MEDIASTINITIS IN PATIENTS UNDERGOING CARDIOPULMONARY BYPASS - RISK ANALYSIS AND MIDTERM RESULTS

Background Deep sternal wound infection (mediastinitis) occurred in. 2 1 out of 4043 consecutive patients who underwent a cardiopulmonary byp ass procedure (incidence of 0.4%). Methods. Clinical characteristics o f patients who developed mediastinitis (group I) were compared to thos e of patients who had no mediastinal infection (group II). Results. Ho spital mortality was significantly higher in group I (14% us 3.8%) (p< 0.001). Mean hospital stay Tvas longer in group I(36 days us 7 days) ( p<0.001). Multivariate analysis identified the following variables as significant risk factors for developing postoperative mediastinitis: d iabetes; relative risk (RR)=3.02, 95% confidence limits (CL)=1.68-5.45 , resternotomy for bleeding: RR=5.43, CL=1.85-15.92, associated leg wo und infections; RR=16.55, CL=5.32-51.49, the need for 3 or more units of blood transfusion; RR=2.48, CL=1.82-3.39, obesity; RR 4.96, CL 2-12 .25. Group I patients were categorised according to a recently propose d classification for mediastinitis (reference 1). Type I(n=17), medias tinitis presenting within 2 weeks following surgery in the absence of risk factors. Type II (n=2), mediastinitis presenting at 2-6 weeks fol lowing surgery in the absence of risk factors. Type IIIA. (n=2), media stinitis type I in the presence of one or more risk factor(s). Wound d ebridement and closed mediastinal irrigation was performed in 19 patie nts; 15 cases with type I, 2 with type TI, and 2 with type IIIA. Prima ry closure without irrigation was performed in 2 type I patients. The primary intervention failed in 3 patients, two of whom died. A third p atient died 4 weeks after an apparently successful treatment of type I mediastinitis. Midterm follow-up (mean of 18 months) of 18 patients s howed that 16 patients were alive and well, there was one late death, and one patient had chronic wound pain. Conclusion. Diabetes, obesity, associated leg-wound infection, and the need for repeated blood trans fusions are associated with high risk of mediastinitis. Closed mediast inal irrigation for mediastinitis type I can yield satisfactory functi onal and cosmetic midterm results.