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1

Pulmonary ventilation and perfusion abnormalities and ventilation perfusion imbalance in children with pulmonary atresia or extreme tetralogy of Fallot  

SciTech Connect

Xenon-133 lung ventilation and perfusion scans were done preoperatively after cardiac catheterization and cineangiocardiography in 19 children; 6 had pulmonary atresia with an intact ventricular septum and hypoplastic right ventricle, 4 pulmonary atresia with associated complex univentricular heart, and 9 extreme Tetralogy of Fallot. The four patients with discrepancies in the sizes of the left and right pulmonary arteries on angiography had marked asymmetry of pulmonary perfusion and ventilation-perfusion imbalance on scintigraphy. Similar degrees of asymmetry and imbalance were present in 6 of the 15 children with equal-size pulmonary vessels. Asymmetry of pulmonary perfusion and ventilation-perfusion imbalance were associated with a poor prognosis.

Dowdle, S.C.; Human, D.G.; Mann, M.D. (Univ. of Cape Town (South Africa))

1990-08-01

2

Pulmonary ventilation/perfusion scan  

MedlinePLUS

V/Q scan; Ventilation/perfusion scan; Lung ventilation/perfusion scan ... A pulmonary ventilation/perfusion scan is actually two tests. They may be done separately or together. During the perfusion ...

3

Reverse ventilation--perfusion mismatch  

SciTech Connect

Patients having lobar airway obstruction or consolidation usually have decreases of both ventilation and perfusion on lung scans. We report three patients in whom hypoxic vasoconstriction was apparently incomplete, resulting in a ''reversed'' ventilation-perfusion mismatch. Perfusion of the hypoxic lobe on the radionuclide scan was associated with metabolic alkalosis, pulmonary venous and pulmonary arterial hypertension in these patients.

Palmaz, J.C.; Barnett, C.A.; Reich, S.B.; Krumpe, P.E.; Farrer, P.A.

1984-01-01

4

Ventilation-perfusion imaging in pulmonary papillomatosis  

SciTech Connect

Three children with laryngeal papillomas involving the lungs had serial ventilation-perfusion scintigrams to assess results of therapy designed to reduce the bronchial involvement. Different imaging patterns were observed depending on size, number, and location of lesions. In early parenchymal involvement a ventilation-perfusion mismatch was seen. The initial and follow-up studies correlated well with clinical and radiographic findings. This noninvasive procedure is helpful in evaluating ventilatory and perfusion impairment in these patients as well as their response to treatment.

Espinola, D.; Rupani, H.; Camargo, E.E.; Wagner, H.N. Jr.

1981-11-01

5

Inert gas analysis of ventilation-perfusion matching during hemodialysis.  

PubMed Central

The mechanism of hypoxemia during hemodialysis was investigated by the multiple inert gas elimination technique in anesthetized, paralyzed, mechanically ventilated dogs. Profound leukopenia occurred in the first hour of a 2-h hemodialysis with a cuprophan membrane and dialysate that contained acetate. Arterial partial pressure of O2 and CO2 and oxygen consumption remained unchanged during dialysis. Pulmonary carbon dioxide elimination and lung respiratory exchange ratio decreased with the initiation of dialysis, remained depressed throughout the duration of dialysis, and returned to predialysis levels after the cessation of dialysis. Cardiac output diminished during dialysis but did not return to base-line levels after dialysis. Multiple indices calculated from inert gas analysis revealed no ventilation-perfusion mismatching during dialysis. The shunt and perfusion to regions of low alveolar ventilation-to-perfusion ratio (VA/Q) were unchanged during dialysis. There was no change in the mean or standard deviation of the profile of the percentage of total perfusion to regions of the lung that had VA/Q near 1.0; nor was there any increase in the directly calculated arterial-alveolar partial pressure differences for the inert gases during dialysis. Dead space became mildly elevated during dialysis. These results show that during dialysis with controlled ventilation there is no ventilation-perfusion mismatching that leads to hypoxemia. During spontaneous ventilation any hypoxemia must occur due to hypoventilation secondary to the CO2 exchange by the dialyzer and subsequent reduction in pulmonary CO2 exchange.

Ralph, D D; Ott, S M; Sherrard, D J; Hlastala, M P

1984-01-01

6

Combined MR Proton Lung Perfusion/Angiography and Helium Ventilation  

PubMed Central

Three-dimensional (3D) perfusion imaging allows the assessment of pulmonary blood flow in parenchyma and main pulmonary arteries simultaneously. MRI using laser-polarized 3He gas clearly shows the ventilation distribution with high signal-to-noise ratio (SNR). In this report, the feasibility of combined lung MR angiography, perfusion, and ventilation imaging is demonstrated in a porcine model. Ultrafast gradient-echo sequences have been used for 3D perfusion and angiographic imaging, in conjunction with the use of contrast agent injections. 2D multiple-section 3He imaging was performed subsequently by inhalation of 450 ml of hyperpolarized 3He gas. The MR techniques were examined in a series of porcine models with externally delivered pulmonary emboli and/or airway occlusions. With emboli, perfusion deficits without ventilation defects were observed; airway occlusion resulted in matched deficits in perfusion and ventilation. High-resolution MR angiography can unambiguously reveal the location and size of the blood emboli. The combination of the three imaging methods may provide complementary information on abnormal lung anatomy and function.

Zheng, Jie; Leawoods, Jason C.; Nolte, Mark; Yablonskiy, Dmitriy A.; Woodard, Pamela K.; Laub, Gerhardt; Gropler, Robert J.; Conradi, Mark S.

2007-01-01

7

Teaching Ventilation/Perfusion Relationships in the Lung  

ERIC Educational Resources Information Center

|This brief review is meant to serve as a refresher for faculty teaching respiratory physiology to medical students. The concepts of ventilation and perfusion matching are some of the most challenging ideas to learn and teach. Some strategies to consider in teaching these concepts are, first, to build from simple to more complex by starting with a…

Glenny, Robb W.

2008-01-01

8

Ventilation and perfusion magnetic resonance imaging of the lung  

PubMed Central

Summary A close interaction between the respiratory pump, pulmonary parenchyma and blood circulation is essential for a normal lung function. Many pulmonary diseases present, especially in their initial phase, a variable regional impairment of ventilation and perfusion. In the last decades various techniques have been established to measure the lung function. Besides the global pulmonary function tests (PFTs) imaging techniques gained increasing importance to detect local variations in lung function, especially for ventilation and perfusion assessment. Imaging modalities allow for a deeper regional insight into pathophysiological processes and enable improved planning of invasive procedures. In contrast to computed tomography (CT) and the nuclear medicine techniques, magnetic resonance imaging (MRI), as a radiation free imaging modality gained increasing importance since the early 1990 for the assessment of pulmonary function. The major inherent problems of lung tissue, namely the low proton density and the pulmonary and cardiac motion, were overcome in the last years by a constant progress in MR technology. Some MR techniques are still under development, a process which is driven by scientific questions regarding the physiology and pathophysiology of pulmonary diseases, as well as by the need for fast and robust clinically applicable imaging techniques as safe therapy monitoring tools. MRI can be considered a promising ionizing-free alternative to techniques like CT or nuclear medicine techniques for the evaluation of lung function. The goal of this article is to provide an overview on selected MRI techniques for the assessment of pulmonary ventilation and perfusion.

Bauman, Grzegorz; Eichinger, Monika

2012-01-01

9

Ventilation-perfusion studies and the diagnosis of pulmonary embolism: concise communication  

SciTech Connect

Various diagnostic strategies for the assessment of pulmonary embolism were developed using the results of scintigraphic examinations in 169 patients who had both scintigraphic studies and pulmonary angiography. Likelihood ratios for several perfusion and ventilation-perfusion patterns were first obtained, and Bayes' Theorem was then applied using a range of prior probabilities for pulmonary embolism. Resulting posterior probabilities ranged from under 10% to over 90%. The former values held for patients with small perfusion defects and no ventilation study, regardless of their prior probabilities for pulmonary embolism. The latter values held for patients with average to high prior probabilities and ventilation-perfusion mismatches.

McNeil, B.J.

1980-04-01

10

Quantitative ventilation-perfusion lung scans in infants and children: utility of a submicronic radiolabeled aerosol to assess ventilation  

SciTech Connect

The quantitative assessment of regional pulmonary ventilation and perfusion provides useful information regarding lung function. Its use in infants and young children, however, has been minimal because of practical and technical limitations when the distribution of ventilation is assessed by radioactive gases. In 16 infants and children we used an inexpensive commercially available nebulizer to produce a submicronic aerosol labeled with 99mtechnetium-diethylenetriamine pentacetic acid to assess ventilation quantitatively, and intravenous injections of 99mtechnetium-labeled macroaggregates of albumin to assess pulmonary perfusion quantitatively. Studies were safely completed in both ambulatory and critically ill patients, including two premature infants who had endotracheal tubes in place for ventilatory support. No sedation or patient cooperation is required. This technique enables any department of nuclear medicine to measure regional pulmonary ventilation and perfusion in infants and children.

O'Brodovich, H.M.; Coates, G.

1984-09-01

11

The effect of omalizumab on ventilation and perfusion in adults with allergic asthma  

PubMed Central

Omalizumab promotes clinical improvement in patients with allergic asthma, but its effect on pulmonary function is unclear. One possibility is that omalizumab improves asthma symptoms through effects on the regional distributions of ventilation, perfusion, and ventilation/perfusion matching, metrics which can be assessed with Nitrogen-13-saline Position Emission Tomography (PET). Four adults with moderate to severe uncontrolled allergic asthma underwent symptom assessment, spirometry and functional pulmonary imaging with Nitrogen-13-saline PET before and after 4-5 months of treatment with omalizumab. PET imaging was used to determine ventilation/perfusion ratios, the heterogeneity (coefficient of variation, COV) of ventilation and perfusion, and lung regions with ventilation defects. There were no significant changes in spirometry values after omalizumab treatment, but there was a trend towards an improvement in symptom scores. There was little change in the matching of ventilation and perfusion. The COV of perfusion was similar before and after omalizumab treatment. The COV of ventilation was also similar before (0.57 (0.28)) and after (0.66 (0.13)) treatment, and it was similar to previously published values for healthy subjects. There was a non-significant trend towards an increase in the extent of ventilation defects after omalizumab treatment, from 5 (15)% to 12.8 (14.7)%. Treatment of moderate to severe uncontrolled allergic asthma with omalizumab did not result in a significant improvement in ventilation and perfusion metrics assessed with functional PET imaging. The normal COV of ventilation which was unaffected by treatment supports the hypothesis that omalizumab exerts its clinical effect on lung function during allergen exposure rather than in between exacerbations.

Kelmenson, Daniel A; Kelly, Vanessa J; Winkler, Tilo; Kone, Mamary T; Musch, Guido; Melo, Marcos F Vidal; Venegas, Jose G; Harris, R Scott

2013-01-01

12

Effect of PEEP on regional ventilation and perfusion in the mechanically ventilated preterm lamb.  

PubMed

Improvement of gas exchange through closer matching of regional ventilation (V) and lung perfusion (Q) with the application of positive end-expiratory pressure (PEEP) was evaluated in vivo in six mechanically ventilated preterm lambs (107-126 days/145 days gestation). Changes in V and Q were determined from in vivo scintigraphic measurements in four lung regions with inhaled radioactive 81mKr, and infused 81mKr/dextrose and/or [99mTc]MAA as PEEP was applied at 2, 4, and 6 cm H2O in each animal. Dynamic compliance varied between 0.02 and 0.40 ml/cm H2O, which was consistent with surfactant deficiency. As PEEP was increased, the regional distribution of Q shifted from the rostral to the caudal lung regions (p less than 0.02 to less than 0.05), while that of V remained unchanged. Regional V/Q matching improved together with a trend towards improvement of arterial blood gases as PEEP was increased from 2 to 4 cm H2O. Pulmonary scintigraphy offers a noninvasive methodology for the quantitative assessment of regional V and Q matching in preterm lambs and may be clinically applicable to ventilated neonates. PMID:2666596

Schlessel, J S; Susskind, H; Joel, D D; Bossuyt, A; Harrold, W H; Zanzi, I; Chanana, A D

1989-08-01

13

Effect of PEEP on regional ventilation and perfusion in the mechanically ventilated preterm lamb  

SciTech Connect

Improvement of gas exchange through closer matching of regional ventilation (V) and lung perfusion (Q) with the application of positive end-expiratory pressure (PEEP) was evaluated in vivo in six mechanically ventilated preterm lambs (107-126 days/145 days gestation). Changes in V and Q were determined from in vivo scintigraphic measurements in four lung regions with inhaled radioactive 81mKr, and infused {sup 81m}Kr/dextrose and/or ({sup 99m}Tc)MAA as PEEP was applied at 2, 4, and 6 cm H{sub 2}O in each animal. Dynamic compliance varied between 0.02 and 0.40 ml/cm H{sub 2}O, which was consistent with surfactant deficiency. As PEEP was increased, the regional distribution of Q shifted from the rostral to the caudal lung regions (p less than 0.02 to less than 0.05), while that of V remained unchanged. Regional V/Q matching improved together with a trend towards improvement of arterial blood gases as PEEP was increased from 2 to 4 cm H{sub 2}O. Pulmonary scintigraphy offers a noninvasive methodology for the quantitative assessment of regional V and Q matching in preterm lambs and may be clinically applicable to ventilated neonates.

Schlessel, J.S.; Susskind, H.; Joel, D.D.; Bossuyt, A.; Harrold, W.H.; Zanzi, I.; Chanana, A.D. (Cornell Univ. Medical College, Manhasset, NY (USA))

1989-08-01

14

Ventilation-perfusion scan in the acutely ill patient with unilateral hyperlucent lung  

SciTech Connect

A patient with a unilateral hyperlucent lung with acute respiratory complaints is presented. A ventilation-perfusion scan was performed to rule out pulmonary embolism. The perfusion scan ( (/sup 99m/TC)MAA) showed peripheral perfusion defects in the hyperlucent lung. The ventilation study (/sup 133/Xe) demonstrated peripheral ventilatory defects on the single breath image in the hyperlucent lung, the filling in of these on the equilibrium view, and diffusely delayed washout in the affected lung. These findings were suggestive of the Swyer-James syndrome and critical in excluding the numerous other causes of unilateral hyperlucent lung, which are discussed. The importance of the ventilation-perfusion study (and particularly the ventilation scan) in the patient with unilateral hyperlucent lung and acute respiratory symptoms is stressed. In addition, a discussion of the Swyer-James syndrome is included.

Miller, M.B.; Caride, V.J.

1988-01-01

15

Asymptomatic large main pulmonary artery thromboembolism with a low-probability ventilation-perfusion lung scan.  

PubMed

The incidence of the interpretation of low-probability lung scans in asymptomatic patients with large central pulmonary embolisms and the prognostic implication of the ventilation-perfusion scan appearance in this clinical setting is not documented. PMID:11245113

Civelek, A C; Wang, E A; Barr, L; Urban, B A; Eng, J

2001-03-01

16

Tomography of regional ventilation and perfusion using krypton 81m in normal subjects and asthmatic patients  

Microsoft Academic Search

Single photon emission computed tomography, a rotating gamma camera, and continuous inhalation or infusion of krypton 81m (half life 13 seconds) were used to measure regional ventilation (V), perfusion (Q), and ventilation-perfusion (V\\/Q) ratios in five normal subjects in supine, prone, and lateral decubitus postures and in three asthmatic patients (supine posture only) before and after inhalation of 2.5 mg

D Orphanidou; J M Hughes; M J Myers; A R Al-Suhali; B Henderson

1986-01-01

17

OXYGEN UPTAKE IN A SPONTANEOUSLY VENTILATING, BLOOD-PERFUSED TROUT PREPARATION  

Microsoft Academic Search

SUMMARY 1. A spontaneously ventilating, blood-perfused trout preparation was used to examine gas exchange across the gills. 2. The blood flow rate and input oxygen content to the branchial circula- tion were manipulated to assess the contributions of perfusion and diffusion limitations to oxygen transfer. 3. Increases in the flow rate (£)), or the haematocrit (Hct) were positively correlated with

CHARLES DAXBOECKI; PETER S. DAVIE; STEVE F. PERRY; DAVID J. RANDALL

18

Separation of ventilation and perfusion related signals within EIT-data streams  

NASA Astrophysics Data System (ADS)

Electrical impedance tomography is a widely established technique for ventilation monitoring in the case of clinical research. To assess the capability of a patient's gas exchange, it is necessary to determine the regional supply of ventilation V as well as the local perfusion Q. Therefore, many approaches have been investigated to extract both signals from EIT-data, which would allow a V/Q-mapping. The challenge of this issue depends on the very weak perfusion related signal compared to the signal of ventilation. First approaches to visualize the perfusion were performed inducing apnea, ECG-gating or were based on Fourier series. Rather new techniques use principle component analysis (PCA) defining eigenvectors as a signal in time and thus try to determine "typical" ventilatory as well perfusion related signal streams. In this work, the algorithms of separation will be analyzed and compared (using apnea needs no separation and will not be discussed in this work).

Pikkemaat, R.; Leonhardt, S.

2010-04-01

19

Dynamic chest radiography with a flat-panel detector (FPD): ventilation-perfusion study  

NASA Astrophysics Data System (ADS)

Pulmonary ventilation and blood flow are reflected in dynamic chest radiographs as changes in X-ray translucency, i.e., pixel values. This study was performed to investigate the feasibility of ventilation-perfusion (V/Q) study based on the changes in pixel value. Sequential chest radiographs of a patient with ventilation-perfusion mismatch were obtained during respiration using a dynamic flat-panel detector (FPD) system. The lung area was recognized and average pixel value was measured in each area, tracking and deforming the region of interest. Inter-frame differences were then calculated, and the absolute values were summed in each respiratory phase. The results were visualized as ventilation, blood flow, V/Q ratio distribution map and compared to distribution of radioactive counts on ventilation and perfusion scintigrams. In the results, abnormalities were appeared as a reduction of changes in pixel values, and a correlation was observed between the distribution of changes in pixel value and those of radioactivity counts (Ventilation; r=0.78, Perfusion; r=0.77). V/Q mismatch was also indicated as mismatch of changes in pixel value, and a correlation with V/Q calculated by radioactivity counts (r=0.78). These results indicated that the present method is potentially useful for V/Q study as an additional examination in conventional chest radiography.

Tanaka, R.; Sanada, S.; Fujimura, M.; Yasui, M.; Tsuji, S.; Hayashi, N.; Okamoto, H.; Nanbu, Y.; Matsui, O.

2011-03-01

20

Optimization of isolated perfused/ventilated mouse lung to study hypoxic pulmonary vasoconstriction.  

PubMed

Hypoxic pulmonary vasoconstriction (HPV) is a compensatory physiological mechanism in the lung that optimizes the matching of ventilation to perfusion and thereby maximizes gas exchange. Historically, HPV has been primarily studied in isolated perfused/ventilated lungs; however, the results of these studies have varied greatly due to different experimental conditions and species. Therefore, in the present study, we utilized the mouse isolated perfused/ventilated lung model for investigation of the role of extracellular Ca(2+) and caveolin-1 and endothelial nitric oxide synthase expression on HPV. We also compared HPV using different perfusate solutions: Physiological salt solution (PSS) with albumin, Ficoll, rat blood, fetal bovine serum (FBS), or Dulbecco's Modified Eagle Medium (DMEM). After stabilization of the pulmonary arterial pressure (PAP), hypoxic (1% O2) and normoxic (21% O2) gases were applied via a ventilator in five-minute intervals to measure HPV. The addition of albumin or Ficoll with PSS did not induce persistent and strong HPV with or without a pretone agent. DMEM with the inclusion of FBS in the perfusate induced strong HPV in the first hypoxic challenge, but the HPV was neither persistent nor repetitive. PSS with rat blood only induced a small increase in HPV amplitude. Persistent and repetitive HPV occurred with PSS with 20% FBS as perfusate. HPV was significantly decreased by the removal of extracellular Ca(2+) along with addition of 1 mM EGTA to chelate residual Ca(2+) and voltage-dependent Ca(2+) channel blocker (nifedipine 1 ?M). PAP was also reactive to contractile stimulation by high K(+) depolarization and U46619 (a stable analogue of thromboxane A2). In summary, optimal conditions for measuring HPV were established in the isolated perfused/ventilated mouse lung. Using this method, we further confirmed that HPV is dependent on Ca(2+) influx. PMID:24015341

Yoo, Hae Young; Zeifman, Amy; Ko, Eun A; Smith, Kimberly A; Chen, Jiwang; Machado, Roberto F; Zhao, You-Yang; Minshall, Richard D; Yuan, Jason X-J

2013-04-01

21

Bronchogenic cyst causing a unilateral ventilation-perfusion defect on lung scan  

SciTech Connect

A 37-year-old woman had pleuritic chest pain, dyspnea, and normal findings on chest roentgenogram. Lung scan showed markedly diminished perfusion to the right lung with a matched ventilatory defect. Further evaluation revealed a bronchogenic cyst. After resection, the lung scan was normal. To our knowledge, this is the first report of a bronchogenic cyst causing a reversible, unilateral ventilation-perfusion defect on lung scan.

Berkowitz, K.A.; Fleischman, J.K.; Smith, R.L.

1988-06-01

22

Unusual ventilation perfusion scintigram in a case of immunologic pulmonary edema clinically simulating pulmonary embolism  

SciTech Connect

A case of immunologic pulmonary edema secondary to hydrochlorothiazide allergy developed in a 55-year-old woman that clinically simulated pulmonary embolism. The patient had abnormal washin images with normal washout images on an Xe-133 ventilation study. On the perfusion study, large bilateral central and posterior perfusion defects were present that showed an unusual mirror image pattern on the lateral and posterior oblique views. Resolution of radiographic and scintigraphic abnormalities occurred over a 3-day period in conjunction with corticosteroid therapy.

Campeau, R.J.; Faust, J.M.; Ahmad, S.

1987-11-01

23

The Effects of Acid Perfusion of the Esophagus on Ventilation and Respiratory Sensation  

Microsoft Academic Search

The relationship between gastroesophageal reflux (GER) and asthma remains controversial. Asthma symptoms worsen with GER, but are not consistently related to changes in lung function. The pur- pose of this study was to determine whether acid perfusion (AP) of the esophagus alters ventilation and causes respiratory symptoms. Nonasthmatic patients with normal lung function and esophageal disease (16 females and nine

STEPHEN K. FIELD; JOHN A. EVANS; LORNE M. PRICE

24

A General Approach to the Evaluation of Ventilation-Perfusion Ratios in Normal and Abnormal Lungs  

ERIC Educational Resources Information Center

Outlines methods for manipulating multiple gas data so as to gain the greatest amount of insight into the properties of ventilation-perfusion distributions. Refers to data corresponding to normal and abnormal lungs. Uses a two-dimensional framework with the respiratory gases of oxygen and carbon dioxide. (CS)

Wagner, Peter D.

1977-01-01

25

Ventilation-perfusion mismatch due to obstruction of pulmonary vein  

SciTech Connect

A lobar perfusion defect in the presence of a normal arterial phase in the pulmonary angiogram may be due to stasis secondary to compression of a pulmonary vein by a hilar or perhilar mass. In this report we present a patient with metastasis to the right lung and hilum by malignant melanoma. A lobar perfusion defect was present in an area of lung that appeared normal by radiograph. This defect was shown to be due to stagnating blood flow reflected by delayed intense capillary phase in that lobe and late opacification of the corresponding draining vein.

Mendelson, D.S.; Train, J.S.; Goldsmith, S.J.; Efremidis, S.C.

1981-12-01

26

Prediction of postoperative pulmonary function following thoracic operations. Value of ventilation-perfusion scanning  

SciTech Connect

Surgical resection of lung cancer is frequently required in patients with severely impaired lung function resulting from chronic obstructive pulmonary disease. Twenty patients with obstructive lung disease and cancer (mean preoperative forced expiratory volume in 1 second (FEV1) . 1.73 L) were studied preoperatively and postoperatively by spirometry and radionuclide perfusion, single-breath ventilation, and washout techniques to test the ability of these methods to predict preoperatively the partial loss of lung function by the resection. Postoperative FEV1 and forced vital capacity (FVC) were accurately predicted by the formula: postoperative FEV1 (or FVC) . preoperative FEV1 X percent function of regions of lung not to be resected (r . 0.88 and 0.95, respectively). Ventilation and perfusion scans are equally effective in prediction. Washout data add to the sophistication of the method by permitting the qualitative evaluation of ventilation during tidal breathing. Criteria for patients requiring the study are suggested.

Bria, W.F.; Kanarek, D.J.; Kazemi, H.

1983-08-01

27

Evaluation of pulmonary perfusion in lung regions showing isolated xenon-133 ventilation washout defects  

SciTech Connect

Xenon-133 washout phase imaging is often used to help determine whether the etiology of a perfusion defect is embolic or due to pulmonary parenchymal pathology, such as chronic obstructive pulmonary disease. This study was designed to evaluate the pulmonary blood flow patterns associated with isolated defects on xenon washout images. Scintigraphic lung studies were reviewed until 100 cases with abnormal ventilation results were obtained. Ventilation abnormalities were compared with the corresponding perfusion scan results at the same anatomic site. Of the 208 individual lung regions with xenon abnormalities, 111 showed isolated washout defects (that is, with normal washin). Ninety-four of these 111 sites showed either normal perfusion or a small, nonsegmental corresponding perfusion defect. Three segmental perfusion defects were noted in association with isolated xenon retention. In each of these cases, however, the patient was felt actually to have pulmonary embolism. Thus, it is recommended that, for interpretation of scintigraphic images in the assessment of pulmonary embolism, lung pathology associated with isolated xenon retention not be considered a potential cause for large or segmental perfusion defects.

Bushnell, D.L.; Sood, K.B.; Shirazi, P.; Pal, I. (VA Hines Hospital, IL (USA))

1990-08-01

28

Effect of surfactant on ventilation-induced mediator release in isolated perfused mouse lungs.  

PubMed

The human acute respiratory distress syndrome (ARDS) is a severe pulmonary complication with high mortality rates. To support their vital functions, patients suffering from ARDS are mechanically ventilated. Recently it was shown that low tidal volume ventilation reduces mortality and pro-inflammatory mediator release in these patients, suggesting biotrauma as a side effect of mechanical ventilation. Because the application of exogenous surfactant has been proposed as a treatment for ARDS, we investigated the effect of surfactant on ventilation-induced release of tumor necrosis factor (TNF), interleukin-6 (IL-6) and 6-keto-PGF(1 alpha) (the stable metabolite of prostacyclin) in isolated perfused mouse lungs ventilated with high end-inspiratory pressures. Instillation of 100mg/kg surfactant into the lungs was well tolerated and improved tidal volume, pulmonary compliance and alveolar expansion. Exogenous surfactant increased the ventilation-induced liberation of TNF and IL-6 into the perfusate, but had no effect on the release of 6-keto-PGF(1 alpha). The surfactant preparation used reduced baseline TNF production by murine alveolar macrophages, indicating that the exaggeration of ventilation-induced TNF release cannot be explained by a direct effect of surfactant on these cells. We hypothesize that ventilation-induced mediator release is explained by stretching of lung cells, which is reinforced by surfactant. The findings that in this model of ventilation-induced lung injury exogenous surfactant at the same time improved lung functions and enhanced mediator release suggest that surfactant treatment may prevent barotrauma and augment biotrauma. PMID:12406668

Stamme, Cordula; Brasch, Frank; von Bethmann, Alexander; Uhlig, Stefan

2002-01-01

29

Myocardial perfusion as assessed by thallium-201 scintigraphy during the discontinuation of mechanical ventilation in ventilator-dependent patients  

SciTech Connect

Patients who cannot be separated from mechanical ventilation (MV) after an episode of acute respiratory failure often have coexisting coronary artery disease. The authors hypothesized that increased left ventricular (LV) wall stress during periods of spontaneous ventilation (SV) could alter myocardial perfusion in these patients. Using thallium-201 (201TI) myocardial scintigraphy, the authors studied the occurrence of myocardial perfusion abnormalities during periods of SV in 15 MV-dependent patients (nine women, six men; aged 71 {plus minus} 7 yr, mean {plus minus} SD). Fourteen of these patients were studied once with 201TI myocardial scintigraphy during intermittent mechanical ventilation (IMV) and again on another day, after at least 10 min of SV through a T-piece. One patient was studied during SV only. Thirteen of 14 of the patients (93%) studied during MV had abnormal patterns of initial myocardial 201TI uptake, but only 1 patient demonstrated redistribution of 201TI on delayed images. The remainder of the abnormalities observed during MV were fixed defects. SV produced significant alterations of myocardial 201TI distribution or transient LV dilation, or both, in 7 of the 15 patients (47%). Four patients demonstrated new regional decreases of LV myocardial thallium concentration with redistribution of the isotope on delayed images. The patient studied only during SV also had myocardial 201TI defects with redistribution. Five patients (3 also having areas of 201TI redistribution) had transient LV dilation during SV.

Hurford, W.E.; Lynch, K.E.; Strauss, H.W.; Lowenstein, E.; Zapol, W.M. (Department of Anesthesia, Harvard Medical School, Massachusetts General Hospital, Boston (USA))

1991-06-01

30

Radiographic parenchymal opacity, matching perfusion defect, and normal ventilation: a sign of pulmonary embolism. Work in progress  

SciTech Connect

By conventional criteria, perfusion defects that correspond to radiographic parenchymal opacities of similar size have less diagnostic significance for pulmonary embolism (PE) than perfusion defects in areas that are radiographically clear, regardless of the findings on ventilation scan. It was proposed that the demonstration of normal ventilation in areas with matched radiographic opacity and perfusion defects does support the diagnosis of PE. To test this hypothesis, a retrospective review was done of selected cases from a consecutive series of 85 pulmonary angiography studies. Cases were reviewed if the following criteria were met: chest radiography, ventilation-perfusion scintigraphy, and angiography of the relevant regions had all been performed within 24 hours of one another, and there was a radiographic opacity corresponding to the perfusion defect. Sixteen cases fulfilled these criteria. Six patients had normal ventilation in the regions of the radiographic infiltrate and perfusion defect, and all had PE. No patient had an area of opacity and perfusion defect and normal ventilation without PE.

Strauss, E.B.; Sostman, H.D.; Gottschalk, A.

1987-05-01

31

Ventilation-perfusion lung scanning in patients detected by a screening program for early lung carcinoma  

SciTech Connect

Ventilation-perfusion (V-P) lung scans obtained in 114 patients in a screening program for the early detection of lung cancer were reviewed, and abnormalities were correlated with radiographic and surgical findings. Eighty-seven patients eventually had a tissue diagnosis of carcinoma; 65 (75%) had a perfusion defect and 56 (67%) had a ventilation abnormality at the tumor site. Lobar or segmental perfusion abnormalities were present at the tumor site in two of 13 patients whose lung cancer could not be localized by chest radiographs. However, 12 of these 13 patients and 54% of those with radiographically visible lesions had perfusion abnormalities in other lung regions. Twenty-seven patients with suspected carcinoma who were subsequently proved to have benign lesions had V-P abnormalities similar to those in patients with lung cancer. Thus, no pattern of V-P abnormalities allowed lung cancer in this screened population to be reliably distinguished from coexisting airway disease or nonmalignant pulmonary masses. V-P lung studies have a limited role in the early detection of lung cancer.

Katz, R.D.; Alderson, P.O.; Tockman, M.S.

1981-10-01

32

Ventilation-perfusion scanning and pulmonary angiography: correlation in clinical high-probability pulmonary embolism  

SciTech Connect

During a 3-year period, 173 clinically selected patients underwent pulmonary angiography to confirm or exclude acute pulmonary embolism. All patients had undergone ventilation-perfusion (V/Q) scanning (167 patients) or perfusion scanning alone (six) before angiography. Angiography was done because the results of the V/Q scanning did not satisfy the clinician's needs for certainty. The results of the V/Q and studies were compared to determine the relative accuracy of V/Q scanning in this clinical setting. Pulmonary embolism was found in seven (15%) of 47 patients with low-probability scans, 11 (32%) of 34 patients with intermediate-probability scans, 22 (39%) of 57 patients with indeterminate scans, and 23 (66%) of 35 patients with high-probability scans. In this clinically selected population, low-probability scans were more accurate in excluding pulmonary embolism than were high-probability scans in establishing that diagnosis.

Braun, S.D.; Newman, G.E.; Ford, K.; Miller, G.A.; Coleman, R.E.; Dunnick, N.R.

1984-11-01

33

Ventilation-perfusion scanning and pulmonary angiography: correlation in clinical high-probability pulmonary embolism  

SciTech Connect

During a 3-year period, 173 clinically selected patients underwent pulmonary angiography to confirm or exclude acute pulmonary embolism. All patients had undergone ventilation-perfusion (V/Q) scanning (167 patients) or perfusion scanning alone (six) before angiography. Angiography was done because the results of the V/Q scanning did not satisfy the clinician's needs for certainty. The results of the V/Q and angiographic studies were compared to determine the relative accuracy of V/Q scanning in this clinical setting. Pulmonary embolism was found in seven (15%) of 47 patients with low-probability scans, 11 (32%) of 34 patients with intermediate-probability scans, 22 (39%) of 57 patients with indeterminate scans, and 23 (66%) of 35 patients with high-probability scans. In this clinically selected population, low-probability scans were more accurate in excluding pulmonary embolism than were high-probability scans in establishing that diagnosis.

Braun, S.D.; Newman, G.E.; Ford, K.; Miller, G.A.; Coleman, R.E.; Dunnick, N.R.

1984-11-01

34

Ventilation-perfusion scintigraphy in an adult with congenital unilateral hyperlucent lung  

SciTech Connect

A variety of congenital and acquired etiologies can give rise to the radiographic finding of a unilateral hyperlucent lung. An unusual case of congenital lobar emphysema diagnosed in a young adult following the initial discovery of a hyperexpanded, hyperlucent lung is reported. Although subsequent bronchoscopy and radiologic studies detailed extensive anatomic abnormalities, functional imaging also played an important role in arriving at this rare diagnosis. In particular, ventilation-perfusion scintigraphy identified the small contralateral lung as the functional lung and helped narrow the differential diagnosis to etiologies involving obstructive airway disorders.

Wegener, W.A.; Velchik, M.G. (Hospital of the University of Pennsylvania, Philadelphia (USA))

1990-10-01

35

An expert system for the interpretation of radionuclide ventilation-perfusion lung scans  

NASA Astrophysics Data System (ADS)

One of the most commonly performed imaging procedures in nuclear medicine is the lung scan for suspected pulmonary embolism. The purpose of this research was to develop an expert system that interprets lung scans and gives a probability of pulmonary embolism. Three standard ventilation and eight standard perfusion images are first outlined manually. Then the images are normalized. Because lung size varies from patient to patient, each image undergoes a two-dimensional stretch onto a standard-size mask. To determine the presence of regional defects in ventilation or perfusion, images are then compared on a pixel by pixel basis with a normal database. This database consists of 21 normal studies that represent the variation in activity between subjects. Any pixel that falls more than 2.2 standard deviations below the normal file is flagged as possibly abnormal. To reduce statistical fluctuations, a clustering criteria is applied such that each pixel must have at least two continuous neighbors that are abnormal for a pixel to be flagged abnormal.

Gabor, Frank V.; Datz, Frederick L.; Christian, Paul E.; Gullberg, Grant T.; Morton, Kathryn A.

1993-09-01

36

Feasibility of Combining MR Perfusion, Angiography, and 3He Ventilation Imaging for Evaluation of Lung Function in a Porcine Model  

PubMed Central

Rationale and Objective To assess the feasibility of combining magnetic resonance (MR) perfusion, angiography, and 3He ventilation imaging for the evaluation of lung function in a porcine model. Materials and Methods Fourteen consecutive porcine models with externally delivered pulmonary emboli and/or airway occlusions were examined with MR perfusion, angiography, and 3He ventilation imaging. Ultrafast gradient-echo sequences were used for 3D perfusion and angiographic imaging, in conjunction with the use of contrast-agent injections. 2D multiple-section 3He imaging was performed subsequently via the inhalation of hyperpolarized 3He gas. The diagnostic accuracy of MR angiography for detecting pulmonary emboli was determined by two reviewers. The diagnostic confidence for different combinations of MR techniques was rated on the basis of a 5-point grading scale (5 = definite). Results The sensitivity, specificity, and accuracy of MR angiography for detecting pulmonary emboli were approximately 85.7%, 90.5%, and 88.1%, respectively. The interobserver agreement was very strong (k = 0.82). There was a clear tendency for confidence to increase when first perfusion and then ventilation imaging were added to the angiographic image (Wilcoxon signed ranks test, P = 0.03). Conclusion The combination of the three methods of MR perfusion, angiography, and 3H ventilation imaging may provide complementary information on abnormal lung anatomy and function.

Hong, Cheng; Leawoods, Jason C.; Yablonskiy, Dmitriy A.; Leyendecker, John R.; Bae, Kyongtae T.; Pilgram, Thomas K.; Woodard, Pamela K.; Conradi, Mark S.; Zheng, Jie

2007-01-01

37

Assessment of the intrapulmonary ventilation-perfusion distribution after the Fontan procedure for complex cardiac anomalies: Relation to pulmonary hemodynamics  

SciTech Connect

In 12 patients who underwent the Fontan procedure for complex cardiac anomalies, lung scanning with xenon-133 was performed to assess the intrapulmonary ventilation-perfusion distribution, and comparison was made with a control group. All data were then analyzed in relation to either pre- or postoperative pulmonary hemodynamic data. In ventilation scans, the intrapulmonary distribution in the right lung was almost normal. In perfusion scans, an abnormal increased upper to lower lobe perfusion ratio greater than the normal value found in the control group was noted in seven patients (58.3%). There was a significant correlation (p less than 0.02) between the upper to lower lobe perfusion ratio and postoperative pulmonary vascular resistance. Furthermore, this perfusion ratio correlated inversely with the preoperative (p less than 0.005) and postoperative (p less than 0.02) right pulmonary artery area index, defined as the ratio of cross-sectional area to the normal value. Of five patients with less than 90% arterial oxygen saturation, four showed an abnormal distribution of pulmonary blood flow greater than the normal perfusion ratio. No patient had evidence of a pulmonary arteriovenous fistula by the echocardiographic contrast study. These results suggest that abnormal distribution of pulmonary blood flow to the upper lung segment may develop in patients after the Fontan procedure, and that insufficient size of the pulmonary artery before operation and the consequent postoperative elevation of pulmonary vascular resistance may be responsible for this perfusion abnormality.

Matsushita, T.; Matsuda, H.; Ogawa, M.; Ohno, K.; Sano, T.; Nakano, S.; Shimazaki, Y.; Nakahara, K.; Arisawa, J.; Kozuka, T. (Osaka Univ. Medical School (Japan))

1990-03-15

38

Reduction of mismatch of global ventilation and perfusion on exercise is related to exercise capacity in chronic heart failure.  

PubMed Central

BACKGROUND--The inability to match lung perfusion to ventilation because of a reduced cardiac output on exercise contributes to reduced exercise capacity in chronic heart failure. OBJECTIVE--To quantify ventilation to perfusion matching at rest and at peak exercise in patients with chronic heart failure and relate this to haemodynamic and ventilatory variables of exercise capacity. DESIGN--Eight men in New York Heart Association class II underwent maximal bicycle ergometry with expired gas analysis. MAIN OUTCOME MEASURES--On separate days, ventilation and perfusion gamma camera imaging was performed at rest, and at 80% of previous peak exercise heart rate during bicycle ergometry. The vertical distribution of mismatch between ventilation and perfusion (V/Q) was estimated from subtracted profiles of activity (ventilation and perfusion) to derive a numerical index of global mismatch. RESULTS--Maximal mean (SD) oxygen consumption on bicycle ergometry was 16.0 (4.5) ml min-1 kg-1. There was a reduction in the global V/Q mismatch index from 23.96 (5.90) to 14.88 (7.90) units (p < 0.01) at rest and at peak exercise. Global V/Q mismatch index at peak exercise correlated negatively with maximal minute ventilation (R = -0.90, p < 0.01) and with maximal mean arterial pressure (R = -0.79, p < 0.05), although no relation was seen with maximal oxygen consumption. The reduction in global V/Q mismatch index from rest to peak exercise correlated with maximal oxygen consumption (R = 0.88, p < 0.01), and with maximal minute ventilation (R = 0.87, p < 0.01). CONCLUSIONS--During exercise in patients with chronic heart failure, there is a reduction in the global V/Q mismatch index. A lower global V/Q mismatch index at peak exercise is associated with higher maximal ventilation. The reduction in global V/Q mismatch index on exercise correlates well with maximal exercise capacity. This may imply that the inability to perfuse adequately all regions of lung on exercise and match this to ventilation is a factor determining exercise capacity in chronic heart failure.

Uren, N G; Davies, S W; Agnew, J E; Irwin, A G; Jordan, S L; Hilson, A J; Lipkin, D P

1993-01-01

39

Tomography of regional ventilation and perfusion using krypton 81m in normal subjects and asthmatic patients.  

PubMed Central

Single photon emission computed tomography, a rotating gamma camera, and continuous inhalation or infusion of krypton 81m (half life 13 seconds) were used to measure regional ventilation (V), perfusion (Q), and ventilation-perfusion (V/Q) ratios in five normal subjects in supine, prone, and lateral decubitus postures and in three asthmatic patients (supine posture only) before and after inhalation of 2.5 mg nebulised salbutamol. Vertical and horizontal gradients of V, Q, and V/Q were examined at three levels in each lung in regions of 1.9 cm3 size. In normal subjects V and Q increased along the axis of gravity in all postures and at all levels in the lung except for V in the prone position. Smaller horizontal gradients were found with an increase in V and Q from caudal to cranial--again except in the prone posture, where the gradient was slightly reversed. Constraint to outward motion of the ventral chest and abdominal wall is the most likely explanation for the different behaviour in the prone posture. In chronic asthma the vertical gradients of V and V/Q were the reverse of normal, but the Q gradient was normal. Bronchodilator treatment did not affect the vertical or horizontal gradients significantly, but analysis of individual regions showed that, relatively, V/Q worsened in 42% of them; this was associated in two thirds with an increase in fractional Q. After inhalation of beta agonist local vasodilatation may influence V/Q ratios in some units more than bronchodilatation. Images

Orphanidou, D; Hughes, J M; Myers, M J; Al-Suhali, A R; Henderson, B

1986-01-01

40

Characterization of the Isolated, Ventilated, and Instrumented Mouse Lung Perfused with Pulsatile Flow  

PubMed Central

The isolated, ventilated and instrumented mouse lung preparation allows steady and pulsatile pulmonary vascular pressure-flow relationships to be measured with independent control over pulmonary arterial flow rate, flow rate waveform, airway pressure and left atrial pressure. Pulmonary vascular resistance is calculated based on multi-point, steady pressure-flow curves; pulmonary vascular impedance is calculated from pulsatile pressure-flow curves obtained at a range of frequencies. As now recognized clinically, impedance is a superior measure of right ventricular afterload than resistance because it includes the effects of vascular compliance, which are not negligible, especially in the pulmonary circulation. Three important metrics of impedance - the zero hertz impedance Z0, the characteristic impedance ZC, and the index of wave reflection RW - provide insight into distal arterial cross-sectional area available for flow, proximal arterial stiffness and the upstream-downstream impedance mismatch, respectively. All results obtained in isolated, ventilated and perfused lungs are independent of sympathetic nervous system tone, volume status and the effects of anesthesia. We have used this technique to quantify the impact of pulmonary emboli and chronic hypoxia on resistance and impedance, and to differentiate between sites of action (i.e., proximal vs. distal) of vasoactive agents and disease using the pressure dependency of ZC. Furthermore, when these techniques are used with the lungs of genetically engineered strains of mice, the effects of molecular-level defects on pulmonary vascular structure and function can be determined.

Vanderpool, Rebecca R.; Chesler, Naomi C.

2011-01-01

41

Spatial correspondence of 4D CT ventilation and SPECT pulmonary perfusion defects in patients with malignant airway stenosis  

NASA Astrophysics Data System (ADS)

To determine the spatial overlap agreement between four-dimensional computed tomography (4D CT) ventilation and single photon emission computed tomography (SPECT) perfusion hypo-functioning pulmonary defect regions in a patient population with malignant airway stenosis. Treatment planning 4D CT images were obtained retrospectively for ten lung cancer patients with radiographically demonstrated airway obstruction due to gross tumor volume. Each patient also received a SPECT perfusion study within one week of the planning 4D CT, and prior to the initiation of treatment. Deformable image registration was used to map corresponding lung tissue elements between the extreme component phase images, from which quantitative three-dimensional (3D) images representing the local pulmonary specific ventilation were constructed. Semi-automated segmentation of the percentile perfusion distribution was performed to identify regional defects distal to the known obstructing lesion. Semi-automated segmentation was similarly performed by multiple observers to delineate corresponding defect regions depicted on 4D CT ventilation. Normalized Dice similarity coefficient (NDSC) indices were determined for each observer between SPECT perfusion and 4D CT ventilation defect regions to assess spatial overlap agreement. Tidal volumes determined from 4D CT ventilation were evaluated versus measurements obtained from lung parenchyma segmentation. Linear regression resulted in a linear fit with slope = 1.01 (R2 = 0.99). Respective values for the average DSC, NDSC1 mm and NDSC2 mm for all cases and multiple observers were 0.78, 0.88 and 0.99, indicating that, on average, spatial overlap agreement between ventilation and perfusion defect regions was comparable to the threshold for agreement within 1-2 mm uncertainty. Corresponding coefficients of variation for all metrics were similarly in the range: 0.10%-19%. This study is the first to quantitatively assess 3D spatial overlap agreement between clinically acquired SPECT perfusion and specific ventilation from 4D CT. Results suggest high correlation between methods within the sub-population of lung cancer patients with malignant airway stenosis.

Castillo, Richard; Castillo, Edward; McCurdy, Matthew; Gomez, Daniel R.; Block, Alec M.; Bergsma, Derek; Joy, Sarah; Guerrero, Thomas

2012-04-01

42

Blood flow redistribution and ventilation-perfusion mismatch during embolic pulmonary arterial occlusion.  

PubMed

Acute pulmonary embolism causes redistribution of blood in the lung, which impairs ventilation/perfusion matching and gas exchange and can elevate pulmonary arterial pressure (PAP) by increasing pulmonary vascular resistance (PVR). An anatomically-based multi-scale model of the human pulmonary circulation was used to simulate pre- and post-occlusion flow, to study blood flow redistribution in the presence of an embolus, and to evaluate whether reduction in perfused vascular bed is sufficient to increase PAP to hypertensive levels, or whether other vasoconstrictive mechanisms are necessary. A model of oxygen transfer from air to blood was included to assess the impact of vascular occlusion on oxygen exchange. Emboli of 5, 7, and 10 mm radius were introduced to occlude increasing proportions of the vasculature. Blood flow redistribution was calculated after arterial occlusion, giving predictions of PAP, PVR, flow redistribution, and micro-circulatory flow dynamics. Because of the large flow reserve capacity (via both capillary recruitment and distension), approximately 55% of the vasculature was occluded before PAP reached clinically significant levels indicative of hypertension. In contrast, model predictions showed that even relatively low levels of occlusion could cause localized oxygen deficit. Flow preferentially redistributed to gravitationally non-dependent regions regardless of occlusion location, due to the greater potential for capillary recruitment in this region. Red blood cell transit times decreased below the minimum time for oxygen saturation (<0.25 s) and capillary pressures became high enough to initiate cell damage (which may result in edema) only after ~80% of the lung was occluded. PMID:22140626

Burrowes, K S; Clark, A R; Tawhai, M H

43

Blood flow redistribution and ventilation-perfusion mismatch during embolic pulmonary arterial occlusion  

PubMed Central

Acute pulmonary embolism causes redistribution of blood in the lung, which impairs ventilation/perfusion matching and gas exchange and can elevate pulmonary arterial pressure (PAP) by increasing pulmonary vascular resistance (PVR). An anatomically-based multi-scale model of the human pulmonary circulation was used to simulate pre- and post-occlusion flow, to study blood flow redistribution in the presence of an embolus, and to evaluate whether reduction in perfused vascular bed is sufficient to increase PAP to hypertensive levels, or whether other vasoconstrictive mechanisms are necessary. A model of oxygen transfer from air to blood was included to assess the impact of vascular occlusion on oxygen exchange. Emboli of 5, 7, and 10 mm radius were introduced to occlude increasing proportions of the vasculature. Blood flow redistribution was calculated after arterial occlusion, giving predictions of PAP, PVR, flow redistribution, and micro-circulatory flow dynamics. Because of the large flow reserve capacity (via both capillary recruitment and distension), approximately 55% of the vasculature was occluded before PAP reached clinically significant levels indicative of hypertension. In contrast, model predictions showed that even relatively low levels of occlusion could cause localized oxygen deficit. Flow preferentially redistributed to gravitationally non-dependent regions regardless of occlusion location, due to the greater potential for capillary recruitment in this region. Red blood cell transit times decreased below the minimum time for oxygen saturation (<0.25 s) and capillary pressures became high enough to initiate cell damage (which may result in edema) only after ~80% of the lung was occluded.

Burrowes, K. S.; Clark, A. R.; Tawhai, M. H.

2011-01-01

44

Thoracic epidural anesthesia as an adjunct to general anesthesia for cardiac surgery: Effects on ventilation-perfusion relationships  

Microsoft Academic Search

Objective: To determine the effects of thoracic epidural anesthesia (TEA) on ventilation-perfusion (VA\\/Q) relationships, atelectasis, and oxygenation before and after coronary artery bypass graft surgery (CABG).Design: Prospective, controlled, unblinded, randomized trial.Setting: Cardiothoracic clinic at a major university referral center.Participants: Twenty-eight patients undergoing elective CABG.Interventions: Perioperative and postoperative TEA was added to general anesthesia (GA) in 14 patients, and 14 patients

Arne Tenling; Per-Olof Joachimsson; Hans Tydén; Göran Wegenius; Göran Hedenstierna

1999-01-01

45

Influence of perfusion and ventilation scans on therapeutic decision making and outcome in cases of possible embolism  

SciTech Connect

The authors examined the influence of perfusion (Q) and ventilation (V) scans on therapeutic decision making and outcome among 229 patients referred for lung scans because embolism was suggested and found that specific V/Q scan patterns strongly influenced postscan decisions regarding initiation, maintenance or cessation of heparin therapy. These therapeutic decisions bore a relationship to outcome (recurrences and death) and disclosed decision-making deficits that need remedy by future investigational and educational efforts. 25 references, 5 tables.

Mercandetti, A.J.; Kipper, M.S.; Moser, K.M.

1985-02-01

46

Ventilation-perfusion inequality in the human lung is not increased following no-decompression-stop hyperbaric exposure  

Microsoft Academic Search

Venous gas bubbles occur in recreational SCUBA divers in the absence of decompression sickness, forming venous gas emboli\\u000a (VGE) which are trapped within pulmonary circulation and cleared by the lung without overt pathology. We hypothesized that\\u000a asymptomatic VGE would transiently increase ventilation-perfusion mismatch due to their occlusive effects within the pulmonary\\u000a circulation. Two sets of healthy volunteers (n = 11, n = 12) were

Gaea Schwaebe Moore; Stewart C. Wong; Chantal Darquenne; Tom S. Neuman; John B. West; G. Kim Prisk

2009-01-01

47

Relative accuracy of two diagnostic schemes for detection of pulmonary embolism by ventilation-perfusion scintigraphy  

SciTech Connect

Two diagnostic schemes for detection of pulmonary embolism by ventilation-perfusion (V-P) scintigraphy were compared for relative accuracy by two groups of observers interpreting 70 V-P scintiscans. Observers in Group B, who used the criteria recently proposed by Biello et al., had a significantly smaller average number of indeterminate interpretations (41%) than did the observers in Group A (55%), who used a simpler scheme (p less than 0.05). In addition, Group B showed a slight improvement in positive predictive value without a deterioration in the negative predictive value compared with Group A. Along with this improvement in diagnostic performance, Group B achieved a significant reduction in interobserver variability compared with Group A for patients without pulmonary embolism (p less than 0.05). There was no significant difference in interobserver variability between the two groups for patients with pulmonary embolism. The diagnostic scheme introduced by Biello et al. represents a useful improvement for the diagnosis of pulmonary embolism by V-P imaging.

Carter, W.D.; Brady, T.M.; Keyes, J.W. Jr.; Thrall, J.H.; Greenhouse, J.B.; Biello, D.R.; Siegel, B.A.; Alderson, P.O.; Brady, T.J.

1982-11-01

48

Diagnosis of pulmonary embolism: ventilation perfusion scintigraphy versus helical computed tomography pulmonary angiography.  

PubMed

The present study compared the accuracy of ventilation perfusion scintigraphy (VQS) and CT pulmonary angiography (CTPA) for the diagnosis of pulmonary embolism. This was a prospective observational study of 112 patients with suspected pulmonary embolism (PE) who could be studied with both investigations within 24 h. Results were compared to final diagnosis at completion of 6-month follow up, using receiver operating characteristic (ROC) analysis. Pulmonary embolism was diagnosed in 27 referred patients (24%). The sensitivity and specificity of VQS and CTPA were similar to that reported from the literature. A normal VQ scan had the highest negative predictive value (100%), while a high-probability VQ scan had the highest positive predictive value (92%). There was no overall difference (area under the ROC curve (AUC)) between VQS (AUC (95% CI) = 0.82 (0.75,0.89)) and CTPA (AUC = 0.88 (0.81,0.94)) for the diagnosis of PE. Among patients with abnormal chest X-rays, CTPA (AUC 0.90 (0.83,0.97)) appeared somewhat better than VQS (AUC 0.78 (0.68,0.88)) but this difference did not reach statistical significance. In this instance, CTPA is at least as accurate as VQS and may provide an opportunity to make alternative diagnoses. PMID:15727607

Macdonald, W B G; Patrikeos, A P; Thompson, R I; Adler, B D; van der Schaaf, A A

2005-02-01

49

Planar ventilation-perfusion imaging for pulmonary embolism: the case for "outcomes" medicine.  

PubMed

Single-photon emission computed tomography (SPECT) has been a significant advancement in scintigraphy, impacting many areas of diagnosis. It has begun to find use in ventilation-perfusion (V/Q) scintigraphy. However, its utility has been limited in the United States because of a lack of an optimal and Food and Drug Administration-approved SPECT ventilatory agent. Although SPECT V/Q can show more and smaller mismatches than planar studies, there is persistent debate regarding the clinical significance of these smaller pulmonary emboli (PE); they may be neither clinically significant nor require treatment. Available data suggest that planar V/Q, SPECT V/Q, and computed tomographic pulmonary angiography (CTPA) have similar false-negative rates and thus have a similar impact on outcomes. In most cases, emergency department physicians are the first to encounter patients who may have PE, and they frequently use an imaging study as part of the evaluation. We discuss the rational for triaging patients to different imaging modalities with the use of chest radiography and the strengths and weaknesses of each modality. Detailed anatomy is an advantage of CTPA, breast radiation dose is reduced with scintigraphy, and imaging is quicker and more detailed with SPECT. We also review planar and SPECT V/Q and CTPA from the differing vantage points of diagnostic accuracy vs patient outcomes. Whatever modality their patients require, physicians can be confident that they are all similarly efficacious at diagnosing clinically relevant emboli. PMID:22117808

Freeman, Leonard M; Glaser, Joseph E; Haramati, Linda B

2012-01-01

50

Krypton 81m ventilation/perfusion ratios (V/Q) measured in lateral decubitus in pulmonary embolism (P. E. )  

SciTech Connect

In normal subjects lateral decubitis induces in both independent (lower) and nondependent lung (upper), major changes in perfusion, ventilation and V/Q ratios which can be studied with the short life radioisotope Krypton 81m. Regional V/Q are computed from ventilation and perfusion scans, successively obtained with a gamma camera linked to a computer by continuous inhalation or infusion of this gas during tidal breathing. They were displayed as a color coded functional image. To assess the effect of posture on V/Q in P.E. and other diseases which decrease the regional perfusion, 32 patients with unilateral lung diseases were studied in supine posture and both lateral decubitis: 8 with proved P.E., (3 out of them having radiological opacity matching the perfusion defect), 9 with bullous emphysema, 6 with bronchogenic carcinoma, 9 with acute bacterial pneumonia. V/Q were computed in the region of the perfusion defect. In P.E. the mean V/Q was high (1.92 +- 0.6 SD), and did not change whatever the posture. Conversely major changes of V/Q were induced with postural changes in bullous emphysema and lung carcinoma whatever the V/Q in patient supine. In pneumonia low V/Q were observed in supine posture (.73 +- .2). They decreased significantly when the pneumonia was dependent (.53 +- .2 p < 0.02) and increased in the controlateral decubitis (1.07 +- .3, p < 0.001). Since posture has no or little effect on regional V/Q in P.E., it can be used to discriminate P.E., even in the case of radiological opacity, from other unilateral disease inducing perfusion defect.

Meignan, M.; Cinotti, L.; Harf, A.; Oliveira, L.; Simonneau, G.

1984-01-01

51

The Effect of Positive Centrifugal Acceleration Upon the Distribution of Ventilation and Perfusion Within the Human Lung, and Its Relation to Pulmonary Arterial and Intraoesophageal Pressures  

Microsoft Academic Search

The influence of gravity on the distributions of ventilation and blood flow, as demonstrated by the effects of posture, is discussed and explained on the theoretical basis of gravitational gradients of pressure within the lung tissue and blood vessels. Positive acceleration steepens these gradients so that measurement of regional ventilation and perfusion in subjects riding on a human centrifuge allows

D. H. Glaister

1967-01-01

52

The Role of Hypoventilation and Ventilation-Perfusion Redistribution in Oxygen-induced Hypercapnia during Acute Exacerbations of Chronic Obstructive Pulmonary Disease  

Microsoft Academic Search

The detailed mechanisms of oxygen-induced hypercapnia were ex- amined in 22 patients during an acute exacerbation of chronic ob- structive pulmonary disease. Ventilation, cardiac output, and the distribution of ventilation-perfusion ( ) ratios were measured using the multiple inert gas elimination technique breathing air and then 100% oxygen through a nose mask. Twelve patients were classified as retainers (R) when

TRACEY D. ROBINSON; DAVID B. FREIBERG; JEFF A. REGNIS; IVEN H. YOUNG

53

A Short Period of Ventilation without Perfusion Seems to Reduce Atelectasis without Harming the Lungs during Ex Vivo Lung Perfusion  

PubMed Central

To evaluate the lung function of donors after circulatory deaths (DCDs), ex vivo lung perfusion (EVLP) has been shown to be a valuable method. We present modified EVLP where lung atelectasis is removed, while the lung perfusion is temporarily shut down. Twelve pigs were randomized into two groups: modified EVLP and conventional EVLP. When the lungs had reached 37°C in the EVLP circuit, lung perfusion was temporarily shut down in the modified EVLP group, and positive end-expiratory pressure (PEEP) was increased to 10?cm H2O for 10 minutes. In the conventional EVLP group, PEEP was increased to 10?cm H2O for 10 minutes with unchanged lung perfusion. In the modified EVLP group, the arterial oxygen partial pressure (PaO2) was 18.5 ± 7.0?kPa before and 64.5 ± 6.0?kPa after the maneuver (P < 0.001). In the conventional EVLP group, the PaO2 was 16.8 ± 3.1?kPa and 46.8 ± 2.7?kPa after the maneuver (P < 0.01; P < 0.01). In the modified EVLP group, the pulmonary graft weight was unchanged, while in the conventional EVLP group, the pulmonary graft weight was significantly increased. Modified EVLP with normoventilation of the lungs without ongoing lung perfusion for 10 minutes may eliminate atelectasis almost completely without harming the lungs.

Pierre, Leif

2013-01-01

54

Effects of helium-oxygen on respiratory mechanics, gas exchange, and ventilation-perfusion relationships in a porcine model of stable methacholine-induced bronchospasm  

Microsoft Academic Search

Objective: To explore the consequences of helium\\/oxygen (He\\/O2) inhalation on respiratory mechanics, gas exchange, and venti- lation-perfusion (VA\\/Q) relation- ships in an animal model of severe induced bronchospasm during me- chanical ventilation. Design: Pro- spective, interventional study. Setting: Experimental animal labora- tory, university hospital. Interven- tions: Seven piglets were anesthe- tized, paralyzed, and mechanically ventilated, with all ventilator settings remaining

Christine Watremez; Giuseppe Liistro; Marc deKock; Jean Roeseler; Thierry Clerbaux; Bruno Detry; Marc Reynaert; Pierre Gianello; Philippe Jolliet

2003-01-01

55

Reverse Mismatched Ventilation-Perfusion Pulmonary Imaging with Accumulation of Technetium99m-DTPA in a Mucous Plug in a Main Bronchus: A Case Report  

Microsoft Academic Search

The phenomenon of reverse mismatched ventilation-perfu- sion on pulmonary scintigraphy is a fairly common occur- rence. We present a patient who was experiencing decreas- ing oxygen saturation and had a reverse mismatched ventilation-perfusion imaging pattern associated with radio- tracer retention in a main bronchus. Technetium-99m-DTPA aerosol lung imaging showed tracer retention in the trachea and right main bronchus, absent ventilation

Wei-Jen Shih; Benedek Bognar

56

Significance of single ventilation/perfusion mismatches in krypton-81m/technetium-99m lung scintigraphy  

SciTech Connect

The significance of a single area of ventilation/perfusion (V/P) mismatch in lung scans performed on patients suspected of pulmonary embolism (PE) was evaluated. Ten of 20 patients with this scan finding were found to have PE. An intermediate probability of PE was found with segmental (71%) or subsegmental (45%) single V/P mismatches. Seven of 16 patients with a single V/P mismatch and without a matching radiographic opacity had PE. Three of the four patients who had a V/P mismatch and a matching radiographic opacity were found to have PE. Multiview ventilation imaging with 81mKr was found to have advantages for the evaluation of single V/P mismatches. Based on the data available at this time, a single V/P mismatch suggests an intermediate probability of PE.

Rosen, J.M.; Palestro, C.J.; Markowitz, D.; Alderson, P.O.

1986-03-01

57

Assessment of regional lung functional impairment with co-registered respiratory-gated ventilation\\/perfusion SPET-CT images: initial experiences  

Microsoft Academic Search

In this study, respiratory-gated ventilation and perfusion single-photon emission tomography (SPET) were used to define regional functional impairment and to obtain reliable co-registration with computed tomography (CT) images in various lung diseases. Using a triple-headed SPET unit and a physiological synchroniser, gated perfusion SPET was performed in a total of 78 patients with different pulmonary diseases, including metastatic nodules (

Kazuyoshi Suga; Kawakami Yasuhiko; Mohammed Zaki; Tomio Yamashita; Aska Seto; Tsuneo Matsumoto; Naofumi Matsunaga

2004-01-01

58

Focal hepatic activity during ventilation-perfusion scintigraphy due to systemic-portal shunt due to superior vena cava obstruction from histoplasmosis-induced fibrosing mediastinitis.  

PubMed

A 59-year-old woman with a history of fibrosing mediastinitis secondary to histoplasmosis diagnosed on mediastinoscopy presented with dyspnea. A ventilation-perfusion scan demonstrated decreased perfusion to the entire right lung. In addition, the perfusion images demonstrated focal abnormal activity in part of the liver. On computed tomography of the chest, there was significant soft tissue opacification in the mediastinum occluding the right pulmonary artery, with passage of the injected contrast via collateral vessels to the liver. The main collateral pathway was via the right internal thoracic vein and the umbilical vein. Pulmonary angiography confirmed complete occlusion of the right pulmonary artery. PMID:17710024

Mackie, Gavin C; Thomas, Aju; Greenspan, Bennett; Singh, Amolak

2007-09-01

59

PET lung ventilation/perfusion imaging using (68)Ga aerosol (Galligas) and (68)Ga-labeled macroaggregated albumin.  

PubMed

Pulmonary imaging using ventilation/perfusion (V/P) single-photon emission tomography (V/P scan) with Tc-99m-labeled radiotracers is a well-established diagnostic tool for clinically suspected pulmonary embolism (PE). Ga-68 aerosol (Galligas) and Ga-68-labeled macroaggregated albumin (MAA) are potential tracers for positron emission tomography (PET) lung V/P imaging and could display an advantage over conventional V/P scans in terms of sensitivity and specificity. After radiochemical and animal studies, the clinical applicability of Ga-68 aerosol (Galligas) and Ga-68-labeled MAA was investigated in an exploratory study in patients with clinical suspicion of PE. PET scans were acquired using a 16-slice Gemini TF positron emission tomography/computed tomography (PET/CT) scanner. The acquisition protocol included low-dose computed tomography (CT) for attenuation correction (AC). Dosimetry calculations and continuative phantom measurements were performed. Structural analyses showed no modification of the particles due to the labeling process. In addition, in vitro experiments showed stability of Ga-68 MAA in various media. As expected, Ga-68-labeled human serum albumin microspheres (HSAM) were completely retained in the lung of the animals. In clinical use, PET lung ventilation and perfusion imaging using Ga-68 aerosol (Galligas) and Ga-68-labeled MAA was successful in all cases. In one case a clinically suspected PE could be detected and verified. The administered activity of Ga-68 aerosol (Galligas) and Ga-68-labeled MAA may be reduced by more than 50%, resulting in comparable radiation exposure to conventional V/P scans. In conclusion, Ga-68 aerosol (Galligas) and Ga-68-labeled MAA are efficient substitutes for clinical use and could be an interesting alternative with high accuracy for lung V/P imaging with Tc-99m-labeled radiotracers, especially in times of Mo-99 shortages and increasing use and spread of PET/CT scanners and Ga-68 generators, respectively. PMID:22918772

Ament, S J; Maus, S; Reber, H; Buchholz, H G; Bausbacher, N; Brochhausen, C; Graf, F; Miederer, M; Schreckenberger, M

2013-01-01

60

Distinguishing Pulmonary Hypertension in Interstitial Lung Disease by Ventilation and Perfusion Defects Measured by Cardiopulmonary Exercise Testing.  

PubMed

Background: Pulmonary hypertension (PH) is common in interstitial lung disease (ILD). Since cardiopulmonary exercise testing (CPET) is useful in understanding the pathophysiology of respiratory disorders and can distinguish between ventilation and perfusion (V/Q) defects, it may have a role in the detection of PH in ILD. We evaluated whether CPET can detect PH through analysis of V/Q defects in ILD. Objectives: We aimed to use CPET to determine if there are changes in the ventilation and the activity pattern of mixed-expired carbon dioxide pressure (PECO2) and end-tidal carbon dioxide pressure (PetCO2) in ILD patients with and without PH. Methods: A retrospective chart review was done of all patients who received lung transplants at the Columbia University Medical Center between 2000 and 2011 with the diagnosis of ILD. CPETs were performed during the 2 years prior to transplantation; right heart catheterizations and pulmonary function tests were performed within 4 months of CPET. Results: The ILD patients with PH demonstrated significantly lower PetCO2 and PECO2 during certain levels of exercise with a distinctive activity pattern for PECO2/PetCO2. Conclusions: Evaluation of V/Q defects through the PECO2 and PetCO2 patterns on CPET in ILD patients can distinguish between patients with and without PH. PMID:23735701

Armstrong, Hilary F; Thirapatarapong, Wilawan; Dussault, Nicole E; Bartels, Matthew N

2013-05-28

61

Lung ventilation- and perfusion-weighted Fourier decomposition magnetic resonance imaging: in vivo validation with hyperpolarized 3He and dynamic contrast-enhanced MRI.  

PubMed

The purpose of this work was to validate ventilation-weighted (VW) and perfusion-weighted (QW) Fourier decomposition (FD) magnetic resonance imaging (MRI) with hyperpolarized (3)He MRI and dynamic contrast-enhanced perfusion (DCE) MRI in a controlled animal experiment. Three healthy pigs were studied on 1.5-T MR scanner. For FD MRI, the VW and QW images were obtained by postprocessing of time-resolved lung image sets. DCE acquisitions were performed immediately after contrast agent injection. (3)He MRI data were acquired following the administration of hyperpolarized helium and nitrogen mixture. After baseline MR scans, pulmonary embolism was artificially produced. FD MRI and DCE MRI perfusion measurements were repeated. Subsequently, atelectasis and air trapping were induced, which followed with FD MRI and (3)He MRI ventilation measurements. Distributions of signal intensities in healthy and pathologic lung tissue were compared by statistical analysis. Images acquired using FD, (3)He, and DCE MRI in all animals before the interventional procedure showed homogeneous ventilation and perfusion. Functional defects were detected by all MRI techniques at identical anatomical locations. Signal intensity in VW and QW images was significantly lower in pathological than in healthy lung parenchyma. The study has shown usefulness of FD MRI as an alternative, noninvasive, and easily implementable technique for the assessment of acute changes in lung function. PMID:22392633

Bauman, Grzegorz; Scholz, Alexander; Rivoire, Julien; Terekhov, Maxim; Friedrich, Janet; de Oliveira, Andre; Semmler, Wolfhard; Schreiber, Laura Maria; Puderbach, Michael

2012-03-05

62

Evaluation of residual functional lung volume on Tc-99m DTPA aerosol ventilation and Tc-99m MAA perfusion scintigraphy in primary ciliary dyskinesia (Kartagener syndrome).  

PubMed

Kartagener syndrome is diagnosed as sinusitis, bronchitis (bronchiectasis), and situs inversus by the clinical features. It is a subclass of primary ciliary dyskinesia (PCD) disease. A 12-year-old girl who had frequent upper and lower airway infections since birth, which was confirmed as Kartagener syndrome by HRCT imaging. We present the residual functional lung volume and mucociliary clearance findings seen on Tc-99m DTPA aerosol ventilation and Tc-99m MAA perfusion scintigraphy. PMID:19033804

Chen, Yu-Wen; Chang, Chin-Chuan; Lai, Yung-Chuang; Lu, Chia-Ying; Dai, Zen-Kong

2008-12-01

63

Role of spiral volumetric computed tomographic scanning in the assessment of patients with clinical suspicion of pulmonary embolism and an abnormal ventilation\\/perfusion lung scan  

Microsoft Academic Search

BACKGROUND: A study was carried out to evaluate the potential place of spiral volumetric computed tomography (SVCT) in the diagnostic strategy for pulmonary embolism. METHODS: In a prospective study 249 patients with clinical suspicion of pulmonary embolism were evaluated with various imaging techniques. In all patients a ventilation\\/perfusion (V\\/Q) scan was performed. Seventy seven patients with an abnormal V\\/Q scan

A. B. van Rossum; F. E. Treurniet; G. J. Kieft; S. J. Smith; R. Schepers-Bok

1996-01-01

64

Lung perfusion and ventilation during implantation of left ventricular assist device as a strategy to avoid postoperative pulmonary complications and right ventricular failure.  

PubMed

Right ventricular failure is a major contributor to increased morbidity and mortality in patients undergoing left ventricular assist device implantation. Cardiopulmonary bypass is associated with increased pulmonary ischaemia and pulmonary vascular resistance. Continuous pulmonary perfusion and ventilation represents an emerging strategy for pulmonary protection during cardiac surgery. We hypothesize that this technique may have a pivotal role in reducing postoperative right ventricular dysfunction in high-risk patients undergoing LVAD placement. PMID:23933964

Macedo, Francisco Igor B; Panos, Anthony L; Andreopoulos, Fotios M; Salerno, Tomas A; Pham, Si M

2013-08-09

65

Value of the ventilation/perfusion scan in acute pulmonary embolism: Results of the prospective investigation of pulmonary embolism diagnosis (PIOPED)  

SciTech Connect

To determine the sensitivities and specificities of ventilation/perfusion lung scans for acute pulmonary embolism, a random sample of 933 of 1,493 patients was studied prospectively. Nine hundred thirty-one underwent scintigraphy and 755 underwent pulmonary angiography; 251 (33%) of 755 demonstrated pulmonary embolism. Almost all patients with pulmonary embolism had abnormal scans of high, intermediate, or low probability, but so did most without pulmonary embolism. Of 116 patients with high-probability scans and definitive angiograms, 102 (88%) had pulmonary embolism, but only a minority with pulmonary embolism had high-probability scans. Of 322 with intermediate-probability scans and definitive angiograms, 105 (33%) had pulmonary embolism. Follow-up and angiography together suggest pulmonary embolism occurred among 12% of patients with low-probability scans. Clinical assessment combined with the ventilation/perfusion scan established the diagnosis or exclusion of pulmonary embolism only for a minority of patients--those with clear and concordant clinical and ventilation/perfusion scan findings.

Not Available

1990-05-23

66

Artificial perfusion of the ponto-medullary region of cats. A method for separation of central and peripheral effects of chemical stimulation of ventilation.  

PubMed

A technique is described by which the ponto-medullary region of anaesthetized cats is artificially perfused with their own blood in which the blood gas tensions are varied independently from gas exchange in the lung. Blood from a femoral artery is fed into a foamer and defoamer. After alteration of the blood gas tensions in this equilibrator it is pumped via a cannulated vertebral artery into the medulla oblongata, pons and cerebellum. In this way two separately perfused areas are obtained in which the blood gas tensions can be changed independently. The peripheral chemoreceptors are supplied with blood of the systemic circulation while the central chemoreceptors and respiratory integrating centres are artificially perfused. With this technique the contribution of the peripheral and central chemoreceptors to the total ventilation and their interaction can be assessed. In addition the method is also suitable for studying the effects of drugs on the central regulation of respiration and circulation. PMID:493755

Berkenbosch, A; Heeringa, J; Olievier, C N; Kruyt, E W

1979-08-01

67

Correlation of pulmonary 99mTc-DTPA ventilation and 99mTc-MAA perfusion scans with pulmonary function tests in asymptomatic asthmatic children.  

PubMed

Our objective was to examine and correlate 99mTc-diethylenetriaminopentaacetic acid (99mTc-DTPA) ventilation and 99mTc-macroaggregated albumin (99mTc-MAA) perfusion (V/Q) lung scans with spirometry in asymptomatic asthmatic children. We evaluated 89 subjects (age range, 6-15 years; mean age, 9.4 years), all with at least 70% predicted forced expiratory volume in 1 s (FEV(1)). There were four V/Q scan patterns: normal in 38 (42.7%), inhomogeneous ventilation in 11 (12.4%), matched defects in 25 (28.3%) and mismatched perfusion defects in 13 (14.6%). The maximal mid-expiratory flow rate (MMEF) of the normal scan group was significantly different from that in the other groups. The MMEF of the inhomogeneous group was significantly different from that in the matched defect group and the mismatched perfusion defect group. No other significant differences in spirometric indices were found. In two children with perfusion defects, pulmonary arteriograms demonstrated no obstructive lesions. In conclusion, lung scans provide diagnostic information in asymptomatic asthmatic children, even when they are uncooperative. Abnormal scans are common in these children and are significantly correlated with reduced MMEF (% predicted), reflecting small airway flow obstruction. The pathophysiology of V/Q defects in asymptomatic asthmatic children warrants further investigation. PMID:12813201

Dai, Z-K; Chen, Y-W; Hsu, J-H; Huang, M-S; Chou, S-H; Wu, J-R

2003-07-01

68

Relative accuracy of two diagnostic schemes for detection of pulmonary embolism by ventilation-perfusion scintigraphy  

SciTech Connect

Two diagnostic schemes for detection of pulmonary embolism by venilation-perfusion (V-P) scintigraphy were compared for relative accuracy by two groups of observers interpreting 70 V-P scintiscans. Observers in Group B, who used the criteria recently proposed by Biello et al., had a significantly smaller average number of ''indeterminate'' interpretations (41%) than did the observers in Group A (55%), who used a simpler scheme (p<0.05). In addition, Group B showed a slight improvement in positive predictive value without a deterioration in the negative predictive value compared with Group A.Along with this improvement in diagnostic performance, Group B achieved a significant reduction in interobserver variability compared with Group A for patients without pulmonary embolism (p<0.05). There was no significant difference in interobserver variability between the two groups for patients with pulmonary embolism. The diagnostic scheme introduced by Biello et al., represents a useful improvement for the diagnosis of pulmonary embolism by V-P imaging.

Carter, W.D. (Univ. of Michigan, Ann Arbor); Brady, T.M; Keyes, J.W. Jr.; Thrall, J.H.; Greenhouse, J.B.; Biello, D.R.; Siegel, B.A.; Alderson, P.O.; Brady, T.J.

1982-11-01

69

Low-probability ventilation-perfusion scintigrams: clinical outcomes in 99 patients  

SciTech Connect

To evaluate the reliability of low probability ventilation-perfursion (V-P) scintigrams in excluding pulmonary embolism (PE), the authors reviewed the clinical records of 99 consecutive patients whose V-P studies had been interpreted as indicative of a low probability of PE. None of the 99 patients were referred for pulmonary angiography. Seven of the hospitalized patients died during the index admission and seven additional hospitalized patients died 1-5 months after discharge from the hospital. None were thought clinically to have died as a result of PE, and autopsy disclosed no PE in two. Follow-up information was obtained for 69 surviving patients not treated with anticoagulants. None of these patients were thought clinically to have had PE during follow-up of a least 2 weeks duration (greater than 2 months in 93% and greater than 6 months in 75%). The results suggest that major short-term morbidity or death attributable to PE are quite infrequent in patients with low-probability V-P scintigrams.

Lee, M.E.; Biello, D.R.; Kumar, B.; Siegel, B.A.

1985-08-01

70

Ventilation\\/perfusion ratios and simultaneous dual-radionuclide single-photon emission tomography with krypton-81m and technetium-99m macroaggregated albumin  

Microsoft Academic Search

.   To date, there has been neither a good method to clarify the three-dimensional distribution of pulmonary ventilation\\/perfusion\\u000a (V.A\\/Q.) ratios, nor a convenient way to assess V.A\\/Q. inequality. The purpose of this study was to develop a functional image of pulmonary V.A\\/Q. ratios based on data acquired with simultaneous dual-radionuclide single-photon emission tomography (SPET) and to assess\\u000a V.A\\/Q. unevenness through

Y. Sando; T. Inoue; R. Nagai; K. Endo

1997-01-01

71

Radioaerosol ventilation imaging in ventilator-dependent patients. Technical considerations  

SciTech Connect

The differentiation of pulmonary embolism (PE) from regional ventilatory abnormalities accompanied by reduced perfusion requires contemporary perfusion and ventilation studies. Distinguishing these conditions in ventilator-dependent patients is aided by administering a Tc-99m aerosol to characterize regional ventilation, and by performing a conventional Tc-99m MAA perfusion study. The technique uses a simple in-house constructed apparatus. Simple photographic techniques suffice, but computer subtraction of perfusion from the combined perfusion-ventilation image renders interpretation easier if aerosol administration follows perfusion imaging. Multiple defects can be examined in a single study. Excluding normal or near-normal perfusion studies, PE was thought to be present in eight of 16 patients after perfusion imaging alone, but in only one of eight after added aerosol imaging. Angiography confirmed the diagnosis in that patient. Of the eight patients who had abnormal perfusion but were thought unlikely to have PE from the perfusion study alone, two had normal ventilation, and subsequently were shown to have PE by angiography. Because angiography was only performed on patients who were thought to have a high probability of PE on sequential perfusion-ventilation imaging, the true incidence of PE may have been higher. Aerosol ventilation imaging is a useful adjunct to perfusion imaging in patients on ventilators. It requires an efficient delivery system, particularly if aerosol administration follows perfusion imaging, as it does in this study.

Vezina, W.; Chamberlain, M.; Vinitski, S.; King, M.; Nicholson, R.; Morgan, W.K.

1985-11-01

72

The Bedside Investigation of Pulmonary Embolism Diagnosis Study A Double-blind Randomized Controlled Trial Comparing Combinations of 3 Bedside Tests vs Ventilation-Perfusion Scan for the Initial Investigation of Suspected Pulmonary Embolism  

Microsoft Academic Search

Background: We sought to determine whether using combinations of 3 bedside tests (7-variable clinical model, non-enzyme-linked immunosorbent assay D-dimer test, and alveolar dead-space fraction) to exclude pulmonary embolism (PE) before diagnostic imaging was as safe as a standard strategy of starting with ventilation- perfusion (V\\/Q) scan. Methods: In this double-blind, randomized, con- trolled equivalency trial, patients were randomized to ini-

Marc A. Rodger; Christopher N. Bredeson; Gwynne Jones; Pasteur Rasuli; Francois Raymond; Anne Marie Clement; Alan Karovitch; Helene Brunette; Dimitri Makropoulos; Mark Reardon; Ian Stiell; Rama Nair; Philip S. Wells

2006-01-01

73

An evaluation of preoperative and postoperative ventilation and perfusion lung scintigraphy in the screening for pulmonary embolism after elective orthopedic surgery  

SciTech Connect

One hundred two patients undergoing elective knee or hip arthroplasty were studied with radionuclide ventilation scans (V) and perfusion scans (Q) preoperatively (preop) and postoperatively (postop) to assess their relative value in the diagnosis of asymptomatic pulmonary embolism (PE) after orthopedic surgery. Postop Q were read in combination with preop V and Q and postop V using prospective investigation of pulmonary embolism diagnosis (PIOPED) criteria. Of 25 postop Q interpreted as either high or intermediate probability for PE, preop Q were judged useful in 96%; the postop V were useful in 78%; and the preop V were not helpful in any of the cases. Of 63 postop Q interpreted as low probability, preop Q were useful in 74%; the postop V were useful in only 33%; and the preop V were useful in only one case. When postop Q were read as normal (14 cases), none of the three auxiliary studies were found to be useful. Overall, postop V were more helpful than preop Q in only 2%, and preop V contributed significantly in only 1%. This experience suggests that preop Q alone is the most useful adjunct to the postop Q in the postoperative evaluation for PE. The authors conclude that to screen for asymptomatic PE after elective orthopedic surgery, preop Q should be performed in all cases, preop V are not necessary, and postop V need be performed only if a baseline preop Q is not available.

Keenan, A.M.; Palevsky, H.I.; Steinberg, M.E.; Hartman, K.M.; Alavi, A.; Lotke, P.A. (Univ. of Pennsylvania, Philadelphia (USA))

1991-01-01

74

Imbalance rotating machine balancing  

Microsoft Academic Search

Imbalance analysis is essential in the rotating machine. However, some problems still remain in the aspects of computational efficiency and accuracy. In the present paper, a new method was proposed for estimating the mass imbalance of a rotating shaft by using the vibration signals. This is a new method for the detection of a mass imbalance and its phase position.

Hua Su; Han-Soo Choi; Kil T. Chong

2005-01-01

75

[Choice of optimal ventilation maintenance].  

PubMed

Twenty-nine angiosurgical patients with disordered ventilation-perfusion correlations were examined. Effects of CMV (controlled mechanical ventilation) + PEEP (positive end expiratory pressure) and IRV (inverse ratio of ventilation) on gas exchange and hemodynamics of the lungs were studied. Gas exchange improved in all patients, but sooner in the CMV + PEEP group. CI increase was more pronounced in the IRV group. PMID:12221881

Amerov, D B; Kazennov, V V; Likhvantsev, V V; Shishkin, M N; Morozova, M E

76

The effects of pulse-delivered inhaled nitric oxide on arterial oxygenation, ventilation-perfusion distribution and plasma endothelin-1 concentration in laterally recumbent isoflurane-anaesthetized horses.  

PubMed

OBJECTIVES: Anaesthetized horses commonly become hypoxaemic due to ventilation/perfusion (V·A/Q·) mismatch and increased pulmonary shunt fraction (Qs·/Qt·). Pulse-delivered inhaled nitric oxide may improve oxygenation but may increase plasma concentration of the potent vasoconstrictor, endothelin-1 (ET-1). Objectives: Study 1) compare arterial oxygen concentration (PaO2 ) and saturation (SaO2 ), calculated Qs·/Qt· and ET-1 concentration; and Study 2) assess V·A/Q· matching and measured Qs·/Qt· in isoflurane-anaesthetized horses in left lateral recumbency receiving pulse-delivered inhaled nitric oxide (PiNO group) or inhalant gas only (C group). STUDY DESIGN: Prospective research trial. ANIMALS: Ten Healthy adult Standardbred horses. Two horses were anaesthestized in both groups in a random cross-over design with >4 weeks between studies. METHODS: Study 1) Cardiopulmonary data including PaO2 , SaO2 , Qs·/Qt· and ET-1 concentration were measured or calculated prior to and at various points during PiNO administration in 6PiNO and 6C horses. Two-way repeated measures anova with Bonferroni significant difference test was used for data analysis with p < 0.05 considered significant. Study 2) V·A/Q· matching and Qs·/Qt· were determined using the multiple inert gas elimination technique in 3 horses. Data were collected after 60 minutes of anaesthesia without PiNO (baseline) and 15 minutes after PiNO was pulsed during the first 30%, and then the first 60%, of inspiration. Data were descriptive only. RESULTS: Study 1) PaO2 and SaO2 were higher and calculated Qs·/Qt· was lower in the PiNO group than the C group at most time points. ET-1 was not different over time or between groups. Study 2) V·A/Q· matching and measured Qs·/Qt· were improved from baseline in all horses but PiNO60% provided no improvement when compared to PiNO30%. CONCLUSIONS AND CLINICAL RELEVANCE: PiNO delivered in the initial portion of the inspiration effectively relieves hypoxaemia in anaesthetized horses by improving V·A/Q· matching and decreasing Qs·/Qt· without affecting ET-1. PMID:23601237

Grubb, Tamara; Frendin, Jan Hm; Edner, Anna; Funkquist, Pia; Hedenstierna, Göran; Nyman, Görel

2013-04-20

77

Lung Ventilation/Perfusion Scan  

MedlinePLUS

... Show What Are the Risks Links Related Topics Pulmonary Embolism Arrhythmia Deep Vein Thrombosis Cough Related Media Videos ... used to help diagnose or rule out a pulmonary embolism (PULL-mun-ary EM-bo-lizm), or PE. ...

78

Imbalance rotating machine balancing  

NASA Astrophysics Data System (ADS)

Imbalance analysis is essential in the rotating machine. However, some problems still remain in the aspects of computational efficiency and accuracy. In the present paper, a new method was proposed for estimating the mass imbalance of a rotating shaft by using the vibration signals. This is a new method for the detection of a mass imbalance and its phase position. Based on the signal processing with FFT, an estimator was designed to detect the mass of imbalance. And an improved Lissajous diagram was also introduced with statistical analysis, which make it possible to compute the phase position of the mass imbalance efficiently and arranged at a certain location of the shaft. The proposed method was demonstrated and validated through several test examples.

Su, Hua; Choi, Han-Soo; Chong, Kil T.

2005-12-01

79

Where Is the Imbalance?  

ERIC Educational Resources Information Center

|For many researchers, the concept of a power imbalance is central to the understanding of bullying, and its presence in the bully-victim relationship is a prerequisite condition that needs to be fulfilled before bullying is deemed to have taken place. Despite the concept's central importance in many definitions of bullying, the nature of the…

Chan, John H. F.

2009-01-01

80

Administration of hydrogen sulfide via extracorporeal membrane lung ventilation in sheep with partial cardiopulmonary bypass perfusion: a proof of concept study on metabolic and vasomotor effects  

PubMed Central

Introduction Although inhalation of 80 parts per million (ppm) of hydrogen sulfide (H2S) reduces metabolism in mice, doses higher than 200 ppm of H2S were required to depress metabolism in rats. We therefore hypothesized that higher concentrations of H2S are required to reduce metabolism in larger mammals and humans. To avoid the potential pulmonary toxicity of H2S inhalation at high concentrations, we investigated whether administering H2S via ventilation of an extracorporeal membrane lung (ECML) would provide means to manipulate the metabolic rate in sheep. Methods A partial venoarterial cardiopulmonary bypass was established in anesthetized, ventilated (fraction of inspired oxygen = 0.5) sheep. The ECML was alternately ventilated with air or air containing 100, 200, or 300 ppm H2S for intervals of 1 hour. Metabolic rate was estimated on the basis of total CO2 production (V?CO2) and O2 consumption (V?O2). Continuous hemodynamic monitoring was performed via indwelling femoral and pulmonary artery catheters. Results V?CO2, V?O2, and cardiac output ranged within normal physiological limits when the ECML was ventilated with air and did not change after administration of up to 300 ppm H2S. Administration of 100, 200 and 300 ppm H2S increased pulmonary vascular resistance by 46, 52 and 141 dyn·s/cm5, respectively (all P ? 0.05 for air vs. 100, 200 and 300 ppm H2S, respectively), and mean pulmonary artery pressure by 4 mmHg (P ? 0.05), 3 mmHg (n.s.) and 11 mmHg (P ? 0.05), respectively, without changing pulmonary capillary wedge pressure or cardiac output. Exposure to 300 ppm H2S decreased systemic vascular resistance from 1,561 ± 553 to 870 ± 138 dyn·s/cm5 (P ? 0.05) and mean arterial pressure from 121 ± 15 mmHg to 66 ± 11 mmHg (P ? 0.05). In addition, exposure to 300 ppm H2S impaired arterial oxygenation (PaO2 114 ± 36 mmHg with air vs. 83 ± 23 mmHg with H2S; P ? 0.05). Conclusions Administration of up to 300 ppm H2S via ventilation of an extracorporeal membrane lung does not reduce V?CO2 and V?O2, but causes dose-dependent pulmonary vasoconstriction and systemic vasodilation. These results suggest that administration of high concentrations of H2S in venoarterial cardiopulmonary bypass circulation does not reduce metabolism in anesthetized sheep but confers systemic and pulmonary vasomotor effects.

2011-01-01

81

Muscle imbalance among elite athletes  

Microsoft Academic Search

BackgroundPrevious research in team sports, such as football and cricket, has found muscle imbalances in the lumbo-pelvic region, especially in muscles involved in joint stability and protection. It is thought that these muscle imbalances occur as a result of the specific requirements of the sport. However, this pattern of muscular imbalance may not be isolated to team sports and may

M Franettovich; J Hides; M D Mendis; H Littleworth

2011-01-01

82

The isolated perfused lung.  

PubMed Central

The unique nonrespiratory functions of the lungs have become more apparent in recent years. The isolated perfused lung model offers many advantages over other methods for the study of pulmonary metabolism, xenobiotic disposition and the influence of interactions among agents of different physical forms. Detailed descriptions of the experimental preparation are elements in evaluating and comparing data from various sources but these are frequently neglected. A discussion and critique of the following elements are provided in this review in order to elucidate the typical problems one might encounter in evaluating data: perfusate type, perfusion method, construction materials, ventilation method, temperature control, surgical procedure, microbiological contamination and evaluation criteria of the preparation. Examples are given where the IPL method has been applied and suggestions are made for future research efforts.

Niemeier, R W

1984-01-01

83

Applications in spinal imbalance.  

PubMed

The pelvis may be seen as a single vertebra, between the spine and the femurs. The anatomy of this pelvic vertebra has changed with the evolution of species, notably with the transition to bipedalism, with the consequent appearance of lumbar lordosis. The lumbosacral angle, almost non-existent in other mammals, is at its greatest in humans. Pelvic and spinal radiological parameters reflect the sagittal balance of the spine in bipedal humanity. Applications in the management of spinal imbalance are numerous. Arthrogenic or degenerative kyphosis is the stereotypic example of spinal aging. Postoperative flat back following spine surgery is hard to prevent. Scoliosis surgery in adults should now take greater account of the patient's individual sagittal balance, by analyzing the pelvic and spinal parameters. The extent of arthrodeses performed during adolescence to manage idiopathic scoliosis may also induce problems of balance in adulthood if these elements are not taken into account. PMID:20447889

Husson, J-L; Mallet, J-F; Parent, H; Cavagna, R; Vital, J-M; Blamoutier, A; Violas, P

2010-05-01

84

Ventilation abnormalities associated with pulmonary embolism  

SciTech Connect

A retrospective analysis of 2035 lung images performed over approximately 5 years revealed abnormal ventilation coexisting with pulmonary embolism in 18 patients. Matching ventilation perfusion defects may be associated with pulmonary embolism without infarction. In patients with a high clinical suspicion of acute pulmonary embolism and matching V/Q abnormalities, an angiogram may be necessary to definitely exclude the diagnosis.

Sandler, M.S.; Velchik, M.G.; Alavi, A.

1988-06-01

85

Krypton-81m ventilation scanning: acute respiratory disease  

SciTech Connect

From experience with 700 patients undergoing ventilation and perfusion lung scanning with krypton-81m/technetium-99m technique, 34 patients suffering from nonembolic acute respiratory disease were selected for review. In 16 patients with pneumonia, all had defects of ventilation corresponding to, or larger than, the radiologic consolidation. In 13 patients there was some preservation of perfusion in the consolidated region. In two of the three patients with matched defects, the pneumonia was of long standing. In seven patients with collapse or atelectasis and in 11 patients with acute reversible bronchial obstruction and normal volume lungs, a similar pattern or ventillation and perfusion was observed.

Lavender, J.P. (Royal Postgraduate Medical School, London, England); Irving, H.; Armstrong, J.D. II

1981-02-01

86

Radioaerosol Ventilation System 'Radio Vent': Technical Considerations, Construction and Operation,  

National Technical Information Service (NTIS)

Lung imaging with a radioactive tracer is a noninvasive technique and is performed to show distribution of ventilation (air) and perfusion (blood) in the lungs. (99m) Tc based system has received considerable attention due to ideal decay characteristics o...

M. M. Ishfaq R. A. Khan H. M. A. Karim

1987-01-01

87

Ventilation Model  

SciTech Connect

The purpose of this analysis and model report (AMR) for the Ventilation Model is to analyze the effects of pre-closure continuous ventilation in the Engineered Barrier System (EBS) emplacement drifts and provide heat removal data to support EBS design. It will also provide input data (initial conditions, and time varying boundary conditions) for the EBS post-closure performance assessment and the EBS Water Distribution and Removal Process Model. The objective of the analysis is to develop, describe, and apply calculation methods and models that can be used to predict thermal conditions within emplacement drifts under forced ventilation during the pre-closure period. The scope of this analysis includes: (1) Provide a general description of effects and heat transfer process of emplacement drift ventilation. (2) Develop a modeling approach to simulate the impacts of pre-closure ventilation on the thermal conditions in emplacement drifts. (3) Identify and document inputs to be used for modeling emplacement ventilation. (4) Perform calculations of temperatures and heat removal in the emplacement drift. (5) Address general considerations of the effect of water/moisture removal by ventilation on the repository thermal conditions. The numerical modeling in this document will be limited to heat-only modeling and calculations. Only a preliminary assessment of the heat/moisture ventilation effects and modeling method will be performed in this revision. Modeling of moisture effects on heat removal and emplacement drift temperature may be performed in the future.

H. Yang

1999-11-04

88

Liquid Ventilation  

PubMed Central

Mammals have lungs to breathe air and they have no gills to breath liquids. When the surface tension at the air-liquid interface of the lung increases, as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen, as the inert carrier of oxygen and carbon dioxide offers a number of theoretical advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. The potential for multiple clinical applications for liquid-assisted ventilation will be clarified and optimized in future.

Tawfic, Qutaiba A.; Kausalya, Rajini

2011-01-01

89

Repeat perfusion imaging may differentiate airways obstruction from pulomonary embolic disease: report of two cases  

SciTech Connect

Two cases are presented in which patients with obstructive lung disease were considered to have a pulmonary embolism (PE). Emergency lung perfusion scans supported the diagnosis of PE in both cases. However, rapid resolution of the symptoms and perfusion defects by repeat ventilation-perfusion scanning at 24 hr suggested that PE was unlikely. In selected cases of wheezing patients, repeat perfusion scans may obviate the need for pulmonary angiography. The authors report two cases in which repeat perfusion scans almost normalized by 24 hr. Review of the literature indicates that the rate of resolution of perfusion defects would have been much slower had pulmonary embolism occurred.

Greenspon, L.W.; LaManna, M.M.; Dhand, S.

1987-06-01

90

Noninvasive ventilation after intubation and mechanical ventilation  

Microsoft Academic Search

Noninvasive ventilation after intubation and mechanical ventilation. M. Ferrer, O. Bernadich, S. Nava, A. Torres. #ERS Journals Ltd 2002. ABSTRACT: Patients with chronic airflow obstruction who are difficult to wean from mechanical ventilation are at increased risk of intubation-associated complications and mortality because of prolonged invasive mechanical ventilation. Noninvasive positive pressure ventilation may revert most of the pathophysiological mechanisms associated

M. Ferrer; O. Bernadich; S. Nava; A. Torres

2002-01-01

91

Nasal ventilation.  

PubMed Central

Nasal intermittent positive pressure ventilation is likely to have an increasing role in the management of acute ventilatory failure, weaning, and chronic ventilatory problems. Further improvements in ventilator and mask design will be seen. Appropriate application is likely to reduce both mortality and admissions to intensive care, while domiciliary use can improve life expectancy and/or quality of life in chronic ventilatory disorders. As with any new technique, enthusiasm should not outweigh clear outcome information, and possible new indications should always be subject to careful assessment. Images Figure 2

Simonds, A. K.

1998-01-01

92

Control of resting ventilation rate in grasshoppers  

PubMed

We examined the effect of extracellular acid-base status and tracheal gas levels on the ventilation rate of resting Romalea guttata and Schistocerca americana grasshoppers. We manipulated haemolymph pH and [HCO3-] within normal physiological ranges using injections of HCl, NaOH, NaHCO3 and NaCl into the haemocoel. In contrast to terrestrial vertebrates, there was no evidence that extracellular acidification increases ventilation rate in grasshoppers. Elevation of haemolymph bicarbonate levels (by NaHCO3 injection) increased ventilation rate, while depression of haemolymph bicarbonate levels (HCl injection) had no effect. Injection of NaHCO3 also increased tracheal PCO2, suggesting that the effect of the NaHCO3 injection might be mediated by a sensitivity of the ventilatory system to tracheal gases. We tested for effects of tracheal gases on ventilation rate by independently manipulating tracheal PCO2 and PO2 using tracheal perfusions. Ventilation rate was positively correlated with tracheal PCO2 and negatively correlated with tracheal PO2. Increasing tracheal PO2 above normal resting levels or decreasing tracheal PCO2 below normal levels decreased ventilation rate. We conclude that quiescent grasshoppers regulate tracheal PCO2 and PO2 by varying ventilation rate and that both PCO2 and PO2 in the trachea stimulate ventilation in normal, resting grasshoppers. PMID:9317989

Gulinson; Harrison

1996-01-01

93

Energy Imbalance Markets (Fact Sheet)  

SciTech Connect

The anticipated increase in variable renewable generation, such as wind and solar power, over the next several years has raised concerns about how system operators will maintain balance between electricity production and demand in the Western Interconnection, especially in its smaller balancing authority areas (BAAs). Given renewable portfolio standards in the West, it is possible that more than 50 gigawatts of wind capacity will be installed by 2020. Significant quantities of solar generation are likely to be added as well. Meanwhile, uncertainties about future load growth and challenges siting new transmission and generation resources may add additional stresses on the Western Interconnection of the future. One proposed method of addressing these challenges is an energy imbalance market (EIM). An EIM is a means of supplying and dispatching electricity to balance fluctuations in generation and load. It aggregates the variability of generation and load over multiple balancing areas (BAs).

Not Available

2012-09-01

94

Earth's Energy Imbalance and Implications  

NASA Astrophysics Data System (ADS)

Improving observations of ocean heat content show that Earth is absorbing more energy from the Sun than it is radiating to space as heat, even during the recent solar minimum. We update our analysis of Earth's observed energy imbalance through 2011 and compare this with climate simulations. Observed global surface temperature change and ocean heat gain together constrain the net climate forcing, implying existence of a large negative forcing by human-made aerosols. Continued failure to quantify the specific origins of this large forcing is untenable, as knowledge of changing aerosol effects is needed to understand future climate change. We discuss implications of the trend of observed sea level rise in recent years, and its consistency with reported ice melt rates and ocean thermal expansion.

Hansen, J.; von Schuckmann, K.; Sato, M.; Kharecha, P.

2012-04-01

95

The US, China, and global imbalances  

Microsoft Academic Search

Although there have been surplus and deficit nations in the world for some time, the magnitude of the so-called global imbalances in the 2000s provided the macroeconomic backdrop to the worst financial crisis in nearly a century. The key players are the United States and China, but the global macroeconomic imbalances involve many other emerging economies. Although the genesis of

Linda Yueh

2010-01-01

96

Improvement in accuracy of transcutaneous measurement of oxygen with resumption of spontaneous ventilation in mechanically ventilated patients after off pump coronary artery bypass procedure: a prospective study  

Microsoft Academic Search

Introduction  Transcutaneous measurement of gases depends on the degree of skin perfusion. Mechanical ventilation causes alteration in the\\u000a peripheral perfusion. The aim of this prospective observational study was to assess change in the accuracy of interchangeability\\u000a of arterial blood gases with those obtained transcutaneously at various phases of mechanical ventilation such as controlled\\u000a mandatory, synchronized intermittent mandatory, continuous positive airway pressure

Murali Chakravarthy; Sandeep Narayan; Raghav Govindarajan; Vivek Jawali

2009-01-01

97

Earth's energy imbalance and implications  

NASA Astrophysics Data System (ADS)

Improving observations of ocean heat content show that Earth is absorbing more energy from the sun than it is radiating to space as heat, even during the recent solar minimum. The inferred planetary energy imbalance, 0.59 ± 0.15 W m-2 during the 6-year period 2005-2010, confirms the dominant role of the human-made greenhouse effect in driving global climate change. Observed surface temperature change and ocean heat gain together constrain the net climate forcing and ocean mixing rates. We conclude that most climate models mix heat too efficiently into the deep ocean and as a result underestimate the negative forcing by human-made aerosols. Aerosol climate forcing today is inferred to be -1.6 ± 0.3 W m-2, implying substantial aerosol indirect climate forcing via cloud changes. Continued failure to quantify the specific origins of this large forcing is untenable, as knowledge of changing aerosol effects is needed to understand future climate change. We conclude that recent slowdown of ocean heat uptake was caused by a delayed rebound effect from Mount Pinatubo aerosols and a deep prolonged solar minimum. Observed sea level rise during the Argo float era is readily accounted for by ice melt and ocean thermal expansion, but the ascendency of ice melt leads us to anticipate acceleration of the rate of sea level rise this decade. Humanity is potentially vulnerable to global temperature change, as discussed in the Intergovernmental Panel on Climate Change (IPCC, 2001, 2007) reports and by innumerable authors. Although climate change is driven by many climate forcing agents and the climate system also exhibits unforced (chaotic) variability, it is now widely agreed that the strong global warming trend of recent decades is caused predominantly by human-made changes of atmospheric composition (IPCC, 2007). The basic physics underlying this global warming, the greenhouse effect, is simple. An increase of gases such as CO2 makes the atmosphere more opaque at infrared wavelengths. This added opacity causes the planet's heat radiation to space to arise from higher, colder levels in the atmosphere, thus reducing emission of heat energy to space. The temporary imbalance between the energy absorbed from the sun and heat emission to space, causes the planet to warm until planetary energy balance is restored. The planetary energy imbalance caused by a change of atmospheric composition defines a climate forcing. Climate sensitivity, the eventual global temperature change per unit forcing, is known with good accuracy from Earth's paleoclimate history. However, two fundamental uncertainties limit our ability to predict global temperature change on decadal time scales. First, although climate forcing by human-made greenhouse gases (GHGs) is known accurately, climate forcing caused by changing human-made aerosols is practically unmeasured. Aerosols are fine particles suspended in the air, such as dust, sulfates, and black soot (Ramanathan et al., 2001). Aerosol climate forcing is complex, because aerosols both reflect solar radiation to space (a cooling effect) and absorb solar radiation (a warming effect). In addition, atmospheric aerosols can alter cloud cover and cloud properties. Therefore, precise composition-specific measurements of aerosols and their effects on clouds are needed to assess the aerosol role in climate change. Second, the rate at which Earth's surface temperature approaches a new equilibrium in response to a climate forcing depends on how efficiently heat perturbations are mixed into the deeper ocean. Ocean mixing is complex and not necessarily simulated well by climate models. Empirical data on ocean heat uptake are improving rapidly, but still suffer limitations. We summarize current understanding of this basic physics of global warming and note observations needed to narrow uncertainties. Appropriate measurements can quantify the major factors driving climate change, reveal how much additional global warming is already in the pipeline, and help define the reduction of climate forcing needed to stabilize climate.

Hansen, J.; Sato, M.; Kharecha, P.; von Schuckmann, K.

2011-09-01

98

Ventilated Supercavities  

NASA Astrophysics Data System (ADS)

Drag reduction and/or speed augmentation of marine vehicles by means of supercavitation is a topic of great interest. During the initial launch of a supercavitating vehicle, ventilation is required to supply an artificial cavity until conditions at which a natural supercavity can be sustained are reached. A study has been carried out to determine various aspects of the flow physics of a supercavitating vehicle at Saint Anthony Falls Laboratory. During the present experimental work, the ventilated supercavity formed behind a sharp-edged disk was investigated using several configurations. Results regarding cavity shape and closure, as well as ventilation requirements versus cavitation number and Froude number are presented. In addition, effects related to flow choking in a water tunnel test section are discussed. Results obtained are similar in character to previously reported results, but differ significantly in measured values. An attempt was made to correlate results from water tunnel experiments to open flows, where there are no effects of flow choking. Supercavitation parameters, especially the minimum attainable cavitation number are found to be strongly affected by tunnel blockage and Froude number.

Kawakami, Ellison; Arndt, Roger

2011-11-01

99

Ventilated Supercavities  

NASA Astrophysics Data System (ADS)

The topic of supercavitation is of considerable interest to drag reduction and/or speed augmentation in marine vehicles. Supercavitating vehicles need to be supplied with an artificial cavity through ventilation until they accelerate to conditions at which a natural supercavity can be sustained. A study has been carried out in the high-speed water tunnel at St. Anthony Falls Laboratory to investigate some aspects of the flow physics of such a supercavitating vehicle. During the present experimental work, the ventilated supercavity formed behind a sharp-edged disk was investigated utilizing several different configurations. Results regarding cavity shape, cavity closure and ventilation requirements versus cavitation number and Froude number are presented. Additionally, effects related to flow choking in a water tunnel test section are discussed. Results obtained are similar in character to previously reported results, but differ significantly in measured values. Cavity shape, particularly aft of the maximum cavity diameter, is found to be a strong function of the model support scheme chosen.

Kawakami, Ellison; Arndt, Roger

2009-11-01

100

Assessment of Changes in Distribution of Lung Perfusion by Electrical Impedance Tomography  

Microsoft Academic Search

Background: Electrical impedance tomography (EIT) is able to detect variations in regional lung electrical impedance associated with changes in both air and blood content and potentially capable of assessing regional ventilation-perfusion relationships. However, regional lung perfusion is difficult to determine because the impedance changes synchronous with the heart rate are of very small amplitude. Objectives: The aim of our study

Inéz Frerichs; Sven Pulletz; Gunnar Elke; Florian Reifferscheid; Dirk Schädler; Jens Scholz; Norbert Weiler

2009-01-01

101

Kitchen ventilation  

SciTech Connect

Kitchen ventilation is a subject that has not received the attention that has been given to more glamorous HVAC and R topics. Consequently, its theoretical and technical development has not advanced like these topics. However, a group has been working within the ASHRAE Technical Committee (TC) and Task Group (TG) framework to correct this situation. The group is TG5.KV and it achieved TG status last year after starting as an informal group and then a sub-committee of TC9.8. One of its efforts has been to write a Handbook chapter, which will appear in the 1995 ASHRAE Handbook -- Applications. This article is a survey of that chapter.

Kelso, R.M. [Univ. of Tennessee, Knoxville, TN (United States). College of Architecture; Rousseau, C. [Newcomb and Boyd Consulting Engineers, Atlanta, GA (United States)

1995-09-01

102

Estimation of Lung Ventilation  

NASA Astrophysics Data System (ADS)

Since the primary function of the lung is gas exchange, ventilation can be interpreted as an index of lung function in addition to perfusion. Injury and disease processes can alter lung function on a global and/or a local level. MDCT can be used to acquire multiple static breath-hold CT images of the lung taken at different lung volumes, or with proper respiratory control, 4DCT images of the lung reconstructed at different respiratory phases. Image registration can be applied to this data to estimate a deformation field that transforms the lung from one volume configuration to the other. This deformation field can be analyzed to estimate local lung tissue expansion, calculate voxel-by-voxel intensity change, and make biomechanical measurements. The physiologic significance of the registration-based measures of respiratory function can be established by comparing to more conventional measurements, such as nuclear medicine or contrast wash-in/wash-out studies with CT or MR. An important emerging application of these methods is the detection of pulmonary function change in subjects undergoing radiation therapy (RT) for lung cancer. During RT, treatment is commonly limited to sub-therapeutic doses due to unintended toxicity to normal lung tissue. Measurement of pulmonary function may be useful as a planning tool during RT planning, may be useful for tracking the progression of toxicity to nearby normal tissue during RT, and can be used to evaluate the effectiveness of a treatment post-therapy. This chapter reviews the basic measures to estimate regional ventilation from image registration of CT images, the comparison of them to the existing golden standard and the application in radiation therapy.

Ding, Kai; Cao, Kunlin; Du, Kaifang; Amelon, Ryan; Christensen, Gary E.; Raghavan, Madhavan; Reinhardt, Joseph M.

103

FATE OF INHALED NITROGEN DIOXIDE IN ISOLATED PERFUSED RAT LUNG  

EPA Science Inventory

The fate of inhaled NO2 was studied with isolated perfused rat lungs. The isolated lungs were exposed to 5 ppm NO2 for 90 min at a ventilation rate of 45 ml/min. The NO2 exposure had no adverse effects on the lungs as judged from their weights, glucose uptake, or lactate producti...

104

Ventilation Effectiveness - A Guide to Efficient Ventilation.  

National Technical Information Service (NTIS)

A two-zone mixing model describes the concept(s) of and defines the effectiveness of ventilation. Multiroom aspects and procedures for measuring ventilation effectiveness are dealt with. The simple two-zone model, experimentally verified by laboratory tes...

E. Skaaret H. M. Mathisen

1983-01-01

105

Gas exchange and intrapulmonary distribution of ventilation during continuous-flow ventilation  

SciTech Connect

In 12 anesthetized paralyzed dogs, pulmonary gas exchange and intrapulmonary inspired gas distribution were compared between continuous-flow ventilation (CFV) and conventional mechanical ventilation (CMV). Nine dogs were studied while they were lying supine, and three dogs were studied while they were lying prone. A single-lumen catheter for tracheal insufflation and a double-lumen catheter for bilateral endobronchial insufflation (inspired O2 fraction = 0.4; inspired minute ventilation = 1.7 +/- 0.3 (SD) 1.kg-1.min-1) were evaluated. Intrapulmonary gas distribution was assessed from regional 133Xe clearances. In dogs lying supine, CO2 elimination was more efficient with endobronchial insufflation than with tracheal insufflation, but the alveolar-arterial O2 partial pressure difference was larger during CFV than during CMV, regardless of the type of insufflation. By contrast, endobronchial insufflation maintained both arterial PCO2 and alveolar-arterial O2 partial pressure difference at significantly lower levels in dogs lying prone than in dogs lying supine. In dogs lying supine, the dependent lung was preferentially ventilated during CMV but not during CFV. In dogs lying prone, gas distribution was uniform with both modes of ventilation. The alveolar-arterial O2 partial pressure difference during CFV in dogs lying supine was negatively correlated with the reduced ventilation of the dependent lung, which suggests that increased ventilation-perfusion mismatching was responsible for the increase in alveolar-arterial O2 partial pressure difference. The more efficient oxygenation during CFV in dogs lying prone suggests a more efficient matching of ventilation to perfusion, presumably because the distribution of blood flow is also nearly uniform.

Vettermann, J.; Brusasco, V.; Rehder, K.

1988-05-01

106

Order imbalance and individual stock returns: Theory and evidence  

Microsoft Academic Search

This paper studies the relation between order imbalances and daily returns of individual stocks. Our tests are motivated by a model which considers how market makers dynamically accommodate autocorrelated imbalances emanating from large traders who optimally choose to split their orders. Price pressures caused by autocorrelated imbalances cause a positive relation between lagged imbalances and returns, which reverses sign after

Tarun Chordia; Avanidhar Subrahmanyam

2004-01-01

107

Redox imbalance and biochemical changes in cancer.  

PubMed

For this article, we explore a hypothesis involving the possible role of reduction/oxidation (redox) state in cancer. We hypothesize that many modifications in cellular macromolecules, observed in cancer progression, may be caused by redox imbalance. Recent biochemical data suggest that human prostate cancer cell lines show a redox imbalance (oxidizing) compared with benign primary prostate epithelial cells; the degree of oxidation varied with aggressive behavior of each cell line. Our recent data suggest that human breast cancer tissues show a redox imbalance (reducing) compared with benign adjacent breast tissues. Accumulating data summarized in this article suggest that redox imbalance may regulate gene expression and alter protein stability by posttranslational modifications, in turn modulating existing cellular programs. Despite significant improvements in cancer therapeutics, resistance occurs, and redox imbalance may play a role in this process. Studies show that some cancer therapeutic agents increase generation of reactive oxygen/nitrogen species and antioxidant enzymes, which may alter total antioxidant capacity, cause cellular adaptation, and result in reduced effectiveness of treatment modalities. Approaches involving modulations of intra- and extracellular redox states, in combination with other therapies, may lead to new treatment options, especially for patients who are resistant to standard treatments. Cancer Res; 73(20); 6118-23. ©2013 AACR. PMID:23878188

Jorgenson, Tonia C; Zhong, Weixiong; Oberley, Terry D

2013-07-22

108

End-tidal carbon dioxide as a measure of arterial carbon dioxide during intermittent mandatory ventilation  

Microsoft Academic Search

To determine if end-tidal carbon dioxide tension (PetCO2) is a clinically reliable indicator of arterial carbon dioxide tension (PaCO2) under conditions of heterogeneous tidal volumes and ventilation-perfusion inequality, we examined the expiratory gases of\\u000a 25 postcardiotomy patients being weaned from ventilator support with intermittent mandatory ventilation. Using a computerized\\u000a system that automatically sampled airway flow, pressure, and expired carbon dioxide

Matthew B. Weinger; John E. Britain

1987-01-01

109

VENTILATION NEEDS DURING CONSTRUCTION  

SciTech Connect

The purpose of this analysis is to determine ventilation needs during construction and development of the subsurface repository and develop systems to satisfy those needs. For this analysis, construction is defined as pre-emplacement excavation and development is excavation that takes place simultaneously with emplacement. The three options presented in the ''Overall Development and Emplacement Ventilation Systems'' analysis (Reference 5.5) for development ventilation will be applied to construction ventilation in this analysis as well as adding new and updated ventilation factors to each option for both construction and development. The objective of this analysis is to develop a preferred ventilation system to support License Application Design. The scope of this analysis includes: (1) Description of ventilation conditions; (2) Ventilation factors (fire hazards, dust control, construction logistics, and monitoring and control systems); (3) Local ventilation alternatives; (4) Global ventilation options; and (5) Evaluation of options.

C.R. Gorrell

1998-07-23

110

Ventilation above Closing Volume Reduces Pulmonary Vascular Resistance Hysteresis  

Microsoft Academic Search

The aim of this study was to determine the relationship of pulmonary vascular resistance (PVR) hys- teresis and lung volume, with special attention to the effects of ventilation around closing volume (CV). Isolated, blood-perfused canine left lower lung lobes (LLL) were incrementally inflated and de- flated. Airway and pulmonary artery pressures (PAP) were recorded after each stepwise volume change. Constant

KEVIN M. CREAMER; LARYSSA L. M C CLOUD; LYLE E. FISHER; INA C. EHRHART

1998-01-01

111

Cryptic telomere imbalance: A 15-year update  

Microsoft Academic Search

It has been 15 years since we proposed that assays of telomere integrity might reveal cryptic translocations and deletions as a significant cause of mental retardation (MR) in patients with normal G-banded karyotypes. Development of unique genomic probes adjacent to the subtelomeric repeats of each chromosome arm allowed multiplex FISH analyses that confirmed such cryptic telomeric imbalances in 3-6% of

David H. Ledbetter; Christa Lese Martin

2007-01-01

112

Dynamic class imbalance learning for incremental LPSVM.  

PubMed

Linear Proximal Support Vector Machines (LPSVMs), like decision trees, classic SVM, etc. are originally not equipped to handle drifting data streams that exhibit high and varying degrees of class imbalance. For online classification of data streams with imbalanced class distribution, we propose a dynamic class imbalance learning (DCIL) approach to incremental LPSVM (IncLPSVM) modeling. In doing so, we simplify a computationally non-renewable weighted LPSVM to several core matrices multiplying two simple weight coefficients. When data addition and/or retirement occurs, the proposed DCIL-IncLPSVM(1) accommodates newly presented class imbalance by a simple matrix and coefficient updating, meanwhile ensures no discriminative information lost throughout the learning process. Experiments on benchmark datasets indicate that the proposed DCIL-IncLPSVM outperforms classic IncSVM and IncLPSVM in terms of F-measure and G-mean metrics. Moreover, our application to online face membership authentication shows that the proposed DCIL-IncLPSVM remains effective in the presence of highly dynamic class imbalance, which usually poses serious problems to previous approaches. PMID:23584135

Pang, Shaoning; Zhu, Lei; Chen, Gang; Sarrafzadeh, Abdolhossein; Ban, Tao; Inoue, Daisuke

2013-03-14

113

Diabetic Autonomic Imbalance and Glycemic Variability  

PubMed Central

Diabetic autonomic neural imbalance is a severe complication of long-term diabetes patients and may progress to diabetic autonomic neuropathy (DAN). The prevalence of DAN is reported to be between 20 and 70%, depending on the studies. The pathogenesis of DAN remains unresolved. However, emerging evidence suggests that glycemic variability (GV) may be associated with autonomic imbalance in patients with both type 1 and type 2 diabetes. As symptoms are initially weak and uncharacteristic, the condition often remains undiagnosed until late manifestations present themselves. Predominant symptoms may include nausea, vomiting, gastroparesis, involuntary diarrhea, postural hypotension, voiding difficulties, and sexual dysfunction. Analyzing the patterns of heart rate variability carries the potential for detection of autonomic imbalance in the subclinical and asymptomatic stages. In this context, GV may affect the sympathovagal balance by increasing oxidative stress and proinflammatory cytokines. Establishing a GV risk profile could therefore be important in determining risk factors in diabetes patients. This review addresses the issues above and in particular the possible association between diabetic autonomic imbalance and GV.

Fleischer, Jesper

2012-01-01

114

Demographic transition and demographic imbalance in India  

Microsoft Academic Search

In the coming decades, there will be growing demographic disparity in India and, like economic disparity, this should be a matter of serious concern for our planners and policy-makers. This demographic disparity leading to demographic imbalance may cause considerable social turbulence and may even pose a threat to political stability. Demographers must look far beyond demographic statistics and anticipate the

Ashish Bose

115

Compensation of IQ imbalance in OFDM systems  

Microsoft Academic Search

Today a lot of attention is spent on developing inexpensive OFDM receivers. Especially, zero-IF receivers are very appealing, because they avoid costly IF filters. However, this implies IQ demodulation at RF, which therefore cannot be done digitally and thus introduces IQ mismatch. Unfortunately, OFDM is very sensitive to receiver IQ imbalance. Therefore, we developed a new compensation scheme to combat

Jan Tubbax; B. Come; L. Van der Perre; L. Deneire; S. Donnay; M. Engels

2003-01-01

116

A South African perspective on global imbalances  

Microsoft Academic Search

Financial inflows into South African financial markets have resumed in 2009 and gained momentum in 2010, largely as a result of low interest rates and an oversupply of liquidity in advanced economies. As an emerging-market country with a current-account defi cit, South Africa is to some extent reliant on these inflows to fund its own external imbalance. However, fi nancial

G. Marcus

2011-01-01

117

Pathophysiology of inner ear fluid imbalance.  

PubMed

Maintenance of homeostasis of inner ear fluids and biochemical integrity of inner ear tissue are essential for proper functioning of the auditory and vestibular end organs. Although various regulatory mechanisms exist in a different portion of the labyrinth, the inner ear is known to respond to systemic challenges. The association of Meniere's syndrome with an imbalance of inner ear fluid homeostasis has been hypothesized for the past century. Among many factors, the effects of hormonal imbalance on inner ear fluid composition and inner ear function have however scarcely been studied. The purpose of this study was to explore the relationship between the autonomic nervous system and inner ear function and possible mechanisms of functional disturbances in an experimental condition. An infusion of supraphysiologic amounts of epinephrine, a stress related hormone, resulted in an elevation of osmolality in serum and perilymph. Furthermore, the infusion of epinephrine resulted in elevation of threshold, prolongation of latency, and depression of amplitude in the compound action potential of the auditory nerve. These findings were most marked at high frequencies. We hypothesized that the epinephrine-induced hearing loss was brought about by an increase in perilymphatic osmolality, as well as by the ionic imbalance caused by the osmotic gradient. Since emotional stress has been implicated as a mechanism of inducing a Meniere's attack, evaluation of the relationship between the autonomic system and cochlear function may contribute to the understanding of possible mechanisms of inner ear dysfunction caused by hormonal imbalances. PMID:1843177

Juhn, S K; Ikeda, K; Morizono, T; Murphy, M

1991-01-01

118

[Mechanical ventilation of acute lung injury].  

PubMed

Acute lung injury (ALI) is of paramount importance for modern intensive care since it is one of the most frequent conditions necessitating admission to an ICU. ALI is characterised by severe life threatening hypoxemia which is based on ventilation perfusion mismatching within the lung. This is mostly resulting from atelectasis formation due to primary or secondary inflammation of lung tissue. Many studies showed that this inflammatory process is not restricted to the respiratory system but might result in non pulmonary organ failure and hemodynamic compromise as well. Mechanical ventilation is considered the hallmark treatment for ALI patients aimed to recruit lung tissue and thereby reverse hypoxemia without causing additional lung injury potentially resulting from overdistention or cycling collapse during expiration. Scientific evidence shows us that prevention of ventilator induced lung injury by protective ventilation with reduced tidal volumes is resulting in better clinical outcomes. Moreover, different technologies and adjunctive therapies have been suggested based on their pathophysiology. All these treatment options will be summarized in this article. Given the clear evidence for protective ventilation and bearing in mind that clinical application of this easy concept is still not widespread we will focus on this aspect. PMID:17455139

Kuhlen, R; Dembinski, R

2007-04-01

119

Single perfusion defect and pulmonary embolism: Angiographic correlation  

SciTech Connect

One hundred and thirty-three ventilation-perfusion scans (V-P) with angiographic correlation were retrospectively reviewed to evaluate the frequency of pulmonary emboli (PE) in single perfusion defects (SPD), regardless of ventilation or radiographic findings. By angiography, 15 of 30 SPD cases had PE. Demographic data and clinical presentation were similar for PE and non-PE patients. However, 9 out of 15 patients with PE had recent surgery compared to none of the non-PE patients. SPD were seen in areas of ventilation and chest x-ray abnormalities in 12 of 15 PE and 11 of 19 non-PE cases. Size of the actual lesion was underestimated by scintigraphy in most cases. In 7 of 15 PE cases, the perfusion defect was larger than the corresponding ventilation abnormality. Most SPD were located at the bases. Twelve of 15 SPD in the PE group were at the posterior basilar segment. In the appropriate clinical setting, SPD carries at least a moderate probability for PE. When the clinical suspicion is high, a pulmonary angiography will be needed to confirm the diagnosis.

Catania, T.A.; Caride, V.J. (Hospital of Saint Raphael, New Haven, CT (USA))

1990-03-01

120

Metformin attenuates ventilator-induced lung injury  

PubMed Central

Introduction Diabetic patients may develop acute lung injury less often than non-diabetics; a fact that could be partially ascribed to the usage of antidiabetic drugs, including metformin. Metformin exhibits pleiotropic properties which make it potentially beneficial against lung injury. We hypothesized that pretreatment with metformin preserves alveolar capillary permeability and, thus, prevents ventilator-induced lung injury. Methods Twenty-four rabbits were randomly assigned to pretreatment with metformin (250 mg/Kg body weight/day per os) or no medication for two days. Explanted lungs were perfused at constant flow rate (300 mL/min) and ventilated with injurious (peak airway pressure 23 cmH2O, tidal volume ?17 mL/Kg) or protective (peak airway pressure 11 cmH2O, tidal volume ?7 mL/Kg) settings for 1 hour. Alveolar capillary permeability was assessed by ultrafiltration coefficient, total protein concentration in bronchoalveolar lavage fluid (BALF) and angiotensin-converting enzyme (ACE) activity in BALF. Results High-pressure ventilation of the ex-vivo lung preparation resulted in increased microvascular permeability, edema formation and microhemorrhage compared to protective ventilation. Compared to no medication, pretreatment with metformin was associated with a 2.9-fold reduction in ultrafiltration coefficient, a 2.5-fold reduction in pulmonary edema formation, lower protein concentration in BALF, lower ACE activity in BALF, and fewer histological lesions upon challenge of the lung preparation with injurious ventilation. In contrast, no differences regarding pulmonary artery pressure and BALF total cell number were noted. Administration of metformin did not impact on outcomes of lungs subjected to protective ventilation. Conclusions Pretreatment with metformin preserves alveolar capillary permeability and, thus, decreases the severity of ventilator-induced lung injury in this model.

2012-01-01

121

Ventilation Strategies for Different Climates.  

National Technical Information Service (NTIS)

Until recently, residential ventilation in the United States has been provided by infiltration. In this report we compare natural ventilation (ventilation by infiltration) with several mechanical ventilation strategies and examine the overall energy consu...

H. E. Feustel M. P. Modera A. H. Rosenfeld

1987-01-01

122

Learning about ventilators  

MedlinePLUS

... mouth or anopening through their neck into the trachea (windpipe). A ventilator may also be referred to ... a tube that connects the ventilator to the trachea). Suctioning is a word you will hear a ...

123

Periumbilical uptake of Tc-99m MAA on lung perfusion scanning in a patient with superior vena cava obstruction.  

PubMed

A 25-year-old woman with severe parenchymal lung disease of unknown etiology and existing for more than a decade was referred for ventilation-perfusion scintigraphy because of suspicion of pulmonary embolism. Both ventilation and perfusion images showed, apart from perfusion defects from her severe lung disease, a left apical pneumothorax and signs of recurrent pneumonia of the left lower lobe. Noteworthy was the periumbilical uptake of the Tc-99m macroaggregated albumin (MAA). Her medical history revealed iatrogenic superior vena cava (SVC) obstruction. In this case, the main collateral pathway of portosystemic shunting is probably, after recanalization of the left umbilical vein, a network of smaller paraumbilical veins. PMID:16550019

Balink, H; Nabers, J

2006-04-01

124

Mechanical ventilation for the home  

Microsoft Academic Search

A ventilation system gives occupants control over a home`s air change rate and thermal control. This article discussed the option available today for good mechanical ventilation. Topic covered include ventilation codes; types of ventilation; ventilation approaches (fan types, heat recovery ventilation); avoid backdrafting; meeting outdoor air requirements; sizing fans; ducts and terminal devices; timers and other controls. 3 tabs.

1996-01-01

125

Propranolol for neurocardiogenic syncope with sympathoadrenal imbalance  

Microsoft Academic Search

Background: Neurocardiogenic syncope with sympathoadrenal imbalance (SAI) is characterized by loss of consciousness preceded by a disproportionately greater increase in plasma epinephrine than norepinephrine. In SAI, forearm vascular resistance decreases, probably because of skeletal muscle vasodilation from beta-2 adrenoceptor activation by epinephrine. We hypothesized that a non-selective beta blocker, propranolol, would prevent syncope associated with SAI, by attenuating beta-2-receptor-mediated vasodilation.Methods:

B. Eldadah; S. Pechnik; C. Holmes; D. S. Goldstein

2005-01-01

126

HVAC (heating, ventilation, air conditioning) literature in Japan: A critical review  

Microsoft Academic Search

Japanese businessmen in the heating, ventilation, air conditioning, and refrigeration (HVACandR) industry consider the monitoring of technical and market developments in the United States to be a normal part of their business. In contrast, efforts by US businessmen to monitor Japanese HVAC and R developments are poorly developed. To begin to redress this imbalance, this report establishes the groundwork for

Hane

1988-01-01

127

Patient-ventilator asynchrony during assisted mechanical ventilation  

Microsoft Academic Search

Objective  The incidence, pathophysiology, and consequences of patient-ventilator asynchrony are poorly known. We assessed the incidence of patient-ventilator asynchrony during assisted mechanical ventilation and we identified associated factors.Methods  Sixty-two consecutive patients requiring mechanical ventilation for more than 24?h were included prospectively as soon as they triggered all ventilator breaths: assist-control ventilation (ACV) in 11 and pressure-support ventilation (PSV) in 51.Measurements  Gross asynchrony detected

Arnaud W. Thille; Pablo Rodriguez; Belen Cabello; François Lellouche; Laurent Brochard

2006-01-01

128

Effect of spontaneous breathing on ventilator-induced lung injury in mechanically ventilated healthy rabbits: a randomized, controlled, experimental study  

PubMed Central

Introduction Ventilator-induced lung injury (VILI), one of the most serious complications of mechanical ventilation (MV), can impact patients' clinical prognoses. Compared to control ventilation, preserving spontaneous breathing can improve many physiological features in ventilated patients, such as gas distribution, cardiac performance, and ventilation-perfusion matching. However, the effect of spontaneous breathing on VILI is unknown. The goal of this study was to compare the effects of spontaneous breathing and control ventilation on lung injury in mechanically-ventilated healthy rabbits. Methods Sixteen healthy New Zealand white rabbits were randomly placed into a spontaneous breathing group (SB Group) and a control ventilation group (CV Group). Both groups were ventilated for eight hours using biphasic positive airway pressure (BIPAP) with similar ventilator parameters: inspiration pressure (PI) resulting in a tidal volume (VT) of 10 to 15 ml/kg, inspiratory-to-expiratory ratio of 1:1, positive end-expiration pressure (PEEP) of 2 cmH2O, and FiO2 of 0.5. Inflammatory markers in blood serum, lung homogenates and bronchoalveolar lavage fluid (BALF), total protein levels in BALF, mRNA expressions of selected cytokines in lung tissue, and lung injury histopathology scores were determined. Results Animals remained hemodynamically stable throughout the entire experiment. After eight hours of MV, compared to the CV Group, the SB Group had lower PaCO2 values and ratios of dead space to tidal volume, and higher lung compliance. The levels of cytokines in blood serum and BALF in both groups were similar, but spontaneous breathing led to significantly lower cytokine mRNA expressions in lung tissues and lower lung injury histological scores. Conclusions Preserving spontaneous breathing can not only improve ventilatory function, but can also attenuate selected markers of VILI in the mechanically-ventilated healthy lung.

2011-01-01

129

Scintigraphy-ventilatio\\/perfusion scanning and imaging of the embolus  

Microsoft Academic Search

Summary Purpose: This is a review of data on ventilation\\/perfusion (V\\/Q) imaging obtained in the collaborative study, Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED). Special emphasis is given to data obtained subsequent to the main PIOPED publication. New criteria for the interpretation of V\\/Q scans are based on data obtained by retrospective evaluation of the data from PIOPED. Background: PIOPED

P. D. Stein

2000-01-01

130

Hydrolysis of triglycerides in the isolated perfused rat lung  

Microsoft Academic Search

The purpose of this study was to investigate the hydrolysis of saturated and unsaturated triglycerides by lung lipoprotein\\u000a lipase and to measure the incorporation of triglyceride fatty acids into lung tissue lipids. Lipolytic activity was studied\\u000a in the isolated ventilated rat lung, perfused for 100 min in a recycling system with Krebs Ringer bicarbonate containing bovine\\u000a serum albumin, 5.6 mM

Suzanne K. Compton; Margit Hamosh; Paul Hamosh

1982-01-01

131

[Complications of mechanical ventilation].  

PubMed

Mechanical ventilation of the lungs, as an important therapeutic measure, cannot be avoided in critically ill patients. However, when machines take over some of vital functions there is always a risk of complications and accidents. Complications associated with mechanical ventilation can be divided into:1) airway-associated complications; 2) complications in the response of patients to mechanical ventilation; and 3) complications related to the patient's response to the device for mechanical ventilation. Complications of artificial airway may be related to intubation and extubation or the endotracheal tube. Complications of mechanical ventilation, which arise because of the patient's response to mechanical ventilation, may primarily cause significant side effects to the lungs. During the last two decades it was concluded that mechanical ventilation can worsen or cause acute lung injury. Mechanical ventilation may increase the alveolar/capillary permeability by overdistension of the lungs (volutrauma), it can exacerbate lung damage due to the recruitment/derecruitment of collapsed alveoli (atelectrauma) and may cause subtle damages due to the activation of inflammatory processes (biotrauma). Complications caused by mechanical ventilation, beside those involving the lungs, can also have significant effects on other organs and organic systems, and can be a significant factor contributing to the increase of morbidity and mortality in critically ill of mechanically ventilated patients. Complications are fortunately rare and do not occur in every patient, but due to their seriousness and severity they require extensive knowledge, experience and responsibility by healthcare workers. PMID:22070009

Draškovi?, Biljana; Raki?, Goran

132

Perfusion scintigraphy in the diagnosis of pulmonary embolism: a self-assessment quiz  

SciTech Connect

The authors present ten case reports with lung scintigrams in a format suitable for a self-assessment quiz. The first seven cases include perfusion scintigrams and the final diagnosis was established by postmortem examination. The last three studies include ventilation images (using nebulized /sup 99m/Tc tin colloid) and the final diagnosis established by nonradionuclide studies. The authors believe this quiz demonstrates the necessity for ventilation studies when using lung scintigraphy for a positive diagnosis.

Egermayer, P.; Rutland, M.D.

1982-07-01

133

A review on electrical impedance tomography for pulmonary perfusion imaging.  

PubMed

Although electrical impedance tomography (EIT) for ventilation monitoring is on the verge of clinical trials, pulmonary perfusion imaging with EIT remains a challenge, especially in spontaneously breathing subjects. In anticipation of more research on this subject, we believe a thorough review is called for. In this paper, findings related to the physiological origins and electrical characteristics of this signal are summarized, highlighting properties that are particularly relevant to EIT. The perfusion impedance change signal is significantly smaller in amplitude compared with the changes due to ventilation. Therefore, the hardware used for this purpose must be more sensitive and more resilient to noise. In previous works, some signal- or image-processing methods have been required to separate these two signals. Three different techniques are reviewed in this paper, including the ECG-gating method, frequency-domain-filtering-based methods and a principal-component-analysis-based method. In addition, we review a number of experimental studies on both human and animal subjects that employed EIT for perfusion imaging, with promising results in the diagnosis of pulmonary embolism (PE) and pulmonary arterial hypertension as well as other potential applications. In our opinion, PE is most likely to become the main focus for perfusion EIT in the future, especially for heavily instrumented patients in the intensive care unit (ICU). PMID:22532291

Nguyen, D T; Jin, C; Thiagalingam, A; McEwan, A L

2012-04-24

134

Non-invasive ventilation  

Microsoft Academic Search

Non-invasive ventilation (NIV) refers to the delivery of mechanical ventilation to the lungs using techniques that do not\\u000a require an endotracheal airway. Essentially, there are two modalities: continuous positive airway pressure (CPAP) and pressure\\u000a support ventilation (NIPSV). In acute pulmonary edema (APE) both modalities have shown a faster improvement in gas exchange\\u000a and physiologic parameters with respect to conventional oxygen

Josep Masip

2007-01-01

135

Lung scan perfusion defects limited to matching pleural effusions: low probability of pulmonary embolism  

SciTech Connect

Patients with a new pleural effusion are often sent for a ventilation-perfusion scan to exclude a pulmonary embolism. This retrospective study assessed the probability of pulmonary embolism when a pleural effusion and a perfusion defect of similar size are the only significant imaging abnormalities. In 451 reports of patients who were scanned for suspected pulmonary embolism, 53 had perfusion defects secondary to pleural effusion without other significant perfusion defects. Using pulmonary angiography, venography, analysis of pleural fluid, clinical course, and other radiographic and laboratory studies to establish the final diagnosis, only two patients had documented venous thrombotic disease: one had pulmonary emboli, the other thrombophlebitis. Lung scans having significant perfusion defects limited to pleural effusions and matching them in size have a low probability for pulmonary embolism.

Bedont, R.A.; Datz, F.L.

1985-12-01

136

The perfused rat lung as a model for studies on the formation of surfactant and the effect of Ambroxol on this process  

Microsoft Academic Search

The isolated perfused rat lung was used as a model to investigate the synthesis of surfactant phospholipids from various radioactive\\u000a precursors and the effect of Ambroxol, a bronchial secretolyticum, on this process. Lungs were ventilated and perfused for\\u000a periods up to 5 h without detectable development of pulmonary edema. The lungs remained metabolically stable during the entire\\u000a period of perfusion.

M. Post; J. J. Batenburg; E. A. J. M. Schuurmans; V. Oldenborg; A. J. van der Molen; L. M. G. van Golde

1983-01-01

137

Multifamily Ventilation Retrofit Strategies  

SciTech Connect

In multifamily buildings, central ventilation systems often have poor performance, overventilating some portions of the building (causing excess energy use), while simultaneously underventilating other portions (causing diminished indoor air quality). BSC and Innova Services Corporation performed a series of field tests at a mid-rise test building undergoing a major energy audit and retrofit, which included ventilation system upgrades.

Ueno, K.; Lstiburek, J.; Bergey, D.

2012-12-01

138

Thailand ventilation comfort chart  

Microsoft Academic Search

The paper presents a ventilation comfort chart that has been developed under Thailand climate and using Thai volunteers. 183 male and 105 female college-age subjects were exposed to different thermal conditions in order to investigate the effect of air velocity on thermal comfort in ventilated “non-conditioned” spaces. To this end, commercial electric fans were used to control the air velocity

Joseph Khedari; Nuparb Yamtraipat; Naris Pratintong; Jongjit Hirunlabh

2000-01-01

139

Realtime mine ventilation simulation  

SciTech Connect

This paper describes the development of a Windows based, interactive mine ventilation simulation software program at the Waste Isolation Pilot Plant (WIPP). To enhance the operation of the underground ventilation system, Westinghouse Electric Corporation developed the program called WIPPVENT. While WIPPVENT includes most of the functions of the commercially available simulation program VNETPC and uses the same subroutine to calculate airflow distributions, the user interface has been completely rewritten as a Windows application with screen graphics. WIPPVENT is designed to interact with WIPP ventilation monitoring systems through the sitewise Central monitoring System. Data can be continuously collected from the Underground Ventilation Remote Monitoring and Control System (e.g., air quantity and differential pressure) and the Mine Weather Stations (psychrometric data). Furthermore, WIPPVENT incorporates regulator characteristic curves specific to the site. The program utilizes this data to create and continuously update a REAL-TIME ventilation model. This paper discusses the design, key features, and interactive capabilities of WIPPVENT.

McDaniel, K.H. [Westinghouse Electric Corp., Carlsbad, NM (United States). Waste Isolation Div.; Wallace, K.G. Jr. [Mine Ventilation Services, Inc., Fresno, CA (United States)

1997-04-01

140

Clinical Impact of Proximal Autosomal Imbalances  

PubMed Central

Centromere-near gain of copy number can be induced by intra- or inter-chromosomal rearrangements or by the presence of a small supernumerary marker chromosome (sSMC). Interestingly, partial trisomy to hexasomy of euchromatic material may be present in clinically healthy or affected individuals, depending on origin and size of chromosomal material involved. Here we report the known minimal sizes of all centromere-near, i.e., proximal auto-somal regions in humans, which are tolerated; over 100 Mb of coding DNA are comprised in these regions. Additionally, we have summarized the typical symptoms for nine proximal autosomal regions including genes obviously sensitive to copy numbers. Overall, studying the carriers of specific chromosomal imbalances using genomics-based medicine, combined with single cell analysis can provide the genotype-phenotype correlations and can also give hints where copy-number-sensitive genes are located in the human genome.

Hamid, AB; Weise, A; Voigt, M; Bucksch, M; Kosyakova, N; Liehr, T; Klein, E

2012-01-01

141

Hindlimb unloading elicits anhedonia and sympathovagal imbalance.  

PubMed

The hindlimb-unloaded (HU) rat model elicits cardiovascular deconditioning and simulates the physiological adaptations to microgravity or prolonged bed rest in humans. Although psychological deficits have been documented following bed rest and spaceflight in humans, few studies have explored the psychological effects of cardiovascular deconditioning in animal models. Given the bidirectional link established between cardiac autonomic imbalance and psychological depression in both humans and in animal models, we hypothesized that hindlimb unloading would elicit an alteration in sympathovagal tone and behavioral indexes of psychological depression. Male, Sprague-Dawley rats confined to 14 days of HU displayed anhedonia (a core feature of human depression) compared with casted control (CC) animals evidenced by reduced sucrose preference (CC: 81 +/- 2.9% baseline vs. HU: 58 +/- 4.5% baseline) and reduced (rightward shift) operant responding for rewarding electrical brain stimulation (CC: 4.4 +/- 0.3 muA vs. 7.3 +/- 1.0 muA). Cardiac autonomic blockade revealed elevated sympathetic [CC: -54 +/- 14.1 change in (Delta) beats/min vs. HU: -118 +/- 7.6 Delta beats/min] and reduced parasympathetic (CC: 45 +/- 11.8 Delta beats/min vs. HU: 8 +/- 7.3 Delta beats/min) cardiac tone in HU rats. Heart rate variability was reduced (CC: 10 +/- 1.4 ms vs. HU: 7 +/- 0.7 ms), and spectral analysis of blood pressure indicated loss of total, low-, and high-frequency power, consistent with attenuated baroreflex function. These data indicate that cardiovascular deconditioning results in sympathovagal imbalance and behavioral signs consistent with psychological depression. These findings further elucidate the pathophysiological link between cardiovascular diseases and affective disorders. PMID:18635876

Moffitt, Julia A; Grippo, Angela J; Beltz, Terry G; Johnson, Alan Kim

2008-07-17

142

Autonomic Imbalance and Borderline States of Thyrotoxicosis  

PubMed Central

Primary thyrotoxicosis may be regarded as having two main components—thyroid overactivity or dysfunction, and instability of the autonomic nervous system. Clinical observation suggests that the proportion of each component varies in individual cases. Results of treatment show that the larger the thyroid element the greater is the benefit of thyroidectomy or X-ray therapy, and the fewer the subsequent residual signs. When nervous instability predominates less relief is obtained by surgery or X-rays, and symptoms may be little changed or even made worse by the addition of hypothyroidism. Cases in which nervous instability predominates, with minimal thyroid dysfunction, have been termed “autonomic imbalance”, “neurocirculatory asthenia”, or “Basedow's disease with no thyrotoxicosis”. Thirteen such cases are described, all of which were females, with average age of 32 years. 9 had enlarged thyroids, 11 complained of palpitations, and 8 of excessive sweating. The basal metabolic rate, estimated in 8 cases, did not exceed +10%. There was some loss of weight in 6 cases, but in none was the appetite increased. The average diurnal pulse-rate did not exceed 95 and sleeping pulse was significantly lower. X-rays of heart, taken in 6 cases, were normal. Psychological troubles in 6 cases. Three cases treated by X-ray therapy and I surgically with no benefit. Remaining 10 cases treated medically with improvement. The group is ill-defined and requires further investigation of cause and treatment. The recognition of autonomic imbalance is important in order to avoid useless thyroidectomy or X-ray therapy, and encourage more extended use of psychotherapy. Investigation of its cause may yield information of value in the ætiological problem of thyrotoxicosis.

Martin, Laurence

1939-01-01

143

Cerebral perfusion imaging.  

PubMed

Recent advances are allowing computed tomography (CT) and magnetic resonance imaging (MRI) to add diagnostic information derived from microscopic-scale brain structure, pathology, and physiology to the gross pathologic information that has been the core of brain imaging diagnosis since the 1980s. Physiologic imaging with MR perfusion weighted imaging has joined MR diffusion imaging as an essential components of stroke and brain tumor MRI. At the same time, the volume scanning revolution in CT technology has dramatically decreased the radiation doses required for CT perfusion imaging by allowing routine simultaneous CT perfusion and noninvasive dynamic bone subtracted CT angiography (CTA) without a significant increase in radiation dose over conventional head CT-CTA alone. Although ongoing research and clinical trials is needed to define more precisely how these techniques can best be exploited to improve clinical care and patient outcomes, in the acute stroke and subarachnoid hemorrhage populations the radiation risk associated with CT perfusion imaging is negligible and the physiologic information promises significant patient safety benefits. PMID:23361488

Hochberg, Aaron R; Young, Geoffrey S

2013-01-29

144

Slow imbalance relaxation and thermoelectric transport in graphene  

Microsoft Academic Search

We compute the electronic component (kappa) of the thermal conductivity and the thermoelectric power (alpha) of monolayer graphene, within the hydrodynamic regime, taking into account the slow rate of carrier population imbalance relaxation. Interband electron-hole generation and recombination processes are inefficient due to the non-decaying nature of the relativistic energy spectrum. As a result, a population imbalance of the conduction

Igor Aleiner; Matthew Foster

2009-01-01

145

Novel method for indirect sensing of hard disk drive imbalance  

Microsoft Academic Search

At present, hard disk drives (HDD) are balanced using external balancing machine after all components of HDD are assembled. Therefore, company's throughput is limited by number of available balancing machines. Besides, imbalance is measured only once after assembly, and for this reason there is no possibility to measure if there is any change in imbalance of HDD during its operation.

Branislav Hredzak; Guoxiao Guo

2004-01-01

146

New Method for Sensorless Measurement of Hard Disk Drives Imbalance  

Microsoft Academic Search

At present, hard disk drives (HDDs) are balanced using external balancing machine after all the components of the HDD are assembled. Therefore, company's throughput is limited by a number of available balancing machines. Besides, an imbalance is measured only once after assembly, and for this reason, there is no possibility to measure if there is any change in imbalance of

Branislav Hredzak; Guoxiao Guo; Jingliang Zhang

2006-01-01

147

Adjustment of Global Imbalances and Its Impact on China's Economy  

Microsoft Academic Search

The present paper discusses ways of adjusting the imbalances of the global economy and its impact on China's economy. The analysis in the paper shows that the cut of US fiscal deficits and the appreciation of the currencies of East Asia, including China's RMB, are necessary for a smooth adjustment of the global imbalances. The adjustments will have a positive

Jianhuai Shi

2006-01-01

148

Global imbalances and a trade-finance-nexus  

Microsoft Academic Search

Purpose – This paper inquires into the root causes of global imbalances from an international trade perspective. The purpose of the paper is to establish a conceptual framework that links financial market governance, international trade and financial market integration, and to derive implications for the global financial crisis. Design\\/methodology\\/approach – In order to analyze global imbalances, the paper draws on

Andreas Kern; Christian Fahrholz

2009-01-01

149

Street youths’ control imbalance and soft and hard drug use  

Microsoft Academic Search

In his control balance theory Charles Tittle maintained that under favorable conditions unbalanced control ratios will lead to different forms of deviance. The type of deviance chosen is argued to depend on the degree of the control imbalance and the desirability the offense presents as a method of altering the imbalance. Utilizing a sample of homeless street youth this study

Stephen W. Baron

2010-01-01

150

Global imbalances and prospects for the world economy  

Microsoft Academic Search

Most explanations of the current economic and financial crisis focus on its financial causes. Often missing in these explanations is a discussion of how the seeds of the crisis were sown by economic policies in major countries that fostered the growth of global imbalances during the 2000s. Moreover, just as these imbalances created the current crisis, exactly how they are

Steven Dunaway

2009-01-01

151

Conventional mechanical ventilation.  

PubMed

Mechanical ventilation has become a very common and well-accepted practice in modern intensive care units. The use of the mechanical ventilator has progressed from being a support system during surgery and for acutely ill patients to being used in both moderate and long-term life support in patients with inadequate ventilation. The sophistication of modern ventilators and the ability of trained respiratory therapists and nursing personnel have permitted this technology to explode. This is occurring at a time when there are still many controversies about the relative benefits and modes of action of conventional ventilation. As newer techniques are developed, it is mandatory that the application of these techniques be tempered with controlled clinical trials, documenting their effectiveness. The beneficial effects of new modalities must be documented as mechanical ventilation expands from use in the intensive care unit to use in standard medical wards and the patient's home. In these latter two settings, the vigilance of an intensive care unit is absent and the simplest method will be preferable. The requirement to demonstrate efficacy of new techniques with adequate studies is especially necessary now as the economics of health delivery have come under increasing scrutiny. Even more important than new technologies may be the efficacy of prolonged mechanical ventilation. A recent study by Spicher and White evaluated the outcome in 250 patients ventilated for 10 days or more at the Hershey Medical Center (Pennsylvania State University). The mortality, morbidity, and disability in patients in this study population requiring prolonged ventilation were extremely high. As these studies have pointed out, further evaluations of predictors of meaningful survival are necessary to avoid unnecessary human suffering and to best use limited resources. PMID:3280230

Grum, C M; Chauncey, J B

1988-03-01

152

Natural Ventilation of Parral Greenhouses  

Microsoft Academic Search

A study was carried out at the Experimental Station Las Palmerillas of Cajamar to characterise the natural ventilation of the parral greenhouse. An 882m2, five span, polyethylene film covered parral greenhouse was fitted with either a rolling or a flap ventilator attached to one side of each ridge and rolling ventilators in two 38m sidewalls. Ventilation rates for different configurations

J. Pérez Parra; E. Baeza; J. I. Montero; B. J. Bailey

2004-01-01

153

The perfused swine uterus model: long-term perfusion  

PubMed Central

Background It has previously been shown that the viability of swine uteri can be maintained within the physiological range in an open perfusion model for up to 8 hours. The aim of this study was to assess medium- to long-term perfusion of swine uteri using a modified Krebs–Ringer bicarbonate buffer solution (KRBB) in the established open perfusion model. Methods In an experimental study at an infertility institute, 30 swine uteri were perfused: group 1: n?=?11, KRBB; group 2: n?=?8, modified KRBB with drainage of perfusate supernatant; group 3: n?=?11, modified KRBB with drainage of perfusate every 2 h and substitution with fresh medium. Modified and conventional KRBB were compared with regard to survival and contraction parameters: intrauterine pressure (IUP), area under the curve (AUC), and frequency of contractions (F). Results Modified KRBB showed significantly higher IUP, AUC, and F values than perfusion with conventional KRBB. In group 3, the organ survival time of up to 17 h, with a 98% rate of effective contraction time, differed significantly from group 1 (P?perfusate substitution improves the open model for perfusion of swine uteri with regard to survival time and quality of contraction parameters. This model can be used for medium- to long-term perfusion of swine uteri, allowing further metabolic ex vivo studies in a cost-effective way and with little logistic effort.

2012-01-01

154

Why We Ventilate  

SciTech Connect

It is widely accepted that ventilation is critical for providing good indoor air quality (IAQ) in homes. However, the definition of"good" IAQ, and the most effective, energy efficient methods for delivering it are still matters of research and debate. This paper presents the results of work done at the Lawrence Berkeley National Lab to identify the air pollutants that drive the need for ventilation as part of a larger effort to develop a health-based ventilation standard. First, we present results of a hazard analysis that identified the pollutants that most commonly reach concentrations in homes that exceed health-based standards or guidelines for chronic or acute exposures. Second, we present results of an impact assessment that identified the air pollutants that cause the most harm to the U.S. population from chronic inhalation in residences. Lastly, we describe the implications of our findings for developing effective ventilation standards.

Logue, Jennifer M.; Sherman, Max H.; Price, Phil N.; Singer, Brett C.

2011-09-01

155

What Is a Ventilator?  

MedlinePLUS

... hospitals. Ventilators: Get oxygen into the lungs. Remove carbon dioxide from the body. (Carbon dioxide is a waste gas that can be ... NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings ...

156

Pulmonary ventilation during hemodialysis.  

PubMed

During hemodialysis a decrease in pulmonary ventilation has been reported. The elimination of CO2 across the dialyzer has been suggested as the cause of the pulmonary hypoventilation. Our purpose was to analyze the factors that could have influenced the pulmonary ventilation of 7 patients with chronic renal failure during hemodialysis, performed against an acetate dialysate with constant addition of CO2, bubbling into the dialysis bath. In spite of the large volume of CO2 mainly as bicarbonate, eliminated across the dialyzer there was no significant decrease of ventilation. The values of pH in the venous line were extremely low and the values of PvCO2 were artificially maintained around 35.0 mm Hg. Thus, the total CO2 delivered to the lungs, but mainly the levels of pH and PCO2 in the venous line play an important role in the control of pulmonary ventilation of these patients. PMID:6817152

Romaldini, H; Stabile, C; Faro, S; Lopes Dos Santos, M; Ramos, O L; Ratto, O R

1982-01-01

157

Methionine imbalance and toxicity in calves.  

PubMed

The occurrence of methionine imbalance and toxicity was examined using 70- and 100-kg Holstein bull calves. The animals had been trained to maintain reflex closure of the reticular groove after weaning at 5 wk of age, and Trials 1 (n = 30) and 2 (n = 24) were conducted on animals at 7 and 12 wk of age, respectively. Calves received a corn-soybean meal diet in Trial 1 and a corn-corn gluten meal diet in Trial 2. In Trial 1, postruminal administration of 6 g of DL-methionine/d increased ADG, feed intake, gain/feed, and N retention compared with a control group receiving N-free supplement. However, the administration of 12 g of DL-methionine/d did not improve these variables, whereas both 18 and 24 g/d resulted in BW loss and decreased gain/feed and N utilization efficiency. In Trial 2, postruminal administration of 16 g/d of L-lysine from L-lysine monohydrochloride increased ADG, gain/feed, and N utilization efficiency compared with a control group receiving a N-free supplement. The administration of 8 g of DL-methionine/d in addition to L-lysine did not exert an adverse effect on these variables. However, the additional supplementation of 16 and 24 g of DLmethionine/d negated the improvement, whereas 32 g/d resulted in BW loss and decreased gain/feed and N utilization efficiency. These results showed that a methionine imbalance and toxicity occurred in calves with even a modest excess of DL-methionine, and 70-kg calves were more susceptible to methionine toxicity than 100-kg calves. Plasma concentrations of branched-chain amino acids and phenylalanine linearly decreased with increasing amounts of additional DL-methionine from 0 to 32 g/d in Trial 2. However, such a decrease occurred mainly within the range from 0 to 12 g/d in Trial 1. This decrease was suggested to occur in relation to methionine metabolism via the transsulfuration pathway. PMID:11048939

Abe, M; Okada, H; Matsumura, D; Sato, H; Funaba, M; Iriki, T

2000-10-01

158

Conventional mechanical ventilation  

PubMed Central

The provision of mechanical ventilation for the support of infants and children with respiratory failure or insufficiency is one of the most common techniques that are performed in the Pediatric Intensive Care Unit (PICU). Despite its widespread application in the PICUs of the 21st century, before the 1930s, respiratory failure was uniformly fatal due to the lack of equipment and techniques for airway management and ventilatory support. The operating rooms of the 1950s and 1960s provided the arena for the development of the manual skills and the refinement of the equipment needed for airway management, which subsequently led to the more widespread use of endotracheal intubation thereby ushering in the era of positive pressure ventilation. Although there seems to be an ever increasing complexity in the techniques of mechanical ventilation, its successful use in the PICU should be guided by the basic principles of gas exchange and the physiology of respiratory function. With an understanding of these key concepts and the use of basic concepts of mechanical ventilation, this technique can be successfully applied in both the PICU and the operating room. This article reviews the basic physiology of gas exchange, principles of pulmonary physiology, and the concepts of mechanical ventilation to provide an overview of the knowledge required for the provision of conventional mechanical ventilation in various clinical arenas.

Tobias, Joseph D.

2010-01-01

159

Ventilator discontinuation protocols.  

PubMed

Mechanical ventilation is a life-saving supportive therapy, but it can also cause lung injury, diaphragmatic dysfunction, and lung infection. Ventilator liberation should be attempted as soon as clinically indicated, to minimize morbidity and mortality. The most effective method of liberation follows a systematic approach that includes a daily assessment of weaning readiness, in conjunction with interruption of sedation infusions and spontaneous breathing trials. Protocols and checklists are decision support tools that help ensure consistent application of key elements of evidence-based practice. A majority of studies of weaning protocols applied by non-physician healthcare providers suggest faster weaning and shorter duration of ventilation and ICU stay, and some suggest reduced failed extubation and ventilator-associated pneumonia rates. Checklists can be used to reinforce application of the protocol, or possibly in lieu of one, particularly in environments where the caregiver-to-patient ratio is high and clinicians are well versed in and dedicated to applying evidence-based care. There is support for integrating best-evidence rules for weaning into the mechanical ventilator so that a substantial portion of the weaning process can be automated, which may be most effective in environments with low caregiver-to-patient ratios or those in which it is challenging to consistently apply evidence-based care. This paper reviews evidence for ventilator liberation protocols and discusses issues of implementation and ongoing monitoring. PMID:23013902

Haas, Carl F; Loik, Paul S

2012-10-01

160

The effect of positive end-expiratory pressure (PEEP) ventilation in neurogenic pulmonary oedema  

Microsoft Academic Search

Summary The effect of positive end-expired pressure ventilation (PEEP) on mean systemic arterial pressure, mean pulmonary arterial pressure, mean pulmonary wedge pressure, mean intracranial pressure (ICP), and cerebral perfusion pressure (CPP), in a case of neurogenic pulmonary oedema (NPO) is presented. PEEP improved oxygenation, reduced, and finally stopped clinical pulmonary oedema. In this patient PEEP produced severe systemic hypotension. As

H. E. James; K. Tsueda; B. Wright; A. B. Young; J. McCloskey

1978-01-01

161

Keratinocyte Growth Factor Prevents Ventilator-induced Lung Injury in an Ex Vivo Rat Model  

Microsoft Academic Search

Mechanical ventilation has been shown to produce lung injury characterized by noncardiogenic pulmonary edema. Keratinocyte growth factor (KGF) is a heparin-binding growth factor that causes alveolar type II pneumocyte hyperplasia. KGF pretreatment and the resultant pneumocyte hyperplasia reduce fluid flux in models of lung injury. We utilized the isolated perfused rat lung model to produce lung injury by varying tidal

DAVID A. WELSH; WARREN R. SUMMER; ELIZABETH P. DOBARD; STEVE NELSON; CAROL M. MASON

162

High-frequency percussive ventilation for airway clearance in cystic fibrosis: a brief report.  

PubMed

Exacerbations of cystic fibrosis (CF) lung disease are characterized by increased inspissation of abnormally viscid pulmonary secretions with resultant plugging of small airways, worsened ventilation/perfusion mismatch, and increased physiological deadspace. In this circumstance, hypoxic respiratory failure necessitating mechanical ventilation can be life-threatening. We present such a case of CF lung disease poorly responsive to conventional mechanical ventilatory strategies, in which high-frequency percussive ventilation (HFPV) using volumetric diffusive respiration mobilized copious amounts of inspissated pulmonary secretions and improved refractory hypoxia. Subsequent transient hypercarbia necessitated titrating ventilator parameters to return the PaCO(2) to baseline; the voluminous clearance of secretions and improvement in oxygenation were sustained. HFPV appears unique in its ability to function as a methodological continuum from noninvasive percussion to invasive percussive ventilation for airway clearance, a fundamental tenet of the CF treatment paradigm. PMID:20602106

Dmello, Dayton; Nayak, Ravi P; Matuschak, George M

2010-07-03

163

Nutritional imbalance endorsed by televised food advertisements.  

PubMed

The ubiquity of television in American culture makes it a potential contributor to the obesogenic (obesity-causing) environment. Televised food advertisements, which encourage viewers to eat the foods promoted for sale, constitute a de facto set of dietary endorsements. The purpose of this study was to compare the nutritional content of food choices endorsed on television to nutritional guidelines. Using a cross-sectional design, food advertisements were observed during 84 hours of primetime and 12 hours of Saturday-morning televised broadcast during the fall of 2004. One-sample t tests were used to compare the food group servings of observed food items to the recommended daily servings and to compare the nutrient content of observed food items to the Daily Values. Results suggest that a diet consisting of observed food items would provide 2,560% of the recommended daily servings for sugars, 2,080% of the recommended daily servings for fat, 40% of the recommended daily servings for vegetables, 32% of the recommended daily servings for dairy, and 27% of the recommended daily servings for fruits. The same diet would substantially oversupply protein, total fat, saturated fat, cholesterol, and sodium, while substantially undersupplying carbohydrates, fiber, vitamins A, E, and D, pantothenic acid, iron, phosphorous, calcium, magnesium, copper, and potassium. Overall, the food choices endorsed on television fail to meet nutrition guidelines and encourage nutritional imbalance. PMID:20497780

Mink, Michael; Evans, Alexandra; Moore, Charity G; Calderon, Kristine S; Deger, Shannon

2010-06-01

164

Immunological hazards from nutritional imbalance in athletes.  

PubMed

This review examines the influences of nutritional imbalance on immune function of competitive athletes, who may adopt an unusual diet in an attempt to enhance performance. A major increase in body fat can have adverse effects on immune response. In contrast, a negative energy balance and reduction of body mass are likely to impair immune function in an already thin athlete. A moderate increase in polyunsaturated fat enhances immune function, but excessive consumption can be detrimental. Since endurance exercise leads to protein catabolism, an athlete may need 2.0 g/kg protein rather than the 0.7-1.0 g/kg recommended for a sedentary individual. Both sustained exercise and overtraining reduce plasma glutamine levels, which may contribute to suppressed immune function postexercise. A large intake of carbohydrate counters glutamine depletion but may also modify immune responses by altering the secretion of glucose-regulating hormones. Vitamins are important to immune function because of their antioxidant role. However, the clinical benefits of vitamin C supplementation are not enhanced by the use of more complex vitamin mixtures, and excessive vitamin E can have negative effects. Iron, selenium, zinc, calcium, and magnesium ion all influence immune function. Supplements may be required after heavy sweating, but an excessive intake of iron facilitates bacterial growth. In making dietary recommendations to athletes, it is important to recognize that immune response can be jeopardized not only by deficiencies but also by excessive intake of certain nutrients. The goal should be a well-balanced diet. PMID:9644093

Shephard, R J; Shek, P N

1998-01-01

165

Ventilation strategies for different climates  

SciTech Connect

Until recently, residential ventilation in the United States has been provided by infiltration. In this report we compare natural ventilation (ventilation by infiltration) with several mechanical ventilation strategies and examine the overall energy consumption associated with these strategies in different climatic regions in the US. The strategies examined are: natural ventilation, balanced ventilation with an air-to-air heat exchanger, exhaust ventilation without heat recovery, and exhaust ventilation with heat recovery via a heat pump. Two strategies for utilizing the heat pump output for domestic hot water are examined. One heat pump strategy employs exhaust fan reversal to provide space cooling whenever possible during the summer months. A modified TRNSYS residential load model incorporating the LBL infiltration model, an algorithm to calculate effective ventilation, and a modified TRNSYS domestic hot water model are used to simulate the energy consumption associated with each strategy. The domestic hot water model is used to determine the useful heat supplied by an exhaust ventilation heat pump as a function of daily hot water demand. The simulations indicate that the choice of ventilation strategy can have a significant impact on energy consumption. They show that total end-use energy consumption can be reduced as much by mechanical ventilation as by superinsulation of a house. The comparisons also show that for the same effective ventilation rate, houses with mechanical ventilation systems (especially those with exhaust fans) have been indoor air quality than those that rely on natural ventilation. 19 refs.

Feustel, H.E.; Modera, M.P.; Rosenfeld, A.H.

1987-03-01

166

The Fractal Conception of the Imbalance of Water in Nature  

NASA Astrophysics Data System (ADS)

Let us look at an example of a water inflow system. Let's consider the Water-Inflow Generator in picture 1. Then the Watershed Fractal in picture 2. Let us look at some water consuming systems. Let's consider the Water-Consuming Generator in picture 3. Then the Water-Consuming Fractal in picture 4. Then the Water-Imbalance Fractal in picture 5. Then the Balance-Imbalance Points are illustrated in pictures 6, 7, 8, etc. Every Shoulder of any Generators has some Processing in this Shoulder. Every Shoulder can include several various Processes. Every Shoulder is unique. The Point of Balance-Imbalance is located between the Water-Inflow Shoulders and the Water-Consumption Shoulders. Only on this Point does it make sense to talk about the Balance or Imbalance of Water in Nature. It's hard to believe that all the Processes into all the Shoulders are going so that the Point of Balance-Imbalance will be always in the Balance condition. The more convincing argument is to think that is at any Point of Balance-Imbalance there is a normal state of Imbalance. The state of Balance can be in principle, but only as the very rare and a very short time between Imbalance Falling and the Imbalance Increasing. For easier discussion we have used the very simple generators only with two shoulders. The real systems have many different shoulders. The dimension of the real systems, of course, greatly complicates the solution of practical problems of the Management of the Imbalance of Water in Nature. But in our case it doesn't matter. We have shown that even in the simplest model of the Management of the Imbalance of Water in Nature too far exceeds the capability of traditional logic. It is necessary to consider some new special methods for solving such problems. But about this it is necessary to read other publications. Now it is important to note that the Imbalance of Water in Nature is the basic state of Nature.

Shlafman, L.; Kontar, V. A.

2011-12-01

167

Strip sign: a new sign for diagnosis of nonembolic defects on pulmonary perfusion scintigraphy  

SciTech Connect

A total of 47 patients who underwent both lung ventilation-perfusion scintigraphy and pulmonary arteriography were evaluated for presence on the scintigram of perfusion defects that did not extend to the lung edge, leaving a peripheral parenchymal stripe (PPS) of perfused lung between the defect and the adjacent pleural surface. Scans were scored both with and without regard for the PPS according to probability of pulmonary embolism; these predictions were then compared with the official lung scan report given initially to the referring physician. Predictions were then verified by pulmonary arteriography. Of the 13 patients who showed one or more PPSs, four reports would have been more accurate using the revised criteria that included the stripe sign. In this study, visualization of a PPS in an area of defect on a perfusion lung scan was extremely accurate for predicting absence of pulmonary emboli in the specific area of the stripe. Further studies that would be needed to confirm this finding are discussed.

Sostman, H.D.; Gottschalk, A.

1982-03-01

168

Electrolyte imbalance triggering relapse of inflammatory neuropathy.  

PubMed

Electrolyte imbalance is a well-known cause of acute neurological deterioration in the central and peripheral nervous systems. Rapid correction of hyponatraemia1 can cause central pontine myelinolysis, and in muscle tetany may result from hypocalcaemia. However the role of electrolyte imbalance in peripheral neuropathy although well-described is encountered less frequently. We describe a case of a 71 year old female with a fourteen year history of chronic inflammatory demyelinating polyneuropathy (CIDP) and stable monoclonal gammopathy, normally maintained on three-weekly intravenous immunoglobulin (IVIG) therapy. At her best baseline, she has a normal motor examination and reduced vibration sense only to the ankles. She presented with a four week history of progressive numbness and paresthesiae in all four limbs, reduced balance, a decline in mobility with frequent falls and reduced hand function. The deterioration developed after a week of non-bloody diarrhoea with night sweats but continued to progress through two courses of her regular IVIG. She also had a past history of breast cancer, hypertension and a duodenal ulcer. On examination she had a profound sensory ataxia and pseudo-athetosis of the upper limbs. Power was preserved. Pinprick was reduced to the forearm and thighs. Vibration sense was present only at the sternum. Proprioception was reduced to the shoulders and hips. She was areflexic. General examination was normal. Blood investigations showed hypomagnesaemia of 0.1 (range 0.6-1.0), hypocalcaemia of 1.75 (range 2.15-2.55), mild hypokalaemia of 3.2 (range 3.5-5.1) but stable renal function. Nerve conduction studies showed a length-dependent demyelinating sensorimotor neuropathy with significant deterioration from previous studies. Her paraprotein level was stably low. Thus we considered the metabolic disturbance as a potential cause of her acute severe relapse of her CIDP. The diarrhoea resolved spontaneously and potassium and calcium levels normalised after oral treatment. However the hypomagnesaemia required high-dose oral and intravenous supplementation. Investigations for a malabsorption syndrome were negative. She was taking two medications known to be associated with hypomagnesaemia. After stopping indapamide, a thiazide-like diuretic, her urine magnesium output was low, so a renal cause was unlikely. Omeprazole, which had been doubled in the last year after the diagnosis of her duodenal ulcer, is known in multiple case series to be associated with severe symptomatic hypomagnesaemia that is thought to be a class effect of proton pump inhibitors (PPIs).(2) This prompted us to halve the dose of omeprazole. Her serum magnesium level stabilised in the low-to-normal range and she was treated with two further courses of 2 g/kg IVIG. She had a marked improvement in sensory examination and functional ability. Her proprioceptive loss and sensory ataxia resolved. A logical approach to investigating for reversible causes for her deterioration pointed to drug-induced hypomagnesaemia as a potentially important cause of acute decompensation in CIDP. Her severe relapse remained refractory to treatment until her metabolic disturbance was normalised, after which she showed an excellent response. PMID:24108985

Keshavan, A; Gandhi, S; Lunn, Mp; Reilly, Mm

2013-11-01

169

Perfusion Based Cell Culture Chips  

Microsoft Academic Search

\\u000a Performing cell culture in miniaturized perfusion chambers gives possibilities to experiment with cells under near in vivo like conditions. In contrast to traditional batch cultures, miniaturized perfusion systems provide precise control of medium\\u000a composition, long term unattended cultures and tissue like structuring of the cultures. However, as this chapter illustrates,\\u000a many issues remain to be identified regarding perfusion cell culture

A. Heiskanen; J. Emnéus; M. Dufva

2010-01-01

170

Perfusion Based Cell Culture Chips  

NASA Astrophysics Data System (ADS)

Performing cell culture in miniaturized perfusion chambers gives possibilities to experiment with cells under near in vivo like conditions. In contrast to traditional batch cultures, miniaturized perfusion systems provide precise control of medium composition, long term unattended cultures and tissue like structuring of the cultures. However, as this chapter illustrates, many issues remain to be identified regarding perfusion cell culture such as design, material choice and how to use these systems before they will be widespread amongst biomedical researchers.

Heiskanen, A.; Emnéus, J.; Dufva, M.

171

Lung-derived soluble mediators are pathogenic in ventilator-induced lung injury.  

PubMed

Ventilator-induced lung injury (VILI) due to high tidal volume (V(T)) is associated with increased levels of circulating factors that may contribute to, or be markers of, injury. This study investigated if exclusively lung-derived circulating factors produced during high V(T) ventilation can cause or worsen VILI. In isolated perfused mouse lungs, recirculation of perfusate worsened injury (compliance impairment, microvascular permeability, edema) induced by high V(T). Perfusate collected from lungs ventilated with high V(T) and used to perfuse lungs ventilated with low V(T) caused similar compliance impairment and permeability and caused a dose-dependent decrease in transepithelial electrical resistance (TER) across rat distal lung epithelial monolayers. Circulating soluble factors derived from the isolated lung thus contributed to VILI and had deleterious effects on the lung epithelial barrier. These data demonstrate transferability of an injury initially caused exclusively by mechanical ventilation and provides novel evidence for the biotrauma hypothesis in VILI. Mediators of the TER decrease were heat-sensitive, transferable via Folch extraction, and (following ultrafiltration, 3 kDa) comprised both smaller and larger molecules. Although several classes of candidate mediators, including protein cytokines (e.g., tumor necrosis factor-?, interleukin-6, macrophage inflammation protein-1?) and lipids (e.g., eicosanoids, ceramides, sphingolipids), have been implicated in VILI, only prostanoids accumulated in the perfusate in a pattern consistent with a pathogenic role, yet cyclooxygenase inhibition did not protect against injury. Although no single class of factor appears solely responsible for the decrease in barrier function, the current data implicate lipid-soluble protein-bound molecules as not just markers but pathogenic mediators in VILI. PMID:21239530

Jaecklin, Thomas; Engelberts, Doreen; Otulakowski, Gail; O'Brodovich, Hugh; Post, Martin; Kavanagh, Brian P

2011-01-14

172

Air leaks localized with lung ventilation SPECT.  

PubMed

A 61-year-old man with severe chronic obstructive pulmonary disease presented to our hospital with recurrence of a right-sided spontaneous secondary pneumothorax. Thoracoscopic abrasion of the parietal pleura was performed, but an important air leak persisted. Presumed to originate from a bulla in the right upper lobe, bullectomy and pleural decortication were performed, but leakage remained. Lobectomy was considered, and quantitative ventilation/perfusion SPECT was performed to predict the functional outcome.Fused high-resolution CT/Tc Technegas images localized leakage not only to a bleb in the right upper lobe but also to the subcutaneous emphysema in the thoracic wall. The air leak resolved after conservative treatment. PMID:22996237

Ceulemans, Gaetane; De Meirleir, Liesbeth; Keyaerts, Marleen; Smets, Dirk; Verdries, Douwe; Vincken, Walter; Everaert, Hendrik

2012-12-01

173

Ventilator associated pneumonia  

PubMed Central

Hospital acquired or nosocomial infections continue to be an important cause of morbidity and mortality. The critically ill patient is at particular risk of developing intensive care unit acquired infection, with the lungs being especially vulnerable. Nosocomial bacterial pneumonia occurring after two days of mechanical ventilation is referred to as ventilator associated pneumonia, and is the most common nosocomial infection seen in the intensive care unit. Intubation of the trachea and mechanical ventilation is associated with a 7?fold to 21?fold increase in the incidence of pneumonia and up to 28% of patients receiving mechanical ventilation will develop this complication. Its development is associated with an attributable increase in morbidity and mortality. The establishment of an accurate diagnosis of ventilator associated pneumonia remains problematic and as yet there is still no accepted “gold standard” for diagnosis. The responsible pathogens vary according to case mix, local resistance patterns, and methodology of sampling. However, there is general agreement that rapid initiation of appropriate antimicrobial therapy improves outcome.

Hunter, J D

2006-01-01

174

A microprocessor based feedback controller for mechanical ventilation.  

PubMed

A microcomputer feedback system has been developed which adjusts the inspired minute volume of a ventilator based on the patient's end-tidal CO2 concentration. The feedback controlled ventilator was evaluated in 6 dogs (18-20 kg). Arterial PCO2 was monitored continuously while end-tidal CO2 concentration was controlled by the micro-computer system and the following perturbations introduced: [1] NaHCO3 was infused IV, [2] a pulmonary artery was occluded, [3] one lumen of a double lumen endobronchial tube was occluded, and [4] an air embolism was given. The end-tidal PCO2 controller kept PaCO2 within 1.2 mm Hg of the desired value when CO2 production increased by as much as 44%. Changing the ventilation/perfusion ratios caused differences as large as 22 mm Hg between the arterial and end-tidal PCO2 and the controller was not effective in keeping PaCO2 at the desired level. Closed loop control of ventilation based on end-tidal PCO2 measurements successfully compensated for increases in CO2 production keeping PaCO2 constant. The controller did not, however, keep PaCO2 at the desired level when significant changes occurred in the distribution of blood flow to ventilation. PMID:6819792

Ohlson, K B; Westenskow, D R; Jordan, W S

1982-01-01

175

Workaholism, work stress, work-life imbalance: exploring gender's role  

Microsoft Academic Search

Purpose – The purpose of this paper is to examine potential differences between male and female workaholics in relation to work stress and work-life imbalance; also to test for gender as a moderator in the relation between workaholism with work stress and work-life imbalance. Design\\/methodology\\/approach – An exploratory approach was used to examine employees on workaholism, work stress, and work-life

Shahnaz Aziz; Jamie Cunningham

2008-01-01

176

The Media and the Chemical Imbalance Theory of Depression  

Microsoft Academic Search

The cause of mental disorders such as depression remains unknown. However, the idea that neurotransmitter imbalances cause\\u000a depression is vigorously promoted by pharmaceutical companies and the psychiatric profession at large. We examine media reports\\u000a referring to this chemical imbalance theory and ask reporters for evidence supporting their claims. We then report and critique\\u000a the scientific papers and other confirming evidence

Jonathan Leo; Jeffrey R. Lacasse

2008-01-01

177

MIMO OFDM Receivers for Systems With IQ Imbalances  

Microsoft Academic Search

Orthogonal frequency division multiplexing (OFDM) is a widely recognized modulation scheme for high data rate communications. However, the implementation of OFDM-based systems suffers from in-phase and quadrature-phase (IQ) imbalances in the front-end analog processing. Such imbalances are caused by the analog processing of the received radio frequency (RF) signal, and they cannot be efficiently or entirely eliminated in the analog

Alireza Tarighat; Ali H. Sayed

2005-01-01

178

Ventilation technologies scoping study  

SciTech Connect

This document presents the findings of a scoping study commissioned by the Public Interest Energy Research (PIER) program of the California Energy Commission to determine what research is necessary to develop new residential ventilation requirements for California. This study is one of three companion efforts needed to complete the job of determining the needs of California, determining residential ventilation requirements, and determining appropriate ventilation technologies to meet these needs and requirements in an energy efficient manner. Rather than providing research results, this scoping study identifies important research questions along with the level of effort necessary to address these questions and the costs, risks, and benefits of pursuing alternative research questions. In approaching these questions and level of effort, feasibility and timing were important considerations. The Commission has specified Summer 2005 as the latest date for completing this research in time to update the 2008 version of California's Energy Code (Title 24).

Walker, Iain S.; Sherman, Max H.

2003-09-30

179

Overdistension in ventilated children  

PubMed Central

Ventilating patients with acute respiratory failure according to standardized recommendations can lead to varying volume–pressure (V-P) relationships and overdistension. Young children may be more susceptible than adults to overdistension, and individual evaluation of the effects of ventilator settings is therefore required. Three studies have applied indices for the detection of overdistension to dynamic V-P curves in ventilated children. Two of those studies compared these indices to those obtained using a reference technique ([quasi]-static V-P curves), and suggested that the c coefficient of a second order polynomial equation (SOPE) and the ratio of the volume-dependent elastance to total dynamic elastance (%E2) were suitable indices for estimating overdistension.

Neve, Veronique; Leclerc, Francis; Roque, Eric Dumas de la; Leteurtre, Stephane; Riou, Yvon

2001-01-01

180

Meeting Residential Ventilation Standards Through Dynamic Control of Ventilation Systems  

SciTech Connect

Existing ventilation standards, including American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) Standard 62.2, specify continuous operation of a defined mechanical ventilation system to provide minimum ventilation, with time-based intermittent operation as an option. This requirement ignores several factors and concerns including: other equipment such as household exhaust fans that might incidentally provide ventilation, negative impacts of ventilation when outdoor pollutant levels are high, the importance of minimizing energy use particularly during times of peak electricity demand, and how the energy used to condition air as part of ventilation system operation changes with outdoor conditions. Dynamic control of ventilation systems can provide ventilation equivalent to or better than what is required by standards while minimizing energy costs and can also add value by shifting load during peak times and reducing intake of outdoor air contaminants. This article describes the logic that enables dynamic control of whole-house ventilation systems to meet the intent of ventilation standards and demonstrates the dynamic ventilation system control concept through simulations and field tests of the Residential Integrated Ventilation-Energy Controller (RIVEC).

Sherman, Max H.; Walker, Iain S.

2011-04-01

181

Conventional gas ventilation, liquid-assisted high-frequency oscillatory ventilation, and tidal liquid ventilation in surfactant-treated preterm lambs.  

PubMed

This study was designed to compare the efficacy and potential protective or injurious effects of tidal liquid ventilation (TLV), liquid-assisted high-frequency oscillatory ventilation (LA-HFOV), and high PEEP conventional mechanical ventilation (CMV) in neonatal respiratory distress syndrome. Preterm lambs (124-126 days gestation), prophylactically treated with natural surfactant, were allocated to one of the treatment modalities or to an untreated fetal control group (F), euthanised after tracheal ligation. LA-HFOV animals received an intratracheal loading dose of 5 mL x kg(-1) followed by a continuous intrapulmonary instillation of 12 mL x kg(-1);h(-1) FC-75 perfluorocarbon liquid. The ventilation strategies aimed at keeping clinically appropriate arterial blood gases for a study period of 5 hours. A histological lung injury score was calculated and semiquantitative morphometry was performed on lung tissue fixed by vascular perfusion. The alveolar-arterial pressure difference for O2 was significantly lower throughout the study in TLV compared to CMV lambs; at 1, 2, and 5 hours, oxygenation was better in TLV when compared to LA-HFOV. Total lung injury scores in TLV lambs were significantly lower than in either CMV or LA-HFOV animals, but higher when compared to F. CMV and LA-HFOV induced an excess of collapsed and overdistended alveoli, whereas in TLV alveolar expansion was normally distributed around predominantly normal alveoli. CMV and LA-HFOV, but not TLV, were associated with an excess of dilated airways. Thus, in the ovine neonatal RDS model, TLV compared favourably to either gas ventilation strategy by its more uniform ventilation, reduced lung injury, and improved gas exchange. PMID:11132020

Degraeuwe, P L; Thunnissen, F B; Jansen, N J; Dormaar, J T; Dohmen, L R; Blanco, C E

2000-11-01

182

Ventilation effects on combustion products  

Microsoft Academic Search

The effects of fire ventilation on combustion products are expressed in terms of relationship between concentration of products and equivalence ratio, ?. For well-ventilated fires, ? < 1.0, where mostly heat and products of complete combustion (such as CO2 and water) are generated. For ventilation-controlled fires, ? > 1.0, where mostly products of incomplete combustion are generated with very high

A Tewarson

1996-01-01

183

Ventilation requirements for uranium mines  

Microsoft Academic Search

The planning and operation of ventilation network systems for uranium mines require special considerations since ventilation is the primary technique of controlling ambient concentrations of radon progeny. The major environmental challenge facing the ventilation engineer is the requirement to dilute radon progeny to below the Working Level Month per year of worker exposure required by law. The application of large

C. Gherghel; E. De Souza

184

Measure Guideline: Ventilation Cooling  

SciTech Connect

The purpose of this measure guideline on ventilation cooling is to provide information on a cost-effective solution for reducing cooling system energy and demand in homes located in hot-dry and cold-dry climates. This guideline provides a prescriptive approach that outlines qualification criteria, selection considerations, and design and installation procedures.

Springer, D.; Dakin, B.; German, A.

2012-04-01

185

Positive pressure mechanical ventilation  

Microsoft Academic Search

Andreas Wesele Vesalius documented the first known attempt at assisted ventilation in 1555. He observed, ''An opening must be attempted in the trunk of the trachea, into which a tube of reed or cane should be put; you will then blow into this, so that the lung may rise again and the animal take in air.'' Though primitive, this formed

Bhargavi Gali; Deepi G. Goyal

2003-01-01

186

Laboratory Ventilation and Safety.  

ERIC Educational Resources Information Center

|In order to meet the needs of both safety and economy, laboratory ventilation systems must effectively remove air-borne toxic and flammable materials and at the same time exhaust a minimum volume of air. Laboratory hoods are the most commonly used means of removing gases, dusts, mists, vapors, and fumed from laboratory operations. To be…

Steere, Norman V.

1965-01-01

187

Laboratory Ventilation and Safety.  

ERIC Educational Resources Information Center

In order to meet the needs of both safety and economy, laboratory ventilation systems must effectively remove air-borne toxic and flammable materials and at the same time exhaust a minimum volume of air. Laboratory hoods are the most commonly used means of removing gases, dusts, mists, vapors, and fumed from laboratory operations. To be effective,…

Steere, Norman V.

1965-01-01

188

Ventilator-associated pneumonia  

Microsoft Academic Search

Ventilator-associated pneumonia is the most common nosocomial infection. Mortality rates, morbidity, and costs are all increased in the patient with VAP, and every measure should thus be taken to prevent its development. There are several clearly defined risk factors for VAP, and awareness of these can facilitate early diagnosis and hence treatment. In this article, we discuss the risk factors,

J.-L Vincent

2004-01-01

189

Supercavitation Ventilation Control System.  

National Technical Information Service (NTIS)

A supercavitation ventilation control system is disclosed and includes a vehicle body having a fore end and an aft end. A cavitator is fit to the fore end of the vehicle body, the cavitator generating a gas cavity around the vehicle body. A cavity control...

R. Kuklinski

2002-01-01

190

RESIDENTIAL VENTILATION STUDY  

EPA Science Inventory

This project evaluated the effectiveness, first costs and operational costs of various types of residential ventilation systems in three different climates in the U.S. The Agency, through its Energy Star Program, recommends that builders construct homes that are energy efficient ...

191

Intermedin Stabilized Endothelial Barrier Function and Attenuated Ventilator-induced Lung Injury in Mice  

PubMed Central

Background Even protective ventilation may aggravate or induce lung failure, particularly in preinjured lungs. Thus, new adjuvant pharmacologic strategies are needed to minimize ventilator-induced lung injury (VILI). Intermedin/Adrenomedullin-2 (IMD) stabilized pulmonary endothelial barrier function in vitro. We hypothesized that IMD may attenuate VILI-associated lung permeability in vivo. Methodology/Principal Findings Human pulmonary microvascular endothelial cell (HPMVEC) monolayers were incubated with IMD, and transcellular electrical resistance was measured to quantify endothelial barrier function. Expression and localization of endogenous pulmonary IMD, and its receptor complexes composed of calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMPs) 1–3 were analyzed by qRT-PCR and immunofluorescence in non ventilated mouse lungs and in lungs ventilated for 6 h. In untreated and IMD treated mice, lung permeability, pulmonary leukocyte recruitment and cytokine levels were assessed after mechanical ventilation. Further, the impact of IMD on pulmonary vasoconstriction was investigated in precision cut lung slices (PCLS) and in isolated perfused and ventilated mouse lungs. IMD stabilized endothelial barrier function in HPMVECs. Mechanical ventilation reduced the expression of RAMP3, but not of IMD, CRLR, and RAMP1 and 2. Mechanical ventilation induced lung hyperpermeability, which was ameliorated by IMD treatment. Oxygenation was not improved by IMD, which may be attributed to impaired hypoxic vasoconstriction due to IMD treatment. IMD had minor impact on pulmonary leukocyte recruitment and did not reduce cytokine levels in VILI. Conclusions/Significance IMD may possibly provide a new approach to attenuate VILI.

Muller-Redetzky, Holger Christian; Kummer, Wolfgang; Pfeil, Uwe; Hellwig, Katharina; Will, Daniel; Paddenberg, Renate; Tabeling, Christoph; Hippenstiel, Stefan; Suttorp, Norbert; Witzenrath, Martin

2012-01-01

192

Chromosome 11 allele imbalance and clinicopathological correlates in ovarian tumours.  

PubMed Central

Allele imbalance on chromosome 11 loci in ovarian cancer is a frequent event, suggesting the presence of tumour-suppressor genes for ovarian carcinogenesis on this chromosome. Ten highly polymorphic (CA) repeat microsatellites were used to determine allele imbalance in 60 primary ovarian tumours, including 47 epithelial ovarian cancers (EOCs). Forty EOCs (85%) showed allele imbalance at one or more loci, and in 39 of these (83%) the data suggested subchromosomal deletions: eight of 11p only; six of 11q only; and 25 of both 11p and 11q. Three consensus regions of deletion were indicated at 11p15.5-p15.3, 11q12-q22 and 11q23.3-q24.1. Allele imbalance at the 11q subtelomeric region (D11S912) correlated significantly with adverse survival, while imbalance at 11q14.3 and retention of heterozygosity at 11q22 (close to the site of the progesterone receptor gene) were associated with favourable clinicopathological features. The findings allow development of a preliminary model for the molecular evolution of epithelial ovarian cancer. Images Figure 1

Gabra, H.; Taylor, L.; Cohen, B. B.; Lessels, A.; Eccles, D. M.; Leonard, R. C.; Smyth, J. F.; Steel, C. M.

1995-01-01

193

Mitonuclear protein imbalance as a conserved longevity mechanism.  

PubMed

Longevity is regulated by a network of closely linked metabolic systems. We used a combination of mouse population genetics and RNA interference in Caenorhabditis elegans to identify mitochondrial ribosomal protein S5 (Mrps5) and other mitochondrial ribosomal proteins as metabolic and longevity regulators. MRP knockdown triggers mitonuclear protein imbalance, reducing mitochondrial respiration and activating the mitochondrial unfolded protein response. Specific antibiotics targeting mitochondrial translation and ethidium bromide (which impairs mitochondrial DNA transcription) pharmacologically mimic mrp knockdown and extend worm lifespan by inducing mitonuclear protein imbalance, a stoichiometric imbalance between nuclear and mitochondrially encoded proteins. This mechanism was also conserved in mammalian cells. In addition, resveratrol and rapamycin, longevity compounds acting on different molecular targets, similarly induced mitonuclear protein imbalance, the mitochondrial unfolded protein response and lifespan extension in C. elegans. Collectively these data demonstrate that MRPs represent an evolutionarily conserved protein family that ties the mitochondrial ribosome and mitonuclear protein imbalance to the mitochondrial unfolded protein response, an overarching longevity pathway across many species. PMID:23698443

Houtkooper, Riekelt H; Mouchiroud, Laurent; Ryu, Dongryeol; Moullan, Norman; Katsyuba, Elena; Knott, Graham; Williams, Robert W; Auwerx, Johan

2013-05-23

194

Noisy Ventilation Improves Lung Function  

NASA Astrophysics Data System (ADS)

It has been shown that mechanical ventilation in the setting of acute lung injury may propagate additional injury within the lung and numerous studies have been carried out to determine the optimal method of minimizing ventilator induced lung injury while still maintaining life-sustaining gas exchange. We have found that noise added to tidal volume and frequency, called noisy ventilation, during mechanical ventilation improves both lung mechanics and oxygenation in a rodent model of acute lung injury. Additionally, the standard deviation of the noise appears to be directly related to the magnitude of improvements seen with this ventilation modality in a manner similar to stochastic resonance. Furthermore, healthy guinea pigs that underwent with noisy ventilation exhibited increased surfactant content and reduced plasma proteins than their conventionally ventilated counterparts within the alveolar space of the lung. This suggests that not only did noisy ventilation induce endogenous surfactant release, but also served to reduce ventilator induced lung injury in this animal model. In conclusion, noisy ventilation improves blood oxygenation during acute lung injury and also serves to enhance lung function and reduce ventilator induced lung injury in healthy lungs.

Suki, Béla; Arold, Stephen P.; Alencar, Adriano; Lutchen, Kenneth R.; Ingenito, Edward P.

2003-05-01

195

ASHRAE and residential ventilation  

SciTech Connect

In the last quarter of a century, the western world has become increasingly aware of environmental threats to health and safety. During this period, people psychologically retreated away from outdoors hazards such as pesticides, smog, lead, oil spills, and dioxin to the seeming security of their homes. However, the indoor environment may not be healthier than the outdoor environment, as has become more apparent over the past few years with issues such as mold, formaldehyde, and sick-building syndrome. While the built human environment has changed substantially over the past 10,000 years, human biology has not; poor indoor air quality creates health risks and can be uncomfortable. The human race has found, over time, that it is essential to manage the indoor environments of their homes. ASHRAE has long been in the business of ventilation, but most of the focus of that effort has been in the area of commercial and institutional buildings. Residential ventilation was traditionally not a major concern because it was felt that, between operable windows and envelope leakage, people were getting enough outside air in their homes. In the quarter of a century since the first oil shock, houses have gotten much more energy efficient. At the same time, the kinds of materials and functions in houses changed in character in response to people's needs. People became more environmentally conscious and aware not only about the resources they were consuming but about the environment in which they lived. All of these factors contributed to an increasing level of public concern about residential indoor air quality and ventilation. Where once there was an easy feeling about the residential indoor environment, there is now a desire to define levels of acceptability and performance. Many institutions--both public and private--have interests in Indoor Air Quality (IAQ), but ASHRAE, as the professional society that has had ventilation as part of its mission for over 100 years, is the logical place to provide leadership. This leadership has been demonstrated most recently by the publication of the first nationally recognized standard on ventilation in homes, ASHRAE Standard 62.2-2003, which builds on work that has been part of ASHRAE for many years and will presumably continue. Homeowners and occupants, which includes virtually all of us, will benefit from the application of Standard 62.2 and use of the top ten list. This activity is exactly the kind of benefit to society that the founders of ASHRAE envisioned and is consistent with ASHRAE's mission and vision. ASHRAE members should be proud of their Society for taking leadership in residential ventilation.

Sherman, Max H.

2003-10-01

196

Itinerant ferromagnetism in an interacting Fermi gas with mass imbalance  

SciTech Connect

We study the emergence of itinerant ferromagnetism in an ultracold atomic gas with a variable mass ratio between the up- and down-spin species. Mass imbalance breaks the SU(2) spin symmetry, leading to a modified Stoner criterion. We first elucidate the phase behavior in both the grand canonical and canonical ensembles. Second, we apply the formalism to a harmonic trap to demonstrate how a mass imbalance delivers unique experimental signatures of ferromagnetism. These could help future experiments to better identify the putative ferromagnetic state. Furthermore, we highlight how a mass imbalance suppresses the three-body loss processes that handicap the formation of a ferromagnetic state. Finally, we study the time-dependent formation of the ferromagnetic phase following a quench in the interaction strength.

Keyserlingk, C. W. von [Rudolf Peierls Centre for Theoretical Physics, 1 Keble Road, Oxford OX1 3NP (United Kingdom); Conduit, G. J. [Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100 (Israel); Physics Department, Ben Gurion University, Beer Sheva 84105 (Israel)

2011-05-15

197

New electromechanical balancing device for active imbalance compensation  

NASA Astrophysics Data System (ADS)

New type of electromechanical balancing device that can be used for active compensation of variable imbalance of a rotational machine is proposed. The balancing device is in a shape of ring with a number of grooves displaced around the axis of rotation. Balancing members (steel balls) are placed into the grooves, and a driving electromagnetic device is used to actively control the movement of the balancing members. The balancing members are moved between radially inner position and radially outer position of the ring. When the proposed device is attached to a rotating machine, the driving electromagnetic device is activated to generate a force on a selected balancing member, so as to displace it and to vary the balancing status. The main advantage of the proposed device is in its capability to reduce rotational imbalance in applications where the value and position of imbalance is variable. The paper presents both finite element analysis results and experimental results of prototype design.

Hredzak, Branislav; Guo, Guoxiao

2006-07-01

198

Non-Invasive Ventilation  

Microsoft Academic Search

Mechanical ventilation represents the most widely used supportive technique in the intensive care unit (ICU). Without mechanical\\u000a support for respiration, many patients would die within a few hours due to acute hypoxaemic and hypercapnic respiratory failure.\\u000a Several forms of external support for respiration have been described in the literature to assist the failing ventilatory\\u000a system. Chief among these is endotracheal

A. Peratoner; V. Antonaglia; U. Lucangelo

199

SHOULDER MUSCLE IMBALANCE AND SUBACROMIAL IMPINGEMENT SYNDROME IN OVERHEAD ATHLETES  

PubMed Central

Subacromial impingement is a frequent and painful condition among athletes, particularly those involved in overhead sports such as baseball and swimming. There are generally two types of subacromial impingement: structural and functional. While structural impingement is caused by a physical loss of area in the subacromial space due to bony growth or inflammation, functional impingement is a relative loss of subacromial space secondary to altered scapulohumeral mechanics resulting from glenohumeral instability and muscle imbalance. The purpose of this review is to describe the role of muscle imbalance in subacromial impingement in order to guide sports physical therapy evaluation and interventions.

2011-01-01

200

Dihadron momentum imbalance and correlations in d+Au collisions  

NASA Astrophysics Data System (ADS)

We calculate in perturbative QCD the transverse momentum imbalance of dijet and dihadron production in high-energy p+A (d+A) collisions. We evaluate the effect of both initial- and final-state multiple scattering, which determines the strength of this transverse momentum imbalance. Combining this new result with the suppression of the cross section in d+Au collisions, which arises from cold nuclear matter energy loss and coherent power corrections, we are able to describe the dihadron correlations measured by both PHENIX and STAR collaborations at RHIC, including mid-mid, mid-forward, and forward-forward rapidity hadron pairs.

Kang, Zhong-Bo; Vitev, Ivan; Xing, Hongxi

2012-03-01

201

The virtual absence of stress-ulceration related bleeding in ICU patients receiving prolonged mechanical ventilation without any prophylaxis  

Microsoft Academic Search

Objective: To study the incidence of stress-ulcer related bleeding in ICU patients receiving prolonged (> 2 days) mechanical ventilation without any stress ulcer- ation prophylaxis. Design: A prospective cohort study in 183 patients. Interventions: All patients received clinical treatment in- cluding maintenance of adequate tissue perfusion (with low dose inotropes and vasodilators), infection preven- tion (by selective decontamination of the

D. F. Zandstra; Ch. P. Stoutenbeek

1994-01-01

202

Electric Fields in Perfused Nerves  

Microsoft Academic Search

IN perfusion experiments with squid giant axons, the internal potassium concentration Ki can be reduced either by substitution of other univalent ions, so that both ionic strength si and osmolality are kept constant, or by dilution with non-electrolytes at constant osmolality. The importance of non-electrolyte perfusion in testing various models of resting potential difference (p.d.) and action potential is emphasized

L. Bass; W. J. Moore

1967-01-01

203

Blood perfusion and pH monitoring in organs by laser-induced fluorescence spectroscopy  

NASA Astrophysics Data System (ADS)

Sensitivity of laser-induced fluorescence spectroscopy (LIFS) in detecting a change in tissue pH, and blood perfusion was determined. Rabbits were anesthetized, paralyzed, and mechanically ventilated. The arterial and venous blood supplies of the kidney were isolated and ligated to alter the perfusion. The femoral artery was cannulated to extract samples for blood gas analysis. A 308-nm XeCl was used as an excitation source. A 600 micrometers core diameter fiber was used for fluorescence acquisition, and the spectra analyzed by an optical multichannel analyzer (EG & G, OMA III). the corresponding intensity ratio R equals INADH / ICOLL was used as an index for respiratory acidosis. Blood perfusion was assessed using the following algorithm: (IELAS minus ICOLL) divided by (INADH minus ICOLL). The intensity ratio linearly decreased with the reduction of blood perfusion. When we totally occluded the artery the ratio decreased tenfold when compared to the ratio of a fully perfused kidney. Results of monitoring blood acidosis by laser-induced fluorescence spectroscopy shows a significant trend between pH and intensity ratio. Since all the slopes were negative, there is an obvious significant correlation between the pH and NADH.COLLAGEN RATIO. Blue-light-induced fluorescence measurements and ratio fluorometry is a sensitive method for monitoring blood perfusion and acidity or alkalinity of an organ.

Vari, Sandor G.; Papazoglou, Theodore G.; Pergadia, Vani R.; Stavridi, Marigo; Snyder, Wendy J.; Papaioannou, Thanassis; Duffy, J. T.; Weiss, Andrew B.; Thomas, Reem; Grundfest, Warren S.

1994-01-01

204

CAD of myocardial perfusion  

NASA Astrophysics Data System (ADS)

Our purpose is in the automated evaluation of the physiological relevance of lesions in coronary angiograms. We aim to extract as much as possible quantitative information about the physiological condition of the heart from standard angiographic image sequences. Coronary angiography is still the gold standard for evaluating and diagnosing coronary abnormalities as it is able to locate precisely the coronary artery lesions. The dimensions of the stenosis can be assessed nowadays successfully with image processing based Quantitative Coronary Angiography (QCA) techniques. Our purpose is to assess the clinical relevance of the pertinent stenosis. We therefore analyze the myocardial perfusion as revealed in standard angiographic image sequences. In a Region-of-Interest (ROI) on the angiogram (without an overlaying major blood vessel) the contrast is measured as a function of time (the so-called time-density curve). The required hyperemic state of exercise is induced artificially by the injection of a vasodilator drug e.g. papaverine. In order to minimize motion artifacts we select based on the recorded ECG signal end-diastolic images in both a basal and a hyperemic run in the same projection to position the ROI. We present the development of the algorithms together with results of a small study of 20 patients which have been catheterized following the standard protocol.

Storm, Corstiaan J.; Slump, Cornelis H.

2007-03-01

205

Pretest Predictions for Ventilation Tests  

SciTech Connect

The objective of this calculation is to predict the temperatures of the ventilating air, waste package surface, concrete pipe walls, and insulation that will be developed during the ventilation tests involving various test conditions. The results will be used as input to the following three areas: (1) Decisions regarding testing set-up and performance. (2) Assessing how best to scale the test phenomena measured. (3) Validating numerical approach for modeling continuous ventilation. The scope of the calculation is to identify the physical mechanisms and parameters related to thermal response in the ventilation tests, and develop and describe numerical methods that can be used to calculate the effects of continuous ventilation. Sensitivity studies to assess the impact of variation of linear power densities (linear heat loads) and ventilation air flow rates are included. The calculation is limited to thermal effect only.

Y. Sun; H. Yang; H.N. Kalia

2007-01-17

206

Digital Compensation of IQ Imbalance for Dual-Carrier Double Conversion Receivers  

NASA Astrophysics Data System (ADS)

A receiver architecture and a digital IQ imbalance compensation method for dual-carrier reception are newly proposed. The impact of IQ imbalance on the baseband signal is mathematically analyzed. Based on the analysis, IQ imbalance parameters are estimated and the coupling effect of IQ imbalance is compensated using digital baseband processing alone. Simulation results show that the proposed IQ imbalance compensation successfully removes IQ imbalance. The deviation from the ideal performance is less than 1dB when it is applied to the 3GPP-LTE carrier aggregation.

Park, Chester Sungchung; Park, Fitzgerald Sungkyung

207

PERFORMANCE IMBALANCES IN THE CHAIN: EU TRADITIONAL FOOD SECTOR  

Microsoft Academic Search

Organizations nowadays no longer compete as independent entities, but as chains (Christopher, 1998; Cox, 1999; Lambert and Cooper, 2000). Hence, being part of a well-performing chain is crucial for the future of the individual food firm, especially in the context of the globalizing economy. As a result, the objective of this study is to identify performance imbalances of traditional food

Adrienn Molnar; Xavier Gellynck

2009-01-01

208

US–China external imbalance and the global financial crisis  

Microsoft Academic Search

This paper advances an alternative explanation of the large external imbalance between the United States and China, and its linkages to the current global financial crisis. We show that US current account deficits dated back long before the emergence of China's recent large trade surpluses, with China accounting at its peak for at most one-third of this deficit. The relative

Justin Yifu Lin; Hinh T. Dinh; Fernando Im

2010-01-01

209

Effects of imbalance and geometric error on precision grinding machines  

Microsoft Academic Search

To study balancing in grinding, a simple mechanical system was examined. It was essential to study such a well-defined system, as opposed to a large, complex system such as a machining center. The use of a compact, well-defined system enabled easy quantification of the imbalance force input, its phase angle to any geometric decentering, and good understanding of the machine

Bibler

1997-01-01

210

Current Account Imbalances in the Euro Area: A Comparative Perspective  

Microsoft Academic Search

This paper considers the increase in current account imbalances in euro area countries since the early 1990s. While the euro area as a whole has remained relatively close to external balance, the current account balances of individual countries have diverged: Spain, Greece and Portugal ran large current account deficits by historical norms for industrial economies, while Germany and the Netherlands

Sebastian Barnes; Jeremy Lawson; Artur Radziwill

2010-01-01

211

Resolving and Avoiding Unsustainable Imbalances in the Euro Area  

Microsoft Academic Search

Some euro area countries accumulated large and persistent external imbalances during the upswing, revealing important weaknesses in the macroeconomic management of the monetary union. Greece, Ireland, Portugal and Spain ran large current account deficits by historical standards, while Finland, Germany and the Netherlands had substantial surpluses. Some of these deficits and surpluses were larger than appear justified by economic fundamentals.

Sebastian Barnes

2010-01-01

212

Effect of Conductor Imbalance on Flexible Transmission Structures  

Microsoft Academic Search

Methods of determining longitudinal tensions to be supported by flexible transmission structures, such as tubular steel poles, A frames, H frames, and similar two-dimensional structures, as a result of phase severance, or similar imbalance in one span of a series, are outlined. Tension reduction caused by insulator displacement plus the consequent structure deflection is determined.

Jordan Lummis; Robert Fiss

1969-01-01

213

Do equilibrium constraints modulate postural reaction when viewing imbalance?  

PubMed

Action observation and action execution are tightly coupled on a neurophysiological and a behavioral level, such that visually perceiving an action can contaminate simultaneous and subsequent action execution. More specifically, observing a model in postural disequilibrium was shown to induce an increase in observers' body sway. Here we reciprocally questioned the role of observers' motor system in the contagion process by comparing participants' body sway when watching displays of antero-posterior vs. lateral imbalance. Indeed, during upright standing, biomechanical constraints differ along the antero-posterior (A-P) and medio-lateral (M-L) axes; hence an impact of observers' postural constraints on the contagion response would result in different reactions to both types of stimuli. In response to the displays, we recorded greater area of center of pressure (CoP) displacement when watching forward/backward compared to left/right imbalance. In addition, after normalizing A-P and M-L CoP displacements by a control condition (fixation cross), A-P CoP path length when viewing forward imbalance tended to be higher than M-L CoP path length when viewing imbalance to the left or right. These results indicate that postural contagion is promoted when the display is compatible with observers' motor stabilization strategy which is mainly oriented along the A-P axis. In terms of clinical application, this study brings new indications for adaptation of observational training devices in rehabilitation programs. PMID:22466502

Tia, Banty; Paizis, Christos; Mourey, France; Pozzo, Thierry

2012-03-30

214

Methionine imbalance and toxicity in calves1,2  

Microsoft Academic Search

The occurrence of methionine imbal- ance and toxicity was examined using 70- and 100-kg Holstein bull calves. The animals had been trained to maintain reflex closure of the reticular groove after weaning at 5 wk of age, and Trials 1 (n = 30) and 2 (n = 24) were conducted on animals at 7 and 12 wk of age, respectively.

M. Abe; H. Okada; D. Matsumura; H. Sato; M. Funaba; T. Iriki

215

MR Perfusion Imaging in Acute Ischemic Stroke  

PubMed Central

MR perfusion imaging offers the potential for measuring brain perfusion in acute stroke patients, at a time when treatment decisions based upon these measurements may affect outcomes dramatically. Rapid advancements in both acute stroke therapy and perfusion imaging techniques have resulted in continuing redefinition of the role that perfusion imaging should play in patient management. This review first discusses the basic pathophysiology of acute stroke, with specific attention to alterations in the various perfusion-related parameters that can be studied by MR perfusion imaging. Although these parameters are sometimes treated as somewhat interchangeable, they reveal greatly different information about brain perfusion. Therefore, subsequent discussion of the utility of different kinds of perfusion images focuses on the differences between them, as well as important artifacts that can complicate their interpretation. Finally, research on the continually evolving role of MR perfusion imaging in acute stroke care is summarized.

Copen, William A.; Schaefer, Pamela W.; Wu, Ona

2011-01-01

216

Ventilation in chest trauma  

PubMed Central

Chest trauma is one important factor for total morbidity and mortality in traumatized emergency patients. The complexity of injury in trauma patients makes it challenging to provide an optimal oxygenation while protecting the lung from further ventilator-induced injury to it. On the other hand, lung trauma needs to be treated on an individual basis, depending on the magnitude, location and type of lung or chest injury. Several aspects of ventilatory management in emergency patients are summarized herein and may give the clinician an overview of the treatment possibilities for chest trauma victims.

Richter, Torsten; Ragaller, Maximilian

2011-01-01

217

Cadmium transport and toxicity in isolated perfused renal proximal tubules  

SciTech Connect

Cadmium is a potent toxicant preferentially accumulated in the renal cortex of humans and other animals. To assess the renal toxicity of inorganic cadmium, isolated segments (S1, S2, and S3) of rabbit renal proximal tubules were perfused with various concentrations of unlabeled cadmium chloride (CdCl[sub 2]) and a vital dye (FD C green). The tubular epithelial cells were observed under the light microscope for cellular injury and necrosis. Cellular swelling, luminal membrane blebbing, and cellular vacuolization were indicators of cellular injury, and dye uptake was indicative of cellular necrosis. To determine lumen-to-bath transport rates for cadmium, the segments were perfused with a mixture of [sup 109]CdCl[sub 2] and [sup 3]H-L-glucose; unlabeled CdCl[sub 2] was added when necessary to vary the total cadmium concentration from 1.5 [mu]M to 2000 [mu]M. Immediately after perfusion the tubules were extracted with 3% trichoroacetic acid (TCA) or with a modified Ringer's buffer of reduced osmolality to determine the fate of the cadmium removed from the lumen. Based on the toxicant indicators, increased dye uptake, increased luminal membrane blebbing, and increased vacuole formation, as the cadmium concentration was increased, cadmium was found to show toxicity to renal tubular cells at concentrations greater than 500 [mu]M. In transport experiments, increasing the cadmium concentration causes an increase in the leak of L-glucose, also indicating toxicity. A clear imbalance exists between the rate of disappearance of cadmium from the lumen and the rate of appearance in the bath for all three tubular segments. Cadmium appears to bind cellular membrane proteins, but it is extractable with 3% TCA. Cadmium, like mercury, is taken up at the luminal membrane, but very little is transported through the basolateral membrane.

Robinson, M.E.K.

1991-01-01

218

Ventilation Host and Risk Area Techniques.  

National Technical Information Service (NTIS)

This study consisted of an investigation into several aspects of providing ventilation in counterforce risk- and host-area shelter facilities. Ventilation concepts, including the characteristics of methods for providing ventilation and the shelter charact...

S. B. York R. J. Reeves R. J. Wallace

1982-01-01

219

30 CFR 75.333 - Ventilation controls.  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 2010-07-01 false Ventilation controls. 75.333 Section 75.333 ...MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.333 Ventilation controls. (a) For purposes of this...

2010-07-01

220

30 CFR 57.8520 - Ventilation plan.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Ventilation plan. 57.8520 Section 57.8520...STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Underground Only § 57.8520 Ventilation plan. A plan of the mine...

2009-07-01

221

[Assisted ventilation at home].  

PubMed

In patients with chronic respiratory failure, in particular in those with accompanying wall-dependent restrictive syndrome (i.e. kyphoscoliosis, certain myopathies...) shortness of breath and sequelae of cor pulmonale usually limit quality of life distinctly. In particular repeated hospitalizations necessitated by remittent occurrence of severe respiratory decompensation, usually in the course of infections, reduce life quality and life expectancy. Thus, selected patients may benefit remarkably from a device for assisted ventilation at home as a technical measure with good results. The number of hospitalizations is markedly reduced, shortness of breath can even disappear completely, so that patients can regain social activity. The usually non-invasive technique (ventilation with nose-mask) is applied at night, so that disturbance is low for the patient and his surroundings. It is however necessary, that his financial burden and technical maintenance and servicing of materials is granted by an organisation, who is also able to provide safety for the patient and his family on a long term. PMID:8506437

Chevrolet, J C

1993-05-11

222

New Ventilated Isolation Cage  

PubMed Central

A multifunction lid has been developed for a commercially available transparent animal cage which permits feeding, watering, viewing, long-term holding, and local transport of laboratory rodents on experiment while isolating the surrounding environment. The cage is airtight except for its inlet and exhaust high-efficiency particulate air filters, and it is completely steam-sterilizable. Opening of the cage's feed and water ports causes an inrush of high velocity air which prevents back-migration of aerosols and permits feeding and watering while eliminating need for chemical vapor decontamination. Ventilation system design permits the holding in adjacent cages of animals infected with different organisms without danger of cross-contamination; leaves the animal room odor-free; reduces required bedding changes to twice a month or less, and provides investigators with capability to control precisely individual cage ventilation rates. Forty-eight cages can be conveniently placed on a standard NIH “shoebox” cage rack (60 inches wide × 28 inches deep × 74 inches high) fitted with a simple manifold exhaust system. The entire system is mobile, requiring only an electrical power outlet. Principal application of the caging system is in the area of preventing exposure of animal caretakers to pathogenic substances associated with the animal host, and in reducing handling of animals and their exposure to extraneous contamination. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 9

Cook, Reginald O.

1968-01-01

223

Emplacement Ventilation System  

SciTech Connect

The purpose of this analysis is to identify conceptual design options for the emplacement ventilation system, specifically within the emplacement drifts. The designs are based on the Enhanced Design Alternative (EDA) II concept developed during the license application design selection exercise as described in the ''License Application Design Selection Report'' (CRWMS M&O 1999a) and in the emplacement drift ''Ventilation Model'' (CRWMS M&O 2000c). The scope of this analysis, as outlined in the development plan (CRWMS M&O 2000a), includes the following tasks: (1) Description of the air flow path in the emplacement drifts. (2) Examination of the exhaust options for air exiting the emplacement drifts. (3) Examination of the air control options in the emplacement drifts. (4) Discussion of following system components and structures: emplacement isolation doors, portable shadow shield and exhaust main partition. The objective of this analysis is to support site recommendation through input to the system description documents. Off-normal conditions are not discussed in this analysis.

R. Vance

2000-04-05

224

Assessment of regional ventilation by continuous inhalation of radioactive krypton-81m  

Microsoft Academic Search

A simple technique is described for producing high-quality functional images of regional ventilation during physiological tidal breathing of the inert gas 81mKr. These images are quickly obtained on a gamma-camera without the need of computerized systems for data acquisition and display and are directly comparable with those of perfusion obtained with 99mTc-labelled macroaggregates. The short time required for the procedure,

F Fazio; T Jones

1975-01-01

225

Where to perform noninvasive ventilation?  

Microsoft Academic Search

Where to perform noninvasive ventilation? M.W. Elliott, M. Confalonieri, S. Nava. #ERS Journals Ltd 2002. ABSTRACT: Noninvasive positive-pressure ventilation (NPPV) has been shown to be a means of reducing the need for endotracheal intubation, which when effective reduces the complication rate and improves outcome. Because paralysis and sedation are not needed and because the patient is not necessarily dependent upon

M. W. Elliott; M. Confalonieri; S. Nava

2002-01-01

226

Ventilation system with spiral recuperator  

Microsoft Academic Search

A new kind of longitudinal flow spiral recuperator for the heat recovery in ventilation systems of buildings was studied experimentally and analytically.The aim of this work is to analyze the possibility of using air handling units with new type of spiral recuperator in order to recover heat in ventilation systems of buildings. For the reason that the air flows are

Mariusz Adamski

2010-01-01

227

Recent advances in mechanical ventilation  

Microsoft Academic Search

Important advances have been made over the past decade towards understanding the optimal approach to ventilating patients with acute respiratory failure. Evidence now supports the use of noninvasive positive pressure ventilation in selected patients with hypercapnic respiratory failure and chronic obstructive pulmonary disease, cardiogenic pulmonary edema, and for facilitating the discontinuation of ventilatory support in patients with chronic pulmonary disease.

Carolyn S. Calfee; Michael A. Matthay

2005-01-01

228

Home ventilation in Northern Ireland.  

PubMed Central

Thirteen patients were identified as receiving assisted ventilation at home in Northern Ireland in 1994. Two patients have since died. An increasing number of patients are starting home ventilation, especially by nasal mask. Recognition of the needs of these patients and provision of care require further consideration.

Nugent, A. M.; Lyons, J. D.; Gleadhill, I. C.; MacMahon, J.

1996-01-01

229

Recent updates in mechanical ventilation  

PubMed Central

Recently, several studies have been performed to better outline the pathophysiology of acute respiratory failure and evaluate the therapeutic profile of different modes of ventilation and ventilator settings. Here we briefly report those we consider most relevant for daily intensive care unit clinical practice.

Bergamaschi, Valentina

2009-01-01

230

Hepatic Blood Perfusion Estimated by Dynamic Contrast-Enhanced Computed Tomography in Pigs Limitations of the Slope Method  

PubMed Central

Objective To determine whether dynamic contrast-enhanced computed tomography (DCE-CT) and the slope method can provide absolute measures of hepatic blood perfusion from hepatic artery (HA) and portal vein (PV) at experimentally varied blood flow rates. Materials and Methods Ten anesthetized 40-kg pigs underwent DCE-CT during periods of normocapnia (normal flow), hypocapnia (decreased flow), and hypercapnia (increased flow), which was induced by adjusting the ventilation. Reference blood flows in HA and PV were measured continuously by surgically-placed ultrasound transit-time flowmeters. For each capnic condition, the DCE-CT estimated absolute hepatic blood perfusion from HA and PV were calculated using the slope method and compared with flowmeter based absolute measurements of hepatic perfusions and relative errors were analyzed. Results The relative errors (mean±SEM) of the DCE-CT based perfusion estimates were ?21±23% for HA and 81±31% for PV (normocapnia), 9±23% for HA and 92±42% for PV (hypocapnia), and 64±28% for HA and ?2±20% for PV (hypercapnia). The mean relative errors for HA were not significantly different from zero during hypo- and normocapnia, and the DCE-CT slope method could detect relative changes in HA perfusion between scans. Infusion of contrast agent led to significantly increased hepatic blood perfusion, which biased the PV perfusion estimates. Conclusions Using the DCE-CT slope method, HA perfusion estimates were accurate at low and normal flow rates whereas PV perfusion estimates were inaccurate and imprecise. At high flow rate, both HA perfusion estimates were significantly biased.

Winterdahl, Michael; S?rensen, Michael; Keiding, Susanne; Mortensen, Frank V.; Alstrup, Aage K. O.; Hansen, S?ren B.; Munk, Ole L.

2012-01-01

231

Tc-/sup 99m/-DTPA aerosol and radioactive gases compared as adjuncts to perfusion scintigraphy in patients with suspected pulmonary embolism  

SciTech Connect

To evaluate the clinical utility of improved methods for radioaerosol inhalation imaging, we obtained preperfusion radioaerosol images in 107 patients (mean age . 62 years), who were referred for evaluation of suspected pulmonary embolism (PE). For each patient, we compared six-view aerosol images with accompanying perfusion scans and chest radiographs and with Xenon-133 (Xe-133) or Krypton-81m (Kr-81m) studies. Four observers at four different institutions independently evaluated aerosol-perfusion and gas-perfusion pairs, classifying the probability of PE as low, high, or indeterminate. The radioaerosol images were good to excellent in quality; excessive central deposition of activity was infrequent and did not interfere with image interpretation. The aerosol-perfusion studies showed 86% agreement with Xe-133 perfusion interpretations (n . 299) and 80% agreement with Kr-81m perfusion interpretations (n . 99). These rates of agreement were comparable with those of intraobserver agreement for gas-to-gas and aerosol-to-aerosol comparisons, and higher than interobserver agreement rates. In a limited number (n . 9) of angiographically documented cases, aerosol-perfusion and gas-perfusion studies provided accurate and equivalent diagnoses. The results suggest that radioaerosol inhalation studies, performed with improved nebulizers, are diagnostically equivalent to ventilation imaging as an adjunct to perfusion scintigraphy in evaluating patients with suspected PE.

Alderson, P.O.; Biello, D.R.; Gottschalk, A.; Hoffer, P.B.; Kroop, S.A.; Lee, M.E.; Ramanna, L.; Siegel, B.A.; Waxman, A.D.

1984-11-01

232

Retrograde heart perfusion: the Langendorff technique of isolated heart perfusion.  

PubMed

In the late 19th century, a number of investigators were working on perfecting isolated heart model, but it was Oscar Langendorff who, in 1895, pioneered the isolated perfused mammalian heart. Since that time, the Langendorff preparation has evolved and provided a wealth of data underpinning our understanding of the fundamental physiology of the heart: its contractile function, coronary blood flow regulation and cardiac metabolism. In more recent times, the procedure has been used to probe pathophysiology of ischaemia/reperfusion and disease states, and with the dawn of molecular biology and genetic manipulation, the Langendorff perfused heart has remained a stalwart tool in the study of the impact upon the physiology of the heart by pharmacological inhibitors and targeted deletion or up-regulation of genes and their impact upon intracellular signalling and adaption to clinically relevant stressful stimuli. We present here the basic structure of the Langendorff system and the fundamental experimental rules which warrant a viable heart preparation. In addition, we discuss the use of the isolated retrograde perfused heart in the model of ischaemia-reperfusion injury ex-vivo, and its applicability to other areas of study. The Langendorff perfusion apparatus is highly adaptable and this is reflected not only in the procedure's longevity but also in the number of different applications to which it has been turned. PMID:21385587

Bell, Robert M; Mocanu, Mihaela M; Yellon, Derek M

2011-03-06

233

How does Chinese medicine target cytokine imbalance in rheumatoid arthritis?  

PubMed

Rheumatoid arthritis (RA) manifests as an imbalance between pro- and anti-inflammatory cytokines. Cytokine imbalance is suggested to play critical roles in the development of RA. Currently, various treatments for RA, including biological agents such as antibodies against inflammation mediators, or Chinese herbal medicines, intervene the disease by restoring the balance of cytokines. Chinese medicine (CM) can not only suppress the expression of pro-inflammatory cytokines, but also induce the expression of cytokines with anti-inflammatory and immunomodulatory effects. Thus, Chinese medicine can effectively reduce inflammatory cell infiltration into synovial tissue, pannus formation, and degradation of the extracellular matrix surrounding cartilage cells, thereby reducing subchondral bone damage. This paper reviews the changes of cytokine profiling during development of RA and discuss the mechanisms by which Chinese medicine restores the cytokine balance. PMID:24170633

Liu, Jian; Sun, Yue

2013-10-30

234

Causes of imbalance and abnormal gait that may be misdiagnosed.  

PubMed

Disorders of gait and balance are common in medicine and often lead to referral for neurologic evaluation. Because the maintenance of balance and normal gait are mediated by complex neurologic pathways as well as musculoskeletal, metabolic, and behavioral considerations, the list of possible contributing causes is very large. Much of the time, the history and neurologic examination reveal the underlying cause or causes. There are instances, however, when there are limited neurologic findings, as well as no structural abnormalities on brain or spine magnetic resonance imaging studies to explain the imbalance or gait difficulty. In this article, selected disorders that may be overlooked in the neurologic examination and imaging studies are reviewed. Possible causes of imbalance include occult drug-induced ataxia, autoimmune ataxia, ataxia associated with tremor, bilateral vestibular hypofunction, and spastic or dystonic gait disorders with normal imaging. PMID:24057830

Shill, Holly A; Fife, Terry D

2013-09-21

235

[Mechanical ventilation in pediatrics (III). Weaning, complications and other types of ventilation. High-frequency ventilation].  

PubMed

In the era of lung-protective ventilation strategies, high frequency oscillatory ventilation (HFOV) has attracted renewed interest and its use has dramatically increased in neonatal and pediatric intensive care units. HFOV is able to reduce ventilator-induced lung injury by limiting the incidence of volutrauma, atelectrauma, barotrauma and biotrauma. During HFOV, adequate oxygenation and ventilation is achieved by using low tidal volumes and small pressure swings at supraphysiologic frequencies. Unlike other high-frequency ventilation modes, HFOV has an active expiration phase. HFOV constitutes a safe and successful ventilation mode for managing pediatric patients with respiratory insufficiency refractory to optimized conventional mechanical ventilation and provides better results when initiated early. However, the elective use of HFOV requires further studies to identify its benefits over conventional modes of mechanical ventilation and to support its routine use as a first line therapy. In the present article, the Respiratory Working Group of the Spanish Society Pediatric Critical Care reviews the main issues in the pediatric application of HFOV. In addition, a general practical protocol and specific management strategies, as well as the monitoring, patient care and other special features of the use of HFOV in the pediatric setting, are discussed. PMID:14562843

Martinón-Torres, F; Ibarra de la Rosa, I; Fernández Sanmartín, M; García Menor, E; Marinón Sánchez, J M

2003-08-01

236

Chronic cholinergic imbalances promote brain diffusion and transport abnormalities  

Microsoft Academic Search

Cholinergic imbalances occur after traumatic effects and in the initial stages of neuro- degenerative diseases, but their long-lasting effects remained largely unexplained. To address this, we used TgS transgenic mice constitutively overexpress- ing synaptic acetylcholinesterase (AChE-S) and pre- senting a complex phenotype of progressive neuro- deterioration. T1- and T2-weighted magnetic resonance (MR) brain images appeared similar. How- ever, diffusion-weighted MRI

Eran Meshorer; Inbal E. Biton; Yoram Ben-Shaul; Shani Ben-Ari; Yaniv Assaf; Hermona Soreq; Yoram Cohen

2005-01-01

237

Compensation of IQ imbalance and phase noise in OFDM systems  

Microsoft Academic Search

Nowadays, a lot of effort is spent on developing inexpensive orthogonal frequency-division multiplexing (OFDM) receivers. Especially, zero intermediate frequency (zero-IF) receivers are very appealing, because they avoid costly IF filters. However, zero-IF front-ends also introduce significant additional front-end distortion, such as IQ imbalance. Moreover, zero-IF does not solve the phase noise problem. Unfortunately, OFDM is very sensitive to the receiver

Jan Tubbax; Boris Côme; Liesbet Van Der Perre; Stéphane Donnay; Marc Engels; Hugo De Man; Marc Moonen

2005-01-01

238

MMSE WL Equalizer in Presence of Receiver IQ Imbalance  

Microsoft Academic Search

In this correspondence, with reference to the transmission over a linear time-dispersive channel, we address the problem of the in-phase and quadrature-phase (IQ) imbalance compensation when a single-carrier modulation scheme is used. Low-cost fabrication technologies and high data-rate transmissions render the conventional receivers very sensitive to the imperfections of their analog stage and, hence, proper countermeasures need to be adopted.

Davide Mattera; Luigi Paura; Fabio Sterle

2008-01-01

239

Partial liquid ventilation.  

PubMed

Mortality from the adult respiratory distress syndrome (ARDS) and the infant respiratory distress syndrome remains high despite numerous interventions and modalities. Perfluorocarbons (PFC) are inert liquids that can dissolve large amounts of oxygen and carbon dioxide and can be used as respiratory media. Partial liquid ventilation uses PFC to partially fill the lungs of patients with ARDS to improve gas exchange and support them. Studies in animals and humans (mostly neonates) using perflubron, which is currently the only PFC approved for clinical use, have shown that they are safe and effective in improving oxygenation. In this article the rationale of the technique, its historical background, and animal and clinical data to date are reviewed. PMID:16088730

Hadjiliadis, D

2000-01-01

240

Flux emergence, flux imbalance, magnetic free energy and solar flares  

NASA Astrophysics Data System (ADS)

Emergence of complex magnetic flux in the solar active regions lead to several observational effects such as a change in sunspot area and flux embalance in photospheric magnetograms. The flux emergence also results in twisted magnetic field lines that add to free energy content. The magnetic field configuration of these active regions relax to near potential-field configuration after energy release through solar flares and coronal mass ejections. In this paper, we study the relation of flare productivity of active regions with their evolution of magnetic flux emergence, flux imbalance and free energy content. We use the sunspot area and number for flux emergence study as they contain most of the concentrated magnetic flux in the active region. The magnetic flux imbalance and the free energy are estimated using the HMI/SDO magnetograms and Virial theorem method. We find that the active regions that undergo large changes in sunspot area are most flare productive. The active regions become flary when the free energy content exceeds 50% of the total energy. Although, the flary active regions show magnetic flux imbalance, it is hard to predict flare activity based on this parameter alone.

Choudhary, Debi Prasad; Gosain, Sanjay; Gopalswamy, Nat; Manoharan, P. K.; Chandra, R.; Uddin, W.; Srivastava, A. K.; Yashiro, S.; Joshi, N. C.; Kayshap, P.; Dwivedi, V. C.; Mahalakshmi, K.; Elamathi, E.; Norris, Max; Awasthi, A. K.; Jain, R.

2013-10-01

241

46 CFR 153.312 - Ventilation system standards.  

Code of Federal Regulations, 2012 CFR

...ft) from openings into or ventilation intakes for, accommodation or service spaces. (b) A ventilation system must not recycle vapors from ventilation discharges. (c) Except for the space served by the ventilation duct, a ventilation duct...

2012-10-01

242

46 CFR 153.312 - Ventilation system standards.  

Code of Federal Regulations, 2011 CFR

...ft) from openings into or ventilation intakes for, accommodation or service spaces. (b) A ventilation system must not recycle vapors from ventilation discharges. (c) Except for the space served by the ventilation duct, a ventilation duct...

2011-10-01

243

Kinetics of reversible-sequestration of leukocytes by the isolated perfused rat lung  

SciTech Connect

The kinetics and morphology of sequestration and margination of rat leukocytes were studied using an isolated perfused and ventilated rat lung preparation. Whole rat blood, bone marrow suspension, or leukocyte suspensions, were used to perfuse the isolated rat lung. The lung was also perfused with latex particle suspensions and the passage of particles through the lung capillaries was studied. When a leukocyte suspension was perfused through the lung in the single-pass mode, the rate of sequestration decreased as more cells were perfused. In contrast, latex particles of a size comparable to that of leukocytes were totally stopped by the lung. When the leukocyte suspension was recirculated through the lung, cells were rapidly removed from circulation until a steady state was reached, after which no net removal of cells by the lung occurred. These results indicate that leukocytes are reversibly sequestered from circulation. The sequestered cells marginated and attached to the luminal surface of the endothelium of post-capillary venules and veins. A mathematical model was developed based on the assumption that the attachment and detachment of leukocytes to blood vessel walls follows first-order kinetics. The model correctly predicts the following characteristics of the system: (a) the kinetics of the sequestration of leukocytes by the lung; (b) the existence of a steady state when a suspension of leukocytes is recirculated through the lung; and (c) the independence of the fraction of cells remaining in circulation from the starting concentration for all values of starting concentration. (ERB)

Goliaei, B.

1980-08-01

244

Myocardial perfusion scintigraphy: the evidence  

Microsoft Academic Search

This review summarises the evidence for the role of myocardial perfusion scintigraphy (MPS) in patients with known or suspected coronary artery disease. It is the product of a consensus conference organised by the British Cardiac Society, the British Nuclear Cardiology Society and the British Nuclear Medicine Society and is endorsed by the Royal College of Physicians of London and the

S. R. Underwood; C. Anagnostopoulos; M. Cerqueira; P. J. Ell; E. J. Flint; M. Harbinson; A. D. Kelion; A. Al-Mohammad; E. M. Prvulovich; L. J. Shaw; A. C. Tweddel

2004-01-01

245

Subsurface Ventilation System Description Document  

SciTech Connect

The Subsurface Ventilation System supports the construction and operation of the subsurface repository by providing air for personnel and equipment and temperature control for the underground areas. Although the system is located underground, some equipment and features may be housed or located above ground. The system ventilates the underground by providing ambient air from the surface throughout the subsurface development and emplacement areas. The system provides fresh air for a safe work environment and supports potential retrieval operations by ventilating and cooling emplacement drifts. The system maintains compliance within the limits established for approved air quality standards. The system maintains separate ventilation between the development and waste emplacement areas. The system shall remove a portion of the heat generated by the waste packages during preclosure to support thermal goals. The system provides temperature control by reducing drift temperature to support potential retrieval operations. The ventilation system has the capability to ventilate selected drifts during emplacement and retrieval operations. The Subsurface Facility System is the main interface with the Subsurface Ventilation System. The location of the ducting, seals, filters, fans, emplacement doors, regulators, and electronic controls are within the envelope created by the Ground Control System in the Subsurface Facility System. The Subsurface Ventilation System also interfaces with the Subsurface Electrical System for power, the Monitored Geologic Repository Operations Monitoring and Control System to ensure proper and safe operation, the Safeguards and Security System for access to the emplacement drifts, the Subsurface Fire Protection System for fire safety, the Emplacement Drift System for repository performance, and the Backfill Emplacement and Subsurface Excavation Systems to support ventilation needs.

NONE

2000-10-12

246

Subsurface Ventilation System Description Document  

SciTech Connect

The Subsurface Ventilation System supports the construction and operation of the subsurface repository by providing air for personnel and equipment and temperature control for the underground areas. Although the system is located underground, some equipment and features may be housed or located above ground. The system ventilates the underground by providing ambient air from the surface throughout the subsurface development and emplacement areas. The system provides fresh air for a safe work environment and supports potential retrieval operations by ventilating and cooling emplacement drifts. The system maintains compliance within the limits established for approved air quality standards. The system maintains separate ventilation between the development and waste emplacement areas. The system shall remove a portion of the heat generated by the waste packages during preclosure to support thermal goals. The system provides temperature control by reducing drift temperature to support potential retrieval operations. The ventilation system has the capability to ventilate selected drifts during emplacement and retrieval operations. The Subsurface Facility System is the main interface with the Subsurface Ventilation System. The location of the ducting, seals, filters, fans, emplacement doors, regulators, and electronic controls are within the envelope created by the Ground Control System in the Subsurface Facility System. The Subsurface Ventilation System also interfaces with the Subsurface Electrical System for power, the Monitored Geologic Repository Operations Monitoring and Control System to ensure proper and safe operation, the Safeguards and Security System for access to the emplacement drifts, the Subsurface Fire Protection System for fire safety, the Emplacement Drift System for repository performance, and the Backfill Emplacement and Subsurface Excavation Systems to support ventilation needs.

Eric Loros

2001-07-25

247

[Ventilator associated acute lung injury].  

PubMed

Mechanical ventilation plays a central role in the critical care setting; but its use is closely related with some life threatening complications as nosocomial pneumonia and low cardiac performance. One of the most severe complications is called ventilator-associated lung injury (VALI) and it includes: Barotrauma, volutrauma, atelectrauma, biotrauma and oxygen-mediated toxic effects and it is related with an inflammatory response secondary to the stretching and recruitment process of alveoli within mechanical ventilation. The use of some protective ventilatory strategies has lowered the mortality rate 10% approximately. PMID:16187708

Namendys-Silva, Silvio Antonio; Posadas-Calleja, Juan Gabriel

248

Energy Analysis of Ventilated Roof  

Microsoft Academic Search

\\u000a The thermal performance of the building envelope is an important requirement for guaranteeing both a comfortable indoor climate\\u000a and building’s energy efficiency.\\u000a \\u000a \\u000a Ventilated facades and ventilated roofs could be considered as a passive cooling system that contribute to realize low energy\\u000a building.\\u000a \\u000a \\u000a \\u000a The energy advantages provided by the ventilation of structures, during the summer, is the reduction of the cooling

F. Patania; A. Gagliano; F. Nocera; A. Ferlito; A. Galesi

249

Mechanical ventilation of the premature neonate.  

PubMed

Although the trend in the neonatal intensive care unit is to use noninvasive ventilation whenever possible, invasive ventilation is still often necessary for supporting pre-term neonates with lung disease. Many different ventilation modes and ventilation strategies are available to assist with the optimization of mechanical ventilation and prevention of ventilator-induced lung injury. Patient-triggered ventilation is favored over machine-triggered forms of invasive ventilation for improving gas exchange and patient-ventilator interaction. However, no studies have shown that patient-triggered ventilation improves mortality or morbidity in premature neonates. A promising new form of patient-triggered ventilation, neurally adjusted ventilatory assist (NAVA), was recently FDA approved for invasive and noninvasive ventilation. Clinical trials are underway to evaluate outcomes in neonates who receive NAVA. New evidence suggests that volume-targeted ventilation modes (ie, volume control or pressure control with adaptive targeting) may provide better lung protection than traditional pressure control modes. Several volume-targeted modes that provide accurate tidal volume delivery in the face of a large endotracheal tube leak were recently introduced to the clinical setting. There is ongoing debate about whether neonates should be managed invasively with high-frequency ventilation or conventional ventilation at birth. The majority of clinical trials performed to date have compared high-frequency ventilation to pressure control modes. Future trials with premature neonates should compare high-frequency ventilation to conventional ventilation with volume-targeted modes. Over the last decade many new promising approaches to lung-protective ventilation have evolved. The key to protecting the neonatal lung during mechanical ventilation is optimizing lung volume and limiting excessive lung expansion, by applying appropriate PEEP and using shorter inspiratory time, smaller tidal volume (4-6 mL/kg), and permissive hypercapnia. This paper reviews new and established neonatal ventilation modes and strategies and evaluates their impact on neonatal outcomes. PMID:21944682

Brown, Melissa K; DiBlasi, Robert M

2011-09-01

250

Ventilator-delivered mask ventilation compared with three standard methods of mask ventilation in a manikin model  

Microsoft Academic Search

BackgroundLittle is known regarding the variations in effective ventilation during bag and mask resuscitation with standard methods compared with that delivered by ventilator-delivered mask ventilation (VDMV).AimTo measure the variations in delivered airway pressure, tidal volume (TV), minute ventilation (MV) and inspiratory time during a 3-min period of mask ventilation comparing VDMV with three commonly used hand-delivered methods of bag and

M. B. Tracy; J. Klimek; H. Coughtrey; V. Shingde; G. Ponnampalam; M. Hinder; R. Maheshwari; S. K. Tracy

2011-01-01

251

Preoperational test, vent building ventilation system  

SciTech Connect

Preoperational Test Procedure for Vent Building Ventilation System, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The Vent Building ventilation system provides ventilation, heating, cooling, and zone confinement control for the W-030 Project Vent Building. The tests verify correct System operation and correct indications displayed by the central Monitor and Control system.

Clifton, F.T., Westinghouse Hanford

1996-08-20

252

Use of Adaptive Support Ventilation (ASV) in Ventilator Associated Pneumonia (VAP) - A Case Report  

PubMed Central

Summary Prolonged ventilation leads to a higher incidence of ventilator associated pneumonia(VAP) resulting in ventilator dependency, increased costs and subsequent weaning failures. Prevention and aggressive treatment of VAP along with patient friendly newer modes of ventilation like adaptive support ventilation go a long way in successful management of these cases.

Kath, Bipphy; Hemanth, N; Marella, Prashanti; Rao, M H

2009-01-01

253

Equivalence in Ventilation and Indoor Air Quality  

SciTech Connect

We ventilate buildings to provide acceptable indoor air quality (IAQ). Ventilation standards (such as American Society of Heating, Refrigerating, and Air-Conditioning Enginners [ASHRAE] Standard 62) specify minimum ventilation rates without taking into account the impact of those rates on IAQ. Innovative ventilation management is often a desirable element of reducing energy consumption or improving IAQ or comfort. Variable ventilation is one innovative strategy. To use variable ventilation in a way that meets standards, it is necessary to have a method for determining equivalence in terms of either ventilation or indoor air quality. This study develops methods to calculate either equivalent ventilation or equivalent IAQ. We demonstrate that equivalent ventilation can be used as the basis for dynamic ventilation control, reducing peak load and infiltration of outdoor contaminants. We also show that equivalent IAQ could allow some contaminants to exceed current standards if other contaminants are more stringently controlled.

Sherman, Max; Walker, Iain; Logue, Jennifer

2011-08-01

254

Ventilation Model and Analysis Report  

SciTech Connect

This model and analysis report develops, validates, and implements a conceptual model for heat transfer in and around a ventilated emplacement drift. This conceptual model includes thermal radiation between the waste package and the drift wall, convection from the waste package and drift wall surfaces into the flowing air, and conduction in the surrounding host rock. These heat transfer processes are coupled and vary both temporally and spatially, so numerical and analytical methods are used to implement the mathematical equations which describe the conceptual model. These numerical and analytical methods predict the transient response of the system, at the drift scale, in terms of spatially varying temperatures and ventilation efficiencies. The ventilation efficiency describes the effectiveness of the ventilation process in removing radionuclide decay heat from the drift environment. An alternative conceptual model is also developed which evaluates the influence of water and water vapor mass transport on the ventilation efficiency. These effects are described using analytical methods which bound the contribution of latent heat to the system, quantify the effects of varying degrees of host rock saturation (and hence host rock thermal conductivity) on the ventilation efficiency, and evaluate the effects of vapor and enhanced vapor diffusion on the host rock thermal conductivity.

V. Chipman

2003-07-18

255

The Imbalance of Water in Nature as System  

NASA Astrophysics Data System (ADS)

Consider some of the water-containing area. Choose some the factors which we consider important to the system. The system contains a system factors, and the external environment these factors doesn't contain. Between the system and the external environment must be some flows into the system, out of the system and along the border. If the flows into and out of the system are not equal, that means within the system exactly something is happening. But the equality of the flows into and out of the system does not mean that within the system nothing happens. It is extremely important to determine the time factor. Everything has a beginning and an end. Each factor has its own life from 0 to 1, as well as their watches. Thus that within the system and the environment at the same time are going a lot of the watches and each watch is going by their own pace. System-wide time is needed to describe the system as a whole and to be able to re-measure the individual time of each factor. It is also very important to identify each factor of the system, environment and border. Definition of each particular factor depends on the level of our knowledge. There are many examples where one factor was divided into several, and vice versa, several factors have combined in one or even disappear as a non-existent. Each factor is determined by specific people for reasons of convenience, the specific of tasks, the possible accuracy of measurement, available resources, etc. The development of the science and applications are going to the direction of the clearer separation of factors and the precision of their measurements. Now is extremely important to more clearly define the boundaries of systems, factors and the allowed accuracy of their measurements. With such a revision, many previously balanced situations become to the imbalance. There are many specific details for each case, but they do not change the basic approach described above. If not clearly resolved the questions listed above so will not be obtained any reliable results. For example, the real water arrival occurs in the modes of imbalances such as increasing or decreasing. Water departure also is some set of the several imbalance increase and decrease types. The processes with various orientations interact between each other and reinforce or depress the conjoint effect. This creates some unstable situation, which are not visible by the balanced approach. Therefore some natural disasters actually are coming as unexpected. But in really there are some consequences of the methodological blindness. The Nature is unstable. The imbalance is the main state of the Nature. But mankind does not yet have adequate tools to describing imbalance as it is. In generally now is used more or less successful extrapolation and interpolation of the balance logic. But this is not enough now. So we tried to sharpen here the importance of the works with the imbalance directly.

Kontar, V. A.; Imbalance of Water in Nature

2011-12-01

256

THE COMPARISON OF MUSCLE FORCE IMBALANCE IN PROWERLIFTERS AND JUMPERS.  

PubMed

The purpose of the study was to examine the bilateral and unilateral force production difference in powerlifters (bilateral) and field jumpers (unilateral) to determine the existence of leg dominance.Nineteen powerlifters (PL; n= 11) and field jumpers (J; n= 8) were included in the study. Five different no arm swing countermovement jumps were randomized for testing: 1) double leg; 2) dominant leg specified double leg jump; 3) non-dominant leg specified double leg jump; 4) dominant leg specified single leg jump; 5) non-dominant leg specified single leg jump. The force, velocity and power were collected via a forceplate. The Limb Symmetry Index (LSI% = (1- ND limb/ D limb)*100%) was calculated for force imbalance between the N and ND limb between PL and J. Based on the analysis, PL (M = 2.75%± 2.45) had a lower LSI (p < .05) than J (M=6.81%±5.16). The single leg jumps show a (p < .05) significantly higher force, power and a significantly lower velocity than double leg jump for both D and ND leg than double leg jump. Lastly, the ratio between bilateral and unilateral exercise for PL and J is 2.36:1.36 and 2.38:1, respectively.In summary, sports specific demands between PL and J may contribute to the occurrence of the imbalance force production between limbs. This phenomenon is important for the strength coach to acknowledge, to perform an appropriate strength balance test during the off-season, and to implement a training program to reduce the force disparity between limbs. Neglecting the development of force imbalance between limbs may predispose healthy players to injury. PMID:23591945

Luk, Hui-Ying; Winter, Christa; O'Neill, Elizabeth; Thompson, Brian A

2013-04-15

257

Bilateral arm power imbalance in swim bench exercise to exhaustion.  

PubMed

We examined the supposition that swimmers may exhibit an imbalance in bilateral arm power output during simulated swimming exercise. Ten competitive front crawl swimmers (5 males, 5 females; age 20.5+/-2.3 years; height 1.74+/-0.09 m; body mass 72.0+/-16.7 kg; 400 m freestyle swim time 278+/-20.5 s; mean +/- s) performed four incremental (10 W x min(-1)) swim ramp tests on a computer-interfaced biokinetic swim bench ergometer. External power output from each arm was measured continuously to exhaustion. The results showed that, throughout the course of the simulated swim, external power output clearly favoured the left arm (F1,9 = 12.5, P= 0.006). This was especially evident in the final 30 s to exhaustion, when 54.0+/-3.87% of external power output was derived from the left arm versus 46.0+/-3.87% from the right arm. The disparity in external power output was further highlighted when the participants were grouped into unilateral and bilateral breathers. Unilateral breathers (n = 5) produced 57.1+/-2.62% of external power output from the left armversus 42.9+/-2.62% from the right arm (P= 0.001). Bilateral breathers (n = 5) exhibited a more balanced external power output of 51.0+/-1.82% from the left arm and 49.0+/-1.82% from the right arm (P = 0.177). Evidence of power imbalance in the simulated swimming stroke may have important implications for optimizing swim performance. The observed power imbalance may be reduced when a bilateral breathing technique is adopted. PMID:12477007

Potts, A D; Charlton, J E; Smith, H M

2002-12-01

258

New Energy-Saving Type of Ventilation for Loom Workshop  

Microsoft Academic Search

A new energy-saving type of ventilation named large and small zone ventilation for loom workshop is proposed in this paper. Large and small zone ventilation means there are two ventilation systems for loom workshop, where large zone ventilation for total loom workshop and small zone ventilation for loom surface is used. Large zone ventilation is mainly used to keep temperature

Zhu Caixia; Zhao Nannan; Gao Long; Song Gaoju

2009-01-01

259

Experimental Proteolytic Emphysema and the Lung Function. (Experiments with Dogs).  

National Technical Information Service (NTIS)

Inhalation of papain was found to cause emphysema of the lung in dogs and other animals. Following morphological changes, ventilation/perfusion imbalance with arterial hypoxia developed. An increase was observed in lung compliance and in the sensitivity o...

M. S. Islam G. Konn W. P. Oellig W. T. Ulmer W. Weller

1974-01-01

260

High frequency jet ventilation and intermittent positive pressure ventilation. Effect of cerebral blood flow in patients after open heart surgery  

SciTech Connect

Attenuation of ventilator-synchronous pressure fluctuations of intracranial pressure has been demonstrated during high frequency ventilation in animal and human studies, but the consequences of this effect on cerebral blood flow have not been investigated in man. We compared the effects of high frequency jet ventilation and intermittent positive pressure ventilation on CBF in 24 patients investigated three hours after completion of open-heart surgery. The patients were investigated during three consecutive periods with standard sedation (morphine, pancuronium): a. IPPV; b. HFJV; c. IPPV. Partial pressure of arterial CO{sub 2} (PaCO{sub 2}: 4.5-5.5 kPa) and rectal temperature (35.5 to 37.5{degree}C) were maintained constant during the study. The CBF was measured by intravenous {sup 133}Xe washout technique. The following variables were derived from the cerebral clearance of {sup 133}Xe: the rapid compartment flow, the initial slope index, ie, a combination of the rapid and the slow compartment flows, and the ratio of fast compartment flow over total CBF (FF). Compared to IPPV, HFJV applied to result in the same mean airway pressure did not produce any change in pulmonary gas exchange, mean systemic arterial pressure, and cardiac index. Similarly, CBF was not significantly altered by HFJV. However, important variations of CBF values were observed in three patients, although the classic main determinants of CBF (PaCO{sub 2}, cerebral perfusion pressure, Paw, temperature) remained unchanged. Our results suggest that in patients with normal systemic hemodynamics, the effects of HFJV and IPPV on CBF are comparable at identical levels of mean airway pressure.

Pittet, J.F.; Forster, A.; Suter, P.M. (University Hospital of Geneva (Switzerland))

1990-02-01

261

Intestinal perfusion monitoring using photoplethysmography  

NASA Astrophysics Data System (ADS)

In abdominal trauma patients, monitoring intestinal perfusion and oxygen consumption is essential during the resuscitation period. Photoplethysmography is an optical technique potentially capable of monitoring these changes in real time to provide the medical staff with a timely and quantitative measure of the adequacy of resuscitation. The challenges for using optical techniques in monitoring hemodynamics in intestinal tissue are discussed, and the solutions to these challenges are presented using a combination of Monte Carlo modeling and theoretical analysis of light propagation in tissue. In particular, it is shown that by using visible wavelengths (i.e., 470 and 525 nm), the perfusion signal is enhanced and the background contribution is decreased compared with using traditional near-infrared wavelengths leading to an order of magnitude enhancement in the signal-to-background ratio. It was further shown that, using the visible wavelengths, similar sensitivity to oxygenation changes could be obtained (over 50% compared with that of near-infrared wavelengths). This is mainly due to the increased contrast between tissue and blood in that spectral region and the confinement of the photons to the thickness of the small intestine. Moreover, the modeling results show that the source to detector separation should be limited to roughly 6 mm while using traditional near-infrared light, with a few centimeters source to detector separation leads to poor signal-to-background ratio. Finally, a visible wavelength system is tested in an in vivo porcine study, and the possibility of monitoring intestinal perfusion changes is showed.

Akl, Tony J.; Wilson, Mark A.; Ericson, M. Nance; Coté, Gerard L.

2013-08-01

262

Shoulder strength imbalances as injury risk in handball.  

PubMed

This study was conducted to analyze whether internal (IR) and external (ER) rotator shoulder muscles weakness and/or imbalance collected through a preseason assessment could be predictors of subsequent shoulder injury during a season in handball players. In preseason, 16 female elite handball players (HPG) and 14 healthy female nonathletes (CG) underwent isokinetic IR and ER strength test with use of a Con-Trex® dynamometer in a seated position with 45° shoulder abduction in scapular plane, at 60, 120 and 240°/s in concentric and at 60°/s in eccentric, for both sides. An imbalanced muscular strength profile was determined using -statistically selected cut-offs from CG values. For HPG, all newly incurred shoulder injuries were reported during the season. There were significant differences between HPG and CG only for dominant eccentric IR strength, ER/IR ratio at 240°/s and for IRecc/ERcon ratio. In HPG, IR and ER strength was higher, and ER/IR ratios lower for dominant than for nondominant side. The relative risk was 2.57 (95%CI: 1.60-3.54; P<0.05) if handball players had an imbalanced muscular strength profile. In youth female handball players IR and ER muscle strength increases on the dominant side without ER/IR imbalances; and higher injury risk was associated with imbalanced muscular strength profile. PMID:23444085

Edouard, P; Degache, F; Oullion, R; Plessis, J-Y; Gleizes-Cervera, S; Calmels, P

2013-02-26

263

Effects of imbalance and geometric error on precision grinding machines  

SciTech Connect

To study balancing in grinding, a simple mechanical system was examined. It was essential to study such a well-defined system, as opposed to a large, complex system such as a machining center. The use of a compact, well-defined system enabled easy quantification of the imbalance force input, its phase angle to any geometric decentering, and good understanding of the machine mode shapes. It is important to understand a simple system such as the one I examined given that imbalance is so intimately coupled to machine dynamics. It is possible to extend the results presented here to industrial machines, although that is not part of this work. In addition to the empirical testing, a simple mechanical system to look at how mode shapes, balance, and geometric error interplay to yield spindle error motion was modelled. The results of this model will be presented along with the results from a more global grinding model. The global model, presented at ASPE in November 1996, allows one to examine the effects of changing global machine parameters like stiffness and damping. This geometrically abstract, one-dimensional model will be presented to demonstrate the usefulness of an abstract approach for first-order understanding but it will not be the main focus of this thesis. 19 refs., 36 figs., 10 tables.

Bibler, J.E.

1997-06-01

264

The effect of spinal manipulation on imbalances in leg strength  

PubMed Central

We hypothesized that spinal manipulation (SM) would reduce strength imbalances between legs. Using an un-blinded randomized design, 28 males and 21 females (54 ± 19y) with at least a 15% difference in isometric strength between legs for hip flexion, extension, abduction, or knee flexion were randomized to treatment or placebo (mock spinal manipulation). Strength of the stronger and weaker legs for hip flexion, extension, abduction, and/or knee flexion was assessed before and after the intervention. SM reduced the relative strength difference between legs for knee flexion (mean ± SD 57 ± 53 to 5 ± 14%) and hip flexion (24 ± 12 to 11 ± 15%) compared to placebo (34 ± 29 to 24 ± 36%, and 20 ± 18 to 22 ± 26%, respectively) (p = 0.05). SM also improved strength in the weak leg for hip abduction (104 ± 43 to 116 ± 43 Nm) compared to placebo (84 ± 24 to 85 ± 31 Nm) (p = 0.03). This study suggests that spinal manipulation may reduce imbalances in strength between legs for knee and hip flexion.

Chilibeck, Philip D.; Cornish, Stephen M.; Schulte, Al; Jantz, Nathan; Magnus, Charlene R.A.; Schwanbeck, Shane; Juurlink, Bernhard H.J.

2011-01-01

265

Earth's Radiation Imbalance from a Constellation of 66 Iridium Satellites  

NASA Astrophysics Data System (ADS)

The Earth Radiation Imbalance (ERI) at the top of the atmosphere is the primary driving force for climate change. If ERI is not zero, then Earth's temperature, both oceanic and atmospheric, will change gradually over time, tending toward a new steady state. The best estimates of current ERI from climate models range from 0.4 to 0.9 W/m2 (the imbalance being caused mainly by increasing CO2), but current satellite systems do not have the accuracy to measure ERI to even one significant digit. In this paper, we will describe a proposed constellation of 66 Earth radiation budget instruments, to be hosted on Iridium satellites. This system represents a quantum leap over current systems in several ways, in particular in providing ERI to at least one significant digit, thus enabling a crucial test of climate models. Because of its 24/7 coverage, the system will also provide ERI at three-hourly time scales without requiring extrapolations from narrowband geostationary instruments. This would allow studies of ERI's response to fast-evolving phenomena like dust storms and hurricanes. This offers a new, synoptic view of Earth radiation budget that will transform it from a monthly average into a dynamical variable alongside standard meteorological variables like temperature and pressure.

Chiu, J. C.; Wiscombe, W. J.

2012-04-01

266

Residential ventilation standards scoping study  

SciTech Connect

The goals of this scoping study are to identify research needed to develop improved ventilation standards for California's Title 24 Building Energy Efficiency Standards. The 2008 Title 24 Standards are the primary target for the outcome of this research, but this scoping study is not limited to that timeframe. We prepared this scoping study to provide the California Energy Commission with broad and flexible options for developing a research plan to advance the standards. This document presents the findings of a scoping study commissioned by the Public Interest Energy Research (PIER) program of the California Energy Commission to determine what research is necessary to develop new residential ventilation requirements for California. This study is one of three companion efforts needed to complete the job of determining the ventilation needs of California residences, determining the bases for setting residential ventilation requirements, and determining appropriate ventilation technologies to meet these needs and requirements in an energy efficient manner. Rather than providing research results, this scoping study identifies important research questions along with the level of effort necessary to address these questions and the costs, risks, and benefits of pursuing alternative research questions. In approaching these questions and corresponding levels of effort, feasibility and timing were important considerations. The Commission has specified Summer 2005 as the latest date for completing this research in time to update the 2008 version of California's Energy Code (Title 24).

McKone, Thomas E.; Sherman, Max H.

2003-10-01

267

An adaptive lung ventilation controller.  

PubMed

Closed loop control of ventilation is traditionally based on end-tidal or mean expired CO2. The controlled variables are the respiratory rate RR and the tidal volume VT. Neither patient size or lung mechanics were considered in previous approaches. Also the modes were not suitable for spontaneously breathing subjects. This report presents a new approach to closed loop controlled ventilation, called Adaptive Lung Ventilation (ALV). ALV is based on a pressure controlled ventilation mode suitable for paralyzed, as well as spontaneously breathing, subjects. The clinician enters a desired gross alveolar ventilation (V'gA in l/min), and the ALV controller tries to achieve this goal by automatic adjustment of mechanical rate and inspiratory pressure level. The adjustments are based on measurements of the patient's lung mechanics and series dead space. The ALV controller was tested on a physical lung model with adjustable mechanical properties. Three different lung pathologies were simulated on the lung model to test the controller for rise time (T90), overshoot (Ym), and steady state performance (delta max). The pathologies corresponded to restrictive lung disease (similar to ARDS), a "normal" lung, and obstructive lung disease (such as asthma). Furthermore, feasibility tests were done in 6 patients undergoing surgical procedures in total intravenous anesthesia. In the model studies, the controller responded to step changes between 48 seconds and 81 seconds. It did exhibit an overshoot between 5.5% and 7.9% of the setpoint after the step change.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8200668

Laubscher, T P; Heinrichs, W; Weiler, N; Hartmann, G; Brunner, J X

1994-01-01

268

Phosphoinositide 3-OH kinase inhibition prevents ventilation-induced lung cell activation.  

PubMed

In acute respiratory distress syndrome patients, protective ventilation strategies reduce mortality and proinflammatory mediator levels. It has been suggested that some of the side effects of mechanical ventilation are caused by the excessive release of mediators capable of causing pulmonary inflammation and tissue destruction (biotrauma). Selective inhibition of this process might be used to minimize the side effects of artificial mechanical ventilation. This study was designed to identify the cell types and specific signaling mechanisms that are activated by ventilation with increased pressure/volume (overventilation). In isolated perfused mouse lungs, overventilation caused nuclear translocation of nuclear factor-kappaB (NF-kappaB) and enhanced expression of interleukin-6 mRNA in alveolar macrophages and alveolar epithelial type II cells. The phosphoinositide 3-OH kinase inhibitor Ly294002 prevented nuclear translocation of NF-kappaB and the subsequent release of interleukin-6 and macrophage inflammatory protein-2alpha in overventilated but not in endotoxic lungs. Similar results were obtained in rats in vivo, where Ly294002 prevented NF-kappaB activation by overventilation but not by endotoxin. These findings show that alveolar macrophages and alveolar epithelial type II cells contribute to the ventilation-induced release of proinflammatory mediators and that selective inhibition of this process is possible without inhibiting the activation of NF-kappaB by endotoxin. PMID:14578214

Uhlig, Ulrike; Fehrenbach, Heinz; Lachmann, Robert A; Goldmann, Torsten; Lachmann, Burkhard; Vollmer, Ekkehard; Uhlig, Stefan

2003-10-24

269

Compensation schemes and performance analysis of IQ imbalances in OFDM receivers  

Microsoft Academic Search

The implementation of orthogonal frequency division multiplexing (OFDM)-based physical layers suffers from the effect of In-phase and Quadrature-phase (IQ) imbalances in the front-end analog processing. The IQ imbalances can severely limit the achievable operating signal-to-noise ratio (SNR) at the receiver and, consequently, the supported constellation sizes and data rates. In this paper, the effect of IQ imbalances on OFDM receivers

Alireza Tarighat; Rahim Bagheri; Ali H. Sayed

2005-01-01

270

A real-time DSP-based imbalance analysis system for rotating machine with vibration signal  

Microsoft Academic Search

This paper describes a new digital signal processor (DSP) imbalance measurement system dedicated to real-time vibration analysis\\u000a on rotating machine. To accomplish real-time analysis, the vibration signals are on-line acquired and processed to analyze\\u000a the mass imbalance and phase position. This is achieved through the use of FFT and Lissajous diagram. The method followed\\u000a to analyze the mass imbalance with

Hua Su; Linglong Huang; Kil To Chong

2005-01-01

271

The measurement of effort–reward imbalance at work: European comparisons  

Microsoft Academic Search

Using comparative data from five countries, this study investigates the psychometric properties of the effort–reward imbalance (ERI) at work model. In this model, chronic work-related stress is identified as non-reciprocity or imbalance between high efforts spent and low rewards received. Health-adverse effects of this imbalance were documented in several prospective and cross-sectional investigations. The internal consistency, discriminant validity and factorial

Johannes Siegrist; Dagmar Starke; Tarani Chandola; Isabelle Godin; Michael Marmot; Isabelle Niedhammer; Richard Peter

2004-01-01

272

Quality assessment of a placental perfusion protocol.  

PubMed

Validation of in vitro test systems using the modular approach with steps addressing reliability and relevance is an important aim when developing in vitro tests in e.g. reproductive toxicology. The ex vivo human placental perfusion system may be used for such validation, here presenting the placental perfusion model in Copenhagen including control substances. The positive control substance antipyrine shows no difference in transport regardless of perfusion media used or of terms of delivery (n=59, p<0.05). Negative control studies with FITC marked dextran correspond with leakage criteria (<3 ml h(-1) from the fetal reservoir) when adding 2 (n=7) and 20mg (n=9) FITC-dextran/100 ml fetal perfusion media. Success rate of the Copenhagen placental perfusions is provided in this study, including considerations and quality control parameters. Three checkpoints suggested to determine success rate revealed that 15% of the cannulated placentae received in one year (n=202) were successfully perfused. PMID:20096346

Mathiesen, Line; Mose, Tina; Mørck, Thit Juul; Nielsen, Jeanette Kolstrup Søgaard; Nielsen, Leif Kofoed; Maroun, Lisa Leth; Dziegiel, Morten Hanefeld; Larsen, Lise Grupe; Knudsen, Lisbeth Ehlert

2010-01-21

273

Tc-99m-DTPA aerosol and radioactive gases compared as adjuncts to perfusion scintigraphy in patients with suspected pulmonary embolism  

SciTech Connect

To evaluate the clinical utility of improved methods for radioaerosol inhalation imaging, we obtained preperfusion radioaerosol images in 107 patients (mean age = 62 years), who were referred for evaluation of suspected pulmonary embolism (PE). For each patient, we compared six-view aerosol images with accompanying perfusion scans and chest radiographs and with Xenon-133 (Xe-133) or Krypton-81 m (Kr-81m) studies. Four observers at four different institutions independently evaluated aerosol-perfusion and gas-perfusion pairs, classifying the probability of PE as low, high, or indeterminate. The results suggest that radioaerosol inhalation studies, performed with improved nebulizers, are diagnostically equivalent to ventilation imaging as an adjunct to perfusion scintigraphy in evaluating patients with suspected PE.

Alderson, P.O.; Biello, D.R.; Gottschalk, A.; Hoffer, P.B.; Kroop, S.A.; Lee, M.E.; Ramanna, L.; Siegel, B.A.; Waxman, A.D.

1984-11-01

274

Obtained Diversity Gain in OFDM Systems under the Influence of IQ Imbalance  

NASA Astrophysics Data System (ADS)

In this paper, we analyze the effects of IQ (In-phase/Quadrature-phase) imbalance at both transmitter and receiver of OFDM (Orthogonal Frequency Division Multiplexing) system and show that more diversity gain can be achieved even though there are unwanted IQ imbalance. When mixed sub-carriers within an OFDM symbol due to the IQ imbalance undergo frequency selective channels, additional diversity effects are expected during the demodulation process. Simulation results on the symbol error rate (SER) performance with ML (Maximum Likelihood) and OSIC (Ordered Successive Interference Cancellation) receiver show that significant performance gain can be achieved with the diversity gain caused by the IQ imbalance combined with the frequency selective channels.

Jin, Younghwan; Kwon, Jihyeon; Lee, Yuro; Lee, Dongchan; Ahn, Jaemin

275

Myocardial performance and perfusion during exercise in patients with coronary artery disease caused by Kawasaki disease  

SciTech Connect

For a study of the natural history of coronary artery lesions after Kawasaki disease and their effect on myocardial blood flow reserve with exercise, five such patients underwent exercise testing on a bicycle. Oxygen consumption, carbon dioxide production, minute ventilation, and electrocardiograms were monitored continuously. Thallium-201 scintigraphy was performed for all patients. One patient stopped exercise before exhaustion of cardiovascular reserve but had no evidence of myocardial perfusion abnormalities. Four patients terminated exercise because of exhaustion of cardiovascular reserve; one had normal cardiovascular reserve and thallium scintiscans, but the remaining patients had diminished cardiovascular reserve. Thallium scintigrams showed myocardial ischemia in two and infarction in one. No patient had exercise-induced electrocardiographic changes. These results indicate that patients with residual coronary artery lesions after Kawasaki disease frequently have reduced cardiovascular reserve during exercise. The addition of thallium scintigraphy and metabolic measurements to exercise testing improved the detection of exercise-induced abnormalities of myocardial perfusion.

Paridon, S.M.; Ross, R.D.; Kuhns, L.R.; Pinsky, W.W. (Wayne State Univ. School of Medicine, Detroit (USA))

1990-01-01

276

Movement artefact suppression in blood perfusion measurements using a multifrequency technique.  

PubMed

The standard way of suppressing movement artefacts in Doppler measurements is by means of a high-pass filter. This is because artefacts usually are of high amplitude, but have low frequencies. The immediate drawback is, then, that low-velocity blood flow is also filtered out. In this paper, a method to reduce movement artefacts in blood perfusion measurements is proposed, using simultaneous transmission and reception of multiple frequencies in a continuous-wave Doppler system. It is shown that Doppler signals originating from blood may be considered uncorrelated for a large enough frequency separation between channels, and tissue movements are more correlated. By subtracting perfusion estimates obtained by time-domain processing, correlated signals can be suppressed. The subtraction algorithm is shown to produce a linear perfusion estimate, but with twice the standard deviation compared to an estimate obtained by simply averaging channels. Movement artefacts in both in vitro and in vivo models are shown to be reduced by the algorithm. Imbalance between channels does, however, cause the artefacts to be only partly reduced. The problem can be alleviated by filtering the signals prior to subtraction, but this results in a nonlinear estimate, especially for large time constants in the filter. Some amount of filtering can still be desirable to suppress partly correlated artefacts, even if identical time-domain processing units are implemented, as could be done digitally. PMID:11879954

Jansson, Tomas; Persson, Hans W; Lindström, Kjell

2002-01-01

277

Magnetic resonance perfusion imaging without contrast media  

Microsoft Academic Search

Purpose  Principles of magnetic resonance imaging techniques providing perfusion-related contrast weighting without administration\\u000a of contrast media are reported and analysed systematically. Especially common approaches to arterial spin labelling (ASL) perfusion imaging allowing quantitative assessment of specific perfusion rates are described in detail. The potential\\u000a of ASL for perfusion imaging was tested in several types of tissue.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  After a systematic comparison of

Petros Martirosian; Andreas Boss; Christina Schraml; Nina F. Schwenzer; Hansjörg Graf; Claus D. Claussen; Fritz Schick

2010-01-01

278

Patterns of pulmonary perfusion scans in normal subjects. IV. The prevalence of abnormal scans in smokers 30 to 49 years of age  

SciTech Connect

The usefulness of ventilation-perfusion scans in the diagnosis of pulmonary embolism is limited by the wide range of pulmonary diseases that are associated with abnormal scans, and by the largely undetermined prevalence of abnormal scans in persons without cardiopulmonary disease. In prior studies, we found perfusion defects to be rarely present in young persons and in older nonsmokers. To determine if normal older smokers have a higher prevalence of abnormal ventilation and perfusion scans, we performed six-view /sup 99m/Tc perfusion (Q) scans and /sup 133/Xe ventilation (V) scans in 40 subjects 30 to 49 yr of age who had no known cardiopulmonary disease. Each subject had undergone a history, physical examination, electrocardiogram, spirometry, and posteroanterior chest roentgenogram prior to scanning. All V and Q scans were interpreted blindly and independently by two experienced readers. No subject demonstrated a lobar or segmental defect on two views. One subject had a matched subsegmental defect, and one subject had delayed washout from a subsegmental area of the right upper lobe during V scanning, with a normal Q scan. We conclude that abnormal V and Q scans are uncommon among normal smokers 30 to 49 yr of age.

Fedullo, P.F.; Kapitan, K.S.; Brewer, N.S.; Ashburn, W.L.; Hartman, M.T.; Moser, K.M.

1989-05-01

279

Lung-lung interaction in isolated perfused unilateral hyperventilated rat lungs.  

PubMed

The technique of conducting high tidal volume (TV) ventilation-induced lung inflammation including remote organs is still open to discussion, and our aim is to investigate this issue in isolated ventilated rat lungs perfused with salt solution. Selective right lung (RL) hyperventilation (TV of 15 mL/kg with air containing 5% CO(2) on zero or 2.5 cm H(2)0 end expiratory pressure [ZEEP or PEEP] in addition to left lung (LL) on 2.5 cm H(2)0 continuous positive airway pressure (CPAP) for 60 min, was realized after 30 min both lungs ventilation by occluding the left main bronchus, and it was allocated to the following 5 groups: groups 1 and 2 underwent hyperventilation under ZEEP, groups 3 and 4 underwent hyper ventilation under PEEP with recirculation or nonrecirculation (R-ZEEP or NR-ZEEP and R-PEEP or NR-PEEP), and group 5 served as the control group. Recirculation means the same perfusate recirculates the system throughout the procedure. The wet/dry ratio and protein content of bronchoalveolar lavage fluid (Prot-BALF), cytokine messenger RNAs (mRNAs), localization of tumor necrosis factor-alpha (TNF-alpha) by immunofluorescence double staining, and TNF-alpha concentration in the perfusate and BALF in each lung were measured and compared between groups by Kruskal-Wallis test. Lung injury (increased wet/dry ratio, Prot-BALF, and TNF-alpha on endothelial and epithelial cells) was shown in the hyperventilated RLs with ZEEP compared with their corresponding CPAP LLs. PEEP prevented these injuries. Lung injury was also demonstrated in the recirculated LL compared with the nonrecirculated LL (Prot-BALF, TNF-alpha and interleukin-1beta [IL-1beta] mRNAs: the LL of the R-ZEEP is greater than the LL of NR-ZEEP by P < 0.01). Unilateral hyperventilated lungs with ZEEP induced TNF-alpha, increased permeability, and injured the control lung via perfusion. PMID:20403578

Bilali, Aishan; Kurata, Shunichi; Ikeda, Satoshi; Georgieva, Gabriela S; Zhu, Chenting; Tomita, Makoto; Katoh, Iyoko; Mitaka, Chieko; Eishi, Yoshinobu; Imai, Takasuke

2010-02-10

280

46 CFR 108.181 - Ventilation for enclosed spaces.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Ventilation for enclosed spaces. 108.181 Section 108.181 Shipping ...Ventilation § 108.181 Ventilation for enclosed spaces. (a) Each enclosed space must be vented or ventilated. (b)...

2012-10-01

281

Efficacy of Intermittent Ventilation for Providing Acceptable Indoor Air Quality.  

National Technical Information Service (NTIS)

Ventilation standards and guidelines typically treat ventilation as a constant and specify its value. In many circumstances a designer wishes to use intermittent ventilation, rather than constant ventilation, but there are no easy equivalencies available....

M. H. Sherman

2004-01-01

282

Commissioning Ventilated Containment Systems in the Laboratory.  

National Technical Information Service (NTIS)

This Best Practices Guide focuses on the specialized approaches required for ventilated containment systems, understood to be all components that drive and control ventilated enclosures and local exhaust systems within the laboratory. Geared toward archit...

2008-01-01

283

14 CFR 252.9 - Ventilation systems.  

Code of Federal Regulations, 2013 CFR

...DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.9 Ventilation systems. Air carriers shall prohibit smoking whenever the ventilation system is not fully functioning. Fully...

2013-01-01

284

21 CFR 868.5975 - Ventilator tubing.  

Code of Federal Regulations, 2013 CFR

...Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5975 Ventilator tubing. (a) Identification. Ventilator tubing is...

2013-04-01

285

JAMA Patient Page: Ventilator-Associated Pneumonia  

MedlinePLUS

... rare cases, open lung biopsy to obtain lung tissue may be done. • Antibiotics remain the cornerstone of therapy for ventilator-associated pnuemonia. Choice of antibiotic is guided by bacteria culture results. • Because ventilator-associated pnuemonia occurs in hospitalized ...

286

Comparative Tests on Calves. Insulation - Ventilation - Heating.  

National Technical Information Service (NTIS)

Comparative tests have been carried out in 3 calf houses, of which one was insulated, mechanically ventilated and heated (KA-1), another was insulated and had an automatically regulated natural ventilation system without heating (KA-2), and the third hous...

K. Hansen

1984-01-01

287

A case of myotonic dystrophy with electrolyte imbalance.  

PubMed

Type 1 myotonic dystrophy (DM1) is an autosomal-dominant inherited disorder with a multisystem involvement, caused by an abnormal expansion of the CTG sequence of the dystrophic myotonia protein kinase (DMPK) gene. DM1 is a variable multisystem disorder with muscular and nonmuscular abnormalities. Increasingly, endocrine abnormalities, such as gonadal, pancreatic, and adrenal dysfunction are being reported. But, Electrolytes imbalance is a very rare condition in patients with DM1 yet. Herein we present a 42-yr-old Korean male of DM1 with abnormally elevated serum sodium and potassium. The patient had minimum volume of maximally concentrated urine without water loss. It was only cured by normal saline hydration. The cause of hypernatremia was considered by primary hypodipsia. Hyperkalemic conditions such as renal failure, pseudohyperkalemia, cortisol deficiency and hyperkalemic periodic paralysis were excluded. Further endocrine evaluation suggested selective hyperreninemic hypoaldosteronism as a cause of hyperkalemia. PMID:23853500

Ko, Weon-Jin; Kim, Kwang-Yeol; Kim, So-Mi; Hong, Seung-Jae; Lee, Sang-Hoon; Song, Ran; Yang, Hyung-In; Lee, Yeon-Ah

2013-07-03

288

Colombian late cretaceous tropical planktonic foraminifera: Redressing the imbalance  

SciTech Connect

Recent work involving Late Cretaceous planktonic foraminifera has concentrated on European and other areas in the Northern Hemisphere. Many of the biostratigraphical and evolutionary models reflect this geographical restriction and ignore earlier studies from tropical areas. In 1955 Rolando Gandolfi described many new species and subspecies from Colombia and provided a different view of the evolutionary development of planktonic foraminifera. A re-examination of the Gandolfi type collection using Scanning Electron Micrography (Environmental Chamber technique) integrated with Colombian well samples from onshore Guajira area, Middle and Upper Magdalena Valley and Putumayo Basin has given a new view into the evolutionary development of Late Cretaceous planktonic foraminifera. This has enabled a modified globigerine Late Cretaceous biostratigraphy to be constructed for Colombia. This work redresses the imbalance between studies of tropical and northern high latitude Late Cretaceous planktonic foraminifera and provides an insight into the paleoenvironmental and paleoclimatological factors influencing the Colombian region at the time.

McCarthy, L.D.

1993-02-01

289

"Molecular rulers" for calibrating phenotypic effects of telomere imbalance  

PubMed Central

As a result of the increasing use of genome wide telomere screening, it has become evident that a significant proportion of people with idiopathic mental retardation have subtle abnormalities involving the telomeres of human chromosomes. However, during the course of these studies, there have also been telomeric imbalances identified in normal people that are not associated with any apparent phenotype. We have begun to scrutinise cases from both of these groups by determining the extent of the duplication or deletion associated with the imbalance. Five cases were examined where the telomere rearrangement resulted in trisomy for the 16p telomere. The size of the trisomic segment ranged from ?4-7 Mb and the phenotype included mental and growth retardation, brain malformations, heart defects, cleft palate, pancreatic insufficiency, genitourinary abnormalities, and dysmorphic features. Three cases with telomeric deletions without apparent phenotypic effects were also examined, one from 10q and two from 17p. All three deletions were inherited from a phenotypically normal parent carrying the same deletion, thus without apparent phenotypic effect. The largest deletion among these cases was ?600 kb on 17p. Similar studies are necessary for all telomeric regions to differentiate between those telomeric rearrangements that are pathogenic and those that are benign variants. Towards this goal, we are developing "molecular rulers" that incorporate multiple clones at each telomere that span the most distal 5 Mb region. While telomere screening has enabled the identification of telomere rearrangements, the use of molecular rulers will allow better phenotype prediction and prognosis related to these findings.

Martin, C; Waggoner, D; Wong, A; Uhrig, S; Roseberry, J; Hedrick, J; Pack, S; Russell, K; Zackai, E; Dobyns, W; Ledbetter, D

2002-01-01

290

Equipment needs for noninvasive mechanical ventilation  

Microsoft Academic Search

ABSTRACT: Noninvasive mechanical,ventilation (NIV) has a long tradition for the treatment of chronic respiratory failure and more recently has also been applied in acute respiratory failure. Based on this experience both critical care ventilators and portable ventilators are used to perform,NIV. The individual choice of ventilator type should depend on the patient9s condition and also on the expertise of attending

B. Schonhofer; S. Sortor-Leger

2002-01-01

291

Ventilator-Associated Pneumonia: A Review  

Microsoft Academic Search

Ventilator-associated pneumonia is the most frequent intensive care unit (ICU)-related infection in patients requiring mechanical ventilation. In contrast to other ICU-related infections, which have a low mortality rate, the mortality rate for ventilator-associated pneumonia ranges from 20% to 50%. These clinically significant infections prolong duration of mechanical ventilation and ICU length of stay, underscoring the financial burden these infections impose

Kimberly A. Davis

2006-01-01

292

[Mechanical ventilation in pediatrics (III). Weaning, complications and other types of ventilation. Compications of mechanical ventilation].  

PubMed

Mechanical ventilation can produce multiple complications. The most important acute complications are mechanical problems (respirator failure, problems with the connections and circuit, incorrect parameters or alarms), problems in the airway (disconnection, extubation, mal-positioning of the endotracheal tube, leaks, nose erosions, obstruction of the endotracheal tube due to secretions or kinking, mainstem bronchus intubation, bronchospasm, postextubation croup), pulmonary complications (ventilator-induced lung injury with barotrauma, volutrauma and biotrauma), hemodynamic complications, nosocomial infections (tracheobronchitis, pneumonia, otitis, sinusitis), failure of adjustment of the respirator to the patient, and nutritional complications. The most important chronic problems are subglottal stenosis, chronic pulmonary injury, and psychological alterations. PMID:14562840

Reina Ferragut, C; López-Herce, J

2003-08-01

293

Noninvasive Positive Pressure Ventilation in burns  

Microsoft Academic Search

Objective: Acute respiratory failure is a common complication of the severely burn-injured patient. Endotracheal intubation and mechanical ventilation is associated with a high rate of complications. Noninvasive Positive Pressure Ventilation (NIPPV) has been shown to be as effective as conventional ventilation in improving gas exchange and is associated with fewer complications with patients in acute hypercapnic and hypoxaemic respiratory failure.

S. T Smailes

2002-01-01

294

Myocardial perfusion modeling using MRI.  

PubMed

In the present study, it is shown that it is possible to quantify myocardial perfusion using magnetic resonance imaging in combination with gadolinium diethylenetriaminopentaacetic acid (Gd-DTPA). Previously, a simple model and method for measuring myocardial perfusion using an inversion recovery turbo-FLASH (fast low-angle shot) sequence and Gd-DTPA has been presented. Here, an extension of the model is presented taking into account fast and slow water exchange between the compartments, enabling the calculation of the unidirectional influx constant (Ki) for Gd-DTPA, the distribution volume of Gd-DTPA (lambda), the vascular blood volume (Vb), and the time delay through the coronary arteries (delta T). The model was evaluated by computer simulation and used on experimental results from seven healthy subjects. The results in the healthy volunteers for a region of interest placed in the anterior myocardial wall were (mean +/- SD) Ki = 54 +/- 10 ml/100 g/min, lambda = 30 +/- 3 ml/100 g, Vb = 9 +/- 2 ml/100 g, delta T = 3.2 +/- 1.1 s. These results are in good agreement with similar results obtained by other methods. PMID:8722823

Larsson, H B; Fritz-Hansen, T; Rostrup, E; Søndergaard, L; Ring, P; Henriksen, O

1996-05-01

295

Cardiovascular Effects of Mechanical Ventilation  

Microsoft Academic Search

Objective: To review the cardiovascular effects of spontaneous breathing and mechanical ventilation in healthy and pathological states. Data sources: A review of articles published in peer-reviewed journals from 1966 to 1998 and identified through a MEDLINE search on cardiopulmonary interaction. Summary of review: Respiration has a hydraulic influence upon cardiovascular function. Pulmonary and cardiac pathology alter this interaction. Spontaneous inspiration

G. J. DUKE

1999-01-01

296

Fire Service Training. Ventilation. (Revised).  

ERIC Educational Resources Information Center

|One of a set of fourteen outlines for use in a course to train novice firemen, this guide covers ventilation practices and principles. As background, subjects such as heat transmission and building construction are included. The three objectives of this part of the course are to enable the fireman to (1) rescue trapped victims, (2) locate fires…

North Carolina State Dept. of Community Colleges, Raleigh.

297

Monitoring for ventilation and airtightness  

SciTech Connect

The object of this paper is to show how the monitoring of key IAQ parameters can provide feedback on building performance in the areas of ventilation and airtightness. The availability of this information can then lead to the more effective operation of the building and its HVAC system because the operators will have better information on system operation. The monitoring of carbon dioxide (CO{sub 2}) concentrations, for instance, provides feedback on many aspects of HVAC performance includes information on the adequacy of ventilation, the uniformity of ventilation, and the effectiveness of the overnight purge. Coupled with the monitoring of humidity, feedback on airtightness and energy efficiency also becomes available. The monitoring of multiple parameters of the indoor environment at strategically selected multiple locations in buildings, therefore, can provide important information on HVAC performance. As such, it can improve the management of buildings by reducing the amount of uncertainty in this performance. The better the operators know what the HVAC system is doing, the better they can optimize its performance for both ventilation adequacy and minimum energy use.

Bearg, D.W.

2000-07-01

298

Novel modes of mechanical ventilation.  

PubMed

The overarching goal of positive pressure mechanical ventilation is to provide adequate gas exchange support while not causing harm. Indeed, positive pressure mechanical ventilators are only support technologies, not therapeutic technologies. As such they cannot be expected to "cure" disease; they can only "buy time" for other therapies (including the patient's own defenses) to work.Conventional approaches to positive pressure ventilation involve applying ventilatory patterns mimicking normal ones through either masks or artificial airways. This is usually done with modes of support incorporating assist/control breath-triggering mechanisms, gas delivery patterns governed by either a set flow or pressure, and breath cycling based on either a set volume, a set inspiratory time, or a set flow. Often this support includes positive end-expiratory pressure and supplemental oxygen. In recent decades several novel or unconventional approaches to providing mechanical ventilatory support have been introduced. For these to be considered of value, however, it would seem reasonable that they address important clinical challenges and be shown to improve important clinical outcomes (e.g., mortality, duration of ventilation, sedation needs, complications). This article focuses on challenges facing clinicians in providing mechanical ventilatory support and assesses several novel approaches introduced over the last 2 decades in the context of these challenges. PMID:23934718

Al-Hegelan, Mashael; MacIntyre, Neil R

2013-08-11

299

Review of Residential Ventilation Technologies  

SciTech Connect

This paper reviews current and potential ventilation technologies for residential buildings in North America and a few in Europe. The major technologies reviewed include a variety of mechanical systems, natural ventilation, and passive ventilation. Key parameters that are related to each system include operating costs, installation costs, ventilation rates, heat recovery potential. It also examines related issues such as infiltration, duct systems, filtration options, noise, and construction issues. This report describes a wide variety of systems currently on the market that can be used to meet ASHRAE standard 62.2. While these systems generally fall into the categories of supply, exhaust or balanced, the specifics of each system are driven by concerns that extend beyond those in the standard and are discussed. Some of these systems go beyond the current standard by providing additional features (such as air distribution or pressurization control). The market will decide the immediate value of such features, but ASHRAE may wish to consider modifications to the standard in the future.

Russell, Marion L.; Sherman, Max H.; Rudd, Armin

2005-03-01

300

Artificial ventilation in severe pertussis  

Microsoft Academic Search

A retrospective review was conducted of all children admitted to our intensive care unit over eight years with a diagnosis of pertussis that had been proved on culture. Altogether 789 children were seen as outpatients and inpatients. Twenty four of these children were admitted to the intensive care unit, 13 of whom required ventilatory support; two of the ventilated patients

J Gillis; T Grattan-Smith; H Kilham

1988-01-01

301

Wife Beating in South Africa: An Imbalance Theory of Resources and Power  

ERIC Educational Resources Information Center

|This article develops an imbalance theory to explain physical violence against women in intimate relationships in South Africa. The theory proposes four typologies: dependence, compensation, submission, and transgression, through which imbalances in resource contribution and power distribution between spouses are hypothesized to contribute to…

Choi, Susanne Y. P.; Ting, Kwok-Fai

2008-01-01

302

Perception of unsteadiness in patients with dizziness: Association with handicap and imbalance  

Microsoft Academic Search

Dizziness is a common problem in patients seeking medical help and is often associated with imbalance and handicap. This study aimed to reveal whether the perception of unsteadiness could be an indication of greater imbalance and handicap in these patients. Patients with dizziness were categorized into two groups, steady patients (n=15) and unsteady patients (n=23), based on the presence or

Sang-I Lin; Tzu-Tung Tsai; I-Hsin Lee; Ye-Ning Wu

2002-01-01

303

A novel IQ imbalance compensation scheme for the reception of OFDM signals  

Microsoft Academic Search

Digital receivers still employ analog components in the demodulation process causing amplitude and phase imbalances between the I and Q branches. This article describes a novel digital compensation scheme for orthogonal frequency division multiplex (OFDM) receivers based on adaptive frequency domain filtering to remove the IQ imbalance effects

Andreas Schuchert; Ralph Hasholzner; Patrick Antoine

2001-01-01

304

A comparison between the effort-reward imbalance and demand control models  

PubMed Central

Background To compare the predictive validity of the demand/control and reward/imbalance models, alone and in combination with each other, for self-reported health status and the self-reported presence of any chronic disease condition. Methods Self-reports for psychosocial work conditions were obtained in a sample of sawmill workers using the demand/control and effort/reward imbalance models. The relative predictive validity of task-level control was compared with effort/reward imbalance. As well, the predictive validity of a model developed by combining task-level control with effort/reward imbalance was determined. Logistic regression was utilized for all models. Results The demand/control and effort/reward imbalance models independently predicted poor self-reported health status. The effort-reward imbalance model predicted the presence of a chronic disease while the demand/control model did not. A model combining effort-reward imbalance and task-level control was a better predictor of self-reported health status and any chronic condition than either model alone. Effort reward imbalance modeled with intrinsic effort had marginally better predictive validity than when modeled with extrinsic effort only. Conclusions Future work should explore the combined effects of these two models of psychosocial stress at work on health more thoroughly.

Ostry, Aleck S; Kelly, Shona; Demers, Paul A; Mustard, Cameron; Hertzman, Clyde

2003-01-01

305

Linking External Sector Imbalances and Changing Financial Instability before the 2008 Financial Crisis  

Microsoft Academic Search

The G20 Framework for Strong, Sustainable and Balanced Growth builds on the claim that growing imbalances before the 2008 Financial Crisis were a major cause of the crisis, and the further claim that reducing imbalances post crisis must be a central part of any effort to prevent a further occurrence. Analytical literature in economics seemingly does not provide satisfactory measures

John Whalley; Manmohan Agarwal; Jing Wang; Sean Walsh; Chen Yan

2011-01-01

306

To ventilate, oscillate, or cannulate?  

PubMed

Ventilatory management of acute respiratory distress syndrome has evolved significantly in the last few decades. The aims have shifted from optimal gas transfer without concern for iatrogenic risks to adequate gas transfer while minimizing lung injury. This change in focus, along with improved ventilator and multiorgan system management, has resulted in a significant improvement in patient outcomes. Despite this, a number of patients develop hypoxemic respiratory failure refractory to lung-protective ventilation (LPV). The intensivist then faces the dilemma of either persisting with LPV using adjuncts (neuromuscular blocking agents, prone positioning, recruitment maneuvers, inhaled nitric oxide, inhaled prostacyclin, steroids, and surfactant) or making a transition to rescue therapies such as high-frequency oscillatory ventilation (HFOV) and/or extracorporeal membrane oxygenation (ECMO) when both these modalities are at their disposal. The lack of quality evidence and potential harm reported in recent studies question the use of HFOV as a routine rescue option. Based on current literature, the role for venovenous (VV) ECMO is probably sequential as a salvage therapy to ensure ultraprotective ventilation in selected young patients with potentially reversible respiratory failure who fail LPV despite neuromuscular paralysis and prone ventilation. Given the risk profile and the economic impact, future research should identify the patients who benefit most from VV ECMO. These choices may be further influenced by the emerging novel extracorporeal carbon dioxide removal devices that can compliment LPV. Given the heterogeneity of acute respiratory distress syndrome, each of these modalities may play a role in an individual patient. Future studies comparing LPV, HFOV, and VV ECMO should not only focus on defining the patients who benefit most from each of these therapies but also consider long-term functional outcomes. PMID:23827735

Shekar, Kiran; Davies, Andrew R; Mullany, Daniel V; Tiruvoipati, Ravindranath; Fraser, John F

2013-07-02

307

Inhaled prostacyclin and high-frequency oscillatory ventilation in a premature infant with respiratory syncytial virus-associated respiratory failure.  

PubMed

In a 29-day-old premature infant with respiratory syncytial virus (RSV) pneumonia, we have shown an additive effect of high-frequency oscillatory ventilation (HFOV) and continuous inhalation of prostacyclin (iPGI(2)) with improvement of ventilation and oxygenation. The addition of continuous inhaled iPGI(2) to HFOV was beneficial in the treatment of hypoxemic respiratory failure owing to RSV-associated pneumonia. The improvement in alveolar recruitment by increasing lung expansion by HFOV along with less ventilation-perfusion mismatch by iPGI(2) appears to be responsible for the synergistic effect and favorable clinical outcome. We conclude that the combined therapy of HFOV and continuous inhaled iPGI(2) may be considered in RSV-associated hypoxemic respiratory failure in pediatric patients. PMID:22753555

Gupta, Manoj; Guertin, Stephen; Martin, Steve; Omar, Said

2012-07-02

308

Clinical review: Liberation from mechanical ventilation  

PubMed Central

Mechanical ventilation is the defining event of intensive care unit (ICU) management. Although it is a life saving intervention in patients with acute respiratory failure and other disease entities, a major goal of critical care clinicians should be to liberate patients from mechanical ventilation as early as possible to avoid the multitude of complications and risks associated with prolonged unnecessary mechanical ventilation, including ventilator induced lung injury, ventilator associated pneumonia, increased length of ICU and hospital stay, and increased cost of care delivery. This review highlights the recent developments in assessing and testing for readiness of liberation from mechanical ventilation, the etiology of weaning failure, the value of weaning protocols, and a simple practical approach for liberation from mechanical ventilation.

El-Khatib, Mohamad F; Bou-Khalil, Pierre

2008-01-01

309

Poloxamer 188 Facilitates the Repair of Alveolus Resident Cells in Ventilator-injured Lungs  

PubMed Central

Rationale: Wounded alveolus resident cells are identified in human and experimental acute respiratory distress syndrome models. Poloxamer 188 (P188) is an amphiphilic macromolecule shown to have plasma membrane–sealing properties in various cell types. Objectives: To investigate whether P188 (1) protects alveolus resident cells from necrosis and (2) is associated with reduced ventilator-induced lung injury in live rats, isolated perfused rat lungs, and scratch and stretch–wounded alveolar epithelial cells. Methods: Seventy-four live rats and 18 isolated perfused rat lungs were ventilated with injurious or protective strategies while infused with P188 or control solution. Alveolar epithelial cell monolayers were subjected to scratch or stretch wounding in the presence or absence of P188. Measurements and Main Results: P188 was associated with fewer mortally wounded alveolar cells in live rats and isolated perfused lungs. In vitro, P188 reduced the number of injured and necrotic cells, suggesting that P188 promotes cell repair and renders plasma membranes more resilient to deforming stress. The enhanced cell survival was accompanied by improvement in conventional measures of lung injury (peak airway pressure, wet-to-dry weight ratio) only in the ex vivo–perfused lung preparation and not in the live animal model. Conclusions: P188 facilitates plasma membrane repair in alveolus resident cells, but has no salutary effects on lung mechanics or vascular barrier properties in live animals. This discordance may have pathophysiological significance for the interdependence of different injury mechanisms and therapeutic implications regarding the benefits of prolonging the life of stress-activated cells.

Plataki, Maria; Lee, Yang D.; Rasmussen, Deborah L.

2011-01-01

310

Body mass index contributes to sympathovagal imbalance in prehypertensives  

PubMed Central

Background The present study was conducted to assess the nature of sympathovagal imbalance (SVI) in prehypertensives by short-term analysis of heart rate variability (HRV) to understand the alteration in autonomic modulation and the contribution of BMI to SVI in the genesis of prehypertension. Methods Body mass index (BMI), basal heart rate (BHR), blood pressure (BP), rate pressure product (RPP) and HRV indices such as total power (TP), low-frequency power (LF), normalized LF (LFnu), high-frequency power (HF), normalized HF (HFnu), LF-HF ratio, mean heart rate (mean RR), square root of the mean squared differences of successive normal to normal intervals (RMSSD), standard deviation of normal to normal RR interval (SDNN), the number of interval differences of successive NN intervals greater than 50?ms (NN50) and the proportion derived by dividing NN50 by the total number of NN intervals (pNN50) were assessed in three groups of subjects: normotensives having normal BMI (Group 1), prehypertensives having normal BMI (Group 2) and prehypertensives having higher BMI (Group 3). SVI was assessed from LF-HF ratio and correlated with BMI, BHR, BP and RPP in all the groups by Pearson correlation. The contribution of BMI to SVI was assessed by multiple regression analysis. Results LF and LFnu were significantly increased and HF and HFnu were significantly decreased in prehypertensive subjects in comparison to normotensive subjects and the magnitude of these changes was more prominent in subjects with higher BMI compared to that of normal BMI. LF-HF ratio, the sensitive indicator of sympathovagal balance had significant correlation with BMI (P?=?0.000) and diastolic blood pressure (DBP) (P?=?0.002) in prehypertensives. BMI was found to be an independent contributing factor to SVI (P?=?0.001) in prehypertensives. Conclusions It was concluded that autonomic imbalance in prehypertensives manifested in the form of increased sympathetic activity and vagal inhibition. In prehypertensives with higher BMI, vagal withdrawal was predominant than sympathetic overactivity. Magnitude of SVI (alteration in LF-HF ratio) was linked to changes in BMI and DBP. BMI had an independent influence on LF-HF ratio. It was advised that life-style modifications such as yoga and exercise would enable achieve the sympathovagal balance and blood pressure homeostasis in prehypertensives.

2012-01-01

311

Summary of human responses to ventilation  

SciTech Connect

The effects of ventilation on indoor air quality and health is a complex issue. It is known that ventilation is necessary to remove indoor generated pollutants from indoor air or dilute their concentration to acceptable levels. But, as the limit values of all pollutants are not known, the exact determination of required ventilation rates based on pollutant concentrations and associated risks is seldom possible. The selection of ventilation rates has to be based also on epidemiological research (e.g. Seppanen et al., 1999), laboratory and field experiments (e.g. CEN 1996, Wargocki et al., 2002a) and experience (e.g. ECA 2003). Ventilation may also have harmful effects on indoor air quality and climate if not properly designed, installed, maintained and operated as summarized by Seppdnen (2003). Ventilation may bring indoors harmful substances that deteriorate the indoor environment. Ventilation also affects air and moisture flow through the building envelope and may lead to moisture problems that deteriorate the structures of the building. Ventilation changes the pressure differences over the structures of building and may cause or prevent the infiltration of pollutants from structures or adjacent spaces. Ventilation is also in many cases used to control the thermal environment or humidity in buildings. Ventilation can be implemented with various methods which may also affect health (e.g. Seppdnen and Fisk, 2002, Wargocki et al., 2002a). In non residential buildings and hot climates, ventilation is often integrated with air-conditioning which makes the operation of ventilation system more complex. As ventilation is used for many purposes its health effects are also various and complex. This paper summarizes the current knowledge on positive and negative effects of ventilation on health and other human responses. The focus of the paper is on office-type working environment and residential buildings. In the industrial premises the problems of air quality are usually more complex and case specific. They are subject to occupational safety legislation and not discussed here.

Seppanen, Olli A.; Fisk, William J.

2004-06-01

312

[Noninvasive ventilation in intensive care].  

PubMed

Non-invasive ventilation has been in use for many years to provide long-term home ventilatory support to patients with chronic respiratory failure. In recent years, it has emerged on the intensive care scene as a means of avoiding intubation in acute respiratory failure. The results of several studies indicate that such an approach can lead to a reduction in mortality and duration of hospital stay compared to conventional mechanical ventilation with endotracheal intubation. The purpose of this article is to explore the various ventilatory techniques available, the choice of respirator and ventilatory mode in various clinical conditions, and to discuss some of the logistics involved in the optimal use of this technique. PMID:9064754

Jolliet, P; Sommer-Buhler, J; Abajo, B; Chevrolet, J C

1997-01-25

313

Difficult weaning from mechanical ventilation  

Microsoft Academic Search

Difficult weaning is fortunately a rare occurrence in mechanically ventilated patients in ICU. When faced with this problem,\\u000a a vast number of factors must be carefully considered simultaneously: physiological adjustment, technical problems (tubing,\\u000a circuit resistances, ...) [13]. The most promising approach to difficult weaning to date centers on the respiratory muscle\\u000a function which represents the most common factor allowing weaning

J. C. Chevrolet

1990-01-01

314

A rare chromosome 3 imbalance and its clinical implications.  

PubMed

The duplication of chromosome 3q is a rare disorder with varying chromosomal breakpoints and consequently symptoms. Even rarer is the unbalanced outcome from a parental inv(3) resulting in duplicated 3q and a deletion of 3p. Molecular karyotyping should aid in precisely determining the length and breakpoints of the 3q+/3p- so as to better understand a child's future development and needs. We report a case of an infant male with a 57.5?Mb duplication from 3q23-qter. This patient also has an accompanying 1.7?Mb deletion of 3p26.3. The duplicated segment in this patient encompasses the known critical region of 3q26.3-q27, which is implicated in the previously reported 3q dup syndrome; however, the accompanying 3p26.3 deletion is smaller than the previously reported cases. The clinical phenotype of this patient relates to previously reported cases of 3q+ that may suggest that the accompanying 1.7?Mb heterozygous deletion is not clinically relevant. Taken together, our data has refined the location and extent of the chromosome 3 imbalance, which will aid in better understanding the molecular underpinning of the 3q syndrome. PMID:23097735

Sims, Karen; Mazzaschi, Roberto L P; Payne, Emilie; Hayes, Ian; Love, Donald R; George, Alice M

2012-10-11

315

Does Observation of Postural Imbalance Induce a Postural Reaction?  

PubMed Central

Background Several studies bring evidence that action observation elicits contagious responses during social interactions. However automatic imitative tendencies are generally inhibited and it remains unclear in which conditions mere action observation triggers motor behaviours. In this study, we addressed the question of contagious postural responses when observing human imbalance. Methodology/Principal Findings We recorded participants' body sway while they observed a fixation cross (control condition), an upright point-light display of a gymnast balancing on a rope, and the same point-light display presented upside down. Our results showed that, when the upright stimulus was displayed prior to the inverted one, centre of pressure area and antero-posterior path length were significantly greater in the upright condition compared to the control and upside down conditions. Conclusions/Significance These results demonstrate a contagious postural reaction suggesting a partial inefficiency of inhibitory processes. Further, kinematic information was sufficient to trigger this reaction. The difference recorded between the upright and upside down conditions indicates that the contagion effect was dependent on the integration of gravity constraints by body kinematics. Interestingly, the postural response was sensitive to habituation, and seemed to disappear when the observer was previously shown an inverted display. The motor contagion recorded here is consistent with previous work showing vegetative output during observation of an effortful movement and could indicate that lower level control facilitates contagion effects.

Tia, Banty; Saimpont, Arnaud; Paizis, Christos; Mourey, France; Fadiga, Luciano; Pozzo, Thierry

2011-01-01

316

Evaluating the physiological significance of respiratory sinus arrhythmia: looking beyond ventilation-perfusion efficiency  

PubMed Central

We conducted a theoretical study of the physiological significance of respiratory sinus arrhythmia (RSA), a phenomenon used as an index of cardiac vagal tone and wellbeing, whereby the heart rate (HR) increases during inspiration and decreases during expiration. We first tested the hypothesis that RSA improves gas exchange efficiency but found that although gas exchange efficiency improved with slow and deep breathing and with increased mean heart rate, this was unrelated to RSA. We then formulated and tested a new hypothesis: that RSA minimizes the work done by the heart while maintaining physiological levels of arterial carbon dioxide. We tested the new hypothesis using two methods. First, the HR for which the work is minimized was calculated using techniques from optimal control theory. This calculation was done on simplified models that we derived from a previously published model of gas exchange in mammals. We found that the calculated HR was remarkably similar to RSA and that this became more profound under slow and deep breathing. Second, the HR was prescribed and the work done by the heart was calculated by conducting a series of numerical experiments on the previously published gas exchange model. We found that cardiac work was minimized for RSA-like HR functions, most profoundly under slow and deep breathing. These findings provide novel insights into potential reasons for and benefits of RSA under physiological conditions.

Ben-Tal, A; Shamailov, S S; Paton, J F R

2012-01-01

317

Magnetic resonance imaging of pediatric lung parenchyma, airways, vasculature, ventilation, and perfusion: state of the art.  

PubMed

Magnetic resonance (MR) imaging is a noninvasive imaging modality, particularly attractive for pediatric patients given its lack of ionizing radiation. Despite many advantages, the physical properties of the lung (inherent low signal-to-noise ratio, magnetic susceptibility differences at lung-air interfaces, and respiratory and cardiac motion) have posed technical challenges that have limited the use of MR imaging in the evaluation of thoracic disease in the past. However, recent advances in MR imaging techniques have overcome many of these challenges. This article discusses these advances in MR imaging techniques and their potential role in the evaluation of thoracic disorders in pediatric patients. PMID:23830786

Liszewski, Mark C; Hersman, F William; Altes, Talissa A; Ohno, Yoshiharu; Ciet, Pierluigi; Warfield, Simon K; Lee, Edward Y

2013-07-01

318

Ventilation Perfusion Scintigraphy and Lung Function Testing to Assess Metal Stent Efficacy  

Microsoft Academic Search

Stent implantation in malignant bronchial stenoses is a highly effective method of providing symptomatic relief by restoring bron chial patency. Whether an improvement in ventilatory conditions is paralleled by an increase in blood flow and gas exchange has not yet been determined. Methods: Fourteen patients with malignant, high- grade obstruction of bronchi who had metal stent implantation were investigated. Before

Rainer W. Hauck; Christian Schulz; Rolf M. Lembeck; Deutsches Herzzentrum

319

Development of a Residential Integrated Ventilation Controller  

SciTech Connect

The goal of this study was to develop a Residential Integrated Ventilation Controller (RIVEC) to reduce the energy impact of required mechanical ventilation by 20percent, maintain or improve indoor air quality and provide demand response benefits. This represents potential energy savings of about 140 GWh of electricity and 83 million therms of natural gas as well as proportional peak savings in California. The RIVEC controller is intended to meet the 2008 Title 24 requirements for residential ventilation as well as taking into account the issues of outdoor conditions, other ventilation devices (including economizers), peak demand concerns and occupant preferences. The controller is designed to manage all the residential ventilation systems that are currently available. A key innovation in this controller is the ability to implement the concept of efficacy and intermittent ventilation which allows time shifting of ventilation. Using this approach ventilation can be shifted away from times of high cost or high outdoor pollution towards times when it is cheaper and more effective. Simulations, based on the ones used to develop the new residential ventilation requirements for the California Buildings Energy code, were used to further define the specific criteria and strategies needed for the controller. These simulations provide estimates of the energy, peak power and contaminant improvement possible for different California climates for the various ventilation systems. Results from a field test of the prototype controller corroborate the predicted performance.

Staff Scientist; Walker, Iain; Sherman, Max; Dickerhoff, Darryl

2011-12-01

320

Passive ventilation for residential air quality control  

SciTech Connect

Infiltration has long served the residential ventilation needs in North America. In Northern Europe it has been augmented by purpose-provided natural ventilation systems--so-called passive ventilation systems--to better control moisture problems in dwellings smaller than their North American counterparts and in a generally wetter climate. The growing concern for energy consumption, and the environmental impacts associated with it, has however led to tighter residential construction standards on both continents and as a result problems associated with insufficient background ventilation have surfaced. Can European passive ventilation systems be adapted for use in North American dwellings to provide general background ventilation for air quality control? This paper attempts to answer this question. The configuration, specifications and performance of the preferred European passive ventilation system--the passive stack ventilation (PSV) system--will be reviewed; innovative components and system design strategies recently developed to improve the traditional PSV system performance will be outlined; and alternative system configurations will be presented that may better serve the climatic extremes and more urban contexts of North America. While these innovative and alternative passive ventilation systems hold great promise for the future, a rational method to size the components of these systems to achieve the control and precision needed to meet the conflicting constraints of new ventilation and air tightness standards has not been forthcoming. Such a method will be introduced in this paper and an application of this method will be presented.

Axley, J.

1999-07-01

321

Particle deposition in ventilation ducts  

SciTech Connect

Exposure to airborne particles is detrimental to human health and indoor exposures dominate total exposures for most people. The accidental or intentional release of aerosolized chemical and biological agents within or near a building can lead to exposures of building occupants to hazardous agents and costly building remediation. Particle deposition in heating, ventilation and air-conditioning (HVAC) systems may significantly influence exposures to particles indoors, diminish HVAC performance and lead to secondary pollutant release within buildings. This dissertation advances the understanding of particle behavior in HVAC systems and the fates of indoor particles by means of experiments and modeling. Laboratory experiments were conducted to quantify particle deposition rates in horizontal ventilation ducts using real HVAC materials. Particle deposition experiments were conducted in steel and internally insulated ducts at air speeds typically found in ventilation ducts, 2-9 m/s. Behaviors of monodisperse particles with diameters in the size range 1-16 {micro}m were investigated. Deposition rates were measured in straight ducts with a fully developed turbulent flow profile, straight ducts with a developing turbulent flow profile, in duct bends and at S-connector pieces located at duct junctions. In straight ducts with fully developed turbulence, experiments showed deposition rates to be highest at duct floors, intermediate at duct walls, and lowest at duct ceilings. Deposition rates to a given surface increased with an increase in particle size or air speed. Deposition was much higher in internally insulated ducts than in uninsulated steel ducts. In most cases, deposition in straight ducts with developing turbulence, in duct bends and at S-connectors at duct junctions was higher than in straight ducts with fully developed turbulence. Measured deposition rates were generally higher than predicted by published models. A model incorporating empirical equations based on the experimental measurements was applied to evaluate particle losses in supply and return duct runs. Model results suggest that duct losses are negligible for particle sizes less than 1 {micro}m and complete for particle sizes greater than 50 {micro}m. Deposition to insulated ducts, horizontal duct floors and bends are predicted to control losses in duct systems. When combined with models for HVAC filtration and deposition to indoor surfaces to predict the ultimate fates of particles within buildings, these results suggest that ventilation ducts play only a small role in determining indoor particle concentrations, especially when HVAC filtration is present. However, the measured and modeled particle deposition rates are expected to be important for ventilation system contamination.

Sippola, Mark R.

2002-09-01

322

Ocean heat content and Earth's radiation imbalance. II. Relation to climate shifts  

NASA Astrophysics Data System (ADS)

In an earlier study of ocean heat content (OHC) we showed that Earth's empirically implied radiation imbalance has undergone abrupt changes. Other studies have identified additional such climate shifts since 1950. The shifts can be correlated with features in recently updated OHC data. The implied radiation imbalance may possibly alternate in sign at dates close to the climate shifts. The most recent shifts occurred during 2001-2002 and 2008-2009. The implied radiation imbalance between these dates, in the direction of ocean heat loss, was -0.03±0.06 W/m, with a possible systematic error of [-0.00,+0.09] W/m.

Douglass, D. H.; Knox, R. S.

2012-03-01

323

Gradient-enhanced FAWSETS perfusion measurements  

NASA Astrophysics Data System (ADS)

This work describes the use of custom-built gradients to enhance skeletal muscle perfusion measurements acquired with a previously described arterial spin labeling technique known as FAWSETS (flow-driven arterial water stimulation with elimination of tissue signal). Custom-built gradients provide active control of the static magnetic field gradient on which FAWSETS relies for labeling. This allows selective, 180° modulations of the phase of the perfusion component of the signal. Phase cycling can then be implemented to eliminate all extraneous components leaving a signal that exclusively reflects capillary-level perfusion. Gradient-enhancement substantially reduces acquisition time and eliminates the need to acquire an ischemic signal to quantify perfusion. This removes critical obstacles to application of FAWSETS in organs other than skeletal muscle and makes the measurements more desirable for clinical environments. The basic physical principles of gradient-enhancement are demonstrated in flow phantom experiments and in vivo utility is demonstrated in rat hind limb during stimulated exercise.

Marro, Kenneth I.; Lee, Donghoon; Hyyti, Outi M.

2005-08-01

324

Regional myocardial perfusion of cardioplegic solutions  

SciTech Connect

We compared the regional myocardial perfusion of blood cardioplegic solution (BCP) and crystalloid cardioplegic solution (CCP) in 14 mongrel dogs. Cardiopulmonary bypass was established at 28 degrees C, and a hydraulic occluder was placed around the proximal left anterior descending (LAD) coronary artery. In group 1 (N = 7) collateral coronary arteries were ligated; in group 2 (N = 7) collateral coronary arteries were left in situ. After the aorta was clamped, BCP and CCP were alternately perfused at 200 ml/min. The occluder was inflated to produce moderate, severe, and critical LAD stenosis, and regional perfusion was measured by xenon-133 washout with the Silicon Avalanche Radiation Detector. BCP infusion produced a consistently higher aortic pressure, but CCP flow was better than BCP flow under all conditions, particularly without coronary collaterals. Regional myocardial perfusion of CCP is superior to BCP.

Eugene, J.; Lyons, K.P.; Ott, R.A.; Gelezunas, V.L.; Chang, C.W.; Kowall, M.G.; Haiduc, N.J.

1987-05-01

325

Comparative evaluation of the effects of indomethacin and ibuprofen on cerebral perfusion and oxygenation in preterm infants with patent ductus arteriosus  

Microsoft Academic Search

Objective: To compare the effects on cerebral perfusion and oxygenation of intravenous ibuprofen and indomethacin as treatment for patent ductus arteriosus in preterm infants.Study design: Sixteen infants receiving mechanical ventilation (< 31 weeks gestation) with patent ductus arteriosus received either 0.2 mg\\/kg indomethacin ( n = 8) or 10 mg\\/kg ibuprofen ( n = 8) infused over 1 minute. Near-infrared

Fabio Mosca; Milena Bray; Maria Lattanzio; Monica Fumagalli; Camillo Tosetto

1997-01-01

326

[Lung damage due to mechanical ventilation].  

PubMed

Mechanical ventilation in both children and adults is still associated with development of lung injury, both short term and long term. In particular, ventilation with high tidal volumes and low positive end-expiratory pressures (PEEP) contributes significantly to development of lung injury. Suggested preventive measures consist of limiting peak inflation pressures, preventing high tidal volumes, and applying high PEEP to prevent alveolar collapse. Recent studies have demonstrated that mechanical ventilation, via stretch of lung tissue, results in an inflammatory reaction in the lungs. This is known as biotrauma. The degree of inflammation depends on the ventilator settings and mode of ventilation. This inflammatory reaction may not be limited to the lungs but, via inflammatory mediators, may cause multiple organ dysfunction as well. Future research needs to be concentrated on how to modify this ventilator induced inflammatory reaction in order to prevent lung injury as well as systemic injury. PMID:10086125

Plötz, F B; van Vught, A J

1999-01-16

327

Xenon kinetics in muscle are not explained by a model of parallel perfusion-limited compartments  

SciTech Connect

Experimental tissue gas kinetics do not follow the prediction for a single stirred perfusion-limited compartment. One hypothesis proposes that the kinetics might be explained by considering the tissue as a collection of parallel compartments, each with its own flow, reflecting the tissue microcirculatory flow heterogeneity. In this study, observed tissue gas kinetics were compared with the kinetics predicted by a model of multiple parallel compartments. Gas exchange curves were generated by recording the time course of tissue radioactivity in the intact calf muscles of anesthetized ventilated dogs exposed to step function changes of 133Xe in the inspired air for 5-h periods. Microcirculatory flow heterogeneity in the same tissue was determined by the radioactive microsphere method. Observed mean tissue transit times were on average longer than predicted by a factor of 6.7. Observed means averaged 52.1 min compared with 8.3 min predicted by the perfusion-limited model. Relative dispersions of tissue transit times were also uniformly larger than predicted. We conclude that Xe gas kinetics in intact canine skeletal muscle are not explained by a model of multiple parallel perfusion-limited compartments. Countercurrent exchange of gas between vessels is a possible explanation.

Novotny, J.A.; Mayers, D.L.; Parsons, Y.F.; Survanshi, S.S.; Weathersby, P.K.; Homer, L.D. (Naval Medical Research Institute, Bethesda, MD (USA))

1990-03-01

328

Site of pulmonary vasodilation by inhaled nitric oxide in the perfused lung  

SciTech Connect

Site of pulmonary vasodilation by inhaled nitric oxide in the perfused lung. To determine the site of inhaled nitric oxide (NO)-induced pulmonary vasodilation, a double vascular occlusion technique was used with rabbit lungs ventilated and perfused at 20 ml/min with Krebs solution containing 3% dextran and 30 {mu}M indomethacin. Inhaled NO (120 ppm for 3% min) reduced pulmonary vasoconstriction produced by U-46619 infusion (0.5 -1.2 nmol/min), significantly decreasing total resistance (RT) [1,080 {plus_minus} 51 (SE) vs. 1,545 {plus_minus} 109 mmHg-min/l; P < 0.01]. Acetylcholine infusion (ACh; 2-5 nmol/min) and nitroglycerin (NTG; 0.35 {mu}mol) likewise decreased RT. Arterial resistance (Ra) was also significantly less with inhaled NO, ACh, and NTG compared with U-46619 alone. Venous resistance (Rv), however, was unchanged. When the direction of perfusion was reversed in the lung, inhaled NO, ACh, and NTG significantly decreased RT compared with U-46619 alone, and Rv was also reduced by all three agents. After electrolysis-induced acute lung injury, inhaled NO significantly reduced both RT and Ra compared with U-46619 alone, whereas Rv was unaffected. Our results demonstrate that inhaled NO gas affects primarily the arterial (precapillary) component of the pulmonary circulation but, under conditions of extreme venous constriction, may dilate the postcapillary component as well. 25 refs., 4 figs.

Rimar, S.; Gillis, C.N. [Yale Univ. School of Medicine, New Haven, CT (United States)

1995-05-01

329

Injurious mechanical ventilation affects neuronal activation in ventilated rats  

Microsoft Academic Search

Introduction  Survivors of critical illness often have significant long-term brain dysfunction, and routine clinical procedures like mechanical\\u000a ventilation (MV) may affect long-term brain outcome. We aimed to investigate the effect of the increase of tidal volume (Vt)\\u000a on brain activation in a rat model.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Male Sprague Dawley rats were randomized to three groups: 1) Basal: anesthetized unventilated animals, 2) low Vt

Elisa María Quilez; Gemma Fuster; Jesús Villar; Carlos Flores; Octavi Martí-Sistac; Lluís Blanch; Josefina López-Aguilar

2011-01-01

330

Nontraditional modes of mechanical ventilation: progress or distraction?  

PubMed

As technology continues to develop, a wide range of novel and nontraditional modes of mechanical ventilation have become available for the management of critically ill patients. Proportional assist ventilation, neurally adjusted ventilatory assist and adaptive support ventilation are three novel modes of ventilation, which attempt to optimize patient-ventilator synchrony. Improved interactions between patient and ventilator may be important in improving clinical outcomes. Another important priority for mechanically ventilated patients is lung protection, and nontraditional modes of ventilation that may be implemented to minimize ventilator-associated lung injury include airway pressure release ventilation and high-frequency ventilation. Novel and nontraditional modes of ventilation may represent important tools in the critical care environment; however, continued investigation is needed to determine the overall impact of these various approaches on outcomes for mechanically ventilated patients. PMID:22788942

Turner, David A; Rehder, Kyle J; Cheifetz, Ira M

2012-06-01

331

Chromosomal Imbalances in Primary Lymphomas of the Central Nervous System  

PubMed Central

Twenty-two primary central nervous system lymphomas of immunocompetent adults were studied by comparative genomic hybridization. All were high-grade diffuse large B cell lymphomas. Comparative genomic hybridization revealed an average of 5.5 chromosomal changes per tumor, with gains being more common than losses (3.5 vs. 2.0). The most frequent DNA copy number changes were gains on chromosomes 1, 12, 18 (41% each), 7 (23%), and 11 (18%) and losses involving chromosomes 6 (59%), 18, and 20 (18% each). Commonly involved regions were +12q (41%), +18q (36%), +1q (32%), and +7q (23%), as well as ?6q (50%), ?6p (18%), ?17p, and ?18p (14% each). High-level gains were found on 7 chromosomes, mainly involving chromosomes 18q (23%), 12q (18%), and 1q (14%). Minimal common regions of over- and underrepresentation were found on +1q25–31, ?6q16–21, +7q11.2, +12p11.2–13, +12q12–14, +12q22–24.1, and +18q12.2–21.3. A significant correlation between loss of DNA copy numbers on chromosome 6q and shorter survival could be established (10.2 vs. 22.3 months; P < 0.05). Our findings suggest that chromosomal imbalances of primary central nervous system lymphomas are similar to those of diffuse large B cell lymphomas at other locations and are probably not related to cerebral presentation; however, they may be prognostically relevant.

Rickert, Christian H.; Dockhorn-Dworniczak, Barbara; Simon, Ronald; Paulus, Werner

1999-01-01

332

Copper Imbalances in Ruminants and Humans: Unexpected Common Ground1  

PubMed Central

Ruminants are more vulnerable to copper deficiency than humans because rumen sulfide generation lowers copper availability from forage, increasing the risk of conditions such as swayback in lambs. Molybdenum-rich pastures promote thiomolybdate (TM) synthesis and formation of unabsorbable Cu-TM complexes, turning risk to clinical reality (hypocuprosis). Selection pressures created ruminant species with tolerance of deficiency but vulnerability to copper toxicity in alien environments, such as specific pathogen–free units. By contrast, cases of copper imbalance in humans seemed confined to rare genetic aberrations of copper metabolism. Recent descriptions of human swayback and the exploratory use of TM for the treatment of Wilson’s disease, tumor growth, inflammatory diseases, and Alzheimer’s disease have created unexpected common ground. The incidence of pre–hemolytic copper poisoning in specific pathogen–free lambs was reduced by an infection with Mycobacterium avium that left them more responsive to treatment with TM but vulnerable to long-term copper depletion. Copper requirements in ruminants and humans may need an extra allowance for the “copper cost” of immunity to infection. Residual cuproenzyme inhibition in TM-treated lambs and anomalies in plasma copper composition that appeared to depend on liver copper status raise this question “can chelating capacity be harnessed without inducing copper-deficiency in ruminants or humans?” A model of equilibria between exogenous (TM) and endogenous chelators (e.g., albumin, metallothionein) is used to predict risk of exposure and hypocuprosis; although risk of natural exposure in humans is remote, vulnerability to TM-induced copper deficiency may be high. Biomarkers of TM impact are needed, and copper chaperones for inhibited cuproenzymes are prime candidates.

Suttle, Neville F.

2012-01-01

333

Perfusion visualization and analysis for pulmonary embolism  

NASA Astrophysics Data System (ADS)

Given the nature of pulmonary embolism (PE), timely and accurate diagnosis is critical. Contrast enhanced high-resolution CT images allow physicians to accurately identify segmental and sub-segmental emboli. However, it is also important to assess the effect of such emboli on the blood flow in the lungs. Expanding upon previous research, we propose a method for 3D visualization of lung perfusion. The proposed method allows users to examine perfusion throughout the entire lung volume at a single glance, with areas of diminished perfusion highlighted so that they are visible independent of the viewing location. This may be particularly valuable for better accuracy in assessing the extent of hemodynamic alterations resulting from pulmonary emboli. The method also facilitates user interaction and may help identify small peripheral sub-segmental emboli otherwise overlooked. 19 patients referred for possible PE were evaluated by CT following the administration of IV contrast media. An experienced thoracic radiologist assessed the 19 datasets with 17 diagnosed as being positive for PE with multiple emboli. Since anomalies in lung perfusion due to PE can alter the distribution of parenchymal densities, we analyzed features collected from histograms of the computed perfusion maps and demonstrate their potential usefulness as a preliminary test to suggest the presence of PE. These histogram features also offer the possibility of distinguishing distinct patterns associated with chronic PE and may even be useful for further characterization of changes in perfusion or overall density resulting from associated conditions such as pneumonia or diffuse lung disease.

Vaz, Michael S.; Kiraly, Atilla P.; Naidich, David P.; Novak, Carol L.

2005-04-01

334

Arterial endothelial changes after ischemia and perfusion.  

PubMed

The effects of six hours of ischemia and six hours of perfusion with 10 per cent dextrose and water solution, Sacks' solution and Intralipid on the endothelium of common femoral arteries in dogs were examined by light and by scanning electron microscopy and compared with normal arteries. Arteries that were ischemic or perfused with 10 per cent dextrose and water solution or Sacks' solution showed a flattening of the normal linear convolutions and extensive crater formation, with fragmentation and even complete loss of endothelial cells in many areas. The more severe changes occurred in perfused vessels. Fibrin and platelets covered the luminal surface in many areas in which there was extensive injury to the endothelium. Light microscopy revealed thickening of the internal elastic membrane and intimal fibrosis. Results of biopsies performed two weeks after perfusion showed slight, although incomplete, improvement in the structure of the endothelium. Arteries perfused with Intralipid had thickening of the intima with a proliferation of plump cells orientd linearly over the surface but with an absence of craters. Results of present studies confirm the observations of other investigators that injury to endothelial cells may be produced by ischemia and that perfusion with various solutions may produce an even more severe alteration in structure of the endothelial cell which does not return to normal within two weeks. The origin of new endothelial cells is not demonstrated by this study. PMID:1265612

Fonkalsrud, E W; Sanchez, M; Zerubavel, R; Lassaletta, L; Smeesters, C; Mahoney, A

1976-05-01

335

High-frequency percussive ventilation revisited.  

PubMed

High-frequency percussive ventilation (HFPV) has demonstrated a potential role as a rescue option for refractory acute respiratory distress syndrome and as a method for improving inhalation injury outcomes. Nevertheless, there is a lack of literature examining the practical application of HFPV theory toward either improving gas exchange or preventing possible ventilator-induced lung injury. This article will discuss the clinically pertinent aspects of HFPV, inclusive of high- and low-frequency ventilation. PMID:20616646

Allan, Patrick F; Osborn, Erik C; Chung, Kevin K; Wanek, Sandra M

336

Patterns of pulmonary perfusion scans in normal subjects  

SciTech Connect

A vital factor conditioning the usage of the pulmonary perfusion (Q) scan in the evaluation of patients suspected of pulmonary embolism is the prevalence of abnormal Q scans in subjects free of cardiopulmonary disease. Because this prevalence has not been well defined, we performed Q scans in 80 nonsmoking subjects 18 to 29 yr of age having no known active cardiopulmonary disease. Each subject underwent a history, physical examination, electrocardiogram, spirometry, and PA chest roentgenogram, followed by a 6-view Q scan. Two subjects in whom a Q defect was suspected underwent a /sup 133/Xe equilibrium-washout ventilation (V) scan. All Q scans were interpreted blindly and independently by 2 experienced readers. Seventy-nine of the 80 Q scans were read as normal. No subject demonstrated a lobar or segmental defect. One of the 80 subjects, who had a mild pectus excavatum, had a left upper lobe subsegmental defect, which was not seen on the V scan. Based on the statistical analysis of these data, no more than 3.68% of normal nonsmoking persons in this age group may have a lobar or segmental Q scan defect and no more than 6.77% may have a subsegmental defect (with 95% confidence). Therefore, our study indicated that Q scan defects, particularly lobar or segmental, are rarely present among normal nonsmokers in this age group.

Wallace, J.M.; Moser, K.M.; Hartman, M.T.; Ashburn, W.L.

1981-01-01

337

Effects of surfactant depletion on regional pulmonary metabolic activity during mechanical ventilation  

PubMed Central

Inflammation during mechanical ventilation is thought to depend on regional mechanical stress. This can be produced by concentration of stresses and cyclic recruitment in low-aeration dependent lung. Positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) allows for noninvasive assessment of regional metabolic activity, an index of neutrophilic inflammation. We tested the hypothesis that, during mechanical ventilation, surfactant-depleted low-aeration lung regions present increased regional 18F-FDG uptake suggestive of in vivo increased regional metabolic activity and inflammation. Sheep underwent unilateral saline lung lavage and were ventilated supine for 4 h (positive end-expiratory pressure = 10 cmH2O, tidal volume adjusted to plateau pressure = 30 cmH2O). We used PET scans of injected 13N-nitrogen to compute regional perfusion and ventilation and injected 18F-FDG to calculate 18F-FDG uptake rate. Regional aeration was quantified with transmission scans. Whole lung 18F-FDG uptake was approximately two times higher in lavaged than in nonlavaged lungs (2.9 ± 0.6 vs. 1.5 ± 0.3 10?3/min; P < 0.05). The increased 18F-FDG uptake was topographically heterogeneous and highest in dependent low-aeration regions (gas fraction 10–50%, P < 0.001), even after correction for lung density and wet-to-dry lung ratios. 18F-FDG uptake in low-aeration regions of lavaged lungs was higher than that in low-aeration regions of nonlavaged lungs (P < 0.05). This occurred despite lower perfusion and ventilation to dependent regions in lavaged than nonlavaged lungs (P < 0.001). In contrast, 18F-FDG uptake in normally aerated regions was low and similar between lungs. Surfactant depletion produces increased and heterogeneously distributed pulmonary 18F-FDG uptake after 4 h of supine mechanical ventilation. Metabolic activity is highest in poorly aerated dependent regions, suggesting local increased inflammation.

de Prost, Nicolas; Costa, Eduardo L.; Wellman, Tyler; Musch, Guido; Winkler, Tilo; Tucci, Mauro R.; Harris, R. Scott; Venegas, Jose G.

2011-01-01

338

Superfluid Phase Transition and Strong-Coupling Effects in an Ultracold Fermi Gas with Mass Imbalance  

NASA Astrophysics Data System (ADS)

We investigate the superfluid phase transition and effects of mass imbalance in the BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover regime of an cold Fermi gas. We point out that the Gaussian fluctuation theory developed by Nozières and Schmitt-Rink and the T-matrix theory, that are now widely used to study strong-coupling physics of cold Fermi gases, give unphysical results in the presence of mass imbalance. To overcome this problem, we extend the T-matrix theory to include higher-order pairing fluctuations. Using this, we examine how the mass imbalance affects the superfluid phase transition. Since the mass imbalance is an important key in various Fermi superfluids, such as 40K-6Li Fermi gas mixture, exciton condensate, and color superconductivity in a dense quark matter, our results would be useful for the study of these recently developing superfluid systems.

Hanai, R.; Kashimura, T.; Watanabe, R.; Inotani, D.; Ohashi, Y.

2013-05-01

339

Codigestion of manure and industrial organic waste at centralized biogas plants: process imbalances and limitations.  

PubMed

The present study focuses on process imbalances in Danish centralized biogas plants treating manure in combination with industrial waste. Collection of process data from various full-scale plants along with a number of interviews showed that imbalances occur frequently. High concentrations of ammonia or long chain fatty acids is in most cases expected to be the cause of microbial inhibitions/imbalances while foaming in the prestorage tanks and digesters is the most important practical process problem at the plants. A correlation between increased residual biogas production (suboptimal process conditions) and high fractions of industrial waste in the feedstock was also observed. The process imbalances and suboptimal conditions are mainly allowed to occur due to 1) inadequate knowledge about the waste composition, 2) inadequate knowledge about the waste degradation characteristics, 3) inadequate process surveillance, especially with regard to volatile fatty acids, and 4) insufficient pre-storage capacity causing inexpedient mixing and hindering exact dosing of the different waste products. PMID:18957768

Nielsen, H B; Angelidaki, I

2008-01-01

340

A single-to-differential low-noise amplifier with low differential output imbalance  

NASA Astrophysics Data System (ADS)

This paper presents a single-ended input differential output low-noise amplifier intended for GPS applications. We propose a method to reduce the gain/amplitude and phase imbalance of a differential output exploiting the inductive coupling of a transformer or center-tapped differential inductor. A detailed analysis of the theory of imbalance reduction, as well as a discussion on the principle of choosing the dimensions of a transformer, are given. An LNA has been implemented using TSMC 0.18 ?m technology with ESD-protected. Measurement on board shows a voltage gain of 24.6 dB at 1.575 GHz and a noise figure of 3.2 dB. The gain imbalance is below 0.2 dB and phase imbalance is less than 2 degrees. The LNA consumes 5.2 mA from a 1.8 V supply.

Lian, Duan; Wei, Huang; Chengyan, Ma; Xiaofeng, He; Yuhua, Jin; Tianchun, Ye

2012-03-01

341

Performance of ventilators for noninvasive positive-pressure ventilation in children  

Microsoft Academic Search

The aim of the present study was to evaluate the performance characteristics of all the ventilators proposed for home noninvasive positive-pressure ventilation in children in France. The ventilators (one volume-targeted, 12 pressure-targeted and four dual) were evaluated on a bench which simulated six different paediatric ventilatory patterns. For each ventilator, the quality of the inspiratory and expiratory trigger and the

B. Fauroux; K. Leroux; G. Desmarais; D. Isabey; A. Clement; F. Lofaso; B. Louis

2008-01-01

342

Ventilator-induced respiratory muscle weakness  

PubMed Central

Clinicians have long been aware that substantial lung injury results when mechanical ventilation imposes too much stress on the pulmonary parenchyma. Evidence is accruing that substantial injury may also result when the ventilator imposes too little stress on the respiratory muscles. Through adjustment of ventilator settings and administration of pharmacotherapy it is possible to render the respiratory muscles almost (or completely) inactive. Research in animals has shown that diaphragmatic inactivity produces severe injury and atrophy of muscle fibers. Human data have recently revealed that 18 to 69 hours of complete diaphragmatic inactivity associated with mechanical ventilation decreased the cross-sectional areas of diaphragmatic fibers by half or more. The atrophic injury appears to result from increased oxidative stress leading to activation of protein-degradation pathways. Scientific understanding of ventilator-induced respiratory muscle injury has not reached the stage where it is possible to undertake meaningful controlled trials and thus it is not possible to render concrete recommendations for patient management. In the meantime, clinicians are advised to select ventilator settings that avoid both excessive patient effort and also excessive respiratory muscle rest. The contour of the airway pressure waveform on a ventilator screen provides the most practical indication of patient effort, and clinicians are advised to pay close attention to the waveform as they titrate ventilator settings. Research on ventilator-induced respiratory muscle injury is in its infancy and portends to be an exciting area to follow.

Tobin, Martin J.; Laghi, Franco; Jubran, Amal

2010-01-01

343

A definition of irreversible entropy change by detailed (Im)balance of a stochastic process  

Microsoft Academic Search

Entropy changedS is defined by the “detailed imbalance” of a stochastic process describing irreversible evolution. The detailed imbalance for a pair of configurationsi andj is log(pitfij\\/Pjtfji), wherepit andpjt are the probabilities at timet andfij andfji are the transition probabilities. This quantity, averaged for alli, j transitions, is equated todS. The definition facilitates the description of entropy changes for a nonisolated

Z. Alexandrowicz

1977-01-01

344

Joint compensation of IQ imbalance and frequency offset in OFDM systems  

Microsoft Academic Search

Zero-IF receivers are gaining interest because of their potential to enable low-cost OFDM terminals. However, zero-IF receivers introduce IQ imbalance which may have a huge impact on the performance. Rather than increasing design time or component cost to decrease the IQ unbalance, an alternative is to tolerate the IQ imbalance and compensate it digitally. Current solutions require extra analog hardware

J. Tubbax; B. Come; L. Van der Perre; S. Donnay; M. Engels; M. Moonen; H. De Man

2003-01-01

345

IQ-Imbalance Compensation for OFDM in the Presence of IBI and Carrier-Frequency Offset  

Microsoft Academic Search

In this paper, we propose a frequency-domain equalization technique for orthogonal frequency division multiplexing (OFDM) transmission over frequency-selective channels. We consider the case where the receiver analog front-end suffers from IQ-imbalance and the local oscillator suffers from carrier-frequency offset (CFO). While the IQ-imbalance results in a mirroring effect, the CFO induces inter-carrier interference (ICI). In addition to ICI, we consider

Imad Barhumi; Marc Moonen

2007-01-01

346

Elective high frequency oscillatory ventilation versus conventional ventilation for acute pulmonary dysfunction in preterm infants  

Microsoft Academic Search

Background Respiratory failure due to lung immaturity is a major cause of mortality in preterm infants. Although the use of intermittent positive pressure ventilation (IPPV) in neonates with respiratory failure saves lives, its use is associated with lung injury and chronic lung disease (CLD). A newer form of ventilation called high frequency oscillatory ventilation (HFOV) has been shown to result

F. Cools; D. J. Henderson-Smart; M. Offringa; L. M. Askie

2009-01-01

347

[Home mechanical ventilation-tracheostomy ventilation, for the long-term and variation].  

PubMed

We experienced long-term ventilation for 30 patients mostly with amyotrophic lateral sclerosis (ALS). For long-term ventilation by tracheostomy positive pressure ventilation (TPPV), we must set tidal volume (TV) over 600 ml, because setting 400 ml as TV usually applied in Japan, often develops atelectasis which causes frequent or serious pneumonia. To avoid both the elevation of airway pressure and hyper ventilation, the following intervals are needed: 10 times/min for breathing frequency and 2 seconds for exhaling time. In the cases with ventilator induced lung injury (VILI), it is necessary to lower the TV and to treat with steroid pulse therapy. In the transitional stage from non-invasive positive pressure ventilation (NPPV) to TPPV, we conduct tracheostomy for suction of the sputum. In that stage, by using a cuffless tracheal canule, we can continue NPPV. As another method in that stage, we recommend biphasic management by NPPV at daytime and TPPV at nighttime with a bi-level ventilator. This method can provide certain ventilation also during sleep. When the respiratory failure proceeds further, we manage the ventilation with a bi-level ventilator on TPPV, because a bi-level ventilator is also good adapting to assist spontaneous breathing in that stage. And if the patient does not have bulbar paralysis, the patient can utter by air leakage with using bi-level ventilator and flattening the cuff of the tracheal canule. PMID:17469348

Yamamoto, Makoto

2006-12-01

348

Quantitative assessment of acute kidney injury by noninvasive arterial spin labeling perfusion MRI: a pilot study.  

PubMed

The kidneys are essential for maintaining homeostasis, are responsible for the reabsorption of water, glucose and amino acids, and filter the blood by removing waste. Acute kidney injury (AKI) is a syndrome characterized by the rapid loss of renal excretory function and the accumulation of end metabolic products of urea and creatinine. AKI is associated with the later development of chronic kidney disease and end-stage kidney disease, and may eventually be fatal. Early diagnosis of AKI and assessments of the effects of treatment, however, are challenging. The pathophysiological mechanism of AKI is thought to be the imbalance between oxygen supply and demand in the kidneys. We have assessed the ability of arterial spin labeling (ASL) perfusion magnetic resonance imaging (MRI), without the administration of contrast media, to quantify renal blood flow (RBF) non-invasively. We found that RBF was significantly lower in AKI patients than in healthy volunteers. These results suggest that ASL perfusion MRI, a noninvasive measurement of RBF, may be useful in the early diagnosis of AKI. PMID:23740361

Dong, Jian; Yang, Li; Su, Tao; Yang, XueDong; Chen, Bin; Zhang, Jue; Wang, XiaoYing; Jiang, XueXiang

2013-06-05

349

Study of IQ imbalance effect in direct-detection optical OFDM systems  

NASA Astrophysics Data System (ADS)

In-phase/quadrature-phase (IQ) imbalance can result in severe performance degradation in optical direct-detection orthogonal-frequency-division-multiplexing (DD-OFDM) systems. We build two optical back-to-back DD-OFDM systems, which implement double-sideband (DSB) and single-sideband (SSB) modulation, respectively. The tolerance to IQ imbalance of these two systems is analyzed and compared using error vector magnitude (EVM) and symbol error rate (SER). We find that, in the back-to-back case, the DSB system has stronger robustness to IQ imbalance than the SSB System. We further build two optical DD-OFDM systems each with 40-km transmission, which respectively implement DSB and SSB transmission. Similarly, we analyze and compare the tolerance to IQ imbalance of these two systems in terms of EVM and SER. We find that, however, in the case of 40-km transmission, the SSB system has stronger robustness to IQ imbalance than the DSB system. As a result, we conclude that, in the case of transmission, SSB modulation can enhance the tolerance to IQ imbalance of DD-OFDM systems.

Li, Xinying; Shao, Yufeng; Zou, Shumin; Hou, Chunning; Zheng, Xi; Liu, Xiao; Zhang, Junwen; Fang, Wuliang; Chi, Nan

2009-11-01

350

HOW THE LEED VENTILATION CREDIT IMPACTS ENERGY CONSUMPTION OF GSHP SYSTEMS A CASE STUDY FOR PRIMARY SCHOOLS  

SciTech Connect

This paper presents a study on the impacts of increased outdoor air (OA) ventilation on the performance of ground-source heat pump (GSHP) systems that heat and cool typical primary schools. Four locations Phoenix, Miami, Seattle, and Chicago are selected in this study to represent different climate zones in the United States. eQUEST, an integrated building and HVAC system energy analysis program, is used to simulate a typical primary school and the GSHP system at the four locations with minimum and 30% more than minimum OA ventilation. The simulation results show that, without an energy recovery ventilator, the 30% more OA ventilation results in an 8.0 13.3% increase in total GSHP system energy consumption at the four locations. The peak heating and cooling loads increase by 20.2 30% and 14.9 18.4%, respectively, at the four locations. The load imbalance of the ground heat exchanger is increased in hot climates but reduced in mild and cold climates.

Liu, Xiaobing [ORNL

2011-01-01

351

Near-infrared spectroscopy monitoring of cerebral oxygen during assisted ventilation  

PubMed Central

Background: Changes in the arterial partial pressure of CO2 (PaCO2) has a direct though transient effect on the cerebral vasculature and cerebral circulation. Decreased PaCO2 levels lead to vasoconstriction and can result in dangerously low levels of cerebral perfusion that resolve in 4–6 h. It is currently believed that perfusion abnormalities contribute to intraventricular hemorrhage (IVH) and periventricular leukomalacia (PVL) in the neonate. PaCO2-induced vasoconstriction may contribute to the pathology of IVH and PVL. Methods: Near-infrared spectroscopy [NIRS; (INVOS cerebral/somatic oximeter; Somanetics Corporation, Troy, MI, USA)] was utilized to determine changes in regional oxygenation (rSO2) of the brain in response to changes in ventilation in isoflurane anesthetized newborn piglets. Results: Changes in cerebral rSO2 correlated significantly with end-tidal CO2 levels and to blood flow in the common carotid artery. This correlation was significant during baseline conditions, after periods of CO2 loading and during periods of hypothermia. Conclusions: The results of the study demonstrate the utility of NIRS to accurately reflect changes in cerebral oxygenation and flow to the brain in response to changes in CO2 levels in anesthetized, ventilated neonatal piglets. The use of NIRS may provide an early alert of low levels of cerebral blood flow and brain oxygenation, potentially helping in preventing the progression of IVH or PVL in the neonate.

Booth, Erin A.; Dukatz, Christopher; Sood, Beena G; Wider, Michael

2011-01-01

352

E4021, a selective phosphodiesterase 5 inhibitor, potentiates the vasodilator effect of inhaled nitric oxide in isolated perfused rat lungs.  

PubMed

To test whether E4021, a potent selective cyclic guanosine 3'-5'-monophosphate (cGMP) phosphodiesterase inhibitor, causes pulmonary vasodilation and whether it enhances the vasodilator action of inhaled nitric oxide (NO), we studied its effects on pulmonary vascular tone and inhaled NO-induced pulmonary vasodilation in isolated perfused rat lungs. Lungs were perfused at a constant flow rate with salt-Ficoll solution and ventilated with air plus 5% CO2. After equilibration, vasodilator responses to either E4021, inhaled NO, or both were evaluated under conditions of increased perfusion pressure induced by infusion of U46619. E4021 had no effect on the baseline perfusion pressure, whereas it caused dose-dependent pulmonary vasodilation when the vasomotor tone was increased by U46619. Inhaled 1, 5, and 20 ppm NO reduced the increased perfusion pressure by 60+/-5%, 83+/-3%, and 92+/-2%, respectively. Pretreatment with E4021 significantly potentiated the vasodilator effect of 1 ppm NO (from 53+/-6% to 71+/-2%; p < 0.05) but did not alter that of 5 ppm NO (from 77+/-3% to 78+/-4%; p > 0.05). In addition, pretreatment with E4021 significantly augmented the vasodilator response to sodium nitroprusside but not to isoproterenol. These results indicate that E4021 causes pulmonary vasodilation and potentiates the vasodilator effect of low concentrations of inhaled NO, probably through a cGMP-dependent mechanism in salt-solution perfused rat lungs. We conclude that E4021 may possibly be useful for the treatment of pulmonary hypertension, either alone or in combination with inhaled NO. PMID:10218733

Ohnishi, M; Oka, M; Muramatsu, M; Sato, K; Kira, S; Fukuchi, Y

1999-04-01

353

GPU-accelerated voxelwise hepatic perfusion quantification  

NASA Astrophysics Data System (ADS)

Voxelwise quantification of hepatic perfusion parameters from dynamic contrast enhanced (DCE) imaging greatly contributes to assessment of liver function in response to radiation therapy. However, the efficiency of the estimation of hepatic perfusion parameters voxel-by-voxel in the whole liver using a dual-input single-compartment model requires substantial improvement for routine clinical applications. In this paper, we utilize the parallel computation power of a graphics processing unit (GPU) to accelerate the computation, while maintaining the same accuracy as the conventional method. Using compute unified device architecture-GPU, the hepatic perfusion computations over multiple voxels are run across the GPU blocks concurrently but independently. At each voxel, nonlinear least-squares fitting the time series of the liver DCE data to the compartmental model is distributed to multiple threads in a block, and the computations of different time points are performed simultaneously and synchronically. An efficient fast Fourier transform in a block is also developed for the convolution computation in the model. The GPU computations of the voxel-by-voxel hepatic perfusion images are compared with ones by the CPU using the simulated DCE data and the experimental DCE MR images from patients. The computation speed is improved by 30 times using a NVIDIA Tesla C2050 GPU compared to a 2.67 GHz Intel Xeon CPU processor. To obtain liver perfusion maps with 626 400 voxels in a patient's liver, it takes 0.9 min with the GPU-accelerated voxelwise computation, compared to 110 min with the CPU, while both methods result in perfusion parameters differences less than 10-6. The method will be useful for generating liver perfusion images in clinical settings.

Wang, H.; Cao, Y.

2012-09-01

354

GPU-Accelerated Voxelwise Hepatic Perfusion Quantification  

PubMed Central

Voxelwise quantification of hepatic perfusion parameters from dynamic contrast enhanced (DCE) imaging greatly contributes to assessment of liver function in response to radiation therapy. However, the efficiency of the estimation of hepatic perfusion parameters voxel-by-voxel in the whole liver using a dual-input single-compartment model requires substantial improvement for routine clinical applications. In this paper, we utilize the parallel computation power of a graphics processing unit (GPU) to accelerate the computation, while maintaining the same accuracy as the conventional method. Using CUDA-GPU, the hepatic perfusion computations over multiple voxels are run across the GPU blocks concurrently but independently. At each voxel, non-linear least squares fitting the time series of the liver DCE data to the compartmental model is distributed to multiple threads in a block, and the computations of different time points are performed simultaneously and synchronically. An efficient fast Fourier transform in a block is also developed for the convolution computation in the model. The GPU computations of the voxel-by-voxel hepatic perfusion images are compared with ones by the CPU using the simulated DCE data and the experimental DCE MR images from patients. The computation speed is improved by 30 times using a NVIDIA Tesla C2050 GPU compared to a 2.67 GHz Intel Xeon CPU processor. To obtain liver perfusion maps with 626400 voxels in a patient’s liver, it takes 0.9 min with the GPU-accelerated voxelwise computation, compared to 110 min with the CPU, while both methods result in perfusion parameters differences less than 10?6. The method will be useful for generating liver perfusion images in clinical settings.

Wang, H; Cao, Y

2012-01-01

355

The effect of CO sub 2 on pulmonary artery pressure (P sub pa ) over time in the isolated perfused rabbit lung  

SciTech Connect

The isolated perfused rabbit lung model is used in studies of pulmonary hemodynamics, structure, and function under conditions closely resembling those which occur in living animals. The purpose of this study is to observe changes in P{sub pa} in response to differing concentrations of CO{sub 2} over time. After rapid exsanguination a tracheostomy was performed. Cannulas were secured in the main pulmonary artery and the left atrium. The lungs were perfused with Krebs-Henseleit buffer mixed with blood at a rate of 120 ml/min with recirculation. The temperature of the perfusate was maintained between 35 and 38C. The lungs were then ventilated with 5% CO{sub 2} in air with a tidal volume of 10 ml/kg at 20 breaths/min. CO{sub 2} was altered randomly by ventilating the lungs 2, 5 or 10% CO{sub 2} in air. Metabolic acidosis was corrected with NaHCO{sub 3}. In the first two hour period after lung perfusion was begun, the model was allowed to stabilize at each CO{sub 2} concentration, and pH, pCO{sub 2}, pO{sub 2}, and base excess were determined at each P{sub pa}. All measurements were repeated in the second period beginning two hours after lung perfusion was started. P{sub pa} was plotted against pH for each animal in both early and late phases, and simple regression analysis was performed. The slopes and the y intercepts for the data sets in both groups were compared using one factor ANOVA, and were found to be significantly different, implying a statistical difference between regression lines. In the early phase this model behaves like the in vivo lung, i.e. hypercarbia appears to increase, while hypocarbia decreases, P{sub pa}. During the late phase of lung perfusion the opposite occurs.

Reynolds, P.; Shayevitz, J. (Univ. of Michigan, Ann Arbor (United States))

1991-03-11

356

[Outcomes after Total Arch Replacement using Antegrade Selective Cerebral Perfusion under Right Axillary Artery Perfusion].  

PubMed

Although the outcomes of total arch replacement have been improving, the prevention of cerebral infarction is still an important consideration in aortic arch surgery. Herein, we reviewed our experience with total arch replacement using antegrade selective cerebral perfusion under right axillary artery perfusion. Between January 2002 and March 2013, total arch replacement was performed for 125 patients including 31 patients with acute aortic dissection. An 8 mm polyester grafts was sutured to the axillary artery through the right subclavicular incision and was connected to cardiopulmonary bypass circuit. Antegrade selective cerebral perfusion under hypothermic circulatory arrest was initiated using right axillary artery perfusion. Postoperative cerebral infarction occurred in 5.6% of patients. Hospital mortality rate was 3.2%. The 5-year rate of freedom from aortic event was 83%. The 5-year survival rate was 75%. We consider that right axillary artery perfusion is advantageous for preventing cerebral infarction in total arch replacement. PMID:24105111

Nishimura, Yoshiharu; Honda, Kentaro; Yuzaki, Mitsuru; Nakai, Takeo; Uchita, Shunji; Okamura, Yoshitaka

2013-10-01

357

46 CFR 185.352 - Ventilation of gasoline machinery spaces.  

Code of Federal Regulations, 2011 CFR

... Ventilation of gasoline machinery spaces. 185.352 Section 185.352 ...Ventilation of gasoline machinery spaces. The mechanical exhaust for the ventilation of a gasoline machinery space, required by §...

2011-10-01

358

46 CFR 154.1205 - Mechanical ventilation system: Standards.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Mechanical ventilation system: Standards. 154...Construction and Equipment Cargo Area: Mechanical Ventilation System § 154.1205 Mechanical ventilation system: Standards....

2010-10-01

359

46 CFR 92.15-10 - Ventilation for closed spaces.  

Code of Federal Regulations, 2010 CFR

... 2009-10-01 2009-10-01 false Ventilation for closed spaces. 92.15-10 Section...MISCELLANEOUS VESSELS CONSTRUCTION AND ARRANGEMENT Ventilation § 92.15-10 Ventilation for closed spaces. (a) Except...

2009-10-01

360

Mechanical Ventilation and the Kidney  

PubMed Central

Acute lung injury (ALI) and acute kidney injury (AKI) are complications often encountered in the setting of critical illness. Both forms of end-organ injury commonly occur in similar settings of systemic inflammatory response syndrome, shock, and evolving multiple organ dysfunction. Recent elucidation of the pathobiology of critical illness has led to a more basic mechanistic understanding of the complex interplay between injured organs in patients with multiple organ dysfunction syndrome; this has been aptly called ‘the slippery slope of critical illness’ [Kidney Int Suppl 1998;66:S25–S33]. Distant organ effects of apparently isolated injuries to the lungs, gut, and kidneys have all been discovered in recent years. In this article, we will review the harmful bidirectional interaction between ALI and AKI, which appears to be a common clinical syndrome with routine clinical implications. We will review the current understanding of lung-kidney interactions from both perspectives, including the renal effects of ALI and mechanical ventilation, and the pulmonary sequelae of AKI. In this review of the emerging evidence of deleterious bidirectional organ cross talk between lung and kidney, we will focus on the role of ventilator-induced kidney injury in the pathogenesis of AKI in patients with ALI.

Koyner, Jay L.; Murray, Patrick T.

2010-01-01

361

Dynamic Behaviour of Ventilated Hydrofoils.  

NASA Astrophysics Data System (ADS)

In certain types of pumping applications oscillations are induced by operation with liquids containing a free gas load. In order to understand the physics of this process, a series of tests with a ventilated A 2D NACA 0015 hydrofoil were performed in the water tunnel at the St. Anthony Falls Laboratory of the University of Minnesota. The special bubble removal feature of the water tunnel allowed continuous ventilation without experiencing visible bubbles upstream the hydrofoil. These studies build on previous work on cavitation-induced oscillations. Gas injection studies were made over a range of gas flow rates and test section pressure. The results clearly show that lift oscillations increase in intensity when the gas load is increased. The point of maximum unsteadiness is also associated the rapid decline of the foil performance as measured as average lift. Further increase of the gas injection load gives a steady behaviour with almost no lift. These experiments are compared with traditional cavitation experiments. The similarities between gas injection- and cavitation induced unsteadiness on the hydrofoil are many, but the amplitude of lift oscillations found on the foil with gas injection corresponds to about 50% of that found for cavitating hydrofoils. The fact that the oscillations are periodic leads to the consideration of both passive and active control.

Kjeldsen, Morten; Arndt, Roger; Wosnik, Martin

2006-11-01

362

In Vivo MR Imaging of Pulmonary Perfusion and Gas Exchange in Rats via Continuous Extracorporeal Infusion of Hyperpolarized 129Xe  

PubMed Central

Background Hyperpolarized (HP) 129Xe magnetic resonance imaging (MRI) permits high resolution, regional visualization of pulmonary ventilation. Additionally, its reasonably high solubility (>10%) and large chemical shift range (>200 ppm) in tissues allow HP 129Xe to serve as a regional probe of pulmonary perfusion and gas transport, when introduced directly into the vasculature. In earlier work, vascular delivery was accomplished in rats by first dissolving HP 129Xe in a biologically compatible carrier solution, injecting the solution into the vasculature, and then detecting HP 129Xe as it emerged into the alveolar airspaces. Although easily implemented, this approach was constrained by the tolerable injection volume and the duration of the HP 129Xe signal. Methods and Principal Findings Here, we overcome the volume and temporal constraints imposed by injection, by using hydrophobic, microporous, gas-exchange membranes to directly and continuously infuse 129Xe into the arterial blood of live rats with an extracorporeal (EC) circuit. The resulting gas-phase 129Xe signal is sufficient to generate diffusive gas exchange- and pulmonary perfusion-dependent, 3D MR images with a nominal resolution of 2×2×2 mm3. We also show that the 129Xe signal dynamics during EC infusion are well described by an analytical model that incorporates both mass transport into the blood and longitudinal relaxation. Conclusions Extracorporeal infusion of HP 129Xe enables rapid, 3D MR imaging of rat lungs and, when combined with ventilation imaging, will permit spatially resolved studies of the ventilation-perfusion ratio in small animals. Moreover, EC infusion should allow 129Xe to be delivered elsewhere in the body and make possible functional and molecular imaging approaches that are currently not feasible using inhaled HP 129Xe.

Cleveland, Zackary I.; Moller, Harald E.; Hedlund, Laurence W.; Nouls, John C.; Freeman, Matthew S.; Qi, Yi; Driehuys, Bastiaan

2012-01-01

363

Control Applications in Artificial Ventilation (Invited Paper)  

Microsoft Academic Search

The history of artificial ventilation is closely related to the origin of anesthesia. After the introduction of ether for use as a anesthetic drug in Boston, USA, in 1846, the need for artificial ventilation soon became evident. Soon after, the first medical devices allowing proper dosing of the agents, guaranteeing pressure control of the carrier gases and offering bags for

Marian Walter; Steffen Leonhardt

364

Increasing energy efficiency of mine ventilation systems  

SciTech Connect

Every year the US mining industry spends millions of dollars on underground ventilation systems. Potential motor-driven system energy savings can be realized by using mature, proven, and cost-effective technologies. Improved energy efficiency also leads to reduced environmental emissions. This paper promotes a systems approach to increase the energy efficiency in mine ventilation.

Papar, Riyaz; Szady, A.; Huffer, W.D.; Martin V.; McKane, A.T.

1999-06-01

365

Daytime mechanical ventilation in chronic respiratory insufficiency  

Microsoft Academic Search

Chronic respiratory insufficiency (CRI) is associated with nocturnal hypoventilation. Treatment with noninvasive mechanical ventilation (NIMV) per- formed overnight relieves symptoms of hypoventilation and improves daytime blood gases in CRI. In order to test whether the efficacy of NIMV depends on it being applied during sleep, we conducted a prospective case-controlled study comparing daytime mechanical ventilation (dMV) in awake patients with

B. Schönhofer; M. Geibel; M. Sonneborn; P. Haidl; D. Köhler

1997-01-01

366

Tracheostomy and home ventilation in children  

Microsoft Academic Search

The last 30 years have brought a significant emphasis on home care for ventilator-dependent children. While the movement was driven by the desire to minimize healthcare costs, the advancements in medical knowledge and technology, and the change in the perception of a ventilator-dependent child have offered a fertile environment for the development of programs that support the chronic care of

Raouf S. Amin; Cynthia M. Fitton

2003-01-01

367

Noninvasive Ventilation for Acute Respiratory Failure  

Microsoft Academic Search

Noninvasive ventilation for acute respiratory failure. L. Brochard, J. Mancebo, M.W. Elliott. #ERS Journals Ltd 2002. ABSTRACT: Noninvasive ventilation (NIV) has emerged as a significant advance in the management of respiratory failure. There is now a wide body of prospective randomized-controlled trial data to support its use, particularly in the management of patients with acute or respiratory failure due to

L. Brochard; J. Mancebo; M. W. Elliott

2002-01-01

368

Survey of ventilation rates in office buildings  

Microsoft Academic Search

Building ventilation is a primary determinant of indoor air quality in buildings as it impacts indoor contaminant concentrations and occupant comfort. However, relatively few measurements of office building ventilation performance have been conducted, and those data that exist generally have not employed consistent measurement methods and have not involved representative collections of buildings. The US Environmental Protection Agency (EPA) Building

Andrew K. Persily; Josh Gorfain; Greg Brunner

2006-01-01

369

Liquid ventilation attenuates pulmonary oxidative damage  

Microsoft Academic Search

Purpose: Liquid perfluorochemicals reduce the production of reaction oxygen species by alveolar macrophages. We sought to determine whether the use of liquid perfluorochemicals in vivo during liquid ventilation would attenuate oxidative damage to the lung.Materials and Methods: Healthy infant piglets (n = 16) were instrumented for mechanical ventilation and received intravenous oleic acid to create an acute lung injury. The

David M. Steinhorn; Michele C. Papo; Alexandre T. Rotta; Ahmed Aljada; Bradley P. Fuhrman; Paresh Dandona

1999-01-01

370

Commissioning Ventilated Containment Systems in the Laboratory  

SciTech Connect

This Best Practices Guide focuses on the specialized approaches required for ventilated containment systems, understood to be all components that drive and control ventilated enclosures and local exhaust systems within the laboratory. Geared toward architects, engineers, and facility managers, this guide provides information about technologies and practices to use in designing, constructing, and operating operating safe, sustainable, high-performance laboratories.

Not Available

2008-08-01

371

Performance of Ventilation Systems in Residential Buildings.  

National Technical Information Service (NTIS)

The aim of the study was to gather information on the performance of ventilation systems in residential buildings. The effect of the ventilation on health, comfort and satisfaction was also studied. Data was also collected of the fullfilment of National B...

R. Roennberg R. Ruotsalainen A. Majanen

1989-01-01

372

NUMERICAL EVALUATION OF HYBRID VENTILATION CONTROL STRATEGIES  

Microsoft Academic Search

This paper deals with the development and the evaluation of hybrid ventilation control strategies, using both natural and mechanical modes, in residential buildings using a graphical simulation tool. The description of a library of airflow components and macroscopic pollutants models used to simulate the demand controlled ventilation based on indoor pollutant concentrations is provided. The paper discusses the issue of

David Jreijiry; Ahmad Husaunndee; Christian Inard

2005-01-01

373

Infiltration in ASHRAE's Residential Ventilation Standards  

SciTech Connect

The purpose of ventilation is to dilute or remove indoor contaminants that an occupant could be exposed to. It can be provided by mechanical or natural means. ASHRAE Standards including standards 62, 119, and 136 have all considered the contribution of infiltration in various ways, using methods and data from 20 years ago. The vast majority of homes in the United States and indeed the world are ventilated through natural means such as infiltration caused by air leakage. Newer homes in the western world are tight and require mechanical ventilation. As we seek to provide acceptable indoor air quality at minimum energy cost, it is important to neither over-ventilate norunder-ventilate. Thus, it becomes critically important to correctly evaluate the contribution infiltration makes to both energy consumption and equivalent ventilation. ASHRAE Standard 62.2 specifies how much mechanical ventilation is considered necessary to provide acceptable indoor air quality, but that standard is weak on how infiltration can contribute towards meeting the total requirement. In the past ASHRAE Standard 136 was used to do this, but new theoretical approaches and expanded weather data have made that standard out of date. This article will describe how to properly treat infiltration as an equivalent ventilation approach and then use new data and these new approaches to demonstrate how these calculations might be done both in general and to update Standard 136.

Sherman, Max

2008-10-01

374

YMP Engineered Barrier Systems Scaled Ventilation Testing  

SciTech Connect

Yucca Mountain, approximately 100 miles northwest of Las Vegas, Nevada, has been selected as the site for the nation's first geologic repository for high level nuclear waste. The Yucca Mountain Project (YMP) is currently developing the design for the underground facilities. Ventilation is a key component of the design as a way to maintain the desired thermal conditions in the emplacement drifts prior to closure. As a means of determining the effects of continuous ventilation on heat removal from the emplacement drifts two series of scaled ventilation tests have been performed. Both test series were performed in the DOE/North Las Vegas Atlas facility. The tests provided scaled (nominally 25% of the full scale emplacement drift design) thermal and flow process data that will be used to validate YMP heat and mass transport codes. The Phase I Ventilation Test series evaluated the ability of ambient ventilation air to remove energy under varying flow and input power conditions. The Phase II Ventilation Test series evaluated the ability of pre-conditioned ventilation air to remove energy under varying flow, input temperature and moisture content, and simulated waste package input power conditions. Twenty-two distinct ventilation tests were run.

S.D. Dunn; B. Lowry; B. Walsh; J.D. Mar; C. Howard; R. Johnston; T. Williams

2002-11-22

375

Thermofluid-dynamic analysis of ventilated facades  

Microsoft Academic Search

Ventilated facades can be used in cases of renovation of existing buildings and new buildings to improve both the thermal performance of building, and external architectural skin. The energy advantage provided by the ventilated facades during the summer is the reduction of the heat load due to the combined effect of the shading of the external wall and the air

F. Patania; A. Gagliano; F. Nocera; A. Ferlito; A. Galesi

2010-01-01

376

HVAC (heating, ventilation, air conditioning) literature in Japan: A critical review  

SciTech Connect

Japanese businessmen in the heating, ventilation, air conditioning, and refrigeration (HVACandR) industry consider the monitoring of technical and market developments in the United States to be a normal part of their business. In contrast, efforts by US businessmen to monitor Japanese HVAC and R developments are poorly developed. To begin to redress this imbalance, this report establishes the groundwork for a more effective system for use in monitoring Japanese HVAC and R literature. Discussions of a review of the principal HVAC and R publications in Japan and descriptions of the type of information contained in each of those publications are included in this report. Since the Japanese HVAC and R literature is abundant, this report also provides practical suggestions on how a researcher or research manager can limit the monitoring effort to the publications and type of information that would most likely be of greatest value.

Hane, G.J.

1988-02-01

377

Perfusion harmonic imaging of the human brain  

NASA Astrophysics Data System (ADS)

The fast visualisation of cerebral microcirculation supports diagnosis of acute cerebrovascular diseases. However, the commonly used CT/MRI-based methods are time consuming and, moreover, costly. Therefore we propose an alternative approach to brain perfusion imaging by means of ultrasonography. In spite of the low signal/noise-ratio of transcranial ultrasound and the high impedance of the skull, flow images of cerebral blood flow can be derived by capturing the kinetics of appropriate contrast agents by harmonic ultrasound image sequences. In this paper we propose three different methods for human brain perfusion imaging, each of which yielding flow images indicating the status of the patient's cerebral microcirculation by visualising local flow parameters. Bolus harmonic imaging (BHI) displays the flow kinetics of bolus injections, while replenishment (RHI) and diminution harmonic imaging (DHI) compute flow characteristics from contrast agent continuous infusions. RHI measures the contrast agents kinetics in the influx phase and DHI displays the diminution kinetics of the contrast agent acquired from the decay phase. In clinical studies, BHI- and RHI-parameter images were found to represent comprehensive and reproducible distributions of physiological cerebral blood flow. For DHI it is shown, that bubble destruction and hence perfusion phenomena principally can be displayed. Generally, perfusion harmonic imaging enables reliable and fast bedside imaging of human brain perfusion. Due to its cost efficiency it complements cerebrovascular diagnostics by established CT/MRI-based methods.

Metzler, Volker H.; Seidel, Guenter; Wiesmann, Martin; Meyer, Karsten; Aach, Til

2003-05-01

378

Differences in regional myocardial perfusion, metabolism, MVO2, and edema after coronary sinus machine perfusion preservation of canine hearts.  

PubMed

Machine perfusion improves solid organ preservation for transplantation. We have demonstrated that antegrade perfusion preservation of hearts is superior to cold storage but may be limited by aortic valve incompetence. We hypothesized that retrograde perfusion (RP) through the coronary sinus may provide more reliable perfusate delivery to the heart. This study was designed to determine the optimal perfusion parameters and evaluate regional flow after RP of canine hearts. After donor cardiectomy, canine hearts (n = 6) were established in a perfusion device (LifeCradle, Organ Transport Systems, Inc., Frisco, TX) through a coronary sinus catheter. Hearts were perfused at 5°C over flow rates from 10 to 35 ml/100 g myocardium/min for 20 minutes at each flow rate. Colored microspheres were used to quantify tissue perfusion. Oxygen consumption (MVO(2)) and perfusion parameters were measured. At end-perfusion, tissue was collected for proton magnetic resonance spectroscopy ((1)H MRS), microsphere analysis, and determination of myocardial edema. MVO(2) increased up to flow rates of 20 ml/100 g/min. Right ventricular (RV) perfusion was reduced at all flow rates. Increased lactate/alanine ratios by (1)H MRS and reduced myocardial water content were noted in RV samples. RP results in excellent left ventricular (LV) perfusion. RV perfusion is reduced and oxidative metabolism in the right ventricle may not be maintained by RP. Further studies to evaluate effects of reduced RV perfusion by RP on functional recovery after transplantation are warranted. PMID:22036719

Cobert, Michael L; Merritt, Matthew E; West, LaShondra M; Jessen, Michael E; Peltz, Matthias

379

Mine ventilation and air conditioning. 3. edition  

SciTech Connect

This revised edition presents an engineering design approach to ventilation and air conditioning as part of the comprehensive environmental control of the mine atmosphere. It provides an in-depth look, for practitioners who design and operate mines, into the health and safety aspects of environmental conditions in the underground workplace. The contents include: Environmental control of the mine atmosphere; Properties and behavior of air; Mine air-quality control; Mine gases; Dusts and other mine aerosols; Mine ventilation; Airflow through mine openings and ducts; Mine ventilation circuits and networks; Natural ventilation; Fan application to mines; Auxiliary ventilation and controlled recirculation; Economics of airflow; Control of mine fires and explosions; Mine air conditioning; Heat sources and effect in mines; Mine air conditioning systems; Appendices; References; Answers to selected problems; and Index.

Hartman, H.L. [Univ. of Alabama, University, AL (United States); Mutmansky, J.M.; Ramani, R.V. [Pennsylvania State Univ., University Park, PA (United States); Wang, Y.J. [West Virginia Univ., Morgantown, WV (United States)

1998-12-31

380

[Non-invasive mechanical ventilation in COPD].  

PubMed

Non-invasive mechanical ventilation is the preferred method for the treatment of acute respiratory failure in patients with chronic obstructive pulmonary disease (COPD). Primary contraindications and stopping criteria must be regarded to avoid delaying endotracheal intubation. The primary interface is usually a nasal-oral mask. Cautious sedation can facilitate non-invasive ventilation in some patients. Under certain circumstances non-invasive ventilation may enable successful extubation in COPD patients with prolonged weaning. COPD patients can also benefit from preventive non-invasive ventilation in order to avoid re-intubation after a planned extubation. Domiciliary nocturnal non-invasive ventilation is an option for some patients with COPD in chronic hypercapnic respiratory failure. This treatment should be established in a specialised unit. PMID:22415450

Funk, G-C

2012-03-15

381

[Lung protective ventilation - pathophysiology and diagnostics].  

PubMed

Mechanical ventilation may lead to lung injury depending on the ventilatory settings (e.g. pressure amplitudes, endexpiratory pressures, frequency) and the length of mechanical ventilation. Particularly in the inhomogeneously injured lungs of ARDS patients, alveolar overextension results in volutrauma, cyclic opening and closure of alveolar units in atelectrauma. Particularly important appears to be the fact that these processes may also cause biotrauma, i.e. the ventilator-induced hyperactivation of inflammatory responses in the lung. These side effects are reduced, but not eliminated with the currently recommended ventilation strategy with a tidal volume of 6 ml/kg idealized body weight. It is our hope that in the future optimization of ventilator settings will be facilated by bedside monitoring of novel indices of respiratory mechanics such as the stress index or the Slice technique, and by innovative real-time imaging technologies such as electrical impedance tomography. PMID:18563672

Uhlig, Stefan; Frerichs, Inéz

2008-06-01

382

[New methods of artificial respiratory ventilation].  

PubMed

High frequency ventilation, a new nonconventional method, has been introduced into clinical practice also in Czechoslovakia, where mainly high frequency jet ventilation (HFJV) is being developed. The HFJ ventilator Best-2 (Konstrukta, Trencín) and Chirajet (Chirana, Stará Turá) which enable HFJV with a multijet generator are used. These equipments reduce inadvertent positive end expiratory pressure by means of an expiration jet and are so designed that Brychta's impulse and expulse regimen can be used to advantage at programmed lavage of the lungs and at selective ventilation of individual parts of the lungs. The paper presents the basic principles of HFJV as well as the author's experience in using this method of ventilation in experimental animals. PMID:2207733

Javorka, K

1990-08-01

383

Adaptive complete suppression of imbalance vibration in AMB systems using gain phase modifier  

NASA Astrophysics Data System (ADS)

Synchronous vibration can be caused by rotor imbalance in high-speed rotors of momentum exchange devices, and the imbalance vibration is the main disturbance for attitude control of spacecrafts. Active magnetic bearing (AMB) is widely used in momentum exchange devices due to its active vibration control ability. To suppress the imbalance vibration completely, an adaptive control approach based on the AMB is proposed. First, dynamics of the AMB rotor with both static imbalance and dynamic imbalance are introduced, and the model of power amplifier is particularly analyzed. Large temperature change range and overpowering cosmic ray will induce considerable errors and variations in parameters of the power amplifier, which has to work in space for about ten years. Therefore, adaptive compensation should be made for these errors and variations. Conditions, on which the imbalance vibration can be completely suppressed, are analyzed, and the results show that these conditions can be satisfied with notch filters and feedforward compensations (FFCs). However, the FFC contains an inverse function of the power amplifier, whose errors and variations can result in gain and phase differences and changes between the output voltage of the controller and the actual output current of the power amplifier. Consequently, the FFC becomes inaccurate, and residual vibration occurs. Finally, a gain phase modifier (GPM) is proposed to form two closed loops to tune the gain and phase of the FFC adaptively and precisely. The effectiveness of the proposed approach has been demonstrated by simulations and experiments. Compared with the existing methods, this method can achieve adaptive complete suppression of the imbalance vibration unaffected by the errors and variations of the power amplifier.

Fang, Jiancheng; Xu, Xiangbo; Tang, Jiqiang; Liu, Hu

2013-11-01

384

Long-Term Ventilation for High-Level Tetraplegia: A Report of 2 Cases of Noninvasive Positive-Pressure Ventilation  

Microsoft Academic Search

Toki A, Tamura R, Sumida M. Long-term ventilation for high-level tetraplegia: a report of 2 cases of noninvasive positive-pressure ventilation.Ventilator-dependent patients with tetraplegia rarely use noninvasive positive-pressure ventilation (NPPV) for long-term ventilation. We report 2 patients with high-level traumatic tetraplegia who were able to return home after being changed from traditional ventilation to NPPV. When they were referred to our

Akiko Toki; Risa Tamura; Mikio Sumida

2008-01-01

385

Regional comparison of technetium-99m DTPA aerosol and radioactive gas ventilation (xenon and krypton) studies in patients with suspected pulmonary embolism  

SciTech Connect

The regional distribution of (99mTc)DTPA aerosol was compared with that of /sup 133/Xe (n = 30) and krypton (n = 24) in a group of patients with suspected pulmonary embolism. All patients had an aerosol study using a recently available commercial generator system, a ventilation study with one of the gases, and perfusion imaging. Regional information was assessed visually on xenon, krypton, and aerosol studies independently by considering each lung as three equal-sized zones. In addition, gas ventilation findings peripheral to regions of aerosol turbulence (hot spots) were evaluated. Only 64% of the zones were in complete agreement on xenon and aerosol. Most of the discordance between xenon and aerosol was accounted for by minor degrees of /sup 133/Xe washout retention in zones that appeared normal in the aerosol study. An agreement rate of 85% was noted between 81mKr and aerosol regionally. The regions of discordance between aerosol and gas studies, however, usually were associated with unimpressive perfusion defects that did not change the scintigraphic probability for pulmonary embolism in any patient. Regarding zones of aerosol hyperdeposition, 76% had associated washout abnormalities on xenon; however, there was no correlation between the presence of these abnormalities or perfusion abnormalities. The results confirm the high sensitivity of /sup 133/Xe washout imaging, but suggest that radioaerosol imaging will detect most parenchymal abnormalities associated with perfusion defects of significance.

Ramanna, L.; Alderson, P.O.; Waxman, A.D.; Berman, D.S.; Brachman, M.B.; Kroop, S.A.; Goldsmith, M.; Tanasescu, D.E.

1986-09-01

386

Cerebral perfusion changes in chronic subdural hematoma.  

PubMed

Abstract Chronic subdural hematoma is a frequent disorder in the elderly. Although intensively investigated, numerous aspects, including the pathophysiology of clinical symptoms, remain unclear. Perfusion deficits are likely to induce the transient neurologic symptoms seen in chronic subdural hematoma (cSDH). The aim of the present study was to quantify cerebral perfusion impairment in cSDH. Before surgery, 34 patients were examined neurologically using the National Institutes of Health Stroke Scale (NIHSS) score and investigated by CT perfusion imaging. Hematoma volume, localization, and hematoma configuration were recorded. Clinical and radiological data were correlated. Mean hematoma volume was 91.8?cm(3) (16.2-241.6?cm(3), standard deviation [SD] 49.5). Whole brain mean transit time (MTT) was slightly elevated (mean 36.6?sec, SD 5.8). Hematoma volume and cerebral blood volume (CBV) in the underlying hemisphere correlated marginally but not significantly (p=0.067). Perfusion parameters determined in the area below the hematoma (ABH) and the corresponding contralateral cortex (MAC) were highly significantly different regarding cerebral blood flow (CBF) (mean 88.8 vs. 70.4, p<0.01) and CBV (mean 29.4 vs. 22.5, p<0.01). On the other hand, MTT and Tmax were almost equal between these areas (MTT means 35.0 vs. 34.8, (p)=0.914; tMax means 16.0 vs. 15.4, p=0.587). We conclude that local brain perfusion autoregulation is active in the cortical area below cSDH. CBV and CBF are significantly upregulated in the cortical area below cSDH indicating the effect of autoregulation in tissue at risk of ischemia. Cerebral autoregulation is intact in cSDH. Neurologic deficits are likely induced by borderline perfusion. PMID:23227943

Slotty, Philipp Jörg; Kamp, Marcel Alexander; Steiger, Steiger Hans-Jakob; Cornelius, Jan Frederick; Macht, Stephan; Stummer, Walter; Turowski, Bernd

2013-02-11

387

Attenuation of hypoxic ventilation by hyperbaric O2: effects of pressure and exposure time.  

PubMed

Hyperoxia affects O2 chemoreception in the highly perfused carotid bodies and causes a reduction of the ventilatory hypoxic drive (HD) as was shown for anesthetized cats and awake rats. We looked for a quantitative description of such an effect on HD as a function of both O2 pressure and exposure duration. Ventilation of rats was measured using the barometric method before and after hyperbaric O2 (HBO) exposure, at either air, 80% O2, or 4% O2. We used three exposure durations: 180, 550 and 900 min. The O2 pressure ranged between 1.2 and 3.0 ATA. At each time duration we used four to five groups of rats at a range of O2 pressures that yielded the full scale of effect on HD but avoided obvious lasting difficulties in breathing. HBO caused a reduction of breathing frequency and elevation of tidal volume in both air and 80% O2 but almost no change in minute ventilation. Hypoxic minute ventilation (4% O2) decreased after HBO, mainly through reduced frequency. HD was described by a power function of O2 pressure for each HBO duration. HD did not decline below 20% of the full control response. Ventilatory HD diminution is pictured as a function of both O2 pressure and HBO duration. The dependency of HD on exposure time and on pressure is similar to other known toxic effects of HBO. PMID:2708214

Liberzon, I; Arieli, R; Kerem, D

1989-02-01

388

Catecholamine Release by Intracerebral Perfusion of 6-Hydroxydopamine and Desipramine.  

National Technical Information Service (NTIS)

The rate of catecholamine release was examined at perfusion sites in the diencephalon of the unanesthetized rat during the perfusion of a solution of 6-hydroxydopamine (6-OHDA) or desipramine (DMI). Endogenous stores of norepinephrine (NE) and dopamine (D...

G. E. Martin R. D. Myers D. C. Newberg

1975-01-01

389

Evaluation of Renal Function in Perfused Rabbit Kidneys.  

National Technical Information Service (NTIS)

Extractions of inulin and para-aminohippurate were measured in perfused rabbit kidneys. These tests, which can be performed with relative rapidity, give an indication of a functional state of perfused kidney. It is suggested that these procedures could be...

T. I. Malinin C. E. Hollerman

1971-01-01

390

Perfusion lung imaging in the adult respiratory distress syndrome  

SciTech Connect

In 29 perfusion lung scans (PLS) of 19 patients with ARDS, 20 of which were obtained within six days from the onset of respiratory symptoms, perfusion abnormalities were the rule. These included focal, nonsegmental defects, mostly peripheral and dorsal, and perfusion redistribution away from the dependent lung zones. PLS were scored for the presence and intensity of perfusion abnormalities and the scores of perfusion redistribution were validated against numerical indices of blood flow distribution per unit lung volume. PLS scores were correlated with arterial blood gas values, hemodynamic parameters, and chest radiographic scores of ARDS. Arterial oxygen tension correlated with the scores of both perfusion defects and redistribution. Perfusion defects correlated better with the radiographic score of ARDS, and perfusion redistribution with PAP and vascular resistance. ARDS patients exhibit peculiar patterns of PLS abnormalities not observed in other disorders. Thus, PLS may help considerably in the detection and evaluation of pulmonary vascular injury in ARDS.

Pistolesi, M.; Miniati, M.; Di Ricco, G.; Marini, C.; Giuntini, C.

1986-07-01

391

Secretion management in the mechanically ventilated patient.  

PubMed

Secretion management in the mechanically ventilated patient includes routine methods for maintaining mucociliary function, as well as techniques for secretion removal. Humidification, mobilization of the patient, and airway suctioning are all routine procedures for managing secretions in the ventilated patient. Early ambulation of the post-surgical patient and routine turning of the ventilated patient are common secretion-management techniques that have little supporting evidence of efficacy. Humidification is a standard of care and a requisite for secretion management. Both active and passive humidification can be used. The humidifier selected and the level of humidification required depend on the patient's condition and the expected duration of intubation. In patients with thick, copious secretions, heated humidification is superior to a heat and moisture exchanger. Airway suctioning is the most important secretion removal technique. Open-circuit and closed-circuit suctioning have similar efficacy. Instilling saline prior to suctioning, to thin the secretions or stimulate a cough, is not supported by the literature. Adequate humidification and as-needed suctioning are the foundation of secretion management in the mechanically ventilated patient. Intermittent therapy for secretion removal includes techniques either to simulate a cough, to mechanically loosen secretions, or both. Patient positioning for secretion drainage is also widely used. Percussion and postural drainage have been widely employed for mechanically ventilated patients but have not been shown to reduce ventilator-associated pneumonia or atelectasis. Manual hyperinflation and insufflation-exsufflation, which attempt to improve secretion removal by simulating a cough, have been described in mechanically ventilated patients, but neither has been studied sufficiently to support routine use. Continuous lateral rotation with a specialized bed reduces atelectasis in some patients, but has not been shown to improve secretion removal. Intrapulmonary percussive ventilation combines percussion with hyperinflation and a simulated cough, but the evidence for intrapulmonary percussive ventilation in mechanically ventilated patients is insufficient to support routine use. Secretion management in the mechanically ventilated patient consists of appropriate humidification and as-needed airway suctioning. Intermittent techniques may play a role when secretion retention persists despite adequate humidification and suctioning. The technique selected should remedy the suspected etiology of the secretion retention (eg, insufflation-exsufflation for impaired cough). Further research into secretion management in the mechanically ventilated patient is needed. PMID:17894902

Branson, Richard D

2007-10-01

392

Fuzzy dynamic output feedback control with adaptive rotor imbalance compensation for magnetic bearing systems.  

PubMed

This paper presents a dynamic output feedback control with adaptive rotor-imbalance compensation based on an analytical Takagi-Sugeno fuzzy model for complex nonlinear magnetic bearing systems with rotor eccentricity. The rotor mass-imbalance effect is considered with a linear in the parameter approximator. Through the robust analysis for disturbance rejection, the control law can be synthesized in terms of linear matrix inequalities. Based on the suggested fuzzy output feedback design, the controller may be much easier to implement than conventional nonlinear controllers. Simulation validations show that the proposed robust fuzzy control law can suppress the rotor imbalance-induced vibration and has excellent capability for high-speed tracking and levitation control. PMID:15462450

Huang, Shi-Jing; Lin, Lih-Chang

2004-08-01

393

Extracorporeal Perfusion for Acute Respiratory Failure. Membrane Lung Perfusion for Acute Respiratory Failure.  

National Technical Information Service (NTIS)

The overall long term extracorporeal perfusion (ECMO) therapy in the treatment of severe acute respiratory distress syndrome (ARDS). Efforts were directed at four components of the overall goal: (1) Which lung diseases improve during ECMO or control thera...

W. M. Zapol

1976-01-01

394

Spontaneous breathing with airway pressure release ventilation favors ventilation in dependent lung regions and counters cyclic alveolar collapse in oleic-acid-induced lung injury: a randomized controlled computed tomography trial  

PubMed Central

Introduction Experimental and clinical studies have shown a reduction in intrapulmonary shunt with spontaneous breathing during airway pressure release ventilation (APRV) in acute lung injury. This reduction was related to reduced atelectasis and increased aeration. We hypothesized that spontaneous breathing will result in better ventilation and aeration of dependent lung areas and in less cyclic collapse during the tidal breath. Methods In this randomized controlled experimental trial, 22 pigs with oleic-acid-induced lung injury were randomly assigned to receive APRV with or without spontaneous breathing at comparable airway pressures. Four hours after randomization, dynamic computed tomography scans of the lung were obtained in an apical slice and in a juxtadiaphragmatic transverse slice. Analyses of regional attenuation were performed separately in nondependent and dependent halves of the lungs on end-expiratory scans and end-inspiratory scans. Tidal changes were assessed as differences between inspiration and expiration of the mechanical breaths. Results Whereas no differences were observed in the apical slices, spontaneous breathing resulted in improved tidal ventilation of dependent lung regions (P < 0.05) and less cyclic collapse (P < 0.05) in the juxtadiaphragmatic slices. In addition, with spontaneous breathing, the end-expiratory aeration increased and nonaerated tissue decreased in dependent lung regions close to the diaphragm (P < 0.05 for the interaction ventilator mode and lung region). Conclusion Spontaneous breathing during APRV redistributes ventilation and aeration to dependent, usually well-perfused, lung regions close to the diaphragm, and may thereby contribute to improved arterial oxygenation. Spontaneous breathing also counters cyclic collapse, which is a risk factor for ventilation-associated lung injury.

Wrigge, Hermann; Zinserling, Jorg; Neumann, Peter; Muders, Thomas; Magnusson, Anders; Putensen, Christian; Hedenstierna, Goran

2005-01-01

395

Simulation on hot drug perfusion machine system  

Microsoft Academic Search

In the research of hot drug perfusion machine, temperature control is very important. Hot drugs acting on the lesion is a direct impact on the efficacy of the patience. So the application of Intelligent control which is called Fuzzy Adaptive PID is developed to dynamically adjust parameters according to the real-time information. The purpose is achieving a low over shoot,

Zhao Xinzhong; Wu Di

2010-01-01

396

Reduced frontotemporal perfusion in psychopathic personality  

Microsoft Academic Search

Several brain-imaging studies have found associations between aberrant functioning in the frontal and temporal lobes and violent offending. We have previously reported decreased frontotemporal perfusion unrelated to psychosis, substance abuse, or current medication in 21 violent offenders. In the present study, we compared the regional cerebral blood flow (rCBF) in a new group of 32 violent offenders to scores on

Henrik Soderstrom; Leif Hultin; Mats Tullberg; Carsten Wikkelso; Sven Ekholm; Anders Forsman

2002-01-01

397

Automated sonographic evaluation of testicular perfusion  

NASA Astrophysics Data System (ADS)

Contrast-enhanced ultrasound (US) imaging is potentially applicable to the investigation of vascular disorders of the testis. We investigated the ability of two automated computer algorithms to analyse contrast-enhanced pulse inversion US data in a rabbit model of unilateral testicular ischaemia and to correctly determine relative testicular perfusion: nonlinear curve fitting of the US backscatter intensity as a function of time; and spectral analysis of the intensity time trace. We compared (i) five metrics based on the algorithmic data to testicular perfusion ratios obtained with radiolabelled microspheres, a reference standard; (ii) qualitative assessment of the US images by two independent readers blinded to the side of the experimental and control testes to the radiolabelled microsphere perfusion ratios; and (iii) results of the algorithmically-derived metrics to the qualitative assessments of the two readers. For the curve fit method, the algorithmically-derived metrics agreed with the reference standard in 54% to 68% of all cases. For the spectral method, the results agreed in 70% of all cases. The two readers agreed with the reference standard in 40% and 35% of all cases, respectively. These results suggest that automated methods of analysis may provide useful information in the assessment of testicular perfusion.

Thierman, Jonathan S.; Clement, Gregory T.; Kalish, Leslie A.; O'Kane, Patrick L.; Frauscher, Ferdinand; Paltiel, Harriet J.

2006-07-01

398

Coupling between resting cerebral perfusion and EEG.  

PubMed

While several studies have investigated interactions between the electroencephalography (EEG) and functional magnetic resonance imaging BOLD signal fluctuations, less is known about the associations between EEG oscillations and baseline brain haemodynamics, and few studies have examined the link between EEG power outside the alpha band and baseline perfusion. Here we compare whole-brain arterial spin labelling perfusion MRI and EEG in a group of healthy adults (n = 16, ten females, median age: 27 years, range 21-48) during an eyes closed rest condition. Correlations emerged between perfusion and global average EEG power in low (delta: 2-4 Hz and theta: 4-7 Hz), middle (alpha: 8-13 Hz), and high (beta: 13-30 Hz and gamma: 30-45 Hz) frequency bands in both cortical and sub-cortical regions. The correlations were predominately positive in middle and high-frequency bands, and negative in delta. In addition, central alpha frequency positively correlated with perfusion in a network of brain regions associated with the modulation of attention and preparedness for external input, and central theta frequency correlated negatively with a widespread network of cortical regions. These results indicate that the coupling between average EEG power/frequency and local cerebral blood flow varies in a frequency specific manner. Our results are consistent with longstanding concepts that decreasing EEG frequencies which in general map onto decreasing levels of activation. PMID:23160910

O'Gorman, R L; Poil, S-S; Brandeis, D; Klaver, P; Bollmann, S; Ghisleni, C; Lüchinger, R; Martin, E; Shankaranarayanan, A; Alsop, D C; Michels, L

2012-11-18

399

Perfusion CT in Colorectal Cancer: Comparison of Perfusion Parameters with Tumor Grade and Microvessel Density  

PubMed Central

Objective The purpose of this study was to prospectively compare pre-operative computed tomography (CT) perfusion parameters with tumor grade from colorectal adenocarcinoma (CRC) and to correlate pre-operative CT perfusion parameters with microvessel density (MVD) to evaluate angiogenesis in CRC. Materials and Methods Pre-operative perfusion CTs were performed with a 64-channel multidetector row CT in 27 patients (17 women and 10 men; age range 32-82 years) who were diagnosed with CRC involving the sigmoid and rectum between August 2006 and November 2007. All patients underwent surgery without pre-operative chemotherapy or radiation therapy. Dynamic perfusion CTs were performed for 65 seconds after intravenous injection of contrast medium (100 mL, 300 mg of iodine per mL, 5 mL/sec). Before surgery, blood flow (BF), blood volume, mean transit time (MTT), and permeability-surface area product were measured in the tumor. After surgery, one gastrointestinal pathologist evaluated tumor grade and performed immunohistochemical staining using CD 34 to determine MVD in each tumor. The Kruskal-Wallis test was used to compare CT perfusion parameters with tumor grade, and Pearson's correlation analysis was used to correlate CT perfusion parameters with MVD. Results In 27 patients with CRC, tumor grading was as follows: well differentiated (n = 8); moderately differentiated (n = 15); and poorly differentiated (n = 4). BF was higher in moderately differentiated CRC than well differentiated and poorly differentiated CRCs (p = 0.14). MTT was shorter in moderately differentiated than well differentiated and poorly differentiated CRCs (p = 0.039). The MVD was greater in poorly differentiated than well differentiated and moderately differentiated CRCs (p = 0.034). There was no significant correlation between other perfusion parameters and tumor grade. There was no significant correlation between CT perfusion parameters and MVD. Conclusion BF and MTT measurement by perfusion CT is effective in predicting moderately differentiated CRCs. However, perfusion CT is limited in distinguishing well differentiated and poorly differentiated CRCs. Pre-operative perfusion CT does not reflect the MVD of CRCs.

Kim, Jin Woong; Chang, Nam Kyu; Heo, Suk Hee; Shin, Sang Soo; Lee, Jae Hyuk; Hur, Young Hoe; Kang, Heoung Keun

2012-01-01

400

The effect of ventilation on spontaneous heating of coal  

Microsoft Academic Search

Ventilation plays an important role in the spontaneous heating of coal in an underground coal mine. If the ventilation rate is too high, heat is carried away by convection. If the ventilation rate is too low, the reaction rate becomes oxygen-limited. The effect of ventilation on the spontaneous heating of coal was investigated in an isothermal oven in this study.

Liming Yuan; Alex C. Smith

401

Variability in mean duration of mechanical ventilation among community hospitals.  

PubMed

We explored intensive care units' mean ventilator-days per patient as a possible objective alternative to ventilator-associated pneumonia rates for assessing quality of care for ventilated patients. Mean ventilator-days per patient varied 4-fold within a network of community hospitals despite adjusting for multiple patient and hospital factors. Further assessment of this metric is warranted. PMID:22561723

Klompas, Michael; Kleinman, Ken P; Karcz, Anita

2012-04-24

402

Volume-limited and volume-targeted ventilation.  

PubMed

This article shows that volume-targeted ventilation is physiologically more logical than pressure-limited ventilation, and is associated with a reduced risk of pneumothorax, hypocarbia, duration of ventilation, death or bronchopulmonary dysplasia, and severe intraventricular hemorrhage. Therefore, it should now be adopted as the main mode for mechanical ventilation of preterm neonates. PMID:22954266

Morley, Colin J

2012-09-01

403

Natural ventilation for passive cooling: measurement of discharge coefficients  

Microsoft Academic Search

For the design of natural ventilation systems for passive cooling in buildings, engineers and architects are interested in the prediction of ventilation rates as a function of position and size of the ventilation openings. In common use, there are both simple and detailed (i.e., multizone) ventilation models which rely basically on the same Bernoulli algorithm to describe airflow through large

F. Flourentzou; J. Van der Maas; C.-A. Roulet

1998-01-01

404

Non-Stationary Ventilation Conditions with Open Mine Fires.  

National Technical Information Service (NTIS)

Open mine fires lead to the occurrence, in non-horizontal ventilation roads, of a driving effect, which for ascensional ventilation leads to an increase, and for descensional ventilation to a decrease, in the amount of ventilation. From this it follows th...

W. Trutwin

1977-01-01

405

[Intrapleural perfusion hyperthermo-chemotherapy with cisplatin in patients with malignant pleural mesothelioma].  

PubMed

The preferred treatment for patients with malignant pleural mesothelioma (MPM) has not been determined. In order to obtain adequate control of malignant effusion for multimodality therapy, we have introduced intrapleural perfusion hyperthermo-chemotherapy (IPHC) with cisplatin. IPHC was performed with a roller pump and heat exchanger. Cisplatin was added when the temperature stabilized to a mean of 42.5 degrees C. Dosages of cisplatin were 80 mg/m2. The circuit was filled with 2,000 ml saline. A IPHC was performed for 60 minutes under both lung ventilation. IPHC with cisplatin is feasible, easy to perform, and relatively safe. This method had brought an ideal pleural adhesion. IPHC may offer excellent local control for patients with MPM. Some literatures have reported the utility of IPHC for trimodality therapy on MPM. PMID:19999570

Sakaguchi, Hirozo; Kaneko, Koichi

2009-11-01

406

Analysis of trials comparing High Frequency Ventilation with Conventional Mechanical Ventilation : Clinical Epidemiology in Intensive Care  

Microsoft Academic Search

An abundance of experimental and clinical evidence indicates that mechanical ventilation can cause ventilator induced lung damage (VILI). Primary mechanisms leading to VILI are volutrauma, i.e. use of large tidal volumes resulting in over-distension, and atelectotrauma, i.e. repetitive closing and opening of alveoli, causing shear stress. Ideally, mechanical ventilation should supply enough airway pressure, even in the end-expiratory phase of

C. W. Bollen

2006-01-01

407

Carbon dioxide mandatory ventilation (CO2MV): A new method for weaning from mechanical ventilation  

Microsoft Academic Search

Summary  We describe a new technique specially designed for weaning from mechanical ventilation: carbon dioxide mandatory ventilation\\u000a (CO2MV). CO2MV is based on feedback between end tidal expired partial pressure of carbon dioxide and ventilatory mode, controlled\\u000a or spontaneous. In order to evaluate its real interest we performed a randomized prospective study, CO2MV vs Intermittent\\u000a Mandatory Ventilation (IMV) and T. Tube Method

C. Chopin; M. C. Chambrin; J. Mangalaboyi; P. Lestavel; F. Fourrier

1989-01-01

408

Comment on "Ocean heat content and Earth?s radiation imbalance. II. Relation to climate shifts"  

NASA Astrophysics Data System (ADS)

A recent paper by Douglass and Knox (hereafter DK12) states that the global flux imbalance between 2002 and 2008 was approximately -0.03±0.06 W/m, from which they concluded the CO2 forcing feedback is negative. However, DK12 only consider the ocean heat content (OHC) increase from 0 to 700 meters, neglecting the OHC increase at greater depths. Here we include OHC data to a depth of 2000 meters and demonstrate this data explains the majority of the discrepancies between DK12 and previous works, and that the current global flux imbalance is consistent with continued anthropogenic climate change.

Nuccitelli, Dana; Way, Robert; Painting, Rob; Church, John; Cook, John

2012-10-01

409

Automatic IQ Imbalance Compensation Technique for Quadrature Modulator by Single-Tone Testing  

NASA Astrophysics Data System (ADS)

This letter proposes an automatic IQ imbalance compensation technique for quadrature modulators by means of spectrum measurement of RF signal using a spectrum analyzer. The analyzer feeds back only magnitude information of the frequency spectrum of the signal. To realize IQ imbalance compensation, the conventional method of steepest descent is modified; the descent direction is empirically determined and a variable step-size is introduced for accelerating convergence. The experimental results for a four-channel transmitter operating at 11GHz are presented for verification.

Kim, Minseok; Konishi, Yohei; Takada, Jun-Ichi; Gao, Boxin

410

Linear Receiver for OFDMA Uplink with both CFOs and IQ Imbalances  

NASA Astrophysics Data System (ADS)

In orthogonal frequency division multiple access (OFD-MA) uplink, the distortions introduced by both multiple carrier frequency offsets (CFOs) and in-phase and quadrature-phase (IQ) imbalances will severely degrade the system performance. With both CFOs and IQ imbalances, signal detection at the receiver becomes hard, if not impossible. In this letter, a linear receiver is proposed to cope with the distortions at a slight drop in system transmission rate. The analysis and simulations demonstrate the effectiveness of the proposed approach.

Zhang, Weile; Yin, Qinye

411

[Alprazolam for patients with psychotic symptoms or autonomic imbalance symptoms after breast cancer surgery].  

PubMed

Effectiveness of alprazolam in daily dosages of 0.8-1.2 mg was studied in 28 patients who showed psychotic symptoms or autonomic imbalance symptoms after operation for breast cancer. Psychotic symptoms included depression, anxiety, tension, and restlessness, and symptoms of autonomic imbalance included sleep disorder, anorexia, and pains. All of these symptoms were improved at high ratios by alprazolam. The drug was very useful in 16 cases (57.1%), useful in 11 cases (39.3%), and slightly useful in one case (3.6%). The only adverse reaction reported was unsteady gait in one case. PMID:2069404

Tamaki, K; Nishida, M; Hiraide, H; Tamakuma, S

1991-07-01

412

Automatic and visual reproducibility of perfusion and function measures for myocardial perfusion SPECT  

PubMed Central

Background We define the repeatability coefficients (RC) of key quantitative and visual perfusion and function parameters that can be derived by the QGS/QPS automated software and by expert visual observer from gated myocardial perfusion SPECT (MPS) scans. Methods Standard QGS/QPS algorithms have been applied to derive quantitative perfusion and function parameters in 200 99mTc-tetrofosmin rest/stress MPS scans, obtained in 100 consecutive patients who underwent 2 separate gated rest/stress scans on the same camera. Variables included stress, rest, and ischemic total perfusion deficit (TPD), ejection fraction, motion, and thickening. Visual perfusion/motion scores were derived by an expert reader using randomized scan order and normalized to % myocardium. Results Quantitative and visual parameters were highly reproducible with smaller RC for some quantitative measures as compared to visual measures (P < .0001). RC for quantitative measures were 3.3% for stress TPD, 1.8% for rest TPD, and 3.2% for ischemic TPD and for visual scoring 4.8% for stress, 3.8% for rest, and 4.3% for ischemic (P ? .002). The results in each vessel territory showed that in the right coronary artery (RCA) territory the quantitative approach had improved reproducibility as compared to visual reading. Visual thickening scoring was more reproducible than motion scoring (P < .0001). Conclusions This study demonstrates that standard perfusion and function parameters derived from MPS by visual or quantitative analysis are highly reproducible with some advantages to the quantitative approach.

Xu, Yuan; Hayes, Sean; Ali, Iftikhar; Ruddy, Terrence D.; Wells, R. Glenn; Berman, Daniel S.; Germano, Guido

2010-01-01

413

Correlation of Early Dynamic CT Perfusion Imaging with Whole-Brain MR Diffusion and Perfusion Imaging in Acute Hemispheric Stroke  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Compared with MR imaging, dynamic CT perfusion imag- ing covers only a fraction of the whole brain. An important assumption is that CT perfusion abnormalities correlate with total ischemic volume. The purpose of our study was to measure the degree of correlation between abnormalities seen on CT perfusion scans and the volumes of abnormality seen on MR

James D. Eastwood; Michael H. Lev; Max Wintermark; Clemens Fitzek; Daniel P. Barboriak; David M. Delong; Ting-Yim Lee; Tarek Azhari; Michael Herzau; Vani R. Chilukuri; James M. Provenzale

414

21 CFR 868.5895 - Continuous ventilator.  

Code of Federal Regulations, 2013 CFR

...Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5895 Continuous ventilator. (a) Identification. A continuous...

2013-04-01

415

Monitoring ventilator weaning--predictors of success.  

PubMed

Improving the prediction of successful ventilator weaning and extubation is a goal that all Intensivists and perioperative physicians strive for. The successful wean and extubation of ventilated patients decreases hospital length of stay and associated costs, but more importantly it also reduces patient morbidity and mortality. This review evaluates traditional and novel indices used in the assessment for ventilatory wean readiness. Novel equipment such as the Bicore pulmonary monitor and the CO2 SMO Plus are now available on the market to assess and monitor ventilator weaning and may offer some value in this process. We also review the non-respiratory factors affecting weaning and the role of the bedside nurse and respiratory therapist. Resolution of the pulmonary compromise and an understanding of respiratory physiology, used in conjunction with monitored indices of weaning parameters in a consistent fashion will continue to improve our success rates of ventilator weaning and extubation. PMID:12580224

Weavind, L; Shaw, A D; Feeley, T W

2000-01-01

416

46 CFR 98.25-75 - Ventilation.  

Code of Federal Regulations, 2012 CFR

...MISCELLANEOUS VESSELS SPECIAL CONSTRUCTION, ARRANGEMENT, AND OTHER PROVISIONS FOR CERTAIN DANGEROUS CARGOES IN BULK Anhydrous Ammonia in Bulk § 98.25-75 Ventilation. (a) All enclosed spaces containing cargo tanks fitted with bottom...

2012-10-01

417

46 CFR 111.105-21 - Ventilation.  

Code of Federal Regulations, 2012 CFR

...105-21 Section 111.105-21 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Hazardous Locations § 111.105-21 Ventilation. A...

2012-10-01

418

Eustachian tube function after transmyringeal ventilation.  

PubMed

This study anus at determining the effect of transmyringeal ventilation on Eustachian tube functions. Seventy ears clinically diagnosed as having otitis media with effusion or grade I and II retraction of pars-tensa of tympanic membrane were treated with antiallergics, decongestants, mucolytics, and antibiotics as required for maximum upto three months. In forty-five ears that showed neither symptomatic nor audiometric improvement, transmyringeal ventilation was restored by myringotomy and ventilation tube insertion. There after, Eustachian tube functions were assessed by using pressure equilibration test. The post-operative audiograms showed mean hearing gain of 16. 6 dB (S D±7.9) in majority (96%) of the ears. At first week 93% ears could not either totally or partially equilibrate positive or negative pressure. The percentage in the poor function group remained 91% even at the end of 6 months showing no significant effect of ventilation tube insertion on active ET functions. PMID:23120122

Gupta, S C; Malhotra, M; Singh, M

2005-01-01

419

30 CFR 75.333 - Ventilation controls.  

Code of Federal Regulations, 2013 CFR

...HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.333...Conducting Strength Tests of Panels for Building Constructionâ (Section 12âTransverse...Conducting Strength Tests of Panels for Building Constructionâ is incorporated...

2013-07-01

420

Waste tank ventilation system waste material accumulations  

SciTech Connect

This paper calculates the amount of material that accumulates in the ventilation systems of various Tank Waste Remediation System facilities and estimates the amount of material that could be released due to a rapid pressurization.

Van Vleet, R.J., Westinghouse Hanford

1996-08-06

421

Demand Controlled Ventilating Systems: Sensor Tests.  

National Technical Information Service (NTIS)

A test program has been designed to evaluate the performance characteristics of sensors for the automatic control of ventilation rates. The test program consists of two main parts, one being the evaluation of sensor performance in laboratory tests and the...

P. Fahlen H. Andersson S. Ruud

1992-01-01

422

24 CFR 3285.505 - Crawlspace ventilation.  

Code of Federal Regulations, 2013 CFR

...the entry of rodents. In areas subject to freezing, the coverings for the ventilation openings...the skirting to the outside. Any surface water runoff from the furnace, air conditioning, or water heater drains must be directed away...

2013-04-01

423

EVALUATION OF VENTILATION PERFORMANCE FOR INDOOR SPACE  

EPA Science Inventory

The paper discusses a personal-computer-based application of computational fluid dynamics that can be used to determine the turbulent flow field and time-dependent/steady-state contaminant concentration distributions within isothermal indoor space. (NOTE: Ventilation performance ...

424

Humidification of inspired gases during mechanical ventilation.  

PubMed

Humidification of inspired gas is mandatory for all mechanically ventilated patients to prevent secretion retention, tracheal tube blockage and adverse changes occurring to the respiratory tract epithelium. However, the debate over "ideal" humidification continues. Several devices are available that include active and passive heat and moisture exchangers and hot water humidifiers Each have their advantages and disadvantages in mechanically ventilated patients. This review explores each device in turn and defines their role in clinical practice. PMID:22269929

Gross, J L; Park, G R

2012-01-23

425

Sensor-based demand controlled ventilation  

SciTech Connect

In most buildings, occupancy and indoor pollutant emission rates vary with time. With sensor-based demand-controlled ventilation (SBDCV), the rate of ventilation (i.e., rate of outside air supply) also varies with time to compensate for the changes in pollutant generation. In other words, SBDCV involves the application of sensing, feedback and control to modulate ventilation. Compared to ventilation without feedback, SBDCV offers two potential advantages: (1) better control of indoor pollutant concentrations; and (2) lower energy use and peak energy demand. SBDCV has the potential to improve indoor air quality by increasing the rate of ventilation when indoor pollutant generation rates are high and occupants are present. SBDCV can also save energy by decreasing the rate of ventilation when indoor pollutant generation rates are low or occupants are absent. After providing background information on indoor air quality and ventilation, this report provides a relatively comprehensive discussion of SBDCV. Topics covered in the report include basic principles of SBDCV, sensor technologies, technologies for controlling air flow rates, case studies of SBDCV, application of SBDCV to laboratory buildings, and research needs. SBDCV appears to be an increasingly attractive technology option. Based on the review of literature and theoretical considerations, the application of SBDCV has the potential to be cost-effective in applications with the following characteristics: (a) a single or small number of dominant pollutants, so that ventilation sufficient to control the concentration of the dominant pollutants provides effective control of all other pollutants; (b) large buildings or rooms with unpredictable temporally variable occupancy or pollutant emission; and (c) climates with high heating or cooling loads or locations with expensive energy.

De Almeida, A.T. [Universidade de Coimbra (Portugal). Dep. Eng. Electrotecnica; Fisk, W.J. [Lawrence Berkeley National Lab., CA (United States)

1997-07-01

426

Continuous epidural infusion for postoperative mechanical ventilation  

Microsoft Academic Search

We evaluated in analgesic and sedative effects of continuous epidural infusion of two analgesic regimens in ventilated patients\\u000a following esophagectomy. Fortysix patients, divided into two treatment groups, received postoperative continuous epidural\\u000a infusion of morphine, or that of a combination of bupivacaine and morphine. Assessments were made with the following indices:\\u000a pain relief score, somnolence score, patient ventilator coordination score, and

Shinichi Sakura; Mariko Sumi; Yoji Saito; Jyunken Koh; Makoto Asano; Akio Tanaka; Yoshihiro Kosaka

1990-01-01

427

Shut-off mechanism for ventilation hose  

DOEpatents

A shut-off mechanism to provide automatic closure of a ventilation hose when the operation of drawing air through the hose is terminated. The mechanism includes a tube of light gauge metal inside of which are mounted a plurality of louver doors positioned in the closed position due to gravity when the ventilation unit is not operational. When the unit is operational, air flowing into the unit maintains the doors in the open position. 5 figs.

Huyett, J.D.; Meskanick, G.R.

1989-12-07

428

Analytic Reviews: High-Frequency Oscillatory Ventilation (HFOV) and Airway Pressure Release Ventilation (APRV): A Practical Guide  

Microsoft Academic Search

Despite advances in ventilator management, 31% to 38% of patients with adult respiratory distress syndrome (ARDS) will die, some from progressive respiratory failure. Inability to adequately oxygenate patients with severe ARDS has prompted extensive efforts to identify what are now known as alternative modes of ventilation including high-frequency oscillatory ventilation and airway pressure release ventilation. Both modalities are based on

S. P. Stawicki; Munish Goyal; Babak Sarani

2009-01-01

429

Noninvasive Assisted Pressure-Controlled Ventilation: As Effective as Pressure Support Ventilation in Chronic Obstructive Pulmonary Disease?  

Microsoft Academic Search

Background: Noninvasive ventilation (NIV) is being increasingly used in hypercapnic chronic obstructive pulmonary disease (COPD) patients but the most appropriate ventilation mode is still not known. Objectives: The aim of this study was to investigate if assisted pressure-controlled ventilation (APCV) can be a better alternative to pressure-support ventilation (PSV) for NIV in COPD patients with acute hypercapnic respiratory failure (AHRF).

Cenk Kirakli; Tutku Cerci; Zeynep Zeren Ucar; Onur Fevzi Erer; Hakan Alp Bodur; Semra Bilaceroglu; Serir Aktogu Ozkan

2008-01-01

430

Ventilation criteria for IDMS facility  

SciTech Connect

Both Facility Evaluation Board (FEB) reviews of the Integrated DWPF Melter System (IDMS) have identified the inconsistency of the current IDMS Process Hazards Review (PHR) versus actual IDMS practice as regards the criteria to contain air borne pollutants that may be present in the Process Room (e.g. benzene and mercury). The PHR states that a 1.0 in. wc pressure differential be maintained between the IDMS Process Room and Building 672-T. In addition, the PHR further specifies that the linear velocity through openings into the Process Room (e.g. open doors) be equal to or greater than 150 fpm. Finally, the PHR recommended that mercury vapor and benzene monitors be installed in the Process Room ventilation exhaust to alert personnel to the presence of vapors of benzene and/or mercury before entering the Process Room. This report summarizes the results of reassessment of these criteria and the specific recommendation for permanent installation of mercury and benzene vapor monitors in the vapor exhaust of the Process Room.

Lambert, D.P.

1996-07-03

431

Transpleural ventilation of explanted human lungs  

PubMed Central

Background The hypothesis that ventilation of emphysematous lungs would be enhanced by communication with the parenchyma through holes in the pleural surface was tested. Methods Fresh human lungs were obtained from patients with emphysema undergoing lung transplantation. Control human lungs were obtained from organ donors whose lungs, for technical reasons, were not considered suitable for implantation. Lungs were ventilated through the bronchial tree or transpleurally via a small hole communicating with the underlying parenchyma over which a flanged silicone tube had been cemented to the surface of the lung (spiracle). Measurements included flow?volume?time curves during passive deflation via each pathway; volume of trapped gas recovered from lungs via spiracles when no additional gas was obtainable passively from the airways; and magnetic resonance imaging assessment of spatial distribution of hyperpolarised helium (3He) administered through either the airways or spiracles. Results In emphysematous lungs, passively expelled volumes at 20?s were 94% greater through spiracles than via the airways. Following passive deflation from the airways, an average of 1.07?litres of trapped gas volume was recoverable via spiracles. Regions were ventilated by spiracles that were less well ventilated via bronchi. Conclusions Because of the extensive collateral ventilation present in emphysematous lungs, direct communication with the lung parenchyma through non?anatomical pathways has the potential to improve the mechanics of breathing and hence ventilation.

Choong, Cliff K; Macklem, Peter T; Pierce, John A; Lefrak, Stephen S; Woods, Jason C; Conradi, Mark S; Yablonskiy, Dimitry A; Hogg, James C; Chino, Kimiaki; Cooper, Joel D

2007-01-01

432

Active Ventilation Report RCDP Cycle II.  

SciTech Connect

This report documents the analysis of the performance of natural and mechanical ventilation in Pacific Northwest homes. The analysis was part of Cycle 2 of the Residential Construction Demonstration Project, sponsored by Bonneville Power Administration (BPA). Since 1986, the Residential Construction Demonstration Project (RCDP) has sponsored the collection of data on energy efficient homes in the Pacific Northwest that comply with these new standards and requirements. Cycle 2 of RCDP was conducted between September 1987 and April 1990. It concentrated on energy innovations in homes built to the Super Good Cents specifications. All of the test homes have electric heat and mechanical ventilation systems. Seven different types of active ventilation systems are represented in the homes. Three of these system types are equipped with heat recovery devices, and are represented in approximately a quarter of the test homes. The potential for both natural and mechanical ventilation was measured. Potential structural leakage was measured by blower door testing. Flow rate and operating time of mechanical ventilation systems were measured with flow hoods and hour meters. Actual ventilation was measured by using a passive tracer gas technique for several weeks during the heating season and at times of normal occupancy. 3 refs., 12 figs., 4 tabs.

Douglass, John G., Palmiter, Larry S., Brown, Ian, Bond, Tami, Washington State Energy Office

1991-02-01

433

Injurious mechanical ventilation affects neuronal activation in ventilated rats  

PubMed Central

Introduction Survivors of critical illness often have significant long-term brain dysfunction, and routine clinical procedures like mechanical ventilation (MV) may affect long-term brain outcome. We aimed to investigate the effect of the increase of tidal volume (Vt) on brain activation in a rat model. Methods Male Sprague Dawley rats were randomized to three groups: 1) Basal: anesthetized unventilated animals, 2) low Vt (LVt): MV for three hours with Vt 8 ml/kg and zero positive end-expiratory pressure (ZEEP), and 3) high Vt (HVt) MV for three hours with Vt 30 ml/kg and ZEEP. We measured lung mechanics, mean arterial pressure (MAP), arterial blood gases, and plasma and lung levels of cytokines. We used immunohistochemistry to examine c-fos as a marker of neuronal activation. An additional group of spontaneously breathing rats was added to discriminate the effect of surgical procedure and anesthesia in the brain. Results After three hours on LVt, PaO2 decreased and PaCO2 increased significantly. MAP and compliance remained stable in MV groups. Systemic and pulmonary inflammation was higher in MV rats than in unventilated rats. Plasma TNF? was significantly higher in HVt than in LVt. Immunopositive cells to c-fos in the retrosplenial cortex and thalamus increased significantly in HVt rats but not in LVt or unventilated rats. Conclusions MV promoted brain activation. The intensity of the response was higher in HVt animals, suggesting an iatrogenic effect of MV on the brain. These findings suggest that this novel cross-talking mechanism between the lung and the brain should be explored in patients undergoing MV.

2011-01-01

434

Dependence of ventilation image derived from 4D CT on deformable image registration and ventilation algorithms.  

PubMed

Ventilation imaging using 4D CT is a convenient and low-cost functional imaging methodology which might be of value in radiotherapy treatment planning to spare functional lung volumes. Deformable image registration (DIR) is needed to calculate ventilation imaging from 4D CT. This study investigates the dependence of calculated ventilation on DIR methods and ventilation algorithms. DIR of the normal end expiration and normal end inspiration phases of the 4D CT images was used to correlate the voxels between the two respiratory phases. Three different DIR algorithms, optical flow (OF), diffeomorphic demons (DD), and diffeomorphic morphons (DM) were retrospectively applied to ten esophagus and ten lung cancer cases with 4D CT image sets that encompassed the entire lung volume. The three ventilation extraction methods were used based on either the Jacobian, the change in volume of the voxel, or directly calculated from Hounsfield units. The ventilation calculation algorithms used are the Jacobian, ?V, and HU method. They were compared using the Dice similarity coefficient (DSC) index and Bland-Altman plots. Dependence of ventilation images on the DIR was greater for the ?V and the Jacobian methods than for the HU method. The DSC index for 20% of low-ventilation volume for ?V was 0.33 ± 0.03 (1 SD) between OF and DM, 0.44 ± 0.05 between OF and DD, and 0.51 ± 0.04 between DM and DD. The similarity comparisons for Jacobian were 0.32 ± 0.03, 0.44 ± 0.05, and 0.51 ± 0.04, respectively, and for HU they were 0.53 ± 0.03, 0.56 ± 0.03, and 0.76 ± 0.04, respectively. Dependence of extracted ventilation on the ventilation algorithm used showed good agreement between the ?V and Jacobian methods, but differed significantly for the HU method. DSC index for using OF as DIR was 0.86 ± 0.01 between ?V and Jacobian, 0.28 ± 0.04 between ?V and HU, and 0.28 ± 0.04 between Jacobian and HU, respectively. When using DM or DD as DIR, similar values were obtained when comparing the different ventilation calculation methods. The similarity values for the 20% high-ventilation volume were close to those found for the 20% low-ventilation volume. The results obtained with DSC index were confirmed when using the Bland-Altman plots for comparing the ventilation images. Our data suggest that ventilation calculated from 4D CT depends on the DIR algorithm employed. Similarities between ?V and Jacobian are higher than between ?V and HU, and Jacobian and HU. PMID:23835389

Latifi, Kujtim; Forster, Kenneth M; Hoffe, Sarah E; Dilling, Thomas J; van Elmpt, Wouter; Dekker, Andre; Zhang, Geoffrey G

2013-07-08

435

Circulatory and respiratory effects evoked by hypertonic ventriculo-cisternal perfusion.  

PubMed

The cerebral ventricular system of anesthetized dogs was perfused with synthetic isotonic CSF and, for 80 s intervals, with hypertonic CSF of various compositions. Hypertonic perfusion evoked centrally mediated marked increases in arterial blood pressure, heart rate, respiratory rate, and ventilation and, after some delay, an excitatory reaction resembling arousal. The responses were coordinated in time with the induced CSF hypertonicity, graded in relation to its magnitude, and reversible on return to isotonicity. The effects, which seemed to be elicited from periventricular structures in the brain stem, were more pronounced and consistent when CSF hypertonicity was produced by adding NaCl or Na-lactate than monosacharides to the isotonic CSF solution. Analysis of the cardiobascular responses indicated that they were caused by increased sympathetic vasoconstrictor and cardiac accelerance fibre activity and by inhibition of vagal discharge to the heart. The described pattern of response much resembles that evoked by physical exercise, a state which might lead to osmolar changes in the brain and CSF of a similar kind to that in the present study as a consequence of the pronounced work-induced arterial hyperosmolality. It is suggested that such an osmotic mechanism might constitute a "metabolic link" in the centrally mediated circulatory and respiratory adjustments in exercise. PMID:1174005

Mellander, S; Hillman, J

1975-06-01

436

Mechanical ventilation reduces rat diaphragm blood flow and impairs O2 delivery and uptake  

PubMed Central

Objectives Although mechanical ventilation (MV) is a life-saving intervention in patients suffe