Researchers looked at 91 patients, average age 79, and found that 45 percent of them experienced a sudden change in level of consciousness, inattention and disturbed mental function -- called early delirium -- in the recovery room.
In many cases, delirium persisted after patients were moved to hospital wards. Overall, about three-quarters of all cases of delirium that occurred in the hospital after surgery began in the recovery room.
Patients with early delirium showed significant declines in mental function, even after the researchers accounted for other factors, including length of surgery.
All of the patients in the study lived independently before their surgery. The study found that 39 percent of patients with early, persistent delirium were discharged from the hospital to a nursing home or other facility instead of to their home, compared with 3 percent of those without early delirium.
Among patients who had early delirium but were normal on the day after surgery, 26 percent were discharged to an institution, according to the study, which was published in the August issue of the journal Anesthesia & Analgesia.
The findings show that delirium is a "common but not universal" problem for elderly patients who have surgery, said Dr. Karin Neufeld, of Johns Hopkins University, and colleagues. They said 55 percent of patients did not have delirium in the recovery room, and 85 percent of them remained normal throughout their hospital stay.
The findings suggest, however, that even brief periods of delirium can have lasting effects in seniors, according to a journal news release. The researchers said many cases of delirium in this study would have been missed if monitoring had started the day after surgery, rather than in the recovery room.
Although the researchers found an association among surgery, early delirium in seniors and being discharged to an institution instead of home, the study did not establish a cause-and-effect relationship.
The researchers said further studies are needed to determine the rate and impact of early delirium after anesthesia and surgery.
The U.S. National Institute on Aging has more about seniors and surgery.