What is oxygen toxicity in mechanical ventilation?

Updated: Sep 15, 2020
  • Author: Christopher D Jackson, MD; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Oxygen toxicity is a function of increased FIO2 and its duration of use. Oxygen toxicity is due to the production of oxygen free radicals, such as superoxide anion, hydroxyl radical, and hydrogen peroxide. Oxygen toxicity can cause a variety of complications ranging from mild tracheobronchitis and absorptive atelectasis to diffuse alveolar damage that is indistinguishable from ARDS.

No consensus has been established for the level of FIO2 required to cause oxygen toxicity, but this complication has been reported in patients given a maintenance FIO2 of 50% or greater. The clinician is encouraged to use the lowest FIO2 that accomplishes satisfactory oxygenation.

The medical literature suggests that the clinician should attempt to attain an FIO2 of 60% or less within the first 24 hours of mechanical ventilation. If necessary, PEEP should be considered a means to improve oxygenation while a safe FIO2 is maintained. When PEEP is effective and not contraindicated because of hemodynamics or other reasons, the patient can usually be oxygenated while the risks of oxygen toxicity are limited.

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