How Gender Bends Anesthesia

A project led by researchers designed to look at the effectiveness of monitor used in surgery has instead uncovered a startling find -- women wake up faster than men after surgery.

The study, published this month in the medical journal Anesthesiology, is the first of its kind and expected to lead to further research.

Scientists from Duke, the University of North Carolina at Chapel Hill, Harvard and Emory collected surgery data, expecting only to report on a device that measures brain activity. The bispectral index monitor is used to help keep a patient asleep just deep enough to undergo surgery but still able to awaken as quickly as possible following an operation.

To their surprise, the researchers found that women, on average, took about seven minutes to regain consciousness after anesthesia was stopped. Men needed just over 11 minutes.

"We still don't know exactly what's going on," said Tom Gan, associate professor of anesthesiology at Duke University Medical Center and lead author of the study.

The findings were consistent at all four hospitals where data was collected. Gan speculates that women may metabolize the drug quicker, or could simply be less sensitive to them.

The study was funded by Aspect Medical Systems, the Boston company that makes the bispectral index monitor. The company is hoping to use the study's primary findings -- that patients wake up more quickly with the new monitor than without it -- to help market the device.