[Well-meant oxygen administration with harmful effects]

For more than hundred years oxygen has been administered to patients for a variety of indications: first and foremost to treat, and later to prevent, hypoxemia. Some years after the first exhilarating reports, it became apparent that hyperoxemia may have harmful sequelae. The pathophysiological mechanism has been determined: vasoconstiction of coronary, cerebral and systemic arteries. And additionally the formation of reactive oxygen species, resulting in cellular damage and ultimately cell death. In a variety of medical emergencies the detrimental clinical effects of hyperoxemia have been demonstrated: increased mortality and more organ dysfunction. And recently it was found the latter also applies to patients undergoing (elective) surgery. It might therefore be concluded that hyperoxemia is justifiable for short periods of time to prevent hypoxemia (i.e. endotracheal intubation), but in all other situations normoxemia should be the target.