Oxygen therapy is one of the most ubiquitously applied therapies in modern medicine. Clinicians usually react rapidly to declining oxygen saturations. Although this response is appropriate in the setting of hypoxia, there are many circumstances in which excess oxygen is indiscriminately administered for extended periods.

Medicine has recently experienced a shift from “more is better” to “less is more” as more has been learned about the ability of the human body to adapt to extreme physiological conditions and about the inappropriate use of various therapies. Examples include hemoglobin thresholds and carbon dioxide levels. Attention in recent years has focused on the potential harms associated with excess oxygen therapy.

Oxygen toxicity was first recognized clinically in an outbreak of retinal hyperplasia in premature infants leading to childhood blindness in the 1940s. Reports of oxygen pneumonitis were first described in the 1970s when autopsy findings demonstrated lung injury across patients who were exposed to concentrations of oxygen greater than 0.60 for at least 3 days of mechanical ventilation. In critical care, an early focus on harms of hyperoxia was attenuated after recognition of ventilator–associated lung injury, which shifted the cause from hyperoxia to injurious ventilation.

氧气疗法是现代医学中应用最广泛的疗法之一。临床医生通常会对氧饱和度下降做出快速反应。尽管这种反应在缺氧的情况下是适当的，但在许多情况下，会长时间不加选择地给予过量氧气。

随着人们对人体适应极端生理条件的能力以及对各种疗法的不当使用的了解越来越多，医学最近经历了从“越多越好”到“越少越多”的转变。例子包括血红蛋白阈值和二氧化碳水平。近年来，注意力集中在与过量氧气疗法有关的潜在危害上。

在1940年代早产儿发生视网膜增生并导致儿童失明的情况下，首先在临床上认识到氧中毒。氧气肺炎的报道最早是在1970年代描述的，当时的尸检结果表明，暴露于氧气浓度大于0.60且进行了至少3天的机械通气的患者，肺部受到了损伤。在重症监护中，认识到呼吸机相关的肺损伤后，对高氧血症危害的早期关注就减弱了，这将病因从高氧血症转移到了有害的通气。