Single Center Reports Major Fall in Cerebral Hyperthermia After Cardiac Surgery

Cerebral temperatures exceeding 38 degrees Celsius during the rewarming phase of hypothermic cardiac surgery have been linked to adverse cognitive effects. Now, researchers from Duke University report that since instituting slower rewarming protocols the rates of cerebral hyperthermia have dropped dramatically.

Four years ago at the annual meeting of the Society of Cardiovascular Anesthesiologists, researchers from the Durham, North Carolina-based institution showed attendees how adding an extra 10 minutes to the rewarming phase could significantly improve cognitive outcomes at 6 weeks (see Reuters Health report May 12, 2000).

This week, the research team, led by Dr. Hilary Grocott, returned to the meeting, held this year in Honolulu, to present trends in cerebral hyperthermia at their center between January 1993 and June 2000. The study cohort consisted of all 6334 adult patients who underwent hypothermic cardiac surgery during that period.

Between January 1993 and December 1996, the maximum nasopharyngeal temperature during rewarming dropped by about 0.34 degrees Celsius per year. The temperature continued to fall during the rest of the study period, but at a slower rate — 0.10 degrees Celsius per year.

Of the first 10% of patients who underwent surgery during the study period, nearly 83% had maximum temperatures greater than 38 degrees Celsius. In contrast, among the most recent 10% of patients, only 2.9% had maximum temperatures that reached this level (p < 0.0001). “The incidence of cerebral hyperthermia can be reduced” by aiming for lower peak temperatures and slowing the rewarming rate, Dr. Grocott told Reuters Health. “We did it at our institution and it can be done elsewhere.” “The most important point is to limit the peak temperature, which will have an impact on the rewarming rate,” Dr. Grocott emphasized. “If I had to set a temperature goal, I would say try to keep it at or below 37 degrees Celsius.”