Increased Total Anesthetic Time Leads to Higher Rates of Surgical Site Infections in Spinal Fusions

Study Design. A retrospective review of a consecutive series of spinal fusions comparing patient and procedural characteristics of patients who developed surgical site infections (SSIs) after spinal fusion. Objective. It is known that increased surgical time (incision to closure) is associated with a higher rate of postoperative SSIs. We sought to determine whether increased total anesthetic time (intubation to extubation) is a factor in the development of SSIs as well. Summary and Background Data. In spine surgery for deformity and degenerative disease, SSI has been associated with operative time, revealing a nearly 10-fold increase in SSI rates in prolonged surgery. Surgical time is associated with infections in other surgical disciplines as well. No studies have reported whether total anesthetic time (intubation to extubation) has an association with SSIs. Methods. Surgical records were searched in a retrospective fashion to identify all spine fusion procedures performed between January 2010 and July 2012. All SSIs during that timeframe were recorded and compared with the list of cases performed between 2010 and 2012 in a case-control design. Results. There were 20 (1.7%) SSIs in this fusion cohort. On univariate analyses of operative factors, there was a significant association between total anesthetic time (Infection 7.6 +/- 0.5 hrs vs. no infection -6.0 +/- 0.1 hrs, P< 0.001) and increasing operative time (infection 5.5 +/- 0.4 hrs vs. no infection - 4.4 +/- 0.06 hrs, P< 0.01) with infections, whereas level of pathology and emergent surgery were not significant. On multivariate logistic analysis, BMI and total anesthetic time remained independent predictors of SSI whereas ASA status and operative time did not. Conclusion. Increasing BMI and total anesthetic time were independent predictors of SSIs in this cohort of over 1000 consecutive spinal fusions. Key words: anesthetic, body mass index, fusion, infections, site, spine, surgery, surgical, time, total.