Slower Rewarming Benefits Bypass Patients

A study has confirmed that spending an extra 10-15 minutes slowly rewarming patients after cardiac bypass surgery reduces the likelihood of cognitive decline after surgery.

Rapid rewarming can lead to a spike in brain temperature, according to the researchers. By allowing patients to return to normal temperatures at a slower rate, doctors can also reduce the possibility of temperatures spiking high enough to harm the brain. Over a seven-year period, the maximum temperatures of patients being rewarmed after undergoing coronary artery bypass surgery at Duke University Hospital (Durham, NC, USA) dropped an average of more than 1.5oC.

However, the researchers say that many surgical teams are unaware of the importance of temperature in affecting the outcomes of bypass surgery. "The reasons why slower rewarming has not become more widespread are numerous, ranging from the inherent resistance to changing long-standing medical practices, to not wanting to spend the additional time in the operating room,” said Hilary Grocott, M.D., who presented the results of the Duke study at the annual meeting of the Society of Cardiovascular Anesthesiologists in Honolulu (HI, USA) in April 2004.

In earlier studies, Duke researchers found that patients who were allowed an additional 10-12 minutes to return to normal body temperature scored almost one-third better on standard tests of cognition six weeks after surgery. Specifically, they found that patients who were returned to normal temperature an average of 0.49oC per minute fared better than those rewarmed at the typical rate of 0.56oC per minute.