Thoracic gas compression during forced expiration is greater in men than women

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Gideon, EA
Cross, TJ
Cayo, BE
Betts, AW
Merrell, DS
Coriell, CL
Hays, LE
Duke, JW
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Intrapleural pressure during a forced vital capacity (VC) maneuver is often in excess of that required to generate maximal expiratory airflow. This excess pressure compresses alveolar gas (i.e., thoracic gas compression [TGC]), resulting in underestimated forced expiratory flows (FEFs) at a given lung volume. It is unknown if TGC is influenced by sex; however, because men have larger lungs and stronger respiratory muscles, we hypothesized that men would have greater TGC. We examined TGC across the “effort-dependent” region of VC in healthy young men (n = 11) and women (n = 12). Subjects performed VC maneuvers at varying efforts while airflow, volume, and esophageal pressure (POES) were measured. Quasistatic expiratory deflation curves were used to obtain lung recoil (PLUNG) and alveolar pressures (i.e., PALV = POES–PLUNG). The raw maximal expiratory flow–volume (MEFVraw) curve was obtained from the “maximum effort” VC maneuver. The TGC-corrected curve was obtained by constructing a “maximal perimeter” curve from all VC efforts (MEFVcorr). TGC was examined via differences between curves in FEFs (∆FEF), area under the expiratory curves (∆AEX), and estimated compressed gas volume (∆VGC) across the VC range. Men displayed greater total ∆AEX (5.4 ± 2.0 vs. 2.0 ± 1.5 L2·s−1; p <.001). ∆FEF was greater in men at 25% of exhaled volume only (p <.05), whereas ∆VGC was systematically greater in men across the entire VC (main effect; p <.05). PALV was also greater in men throughout forced expiration (p <.01). Taken together, these findings demonstrate that men display more TGC, occurring early in forced expiration, likely due to greater expiratory pressures throughout the forced VC maneuver.

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Physiological Reports

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© 2020 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Clinical sciences

Medical physiology

alveolar pressure

area under the curve

flow volume loop

lung recoil pressure

respiratory mechanics

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Gideon, EA; Cross, TJ; Cayo, BE; Betts, AW; Merrell, DS; Coriell, CL; Hays, LE; Duke, JW, Thoracic gas compression during forced expiration is greater in men than women, Physiological Reports, 2020, 8 (6), pp. e14404-