.

PubMed

Miyamoto, Tadayoshi; Manabe, Kou; Ueda, Shinya; Nakahara, Hidehiro

2018-05-01

What is the central question of this study? The lack of useful small-animal models for studying exercise hyperpnoea makes it difficult to investigate the underlying mechanisms of exercise-induced ventilatory abnormalities in various disease states. What is the main finding and its importance? We developed an anaesthetized-rat model for studying exercise hyperpnoea, using a respiratory equilibrium diagram for quantitative characterization of the respiratory chemoreflex feedback system. This experimental model will provide an opportunity to clarify the major determinant mechanisms of exercise hyperpnoea, and will be useful for understanding the mechanisms responsible for abnormal ventilatory responses to exercise in disease models. Exercise-induced ventilatory abnormalities in various disease states seem to arise from pathological changes of respiratory regulation. Although experimental studies in small animals are essential to investigate the pathophysiological basis of various disease models, the lack of an integrated framework for quantitatively characterizing respiratory regulation during exercise prevents us from resolving these problems. The purpose of this study was to develop an anaesthetized-rat model for studying exercise hyperpnoea for quantitative characterization of the respiratory chemoreflex feedback system. In 24 anaesthetized rats, we induced muscle contraction by stimulating bilateral distal sciatic nerves at low and high voltage to mimic exercise. We recorded breath-by-breath respiratory gas analysis data and cardiorespiratory responses while running two protocols to characterize the controller and plant of the respiratory chemoreflex. The controller was characterized by determining the linear relationship between end-tidal CO 2 pressure (P ETC O2) and minute ventilation (V̇E), and the plant by the hyperbolic relationship between V̇E and P ETC O2. During exercise, the controller curve shifted upward without change in controller gain, accompanying increased oxygen uptake. The hyperbolic plant curve shifted rightward and downward depending on exercise intensity as predicted by increased metabolism. Exercise intensity-dependent changes in operating points (V̇E and P ETC O2) were estimated by integrating the controller and plant curves in a respiratory equilibrium diagram. In conclusion, we developed an anaesthetized-rat model for studying exercise hyperpnoea, using systems analysis for quantitative characterization of the respiratory system. This novel experimental model will be useful for understanding the mechanisms responsible for abnormal ventilatory responses to exercise in disease models. © 2018 Morinomiya University of Medical Sciences. Experimental Physiology © 2018 The Physiological Society.

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.

EMISSION PARTICLE-INDUCED VENTILATORY ABNORMALITIES IN A RAT MODEL OF PULMONARY HYPERTENSION

EPA Science Inventory

Abstract

Preexistent cardiopulmonary disease in humans appears to enhance susceptibility to the adverse effects of ambient particulate matter. Previous studies in this laboratory have demonstrated enhanced inflammation and mortality after intratracheal instillation...

Whole Body Plethysmography Reveals Differential Ventilatory Responses to Ozone in Rat Models of Cardiovascular Disease

EPA Science Inventory

Increasingly, urban air pollution is recognized as an important determinant of cardiovascular disease. Host susceptibility to air pollution can vary due to genetic predisposition and underlying disease. To elucidate key factors of host ...

Respiratory comfort and breathing pattern during volume proportional assist ventilation and pressure support ventilation: a study on volunteers with artificially reduced compliance.

PubMed

Mols, G; von Ungern-Sternberg, B; Rohr, E; Haberthür, C; Geiger, K; Guttmann, J

2000-06-01

To assess respiratory comfort and associated breathing pattern during volume assist (VA) as a component of proportional assist ventilation and during pressure support ventilation (PSV). Prospective, double-blind, interventional study. Laboratory. A total of 15 healthy volunteers (11 females, 4 males) aged 21-31 yrs. Decreased respiratory system compliance was simulated by banding of the thorax and abdomen. Volunteers breathed via a mouthpiece with VA and PSV each applied at two levels (VA, 8 cm H2O/L and 12 cm H2O/L; PSV, 10 cm H2O and 15 cm H2O) using a positive end-expiratory pressure of 5 cm H2O throughout. The study was subdivided into two parts. In Part 1, volunteers breathed three times with each of the four settings for 2 mins in random order. In Part 2, the first breath effects of multiple, randomly applied mode, and level shifts were studied. In Part 1, the volunteers were asked to estimate respiratory comfort in comparison with normal breathing using a visual analog scale. In Part 2, they were asked to estimate the change of respiratory comfort as increased, decreased, or unchanged immediately after a mode shift. Concomitantly, the respiratory pattern (change) was characterized with continuously measured tidal volume, respiratory rate, pressure, and gas flow. Respiratory comfort during VA was higher than during PSV. The higher support level was less important during VA but had a major negative influence on comfort during PSV. Both modes differed with respect to the associated breathing pattern. Variability of breathing was higher during VA than during PSV (Part 1). Changes in respiratory variables were associated with changes in respiratory comfort (Part 2). For volunteers breathing with artificially reduced respiratory system compliance, respiratory comfort is higher with VA than with PSV. This is probably caused by a better adaptation of the ventilatory support to the volunteer's need with VA.

Tele-monitoring of ventilator-dependent patients: a European Respiratory Society Statement.

PubMed

Ambrosino, Nicolino; Vitacca, Michele; Dreher, Michael; Isetta, Valentina; Montserrat, Josep M; Tonia, Thomy; Turchetti, Giuseppe; Winck, Joao Carlos; Burgos, Felip; Kampelmacher, Michael; Vagheggini, Guido

2016-09-01

The estimated prevalence of ventilator-dependent individuals in Europe is 6.6 per 100 000 people. The increasing number and costs of these complex patients make present health organisations largely insufficient to face their needs. As a consequence, their burden lays mostly over families. The need to reduce healthcare costs and to increase safety has prompted the development of tele-monitoring for home ventilatory assistance.A European Respiratory Society Task Force produced a literature research based statement on commonly accepted clinical criteria for indications, follow-up, equipment, facilities, legal and economic issues of tele-monitoring of these patients.Many remote health monitoring systems are available, ensuring safety, feasibility, effectiveness, sustainability and flexibility to face different patients' needs. The legal problems associated with tele-monitoring are still controversial. National and European Union (EU) governments should develop guidelines and ethical, legal, regulatory, technical, administrative standards for remote medicine. The economic advantages, if any, of this new approach must be compared to a "gold standard" of home care that is very variable among different European countries and within each European country.Much more research is needed before considering tele-monitoring a real improvement in the management of these patients. Copyright ©ERS 2016.

Fat embolism syndrome

PubMed Central

Richards, Robin R.

1997-01-01

Fat embolism syndrome, an important contributor to the development of acute respiratory distress syndrome, has been associated with both traumatic and nontraumatic disorders. Fat embolization after long bone trauma is probably common as a subclinical event. Fat emboli can deform and pass through the lungs, resulting in systemic embolization, most commonly to the brain and kidneys. The diagnosis of fat embolism syndrome is based on the patient’s history, supported by clinical signs of pulmonary, cerebral and cutaneous dysfunction and confirmed by the demonstration of arterial hypoxemia in the absence of other disorders. Treatment of fat embolism syndrome consists of general supportive measures, including splinting, maintenance of fluid and electrolyte balance and the administration of oxygen. Endotracheal intubation and mechanical ventilatory assistance can be indicated. The role of corticosteroids remains controversial. Early stabilization of long bone fractures has been shown to decrease the incidence of pulmonary complications. Clinical and experimental studies suggest that the exact method of fracture fixation plays a minor role in the development of pulmonary dysfunction. As more is learned about the specifics of the various triggers for the development of fat embolism syndrome, it is hoped that the prospect of more specific therapy for the prevention and treatment of this disorder will become a reality. PMID:9336522

Effects of exercise training on HbA1c and VO2peak in patients with type 2 diabetes and coronary artery disease: A randomised clinical trial.

PubMed

Byrkjeland, Rune; Njerve, Ida U; Anderssen, Sigmund; Arnesen, Harald; Seljeflot, Ingebjørg; Solheim, Svein

2015-09-01

Few exercise trials have focused on patients with both type 2 diabetes and coronary artery disease. We investigated the effects of 1 year of exercise training on HbA1c and VO(2peak) in these patients. Patients with type 2 diabetes and coronary artery disease (n = 137) were randomised to combined exercise training or control group. HbA(1c) was measured at the beginning and end of the study. Changes in VO(2peak), and also ventilatory threshold and time to exhaustion, were assessed by cardiopulmonary exercise testing. No differences in changes between the randomised groups were observed in HbA1c and VO(2peak), whereas ventilatory threshold and time to exhaustion increased significantly in the exercise group compared with the controls (p = 0.046 and p = 0.034). In patients without previous acute myocardial infarction and diabetes microvascular complications (n = 46), the exercise group did improve HbA1c and VO(2peak) compared with the controls (p = 0.052 and p = 0.035). No significant effects of exercise training on HbA(1c) or VO(2peak) were observed in patients with type 2 diabetes and coronary artery disease, although improvements were seen in patients without vascular complications beyond coronary artery disease, implying that the degree of vascular disease may influence exercise responses. Ventilatory threshold and time to exhaustion did increase significantly, indicating improved exercise performance despite the minor change in VO(2peak). © The Author(s) 2015.

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.

[Face protective patches do not reduce facial pressure ulcers in a simulated model of non-invasive ventilation].

PubMed

Riquelme M, Hugo; Wood V, David; Martínez F, Santiago; Carmona M, Fernando; Peña V, Axel; Wegner A, Adriana

2017-06-01

Noninvasive ventilation (NIV) frequently involves the development of facial pressure ulcers (FPU). Its prevention considers the empirical use of protective patches between skin and mask, in order to reduce the pressure exerted by it. To evaluate the effect of protective patches on the pressure exerted by the facial mask, and its impact on the programmed ventilatory parameters. Bilevel NIV simulated model using full face mask in phantom with a physiological airway (ALS PRO +) in supine position. Forehead, chin and cheekbones pressure were measured using 3 types of standard protective patches versus a control group using pressure sensors (Interlinks Electronics®). The values obtained with the protective patches-mask model were evaluated in the programmed variables maximum inspiratory flow (MIF)), expired tidal volume (Vte) and positive inspiratory pressure (IPAP), with Trilogy 100 ventilator, Respironics®. The programming and recording of the variables was carried out in 8 opportunities in each group by independent operators. There was no decrease in facial pressure with any of the protective patches compared to the control group. Moltopren increased facial pressure at all support points (p < 0.001), increased leakage, it decreased MIF, Vte and IPAP (p < 0.001). Hydrocolloid patches increased facial pressure only in the left cheekbone, increased leakage and decreased MIF. Polyurethane patches did not produce changes in facial pressure or ventilatory variables. The use of protective patches of moltopren, hydrocolloid and polyurethane transparent did not contribute to the decrease of the facial pressure. A deleterious effect of the moltopren and hydrocolloid patches was observed on the administration of ventilatory variables, concluding that the non-use of the protective patches allowed a better administration of the programmed parameters.

The prefrontal oxygenation and ventilatory responses at start of one-legged cycling exercise have relation to central command.

PubMed

Asahara, Ryota; Matsukawa, Kanji; Ishii, Kei; Liang, Nan; Endo, Kana

2016-11-01

When performing exercise arbitrarily, activation of central command should start before the onset of exercise, but when exercise is forced to start with cue, activation of central command should be delayed. We examined whether the in-advance activation of central command influenced the ventilatory response and reflected in the prefrontal oxygenation, by comparing the responses during exercise with arbitrary and cued start. The breath-by-breath respiratory variables and the prefrontal oxygenated-hemoglobin concentration (Oxy-Hb) were measured during one-legged cycling. Minute ventilation (V̇e) at the onset of arbitrary one-legged cycling was augmented to a greater extent than cued cycling, while end-tidal carbon dioxide tension (ETco 2 ) decreased irrespective of arbitrary or cued start. Symmetric increase in the bilateral prefrontal Oxy-Hb occurred before and at the onset of arbitrary one-legged cycling, whereas such an increase was absent with cued start. The time course and magnitude of the increased prefrontal oxygenation were not influenced by the extent of subjective rating of perceived exertion and were the same as those of the prefrontal oxygenation during two-legged cycling previously reported. Mental imagery or passive performance of the one-legged cycling increased V̇e and decreased ETco 2 Neither intervention, however, augmented the prefrontal Oxy-Hb. The changes in ETco 2 could not explain the prefrontal oxygenation response during voluntary or passive one-legged cycling. Taken together, it is likely that the in-advance activation of central command influenced the ventilatory response by enhancing minute ventilation at the onset of one-legged cycling exercise and reflected in the preexercise increase in the prefrontal oxygenation. Copyright © 2016 the American Physiological Society.

Relationship between arterial oxygen desaturation and ventilation during maximal exercise.

PubMed

Miyachi, M; Tabata, I

1992-12-01

The purpose of the present study was to investigate the contribution of ventilation to arterial O2 desaturation during maximal exercise. Nine untrained subjects and 22 trained long-distance runners [age 18-36 yr, maximal O2 uptake (VO2max) 48-74 ml.min-1 x kg-1] volunteered to participate in the study. The subjects performed an incremental exhaustive cycle ergometry test at 70 rpm of pedaling frequency, during which arterial O2 saturation (SaO2) and ventilatory data were collected every minute. SaO2 was estimated with a pulse oximeter. A significant positive correlation was found between SaO2 and end-tidal PO2 (PETO2; r = 0.72, r2 = 0.52, P < 0.001) during maximal exercise. These statistical results suggest that approximately 50% of the variability of SaO2 can be accounted for by differences in PETO2, which reflects alveolar PO2. Furthermore, PETO2 was highly correlated with the ventilatory equivalent for O2 (VE/VO2; r = 0.91, P < 0.001), which indicates that PETO2 could be the result of ventilation stimulated by maximal exercise. Finally, SaO2 was positively related to VE/VO2 during maximal exercise (r = 0.74, r2 = 0.55, P < 0.001). Therefore, one-half of the arterial O2 desaturation occurring during maximal exercise may be explained by less hyperventilation, specifically for our subjects, who demonstrated a wide range of trained states. Furthermore, we found an indirect positive correlation between SaO2 and ventilatory response to CO2 at rest (r = 0.45, P < 0.05), which was mediated by ventilation during maximal exercise. These data also suggest that ventilation is an important factor for arterial O2 desaturation during maximal exercise.

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

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

Lower hypoxic ventilatory response in smokers compared to non-smokers during abstinence from cigarettes.

PubMed

Hildebrandt, Wulf; Sauer, Roland; Koehler, Ulrich; Bärtsch, Peter; Kinscherf, Ralf

2016-11-24

Carotid body O 2 -chemosensitivity determines the hypoxic ventilatory response (HVR) as part of crucial regulatory reflex within oxygen homeostasis. Nicotine has been suggested to attenuate HVR in neonates of smoking mothers. However, whether smoking affects HVR in adulthood has remained unclear and probably blurred by acute ventilatory stimulation through cigarette smoke. We hypothesized that HVR is substantially reduced in smokers when studied after an overnight abstinence from cigarettes i.e. after nicotine elimination. We therefore determined the isocapnic HVR of 23 healthy male smokers (age 33.9 ± 2.0 years, BMI 24.2 ± 0.5 kg m -2 , mean ± SEM) with a smoking history of >8 years after 12 h of abstinence and compared it to that of 23 healthy male non-smokers matched for age and BMI. Smokers and non-smokers were comparable with regard to factors known to affect isocapnic HVR such as plasma levels of glucose and thiols as well as intracellular levels of glutathione in blood mononuclear cells. As a new finding, abstinent smokers had a significantly lower isocapnic HVR (0.024 ± 0.002 vs. 0.037 ± 0.003 l min -1 % -1 BMI -1 , P = 0.002) compared to non-smokers. However, upon re-exposure to cigarettes the smokers' HVR increased immediately to the non-smokers' level. This is the first report of a substantial HVR reduction in abstinent adult smokers which appears to be masked by daily smoking routine and may therefore have been previously overlooked. A low HVR may be suggested as a novel link between smoking and aggravated hypoxemia during sleep especially in relevant clinical conditions such as COPD.

Randomized Comparative Study of Intravenous Infusion of Three Different Fixed Doses of Milrinone in Pediatric Patients with Pulmonary Hypertension Undergoing Open Heart Surgery

PubMed Central

Barnwal, Neeraj Kumar; Umbarkar, Sanjeeta Rajendra; Sarkar, Manjula Sudeep; Dias, Raylene J

2017-01-01

Background: Pulmonary hypertension secondary to congenital heart disease is a common problem in pediatric patients presenting for open heart surgery. Milrinone has been shown to reduce pulmonary vascular resistance and pulmonary artery pressure in pediatric patients and neonates postcardiac surgery. We aimed to evaluate the postoperative outcome in such patients with three different fixed maintenance doses of milrinone. Methodology: Patients were randomized into three groups. All patients received fixed bolus dose of milrinone 50 μg/kg on pump during rewarming. Following this, patients in low-dose group received infusion of milrinone at the rate of 0.375 μg/kg/min, medium-dose group received 0.5 μg/kg/min, and high-dose group received 0.75 μg/kg/min over 24 h. Heart rate, mean arterial pressure (MAP), mean airway pressure (MaP), oxygenation index (OI), and central venous pressure (CVP) were compared at baseline and 24 h postoperatively. Dose of inotropic requirement, duration of ventilatory support and Intensive Care Unit (ICU) stay were noted. Results: MAP, MaP, OI, and CVP were comparable in all three groups postoperatively. All patients in the low-dose group required low inotropic support while 70% of patients in the high-dose group needed high inotropic support to manage episodes of hypotension (P = 0.000). Duration of ventilatory support and ICU stay in all three groups was comparable (P = 0.412, P = 0.165). Conclusion: Low-dose infusions while having a clinical impact were more beneficial in avoiding adverse events and decreasing inotropic requirement without affecting duration of ventilatory support and duration of ICU stay. PMID:28701597

Randomized comparative study of intravenous infusion of three different fixed doses of milrinone in pediatric patients with pulmonary hypertension undergoing open heart surgery.

PubMed

Barnwal, Neeraj Kumar; Umbarkar, Sanjeeta Rajendra; Sarkar, Manjula Sudeep; Dias, Raylene J

2017-01-01

Pulmonary hypertension secondary to congenital heart disease is a common problem in pediatric patients presenting for open heart surgery. Milrinone has been shown to reduce pulmonary vascular resistance and pulmonary artery pressure in pediatric patients and neonates postcardiac surgery. We aimed to evaluate the postoperative outcome in such patients with three different fixed maintenance doses of milrinone. Patients were randomized into three groups. All patients received fixed bolus dose of milrinone 50 μg/kg on pump during rewarming. Following this, patients in low-dose group received infusion of milrinone at the rate of 0.375 μg/kg/min, medium-dose group received 0.5 μg/kg/min, and high-dose group received 0.75 μg/kg/min over 24 h. Heart rate, mean arterial pressure (MAP), mean airway pressure (MaP), oxygenation index (OI), and central venous pressure (CVP) were compared at baseline and 24 h postoperatively. Dose of inotropic requirement, duration of ventilatory support and Intensive Care Unit (ICU) stay were noted. MAP, MaP, OI, and CVP were comparable in all three groups postoperatively. All patients in the low-dose group required low inotropic support while 70% of patients in the high-dose group needed high inotropic support to manage episodes of hypotension (P = 0.000). Duration of ventilatory support and ICU stay in all three groups was comparable (P = 0.412, P = 0.165). Low-dose infusions while having a clinical impact were more beneficial in avoiding adverse events and decreasing inotropic requirement without affecting duration of ventilatory support and duration of ICU stay.

Identification and agreement of first turn point by mathematical analysis applied to heart rate, carbon dioxide output and electromyography

PubMed Central

Zamunér, Antonio R.; Catai, Aparecida M.; Martins, Luiz E. B.; Sakabe, Daniel I.; Silva, Ester Da

2013-01-01

Background The second heart rate (HR) turn point has been extensively studied, however there are few studies determining the first HR turn point. Also, the use of mathematical and statistical models for determining changes in dynamic characteristics of physiological variables during an incremental cardiopulmonary test has been suggested. Objectives To determine the first turn point by analysis of HR, surface electromyography (sEMG), and carbon dioxide output () using two mathematical models and to compare the results to those of the visual method. Method Ten sedentary middle-aged men (53.9±3.2 years old) were submitted to cardiopulmonary exercise testing on an electromagnetic cycle ergometer until exhaustion. Ventilatory variables, HR, and sEMG of the vastus lateralis were obtained in real time. Three methods were used to determine the first turn point: 1) visual analysis based on loss of parallelism between and oxygen uptake (); 2) the linear-linear model, based on fitting the curves to the set of data (Lin-Lin ); 3) a bi-segmental linear regression of Hinkley' s algorithm applied to HR (HMM-HR), (HMM- ), and sEMG data (HMM-RMS). Results There were no differences between workload, HR, and ventilatory variable values at the first ventilatory turn point as determined by the five studied parameters (p>0.05). The Bland-Altman plot showed an even distribution of the visual analysis method with Lin-Lin , HMM-HR, HMM-CO2, and HMM-RMS. Conclusion The proposed mathematical models were effective in determining the first turn point since they detected the linear pattern change and the deflection point of , HR responses, and sEMG. PMID:24346296

Effects of Short-Term Acclimatization at the Summit of Mt. Fuji (3776 m) on Sleep Efficacy, Cardiovascular Responses, and Ventilatory Responses.

PubMed

Horiuchi, Masahiro; Oda, Shiro; Uno, Tadashi; Endo, Junko; Handa, Yoko; Fukuoka, Yoshiyuki

2017-06-01

Horiuchi, Masahiro, Shiro Oda, Tadashi Uno, Junko Endo, Yoko Handa, and Yoshiyuki Fukuoka. Effects of short-term acclimatization at the summit of Mt. Fuji (3776 m) on sleep efficacy, cardiovascular responses, and ventilatory responses. High Alt Med Biol. 18:171-178, 2017.-We investigated the effects of a short period of acclimatization, at 3776 m on Mt. Fuji, on sleep parameters and related physiological responses. Physiological responses were assessed in seven healthy lowlander men during both daytime and sleep while at sea level (SL), as well as for three consecutive nights at high altitude (HA; 3776 m, day 1 [D1], D2, D3, and morning only of D4). Blood pressure variables, heart rate (HR), pulmonary ventilation (V E ), and breathing frequency (Bf) progressively increased each day, with significant differences between SL and HA (p < 0.05, respectively). In contrast, end-tidal PCO 2 (P ET CO 2 ) progressively decreased each day with statistical differences between SL and D3 at HA (p < 0.05). During sleep at HA, mean arterial pressure (MAP) was stable, whereas it decreased during sleep at SL. Sleep efficacy, which was assessed by actigraphy, was linearly impaired with statistical differences between SL and D3 (p < 0.05). These impairments in sleep efficacy at HA were associated with higher MAP and HR, as well as lower Bf and P ET CO 2 during the daytime (pooled data, p < 0.05, respectively). These results suggest that hypoxia-induced cardiovascular and ventilatory responses may be crucial contributors to changes in sleep efficacy at HA.

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 Five Nights under Normobaric Hypoxia on Sleep Quality.

PubMed

Hoshikawa, Masako; Uchida, Sunao; Osawa, Takuya; Eguchi, Kazumi; Arimitsu, Takuma; Suzuki, Yasuhiro; Kawahara, Takashi

2015-07-01

The purpose of this study was to evaluate the effects of five nights' sleep under normobaric hypoxia on ventilatory acclimatization and sleep quality. Seven men initially slept for six nights under normoxia and then for five nights under normobaric hypoxia equivalent to a 2000-m altitude. Nocturnal polysomnograms (PSGs), arterial blood oxygen saturation (SpO2), and respiratory events were recorded on the first and fifth nights under both conditions. The hypoxic ventilatory response (HVR), hypercapnic ventilatory response (HCVR), and resting end-tidal CO2 (resting PETCO2) were measured three times during the experimental period. The duration of slow-wave sleep (SWS: stage N3) and the whole-night delta (1-3 Hz) power of nonrapid eye movement (NREM) sleep EEG decreased on the first night under hypoxia. This hypoxia-induced sleep quality deterioration on the first night was accompanied by a lower mean and minimum SpO2, a longer time spent with SpO2 below 90% (<90% SpO2 time), and more episodes of respiratory disturbance. On the fifth night, the SWS duration and whole-night delta power did not differ between the conditions. Although the mean SpO2 under hypoxia was still lower than under normoxia, the minimum SpO2 increased, and the <90% SpO2 time and number of episodes of respiratory disturbance decreased during the five nights under hypoxia. The HVR increased and resting PETCO2 decreased after five nights under hypoxia. The results suggest that five nights under hypoxia improves the sleep quality. This may be derived from improvements of respiratory disturbances, the minimum SpO2, and <90% SpO2 time.

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

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.

Acute effects of jaw clenching using a customized mouthguard on anaerobic ability and ventilatory flows.

PubMed

Morales, Jose; Buscà, Bernat; Solana-Tramunt, Mònica; Miró, Adrià

2015-12-01

The latest findings on the ergogenic effects of a dentistry-design, bite-aligning mouthpiece require additional research to assess its impact on anaerobic ability and ventilatory parameters. This paper was aimed at determining the ergogenic acute effects of wearing a custom-made mouthpiece on oral airflow dynamics, 30-s Wingate Anaerobic Test performance parameters. Twenty-eight healthy and physically-active male subjects (age: 24.50 ± 3.32, height: 181.34 ± 7.4, weight: 78.14 ± 8.21), were voluntarily studied. The subjects were first briefed on the test protocols, and then performed the 30s Wingate test and Spirometer test. The experimental trials were performed in a random counterbalanced order. We evaluate maximum expiratory volume (VEmax L min(-1)), mean power (W kg(-1)), peak power (W kg(-1)), time to peak (s), rate to fatigue (Ws(-1)) and lactate production (mMol L(-1)), rate of perceived exertion (RPE). There were significant differences between mouthguard and no-mouthguard conditions in mean power (W kg(-1)), peak power (W kg(-1)), time to peak (s), and rate to fatigue (Ws(-1)) for the 30-s Wingate Anaerobic Test. Significantly lower lactate production (mMol L(-1)) was observed, in mouthguard condition but no significant differences were found in RPE. In airflow dynamics, the VEmax L min(-1) was significantly higher when comparing the mouthguard and the no mouthguard conditions in both forced and unforced conditions. In conclusion, wearing a customized mouthguard improves anaerobic ability and increases forced expiratory volume. This study will help practitioners improve athlete's performance in anaerobic activities where high intensity action might provoke jaw-clenching, contributing in reductions of lactate and fatigue, and improving ventilatory parameters. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

Identification and agreement of first turn point by mathematical analysis applied to heart rate, carbon dioxide output and electromyography.

PubMed

Zamunér, Antonio R; Catai, Aparecida M; Martins, Luiz E B; Sakabe, Daniel I; Da Silva, Ester

2013-01-01

The second heart rate (HR) turn point has been extensively studied, however there are few studies determining the first HR turn point. Also, the use of mathematical and statistical models for determining changes in dynamic characteristics of physiological variables during an incremental cardiopulmonary test has been suggested. To determine the first turn point by analysis of HR, surface electromyography (sEMG), and carbon dioxide output (VCO2) using two mathematical models and to compare the results to those of the visual method. Ten sedentary middle-aged men (53.9 ± 3.2 years old) were submitted to cardiopulmonary exercise testing on an electromagnetic cycle ergometer until exhaustion. Ventilatory variables, HR, and sEMG of the vastus lateralis were obtained in real time. Three methods were used to determine the first turn point: 1) visual analysis based on loss of parallelism between VCO2 and oxygen uptake (VO2); 2) the linear-linear model, based on fitting the curves to the set of VCO2 data (Lin-LinVCO2); 3) a bi-segmental linear regression of Hinkley's algorithm applied to HR (HMM-HR), VCO2 (HMM-VCO2), and sEMG data (HMM-RMS). There were no differences between workload, HR, and ventilatory variable values at the first ventilatory turn point as determined by the five studied parameters (p>0.05). The Bland-Altman plot showed an even distribution of the visual analysis method with Lin-LinVCO2, HMM-HR, HMM-VCO2, and HMM-RMS. The proposed mathematical models were effective in determining the first turn point since they detected the linear pattern change and the deflection point of VCO2, HR responses, and sEMG.

The Gravity-Loading countermeasure Skinsuit (GLCS) and its effect upon aerobic exercise performance

NASA Astrophysics Data System (ADS)

Attias, Julia; Philip, A. T. Carvil; Waldie, James; Russomano, Thais; Simon, N. Evetts; David, A. Green

2017-03-01

The Russian Pingvin suit is employed as a countermeasure to musculoskeletal atrophy in microgravity, though its 2-stage loading regime is poorly tolerated. The Gravity-Loading Countermeasure Skinsuit (GLCS) has been devised to comfortably compress the body via incrementally increasing longitudinal elastic-fibre tensions from the shoulders to the feet. We tested whether the Mk III GLCS was a feasible adjunct to sub-maximal aerobic exercise and resulting VO2Max predictions. Eight healthy subjects (5♂, 28±6 yr) performed cycle ergometry at 75% VO2Max (derived from an Astrand-Rhyming protocol) whilst wearing a GLCS and gym clothing (GYM). Ventilatory parameters, heart rate (HR), core temperature (TC), and blood lactate (BL) were recorded along with subjective perceived exertion, thermal comfort, movement discomfort and body control. Physiological and subjective responses were compared over TIME and between GYM and GLCS (ATTIRE) with 2-way repeated measures ANOVA and Wilcoxon tests respectively. Resultant VO2Max predictions were compared with paired t-tests between ATTIRE. The GLCS induced greater initial exercise ventilatory responses which stabilised by 20 min. HR and TC continued to rise from 5 min irrespective of ATTIRE, whereas BL was greater in the GLCS at 20 min. Predicted V O2Max did not differ with ATTIRE, though some observed differences in HR were noteworthy. All subjective ratings were exacerbated in the GLCS. Despite increased perception of workload and initial ventilatory augmentations, submaximal exercise performance was not impeded. Whilst predicted VO2Max did not differ, determination of actual VO2Max in the GLCS is warranted due to apparent modulation of the linear HR-VO2 relationship. The GLCS may be a feasible adjunct to exercise and potential countermeasure to unloaded-induced physiological deconditioning on Earth or in space.

Ancestry explains the blunted ventilatory response to sustained hypoxia and lower exercise ventilation of Quechua altitude natives.

PubMed

Brutsaert, Tom D; Parra, Esteban J; Shriver, Mark D; Gamboa, Alfredo; Rivera-Ch, Maria; León-Velarde, Fabiola

2005-07-01

Andean high-altitude (HA) natives have a low (blunted) hypoxic ventilatory response (HVR), lower effective alveolar ventilation, and lower ventilation (VE) at rest and during exercise compared with acclimatized newcomers to HA. Despite blunted chemosensitivity and hypoventilation, Andeans maintain comparable arterial O(2) saturation (Sa(O(2))). This study was designed to evaluate the influence of ancestry on these trait differences. At sea level, we measured the HVR in both acute (HVR-A) and sustained (HVR-S) hypoxia in a sample of 32 male Peruvians of mainly Quechua and Spanish origins who were born and raised at sea level. We also measured resting and exercise VE after 10-12 h of exposure to altitude at 4,338 m. Native American ancestry proportion (NAAP) was assessed for each individual using a panel of 80 ancestry-informative molecular markers (AIMs). NAAP was inversely related to HVR-S after 10 min of isocapnic hypoxia (r = -0.36, P = 0.04) but was not associated with HVR-A. In addition, NAAP was inversely related to exercise VE (r = -0.50, P = 0.005) and ventilatory equivalent (VE/Vo(2), r = -0.51, P = 0.004) measured at 4,338 m. Thus Quechua ancestry may partly explain the well-known blunted HVR (10, 35, 36, 57, 62) at least to sustained hypoxia, and the relative exercise hypoventilation at altitude of Andeans compared with European controls. Lower HVR-S and exercise VE could reflect improved gas exchange and/or attenuated chemoreflex sensitivity with increasing NAAP. On the basis of these ancestry associations and on the fact that developmental effects were completely controlled by study design, we suggest both a genetic basis and an evolutionary origin for these traits in Quechua.

Body temperature depression and peripheral heat loss accompany the metabolic and ventilatory responses to hypoxia in low and high altitude birds.

PubMed

Scott, Graham R; Cadena, Viviana; Tattersall, Glenn J; Milsom, William K

2008-04-01

The objectives of this study were to compare the thermoregulatory, metabolic and ventilatory responses to hypoxia of the high altitude bar-headed goose with low altitude waterfowl. All birds were found to reduce body temperature (T(b)) during hypoxia, by up to 1-1.5 degrees C in severe hypoxia. During prolonged hypoxia, T(b) stabilized at a new lower temperature. A regulated increase in heat loss contributed to T(b) depression as reflected by increases in bill surface temperatures (up to 5 degrees C) during hypoxia. Bill warming required peripheral chemoreceptor inputs, since vagotomy abolished this response to hypoxia. T(b) depression could still occur without bill warming, however, because vagotomized birds reduced T(b) as much as intact birds. Compared to both greylag geese and pekin ducks, bar-headed geese required more severe hypoxia to initiate T(b) depression and heat loss from the bill. However, when T(b) depression or bill warming were expressed relative to arterial O(2) concentration (rather than inspired O(2)) all species were similar; this suggests that enhanced O(2) loading, rather than differences in thermoregulatory control centres, reduces T(b) depression during hypoxia in bar-headed geese. Correspondingly, bar-headed geese maintained higher rates of metabolism during severe hypoxia (7% inspired O(2)), but this was only partly due to differences in T(b). Time domains of the hypoxic ventilatory response also appeared to differ between bar-headed geese and low altitude species. Overall, our results suggest that birds can adjust peripheral heat dissipation to facilitate T(b) depression during hypoxia, and that bar-headed geese minimize T(b) and metabolic depression as a result of evolutionary adaptations that enhance O(2) transport.

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.

Prenatal nicotine exposure increases hyperventilation in α4-knock-out mice during mild asphyxia.

PubMed

Avraam, Joanne; Cohen, Gary; Drago, John; Frappell, Peter B

2015-03-01

Prenatal nicotine exposure alters breathing and ventilatory responses to stress through stimulation of nicotine acetylcholine receptors (nAChRs). We tested the hypothesis that α4-containing nAChRs are involved in mediating the effects of prenatal nicotine exposure on ventilatory and metabolic responses to intermittent mild asphyxia (MA). Using open-flow plethysmography, we measured ventilation (V̇(E)) and rate of O2 consumption ( V̇(O2)) of wild-type (WT) and α4-knock-out (KO) mice, at postnatal (P) days 1-2 and 7-8, with and without prenatal nicotine exposure (6 mg kg(-1) day(-1) beginning on embryonic day 14). Mice were exposed to seven 2 min cycles of mild asphyxia (10% O2 and 5% CO2), each interspersed with 2 min of air. Compared to WT, α4 KO mice had increased air V̇(E) and V̇(O2) at P7-8, but not P1-2. Irrespective of age, genotype had no effect on the hyperventilatory response (increase in V̇(E)/V̇(O2)) to MA. At P1-2, nicotine suppressed air V̇(E) and V̇(O2) in both genotypes but did not affect the hyperventilatory response to MA. At P7-8 nicotine suppressed air V̇(E) and V̇(O2) of only α4 KO's but also significantly enhanced V̇(E) during MA (nearly double that of WT; p<0.001). This study has revealed complex effects of α4 nAChR deficiency and prenatal nicotine exposure on ventilatory and metabolic interactions and responses to stress. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

Ventilatory control sensitivity in patients with obstructive sleep apnea is sleep stage dependent.

PubMed

Landry, Shane A; Andara, Christopher; Terrill, Philip I; Joosten, Simon A; Leong, Paul; Mann, Dwayne L; Sands, Scott A; Hamilton, Garun S; Edwards, Bradley A

2018-05-01

The severity of obstructive sleep apnea (OSA) is known to vary according to sleep stage; however, the pathophysiology responsible for this robust observation is incompletely understood. The objective of the present work was to examine how ventilatory control system sensitivity (i.e. loop gain) varies during sleep in patients with OSA. Loop gain was estimated using signals collected from standard diagnostic polysomnographic recordings performed in 44 patients with OSA. Loop gain measurements associated with nonrapid eye movement (NREM) stage 2 (N2), stage 3 (N3), and REM sleep were calculated and compared. The sleep period was also split into three equal duration tertiles to investigate how loop gain changes over the course of sleep. Loop gain was significantly lower (i.e. ventilatory control more stable) in REM (Mean ± SEM: 0.51 ± 0.04) compared with N2 sleep (0.63 ± 0.04; p = 0.001). Differences in loop gain between REM and N3 (p = 0.095), and N2 and N3 (p = 0.247) sleep were not significant. Furthermore, N2 loop gain was significantly lower in the first third (0.57 ± 0.03) of the sleep period compared with later second (0.64 ± 0.03, p = 0.012) and third (0.64 ± 0.03, p = 0.015) tertiles. REM loop gain also tended to increase across the night; however, this trend was not statistically significant [F(2, 12) = 3.49, p = 0.09]. These data suggest that loop gain varies between REM and NREM sleep and modestly increases over the course of sleep. Lower loop gain in REM is unlikely to contribute to the worsened OSA severity typically observed in REM sleep, but may explain the reduced propensity for central sleep apnea in this sleep stage.

Ventilatory Responses During Submaximal Exercise in Children With Prader-Willi Syndrome.

PubMed

Hyde, Adam M; McMurray, Robert G; Chavoya, Frank A; Rubin, Daniela A

2018-02-27

Prader-Willi syndrome (PWS) is a genetic neurobehavioral disorder presenting hypothalamic dysfunction and adiposity. At rest, PWS exhibits hypoventilation with hypercapnia. We characterized ventilatory responses in children with PWS during exercise. Participants were children aged 7-12 years with PWS (n = 8) and without PWS with normal weight (NW; n = 9, body mass index ≤ 85th percentile) or obesity (n = 9, body mass index ≥ 95th percentile). Participants completed three 5-minute ambulatory bouts at 3.2, 4.0, and 4.8 km/h. Oxygen uptake, carbon dioxide output, ventilation, breathing frequency, and tidal volume were recorded. PWS had slightly higher oxygen uptake (L/min) at 3.2 km/h [0.65 (0.46-1.01) vs 0.49 (0.34-0.83)] and at 4.8 km/h [0.89 (0.62-1.20) vs 0.63 (0.45-0.97)] than NW. PWS had higher ventilation (L/min) at 3.2 km/h [16.2 (13.0-26.5) vs 11.5 (8.4-17.5)], at 4.0 km/h [16.4 (13.9-27.9) vs 12.7 (10.3-19.5)], and at 4.8 km/h [19.7 (17.4-31.8) vs 15.2 (9.5-21.6)] than NW. PWS had greater breathing frequency (breaths/min) at 3.2 km/h [38 (29-53) vs 29 (22-35)], at 4.0 km/h [39 (29-58) vs 29 (23-39)], and at 4.8 km/h [39 (33-58) vs 32 (23-42)], but similar tidal volume and ventilation/carbon dioxide output to NW. PWS did not show impaired ventilatory responses to exercise. Hyperventilation in PWS may relate to excessive neural stimulation and metabolic cost.

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 ...

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.

Cost containment and mechanical ventilation in the United States.

PubMed

Cohen, I L; Booth, F V

1994-08-01

In many ICUs, admission and discharge hinge on the need for intubation and ventilatory support. As few as 5% to 10% of ICU patients require prolonged mechanical ventilation, and this patient group consumes > or = 50% of ICU patient days and ICU resources. Prolonged ventilatory support and chronic ventilator dependency, both in the ICU and non-ICU settings, have a significant and growing impact on healthcare economics. In the United States, the need for prolonged mechanical ventilation is increasingly recognized as separate and distinct from the initial diagnosis and/or procedure that leads to hospitalization. This distinction has led to improved reimbursement under the prospective diagnosis-related group (DRG) system, and demands more precise accounting from healthcare providers responsible for these patients. Using both published and theoretical examples, mechanical ventilation in the United States is discussed, with a focus on cost containment. Included in the discussion are ventilator teams, standards of care, management protocols, stepdown units, rehabilitation units, and home care. The expanding role of total quality management (TQM) is also presented.

Hemodynamic, ventilatory, and biochemical responses of panic patients and normal controls with sodium lactate infusion and spontaneous panic attacks.

PubMed

Gaffney, F A; Fenton, B J; Lane, L D; Lake, C R

1988-01-01

Hemodynamic, ventilatory, and biochemical variables were measured in ten healthy adults and ten panic patients during infusion of 0.5 mol/L of sodium lactate. Physical activity, fitness level, and ambulatory electrocardiograms were also recorded. Lactate infusion doubled cardiac output, increased blood lactate levels by sixfold, and produced hypernatremia, hypocalcemia, and decreased serum bicarbonate levels in both groups but raised arterial pressure only in the patients. The patients hyperventilated before and during the infusion. Physiological responses and somatic complaints with the infusion differed little between the groups, but emotional complaints were six times more frequent among the panic patients. Eight patients but no control subjects interpreted their symptoms as a panic attack. Heart rate increased with only 14 of 31 recorded spontaneous outpatient panic attacks. Sodium lactate infusions appear to produce panic by mimicking the physiology of spontaneous panic. Treatment with cardioactive agents is not indicated in the absence of cardiopulmonary or autonomic nervous system abnormalities.

Diaphragm Plasticity in Aging and Disease: Therapies for Muscle Weakness go from Strength to Strength.

PubMed

Greising, Sarah M; Ottenheijm, Coen A C; O'Halloran, Ken D; Barreiro, Esther

2018-04-19

The diaphragm is the main inspiratory muscle and is required to be highly active throughout the lifespan. The diaphragm muscle must be able to produce and sustain various behaviors that range from ventilatory to non-ventilatory such as those required for airway maintenance and clearance. Throughout the lifespan various circumstances and conditions may affect the ability of the diaphragm muscle to generate requisite forces and in turn the diaphragm muscle may undergo significant weakness and dysfunction. For example, hypoxic stress, critical illness, cancer cachexia, chronic obstructive pulmonary disorder (COPD), and age-related sarcopenia all represent conditions in which significant diaphragm muscle dysfunction exits. This perspective review article presents several interesting topics involving diaphragm plasticity in aging and disease that were presented at the International Union of Physiological Sciences (IUPS) Conference in 2017.This review seeks to maximize the broad and collective research impact on diaphragm muscle dysfunction in the search for transformative treatment approaches to improve the diaphragm muscle health during aging and disease.

Exercise responses in patients with chronically high creatine kinase levels.

PubMed

Cooper, Christopher B; Dolezal, Brett A; Neufeld, Eric V; Shieh, Perry; Jenner, John R; Riley, Marshall

2017-08-01

Elevated serum creatine kinase (CK) is often taken to reflect muscle disease, but many individuals have elevated CK without a specific diagnosis. How elevated CK reflects muscle metabolism during exercise is not known. Participants (46 men, 48 women) underwent incremental exercise testing to assess aerobic performance, cardiovascular response, and ventilatory response. Serum lactate, ammonia, and CK were measured at rest, 4 minutes into exercise, and 2 minutes into recovery. High-CK and control subjects demonstrated similar aerobic capacities and cardiovascular responses to incremental exercise. Those with CK ≥ 300 U/L exhibited significantly higher lactate and ammonia levels after maximal exercise, together with increased ventilatory responses, whereas those with CK ≥200 U/L but ≤ 300 U/L did not. We recommend measurement of lactate and ammonia profiles during a maximal incremental exercise protocol to help identify patients who warrant muscle biopsy to rule out myopathy. Muscle Nerve 56: 264-270, 2017. © 2016 Wiley Periodicals, Inc.

Occlusion pressures in men rebreathing CO2 under methoxyflurane anesthesia.

PubMed

Derenne, J P; Couture, J; Iscoe, S; Whitelaw, A; Milic-Emili, J

1976-05-01

The effect of general anesthesia on control of breathing was studied by CO2 rebreathing and occlusion pressure measurements in six normal human subjects under methoxyflurane anesthesia. CO2 was found to increase the amplitude of the occlusion pressure wave without changing its shape, so that CO2 responses in terms of the occlusion pressure developed 100 ms after the onset of inspiration (Po/0.1) gave results equivalent to the responses in terms of Po/1.o or any other parameter of the pressure wave. Methoxyflurane depressed the ventilatory response to CO2 but not the occlusion pressure response, implying that the most important action of the anesthetic was to increase the effective elastance of the respiratory system rather than to depress the respiratory centers. The elastance was further increased by CO2, and this mechanical change had the effect of shifting the "apneic threshold" extrapolated from the ventilatory response curve to a lower PAco2. Frequency of breathing, inspiratory and expiratory times were not altered by CO2 in anesthetized subjects.

Isoflurane and Ketamine Anesthesia have Different Effects on Ventilatory Pattern Variability in Rats

PubMed Central

Chung, Augustine; Fishman, Mikkel; Dasenbrook, Elliot C.; Loparo, Kenneth A.; Dick, Thomas E.; Jacono, Frank J.

2013-01-01

We hypothesize that isoflurane and ketamine impact ventilatory pattern variability (VPV) differently. Adult Sprague-Dawley rats were recorded in a whole-body plethysmograph before, during and after deep anesthesia. VPV was quantified from 60-s epochs using a complementary set of analytic techniques that included constructing surrogate data sets that preserved the linear structure but disrupted nonlinear deterministic properties of the original data. Even though isoflurane decreased and ketamine increased respiratory rate, VPV as quantified by the coefficient of variation decreased for both anesthetics. Further, mutual information increased and sample entropy decreased and the nonlinear complexity index (NLCI) increased during anesthesia despite qualitative differences in the shape and period of the waveform. Surprisingly mutual information and sample entropy did not change in the surrogate sets constructed from isoflurane data, but in those constructed from ketamine data, mutual information increased and sample entropy decreased significantly in the surrogate segments constructed from anesthetized relative to unanesthetized epochs. These data suggest that separate mechanisms modulate linear and nonlinear variability of breathing. PMID:23246800

Muscimol microinjected in the arcuate nucleus affects metabolism, body temperature & ventilation.

PubMed

Schlenker, Evelyn H

2016-06-15

Effects of microinjection of 2 doses of γ-aminobutyric acid (GABA)A receptor agonist, muscimol (M), into the hypothalamic arcuate nucleus on oxygen consumption and control of ventilation over time and body temperature (BT) at the end of the experiment were compared in adult male and female rats. Relative to cerebrospinal fluid (CSF, 0 nmol), BT was decreased only in male rats with both doses of M, while in female rats, the 5 nmol dose depressed oxygen consumption. Ventilation was depressed by 5 nmol M in male and 10 nmol M in female rats by decreasing tidal volume. M did not affect the ventilatory response of male or female rats to hypoxia, whereas in females 5 and 10 nmol M and in males 10 nmol M depressed the ventilatory response to hypercapnia. Thus, in rats GABAA receptors in the arcuate nucleus modulate BT, oxygen consumption, and ventilation in air and in response to hypercapnia in a sexually dimorphic manner. Copyright © 2016 Elsevier B.V. All rights reserved.

[Aerophagia due to noninvasive mechanical ventilation: a first manifestation of silent gastric carcinoma].

PubMed

Mayoralas Alises, S; Gómez Mendieta, M A; Díaz Lobato, S

2003-07-01

Noninvasive mechanical ventilation (NIV) techniques have proven useful in treating patients with respiratory insufficiency of various etiologies. The problems most frequently associated with this ventilatory technique are the appearance of nasal and oropharyngeal dryness, pressure sores where the nasal mask touches the skin, ocular irritation due to air leakage and epistaxis. Aerophagia appears in up to half the patients with NIV and may lead to discontinuing treatment. Drugs that accelerate gastrointestinal transit, changes in the respirator settings or changing the ventilatory modality may help to ameliorate the problem. When the symptoms arising from abdominal distension due to NIV are intense and persistent, the coexistence of an underlying abdominal pathology must be ruled out. We report the cases of two patients with these characteristics in whom gastroscopy revealed gastric carcinoma. We think that patients with persistent symptoms of aerophagia that cannot be controlled by the usual measures should undergo endoscopic exploration to rule out silent gastric disease.

Respiratory symptoms and pulmonary function impairment among detergent plant workers in Jos, Northern Nigeria.

PubMed

Babashani, M; Iliyasu, Z; Ukoli, C O

2008-01-01

The industrial process of detergent production could be deleterious to lung function. This study describes respiratory symptoms and ventilatory function impairment among detergent workers in Jos, Northern Nigeria. Two hundred detergent plant workers and controls were studied for the presence of respiratory symptoms and ventilatory function impairment using the MRC questionnaire and Spirometry. A significantly higher proportion of exposed detergent workers 178 (87.0%) reported respiratory symptoms compared to 52 (26.0%) controls [OR=23; 95% CI=12.9-41.3] (P<0.001). Commonest symptoms include rhinitis (57.5% versus 11.0%) and cough (48.5% versus 15%). Symptoms were most prevalent in the packaging section. FEV1, FVC and PEFR were significantly reduced among exposed detergent workers. Similarly, the predicted values of PEFR, FVC and FEV1, were significantly reduced among smokers (P<0. 001). Respiratory symptoms are highly prevalent among detergent workers. This was associated with impaired pulmonary function. Protective equipment and periodic lung function tests could reduce these effects.

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

Sleep and respiration in microgravity

NASA Technical Reports Server (NTRS)

Prisk, G. K.

1998-01-01

Sleep studies conducted during the STS-90 Neurolab mission are explored. The relationship between sleep, melatonin, and circadian phase is reviewed. The study contained both sleep and awake components. The objectives of the sleep component were to test five hypotheses: that circadian rhythms of core body temperature and urinary melatonin are synchronized to required sleep-wake schedules, that spaceflight results in substantial disruption of sleep, that the pattern of chest and abdominal wall motion alters during the different sleep stages in microgravity, that arterial oxygen saturation is reduced during some stages of sleep in microgravity, and that pre-sleep administration of melatonin during microgravity results in improved sleep quality. The awake component tested three hypotheses: that ventilatory response to carbon dioxide is increased during exposure to microgravity and that this exacerbates sleep disruption, that ventilatory response to hypoxia is increased by exposure to microgravity, and that the improved sleep resulting from the pre-sleep administration of melatonin enhances next day cognition when compared to placebo.

Characterization of Ventilatory Modes in Dragonfly Nymph

NASA Astrophysics Data System (ADS)

Roh, Chris; Saxton-Fox, Theresa; Gharib, Morteza

2013-11-01

A dragonfly nymph's highly modified hindgut has multiple ventilatory modes: hyperventilation (i.e. jet propulsion), gulping ventilation (extended expiratory phase) and normal ventilation. Each mode involves dynamic manipulation of the exit diameter and pressure. To study the different fluid dynamics associated with the three modes, Anisopteran larvae of the family Aeshnidae were tethered onto a rod for flow visualization. The result showed distinct flow structures. The hyperventilation showed a highly turbulent and powerful jet that occurred at high frequency. The gulping ventilation produced a single vortex at a moderate frequency. The normal ventilation showed two distinct vortices, a low-Reynolds number vortex, followed by a high-Reynolds number vortex. Furthermore, a correlation of the formation of the vortices with the movement of the sternum showed that the dragonfly is actively controlling the timing and the speed of the vortices to have them at equal distance from the jet exit at the onset of inspiration. This behavior prevents inspiration of the oxygen deficient expirated water, resulting in the maximization of the oxygen intake. Supported by NSF GRFP.

21 CFR 868.2375 - Breathing frequency monitor.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Breathing frequency monitor. 868.2375 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2375 Breathing frequency monitor. (a) Identification. A breathing (ventilatory) frequency monitor is a device intended to measure or monitor a patient...

Antioxidants prevent depression of the acute hypoxic ventilatory response by subanaesthetic halothane in men

PubMed Central

Teppema, Luc J; Nieuwenhuijs, Diederik; Sarton, Elise; Romberg, Raymonda; Olievier, Cees N; Ward, Denham S; Dahan, Albert

2002-01-01

We studied the effect of the antioxidants (AOX) ascorbic acid (2 g, I.V.) and α-tocopherol (200 mg, P.O.) on the depressant effect of subanaesthetic doses of halothane (0.11 % end-tidal concentration) on the acute isocapnic hypoxic ventilatory response (AHR), i.e. the ventilatory response upon inhalation of a hypoxic gas mixture for 3 min (leading to a haemoglobin saturation of 82 ± 1.8 %) in healthy male volunteers. In the first set of protocols, two groups of eight subjects each underwent a control hypoxic study, a halothane hypoxic study and finally a halothane hypoxic study after pretreatment with AOX (study 1) or placebo (study 2). Halothane reduced the AHR by more than 50 %, from 0.79 ± 0.31 to 0.36 ± 0.14 l min−1 %−1 in study 1 and from 0.79 ± 0.40 to 0.36 ± 0.19 l min−1 %−1 in study 2, P < 0.01 for both. Pretreatment with AOX prevented this depressant effect of halothane in the subjects of study 1 (AHR returning to 0.77 ± 0.32 l min−1 %−1, n.s. from control), whereas placebo (study 2) had no effect (AHR remaining depressed at 0.36 ± 0.27 l min−1 %−1, P < 0.01 from control). In a second set of protocols, two separate groups of eight subjects each underwent a control hypoxic study, a sham halothane hypoxic study and finally a sham halothane hypoxic study after pretreatment with AOX (study 3) or placebo (study 4). In studies 3 and 4, sham halothane did not modify the control hypoxic response, nor did AOX (study 3) or placebo (study 4). The 95 % confidence intervals for the ratio of hypoxic sensitivities, (AOX + halothane):halothane in study 1 and (AOX - sham halothane):sham halothane in study 3, were [1.7, 2.6] and [1.0, 1.2], respectively. Because the antioxidants prevented the reduction of the acute hypoxic response by halothane, we suggest that this depressant effect may be caused by reactive species produced by a reductive metabolism of halothane during hypoxia or that a change in redox state of carotid body cells by the antioxidants prevented or changed the binding of halothane to its effect site. Our findings may also suggest that reactive species have an inhibiting effect on the acute hypoxic ventilatory response. PMID:12411535

Information disclosure and decision-making: the Middle East versus the Far East and the West.

PubMed

Mobeireek, A F; Al-Kassimi, F; Al-Zahrani, K; Al-Shimemeri, A; al-Damegh, S; Al-Amoudi, O; Al-Eithan, S; Al-Ghamdi, B; Gamal-Eldin, M

2008-04-01

to assess physicians' and patients' views in Saudi Arabia (KSA) towards involving the patient versus the family in the process of diagnosis disclosure and decision-making, and to compare them with views from the USA and Japan. A self-completion questionnaire (used previously to study these issues in Japan and the USA) was translated to Arabic and validated. Physicians (n = 321) from different specialties and ranks and patients (n = 264) in a hospital or attending outpatient clinics from 6 different regions in KSA. In the case of a patient with incurable cancer, 67% of doctors and 51% of patients indicated that they would inform the patient in preference to the family of the diagnosis (p = 0.001). Assuming the family already knew, 56% of doctors and 49% of patients would tell the patient even if family objected (p NS). However, in the case of HIV infection, 59% of physicians and 81% of patients would inform the family about HIV status without the patient's consent (p = 0.001). With regards to withholding ventilatory support, about 50% of doctors and over 60% of patients supported the use of mechanical ventilation in a patient with advanced cancer, regardless of the wishes of the patient or the family. Finally, the majority of doctors and patients (>85%) were against assisted suicide. Although there was more recognition for a patient's autonomy amongst physicians, most patients preferred a family centred model of care. Views towards information disclosure were midway between those of the USA and Japan. Distinctively, however, decisions regarding life prolonging therapy and assisted suicide were not influenced to a great extent by wishes of the patient or family, but more likely by religious beliefs.

Short-term and long-term prognostic outcomes of patients with ST-segment elevation myocardial infarction complicated by profound cardiogenic shock undergoing early extracorporeal membrane oxygenator-assisted primary percutaneous coronary intervention.

PubMed

Chung, Sheng-Ying; Tong, Meng-Shen; Sheu, Jiunn-Jye; Lee, Fan-Yen; Sung, Pei-Hsun; Chen, Chien-Jen; Yang, Cheng-Hsu; Wu, Chiung-Jen; Yip, Hon-Kan

2016-11-15

This study investigated the 30-day and long-term prognostic outcomes in patients with ST-segment elevation myocardial infarction (STEMI) complicated with profound cardiogenic shock (CS) undergoing early routine extracorporeal membrane oxygenator (ECMO)-assisted primary percutaneous coronary intervention (PCI). Between December 2005 and December 2014, 65 consecutive STEMI patients with profound CS underwent routine ECMO-supported primary PCI. The incidences of acute pulmonary edema, respiratory failure with requirement of mechanical ventilatory support upon presentation, and 30-day mortality rate were 100%, 95.4%, and 43.1%, respectively. The duration of hospitalization, mean long-term follow-up, and survival rate were 32.1±53.1 (days), 733.6±986.7 (days), and 32.3%, respectively. The mean APACHE score (32.6±8.3 vs. 28.5±7.5), peak serum creatinine level (4.3±2.4 vs. 1.7±1.2mg/dL), incidences of failed ECMO weaning (57.1% vs. 0%), successful ECMO weaning but in-hospital death (40.0% vs. 0%) were significantly lower in 30-day survivors than those in non-survivors (all p<0.05), whereas final thrombolysis in myocardial infarction (TIMI)-3 flow [53.6% vs. 91.9%] showed an opposite pattern compared to that of APACHE score in the two groups (p<0.02). Multivariate analysis demonstrated that unsuccessful reperfusion, failed ECMO weaning, and peak creatinine level were independent predictors of 30-day mortality (all p<0.01). Early ECMO-supported primary PCI in STEMI patients with profound CS was feasible as a life-saving strategy with acceptable 30-day and long-term prognostic outcomes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Speaking-Related Dyspnea in Healthy Adults

ERIC Educational Resources Information Center

Hoit, Jeannette D.; Lansing, Robert W.; Perona, Kristen E.

2007-01-01

Purpose: To reveal the qualities and intensity of speaking-related dyspnea in healthy adults under conditions of high ventilatory drive, in which the behavioral and metabolic control of breathing must compete. Method: Eleven adults read aloud while breathing different levels of inspired carbon dioxide (CO[subscript 2]). After the highest level,…

21 CFR 868.2375 - Breathing frequency monitor.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Breathing frequency monitor. 868.2375 Section 868.2375 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2375 Breathing frequency monitor. (a) Identification. A breathing (ventilatory)...

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 ...

Evaluation of the Virtual Physiology of Exercise Laboratory Program

ERIC Educational Resources Information Center

Dobson, John L.

2009-01-01

The Virtual Physiology of Exercise Laboratory (VPEL) program was created to simulate the test design, data collection, and analysis phases of selected exercise physiology laboratories. The VPEL program consists of four modules: (1) cardiovascular, (2) maximal O[subscript 2] consumption [Vo[subscript 2max], (3) lactate and ventilatory thresholds,…

[New use of pulse-oximeter as a prophylactic Stimulator to the wearer and a lifesaving tools for prevention of hypoxic mishaps].

PubMed

Morioka, Tohru; Terasaki, Hidenori

2014-03-01

Pulse-oximeter has been widely used for the clinical assessment of physical status of a patient and as an alarming tool of hypoxia to medical personnel at the bedside or in the observation center. However, it has never been used for direct stimulation of the wearer. We considered innovation of pulse-oximeter as a prophylactic alarm-oximeter for the wearer. If SPO2 goes down to unfavorable level, the alarm-oximeter starts to send signal through a control box to a stimulator, such as an electrical nerve stimulator, a cold thermal tip, or mechanical device like a vibrator or compressor. The dermal stimulator is usually fixed to the right or left wrist with a Velcro band. The control box is affixed to the wristband by using Velcro. The alarm may be sent to an earphone or speaker with a verbal command like "take a deep breath". Alarm-oximeter will be combined to an oxygen inhaler or mechanical ventilatory assist device, or a drug administration system through electric line or wireless transmitter to start or change its function before the arrival of medical personnel. It will prevent hypoxic mishaps during medical intervention or sleep apnea syndrome. It will be also applicable to stop snoring.

Outcome of Concurrent Occult Hemothorax and Pneumothorax in Trauma Patients Who Required Assisted Ventilation

PubMed Central

Mahmood, Ismail; Tawfeek, Zainab; El-Menyar, Ayman; Zarour, Ahmad; Afifi, Ibrahim; Kumar, Suresh; Latifi, Rifat; Al-Thani, Hassan

2015-01-01

Background. The management and outcomes of occult hemopneumothorax in blunt trauma patients who required mechanical ventilation are not well studied. We aimed to study patients with occult hemopneumothorax on mechanical ventilation who could be carefully managed without tube thoracostomy. Methods. Chest trauma patients with occult hemopneumothorax who were on mechanical ventilation were prospectively evaluated. The presence of hemopneumothorax was confirmed by CT scanning. Hospital length of stay, complications, and outcome were recorded. Results. A total of 56 chest trauma patients with occult hemopneumothorax who were on ventilatory support were included with a mean age of 36 ± 13 years. Hemopneumothorax was managed conservatively in 72% cases and 28% underwent tube thoracostomy as indicated. 29% of patients developed pneumonia, 16% had Acute Respiratory Distress Syndrome (ARDS), and 7% died. Thickness of hemothorax, duration of mechanical ventilation, and development of ARDS were significantly associated with tube thoracostomy in comparison to no-chest tube group. Conclusions. The majority of occult hemopneumothorax can be carefully managed without tube thoracostomy in patients who required positive pressure ventilation. Tube thoracotomy could be restricted to those who had evidence of increase in the size of the hemothorax or pneumothorax on follow-up chest radiographs or developed respiratory compromise. PMID:25785199

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.

Central Hypoventilation: A Case Study of Issues Associated with Travel Medicine and Respiratory Infection.

PubMed

Hon, Kam Lun; Leung, Alexander K C; Li, Albert M C; Ng, Daniel K K

2015-01-01

Aim. We presented the case of a child with central hypoventilation syndrome (CHS) to highlight issues that need to be considered in planning long-haul flight and problems that may arise during the flight. Case. The pediatric intensive care unit (PICU) received a child with central hypoventilation syndrome (Ondine's curse) on nocturnal ventilatory support who travelled to Hong Kong on a make-a-wish journey. He was diagnosed with central hypoventilation and had been well managed in Canada. During a long-haul aviation travel, he developed respiratory symptoms and desaturations. The child arrived in Hong Kong and his respiratory symptoms persisted. He was taken to a PICU for management. The child remained well and investigations revealed no pathogen to account for his respiratory infection. He went on with his make-a-wish journey. Conclusions. Various issues of travel medicine such as equipment, airline arrangement, in-flight ventilatory support, travel insurance, and respiratory infection are explored and discussed. This case illustrates that long-haul air travel is possible for children with respiratory compromise if anticipatory preparation is timely arranged.

Lung function in retired coke oven plant workers.

PubMed Central

Chau, N; Bertrand, J P; Guenzi, M; Mayer, L; Téculescu, D; Mur, J M; Patris, A; Moulin, J J; Pham, Q T

1992-01-01

Lung function was studied in 354 coke oven plant workers in the Lorraine collieries (Houillères du Bassin de Lorraine, France) who retired between 1963 and 1982 and were still alive on 1 January 1988. A spirometric examination was performed on 68.4% of them in the occupational health service. Occupational exposure to respiratory hazards throughout their career was retraced for each subject. No adverse effect of occupational exposure on ventilatory function was found. Ventilatory function was, however negatively linked with smoking and with the presence of a respiratory symptom or discrete abnormalities visible on pulmonary x ray films. The functional values were mostly slightly lower than predicted values and the most reduced index was the mean expiratory flow, FEF25-75%. The decrease in forced expiratory volume in one second (FEV1) was often parallel to that in forced vital capacity (FVC), but it was more pronounced for subjects who had worked underground, for smokers of more than 30 pack-years, and for subjects having a respiratory symptom. Pulmonary function indices were probably overestimated because of the exclusion of deceased subjects and the bias of the participants. PMID:1599869

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.

Influence of cycling history on the ventilatory response to cycle-ergometry in humans: a role for respiratory memory?

PubMed

Cathcart, Andrew J; Whipp, Brian J; Turner, Anthony P; Wilson, John; Ward, Susan A

2010-01-01

The ventilatory (V' E) mechanisms subserving stability of alveolar and arterial PCO2 (PACO2, PaCO2) during moderate exercise (< lactate threshold, thetaL) remain controversial. As long-term modulation has been argued to be an important contributor to this control process, we proposed that subjects with no experience of cycling (NEx) might provide insight into this issue. With no exercise familiarization, 9 sedentary NEx subjects and 9 age-, sex-, and activity-matched controls (C) who had cycled regularly for recreational purposes since childhood completed a square-wave (6-min stage) cycle-ergometry test: 10 W-WR1-WR2-WR1-10 W; WR1 range 25-45 W, WR2 range 50-90 W. WRs were subsequently confirmed to

Impact of air pollutants on athletic performance

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

Pierson, W.E.

Human controlled and observational studies both lead to the conclusion of air pollution adversely affecting athletic performance during training and competition. The dosage of various air pollutants during exercise is much higher due to the marked increase in ventilatory rate and concomitant nasal and oral breathing. This is particularly true for sulfur dioxide which is a highly water-soluble gas and is normally absorbed in the upper airway during nasal breathing. With heavy exercise, oral pharyngeal breathing is the predominant mode of breathing and much larger amounts of sulfur dioxide are delivered to the lower airway resulting in significant impact uponmore » the lower respiratory tract. More recently, several controlled human studies have shown that a combination of exercise and air pollutants such as ozone (O3) or sulfur dioxides (SO2) cause a significant increase in bronchoconstriction and air flow obstruction when compared to the same exposure at rest. In strenuous athletic competition such as the Olympic Games where small increments of time often determine the ultimate success of athletes, the impact of air pollutants and subsequent adverse ventilatory changes can affect athletic performance. 62 references.« less

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).

Ventilatory response to carbon dioxide in young athletes: a family study.

PubMed

Saunders, N A; Leeder, S R; Rebuck, A S

1976-04-01

Ventilatory response to carbon dioxide (deltaVE/deltaPCO2) was measured in 23 teenage swimmers chosen by their coach for their potential for future athletic success. Siblings and parents of these swimmers were also studied. We found a strong relation between siblings' de;taVE/DELTAPCO2, whether or not they were swimmers (r=0.71, P less than 0.01). A weaker relationship was found between mother's and children's deltaVE/DELTAPCO2 (r==0.39, P less than 0.01). No association was found between swimming training and deltaVE/deltaPCO2. One swimmer 12 years of age had an extremely low deltaVE/PCO2 (0.42 liter per min per mm Hg) She was the only swimmer among these 23 potential champions to achieve international success in endurance events in the 2 years after the study. We concluded that family factors are important determinants of a subject's deltaVE/PCO2 and suggest that measurement of this aspect of chemical drive to breathing in young athletes may help identify those most likely to succeed in endurance events.

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.

Classic conditioning of the ventilatory responses in rats.

PubMed

Nsegbe, E; Vardon, G; Perruchet, P; Gallego, J

1997-10-01

Recent authors have stressed the role of conditioning in the control of breathing, but experimental evidence of this role is still sparse and contradictory. To establish that classic conditioning of the ventilatory responses can occur in rats, we performed a controlled experiment in which a 1-min tone [conditioned stimulus (CS)] was paired with a hypercapnic stimulus [8.5% CO2, unconditioned stimulus (US)]. The experimental group (n = 9) received five paired CS-US presentations, followed by one CS alone to test conditioning. This sequence was repeated six times. The control group (n = 7) received the same number of CS and US, but each US was delivered 3 min after the CS. We observed that after the CS alone, breath duration was significantly longer in the experimental than in the control group and mean ventilation was significantly lower, thus showing inhibitory conditioning. This conditioning may have resulted from the association between the CS and the inhibitory and aversive effects of CO2. The present results confirmed the high sensitivity of the respiratory controller to conditioning processes.

An Improved Dynamic Model for the Respiratory Response to Exercise

PubMed Central

Serna, Leidy Y.; Mañanas, Miguel A.; Hernández, Alher M.; Rabinovich, Roberto A.

2018-01-01

Respiratory system modeling has been extensively studied in steady-state conditions to simulate sleep disorders, to predict its behavior under ventilatory diseases or stimuli and to simulate its interaction with mechanical ventilation. Nevertheless, the studies focused on the instantaneous response are limited, which restricts its application in clinical practice. The aim of this study is double: firstly, to analyze both dynamic and static responses of two known respiratory models under exercise stimuli by using an incremental exercise stimulus sequence (to analyze the model responses when step inputs are applied) and experimental data (to assess prediction capability of each model). Secondly, to propose changes in the models' structures to improve their transient and stationary responses. The versatility of the resulting model vs. the other two is shown according to the ability to simulate ventilatory stimuli, like exercise, with a proper regulation of the arterial blood gases, suitable constant times and a better adjustment to experimental data. The proposed model adjusts the breathing pattern every respiratory cycle using an optimization criterion based on minimization of work of breathing through regulation of respiratory frequency. PMID:29467674

Corticosteroid therapy in intensive care unit patients with PCR-confirmed influenza A(H1N1) infection in Finland.

PubMed

Linko, R; Pettilä, V; Ruokonen, E; Varpula, T; Karlsson, S; Tenhunen, J; Reinikainen, M; Saarinen, K; Perttilä, J; Parviainen, I; Ala-Kokko, T

2011-09-01

To evaluate the incidence, treatment, and outcome of influenza A(H1N1) in Finnish intensive care units (ICUs) with special reference to corticosteroid treatment. During the H1N1 outbreak in Finland between 11 October and 31 December 2009, we prospectively evaluated all consecutive ICU patients with high suspicion of or confirmed pandemic influenza A(H1N1) infection. We assessed severity of acute disease and daily organ dysfunction. Ventilatory support and other concomitant treatments were evaluated and recorded daily throughout the ICU stay. The primary outcome was hospital mortality. During the 3-month period altogether 132 ICU patients were tested polymerase chain reaction-positive for influenza A(H1N1). Of these patients, 78% needed non-invasive or invasive ventilatory support. The median (interquartile) length of ICU stay was 4 [2-12] days. Hospital mortality was 10 of 132 [8%, 95% confidence interval (CI) 3-12%]. Corticosteroids were administered to 72 (55%) patients, but rescue therapies except prone positioning were infrequently used. Simplified Acute Physiology Score II and Sequential Organ Failure Assessment scores in patients with and without corticosteroid treatment were 31 [24-36] and 6 [2-8] vs. 22 [5-30] and 3 [2-6], respectively. The crude hospital mortality was not different in patients with corticosteroid treatment compared to those without: 8 of 72 (11%, 95% CI 4-19%) vs. 2 of 60 (3%, 95% CI 0-8%) (P = 0.11). The majority of H1N1 patients in ICUs received ventilatory support. Corticosteroids were administered to more than half of the patients. Despite being more severely ill, patients given corticosteroids had comparable hospital outcome with patients not given corticosteroids. © 2011 The Authors Acta Anaesthesiologica Scandinavica © 2011 The Acta Anaesthesiologica Scandinavica Foundation.

Ventilatory function in rubber processing workers: acute changes over the workshift.

PubMed

Governa, M; Comai, M; Valentino, M; Antonicelli, L; Rinaldi, F; Pisani, E

1987-02-01

When considering rubber tyre manufacturing from an occupational health viewpoint, three areas may be identified in which exposure to respirable materials are potentially harmful: the processing, curing, and talc areas. A study of the ventilatory function of the entire work force employed in the processing area in a rubber tyre manufacturing plant was undertaken to determine whether an acute reduction in lung function occurs over the course of their working shift (the plant worked a three shift system) and whether a chronic exposure to the occupational airborne contaminants causes permanent changes in lung function. The ventilatory function was measured at the worksite at the beginning and immediately after the end of the workshift. No evidence of chronic obstructive pulmonary disease was found and in most cases no significant decline in FEV1 was observed. Only one of the 79 individuals showed a moderate obstruction, measured by the ratio FEV1/FVC which gave the value of 0.55, with no variation over the shift. For non-smokers, the FVC, FEV1, and FEF25-75% were lower in those exposed for more than five years than in those exposed for five years or less. A similar pattern was also observed in the FVC and FEV1 of the smokers. None of these differences was statistically significant. Within each exposure group the pulmonary function of the smokers was lower than that of the non-smokers, but the only significant difference was found in the values of FEF25-75%. Only one man showed a decline in the FEV1/FVC ratio over the shift, but during each shift, a decrease in all the lung function tests was observed. The decrease was smallest during the first of the three shifts. These results are thought to support the hypothesis that there are acute adverse effects over an eight hour shift. Further investigations are needed to discover whether these acute changes in lung function result from a chemical stimulation or irritant receptors in the airways.

Ventilatory and Physiological Responses in Swimmers Below and Above Their Maximal Lactate Steady State.

PubMed

Espada, Mario C; Reis, Joana F; Almeida, Tiago F; Bruno, Paula M; Vleck, Veronica E; Alves, Francisco B

2015-10-01

The purpose of this study was to understand the ventilatory and physiological responses immediately below and above the maximal lactate steady-state (MLSS) velocity and to determine the relationship of oxygen uptake (VO2) kinetics parameters with performance, in swimmers. Competitive athletes (N = 12) completed in random order and on different days a 400-m all-out test, an incremental step test comprising 5 × 250- and 1 × 200-m stages and 30 minutes at a constant swimming velocity (SV) at 87.5, 90, and 92.5% of the maximal aerobic velocity for MLSS velocity (MLSSv) determination. Two square-wave transitions of 500 m, 2.5% above and below the MLSSv were completed to determine VO2 on-kinetics. End-exercise VO2 at 97.5 and 102.5% of MLSSv represented, respectively, 81 and 97% of VO2max; the latter was not significantly different from maximal VO2 (VO2max). The VO2 at MLSSv (49.3 ± 9.2 ml·kg(-1)·min(-1)) was not significantly different from the second ventilatory threshold (VT2) (51.3 ± 7.6 ml·kg(-1)·min(-1)). The velocity associated with MLSS seems to be accurately estimated by the SV at VT2 (vVT2), and vVO2max also seems to be estimated with accuracy from the central 300-m mean velocity of a 400-m trial, indicators that represent a helpful tool for coaches. The 400-m swimming performance (T400) was correlated with the time constant of the primary phase VO2 kinetics (τp) at 97.5% MLSSv, and T800 was correlated with τp in both 97.5 and 102.5% of MLSSv. The assessment of the VO2 kinetics in swimming can help coaches to build training sets according to a swimmer's individual physiological response.

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.

A decrease in nasal CO2 stimulates breathing in the tegu lizard.

PubMed

Coates, E L; Furilla, R A; Ballam, G O; Bartlett, D

1991-10-01

Tegu lizards decrease ventilatory frequency (f) when constant CO2, as low as 0.4%, is delivered to the nasal cavities. In contrast, CO2, as high as 6%, pulsed into the nasal cavities during the expiratory phase of the breathing cycle does not alter f. The purpose of the present study was to investigate further the effect of nasal CO2 pattern on f in tegu lizards. Specifically, we tested: (1) whether f was affected by CO2 delivered to the nasal cavities during the inspiratory phase of the breathing cycle, and (2) whether pulsed decreases in nasal CO2 from 4% to 2% and from 4% to 0% would remove the f inhibition caused by constant nasal CO2. Ventilation was measured using a pneumotachograph and pressure transducer in-line with an endotracheal T-tube inserted through the glottis. CO2 was delivered to the nasal cavities through small tubes inserted into the external nares. Ventilatory frequency was not significantly altered when 4% CO2 was pulsed into the nasal cavities during inspiration. Dropping the CO2 in the nasal cavities from 4% to 0% at either 15 cycles/min (0.25 Hz) or for one cycle stimulated breathing. There was no significant difference between the f response to a drop in CO2 from 4% to 0% and that to a drop in CO2 from 4% to 2%. The failure to link the phasic CO2 ventilatory response to a phase in the respiratory cycle indicates that the nasal CO2 receptors do not participate in the breath-by-breath regulation of breathing in these lizards. The observation that small decreases in nasal CO2 abolished the f inhibition caused by constant nasal CO2 provides further evidence for the ability of the nasal CO2 receptors to distinguish between pulsed and constant CO2.

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.

Red Spinach Extract Increases Ventilatory Threshold during Graded Exercise Testing

PubMed Central

Kephart, Wesley C.; Holland, Angelia M.; Pascoe, David D.; Roberts, Michael D.

2017-01-01

Background: We examined the acute effect of a red spinach extract (RSE) (1000 mg dose; ~90 mg nitrate (NO3−)) on performance markers during graded exercise testing (GXT). Methods: For this randomized, double-blind, placebo (PBO)-controlled, crossover study, 15 recreationally-active participants (aged 23.1 ± 3.3 years; BMI: 27.2 ± 3.7 kg/m2) reported >2 h post-prandial and performed GXT 65–75 min post-RSE or PBO ingestion. Blood samples were collected at baseline (BL), pre-GXT (65–75 min post-ingestion; PRE), and immediately post-GXT (POST). GXT commenced with continuous analysis of expired gases. Results: Plasma concentrations of NO3− increased PRE (+447 ± 294%; p < 0.001) and POST (+378 ± 179%; p < 0.001) GXT with RSE, but not with PBO (+3 ± 26%, −8 ± 24%, respectively; p > 0.05). No effect on circulating nitrite (NO2−) was observed with RSE (+3.3 ± 7.5%, +7.7 ± 11.8% PRE and POST, respectively; p > 0.05) or PBO (−0.5 ± 7.9%, −0.2 ± 8.1% PRE and POST, respectively; p > 0.05). When compared to PBO, there was a moderate effect of RSE on plasma NO2− at PRE (g = 0.50 [−0.26, 1.24] and POST g = 0.71 [−0.05, 1.48]). During GXT, VO2 at the ventilatory threshold was significantly higher with RSE compared to PBO (+6.1 ± 7.3%; p < 0.05), though time-to-exhaustion (−4.0 ± 7.7%; p > 0.05) and maximal aerobic power (i.e., VO2 peak; −0.8 ± 5.6%; p > 0.05) were non-significantly lower with RSE. Conclusions: RSE as a nutritional supplement may elicit an ergogenic response by delaying the ventilatory threshold. PMID:29910440

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.

Comparison of the metabolic and ventilatory response to hypoxia and H2S in unsedated mice and rats.

PubMed

Haouzi, Philippe; Bell, Harold J; Notet, Veronique; Bihain, Bernard

2009-07-31

Hypoxia alters the control of breathing and metabolism by increasing ventilation through the arterial chemoreflex, an effect which, in small-sized animals, is offset by a centrally mediated reduction in metabolism and respiration. We tested the hypothesis that hydrogen sulfide (H(2)S) is involved in transducing these effects in mammals. The rationale for this hypothesis is twofold. Firstly, inhalation of a 20-80 ppm H(2)S reduces metabolism in small mammals and this effect is analogous to that of hypoxia. Secondly, endogenous H(2)S appears to mediate some of the cardio-vascular effects of hypoxia in non-mammalian species. We, therefore, compared the ventilatory and metabolic effects of exposure to 60 ppm H(2)S and to 10% O(2) in small and large rodents (20g mice and 700g rats) wherein the metabolic response to hypoxia has been shown to differ according to body mass. H(2)S and hypoxia produced profound depression in metabolic rate in the mice, but not in the large rats. The depression was much faster with H(2)S than with hypoxia. The relative hyperventilation produced by hypoxia in the mice was replaced by a depression with H(2)S, which paralleled the drop in metabolic rate. In the larger rats, ventilation was stimulated in hypoxia, with no change in metabolism, while H(2)S affected neither breathing nor metabolism. When mice were simultaneously exposed to H(2)S and hypoxia, the stimulatory effects of hypoxia on breathing were abolished, and a much larger respiratory and metabolic depression was observed than with H(2)S alone. H(2)S had, therefore, no stimulatory effect on the arterial chemoreflex. The ventilatory depression during hypoxia and H(2)S in small mammals appears to be dependent upon the ability to decrease metabolism.

Impact of neuraminidase inhibitors on influenza A(H1N1)pdm09-related pneumonia: an individual participant data meta-analysis.

PubMed

Muthuri, Stella G; Venkatesan, Sudhir; Myles, Puja R; Leonardi-Bee, Jo; Lim, Wei Shen; Al Mamun, Abdullah; Anovadiya, Ashish P; Araújo, Wildo N; Azziz-Baumgartner, Eduardo; Báez, Clarisa; Bantar, Carlos; Barhoush, Mazen M; Bassetti, Matteo; Beovic, Bojana; Bingisser, Roland; Bonmarin, Isabelle; Borja-Aburto, Victor H; Cao, Bin; Carratala, Jordi; Cuezzo, María R; Denholm, Justin T; Dominguez, Samuel R; Duarte, Pericles A D; Dubnov-Raz, Gal; Echavarria, Marcela; Fanella, Sergio; Fraser, James; Gao, Zhancheng; Gérardin, Patrick; Giannella, Maddalena; Gubbels, Sophie; Herberg, Jethro; Higuera Iglesias, Anjarath L; Hoeger, Peter H; Hoffmann, Matthias; Hu, Xiaoyun; Islam, Quazi T; Jiménez, Mirela F; Kandeel, Amr; Keijzers, Gerben; Khalili, Hossein; Khandaker, Gulam; Knight, Marian; Kusznierz, Gabriela; Kuzman, Ilija; Kwan, Arthur M C; Lahlou Amine, Idriss; Langenegger, Eduard; Lankarani, Kamran B; Leo, Yee-Sin; Linko, Rita; Liu, Pei; Madanat, Faris; Manabe, Toshie; Mayo-Montero, Elga; McGeer, Allison; Memish, Ziad A; Metan, Gokhan; Mikić, Dragan; Mohn, Kristin G I; Moradi, Ahmadreza; Nymadawa, Pagbajabyn; Ozbay, Bulent; Ozkan, Mehpare; Parekh, Dhruv; Paul, Mical; Poeppl, Wolfgang; Polack, Fernando P; Rath, Barbara A; Rodríguez, Alejandro H; Siqueira, Marilda M; Skręt-Magierło, Joanna; Talarek, Ewa; Tang, Julian W; Torres, Antoni; Törün, Selda H; Tran, Dat; Uyeki, Timothy M; van Zwol, Annelies; Vaudry, Wendy; Velyvyte, Daiva; Vidmar, Tjasa; Zarogoulidis, Paul; Nguyen-Van-Tam, Jonathan S

2016-05-01

The impact of neuraminidase inhibitors (NAIs) on influenza-related pneumonia (IRP) is not established. Our objective was to investigate the association between NAI treatment and IRP incidence and outcomes in patients hospitalised with A(H1N1)pdm09 virus infection. A worldwide meta-analysis of individual participant data from 20 634 hospitalised patients with laboratory-confirmed A(H1N1)pdm09 (n = 20 021) or clinically diagnosed (n = 613) 'pandemic influenza'. The primary outcome was radiologically confirmed IRP. Odds ratios (OR) were estimated using generalised linear mixed modelling, adjusting for NAI treatment propensity, antibiotics and corticosteroids. Of 20 634 included participants, 5978 (29·0%) had IRP; conversely, 3349 (16·2%) had confirmed the absence of radiographic pneumonia (the comparator). Early NAI treatment (within 2 days of symptom onset) versus no NAI was not significantly associated with IRP [adj. OR 0·83 (95% CI 0·64-1·06; P = 0·136)]. Among the 5978 patients with IRP, early NAI treatment versus none did not impact on mortality [adj. OR = 0·72 (0·44-1·17; P = 0·180)] or likelihood of requiring ventilatory support [adj. OR = 1·17 (0·71-1·92; P = 0·537)], but early treatment versus later significantly reduced mortality [adj. OR = 0·70 (0·55-0·88; P = 0·003)] and likelihood of requiring ventilatory support [adj. OR = 0·68 (0·54-0·85; P = 0·001)]. Early NAI treatment of patients hospitalised with A(H1N1)pdm09 virus infection versus no treatment did not reduce the likelihood of IRP. However, in patients who developed IRP, early NAI treatment versus later reduced the likelihood of mortality and needing ventilatory support. © 2015 The Authors. Influenza and Other Respiratory Viruses Published by John Wiley & Sons Ltd.

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.

Automated graphic assessment of respiratory activity is superior to pulse oximetry and visual assessment for the detection of early respiratory depression during therapeutic upper endoscopy.

PubMed

Vargo, John J; Zuccaro, Gregory; Dumot, John A; Conwell, Darwin L; Morrow, J Brad; Shay, Steven S

2002-06-01

Recommendations from the American Society of Anesthesiologists suggest that monitoring for apnea using the detection of exhaled carbon dioxide (capnography) is a useful adjunct in the assessment of ventilatory status of patients undergoing sedation and analgesia. There are no data on the utility of capnography in GI endoscopy, nor is the frequency of abnormal ventilatory activity during endoscopy known. The aims of this study were to determine the following: (1) the frequency of abnormal ventilatory activity during therapeutic upper endoscopy, (2) the sensitivity of observation and pulse oximetry in the detection of apnea or disordered respiration, and (3) whether capnography provides an improvement over accepted monitoring techniques. Forty-nine patients undergoing therapeutic upper endoscopy were monitored with standard methods including pulse oximetry, automated blood pressure measurement, and visual assessment. In addition, graphic assessment of respiratory activity with sidestream capnography was performed in all patients. Endoscopy personnel were blinded to capnography data. Episodes of apnea or disordered respiration detected by capnography were documented and compared with the occurrence of hypoxemia, hypercapnea, hypotension, and the recognition of abnormal respiratory activity by endoscopy personnel. Comparison of simultaneous respiratory rate measurements obtained by capnography and by auscultation with a pretracheal stethoscope verified that capnography was an excellent indicator of respiratory rate when compared with the reference standard (auscultation) (r = 0.967, p < 0.001). Fifty-four episodes of apnea or disordered respiration occurred in 28 patients (mean duration 70.8 seconds). Only 50% of apnea or disordered respiration episodes were eventually detected by pulse oximetry. None were detected by visual assessment (p < 0.0010). Apnea/disordered respiration occurs commonly during therapeutic upper endoscopy and frequently precedes the development of hypoxemia. Potentially important abnormalities in respiratory activity are undetected with pulse oximetry and visual assessment.

Time-series analysis of lung texture on bone-suppressed dynamic chest radiograph for the evaluation of pulmonary function: a preliminary study

NASA Astrophysics Data System (ADS)

Tanaka, Rie; Matsuda, Hiroaki; Sanada, Shigeru

2017-03-01

The density of lung tissue changes as demonstrated on imagery is dependent on the relative increases and decreases in the volume of air and lung vessels per unit volume of lung. Therefore, a time-series analysis of lung texture can be used to evaluate relative pulmonary function. This study was performed to assess a time-series analysis of lung texture on dynamic chest radiographs during respiration, and to demonstrate its usefulness in the diagnosis of pulmonary impairments. Sequential chest radiographs of 30 patients were obtained using a dynamic flat-panel detector (FPD; 100 kV, 0.2 mAs/pulse, 15 frames/s, SID = 2.0 m; Prototype, Konica Minolta). Imaging was performed during respiration, and 210 images were obtained over 14 seconds. Commercial bone suppression image-processing software (Clear Read Bone Suppression; Riverain Technologies, Miamisburg, Ohio, USA) was applied to the sequential chest radiographs to create corresponding bone suppression images. Average pixel values, standard deviation (SD), kurtosis, and skewness were calculated based on a density histogram analysis in lung regions. Regions of interest (ROIs) were manually located in the lungs, and the same ROIs were traced by the template matching technique during respiration. Average pixel value effectively differentiated regions with ventilatory defects and normal lung tissue. The average pixel values in normal areas changed dynamically in synchronization with the respiratory phase, whereas those in regions of ventilatory defects indicated reduced variations in pixel value. There were no significant differences between ventilatory defects and normal lung tissue in the other parameters. We confirmed that time-series analysis of lung texture was useful for the evaluation of pulmonary function in dynamic chest radiography during respiration. Pulmonary impairments were detected as reduced changes in pixel value. This technique is a simple, cost-effective diagnostic tool for the evaluation of regional pulmonary function.

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.

Autophagy and skeletal muscles in sepsis.

PubMed

Mofarrahi, Mahroo; Sigala, Ioanna; Guo, Yeting; Godin, Richard; Davis, Elaine C; Petrof, Basil; Sandri, Marco; Burelle, Yan; Hussain, Sabah N A

2012-01-01

Mitochondrial injury develops in skeletal muscles during the course of severe sepsis. Autophagy is a protein and organelle recycling pathway which functions to degrade or recycle unnecessary, redundant, or inefficient cellular components. No information is available regarding the degree of sepsis-induced mitochondrial injury and autophagy in the ventilatory and locomotor muscles. This study tests the hypotheses that the locomotor muscles are more prone to sepsis-induced mitochondrial injury, depressed biogenesis and autophagy induction compared with the ventilatory muscles. Adult male C57/Bl6 mice were injected with i.p. phosphate buffered saline (PBS) or E. coli lipopolysaccharide (LPS, 20 mg/kg) and sacrificed 24 h later. The tibialis anterior (TA), soleus (SOLD) and diaphragm (DIA) muscles were quickly excised and examined for mitochondrial morphological injury, Ca(++) retention capacity and biogenesis. Autophagy was detected with electron microscopy, lipidation of Lc3b proteins and by measuring gene expression of several autophagy-related genes. Electron microscopy revealed ultrastructural injuries in the mitochondria of each muscle, however, injuries were more severe in the TA and SOL muscles than they were in the DIA. Gene expressions of nuclear and mitochondrial DNA transcription factors and co-activators (indicators of biogenesis) were significantly depressed in all treated muscles, although to a greater extent in the TA and SOL muscles. Significant autophagosome formation, Lc3b protein lipidation and upregulation of autophagy-related proteins were detected to a greater extent in the TA and SOL muscles and less so in the DIA. Lipidation of Lc3b and the degree of induction of autophagy-related proteins were significantly blunted in mice expressing a muscle-specific IκBα superrepresor. We conclude that locomotor muscles are more prone to sepsis-induced mitochondrial injury, decreased biogenesis and increased autophagy compared with the ventilatory muscles and that autophagy in skeletal muscles during sepsis is regulated in part through the NFκB transcription factor.

Autophagy and Skeletal Muscles in Sepsis

PubMed Central

Mofarrahi, Mahroo; Sigala, Ioanna; Guo, Yeting; Godin, Richard; Davis, Elaine C.; Petrof, Basil; Sandri, Marco

2012-01-01

Background Mitochondrial injury develops in skeletal muscles during the course of severe sepsis. Autophagy is a protein and organelle recycling pathway which functions to degrade or recycle unnecessary, redundant, or inefficient cellular components. No information is available regarding the degree of sepsis-induced mitochondrial injury and autophagy in the ventilatory and locomotor muscles. This study tests the hypotheses that the locomotor muscles are more prone to sepsis-induced mitochondrial injury, depressed biogenesis and autophagy induction compared with the ventilatory muscles. Methodology/Principal Findings Adult male C57/Bl6 mice were injected with i.p. phosphate buffered saline (PBS) or E. coli lipopolysaccharide (LPS, 20 mg/kg) and sacrificed 24 h later. The tibialis anterior (TA), soleus (SOLD) and diaphragm (DIA) muscles were quickly excised and examined for mitochondrial morphological injury, Ca++ retention capacity and biogenesis. Autophagy was detected with electron microscopy, lipidation of Lc3b proteins and by measuring gene expression of several autophagy-related genes. Electron microscopy revealed ultrastructural injuries in the mitochondria of each muscle, however, injuries were more severe in the TA and SOL muscles than they were in the DIA. Gene expressions of nuclear and mitochondrial DNA transcription factors and co-activators (indicators of biogenesis) were significantly depressed in all treated muscles, although to a greater extent in the TA and SOL muscles. Significant autophagosome formation, Lc3b protein lipidation and upregulation of autophagy-related proteins were detected to a greater extent in the TA and SOL muscles and less so in the DIA. Lipidation of Lc3b and the degree of induction of autophagy-related proteins were significantly blunted in mice expressing a muscle-specific IκBα superrepresor. Conclusion/Significance We conclude that locomotor muscles are more prone to sepsis-induced mitochondrial injury, decreased biogenesis and increased autophagy compared with the ventilatory muscles and that autophagy in skeletal muscles during sepsis is regulated in part through the NFκB transcription factor. PMID:23056618

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

Optical imaging of the ventral medullary surface of developing kittens during ventilatory challenges.

PubMed

Gozal, D; Dong, X W; Rector, D M; Harper, R K; Harper, R M

1996-01-01

We used large-array optical recording procedures to examine maturation of regional neural activity within the ventral medullary surface (VMS) of anaesthetized kittens during graded hypercapnic and hypoxic challenges. The VMS was exposed through a ventral surgical approach in 10, 20, 30, and 45-day-old kittens and in adult cats under sodium pentobarbital anaesthesia. Arterial pressure, costal diaphragmatic EMG, and ECG were continuously monitored. A coherent image conduit with 12 mu fibre resolution was attached to a charge-coupled-device camera and positioned over the VMS. Reflected 660 nm light was digitized continuously at 2-s intervals during a baseline period, hyperoxic hypercapnia, (3, 5, and 10% CO2 in O2), and poikylocapnic hypoxia (6%, 9%, and 12% O2 in N2), and recovery. Sixty to seventy-five images within each epoch were averaged, and subtracted from baseline. Regional differences within the image were determined by ANOVA procedures (alpha = 0.05). During hypercapnia, an overall decrease in neural activity (increase in scattered light) occurred, which was marginally age-dependent. By 30 days, regional bidirectional reflectance changes in response to CO2 emerged in a small proportion of animals, and were similar to adult responses. Hypoxia induced a dose- and age-dependent decrease in overall scattered light. Transient "on" and "off" responses were common under both ventilatory stimuli. In 20-30-day kittens, marked rebound responses in reflectance accompanied cessation of hypoxic stimuli; such patterns were absent at other ages. At 30 days, a caudal-rostral bidirectionality in response to mild hypoxia (12% O2) began to emerge in a subset of animals. We conclude that dose-dependent response to ventilatory stimuli occur in the VMS at all post-natal ages of the kitten; however, in hypoxia, the magnitude of the overall reflectance changes is diminished relative to adult patterns. Rebound responses to hypoxia are present at particular ages, and older kittens begin to show a topographical organization of neural activation.

Effects of body position on the ventilatory response following an impulse exercise in humans.

PubMed

Haouzi, Philippe; Chenuel, Bruno; Chalon, Bernard

2002-04-01

The aim of this study was to identify some of the mechanisms that could be involved in blunted ventilatory response (VE) to exercise in the supine (S) position. The contribution of the recruitment of different muscle groups, the activity of the cardiac mechanoreceptors, the level of arterial baroreceptor stimulation, and the hemodynamic effects of gravity on the exercising muscles was analyzed during upright (U) and S exercise. Delayed rise in VE and pulmonary gas exchange following an impulselike change in work rate (supramaximal leg cycling at 240 W for 12 s) was measured in seven healthy subjects and six heart transplant patients both in U and S positions. This approach allows study of the relationship between the rise in VE and O2 uptake (VO2) without the confounding effects of contractions of different muscle groups. These responses were compared with those triggered by an impulselike change in work rate produced by the arms, which were positioned at the same level as the heart in S and U positions to separate effects of gravity on postexercising muscles from those on the rest of the body. Despite superimposable VO2 and CO2 output responses, the delayed VE response after leg exercise was significantly lower in the S posture than in the U position for each control subject and cardiac-transplant patient (-2.58 +/- 0.44 l and -3.52 +/- 1.11 l/min, respectively). In contrast, when impulse exercise was performed with the arms, reduction of ventilatory response in the S posture reached, at best, one-third of the deficit after leg exercise and was always associated with a reduction in VO2 of a similar magnitude. We concluded that reduction in VE response to exercise in the S position is independent of the types (groups) of muscles recruited and is not critically dependent on afferent signals originating from the heart but seems to rely on some of the effects of gravity on postexercising muscles.

AltitudeOmics: enhanced cerebrovascular reactivity and ventilatory response to CO2 with high-altitude acclimatization and reexposure.

PubMed

Fan, Jui-Lin; Subudhi, Andrew W; Evero, Oghenero; Bourdillon, Nicolas; Kayser, Bengt; Lovering, Andrew T; Roach, Robert C

2014-04-01

The present study is the first to examine the effect of high-altitude acclimatization and reexposure on the responses of cerebral blood flow and ventilation to CO2. We also compared the steady-state estimates of these parameters during acclimatization with the modified rebreathing method. We assessed changes in steady-state responses of middle cerebral artery velocity (MCAv), cerebrovascular conductance index (CVCi), and ventilation (V(E)) to varied levels of CO2 in 21 lowlanders (9 women; 21 ± 1 years of age) at sea level (SL), during initial exposure to 5,260 m (ALT1), after 16 days of acclimatization (ALT16), and upon reexposure to altitude following either 7 (POST7) or 21 days (POST21) at low altitude (1,525 m). In the nonacclimatized state (ALT1), MCAv and V(E) responses to CO2 were elevated compared with those at SL (by 79 ± 75% and 14.8 ± 12.3 l/min, respectively; P = 0.004 and P = 0.011). Acclimatization at ALT16 further elevated both MCAv and Ve responses to CO2 compared with ALT1 (by 89 ± 70% and 48.3 ± 32.0 l/min, respectively; P < 0.001). The acclimatization gained for V(E) responses to CO2 at ALT16 was retained by 38% upon reexposure to altitude at POST7 (P = 0.004 vs. ALT1), whereas no retention was observed for the MCAv responses (P > 0.05). We found good agreement between steady-state and modified rebreathing estimates of MCAv and V(E) responses to CO2 across all three time points (P < 0.001, pooled data). Regardless of the method of assessment, altitude acclimatization elevates both the cerebrovascular and ventilatory responsiveness to CO2. Our data further demonstrate that this enhanced ventilatory CO2 response is partly retained after 7 days at low altitude.

Adrenaline release evokes hyperpnoea and an increase in ventilatory CO2 sensitivity during hypoglycaemia: a role for the carotid body

PubMed Central

Thompson, Emma L.; Ray, Clare J.; Holmes, Andrew P.; Pye, Richard L.; Wyatt, Christopher N.; Kumar, Prem

2016-01-01

Key points Hypoglycaemia is counteracted by release of hormones and an increase in ventilation and CO2 sensitivity to restore blood glucose levels and prevent a fall in blood pH.The full counter‐regulatory response and an appropriate increase in ventilation is dependent on carotid body stimulation.We show that the hypoglycaemia‐induced increase in ventilation and CO2 sensitivity is abolished by preventing adrenaline release or blocking its receptors.Physiological levels of adrenaline mimicked the effect of hypoglycaemia on ventilation and CO2 sensitivity.These results suggest that adrenaline, rather than low glucose, is an adequate stimulus for the carotid body‐mediated changes in ventilation and CO2 sensitivity during hypoglycaemia to prevent a serious acidosis in poorly controlled diabetes. Abstract Hypoglycaemia in vivo induces a counter‐regulatory response that involves the release of hormones to restore blood glucose levels. Concomitantly, hypoglycaemia evokes a carotid body‐mediated hyperpnoea that maintains arterial CO2 levels and prevents respiratory acidosis in the face of increased metabolism. It is unclear whether the carotid body is directly stimulated by low glucose or by a counter‐regulatory hormone such as adrenaline. Minute ventilation was recorded during infusion of insulin‐induced hypoglycaemia (8–17 mIU kg−1 min−1) in Alfaxan‐anaesthetised male Wistar rats. Hypoglycaemia significantly augmented minute ventilation (123 ± 4 to 143 ± 7 ml min−1) and CO2 sensitivity (3.3 ± 0.3 to 4.4 ± 0.4 ml min−1 mmHg−1). These effects were abolished by either β‐adrenoreceptor blockade with propranolol or adrenalectomy. In this hypermetabolic, hypoglycaemic state, propranolol stimulated a rise in P aC O2, suggestive of a ventilation–metabolism mismatch. Infusion of adrenaline (1 μg kg−1 min−1) increased minute ventilation (145 ± 4 to 173 ± 5 ml min−1) without altering P aC O2 or pH and enhanced ventilatory CO2 sensitivity (3.4 ± 0.4 to 5.1 ± 0.8 ml min−1 mmHg−1). These effects were attenuated by either resection of the carotid sinus nerve or propranolol. Physiological concentrations of adrenaline increased the CO2 sensitivity of freshly dissociated carotid body type I cells in vitro. These findings suggest that adrenaline release can account for the ventilatory hyperpnoea observed during hypoglycaemia by an augmented carotid body and whole body ventilatory CO2 sensitivity. PMID:27027261

Adrenaline release evokes hyperpnoea and an increase in ventilatory CO2 sensitivity during hypoglycaemia: a role for the carotid body.

PubMed

Thompson, Emma L; Ray, Clare J; Holmes, Andrew P; Pye, Richard L; Wyatt, Christopher N; Coney, Andrew M; Kumar, Prem

2016-08-01

Hypoglycaemia is counteracted by release of hormones and an increase in ventilation and CO2 sensitivity to restore blood glucose levels and prevent a fall in blood pH. The full counter-regulatory response and an appropriate increase in ventilation is dependent on carotid body stimulation. We show that the hypoglycaemia-induced increase in ventilation and CO2 sensitivity is abolished by preventing adrenaline release or blocking its receptors. Physiological levels of adrenaline mimicked the effect of hypoglycaemia on ventilation and CO2 sensitivity. These results suggest that adrenaline, rather than low glucose, is an adequate stimulus for the carotid body-mediated changes in ventilation and CO2 sensitivity during hypoglycaemia to prevent a serious acidosis in poorly controlled diabetes. Hypoglycaemia in vivo induces a counter-regulatory response that involves the release of hormones to restore blood glucose levels. Concomitantly, hypoglycaemia evokes a carotid body-mediated hyperpnoea that maintains arterial CO2 levels and prevents respiratory acidosis in the face of increased metabolism. It is unclear whether the carotid body is directly stimulated by low glucose or by a counter-regulatory hormone such as adrenaline. Minute ventilation was recorded during infusion of insulin-induced hypoglycaemia (8-17 mIU kg(-1)  min(-1) ) in Alfaxan-anaesthetised male Wistar rats. Hypoglycaemia significantly augmented minute ventilation (123 ± 4 to 143 ± 7 ml min(-1) ) and CO2 sensitivity (3.3 ± 0.3 to 4.4 ± 0.4 ml min(-1)  mmHg(-1) ). These effects were abolished by either β-adrenoreceptor blockade with propranolol or adrenalectomy. In this hypermetabolic, hypoglycaemic state, propranolol stimulated a rise in P aC O2, suggestive of a ventilation-metabolism mismatch. Infusion of adrenaline (1 μg kg(-1)  min(-1) ) increased minute ventilation (145 ± 4 to 173 ± 5 ml min(-1) ) without altering P aC O2 or pH and enhanced ventilatory CO2 sensitivity (3.4 ± 0.4 to 5.1 ± 0.8 ml min(-1)  mmHg(-1) ). These effects were attenuated by either resection of the carotid sinus nerve or propranolol. Physiological concentrations of adrenaline increased the CO2 sensitivity of freshly dissociated carotid body type I cells in vitro. These findings suggest that adrenaline release can account for the ventilatory hyperpnoea observed during hypoglycaemia by an augmented carotid body and whole body ventilatory CO2 sensitivity. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

The effect of endurance training on the ventilatory response to exercise in elite cyclists.

PubMed

Hoogeveen, A R

2000-05-01

The purpose of this study was to investigate the effects of endurance training on the ventilatory response to acute incremental exercise in elite cyclists. Fifteen male elite cyclists [mean (SD) age 24.3 (3.3) years, height 179 (6) cm, body mass 71.1 (7.6) kg, maximal oxygen consumption (VO2max) 69 (7) ml x min(-1) x kg(-1)] underwent two exercise tests on a cycle ergometer. The first test was assessed in December, 6 weeks before the beginning of the cycling season. The second test was performed in June, in the middle of the season. During this period the subjects were expected to be in a highly endurance-trained state. The ventilatory response was assessed during an incremental exercise test (20 W x min(-1)). Oxygen consumption (VO2), carbon dioxide production (VCO2), minute ventilation (VE), and heart rate (HR) were assessed at the following points during the test: at workloads of 200 W, 250 W, 300 W, 350 W, 400 W and at the subject's maximal workload, at a respiratory exchange ratio (R) of 1, and at the ventilatory threshold (Th(vent)) determined using the V-slope-method. Post-training, the mean (SD) VO2max was increased from the pre-training level of 69 (7) ml x min(-1) x kg(-1) (range 61.4-78.6) to 78 (6) ml x min(-1) x kg(-1) (range 70.5-86.3). The mean post-training VO2 was significantly higher than the pre training value (P < 0.01) at all work rates, at Th(vent) and at R = 1. VO2 was also higher at all work rates except for 200 W and 250 W. VE was significantly higher at Th(vent) and R = 1. Training had no effect on HR at all workloads examined. An explanation for the higher VO2 cost for the same work rate may be that in the endurance-trained state, the adaptation to an exercise stimulus with higher intensity is faster than for the less-trained state. Another explanation may be that at the same work rate, in the less-endurance-trained state power is generated using a significantly higher anaerobic input. The results of this study suggest the following practical recommendations for training management in elite cyclists: (1) the VO2 for a subject at the same work rate may be an indicator of the endurance-trained state (i.e., the higher the VO2, the higher the endurance-trained capacity), and (2) the need for multiple exercise tests for determining the HR at Th(vent) during a cycling season is doubtful since at Th(vent) this parameter does not differ much following endurance training.

Automated respiratory cycles selection is highly specific and improves respiratory mechanics analysis.

PubMed

Rigo, Vincent; Graas, Estelle; Rigo, Jacques

2012-07-01

Selected optimal respiratory cycles should allow calculation of respiratory mechanic parameters focusing on patient-ventilator interaction. New computer software automatically selecting optimal breaths and respiratory mechanics derived from those cycles are evaluated. Retrospective study. University level III neonatal intensive care unit. Ten mins synchronized intermittent mandatory ventilation and assist/control ventilation recordings from ten newborns. The ventilator provided respiratory mechanic data (ventilator respiratory cycles) every 10 secs. Pressure, flow, and volume waves and pressure-volume, pressure-flow, and volume-flow loops were reconstructed from continuous pressure-volume recordings. Visual assessment determined assisted leak-free optimal respiratory cycles (selected respiratory cycles). New software graded the quality of cycles (automated respiratory cycles). Respiratory mechanic values were derived from both sets of optimal cycles. We evaluated quality selection and compared mean values and their variability according to ventilatory mode and respiratory mechanic provenance. To assess discriminating power, all 45 "t" values obtained from interpatient comparisons were compared for each respiratory mechanic parameter. A total of 11,724 breaths are evaluated. Automated respiratory cycle/selected respiratory cycle selections agreement is high: 88% of maximal κ with linear weighting. Specificity and positive predictive values are 0.98 and 0.96, respectively. Averaged values are similar between automated respiratory cycle and ventilator respiratory cycle. C20/C alone is markedly decreased in automated respiratory cycle (1.27 ± 0.37 vs. 1.81 ± 0.67). Tidal volume apparent similarity disappears in assist/control: automated respiratory cycle tidal volume (4.8 ± 1.0 mL/kg) is significantly lower than for ventilator respiratory cycle (5.6 ± 1.8 mL/kg). Coefficients of variation decrease for all automated respiratory cycle parameters in all infants. "t" values from ventilator respiratory cycle data are two to three times higher than ventilator respiratory cycles. Automated selection is highly specific. Automated respiratory cycle reflects most the interaction of both ventilator and patient. Improving discriminating power of ventilator monitoring will likely help in assessing disease status and following trends. Averaged parameters derived from automated respiratory cycles are more precise and could be displayed by ventilators to improve real-time fine tuning of ventilator settings.

Injection sclerotherapy for haemorrhoids causing adult respiratory distress syndrome.

PubMed

Rashid, Muhammad Misbah; Murtaza, Badar; Gondal, Zafar Iqbal; Mehmood, Arshad; Shah, Shahzad Saleem; Abbasi, Muhammad Hanif; Tamimy, Muhammad Sarmad; Kazmi, Syed Tahawwar Mujtaba

2006-05-01

A young lady with first-degree haemorrhoids was administered injection sclerotherapy with 5% phenol in almond oil. Soon after the injection, she developed syncope and later signs and symptoms of acute respiratory distress syndrome (ARDS). She was kept on ventilatory support for 4 days, made a smooth recovery and was successfully weaned off from the ventilator.

[Aerogenic risk factors and diagnosis of bauxite pneumoconiosis].

PubMed

Peshkova, A O; Roslaia, N A; Roslyĭ, O F; Likhacheva, E I; Fedoruk, A A; Slyshkina, T V; Vagina, E R

2013-01-01

The research purpose is an estimation of influence of the bauxite dust on the state of the bronchopulmonary system of workers. It has been indicated that exposure of the poor fibrogenic dust while the process of the bauxite ore extraction, results in development of pnevmokoniosis characterized by substantial ventilatory and haemodynamic disorders limiting the workability of patients.

Effects of Pregnancy on Responses to Exercise Above and Below the Ventilatory Anaerobic THreshold

DTIC Science & Technology

1999-10-01

815-827, 1998. Chapers in Books Wolfe, L.A. and M.F. Mottola. Chapter on Pregnacy In: (D. Kumbhare and J.V Basmajian, Eds.). Clinical Decision Makinq...effects of All and AVP may be more easily identified in early pregnacy when progesterone levels are relatively low. Further study is recommended to

Annual Progress Report, Fiscal Year 1980

DTIC Science & Technology

1980-10-01

Stress Rating Scales Heat Stroke Respiratory Control Hepatic Necrosis Survey Analysis Load Carriage Sustained/Continuous Operations Human Performances...wire placed percutaneously into one of the external jugular veins, under local anesthesia. Ventilatory measurements were made with the goat wearing a...electrical apparatus that produces positive air ions or in closed artificial environments which deplete negative air ions. Local positive ionization may

Life-Threatening Opioid Toxicity

DTIC Science & Technology

1987-01-01

mu recep- Fentanyl (Sublimaze) tor has been determined to mediate analgesia Propoxyphene (Darvon) and ventilatory depre.;sion. Furthermore, it Pure...following opioid overdose . The reduction in ventilation is accompanied by Opioids produce their major effect on the a decreased chemosensitivity to...opiates a o d F Diphenoxylate (active ingredient in Lomotil)a mperidline overdose . Fuithermore, ven- rpxhe (avnmepedinePropoxyphene Darvon) titatory

Lowland copperhead (Austrelaps superbus) envenomation causing severe neuromuscular paralysis in a dog.

PubMed

Wright, L V; Indrawirawan, Y H

2017-06-01

A case of lowland copperhead snake (Austrelaps superbus) envenomation in a dog is described. The dog developed severe and prolonged neuromuscular paralysis, including ventilatory failure. The dog was treated successfully with antivenom, intravenous fluids and mechanical ventilation. The toxic components of lowland copperhead snake venom are reviewed. © 2017 Australian Veterinary Association.

CO[subscript 2] Rebreathing: An Undergraduate Laboratory to Study the Chemical Control of Breathing

ERIC Educational Resources Information Center

Domnik, N. J.; Turcotte, S. E.; Yuen, N. Y.; Iscoe, S.; Fisher, J. T.

2013-01-01

The Read CO[subscript]2 rebreathing method (Read DJ. "A clinical method for assessing the ventilatory response to carbon dioxide." "Australas Ann Med" 16: 20-32, 1967) provides a simple and reproducible approach for studying the chemical control of breathing. It has been widely used since the modifications made by Duffin and…

The Effect of Physiotherapy on Ventilatory Dependency and the Length of Stay in an Intensive Care Unit

ERIC Educational Resources Information Center

Malkoc, Mehtap; Karadibak, Didem; Yldrm, Yucel

2009-01-01

The aim of this study was to assess the effect of physiotherapy on ventilator dependency and lengths of intensive care unit (ICU) stay. Patients were divided into two groups. The control group, which received standard nursing care, was a retrospective chart review. The data of control patients who were not receiving physiotherapy were obtained…

[Aggressive fibromatosis of the nasal sinuses].

PubMed

Artazkoz del Toro, J J; Pons Rocher, F; Dalmau Galofré, J; Mompó Romero, L; Guallart Domènech, F; Serrano Badía, E

1994-01-01

A case report of a feminine patient who complained of nasal ventilatory obstruction and nasosinusal polyposis is presented. She underwent surgery and the pathological study revealed the existence of an aggressive fibromatosis. The AA. review the literature dealing with this illness and explain an update state of the clinical features, treatment and the course of this rare entity, closely related to fibrosarcoma.

Annual Progress Report, FY 1980, 1 October 1979 - 30 September 1980,

DTIC Science & Technology

1980-10-01

coordinating an integrated pest management program, and constructing initial pilot prototypes, test models, and pro- ducing limited quantities of medical...Screening Test Based on the Ventilatory Responses of Fish . . . . . . . a & a . . . . 25 Chemistry and Molecular Biology of the Disinfection Process...Sink Unit, Surgical, Field (NSN 6545-00-935-4056), Engineering Evaluation of . . . . . . . . . . . . . . . . . . 69 Technical Feasibility Testing (TFT

Initial indication of treatment in 60 patients with sleep obstructive ventilatory disturbance.

PubMed

de Tarso Moura Borges, Paulo; Paschoal, Jorge Rizzato

2005-01-01

The author present a retrospective descriptive study of 60 patients with sleep obstructive ventilatory disturbance who have taken medical advice at the Centro Campinas de Otorrinolaringologia e Cirurgia de Cabeça e Pescoço during a period of three years. All the patients have been examined after standardized protocol and decisions related to the treatment have been taken after systematic multidisciplinary discussion. clinical retrospective. The patients were distributed into two groups according to the proposal of surgical and non-surgical treatment. After so, they were studied according to the model of treatment proposed and the main propaedeutic findings: respiratory disturbance index (RDI), body mass index (BMI), cephalometric analysis and Müller maneuver. The main features were compared--isolated or in association--with the model of treatment proposed. Amongst several conclusions obtained, the most important were: surgical and non-surgical treatment were indicated almost in the same proportion for of snoring; surgical treatments were most indicated for snoring and Apnoea-Hipopnoea Syndrome, despite of its modality; RDI, BMI and cephalometric analysis and Müller maneuver had no influence at any therapeutic modality; the therapeutic decision was taken after standardized protocol and systematic multidisciplinary discussion, where each case was discussed individually.

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.

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.

[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.

Implications of air pollution effects on athletic performance

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

Pierson, W.E.; Covert, D.S.; Koenig, J.Q.

Both controlled human studies and observational studies suggest that air pollution adversely affects athletic performance during both training and competition. The air pollution dosage during exercise is much higher than during rest because of a higher ventilatory rate and both nasal and oral breathing in the former case. For example, sulfur dioxide, which is a highly water-soluble gas, is almost entirely absorbed in the upper respiratory tract during nasal breathing. However, with oral pharyngeal breathing, the amount of sulfur dioxide that is absorbed is significantly less, and with exercise and oral pharyngeal breathing a significant decrease in upper airway absorptionmore » occurs, resulting in a significantly larger dosage of this pollutant being delivered to the tracheobronchial tree. Recently, several controlled human studies have shown that the combination of exercise and pollutant exposure (SO/sub 2/ or O/sub 3/) caused a marked bronchoconstriction and reduced ventilatory flow when compared to pollution exposure at rest. In a situation like the Olympic Games where milliseconds and millimeters often determine the success of athletes, air pollution can be an important factor in affecting their performance. This paper examines possible impacts of air pollution on athletic competition.« less

Intermittent hypoxia, respiratory plasticity and sleep apnea in humans: present knowledge and future investigations.

PubMed

Mateika, Jason H; Syed, Ziauddin

2013-09-15

This review examines the role that respiratory plasticity has in the maintenance of breathing stability during sleep in individuals with sleep apnea. The initial portion of the review considers the manner in which repetitive breathing events may be initiated in individuals with sleep apnea. Thereafter, the role that two forms of respiratory plasticity, progressive augmentation of the hypoxic ventilatory response and long-term facilitation of upper airway and respiratory muscle activity, might have in modifying breathing events in humans is examined. In this context, present knowledge regarding the initiation of respiratory plasticity in humans during wakefulness and sleep is addressed. Also, published findings which reveal that exposure to intermittent hypoxia promotes breathing instability, at least in part, because of progressive augmentation of the hypoxic ventilatory response and the absence of long-term facilitation, are considered. Next, future directions are presented and are focused on the manner in which forms of plasticity that stabilize breathing might be promoted while diminishing destabilizing forms, concurrently. These future directions will consider the potential role of circadian rhythms in the promotion of respiratory plasticity and the role of respiratory plasticity in enhancing established treatments for sleep apnea. Published by Elsevier B.V.

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

Effects of underwater bubble CPAP on very-low-birth-weight preterm newborns in the delivery room and after transport to the neonatal intensive care unit.

PubMed

Abelenda, Vera Lucia Barros; Valente, Tania Cristina Oliveira; Marinho, Cirlene Lima; Lopes, Agnaldo José

2018-01-01

The development of less invasive ventilatory strategies in very-low-birth-weight (VLBW) preterm newborns has been a growing concern in recent decades. This study aimed to measure differences in the clinical progression of preterm newborns using two distinct periods in a university hospital: before and after using underwater bubble continuous positive airway pressure (ubCPAP). This is a retrospective study of VLBW preterm newborns with gestational ages less than or equal to 32 weeks admitted to the neonatal intensive care unit. The time series was divided into two groups: a pre-CPAP group ( n = 45) and a post-CPAP group ( n = 40). The post-CPAP group had fewer resuscitations, required fewer surfactant doses, spent fewer days on mechanical ventilation, and demonstrated less of a need for fraction of inspired oxygen > 30%. UbCPAP is an easy to use, minimally invasive, and effective ventilatory strategy for VLBW preterm newborns that can be used in environments with limited resources. Thus, adopting this simple strategy as part of a service organization and health policy can positively impact outcomes.

Hypercapnic encephalopathy syndrome: a new frontier for non-invasive ventilation?

PubMed

Scala, Raffaele

2011-08-01

According to the classical international guidelines, non-invasive ventilation is contraindicated in hypercapnic encephalopathy syndrome (HES) due to the poor compliance to ventilatory treatment of confused/agitated patients and the risk of aspirative pneumonia related to lack of airways protection. As a matter of fact, conventional mechanical ventilation has been recommended as "golden standard" in these patients. However, up to now there are not controlled data that have demonstrated in HES the advantage of conventional mechanical ventilation vs non-invasive ventilation. In fact, patients with altered mental status have been systematically excluded from the randomised and controlled trials performed with non-invasive ventilation in hypercapnic acute respiratory failure. Recent studies have clearly demonstrated that an initial cautious NPPV trial in selected HES patients may be attempt as long as there are no other contraindications and the technique is provided by experienced caregivers in a closely monitored setting where ETI is always readily available. The purpose of this review is to report the physiologic rationale, the clinical feasibility and the still open questions about the careful use of non-invasive ventilation in HES as first-line ventilatory strategy in place of conventional mechanical ventilation via endotracheal intubation. Copyright © 2011 Elsevier Ltd. All rights reserved.

[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.

Neurodevelopmental Outcomes of Extremely Low Birth Weight Infants Ventilated With Continuous Positive Airway Pressure vs. Mechanical Ventilation

PubMed Central

Thomas, Cameron W.; Meinzen-Derr, Jareen; Hoath, Steven B.; Narendran, Vivek

2012-01-01

OBJECTIVE To compare continuous positive airway pressure (CPAP) vs. traditional mechanical ventilation (MV) at 24 h of age as predictors of neurodevelopmental (ND) outcomes in extremely low birth weight (ELBW) infants at 18-22 mo corrected gestational age (CGA). METHODS Infants ≤ 1000g birth weight born from January 2000 through December 2006 at two hospitals at the Cincinnati site of the National Institute of Child Health and Human Development Neonatal Research Network were evaluated comparing CPAP (N = 198) vs. MV (N = 109). Primary outcomes included the Bayley Score of Infant Development Version II (BSID-II), presence of deafness, blindness, cerebral palsy, bronchopulmonary dysplasia and death. RESULTS Ventilatory groups were similar in gender, rates of preterm prolonged rupture of membranes, antepartum hemorrhage, use of antenatal antibiotics, steroids, and tocolytics. Infants receiving CPAP weighed more, were older, were more likely to be non-Caucasian and from a singleton pregnancy. Infants receiving CPAP had better BSID-II scores, and lower rates of BPD and death. CONCLUSIONS After adjusting for acuity differences, ventilatory strategy at 24 h of age independently predicts long-term neurodevelopmental outcome in ELBW infants. PMID:21853318

The relationship of placement accuracy and insertion times for the laryngeal mask airway to the training of inexperienced dental students.

PubMed

Morse, Zac; Sano, Kimito; Kageyama, Ikuo; Kanri, Tomio

2002-01-01

Any health care professional can be faced with a medical emergency in which the patient needs ventilatory support. Bag-valve-mask ventilation with the assistance of an oropharyngeal airway that uses 100% oxygen is currently the preferred method for artificial ventilation. This procedure is generally performed ineffectively by most dentists inexperienced in airway management. We examined whether a short and simple period of training by dental students inexperienced in airway management would increase the speed and accuracy of the placement of the laryngeal mask airway (LMA), which may be a superior airway device to the bag-valve-mask and oropharyngeal airway. Thirty-five dental students inexperienced in airway management were divided into 3 groups. The first group received only a demonstration on how to use the LMA. The second and third groups received the demonstration plus practiced inserting the LMA 5 and 10 times, respectively. A dental anesthesiologist graded the placement of the LMA with a tracheobroncho-fiberscope (fiberoptic bronchoscope). Those who practiced inserting the LMA 5 times faired better than those who received no training; however, those who practiced 10 times did not do any better than the second group. The LMA can be inserted rapidly and effectively by dentists inexperienced in airway management after a short period of simple training that may be critical when personnel experienced in intubation are not readily available.

Impact of maternal obesity on very preterm infants.

PubMed

Khalak, Rubia; Rijhsinghani, Asha; McCallum, Sarah E

2017-05-01

Infants born at less than  34 weeks' gestational age are at higher risk for morbidity and mortality. Data are limited on the impact of maternal obesity on the very preterm infant. This study reviewed whether maternal obesity further increases the intensive care needs of very preterm infants of less than 34 weeks' gestation. Maternal and neonatal data for live-born singleton births of 23 0/7 to 33 6/7 weeks' gestation delivering in upstate New York were reviewed. BMI categorization followed the National Institutes of Health BMI classification that subdivides obesity into three ascending BMI groups. Records were obtained on 1,224 women, of whom 31.6% were classified with obesity. Despite similar mean gestational age (31 to 31.6 weeks, P = 0.57) and birth weight (1,488 to 1,569 g, P = 0.51) of the infants in the BMI categories, delivery room (DR) resuscitation was more common for infants of women with level III obesity (63.2%, P = 0.04) with a trend toward the continued need for assisted ventilation (54.7%, P = 0.06). Preterm infants of women with level III obesity were more likely to require DR resuscitation with a trend to continued need for ventilatory support beyond 6 hours of age. This could impact utilization of DR resources at delivering hospitals. © 2017 The Obesity Society.

Effects of Thermal Status on Markers of Blood Coagulation During Simulated Hemorrhage

DTIC Science & Technology

2016-04-01

consumption would further reduce LBNP tolerance in the presence of moderate skin temperatures (35°C). Against our expectations, LBNP tolerance was not...exerted an effect sufficient in magnitude to mask any further impairments induced by additional dehydration and increases in body temperature ...Ventilatory parameters ( ventilation , tidal volume and breathing rate) were measured (body temperature and pressure saturated) using an automated gas

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

Intermittent hypercapnia induces long-lasting ventilatory plasticity to enhance CO2 responsiveness to overcome dysfunction

NASA Astrophysics Data System (ADS)

Mosher, Bryan Patrick

The ability of the brain to detect (central CO2 chemosensitivity) and respond to (central CO2 chemoresponsiveness) changes in tissue CO2/pH, is a homeostatic process essential for mammalian life. Dysfunction of the serotonin (5-HT) mechanisms compromises ventilatory CO 2 chemosensitivity/responsiveness and may enhance vulnerability to pathologies such as the Sudden Infant Death Syndrome (SIDS). The laboratory of Dr. Michael Harris has shown medullary raphe contributions to central chemosensitivity involving both 5-HT- and gamma-aminobutyric acid (GABA)-mediated mechanisms. I tested the hypothesis that postnatal exposure to mild intermittent hypercapnia (IHc) induces respiratory plasticity, due in part to strengthening of bicuculline- and saclofen-sensitive mechanisms (GABAA and GABAB receptor antagonists respectively). Rats were exposed to IHc-pretreatment (8 cycles of 5 % CO2) for 5 days beginning at postnatal day 12 (P12). I subsequently assessed CO2 responsiveness using an in situ perfused brainstem preparation. Hypercapnic responses were determined with and without pharmacological manipulation. In addition, IHc-pretreatment effectiveness was tested for its ability to overcome dysfunction in the CO2 responsiveness induced by a dietary tryptophan restriction. This dysfunctional CO2 responsiveness has been suggested to arise from a chronic, partial 5-HT reduction imparted by the dietary restriction. Results show IHc-pretreatment induced plasticity sufficient for CO2 responsiveness despite removal of otherwise critical ketanserin-sensitive mechanisms. CO2 responsiveness following IHc-pretreatment was absent if ketanserin was combined with bicuculline and saclofen, indicating that the plasticity was dependent upon bicuculline- and saclofen-sensitive mechanisms. IHc--induced plasticity was also capable of overcoming the ventilatory defects associated with maternal dietary restriction. Duration of IHc-induced plasticity was also investigated and found to last far into life (up to P65). Furthermore, I performed experiments to investigate if IHc-induced plasticity was more robust at a specific developmental period. No such critical period was identified as IHc-pretreatment induced robust respiratory plasticity when administered at all developmental periods tested (P12-16, P21-25 and P36-0). I propose that IHc-induced plasticity may be able to reduce the severity of reflex dysfunctions underlying pathologies such as SIDS.

Ventilatory function in rubber processing workers: acute changes over the workshift.

PubMed Central

Governa, M; Comai, M; Valentino, M; Antonicelli, L; Rinaldi, F; Pisani, E

1987-01-01

When considering rubber tyre manufacturing from an occupational health viewpoint, three areas may be identified in which exposure to respirable materials are potentially harmful: the processing, curing, and talc areas. A study of the ventilatory function of the entire work force employed in the processing area in a rubber tyre manufacturing plant was undertaken to determine whether an acute reduction in lung function occurs over the course of their working shift (the plant worked a three shift system) and whether a chronic exposure to the occupational airborne contaminants causes permanent changes in lung function. The ventilatory function was measured at the worksite at the beginning and immediately after the end of the workshift. No evidence of chronic obstructive pulmonary disease was found and in most cases no significant decline in FEV1 was observed. Only one of the 79 individuals showed a moderate obstruction, measured by the ratio FEV1/FVC which gave the value of 0.55, with no variation over the shift. For non-smokers, the FVC, FEV1, and FEF25-75% were lower in those exposed for more than five years than in those exposed for five years or less. A similar pattern was also observed in the FVC and FEV1 of the smokers. None of these differences was statistically significant. Within each exposure group the pulmonary function of the smokers was lower than that of the non-smokers, but the only significant difference was found in the values of FEF25-75%. Only one man showed a decline in the FEV1/FVC ratio over the shift, but during each shift, a decrease in all the lung function tests was observed. The decrease was smallest during the first of the three shifts. These results are thought to support the hypothesis that there are acute adverse effects over an eight hour shift. Further investigations are needed to discover whether these acute changes in lung function result from a chemical stimulation or irritant receptors in the airways. PMID:3814549

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.