Antioxidant therapy in critical care medicine

Antioxidant therapies are currently undergoing clinical trials to determine their benefit in a number of diseases seen in the critical care unit. It is particularly likely that their use will become standard therapy in a number of situations in which there is reperfusion injury following an ischemic episode. During the lag time from the conception of antioxidant interventions to their introduction into clinical practice, our understanding of how oxidant injuries are mediated has changed considerably. This understanding has allowed the development of more rational approaches to antioxidant therapy while exposing the limitations of some of the approaches currently being evaluated in a clinical setting. In addition, some existing therapeutic agents have previously unrecognized antioxidant and pro-oxidant effects. An inherent requirement of an effective antioxidant therapy is that such therapy is effective against the radicals being generated, and that sufficient quantities of the antioxidants used reach all sites of radical generation in time to limit tissue injury. Recent observations suggest that few, if any, of the currently known individual antioxidants can adequately meet these goals. However, combination therapy, or the development of synthetic compounds that can combine the properties of current antioxidants, may come close.