Nima Afshar-Mohajer1,2,3, Tianshi David Wu4,5,6,3, Rebecca Shade7, Emily Brigham4, Han Woo4, Megan Wood4, Rachelle Koehl4, Kirsten Koehler1, Jason Kirkness8, Nadia N Hansel4, Gurumurthy Ramchandran1,9, Meredith C McCormack10,9. 1. Dept of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA. 2. Gradient Corporation, Division of Environmental Sciences, Boston, MA, USA. 3. Contributed equally to this work (first authors). 4. Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA. 5. Section of Pulmonary, Critical Care, and Sleep Medicine, Baylor College of Medicine, Houston, TX, USA. 6. Center for Innovations in Quality, Effectiveness and Safety, Michael E. DeBakey VA Medical Center, Houston, TX, USA. 7. Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, MD, USA. 8. 4DMedical, Woodland Hills, CA, USA. 9. Contributed equally to this work (senior authors). 10. Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA mmccor16@jhmi.edu.
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.
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.
Authors: Meredith C McCormack; Patrick N Breysse; Elizabeth C Matsui; Nadia N Hansel; Roger D Peng; Jean Curtin-Brosnan; D'Ann L Williams; Marsha Wills-Karp; Gregory B Diette Journal: Ann Allergy Asthma Immunol Date: 2011-02-26 Impact factor: 6.347
Authors: W James Gauderman; Robert Urman; Edward Avol; Kiros Berhane; Rob McConnell; Edward Rappaport; Roger Chang; Fred Lurmann; Frank Gilliland Journal: N Engl J Med Date: 2015-03-05 Impact factor: 91.245
Authors: Robert J Kuczmarski; Cynthia L Ogden; Shumei S Guo; Laurence M Grummer-Strawn; Katherine M Flegal; Zuguo Mei; Rong Wei; Lester R Curtin; Alex F Roche; Clifford L Johnson Journal: Vital Health Stat 11 Date: 2002-05
Authors: G H Dong; Z Qian; M-M Liu; D Wang; W-H Ren; Q Fu; J Wang; M Simckes; T F Ferguson; E Trevathan Journal: Int J Obes (Lond) Date: 2012-07-31 Impact factor: 5.095
Authors: F Gilliland; E Avol; R McConnell; K Berhane; W J Gauderman; F W Lurmann; R Urman; R Chang; E B Rappaport; S Howland Journal: Res Rep Health Eff Inst Date: 2017-01
Authors: Valentina Fainardi; Lucrezia Passadore; Marialuisa Labate; Giovanna Pisi; Susanna Esposito Journal: Int J Environ Res Public Health Date: 2022-01-06 Impact factor: 3.390