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Results 351 - 400 of 826
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Kayser B - - 1997
Nine healthy subjects (age 31 +/- 4 yr) exercised with and without expiratory-flow limitation (maximal flow approximately 1 l/s). We monitored flow, end-tidal PCO2, esophageal (Pes) and gastric pressures, changes in end-expiratory lung volume, and perception (sensation) of difficulty in breathing. Subjects cycled at increasing intensity (+25 W/30 s) until ...
Prioux J - - 1997
We compared the effects of two step durations on breathing pattern, mouth occlusion pressure and "effective" impedance of the respiratory system during incremental exercise. Nine normal subjects (mean age: 27.8+/-1.21 years) performed two incremental exercise tests in randomized order: one test with step increments every 1 min 30s and the ...
Hirsch T - - 1997
This study was designed to compare the bronchodilatatory effect of terbutaline inhaled through Turbuhaler (TH) or pressurized metered-dose inhaler (pMDI) in young asthmatics, and to assess the possible relationship between patients' inspiratory capacity and bronchodilatation for both devices. One hundred and eighteen asthmatics (aged 4 10/12-20 6/12 years) with bronchial ...
Ayoub J - - 1997
PURPOSE: The standard conditions of spirometry (i.e., wearing a noseclip and breathing through a mouthpiece and a pneumotachograph) are likely to alter the ventilatory pattern. We used "time motion" mode (M-mode) sonography to assess the changes in diaphragm kinetics induced by spirometry during quiet breathing. METHODS: An M-mode sonographic study ...
Fahy B G - - 1997
How the effects of frequency, tidal volume (VT) and PEEP interact to determine the mechanical properties of the respiratory system is unclear. Airway flow and airway and esophageal pressures were measured in ten intubated, anesthetized/paralyzed patients during mechanical ventilation at 10-30 breaths/min and VT of 250-800 ml. From these measurements, ...
Bégin P - - 1997
We studied 134 patients with Steinert's myotonic dystrophy (MD) in order to determine the prevalence of chronic hypercapnia, the level of muscle weakness and forced expiratory volume at which hypercapnic respiratory failure is likely to occur, and how clinical assessment might help predict hypercapnic respiratory failure. Subjects were divided into ...
Meyer K - - 1997
We prospectively assessed whether baseline central hemodynamics and exercise capacity can predict improvement of VO2 at ventilatory threshold (VT) after exercise training in patients with severe chronic congestive heart failure. Eighteen patients (mean +/- SEM; age 52 +/- 2 years), half of them listed for transplant, underwent 3 weeks of ...
Keller C A - - 1997
Improved ventilation and exercise capacity follows thoracoscopic lung volume reduction surgery (TLVRS) in patients with severe emphysema. This improvement could be related to changes in inspiratory and expiratory flows following surgery, with consequent improvement in dyspnea indices. Changes in inspiratory/expiratory flows at rest and exercise and their relation to subjective ...
Chicharro J L - - 1997
OBJECTIVE: The purpose of this investigation was to study the relationship between the lactate (LT) and the ventilatory threshold (VT) during a ramp protocol in cycle ergometry. PARTICIPANTS: Thirty nine trained male subjects were selected as subjects. EXPERIMENTAL DESIGN: All the subjects performed a maximal ergometric test on a cycle ...
Lucía A - - 1997
The purpose of this study was to investigate the possible use of integrated surface electromyography (iEMG) in cardiac transplant patients (CTPs) as a new noninvasive determinant of the metabolic response to exercise by studying the relationship between the iEMG threshold (iEMGT) and other more conventional methods for anaerobic threshold (AT) ...
Brennick M J - - 1997
The genioglossus is an upper airway dilator muscle, the length of which is directly related to patency in the oropharyngeal region. We hypothesized that genioglossal length (Lgg) is dynamically influenced by the afterload exerted by negative upper airway pressure during inspiration and by the intrinsic length-tension characteristics of the muscle ...
Romero P V - - 1997
Several indices of ventilatory heterogeneity can be identified from the expiratory CO2 partial pressure or CO2 elimination versus volume curves. The aims of this study were: 1) to analyse several computerizable indices of volumetric capnography in order to detect ventilatory disturbances; and 2) to establish the relationship between those indices ...
McKenzie D K - - 1997
Task failure during inspiratory resistive loading is thought to be accompanied by substantial peripheral fatigue of the inspiratory muscles. Six healthy subjects performed eight resistive breathing trials with loads of 35, 50, 75 and 90% of maximal inspiratory pressure (MIP) with and without supplemental oxygen. MIP measured before, after, and ...
Peslin R - - 1997
Instantaneous respiratory effective elastance (Eteff) and tissue resistance (Rt) may be measured by studying the relationship between flow at the airway opening and at the chest during forced oscillations; using that method it has been shown that Rt varies little during breathing while Eteff presents much larger phasic variations than ...
Bhambhani Y N - - 1997
The onset of anaerobic (lactate) metabolism during incremental exercise, which may be a result of an imbalance between tissue oxygen supply and demand, has been associated with the gas exchange ventilatory threshold (VT). This study was designed to examine whether near infrared spectroscopy (NIRS) could be used to detect the ...
Lisboa C - - 1997
The effect of inspiratory muscle training (IMT) on exercise capacity in patients with chronic airflow limitation (CAL) has been debated. The present study was planned to further investigate the effects of IMT on exercise performance. Twenty patients (aged 62+/-1 yrs; forced expiratory volume in one second/forced vital capacity (FEV1/FVC) 36+/-2%) ...
Ito Y - - 1997
This study evaluated the effects of varying tidal volumes (VT) and positive end-expiratory pressure (PEEP) levels on surfactant aggregate conversion and lung function in an animal model of lung injury induced by N-nitroso-N-methylurethane. Lung-injured adult rabbits were initially ventilated using a VT of 10 ml/kg (VT10), a respiratory rate of ...
Rowland T W - - 1997
Cross-sectional studies have indicated that the pattern of ventilatory responses to exercise evolves during the course of childhood. This 5-year study was designed to provide a longitudinal assessment of minute ventilation (VE), tidal volume (VT), and breathing frequency (fR) in 20 children (11 girls, nine boys) between the ages of ...
Benditt J O - - 1997
Patients with chronic obstructive pulmonary disease have abnormal breathing and ventilatory muscle recruitment patterns at rest and during exercise, and these alterations may contribute to the limited exercise capacity seen in this disease. Lung volume reduction surgery (LVRS), a recently described treatment for emphysema, is reported to improve exercise performance. ...
Ferrari K - - 1997
In adolescent idiopathic thoracic scoliosis (ITS) working capacity may be reduced during exercise. Despite concern about its usefulness, bracing is still being used in ITS. Thus the effects of bracing on exercise performance need to be examined. We studied six females, ages 12-15 years who had mild ITS (Cobb angle ...
Jagadeesh J M - - 1997
The aim of this study was to determine how Wavelet transform analysis of signal-averaged ECGs can identify patients with conduction defects who are at high risk for development of ventricular tachycardia. In this study, 34 SA-ECGs and programmed electrical stimulation (PES) reports were obtained from the OSU Department of Cardiology ...
Vinet A - - 1997
The aims of the present study were: (1) to assess aerobic metabolism in paraplegic (P) athletes (spinal lesion level, T4-L3) by means of peak oxygen uptake (VO2peak) and ventilatory threshold (VT), and (2) to determine the nature of exercise limitation in these athletes by means of cardioventilatory responses at peak ...
O'Donnell D E - - 1997
We compared qualitative aspects of the sensory experience of exertional breathlessness in normal subjects and in patients with chronic airflow limitation (CAL) and sought a physiologic rationale for these. Twelve patients (66 +/- 2 yr of age, mean +/- SEM) with severe CAL (FEV1 = 37 +/- 5% predicted) and ...
Miyamura M - - 1997
The present study was performed to examine whether or not the ventilatory response at the onset of voluntary exercise and passive movement in endurance runners is the same as in untrained subjects. Twelve long-distance runners belonging to the varsity athletic club and 13 untrained subjects of our university participated as ...
Kelly M C - - 1996
We report the changes observed in a number of pulmonary function tests performed on 36 patients undergoing Caesarean section under spinal anaesthesia. The tests comprised peak expiratory flow, forced expiratory volume in one second, forced vital capacity, forced expiratory volume in one second to forced vital capacity ratio and the ...
Aizawa Y - - 1996
OBJECTIVES: The action of mexiletine on diseased myocardium was assessed in reentrant ventricular tachycardia (VT). BACKGROUND: Whether class Ib antiarrhythmic agents exert a preferential action on the central common pathway of reentrant ventricular tachycardia has not yet been studied in humans. METHODS: In 10 consecutive patients (7 with a previous ...
Nagashima M - - 1996
Exercise-induced ventricular tachycardia (VT) without demonstrable heart disease was studied in pediatric patients. The study population consisted of 17 patients aged 5-14 years (average 9.1 years), who demonstrated reproducible VT during or immediately after exercise testing using a treadmill. The main reasons for the exercise testing were episodes of exercise-related ...
Miller R L - - 1996
STUDY OBJECTIVE: Laryngotracheal injury or edema in the setting of intubation may narrow the upper airway and predispose toward postextubation stridor. The presence or absence of an audible airleak when the sealing balloon cuff of the endotracheal tube is deflated has been demonstrated to be a marker of laryngotracheal edema ...
Clague J E - - 1996
1. To examine the effects of sustained resistive loading on the relationship between inspiratory effort sensation and respiratory drive (P0.1) and to determine if the change in CO2 responsiveness after sustained loading is accompanied by altered effort perception, hypercapnic responses were measured before, immediately after and 15 min after sustained ...
Fothergill D M - - 1996
The influence of nitrous oxide (N2O) narcosis on the response to exercise and inspiratory resistive loading was studied in thirteen male US Navy divers. Each diver performed an incremental bicycle exercise test at 1 ATA to volitional exhaustion while breathing a 23% N2O gas mixture and a nonnarcotic gas of ...
Rafferty G F - - 1996
We studied in conscious humans the relative strength of mechanisms controlling timing and drive components of the respiratory cycle around their resting set points. A system of auditory feedback with end-tidal PCO2 held constant in mild hyperoxia via an open circuit was used to induce subjects independently to change inspiratory ...
Taylor A D - - 1996
This study analysed the effectiveness of an on-demand system of supplying pre-mixed inspiratory gases to subjects under working conditions. A supply of pre-mixed inspiratory gas is often required in order to study the effects of acute hypoxia/hyperoxia on numerous physiological variables whilst normobaric pressure is maintained. The principle aim of ...
Braggion C - - 1996
The time course of inspiration has been shown to have a significant influence on the subsequent maximal expiratory flows and timed forced expiratory volumes in healthy adults and those with COPD. The purpose of this study was to evaluate the effect of two different inspiratory maneuvers on the spirogram in ...
Spence D P - - 1996
Wheeze is a classic sign of airflow obstruction but relatively little is known of its mechanism of production or its relationship to the development of airflow obstruction. We studied eight asthmatic subjects age (mean +/- 5D) 42 +/- 5 yr, FEV1 2.46 +/- 0.36 L during an extended, symptom-limited methacholine ...
Muza S R - - 1996
This study examined the effects of added inspiratory resistance (R5 5 cm H2O.L-1.S-1) on the relationship between exercise breathing pattern and resting hypercapnic ventilatory responsiveness (HCVR). Twelve men completed an HCVR test and two progressive intensity exercise tasks with minimal (R0) and elevated (R5) resistance. Peak oxygen uptake, and peak ...
McConnell Timothy R. - - 1996
The minute ventilation (VE) and carbon dioxide output (VCO&sub2;) adaptations to 12 weeks of cardiac rehabilitation were investigated in diagnosis-matched elderly patients (ELD) and younger patients (YNG). Thirty ELD (25 males, 5 females; age equals 69.2Â+/-3.9 years) and 30 YNG (27 males, 3 females; age equals 48.3Â+/-7.0 years) were exercise ...
Fujimori K - - 1996
BACKGROUND: Conflicting results from previous studies on the effect of bronchial challenge on ventilatory patterns in asthmatics may be due to airflow obstruction present before induction of bronchospasm onset, as well as the different degrees of bronchoconstriction induced. PURPOSE AND METHODS: We examined the ventilatory response to stepwise increments in ...
Strömberg N O - - 1996
Breathing pattern variability was determined in 10 asthmatic adolescents during repeated bronchial histamine and methacholine challenges (HiCh/MeCh). The purpose was to provide information on ventilatory control in asthmatics by comparing the variability of the various breathing pattern parameters at rest and during induced bronchial obstruction. Changes in variability during bronchial ...
Fuller D - - 1996
The aim of our study was to describe the endurance capacity of the expiratory muscles and to determine whether it is altered after exhaustive cycling exercise. Subjects performed repeated maximal expiratory efforts against a closed breathing valve, with and without prior exercise performed at a work rate that elicited 75% ...
Puddy A - - 1996
The purpose of this study was to evaluate the extent of inhibition to respiratory rhythm associated with high volumes of ventilation during volume-cycled mechanical ventilation (neuromechanical inhibition). Two approaches were used. 1) In 18 normal awake subjects, ventilator tidal volume (VT) in the assist/control mode (A/C) was increased in steps ...
Webb B - - 1996
Expiratory loads elicit volume-dependent reflex increases in expiratory duration (TE) in adult animals. This reflex is mediated by pulmonary vagal afferents. It was hypothesized that this same reflex in newborn lambs is mediated by vagal afferents. Single-breath graded expiratory loads were presented to 4 day old, anesthetized neonatal lambs through ...
SliwiƄski P - - 1996
We evaluated the effect of global inspiratory muscle fatigue (GF) on respiratory muscle control during exercise at 30, 60, and 90% of maximal power output in normal subjects. Fatigue was induced by breathing against a high inspiratory resistance until exhaustion. Esophageal and gastric pressures, anteroposterior displacement of the rib cage ...
Gozal D - - 1996
During exercise, children with congenital central hypoventilation syndrome (CCHS) demonstrate coupling of VE to exercise load, despite the absence of a VE response to changes in FICO2. To assess the effect of movement on VE, we studied six CCHS patients and six matched controls during passive motion in a motor-driven ...
Krishnan B - - 1996
1. Seven active subjects (24 +/- 1 years; maximal oxygen uptake (VO2,max), 3.77 +/- 0.2 l min-1; mean +/- S.E.M.) performed constant work rate heavy exercise (CWHE, approximately 80% of maximal incremental work rate) to exhaustion on 2 days, one with (unload) and one without (control) respiratory muscle unloading. 2. ...
Dooly C R - - 1996
Respirator masks vary in inhalation and exhalation resistance, and in dead volume. It is believed that these factors may contribute significantly to an early anaerobic threshold in mask wearers during maximal exercise. Very little is known concerning the effect of respirator masks on maximal oxygen consumption (VO2max) and the lactate ...
Baydur A - - 1996
In kyphoscoliosis (KS), lung volumes are reduced, respiratory elastance and resistance are increased, and breathing pattern is rapid and shallow, attributes that may contribute to defense of tidal volume (VT) in the face of inspiratory resistive loading. The control of ventilation of 12 anesthetized patients about to undergo corrective spinal ...
Ohuchi H - - 1996
The purpose of the present study was to measure oxygen uptake (VO2) at the ventilatory threshold (VT) in patients with congenital heart disease using a progressive exercise protocol on a treadmill and to evaluate the validity and feasibility of this procedure. Eight control subjects and seventeen patients performed a maximal ...
Guazzi M - - 1995
Dead space/tidal volume ratio (VD/VT) evaluation is currently performed in patients with respiratory and cardiac disorders, and includes measurement of arterial CO2 partial pressure (PaCO2). PaCO2 is generally derived from either PETCO2 (end-expiratory CO2 pressure) or PJCO2 (calculated as PJCO2 = 5.5 + 0.9 PETCO2 - 2.1 VT). The applicability ...
Clark A L - - 1995
BACKGROUND: Patients with chronic heart failure have an excessive ventilatory response to exercise, characterised by an increase in the slope of the relation between ventilation and carbon dioxide production (VE/VCO2 slope). Patients have an altered respiratory pattern with an increased respiratory rate (f) at a given tidal volume (VT), which ...
Lougheed D M - - 1995
The effects of the inspiratory threshold load (ITL) on breathlessness and ventilatory mechanics during acute bronchoconstriction were studied by comparing responses to continuous positive airway pressure (CPAP) and inspiratory positive airway pressure (IPAP) in 12 asthmatic subjects after methacholine bronchoprovocation to a maximum change (delta) in FEV1 of 50%. At ...
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