MOUTH PRESSURE MAY OVERESTIMATE LUNG VOLUME IN PATIENTS WITH EXPIRATORY FLOW LIMITATION

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.

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Expiratory flow limitation during exercise in competition cyclists

Journal of Applied Physiology ◽

10.1152/jappl.1999.86.2.611 ◽

1999 ◽

Vol 86 (2) ◽

pp. 611-616 ◽

Cited By ~ 41

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.

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Effects of arm bracing on expiratory flow limitation and lung volume in elderly COPD patients

Physiotherapy ◽

10.1016/j.physio.2015.03.2024 ◽

2015 ◽

Vol 101 ◽

pp. e1121-e1122

Author(s):

T. Ogino ◽

K. Mase ◽

M. Nozoe ◽

T. Wada ◽

Y. Uchiyama ◽

...

Keyword(s):

Lung Volume ◽

Flow Limitation ◽

Expiratory Flow Limitation ◽

Copd Patients ◽

Expiratory Flow

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Lung volumes and expiratory flow limitation during exercise in interstitial lung disease

Journal of Applied Physiology ◽

10.1152/jappl.1994.77.2.963 ◽

1994 ◽

Vol 77 (2) ◽

pp. 963-973 ◽

Cited By ~ 54

Author(s):

D. D. Marciniuk ◽

G. Sridhar ◽

R. E. Clemens ◽

T. A. Zintel ◽

C. G. Gallagher

Keyword(s):

Interstitial Lung Disease ◽

Lung Disease ◽

Lung Volume ◽

Total Lung Capacity ◽

Flow Limitation ◽

Expiratory Flow Limitation ◽

Lung Volumes ◽

Lung Capacity ◽

Ventilatory Capacity ◽

Expiratory Flow

Lung volumes were measured at rest and during exercise by an open-circuit N2-washout technique in patients with interstitial lung disease (ILD). Exercise tidal flow-volume (F-V) curves were also compared with maximal F-V curves to investigate whether these patients demonstrated flow limitation. Seven patients underwent 4 min of constant work rate bicycle ergometer exercise at 40, 70, and 90% of their previously determined maximal work rates. End-expiratory lung volume and total lung capacity were measured at rest and near the end of each period of exercise. There was no significant change in end-expiratory lung volume or total lung capacity when resting measurements were compared with measurements at 40, 70, and 90% work rates. During exercise, expiratory flow limitation was evident in four patients who reported stopping exercise because of dyspnea. In the remaining patients who discontinued exercise because of leg fatigue, no flow limitation was evident. In all patients, the mean ratio of maximal minute ventilation to maximal ventilatory capacity (calculated from maximal F-V curves) was 67%. We conclude that lung volumes during exercise do not significantly differ from those at rest in this population and that patients with ILD may demonstrate expiratory flow limitation during exercise. Furthermore, because most patients with ILD are not breathing near their maximal ventilatory capacity at the end of exercise, we suggest that respiratory mechanics are not the primary cause of their exercise limitation.

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Expiratory flow limitation and regulation of end-expiratory lung volume during exercise

Journal of Applied Physiology ◽

10.1152/jappl.1993.74.5.2552 ◽

1993 ◽

Vol 74 (5) ◽

pp. 2552-2558 ◽

Cited By ~ 58

Author(s):

R. Pellegrino ◽

V. Brusasco ◽

J. R. Rodarte ◽

T. G. Babb

Keyword(s):

Lung Volume ◽

Breathing Pattern ◽

Airflow Obstruction ◽

Forced Expiratory Volume ◽

Flow Limitation ◽

Expiratory Flow Limitation ◽

Reflex Mechanism ◽

Forced Expiratory Flow ◽

Expiratory Flow ◽

The Impact

To investigate the impact of expiratory flow limitation (FL) on breathing pattern and end-expiratory lung volume (EELV), we imposed a small expiratory threshold load for a few breaths during exercise in nine volunteers (29–62 yr): six were healthy and three had mild-to-moderate airflow obstruction (67–71% predicted forced expiratory volume in 1 s). Six subjects showed evidence of FL, i.e., tidal expiratory flow impinging on maximal forced expiratory flow, at one or more exercise levels. Whenever an expiratory threshold load was imposed, mean expiratory flow decreased (P < 0.02) in association with an increased expiratory time (TE; P < 0.05). When the load was imposed during non-FL conditions, TE increased less than expiratory flow decreased and EELV tended to increase. In contrast, during FL, with the load, TE increased more than expiratory flow decreased, subjects did not achieve maximal expiratory flow until a lower volume, and EELV decreased (P < 0.001). Under both FL and no-FL conditions, unloading reversed the changes associated with loading. These data indicate that the increase in EELV during exercise is linked to the occurrence of FL. We suggest that compression of airways downstream from the flow-limiting segment may elicit a reflex mechanism that influences breathing pattern by terminating expiration prematurely, thus increasing EELV.

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Effects of Arm Bracing on Expiratory Flow Limitation and Lung Volume in Elderly COPD Subjects

Respiratory Care ◽

10.4187/respcare.03945 ◽

2015 ◽

Vol 60 (9) ◽

pp. 1282-1287 ◽

Cited By ~ 7

Author(s):

T. Ogino ◽

K. Mase ◽

M. Nozoe ◽

T. Wada ◽

Y. Uchiyama ◽

...

Keyword(s):

Lung Volume ◽

Flow Limitation ◽

Expiratory Flow Limitation ◽

Expiratory Flow

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A Pilot Study of Expiratory Flow Limitation and Lung Volume Reduction Surgery

CHEST Journal ◽

10.1378/chest.116.6.1762 ◽

1999 ◽

Vol 116 (6) ◽

pp. 1762-1771 ◽

Cited By ~ 6

Author(s):

Ron Dueck ◽

Sheila Cooper ◽

David Kapelanski ◽

Henri Colt ◽

Jack Clausen

Keyword(s):

Pilot Study ◽

Lung Volume ◽

Volume Reduction ◽

Flow Limitation ◽

Lung Volume Reduction Surgery ◽

Lung Volume Reduction ◽

Expiratory Flow Limitation ◽

Expiratory Flow

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Modeling expiratory flow from excised tracheal tube laws

Journal of Applied Physiology ◽

10.1152/jappl.1999.87.5.1973 ◽

1999 ◽

Vol 87 (5) ◽

pp. 1973-1980 ◽

Cited By ~ 11

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.

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