The incidence of postoperative wound infection following bowel surgery ranges from 5 to 13%. Factors associated with a decreased risk of infection include use of prophylactic antibiotics, avoidance of intraoperative hypothermia and use of a preoperative mechanical bowel prep. However, few studies have investigated the relative contribution of these variables in combination to wound infection. Our study examines the relationship of a number of variables to perioperative wound infection.
From August to October, 2002, data on patients (n=50/site) undergoing bowel surgery from 30 medical centers were collected. Variables that were considered important with regard to the risk of developing perioperative wound infection were analyzed using logistic regression analysis. Variables with a p value <0.25 in the univariate model were included in the multivariate model: wound class, preoperative administration of prophylactic antibiotics within 120 minutes of incision, lowest intraoperative temperature, duration of surgery (hourly intervals) and supplemental oxygen administration in the post anesthetic care unit (PACU).
The overall infection rate was 9.5% in 1447 patients. Preoperative administration of antibiotics within 120 minutes of incision was associated with a lower risk of wound infection (7.6% vs 13.4%, p<0.05). Surprisingly, patients with a wound infection had a higher mean intraoperative temperature nadir than those without an infection (36.0+0.9 vs 35.8+0.8°C, p<0.05). Variables (with odds ratios and p values) in the multivariate analysis are presented in the tableVariableWound ClassAntibioticLow TempTransfusionSupplemental O2Surgical Timep value0.220.04*0.01*0.710.190.04*Odds ratio1.190.590.700.0.930.731.13+/− 95% confidence interval0.90, 1.590.36, 0.970.53, 0.930.62, 1.380.45, 1.171.01, 1.27.
Like previous studies, we show that preoperative administration of prophylactic antibiotics was associated with a lower risk of surgical wound infection following bowel surgery. Although blood transfusions have been implicated in perioperative nosocomial infections, no such association was seen in this study. Contrary to previous investigations, hypothermia was associated with a lower risk of infection. This consequence could be a result of the use of convective warm air blankets to prevent hypothermia.
This study affirms the importance of the timely preoperative administration of prophylactic antibiotics to reduce the incidence of wound infection following bowel surgery.
J.M. Walz, None.