Abstract
Background Obese children with asthma are more vulnerable to air pollution, especially fine particulate matter (PM2.5), but reasons are poorly understood. We hypothesised that differences in breathing patterns (tidal volume, respiratory rate and minute ventilation) due to elevated body mass index (BMI) may contribute to this finding.
Objective To investigate the association of BMI with breathing patterns and deposition of inhaled PM2.5.
Methods Baseline data from a prospective study of children with asthma were analysed (n=174). Tidal breathing was measured by a pitot-tube flowmeter, from which tidal volume, respiratory rate and minute ventilation were obtained. The association of BMI z-score with breathing patterns was estimated in a multivariable model adjusted for age, height, race, sex and asthma severity. A particle dosimetry model simulated PM2.5 lung deposition based on BMI-associated changes in breathing patterns.
Results Higher BMI was associated with higher tidal volume (adjusted mean difference (aMD) between obese and normal-range BMI of 25 mL, 95% CI 5–45 mL) and minute ventilation (aMD 453 mL·min−1, 95% CI 123–784 mL·min−1). Higher tidal volumes caused higher fractional deposition of PM2.5 in the lung, driven by greater alveolar deposition. This translated into obese participants having greater per-breath retention of inhaled PM2.5 (aMD in alveolar deposition fraction of 3.4%, 95% CI 1.3–5.5%), leading to worse PM2.5 deposition rates.
Conclusions Obese children with asthma breathe at higher tidal volumes that may increase the efficiency of PM2.5 deposition in the lung. This finding may partially explain why obese children with asthma exhibit greater sensitivity to air pollution.
Abstract
Changes in breathing patterns due to obesity may explain why obesity increases susceptibility to air pollution https://bit.ly/36768Pk
Footnotes
This article has an editorial commentary: https://doi.org/10.1183/13993003.02505-2021
Conflict of interest: N. Afshar-Mohajer has nothing to disclose.
Conflict of interest: T.D. Wu has nothing to disclose.
Conflict of interest: R. Shade has nothing to disclose.
Conflict of interest: E. Brigham reports grants from the National Institute for Environmental Health Sciences, during the conduct of the study.
Conflict of interest: H. Woo has nothing to disclose.
Conflict of interest: M. Wood has nothing to disclose.
Conflict of interest: R. Koehl has nothing to disclose.
Conflict of interest: K. Koehler has nothing to disclose.
Conflict of interest: J. Kirkness reports other (salary) from 4DMedical, outside the submitted work.
Conflict of interest: N.N. Hansel reports grants from NIH and COPD Foundation, grants and personal fees for advisory board work from AstraZeneca and GSK, grants from Boehringer Ingelheim, personal fees for advisory board work from Mylan during the conduct of the study.
Conflict of interest: G. Ramachandran has nothing to disclose.
Conflict of interest: M.C. McCormack reports grants from National Institutes of Health (P50ES018176) and Environmental Protection Agency (83615201), during the conduct of the study; other (authorship royalties) from UpToDate, personal fees for consultancy from Aridis, GlaxoSmithKline and Celgene, outside the submitted work.
Support statement: Technology described in this manuscript was supported by an SBIR award from the National Heart, Lung, and Blood Institute (R44HL091687). E. Brigham, K. Koehler, N.N. Hansel and M.C. McCormack are supported by the National Institute of Environmental Health Sciences (K. Koehler, N.N. Hansel and M.C. McCormack: P50ES018176; E. Brigham: K23ES029105) and by the United States Environmental Protection Agency (83615201 and 83615001). T.D. Wu is supported by the National Heart, Lung, and Blood Institute (K23HL151669) and by the Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, Center for Innovation in Quality, Effectiveness and Safety (CIN 13-413). This work is the sole responsibility of the authors and does not necessarily represent the views of the National Institutes of Health, the Department of Veterans Affairs, the Environmental Protection Agency, or the United States government. Funding information for this article has been deposited with the Crossref Funder Registry.
- Received January 23, 2021.
- Accepted June 30, 2021.
- Copyright ©The authors 2022. For reproduction rights and permissions contact permissions{at}ersnet.org