Oxygen and resuscitation: beyond the myth.

Abstract

Perhaps nothing in medicine is more steeped in myth than oxygen. From its initial success in treating pulmonary tuberculosis to its failure in treating cholera, oxygen has fallen in and out of style. Only gradually did oxygen gain favor as a treatment for respiratory distress with even the likes of Osler doubting its effectiveness. But by the early 1900s, treatment of patients with pulmonary parenchymal disease was so convincing that a lack of appreciation for oxygen’s potentially harmful effects led to its eventual widespread acceptance.a We started using oxygen for resuscitation because it seemed like a good idea. Now we use it because we always have. The use of 100% oxygen in resuscitation is intuitively appealing. Maximizing the gradient driving oxygen into hypoxic cells may speed recovery. However, it is well known that long-term exposure to 100% oxygen is toxic. The proponents of oxygen therapy argue that toxicity simply does not occur during the short period of resuscitation. Although this may be true with respect to effects like fibrosis and pulmonary edema, the real concern is for reperfusion injury. In reperfusion injury, hypoxic cells appear to undergo metabolic changes that prime them to create free radicals when oxygen is reintroduced.1–3 Experimental resuscitation with 100% oxygen has been associated with a variety of concerning physiologic changes when compared with room air resuscitation. They include increased generation of oxygen radicals,4 decreased central nervous system sodium-potassium ATPase function,5 and decreased dopamine metabolism.6 Although there is no data on the safety or danger of short-term exposure to 100% oxygen, the reperfusion injury literature suggests that resuscitation from hypoperfusion states (ie, sudden cardiac arrest, hypovolemic, or distributive shock) is precisely the time when oxygen toxicity from free radicals is likely to occur. Given the potential harm of supplemental … Address correspondence to William Lefkowitz, MD, Department of Pediatrics, Room C-1066, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd, Bethesda, MD 20814. E-mail: wlefkowitz{at}usuhs.mil