Albuterol may improve ventilation and exercise capacity in individuals exposed to secondhand tobacco smoke (SHS) who have preserved spirometry and lung volumes suggestive of air trapping, according to a study in BMC Pulmonary Medicine.
The double-blinded, randomized, crossover, placebo-controlled trial evaluated use of albuterol for improving exercise capacity and respiratory symptoms in nonsmoking SHS-exposed individuals at risk for chronic obstructive pulmonary disease (COPD) resulting from occupational exposure to SHS and with preserved spirometry and physiologic evidence of air trapping.
Air trapping was defined as having an absolute residual volume-to-total lung capacity (RV/TLC) value of greater than 0.35 on plethysmography or the presence of expiratory flow limitation (EFL).
Participants were past or current US commercial airline flight crewmembers from an observational study that assessed the potential adverse health effects of the aircraft cabin environment, such as exposure to occupational SHS. Eligible crewmembers were aged 40 to 80 years, nonsmoking, had worked onboard a plane for at least 1 year before the tobacco smoking ban in aircraft, and had preserved spirometry.
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[A]ir trapping in the setting of pre-COPD (tobacco-exposed persons with preserved spirometry) may be related to small airway disease that is not considered significant by spirometric indices of airflow obstruction.
The individuals were randomized to receive albuterol or placebo as their first inhaler from June 6, 2016, to February 27, 2020. They were instructed to take 2 inhalations of either albuterol (2 inhalations; 180 mcg) or placebo twice daily for 4 weeks before a repeat assessment.
The primary outcome was peak oxygen consumption (VO2) on cardiopulmonary exercise testing (CPET). Secondary outcomes included improvement in other CPET indices such as EFL and dynamic hyperinflation, symptoms, quality of life, and daily level of physical activity.
A total of 42 patients completed the full study, and 7 participants who completed the second visit also were included in the analysis. They had a mean (SD) age of 66.2 (8.0) years, and 88% were female. Of the 49 participants, 27 had air trapping by RV/TLC greater than 0.35 at baseline and at least 90% adherence to inhaler use.
Treatment adherence in the albuterol group was 87% vs 93% in the control group (P =.349), and no serious adverse events were observed.
In the primary analysis for all 49 participants, no significant change occurred in the primary or secondary outcomes in the intention-to-treat or per-protocol analyses.
In subgroup analysis that focused on RV/TLC greater than 0.35 and/or level of adherence to treatment protocol, a gradual increase in improvement was observed in the primary outcome of peak VO2 response, which was statistically significant with increasing adherence to treatment.
In the per-protocol subgroup analysis of 27 individuals with RV/TLC greater than 0.35 and at least 90% adherence, albuterol inhalation was associated with a significant improvement in peak VO2 (parameter estimate, 0.108; 95% CI, 0.014-0.202), and some secondary outcomes: tidal volume (0.084; 95% CI, 0.028-0.140), minute ventilation (4.242; 95% CI, 0.983-7.500), oxygen-pulse (0.688; 95% CI, 0.337-1.039), and some dynamic hyperinflation indices. No significant changes occurred in physical activity, symptoms, or quality of life.
Limitations include the small sample size and use of albuterol, a short-acting β-agonist bronchodilator. Also, evaluating air trapping in preserved spirometry may have been better in a population with more severe air trapping but preserved spirometry.
“This study suggests that air trapping in the setting of pre-COPD (tobacco-exposed persons with preserved spirometry) may be related to small airway disease that is not considered significant by spirometric indices of airflow obstruction,” the study authors stated.
