Narrator: This is Science Today. Patients who undergo surgery are kept so cool they get hypothermic -- their body temperatures drop four degrees. Anesthesiologist Daniel Sessler of the University of California, San Francisco wondered about the health effects of keeping cool. Sessler studied two groups of surgical patients. One was cooled normally, and the other was kept warm.

Sessler: We observed then the number of wound infections in each group, and found then that the patients that got hypothermic had three times as many infections as the other group. Furthermore, the hypothermic patients stayed in the hospital two days longer, indicating that their wounds were not healing well.

Narrator: Fortunately, Sessler found that a simple heating blanket keeps patients at normal body temperature.

Sessler: We're dealing with something that costs about 30 dollars per patient, which is almost nothing in the scheme of costs for surgery these days, is risk-free and provides an enormous benefit.

Narrator: For Science Today, I'm Steve Tokar.