CHICAGO, Feb. 6 (Xinhua) -- After studying more than 1,200 older surgical patients, U.S. researchers found that meticulously monitoring brain activity and then taking care to minimize levels of anesthesia during surgery had no significant effect on the occurrence of delirium, but are linked to lower 30-day mortality.
Of the 1,232 patients in the study by researchers at Washington University School of Medicine, half were randomly assigned to very close monitoring of the brain's electrical activity, as measured by electroencephalogram (EEG) during surgery; and the rest were given usual care during their operations.
The researchers found that 26 percent of the closely monitored group still experienced delirium in the first five days after surgery. By comparison, 23 percent of those in the group that did not receive such close monitoring of brain activity developed delirium during the same time period. That difference was not statistically significant.
But surprisingly, there were fewer deaths among patients whose brain activity was monitored closely and anesthesia levels adjusted. In the monitored group, four of 614 patients or fewer than one percent died in the month after surgery. Among the 618 patients who did not receive such close brain monitoring, 19 or more than 3 percent died within 30 days of their surgeries. That difference is statistically significant.
"When older adults have major surgery, one in four of them experiences delirium. That's a large number," said principal investigator Michael S. Avidan, a professor of anesthesiology at the university. "I believe we should monitor the brain of every single patient during general anesthesia, just as we routinely monitor heart and lung function."
The researchers defined major surgery as procedures requiring at least two hours of general anesthesia and at least two days in the hospital following the operation.
Delirium, described as a state of confusion or agitation, is common after surgery. About 25 percent of older surgery patients experience postoperative delirium.
The findings were published Tuesday in the Journal of the American Medical Association (JAMA).
