Tetzlaff Kay, Lemaitre Frederic, Burgstahler Christof, Luetkens Julian A, Eichhorn Lars
Department of Sports Medicine, University Hospital of Tübingen, Tübingen, Germany.
Faculte des Sciences du Sport et de l'Education Physique, Universite de Rouen, Rouen, France.
Front Physiol. 2021 Jul 9;12:710429. doi: 10.3389/fphys.2021.710429. eCollection 2021.
Breath-hold diving involves environmental challenges, such as water immersion, hydrostatic pressure, and asphyxia, that put the respiratory system under stress. While training and inherent individual factors may increase tolerance to these challenges, the limits of human respiratory physiology will be reached quickly during deep breath-hold dives. Nonetheless, world records in deep breath-hold diving of more than 214 m of seawater have considerably exceeded predictions from human physiology. Investigations of elite breath-hold divers and their achievements revised our understanding of possible physiological adaptations in humans and revealed techniques such as glossopharyngeal breathing as being essential to achieve extremes in breath-hold diving performance. These techniques allow elite athletes to increase total lung capacity and minimize residual volume, thereby reducing thoracic squeeze. However, the inability of human lungs to collapse early during descent enables respiratory gas exchange to continue at greater depths, forcing nitrogen (N) out of the alveolar space to dissolve in body tissues. This will increase risk of N narcosis and decompression stress. Clinical cases of stroke-like syndromes after single deep breath-hold dives point to possible mechanisms of decompression stress, caused by N entering the vasculature upon ascent from these deep dives. Mechanisms of neurological injury and inert gas narcosis during deep breath-hold dives are still incompletely understood. This review addresses possible hypotheses and elucidates factors that may contribute to pathophysiology of deep freediving accidents. Awareness of the unique challenges to pulmonary physiology at depth is paramount to assess medical risks of deep breath-hold diving.
屏气潜水会带来一些环境挑战，比如水浸、静水压力和窒息，这些会给呼吸系统造成压力。虽然训练和个体的内在因素可能会增加对这些挑战的耐受性，但在深度屏气潜水中，人体呼吸生理的极限会很快被突破。尽管如此，超过214米海水深度的屏气潜水世界纪录已大大超出了人体生理学的预测。对精英屏气潜水员及其成就的研究修正了我们对人类可能的生理适应的理解，并揭示了诸如舌咽呼吸等技术对于在屏气潜水表现中达到极致至关重要。这些技术使精英运动员能够增加肺总容量并最小化残气量，从而减少胸廓挤压。然而，人类肺部在下降过程中不能过早塌陷，这使得呼吸气体交换在更深的深度仍能继续，迫使氮气从肺泡空间排出并溶解在身体组织中。这将增加氮麻醉和减压应激的风险。单次深度屏气潜水后出现类似中风综合征的临床病例指出了减压应激的可能机制，这是由氮气在从这些深度潜水上升时进入血管系统所导致的。深度屏气潜水中神经损伤和惰性气体麻醉的机制仍未完全被理解。这篇综述探讨了可能的假说，并阐明了可能导致深度自由潜水事故病理生理学的因素。认识到深度对肺生理的独特挑战对于评估深度屏气潜水的医疗风险至关重要。
