Effects of Hyperoxia on Prognosis after Cardiac Arrest

Abstract

Oxygen toxicity is currently suspected when used in patients resuscitated from a cardiac arrest. Although essential during cardio-pulmonary resuscitation, oxygen provided in larger amounts might increase tissue damages provoked by this global ischemia-reperfusion syndrome. Experimentally, exposition of animals to hyperoxia during and after cardiopulmonary resuscitation increases oxidative stress and may worsen prognosis, mostly because it increases brain damages. However, it is unclear if these experimental observations are transposable to the clinical scene: in humans, results from several retrospective studies suggest a deleterious effect of hyperoxia in cardiac arrest, but most of these studies suffer from several methodological biases and their conclusion have been partly contradicted in subsequent studies. While waiting for the results coming from ongoing trials, recent international guidelines recommend titrating the oxygen treatment as soon as possible during resuscitation and after return of spontaneous circulation in order to maintain an arterial saturation between 94% and 98%.