You're Never Too Cool for Pneumonia

One of the crucial interventions to undertake after a person suffers cardiac arrest is therapeutic hypothermia. This intervention cools the body temperature (by a few degrees Centigrade) in order to minimize damage to then brain that might have occurred during the period of time the person was deprived of oxygen and after circulation has been restored. 

There are several means to achieve a lowered body temperature and usually include either the insertion of a cooling catheter in a major vein or a special cooling blanket. 

One of the caveats to therapeutic hypothermia is that it increases the risk of infection. A recent systematic review and meta-analysis published in Critical Care Medicine, tries to asses the magnitude of this risk. 

Pooling the results of prior research, as was done in this paper, revealed that therapeutic hypothermia increases the risk of pneumonia and sepsis. This is not a surprising finding given the impact cold temperatures can  have on the immune system. Specifically, hypothermia blunts the ability of cells to employ specific cytokines thus rendering the individual in a net state of immunosupression. 

This finding illustrates the delicate balance physicians must strike in order to optimally treat a patient, continually weighing risks versus benefits. In the end, therapeutic hypothermia--for those who need it--confers too high of a  benefit to be jettisoned secondary to a heightened risk of infection.