Sequential diving by wild marine mammals results in a lifetime of rapid physiological transitions between lung collapse-reinflation, bradycardia-tachycardia, vasoconstriction-vasodilation, and oxygen store depletion-restoration. The result is a cycle of normoxia and hypoxia in which blood oxygen partial pressures can decline to <20–30 mmHg during a dive, a level considered injurious to oxygen-dependent human tissues (i.e., brain, heart). Safeguards in the form of enhanced on-board oxygen stores, selective oxygen transport, and unique tissue buffering capacities enable marine-adapted mammals to maintain physiological homeostasis and energy metabolism even when breathing and pulmonary gas exchange cease. This stands in stark contrast to the vulnerability of oxygen-sensitive tissues in humans that may undergo irreversible damage within minutes of ischemia and tissue hypoxia. Recently, these differences in protection against hypoxic injury have become evident in the systemic, multi-organ physiological failure during COVID-19 infection in humans. Prolonged recoveries in some patients have led to delays in the return to normal exercise levels and cognitive function even months later. Rather than a single solution to this problem, we find that marine mammals rely on a unique, integrative assemblage of protections to avoid the deleterious impacts of hypoxia on tissues. Built across evolutionary time, these solutions provide a natural template for identifying the potential for tissue damage when oxygen is lacking, and for guiding management decisions to support oxygen-deprived tissues in other mammalian species, including humans, challenged by hypoxia.

野生海洋哺乳动物的连续潜水导致肺塌陷-再充气、心动过缓-心动过速、血管收缩-血管舒张和氧气储存耗尽-恢复之间的一生快速生理转变。结果是一个常氧和缺氧循环，在潜水过程中，血氧分压会下降到 <20-30 mmHg，这个水平被认为对依赖氧气的人体组织（即大脑、心脏）有害。增强的机载氧气储存、选择性氧气运输和独特的组织缓冲能力等形式的保障措施使适应海洋的哺乳动物即使在呼吸和肺气体交换停止时也能维持生理稳态和能量代谢。这与人类氧敏感组织的脆弱性形成鲜明对比，这些组织可能在缺血和组织缺氧的几分钟内遭受不可逆的损害。最近，在人类感染 COVID-19 期间，系统性、多器官生理衰竭中，这些针对缺氧损伤的保护差异变得明显。一些患者的长期康复导致甚至几个月后恢复正常运动水平和认知功能的延迟。我们发现海洋哺乳动物不是通过单一的解决方案来解决这个问题，而是依靠独特的、综合的保护措施来避免缺氧对组织的有害影响。这些解决方案跨越进化时间，提供了一个自然模板，用于识别缺氧时组织损伤的可能性，