Timing of Surgery Can Contribute to Complications

THURSDAY, Aug. 3 (HealthDay News) -- Here''s some news that will make you think twice about what time of day you go under the knife.

Unexpected adverse events related to anesthesia were more likely to happen when surgery started in the late afternoon than when it started in the morning, Duke researchers report.

The problems, however, were mostly minor ones.

"We''re mainly dealing with an increase in nausea and pain interventions," said Dr. James S. Hicks, an associate professor of anesthesiology and perioperative medicine at Oregon Health and Science University in Portland, and chairman of the American Society of Anesthesiologists Committee on Quality Management and Departmental Administration. "It''s subtle data, but we never want to rest on our laurels," Hicks added.

Although the study didn''t specifically look at reasons for this, anything from doctor caseload and fatigue to patients'' circadian rhythms and problematic communication could be responsible. The good news is that most of these issues can be addressed.

"This is a great piece of work that begins to get at what is really making the difference here," said Dr. David Lubarsky, chairman of anesthesiology at the University of Miami Miller School of Medicine. "It directs hospitals to look at these things."

Previous research has linked impaired human performance with lack of sleep, long work hours, and disruption in circadian rhythms.

Fatigue is thought to be a bigger contributor to transportation accidents than drugs and alcohol combined. But specific research into time of day and performance in medicine is limited.

The authors of this study, which was published in the August issue of Quality & Safety in Health Care, hypothesized that the time of day surgery took place would influence the number of adverse events related to anesthesia.

The researchers analyzed more than 90,000 surgeries performed at Duke Hospital from 2000 to 2004, and categorized them according to type or severity of the adverse event. The categories were then cross-referenced with the time of the surgery.

Adverse events were most common for operations starting between 3 p.m. and 4 p.m., as compared with 7 a.m. The lowest probability of having an adverse event (1 percent) was at 9 a.m. and the highest (4.2 percent) at 4 p.m.

"That''s a pretty big increase," said study author Melanie Wright, an assistant professor of anesthesiology at Duke University Medical Center.

The two most common types of problems were pain management and postoperative nausea and vomiting.

Patients also experienced more "administrative delays," such as waiting for test results, doctors running late and rooms not ready, during the late afternoon. This could also contribute to adverse events.

Any number of factors may be responsible for the differences.

"Patients might be more susceptible to pain in the afternoon," Wright said.

The late-afternoon period also coincides with natural lows in the circadian rhythm, or the body''s internal clock. Anesthesia care teams usually change at about 7 in the morning, and again between 4 p.m. and 6 p.m. This could be colliding with circadian low points and end-of-day fatigue.

A new concept called "chronobiology" might even be at fault. "It is possible that people react to drugs differently at different times of the day," said Dr. David Birnbach, director of the University of Miami''s Center for Patient Safety. "People are now looking at the effect on drugs of circadian rhythms, how long since the last cup of coffee, how many visitors, was it a quiet time or busy time," he added.

There could also be a combination of doctor fatigue along with high caseloads and communication problems.

"We have fewer guys watching more cases. We''ve got tired folks handing off patients, and there''s lots of room for communication problems," Wright said.

There may also be less focus in the afternoon, as people take on more and more tasks, Lubarsky, who was working at Duke while the study was ongoing, pointed out. "People get distracted trying to relieve colleagues, and the number of cases does indeed go up. Late afternoon meetings occasionally occur and pull you away," he said.

This is not to say that people should forego surgeries later in the day.

"You can''t overgeneralize," Birnbach said. "You can''t say, ''Don''t have surgery in the afternoon.'' "

More information

Visit the National Patient Safety Foundation for resources on anesthesia.

SOURCES: Melanie Wright, Ph.D., assistant professor, anesthesiology, Duke University Medical Center, Durham, N.C.; David Lubarsky, M.D., chairman and professor, department of anesthesiology, University of Miami Miller School of Medicine; David Birnbach, M.D., director, Center for Patient Safety, University of Miami; James S. Hicks, M.D., associate professor, anesthesiology and perioperative medicine, Oregon Health and Science University, Portland, and chairman, American Society of Anesthesiologists Committee on Quality Management and Departmental Administration; August 2006, Quality & Safety in Health Care

Last Updated: Aug. 4, 2006