For decades the administration of oxygen has been a corner stone in the treatment of various medical emergencies, e.g. acute myocardial infarction. Several arguments support the perioperative use of high oxygen concentrations (80%) for the prevention of surgical site infections. However, effects of oxygen include an increase in systemic vascular resistance, a reduction in heart rate and stroke volume and thus an impairment of the microcirculation, e.g. in the coronary and cerebral vasculature. Adequately powered, prospective, randomized, blinded outcome studies on the effects of hyperoxia in anesthesia and intensive care medicine are scarce. Recent data suggest that hyperoxia may be more harmful than beneficial and may increase morbidity and mortality in surgical and intensive care patients. Also, the current guidelines from the European Resuscitation Council from 2015 address the potentially harmful effects of high oxygen concentrations in various emergency settings. The aim of this article is to give an overview about the physiological and clinical effects of hyperoxia with a focus on its use in perioperative and intensive care medicine.
