Effect of chlorhexidine skin disinfection and retrosternal gentamicin sponge on post-sternotomy mediastinitis: results from a prospective controlled registry of 2340 patients.

Background: Reducing post-sternotomy mediastinitis (PSM) requires incorporating multiple methods. However, the independent effects of these measures are not well studied.

Aim: To evaluate the independent effect of preoperative disinfection using isopropyl alcohol (IPA)-chlorhexidine gluconate (CHG) and the topical application of a retrosternal gentamicin collagen sponge at wound closure on reducing PSM.

Methods: From October 2012 to August 2014, 2340 patients were included in this prospective, controlled registry. Patients were divided into four groups. In groups 1 and 2, the skin was disinfected with IPA, and in groups 3 and 4, the skin was disinfected with IPA-CHG. A retrosternal gentamicin collagen sponge was used in groups 2 and 4. Freedom from PSM up to the 30 postoperative day was the primary endpoint. The secondary endpoint was freedom from any surgical site dehiscence. A stepwise regression model was made to reveal the independent factors associated with lower incidence of PSM.

Findings: There were significant differences in outcome among the groups (P < 0.0001). Primary healing was highest in group 4 (91.4%), which showed the lowest rate for mediastinitis (0.9%). Multivariate analysis showed that the use of CHG and a gentamicin sponge was statistically significant (P = 0.026 and 0.013, respectively). The other significant independent factors were valve operation (P = 0.001), body mass index >30 kg/m (P = 0.001), preoperative stroke (P = 0.005), and blood transfusion (P = 0.022).

Conclusion: Preoperative skin disinfection with IPA-CHG is superior to only IPA, and it should be recommended. The addition of a retrosternal gentamicin-releasing sponge further reduces the rate of mediastinitis.