NEW YORK, May 20 (Reuters Health) -- Researchers have discovered that women tend to wake up almost twice as fast as men following general anesthesia, suggesting that women may be less sensitive to these drugs, and may need higher doses during surgery.
The findings fit with reports that three times more women than men have complained of being awake during surgery, note lead author Dr. Tong J.Gan of Duke University Medical Center in Durham, North Carolina, and multicenter colleagues.
"These findings may explain the increased reported incidence of awareness (during surgery) in women... and support the need to include gender as a variable in... studies of anesthetic drugs," the research team suggests.
The study, which included 96 men and 178 women scheduled for general, gynecologic, urologic, ear, nose or throat, or orthopedic surgery, was originally designed to measure the effects of a device that interprets brain wave patterns when a patient is unconscious.
Each patient received a standard dose of anesthesia plus a painkiller. Typically, doses of anesthesia are based on body size, which means that women generally receive less than men.
Researchers monitored each patient's level of consciousness and how quickly they awoke once the drug was stopped. Results showed that female patients woke up after an average of 7 minutes and men after an average of 11 minutes.
However, the investigators could not explain why women may respond differently to anesthesia than men.
"It could be that women are less sensitive to these anesthetics than men, or that they metabolize them faster. Or both," suggests Gan in a statement issued by Duke University Medical Center.
Their study, which is published in the May issue of the journal Anesthesiology, notes that women might respond differently than men to other pharmaceutical agents.
"We really need to have a hard look at gender differences in sensitivity to anesthetics, and follow up with more research," Gan said in the University statement.
SOURCE: Anesthesiology 1999;90:1283-1287.
