Continuous Intravenous Insulin Infusion Reduces Incidence of Deep Sternal Wound Infection In Diabetic Cardiac Surgery Patients

Background: Diabetes mellitus (DM) is a risk factor for deep sternal wound infection (DSWI) following open heart surgery. We have previously shown that elevated postoperative blood glucose is a predictor of DSWI in diabetics. Therefore, we hypothesized that aggressive intravenous pharmacologic control of post operative blood glucose would reduce the incidence of deep sternal wound infection. Methods: In a prospective study of 2,467 consecutive diabetic patients who underwent open heart surgery between 1987 and 1997, perioperative blood glucose levels were recorded every 1-2 hours. Patients were divided into two sequential groups: the control group consisted of 968 patients treated with sliding scale guided intermittent subcutaneous insulin injections (SQI); the study group consisted of 1,499 patients treated with a continuous intravenous insulin infusion (CII) in an attempt to maintain blood glucose levels <200 mg/dl. There were no differences between these groups with respect to age, sex, procedure, bypass time, antibiotic prophylaxis, or skin preparation methods. Results: As compared to SQI control, CII induced significant reductions in perioperative blood glucose levels which led to a significant reduction in the incidence of DSWI in the CII group (0.8%) vs. SQI (2.0%) (12/1499 vs. 19/968, chi-square p = 0.01). Multivariable logistic regression revealed that CII induced a significant decrease in the risk of DSWI (p=0.005, relative risk =0.34) while obesity (p<0.03, relative