Extent of expiratory flow limitation influences the increase in maximal exercise ventilation in hypoxia

1998 ◽  
Vol 113 (1) ◽  
pp. 65-74 ◽  
Author(s):  
R.F. Chapman ◽  
M. Emery ◽  
J.M. Stager
Keyword(s):  
Maximal Exercise ◽  
Flow Limitation ◽  
Expiratory Flow Limitation ◽  
Exercise Ventilation ◽  
Expiratory Flow

Expiratory flow limitation during exercise in competition cyclists

1999 ◽  
Vol 86 (2) ◽  
pp. 611-616 ◽  
Author(s):  
Susana Mota ◽  
Pere Casan ◽  
Franchek Drobnic ◽  
Jordi Giner ◽  
Olga Ruiz ◽  
...  
Keyword(s):  
Lung Volume ◽  
Exercise Test ◽  
Maximal Exercise ◽  
Peak Exercise ◽  
Flow Limitation ◽  
Expiratory Flow Limitation ◽  
Exercise Ventilation ◽  
Aerobic Exercise Capacity ◽  
Expiratory Flow ◽  
Maximal Voluntary Ventilation

In some trained athletes, maximal exercise ventilation is believed to be constrained by expiratory flow limitation (FL). Using the negative expiratory pressure method, we assessed whether FL was reached during a progressive maximal exercise test in 10 male competition cyclists. The cyclists reached an average maximal O2 consumption of 72 ml ⋅ kg−1 ⋅ min−1(range: 67–82 ml ⋅ kg−1 ⋅ min−1) and ventilation of 147 l/min (range: 122–180 l/min) (88% of preexercise maximal voluntary ventilation in 15 s). In nine subjects, FL was absent at all levels of exercise (i.e., expiratory flow increased with negative expiratory pressure over the entire tidal volume range). One subject, the oldest in the group, exhibited FL during peak exercise. The group end-expiratory lung volume (EELV) decreased during light-to-moderate exercise by 13% (range: 5–33%) of forced vital capacity but increased as maximal exercise was approached. EELV at peak exercise and at rest were not significantly different. The end-inspiratory lung volume increased progressively throughout the exercise test. The conclusions reached are as follows: 1) most well-trained young cyclists do not reach FL even during maximal exercise, and, hence, mechanical ventilatory constraint does not limit their aerobic exercise capacity, and 2) in absence of FL, EELV decreases initially but increases during heavy exercise.

Expiratory Flow Limitation And Ventilatory Responses To Inspiratory Loading And Maximal Exercise In Trained Cyclists

2011 ◽  
Vol 43 (Suppl 1) ◽  
pp. 632-633
Author(s):  
Sandy Tecklenburg-Lund ◽  
Louise A. Turner ◽  
Robert F. Chapman ◽  
Joel M. Stager ◽  
Timothy D. Mickleborough
Keyword(s):  
Maximal Exercise ◽  
Flow Limitation ◽  
Expiratory Flow Limitation ◽  
Ventilatory Responses ◽  
Expiratory Flow

Modeling expiratory flow from excised tracheal tube laws

1999 ◽  
Vol 87 (5) ◽  
pp. 1973-1980 ◽  
Author(s):  
Nikolai Aljuri ◽  
Lutz Freitag ◽  
José G. Venegas
Keyword(s):  
Static Pressure ◽  
Pressure Recovery ◽  
High Frequency Ventilation ◽  
Flow Limitation ◽  
Flow Conditions ◽  
Expiratory Flow Limitation ◽  
Elastic Tubes ◽  
Viscous Losses ◽  
Forced Expiratory Flow ◽  
Expiratory Flow

Flow limitation during forced exhalation and gas trapping during high-frequency ventilation are affected by upstream viscous losses and by the relationship between transmural pressure (Ptm) and cross-sectional area ( A tr) of the airways, i.e., tube law (TL). Our objective was to test the validity of a simple lumped-parameter model of expiratory flow limitation, including the measured TL, static pressure recovery, and upstream viscous losses. To accomplish this objective, we assessed the TLs of various excised animal tracheae in controlled conditions of quasi-static (no flow) and steady forced expiratory flow. A tr was measured from digitized images of inner tracheal walls delineated by transillumination at an axial location defining the minimal area during forced expiratory flow. Tracheal TLs followed closely the exponential form proposed by Shapiro (A. H. Shapiro. J. Biomech. Eng. 99: 126–147, 1977) for elastic tubes: Ptm = K p[( A tr/ A tr0)− n − 1], where A tr0 is A tr at Ptm = 0 and K p is a parametric factor related to the stiffness of the tube wall. Using these TLs, we found that the simple model of expiratory flow limitation described well the experimental data. Independent of upstream resistance, all tracheae with an exponent n < 2 experienced flow limitation, whereas a trachea with n > 2 did not. Upstream viscous losses, as expected, reduced maximal expiratory flow. The TL measured under steady-flow conditions was stiffer than that measured under expiratory no-flow conditions, only if a significant static pressure recovery from the choke point to atmosphere was assumed in the measurement.

scholarly journals Clinical characteristics of COPD patients with tidal expiratory flow limitation

2017 ◽  
Vol Volume 12 ◽  
pp. 1503-1506 ◽  
Author(s):  
James Dean ◽  
Umme Kolsum ◽  
Paul Hitchen ◽  
Vanadana Gupta ◽  
Dave Singh
Keyword(s):  
Clinical Characteristics ◽  
Flow Limitation ◽  
Expiratory Flow Limitation ◽  
Copd Patients ◽  
Expiratory Flow

Expiratory flow limitation during exercise in prepubescent boys and girls: prevalence and implications

2010 ◽  
Vol 108 (5) ◽  
pp. 1267-1274 ◽  
Author(s):  
Katherine E. Swain ◽  
Sara K. Rosenkranz ◽  
Bethany Beckman ◽  
Craig A. Harms
Keyword(s):  
Body Composition ◽  
Oxygen Saturation ◽  
Tidal Volume ◽  
Lean Body Mass ◽  
Lung Volume ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Flow Limitation ◽  
Expiratory Flow Limitation ◽  
Expiratory Flow

The purpose of this study was to compare the prevalence and implications of expiratory flow limitation (EFL) during exercise in boys and girls. Forty healthy, prepubescent boys (B; n = 20) and girls (G; n = 20) were tested. Subjects completed pulmonary function tests and an incremental cycle maximal oxygen uptake (V̇o2max) test. EFL was recorded at the end of each exercise stage using the % tidal volume overlap method. Ventilatory and metabolic data were recorded throughout exercise. Arterial oxygen saturation (SpO2) was determined via pulse oximetry. Body composition was determined using dual-energy X-ray absorptiometry. There were no differences ( P > 0.05) in height, weight, or body composition between boys and girls. At rest, boys had significantly higher lung volumes (total lung capacity, B = 2.6 ± 0.5 liters, G = 2.1 ± 0.5 liters) and peak expiratory flow rates (B = 3.6 ± 0.6 l/s; G = 1.6 ± 0.3 l/s). Boys also had significantly higher V̇o2max (B = 46.9 ± 5.9 ml·kg lean body mass−1·min−1, G = 41.7 ± 6.6 ml·kg lean body mass−1·min−1) and maximal ventilation (B = 49.8 ± 8.8 l/min, G = 41.2 ± 8.3 l/min) compared with girls. There were no sex differences ( P > 0.05) at V̇o2max in VE /Vco2, end-tidal Pco2, heart rate, respiratory exchange ratio, or SpO2. The prevalence (B = 19/20 vs. G = 18/20) and severity (B = 58 ± 7% vs. G = 43 ± 8% tidal volume) of EFL was not significantly different in boys compared with girls at V̇o2max. A significant relationship existed between % EFL at V̇o2max and the change in end-expiratory lung volume from rest to maximal exercise in boys ( r = 0.77) and girls ( r = 0.75). In summary, our data suggests that EFL is highly and equally prevalent in prepubescent boys and girls during heavy exercise, which led to an increased end-expiratory lung volume but not to decreases in arterial oxygen saturation.

Influence of airway geometry on expiratory flow limitation and density dependence

1983 ◽  
Vol 52 (1) ◽  
pp. 113-123 ◽  
Author(s):  
Ronald J. Knudson ◽  
Robert C. Schroter ◽  
Dwyn E. Knudson ◽  
Stuart Sugihara
Keyword(s):  
Density Dependence ◽  
Flow Limitation ◽  
Expiratory Flow Limitation ◽  
Expiratory Flow
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