Duration of antibiotic prophylaxis for cardiac surgery: prospective observational study

To assess the effect of prolonging antibiotic prophylaxis in cardiac surgery.

Prospective before-after cohort study. In 2004, cefazolin was given pre- and intraoperatively at 1g doses while in 2007 it was continued after surgery for 24h. All consecutive adult patients undergoing coronary artery bypass graft, valve, and/or aortic operations during the study periods were included. The primary outcomes were deep sternal wound infection (DSWI) and mortality. Univariate and multivariate analyses were conducted to assess risk factors for DSWI.

954 patients between 1/2004 and 12/2004 were compared to 424 patients between 1/2007 and 6/2007. In 2007, there were significantly more patients >60yrs., emergency and combined operations and the mean logistic EuroSCORE was higher compared to 2004 (8.53% vs. 6.92%, p=0.006). The rate of DSWI decreased non-significantly from 3.8% (36/954) in 2004 to 2.6% (11/424) in 2007, p=0.27. The adjusted odds ratio of the study period for DSWI was 0.89 (95% confidence interval 0.70-1.13). There was no difference in 30-day (5.2% vs. 5.4%) or 6-month mortality (9.2% in both periods), despite increasing patients' risk.

Increasing the duration of antibiotic prophylaxis did not result in a significant decrease in DSWI. The value of prolonging antibiotic prophylaxis after cardiac operations should be further evaluated.