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

Intrapleural pressure during a forced vital capacity (VC) manoeuvre 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 manoeuvres at varying efforts while airflow, volume, and oesophageal pressure (POES) were measured. Quasi-static 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 manoeuvre. The TGC-corrected curve was obtained by constructing a “maxim...

用力肺活量（forced vital capacity, VC）操作过程中的胸膜腔内压，通常高于产生最大呼气流量所需的压力水平。该过剩压力会压迫肺泡气体（即胸腔气体压缩，thoracic gas compression, TGC），进而导致特定肺容积下测得的用力呼气流量（forced expiratory flows, FEFs）被低估。目前尚不明确胸腔气体压缩是否受性别影响；但鉴于男性拥有更大的肺容积与更强壮的呼吸肌，我们提出研究假设：男性的胸腔气体压缩程度更高。本研究针对11名健康青年男性与12名健康青年女性，检测了其用力肺活量的“用力依赖”区域内的胸腔气体压缩情况。受试者在不同用力程度下完成用力肺活量操作，同步记录气流、肺容积与食管压（oesophageal pressure, POES）。通过准静态呼气放气曲线获取肺弹性回缩压（PLUNG）与肺泡压（即PALV=POES–PLUNG）。从“最大用力”的用力肺活量操作中获取原始最大呼气流量-容积（MEFVraw）曲线。经胸腔气体压缩校正的曲线则通过构建“最大……”得到。