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Zeng S, Nishihama M, Weldemichael L, Lozier H, Gold WM, Arjomandi M. 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. BMC Pulm Med 2024; 24:44. [PMID: 38245665 PMCID: PMC10799390 DOI: 10.1186/s12890-023-02808-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 12/07/2023] [Indexed: 01/22/2024] Open
Abstract
BACKGROUND In tobacco-exposed persons with preserved spirometry (active smoking or secondhand smoke [SHS] exposure), air trapping can identify a subset with worse symptoms and exercise capacity. The physiologic nature of air trapping in the absence of spirometric airflow obstruction remains unclear. The aim of this study was to examine the underlying pathophysiology of air trapping in the context of preserved spirometry and to determine the utility of bronchodilators in SHS tobacco-exposed persons with preserved spirometry and air trapping. METHODS We performed a double-blinded placebo-controlled crossover randomized clinical trial in nonsmoking individuals at risk for COPD due to exposure to occupational SHS who had preserved spirometry and air trapping defined as either a residual volume-to-total lung capacity ratio (RV/TLC) > 0.35 or presence of expiratory flow limitation (EFL, overlap of tidal breathing on maximum expiratory flow-volume loop) on spirometry at rest or during cardiopulmonary exercise testing (CPET). Those with asthma or obesity were excluded. Participants underwent CPET at baseline and after 4-week trials of twice daily inhalation of 180 mcg of albuterol or placebo separated by a 2-week washout period. The primary outcome was peak oxygen consumption (VO2) on CPET. Data was analyzed by both intention-to-treat and per-protocol based on adherence to treatment prescribed. RESULTS Overall, 42 participants completed the entire study (66 ± 8 years old, 91% female; forced expiratory volume in 1 s [FEV1] = 103 ± 16% predicted; FEV1 to forced vital capacity [FVC] ratio = 0.75 ± 0.05; RV/TLC = 0.39 ± 0.07; 85.7% with EFL). Adherence was high with 87% and 93% of prescribed doses taken in the treatment and placebo arms of the study, respectively (P = 0.349 for comparison between the two arms). There was no significant improvement in the primary or secondary outcomes by intention-to-treat or per-protocol analysis. In per-protocol subgroup analysis of those with RV/TLC > 0.35 and ≥ 90% adherence (n = 27), albuterol caused an improvement in peak VO2 (parameter estimate [95% confidence interval] = 0.108 [0.014, 0.202]; P = 0.037), tidal volume, minute ventilation, dynamic hyperinflation, and oxygen-pulse (all P < 0.05), but no change in symptoms or physical activity. CONCLUSIONS Albuterol may improve exercise capacity in the subgroup of SHS tobacco-exposed persons with preserved spirometry and substantial air trapping. These findings suggest that air trapping in pre-COPD may be related to small airway disease that is not considered significant by spirometric indices of airflow obstruction.
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Affiliation(s)
- Siyang Zeng
- Department of Biomedical Informatics and Medical Education, University of Washington, Seattle, WA, USA
- Pulmonary and Critical Care Section, San Francisco Veterans Affairs Health Care System, Building 203, Room 3A-128, Mailstop 111-D, 4150 Clement Street, San Francisco, CA, 94121, USA
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, University of California, San Francisco, CA, USA
| | - Melissa Nishihama
- Pulmonary and Critical Care Section, San Francisco Veterans Affairs Health Care System, Building 203, Room 3A-128, Mailstop 111-D, 4150 Clement Street, San Francisco, CA, 94121, USA
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, University of California, San Francisco, CA, USA
| | - Lemlem Weldemichael
- Pulmonary and Critical Care Section, San Francisco Veterans Affairs Health Care System, Building 203, Room 3A-128, Mailstop 111-D, 4150 Clement Street, San Francisco, CA, 94121, USA
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, University of California, San Francisco, CA, USA
| | - Helen Lozier
- Pulmonary and Critical Care Section, San Francisco Veterans Affairs Health Care System, Building 203, Room 3A-128, Mailstop 111-D, 4150 Clement Street, San Francisco, CA, 94121, USA
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, University of California, San Francisco, CA, USA
- Carver College of Medicine, University of Iowa, Iowa City, USA
| | - Warren M Gold
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, University of California, San Francisco, CA, USA
| | - Mehrdad Arjomandi
- Pulmonary and Critical Care Section, San Francisco Veterans Affairs Health Care System, Building 203, Room 3A-128, Mailstop 111-D, 4150 Clement Street, San Francisco, CA, 94121, USA.
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, University of California, San Francisco, CA, USA.
- Department of Medicine, Division of Occupational, Environmental, and Climate Medicine, University of California, San Francisco, CA, USA.
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