Critical Care volume 25 , Article number: Cite this article. Metrics details. Oxygen O 2 toxicity remains a concern, particularly to the lung. This is mainly related to excessive production of reactive oxygen species ROS. Supplemental O 2 , i. Here, we review the pathophysiology of O 2 toxicity and the potential harms of supplemental O 2 in various ICU conditions.
Since even moderately supra-physiological PaO 2 may be associated with deleterious side effects, it seems advisable at present to titrate O 2 to maintain PaO 2 within the normal range, avoiding both hypoxaemia and excess hyperoxaemia.
It is vital for aerobic respiration within the mitochondria, yet mitochondrial respiration also forms reactive oxygen species ROS [ 5 ], production of which relates to O 2 concentration [ 6 , 7 , 8 ].
Consequently, O 2 toxicity, especially pulmonary, is a matter of concern [ 13 , 14 , 15 ], and optimal dosing remains unclear in critical care. This review discusses potential harms of O 2 in various underlying critical illnesses.
Figure 1 summarises the possible dangers of hyperoxia, highlighting pathophysiological mechanisms and their impact on specific disease conditions. Potential harm of hyperoxia. Nevertheless, it is noteworthy that PO 2 levels as low as 0. Oxygen generally exists as di-atomic molecule O 2 ; its two atoms bond to each other through single bonds leaving two unpaired electrons.
