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Results 201 - 250 of 1442
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Proquitté Hans - - 2006
OBJECTIVE: Heptafluoropropane is an inert gas commercially used as propellant for inhalers. Since heptafluoropropane can be detected in low concentrations, it could also be used as a tracer gas to measure functional residual capacity and ventilation homogeneity. The aim of the present study was to validate functional residual capacity measurements ...
Dohna-Schwake Christian - - 2006
In neuromuscular disorders, reduced peak cough flows (PCFs) are considered to increase the risk of respiratory complications such as pneumonia or chronic atelectasis. Different methods were described to improve PCF. However, these studies were primarily carried out in adults, and there is limited information regarding the use and efficacy of ...
Seccombe Leigh M - - 2006
One technique employed by competitive breath-hold divers to increase diving depth is to hyperinflate the lungs with glossopharyngeal breathing (GPB). Our aim was to assess the relationship between measured volume and pressure changes due to GPB. Seven healthy male breath-hold divers, age 33 (8) [mean (SD)] years were recruited. Subjects ...
Lechtzin Noah - - 2006
RATIONALE: Lung compliance has been found to be low in patients with chronic diaphragmatic weakness or paralysis but has not been well-studied in patients with amyotrophic lateral sclerosis (ALS). Noninvasive positive-pressure ventilation (NPPV) prolongs survival in ALS patients but may also have additional beneficial effects. OBJECTIVES: This study evaluated static ...
Gross Roxann Diez - - 2006
OBJECTIVE: The subglottic pressure theory for swallowing asserts that laryngeal mechanoreceptors have a role in the regulation of swallowing function. The primary purpose of this study was to determine if subglottic air pressure is generated during swallowing in a healthy, nontracheostomized person. METHODS: This pilot investigation used a prospective, repeated-measures ...
Talmor Daniel D Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA, - - 2006
Pressure inflating the lung during mechanical ventilation is the difference between pressure applied at the airway opening (Pao) and pleural pressure (Ppl). Depending on the chest wall's contribution to respiratory mechanics, a given positive end-expiratory and/or end-inspiratory plateau pressure may be appropriate for one patient but inadequate or potentially injurious ...
Mentzelopoulos S D - - 2006
Based on prior data, the current authors hypothesised that beneficial pronation effects on gas exchange and respiratory mechanics might be maximised in severely hyperinflated chronic bronchitis patients. The current authors also sought to elucidate underlying mechanisms and to determine whether pronation effects are reflected by postural changes in inspiratory pressure-volume ...
Ferguson Gary T - - 2006
Patients with chronic obstructive pulmonary disease (COPD) often have some degree of hyperinflation of the lungs. Hyperinflated lungs can produce significant detrimental effects on breathing, as highlighted by improvements in patient symptoms after lung volume reduction surgery. Measures of lung volumes correlate better with impairment of patient functional capabilities than ...
Izumizaki Masahiko - - 2006
Thixotropy conditioning of inspiratory muscles consisting of maximal inspiratory effort performed at an inflated lung volume is followed by an increase in end-expiratory position of the rib cage in normal human subjects. When performed at a deflated lung volume, conditioning is followed by a reduction in end-expiratory position. The present ...
Overgaard Kristian - - 2006
Breath-hold divers train and compete in maximal apnea performance. Glossopharyngeal inhalation (GI) is commonly used to increase lung volume above vital capacity (VC) prior to apnea. We investigated the hypothesis that this practice would increase apnea performance and relaxed airway pressure. Seven well-trained breath-hold divers performed maximal bouts of apnea ...
Hinz J - - 2006
BACKGROUND: We hypothesized, that in mechanically ventilated patients with acute respiratory failure, regional pressure volume curves differ markedly from conventional global pressure volume curves of the whole lung. METHODS: In nine mechanically ventilated patients with acute respiratory failure during an inspiratory low-flow manoeuvre, conventional global pressure volume curves were registered ...
Jansson Anne-Helene - - 2006
Emphysema, a leading cause of respiratory disability and mortality in humans, is characterized by destruction of alveolar walls and enlargement of airspaces. Animal studies are critical in understanding the pathogenesis of emphysema. However, current measurements of airspace enlargement and emphysema in small laboratory animals are labor intensive and may not ...
Donaldson Scott H - - 2006
BACKGROUND: Abnormal homeostasis of the volume of airway surface liquid in patients with cystic fibrosis is thought to produce defects in mucus clearance and airway defense. Through osmotic forces, hypertonic saline may increase the volume of airway surface liquid, restore mucus clearance, and improve lung function. METHODS: A total of ...
Lenz, Tanja I
Pressure–volume (P–V) curves for leaves or terminal shoots summarize leaf-level responses to increasing water deficit. P–V curve traits and field-measured shoot xylem pressures were characterized across 62 species from four sites differing in rainfall and soil phosphorus. Within-species variation in the measured traits was small relative to differences among species ...
Brochard Laurent - - 2006
The pressure-volume (PV) curve is a physiological tool proposed for diagnostic or monitoring purposes during mechanical ventilation of acute respiratory distress syndrome. The reduction in compliance measured by the PV curve and the different inflection points on the curve are considered interesting markers of the severity of and the levels ...
Schmidt Eric P - - 2006
The rapidity of progression of amyotrophic lateral sclerosis (ALS) to death or respiratory failure impacts patients, clinicians, and clinical investigators. This study compared the abilities of various pulmonary function tests to predict tracheostomy-free survival. We evaluated 95 ALS patients by determining upright and supine forced vital capacity (FVC), maximal inspiratory ...
Zulli Roberto - - 2006
OBJECTIVE: Chronic obstructive pulmonary disease (COPD) is a highly prevalent syndrome, deeply affecting the cardiovascular system as well as the lungs. We investigated the prognostic role of the QT interval and QT dispersion (QTD) in predicting all-cause, respiratory and cardiovascular mortality in COPD, and the relationship between these electrocardiographic parameters ...
Chetta Alfredo - - 2006
A relevant ventilatory defect occurs after sternotomy, a very common thoracic surgical opening. The mechanism of the ventilatory impairment is unclear. Moreover, until now, the effect of sternotomy on pulmonary gas exchange has scarcely been investigated. We evaluated the time-course up to recovery and changes in spirometry, maximum static inspiratory ...
Lausted Christopher G - - 2006
Maximum pressures developed by the respiratory muscles can indicate the health of the respiratory system, help to determine maximum respiratory flow rates, and contribute to respiratory power development. Past measurements of maximum pressures have been found to be inadequate for inclusion in some exercise models involving respiration. Maximum inspiratory and ...
McCarren Bredge B Faculty of Health Sciences, The University of Sydney, Lidcombe, NSW 1825, Australia. - - 2006
What is the relationship between vibration of the chest wall and the resulting chest wall force, chest wall circumference,intrapleural pressure, and expiratory flow rate? Is the change in intrapleural pressure during vibration the sum of the intrapleural pressure due to recoil of the lung, chest wall compression, and chest wall ...
Souza-Fernandes Alba B - - 2006
The pathophysiology of systemic lupus erythematosus (SLE) has been very well described in many organs. However, the relation between extracellular matrix changes and lung dynamic mechanical behaviour deserves elucidation. To that end, pulmonary mechanics, lung morphometry and the amount of collagen and elastic fibres in the alveolar septa were analysed ...
Washko George R - - 2006
Ventilator management decisions in acute lung injury could be better informed with knowledge of the patient's transpulmonary pressure, which can be estimated using measurements of esophageal pressure. Esophageal manometry is seldom used for this, however, in part because of a presumed postural artifact in the supine position. Here, we characterize ...
Komori Eisaku - - 2005
Flow limitation during pressure-driven expiration in liquid-filled lungs was examined in intact, euthanized New Zealand white rabbits. The aim of this study was to further characterize expiratory flow limitation during gravitational drainage of perfluorocarbon liquids from the lungs, and to study the effect of perfluorocarbon type and negative mouth pressure ...
Mentzelopoulos Spyros D - - 2005
OBJECTIVE: In acute respiratory distress syndrome the body posture effects on pressure-volume (PV) curves are still unclear. We examined the effects of prone position on inflation PV curves and their potential relationships with postural alterations in gas exchange. DESIGN AND SETTING: Prospective study with patients serving as their own controls ...
Stevenson Nicola J - - 2005
RATIONALE: Exacerbation of chronic obstructive pulmonary disease commonly causes hospitalization. The change in lung mechanics during exacerbation and its relationship to symptoms in spontaneously breathing individuals has not been described. OBJECTIVE: We hypothesized that changes in both airflow and lung volumes would occur during an exacerbation, but that only volume ...
Hamnegård Carl Hugo - - 2006
Preoperative prediction of a successful outcome following lung volume reduction surgery (LVRS) for emphysema is imperfect. One mechanism could be improvement in respiratory muscle function yet controversy exists regarding the magnitude and mechanism of such an improvement. Therefore, we measured diaphragm strength in 18 patients before and after LVRS. Mean ...
Ingenito Edward P - - 2005
BACKGROUND: Bronchoscopic methods for achieving lung volume reduction (BLVR) are presently undergoing clinical trials, and will soon be clinically available. Understanding the differential effects of surgical volume reduction therapy (LVRS) and BLVR on lung and chest wall physiology will assist physicians in selecting an optimal approach for patients. OBJECTIVES: Determine ...
Hart Nicholas - - 2005
OBJECTIVE: To determine whether a custom girdle, designed to provide truncal stability and abdominal support, will improve pulmonary function, enhance inspiratory muscle activity, and reduce the sensation of respiratory effort in patients with spinal cord injury (SCI). DESIGN: Pulmonary function, transdiaphragmatic pressure time product (PTP di ), twitch (Tw Pdi) ...
Hoffman Andrew M - - 2005
OBJECTIVE: To determine whether tension of the girth strap of a saddle would sufficiently affect rib motion and reduce lung volume to alter pulmonary resistance in horses. ANIMALS: 10 healthy adult horses. PROCEDURE: We used classical techniques to measure the effects of tightening a girth strap (15 kg of tension) ...
Lindholm Peter - - 2005
Competitive breath-hold divers use glossopharyngeal breathing in order to increase their performance. Glossopharyngeal inhalation (GI) increases the volume of air in the lungs above the total lung capacity, thereby increasing the volume of gas available for pressure equalization at great depth. The reverse procedure, glossopharyngeal exhalation (GE), is used to ...
De Troyer André - - 2005
At resting end expiration [functional residual capacity (FRC)], the actions of the left and right hemidiaphragms on the lung are synergistic. However, the synergism decreases in magnitude as muscle tension decreases. Therefore, the hypothesis was tested in anesthetized dogs that the degree of synergism between the two hemidiaphragms also decreases ...
Miller Thomas L - - 2005
Surfactant and musculoskeletal immaturity results in lower compliance of the lung relative to the chest wall, with clinical manifestations of low lung volume, marked chest wall retractions (CWR), and thoracoabdominal asynchrony. Inspiratory efforts are dissipated on distorting the chest wall inward rather than recruiting lung volumes. The current study tests ...
Sharafkhaneh A - - 2005
BACKGROUND: Thoracic gas compression (TGC) exerts a negative effect on forced expiratory flow. Lung resistance, effort during a forced expiratory manoeuvre, and absolute lung volume influence TGC. Lung volume reduction surgery (LVRS) reduces lung resistance and absolute lung volume. LVRS may therefore reduce TGC, and such a reduction might explain ...
Boriek Aladin M - - 2005
Both diaphragm shape and tension contribute to transdiaphragmatic pressure, but of the three variables, tension is most difficult to measure. We measured transdiaphragmatic pressure and the global shape of the in vivo canine diaphragm and used principles of mechanics to compute the tension distribution. Our hypotheses were that 1) tension ...
Barbini Paolo - - 2005
A nonlinear dynamic morphometric model of breathing mechanics during artificial ventilation is described. On the basis of the Weibel symmetrical representation of the tracheo-bronchial tree, the model accurately accounts for the geometrical and mechanical characteristics of the conductive zone and packs the respiratory zone into a viscoelastic Voigt body. The ...
Cocito Dario - - 2005
Alterations of the phrenic nerve (PN) and pulmonary function tests (PFTs) have been described in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). This study was aimed at assessing the relationship between PN and respiratory function in CIDP patients without clinical signs of respiratory failure. Bilateral PN and right median nerve ...
Spahija Jadranka - - 2005
Increased transdiaphragmatic pressure, reduced muscle blood flow, and increased duty cycle have all been associated with a reduction in the center frequency (CFdi) of the diaphragm's electrical activity (EAdi). However, the specific influence of diaphragm activation on CFdi is unknown. We evaluated whether increased diaphragm activation would result in a ...
Pestaña D - - 2005
BACKGROUND AND OBJECTIVE: Although the pressure-volume (P-V) curve has been proposed in the management of mechanically ventilated patients, its interpretation remains unclear. Our aim has been to study the variations of the P-V curve after a recruitment manoeuvre (RM). Our hypothesis was that the lower inflection point (LIP) represents the ...
Xisto Debora G - - 2005
This study tested the hypotheses that chronic allergic inflammation induces not only bronchial but also lung parenchyma remodeling, and that these histologic changes are associated with concurrent changes in respiratory mechanics. For this purpose, airway and lung parenchyma remodeling were evaluated by quantitative analysis of collagen and elastin, immunohistochemistry (smooth-muscle ...
Graham M Ruth - - 2005
BACKGROUND: With biologically variable ventilation [BVV--using a computer-controller to add breath-to-breath variability to respiratory frequency (f) and tidal volume (VT)] gas exchange and respiratory mechanics were compared using the ARDSNet low VT algorithm (Control) versus an approach using mathematical modelling to individually optimise VT at the point of maximal compliance ...
Dosman Cara F - - 2005
The purpose of the present literature summary is to describe high-frequency chest compression (HFCC), summarize its history and outline study results on its effect on mucolysis, mucus transport, pulmonary function and quality of life. HFCC is a mechanical method of self-administered chest physiotherapy, which induces rapid air movement in and ...
Felekis Vasilios A - - 2005
This paper maintains that negative intrapleural pressure is a prerequisite for the appearance of emphysema, either simply by the enlargement of the air space in combination with elastolytic enzymatic factors, or, frequently, by its contribution to the breakdown of collagen and elastin fibers through the increase in intrapulmonary pressures. Hence ...
Hsu Chia-Lin - - 2005
BACKGROUND AND PURPOSE: The negative expiratory pressure (NEP) method offers a simple and rapid assessment of expiratory flow limitation (EFL) during tidal respiration. This study compared the value of NEP in the assessment of the bronchodilator test (BDT) with those of spirometry and the interrupter method. METHODS: Thirty two patients ...
Halvorsen Thomas - - 2005
Thoracic gas volume (Vtg) can be measured with body plethysmography by either repetitive panting or one single inspiratory effort against a shutter occluding the airways. The panting technique is preferred, but may be demanding. We aimed to assess the precision of these two methods and the degree of agreement between ...
Harris R Scott - - 2005
The quasi-static pressure-volume (P-V) curve of the respiratory system describes the mechanical behavior of the lungs and chest wall during inflation and deflation. To eliminate resistive and convective acceleration effects, the measurement of volume and pressure must be performed during short periods of apnea or during very slow flow. There ...
Tzelepis George E - - 2005
Peak expiratory flow (PEF) has previously been considered an effort-dependent, non flow-limited parameter that is constrained by the force-velocity relationship of the respiratory muscles. It has also been assumed that, if the muscles were able to augment the expiratory pressure, the PEF would increase. We tested the validity of this ...
Jonson Björn - - 2005
The principal features of elastic pressure-volume curves of lungs or the respiratory system (P(el)/V curves) recorded during reexpansion of collapsed lungs and subsequent deflation have been known since the 1950s. In acute respiratory failure and acute respiratory distress syndrome such curves have recently attracted increasing interest because new knowledge can ...
Thorevska Natalya Y - - 2004
BACKGROUND: Previous in vivo data suggest that high airway resistance (R(aw)) promotes dynamic hyperinflation, especially when coupled to high minute ventilation (V(E)). However, no studies have systematically examined the relative effects of various mechanical parameters on dynamic hyperinflation. METHODS: Intrinsic positive end-expiratory pressure (PEEPi) was measured with a ventilator-lung model, ...
Hart Nicholas - - 2004
BACKGROUND: The effect of nutritional status and lung disease progression on diaphragm strength in young patients with cystic fibrosis remains unclear. OBJECTIVE: The aim of this study was to investigate the effect of nutritional status and airway obstruction on diaphragm strength. DESIGN: Twitch transdiaphragmatic pressure (Tw Pdi) obtained by bilateral ...
Lavorini Federico - - 2004
This study aimed at evaluating changes in airway patency, lung volumes and perception of breathing discomfort intensity following salbutamol administration via the Diskus dry-powder inhaler (DPI) or a pressurized metered-dose inhaler with the Volumatic valved holding chamber (pMDI + Volumatic) in asthmatic patients with methacholine-induced bronchoconstriction. On six different study ...
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