Hyperglycemia Increases Postop Infection Rate
NEW YORK — Postoperative hyperglycemia boosts the 30-day risk of infectious complications—regardless of preoperative glucose level or whether a patient has diabetes—according to a study of 995 patients undergoing general or vascular surgery in non-ICU settings.
The clinical implications of this finding are that postoperative blood glucose monitoring should be a routine part of patient management, and that maintaining euglycemia postoperatively is a simple intervention that could significantly reduce postoperative infection rates, Dr. Selwyn O. Rogers Jr. said at the annual meeting of the American Surgical Association.
More than 2 million postoperative infections occur annually in U.S. patients. Tight postoperative glucose control has previously been shown to reduce the risk of wound infection in diabetic patients and to lower morbidity and mortality in cardiac surgery patients, as well as in critically ill patients in surgical ICUs. But the impact of perioperative hyperglycemia on postoperative infection risk hadn't previously been studied in noncardiac surgery patients in non-ICU settings—the sort of patients general surgeons see every day, said Dr. Rogers of Brigham and Women's Hospital, Boston.
Dr. Rogers reported on 995 consecutive patients who underwent major general or vascular surgery at Brigham and were enrolled in the observational American College of Surgeons National Surgical Quality Improvement Program. The program's goal is to reduce preventable surgical morbidity and mortality by 25% by 2010.
Postoperative infections—including wound infections, pneumonia, sepsis, urinary tract infections, and septic shock—occurred within 30 days in 117 of the 995 study participants, or 11.7%. The incidence was 15.3% among the 13% of subjects who had diabetes and 8.8% in nondiabetic patients. Patients who developed postoperative infections had a mean postoperative blood glucose level of 142 mg/dL and were significantly older as well as more likely to have received more than two units of RBCs intraoperatively.
A multivariate regression analysis showed only three significant predictors of postoperative infections: emergent surgery and a higher American Society of Anesthesiologists classification—which are factors beyond control—and postoperative hyperglycemia, which is readily manageable. A postoperative blood glucose level 40 mg/dL higher than normal was independently associated with a 30% increased risk of postop infection. And a postop blood glucose greater than 180 mg/dL was associated with an adjusted twofold increase in infection risk.
Preoperative blood glucose level, race, age, and diabetes status, however, were not related to the risk of postoperative infection, Dr. Rogers said.
There was a particularly strong relationship between postoperative hyperglycemia and the risk of surgical site infections, which account for roughly one-quarter of all postoperative infections occurring annually in U.S. patients. Prevention and prompt treatment of postop hyperglycemia, therefore, could potentially have a major favorable impact on the quality of surgical services, he noted.
Dr. Hiram C. Polk Jr. observed that the fascination with tight blood glucose control in surgical patients is only 7 or 8 years old. The pendulum has recently begun to swing away from tight control, but this careful study will push it back, he predicted.
Dr. Polk added that in his own ongoing prospective study of surgical practices at small community hospitals, he has been struck by the uniformly careful attention given to avoiding hypothermia, in contrast to the spotty performance regarding perioperative blood glucose monitoring.
“Hypothermia is being avoided in 98% of cases. On the other hand, nearly one-third of all diabetics are not monitored for intraoperative glucose during long surgical procedures. And 29% of people with very high glucose in the holding area don't get their blood glucose monitored at all,” said Dr. Polk, senior professor of surgery at the University of Louisville (Ky.).
Strict perioperative blood glucose control is routine only in cardiac surgery, because of the abundant evidence that it influences outcomes, Dr. E. Patchen Dellinger pointed out, adding that it's irrational not to apply the same practice in other fields of surgery.
“Clearly the biology is the same,” argued Dr. Dellinger, professor and vice chairman of surgery and chief of the general surgery division at University of Washington Medical Center, Seattle.
“There are still nonbelievers who are unconvinced of this important relationship,” commented Dr. Dana K. Andersen, professor and vice chair of surgery at Johns Hopkins University, Baltimore.
Maintaining euglycemia postoperatively is a simple intervention that could reduce infection rates. DR. ROGERS
