Hyperoxemia--too much of a good thing?

While avoiding hypoxemia has long been a goal of critical care practitioners, less attention has been paid to the potential for excessive oxygenation. Interest has mounted recently in understanding the clinical effects of hyperoxemia during critical illness, in particular its impact following cardiac arrest. In this issue of Critical Care, Dell'Anna and colleagues review available animal and human data evaluating the impact of hyperoxemia after cardiac arrest. They conclude that while hyperoxemia during cardiopulmonary resuscitation is probably desirable, it should probably be avoided during post-resuscitation care. These conclusions are in line with two broader themes in contemporary critical care: that less may be more; and that it is time to look beyond simply preventing short-term mortality towards longer-term outcomes.