Cardiac and respiratory complications, along with other problems not directly related to surgery, were the most common causes of unplanned hospital admissions after ambulatory surgery, according to a retrospective study at Duke University Medical Center, in Durham, N.C. Surgical-related reasons, including complications or necessary additional procedures, were the next most common. The study was presented at the 2011 annual meeting of the American Society of Anesthesiologists (ASA; abstract 849).

The investigators reviewed the charts of 28,456 patients who underwent ambulatory surgery between May 2006 and May 2010 at a freestanding surgical center adjacent to Duke University. They included all cases admitted directly after the procedure and cases from the ambulatory center’s 23-hour observation unit. Demographic variables were obtained from the medical center’s electronic records; hospital charges attributed to inpatient admissions were pulled from an internal financial database.

During the study period, unplanned hospital admissions accounted for 127 patients, a rate of 0.45%, which is comparable to previously published findings. The average age of the patients was 48 years; average body mass index was 30 kg/m2. Fifty-one percent were classified as ASA physical status I/II; the remainder of the patients were classified as ASA III/IV and were obese.

Medical-related issues accounted for 32% of admissions (41 cases) and were associated with the highest total charges ($356,392); treating cardiac complications was the most expensive ($177,283). Surgical-related reasons accounted for 22% of admissions (28 cases) and were associated with the next highest charges ($311,311); treating surgical complications was the most expensive ($137,367).

Other reasons for admission included need for additional pain control (27 cases), postoperative antibiotics (13 cases), postoperative bleeding (11 cases), anesthesia-related complications (four cases) and adverse drug reactions (three cases).

Steve Melton, MD, assistant professor of anesthesiology at Duke and a co-author of the study, said the results were more confirmatory than surprising. “It shows we’re doing a better job of identifying appropriate patients for ambulatory surgery, and identifying and managing risk factors beforehand,” Dr. Melton said. Risk identification should be a team approach from surgeons and anesthesiologists, although “some of this stuff you can’t always prepare for,” he added.