Supplemental oxygen administration was first noted to correct signs and symptoms of hypoxic respiratory failure more than a century ago.1,2 Since that time, oxygen has become one of the most widely administered therapeutic interventions in medicine. The prevention or reversal of hypoxia can be lifesaving, but excessive oxygen supplementation and resulting hyperoxia promotes resorption atelectasis and free radical formation leading to oxidative damage to tissues, endothelial dysfunction, and other deleterious effects.3