Why COVID-19 Silent Hypoxemia Is Baffling to Physicians
Why COVID-19 Silent Hypoxemia Is Baffling to Physicians
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DOI：
10.1164/rccm.202006-2157cp
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发表时间：
2020-08-01
影响因子：
24.7
通讯作者：
Jubran, Amal
中科院分区：
文献类型：
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作者：
Tobin, Martin J.;Laghi, Franco;Jubran, Amal
患有冠状病毒病（COVID-19）的患者被描述为表现出与生命不相容的氧气水平而没有呼吸困难。这种配对被称为快乐缺氧，但更准确地说是无声低氧血症，这对医生来说尤其令人困惑，并被认为是对基本生物学的挑战。这种组合吸引了媒体的广泛报道，但尚未在医学期刊上讨论。冠状病毒可能对涉及对氧的化学敏感性的受体具有特异性作用，但完善的病理生理机制可以解释大多数（如果不是全部）无症状低氧血症病例。这些机制包括呼吸困难和呼吸中枢对低氧水平的反应方式、普遍存在的二氧化碳张力（Pa-CO2）减弱大脑对低氧的反应方式、疾病和年龄对呼吸控制的影响、低氧饱和度下脉搏血氧测定的不准确性以及氧解离曲线中温度诱导的偏移。在不了解这些机制的情况下，照顾没有呼吸困难的低氧血症患者的医生正在黑暗中操作，将脆弱的COVID-19患者置于相当大的风险之中。总而言之，从长期确立的呼吸生理学原理来看，医生们感到困惑的COVID-19特征变得不那么奇怪了;如果人们期待已久的第二波疫情出现，对这些机制的理解将有助于加强对患者的护理。
Patients with coronavirus disease (COVID-19) are described as exhibiting oxygen levels incompatible with life without dyspnea. The pairing-dubbed happy hypoxia but more precisely termed silent hypoxemia-is especially bewildering to physicians and is considered as defying basic biology. This combination has attracted extensive coverage in media but has not been discussed in medical journals. It is possible that coronavirus has an idiosyncratic action on receptors involved in chemosensitivity to oxygen, but well-established pathophysiological mechanisms can account for most, if not all, cases of silent hypoxemia. These mechanisms include the way dyspnea and the respiratory centers respond to low levels of oxygen, the way the prevailing carbon dioxide tension (Pa-CO2) blunts the brain's response to hypoxia, effects of disease and age on control of breathing, inaccuracy of pulse oximetry at low oxygen saturations, and temperature-induced shifts in the oxygen dissociation curve. Without knowledge of these mechanisms, physicians caring for patients with hypoxemia free of dyspnea are operating in the dark, placing vulnerable patients with COVID-19 at considerable risk. In conclusion, features of COVID-19 that physicians find baffling become less strange when viewed in light of long-established principles of respiratory physiology; an understanding of these mechanisms will enhance patient care if the much-anticipated second wave emerges.