Effect of twice daily inhaled albuterol on cardiopulmonary exercise outcomes, dynamic hyperinflation, and symptoms in secondhand tobacco-exposed persons with preserved spirometry and air trapping: a randomized controlled trial

Table 2 Distributions of air trapping by the ratio of residual volume to total lung capacity (RV/TLC) and expiratory flow limitation (EFL)

	RV/TLC > 0.35 N = 35	RV/TLC ≤ 0.35 N = 14
Expiratory flow limitation
Had EFL at rest or during exercise	29 (82.9%)	14 (100%)^a
Had EFL at rest	19 (54.3%)	4 (28.6%)
Developed EFL during exercise	10 (28.6%)	10 (71.4%)
Dynamic hyperinflation
Had EELV increase across exercise	14 (40.0%)	7 (50.0%)

Footnote: Distributions of air trapping as measured by residual volume to total lung capacity ratio (RV/TLC), expiratory flow limitation (EFL) as measured graphic overlap of tidal breathing with maximum expiratory flow-volume loop, and dynamic hyperinflation as measured by an increased in end-expiratory lung volume (EELV) from baseline throughout the exercise, estimated from regression coefficient of three EELV measurements at each of baseline (rest), 20%, 40%, 60%, and 80% of the load intensity (watts) of the peak exercise stage achieved. Values represent number of participants and their percent of the total number in each of the RV/TLC groups of > 0.35 or ≤ 0.35. See text for detailed methods
Abbreviations: RV residual volume, TLC total lung capacity, EFL expiratory flow limitation, EELV end-expiratory lung volume
^aHaving EFL at rest or during exercise was a required inclusion criteria for those participants with RV/TLC ≤ 0.35

ISSN: 1471-2466