Abstract: Severe pneumonia is an important cause of acute respiratory failure，and its core pathology is hypoxemia. This article elaborates on the criteria for hypoxemia，the conditions for the body to maintain normal oxygen partial pressure，the mechanism of hypoxemia in severe pneumonia，and the compensatory manifestations of the body.

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摘要： 重症肺炎是急性呼吸衰竭的重要原因，其病理核心为低氧血症。文章从低氧血症的定义、机体维持正常氧分压的条件、重症肺炎发生低氧血症的机制以及机体的代偿反应等方面做了阐述。

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