Oxygen (O2) toxicity remains a concern, particularly to the lung. This is mainly related to excessive production of reactive oxygen species (ROS). Supplemental O2, i.e. inspiratory O2 concentrations (FIO2) > 0.21 may cause hyperoxaemia (i.e. arterial (a) PO2 > 100 mmHg) and, subsequently, hyperoxia (increased tissue O2 concentration), thereby enhancing ROS formation. Here, we review the pathophysiology of O2 toxicity and the potential harms of supplemental O2 in various ICU conditions. The current evidence base suggests that PaO2 > 300 mmHg (40 kPa) should be avoided, but it remains uncertain whether there is an “optimal level” which may vary for given clinical conditions. Since even moderately supra-physiological PaO2 may be associated with deleterious side effects, it seems advisable at present to titrate O2 to maintain PaO2 within the normal range, avoiding both hypoxaemia and excess hyperoxaemia.

中文翻译：

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高氧的危险

氧气 (O2) 毒性仍然是一个令人担忧的问题，特别是对于肺部。这主要与活性氧（ROS）产生过多有关。补充 O2，即吸气 O2 浓度 (FIO2) > 0.21 可能会导致高氧血症（即动脉 (a) PO2 > 100 mmHg），随后导致高氧血症（组织 O2 浓度增加），从而增强 ROS 形成。在这里，我们回顾了氧气毒性的病理生理学以及在各种 ICU 条件下补充氧气的潜在危害。目前的证据基础表明，应避免 PaO2 > 300 mmHg (40 kPa)，但仍不确定是否存在“最佳水平”，该水平可能因特定的临床条件而异。由于即使适度超生理 PaO2 也可能与有害副作用相关，因此目前建议滴定 O2 以将 PaO2 维持在正常范围内，避免低氧血症和过度高氧血症。