Slowly rewarming bypass patients may reduce risk of brain damage

Most patients undergoing cardiac bypass surgery are placed on heart-lung machines that cool their blood to reduce their bodies’ oxygen needs. Now researchers have found that taking an extra 10 to 15 minutes to slowly rewarm patients at the end of their surgery reduces brain overheating, lowering the risk of brain damage and memory loss.

Researchers from Duke University Medical Center in Durham, N.C., showed several years ago that patients given an extra 10 to 12 minutes to bring their body temperatures back up scored nearly one-third better on standard cognition tests six weeks after surgery.

In a new study, the researchers reported that by changing long-standing rewarming practices in recent years, Duke surgical teams were able to prevent potentially damaging overheating. The analysis of 6,334 Duke patients who underwent bypass surgery from 1993 to 2000 found that, because of the change, maximum body temperatures dropped an average of 2.7 degrees Fahrenheit.

“Even a half- to one degree of temperature can aggravate a brain that is injured,” said lead study author Dr. Hilary Grocott, a cardiac anesthesiologist. He said that despite the increased awareness of the consequences of having brain temperatures spike as warmed blood is pumped into the heart and then to the brain, many hospitals continue to raise body temperatures the standard way.

Grocott presented the findings last Monday at the annual scientific sessions of the Society of Cardiovascular Anesthesiologists in Honolulu.

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Jane E. Allen