Search Results
Results 201 - 250 of 1421
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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 ...
Mitrouska I - - 2004
The accumulation of pleural effusion has important effects on respiratory system function. It changes the elastic equilibrium volumes of the lung and chest wall, resulting in a restrictive ventilatory effect, chest wall expansion and reduced efficiency of the inspiratory muscles. The magnitude of these alterations depends on the pleural fluid ...
Wada Hironobu - - 2004
A case of dramatic improvement of respiratory function after lobectomy for bullous emphysema with severe hyperinflation of the left lower lobe was reported. A 72-year-old gentleman was admitted to our hospital due to increasing dyspnea with Hugh-Johns class V. His chest X-ray and computed tomography revealed a hyperinflation of the ...
Ito Satoru - - 2005
Enlargement of the respiratory air spaces is associated with the breakdown and reorganization of the connective tissue fiber network during the development of pulmonary emphysema. In this study, a mouse (C57BL/6) model of emphysema was developed by direct instillation of 1.2 IU of porcine pancreatic elastase (PPE) and compared with ...
Markhorst Dick G - - 2004
OBJECTIVE: To study the value of objective pressure-volume characteristics for predicting optimal airway pressures and the development of atelectasis and overstretching during a structured lung volume recruitment procedure with subsequent reduction in airway pressures. METHODS: We used a mathematical model of a lung with adjustable characteristics of acute respiratory distress ...
Foley David S - - 2004
Expiratory flow limitation occurs during total liquid ventilation (TLV), and is characterized by the sudden development of excessively negative intratracheal pressures without increases in flow. The purpose of this study was to identify a dynamic signal for the servoregulation of expiratory flow (Ve), by determining the range of dynamic intratracheal ...
Maeda Yoshiko - - 2004
BACKGROUND: A lung-protecting strategy is essential when ventilating acute lung injury/acute respiratory distress syndrome patients. Current emphasis is on limiting inspiratory pressure and volume. This study was designed to investigate the effect of peak inspiratory flow on lung injury. METHODS: Twenty-four rabbits were anesthetized, tracheostomized, ventilated with a Siemens Servo ...
Nakamura Yoichi - - 2004
OBJECTIVE: The purpose of this study was to examine whether activities parallel to daily living (APDL) constitute a determinant index of cardiorespiratory fitness in patients with chronic obstructive pulmonary disease (COPD). METHODOLOGY: Four functional physical fitness parameters were investigated in 38 male patients (mean age 69.8 +/- 6.7 years) with ...
Sharma Mukesh - - 2004
In this study, the authors assessed the relationship between daily changes in respiratory health and particulate levels with diameters of (a) less than 10 microm (PM10) and (b) less than 2.5 microm (PM2.5) in Kanpur, India. The subjects (N = 91) were recruited from 3 areas in Kanpur: (1) Indian ...
Johnson Arthur T - - 2004
The airflow perturbation device (APD) is a recently redesigned instrument to measure resistance in the respiratory system. The APD is small and easy to use, gives rapid resistance measurements, and can easily separate inhalation from exhalation components. It also possesses some operational characteristics similar to forced oscillation (FO). Excised sheep ...
Tepper Robert S - - 2004
Respiratory system compliance (Crs) in infants with cystic fibrosis (CF) has been reported as decreased or not different compared with healthy control subjects; however, the reported measurements of Crs were "quasi-static" or by the single-breath occlusion technique, with all measurements limited to tidal lung volume, as well as using inspiratory ...
Laghi Franco - - 2004
STUDY OBJECTIVES: We previously reported that patients with emphysema show an increase in diaphragmatic neuromechanical coupling at 3 months after lung volume reduction surgery. Diaphragmatic neuromechanical coupling was quantified as the quotient of tidal volume (normalized to total lung capacity) to tidal change in transdiaphragmatic pressure (normalized to maximal transdiaphragmatic ...
Gattinoni Luciano - - 2004
The importance of chest wall elastance in characterizing acute lung injury/acute respiratory distress syndrome patients and in setting mechanical ventilation is increasingly recognized. Nearly 30% of patients admitted to a general intensive care unit have an abnormal high intra-abdominal pressure (due to ascites, bowel edema, ileus), which leads to an ...
Dimitriou G - - 2004
BACKGROUND: Infants with severe respiratory failure are frequently transferred to high volume strategy, high frequency oscillation (HFO). Mean airway pressure (MAP) is then elevated, the aim being to open up atelectatic lungs and hence improve gas exchange. AIM: To test the hypothesis that lung volume prior to transfer would predict ...
Peces-Barba G - - 2004
We evaluated the effect of prone positioning on gas-transfer characteristics in normal human subjects. Single-breath (SB) and rebreathing (RB) maneuvers were employed to assess carbon monoxide diffusing capacity (DlCO), its components related to capillary blood volume (Vc) and membrane diffusing capacity (Dm), pulmonary tissue volume (Vti), and cardiac output (Qc). ...
Hantos Z - - 2004
The aim of this study was to test the hypothesis that the mechanism of recruitment and the lower knee of the pressure-volume curve in the normal lung are primarily determined by airway reopenings via avalanches rather than simple alveolar recruitments. In isolated dog lung lobes, the pressure-volume loops were measured, ...
Grasso Salvatore - - 2004
OBJECTIVE: To evaluate whether the shape of the airway pressure-time (Paw-t) curve during constant flow inflation corresponds to radiologic evidence of tidal recruitment or tidal hyperinflation in an experimental model of acute lung injury. DESIGN: Prospective randomized laboratory animal investigation. SETTING: Department of Clinical Physiology, University of Uppsala, Sweden. SUBJECTS: ...
Zecha-Stallinger Angelika - - 2004
When ventilating an unintubated patient with a standard adult self-inflating bag, high peak inspiratory flow rates may result in high peak airway pressures with subsequent stomach inflation. In a previous study we have tested a newly developed mouth-to-bag-resuscitator (max. volume, 1500 ml) that limits peak inspiratory flow, but the possible ...
Verschuren Franck - - 2004
STUDY OBJECTIVE: To compare the diagnostic performance of volumetric capnography (VCap), which is the plot of the expired CO(2) partial pressure against the expired volume during a single breath, with the PaCO(2) to end-tidal CO(2) (EtCO(2)) gradient, in the case of suspected pulmonary embolism (PE). DESIGN: Single-center, prospective study. SETTING: ...
Dellacà Raffaele L - - 2004
We simultaneously evaluated the mechanical response of the total respiratory system, lung, and chest wall to changes in posture and to bronchoconstriction. We synthesized the optimal ventilation waveform (OVW) approach, which simultaneously provides ventilation and multifrequency forcing, with optoelectronic plethysmography (OEP) to measure chest wall flow globally and locally. We ...
Black Lauren D - - 2004
Measures of airway resistance (Raw) during deep inspiration (DI) suggest that asthmatic subjects possess stiffer, more reactive airway smooth muscle. There is evidence that one can enhance airway reactivity in healthy lungs by prohibiting DI for an extended period. The present study had two goals. First, we determined whether the ...
Downie John M - - 2004
To better understand strategies for recruiting and maintaining lung volume in acute lung injury, we examined relationships between steady-state lung volume and cumulative cyclic recruitment/derecruitment volume history and the quasi-static pressure-volume curve, in an animal saline lavage lung injury model. Small-volume tidal pressure-volume loops performed after inflation from functional residual ...
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