McCulloch Paul F, Gebhart B W, Schroer J A
Department of Physiology, College of Graduate Studies, Midwestern University, Downers Grove, IL, United States.
Chicago College of Osteopathic Medicine, Midwestern University, Downers Grove, IL, United States.
Front Physiol. 2021 Sep 29;12:731633. doi: 10.3389/fphys.2021.731633. eCollection 2021.
During breath holding after face immersion there develops an urge to breathe. The point that would initiate the termination of the breath hold, the "physiological breaking point," is thought to be primarily due to changes in blood gases. However, we theorized that other factors, such as lung volume, also contributes significantly to terminating breath holds during face immersion. Accordingly, nine naïve subjects (controls) and seven underwater hockey players (divers) voluntarily initiated face immersions in room temperature water at Total Lung Capacity (TLC) and Functional Residual Capacity (FRC) after pre-breathing air, 100% O, 15% O / 85% N, or 5% CO / 95% O. Heart rate (HR), arterial blood pressure (BP), end-tidal CO (etCO), and breath hold durations (BHD) were monitored during all face immersions. The decrease in HR and increase in BP were not significantly different at the two lung volumes, although the increase in BP was usually greater at FRC. BHD was significantly longer at TLC (54 ± 2 s) than at FRC (30 ± 2 s). Also, with each pre-breathed gas BHD was always longer at TLC. We found no consistent etCO at which the breath holding terminated. BDHs were significantly longer in divers than in controls. We suggest that during breath holding with face immersion high lung volume acts directly within the brainstem to actively delay the attainment of the physiological breaking point, rather than acting indirectly as a sink to produce a slower build-up of PCO.
面部浸入水中后屏气时会产生呼吸冲动。引发屏气终止的点，即“生理突破点”，被认为主要是由于血气变化所致。然而，我们推测其他因素，如肺容量，在面部浸入过程中对终止屏气也有显著作用。因此，9名未经训练的受试者（对照组）和7名水下曲棍球运动员（潜水员）在预呼吸空气、100%氧气、15%氧气/85%氮气或5%二氧化碳/95%氧气后，于总肺容量（TLC）和功能残气量（FRC）状态下自愿在室温水中进行面部浸入。在所有面部浸入过程中监测心率（HR）、动脉血压（BP）、呼气末二氧化碳（etCO）和屏气持续时间（BHD）。在两种肺容量状态下，HR的下降和BP的升高没有显著差异，尽管在FRC状态下BP的升高通常更大。TLC时的BHD（54±2秒）显著长于FRC时（30±2秒）。此外，对于每种预呼吸气体，TLC时的BHD总是更长。我们没有发现屏气终止时一致的etCO值。潜水员的BHD显著长于对照组。我们认为，在面部浸入屏气过程中，高肺容量直接作用于脑干，积极延迟生理突破点的达到，而不是间接作为一个汇来使PCO2的积累变慢。
