MEDIASTINITIS AFTER CARDIOVASCULAR OPERATIONS - A CASE-CONTROL STUDY OF RISK-FACTORS

Background. An analysis of risk factors for postoperative mediastiniti s can lead to a better understanding of the pathogenesis of this compl ication and to more effective preventive measures. Methods. This case- control study of 37 patients and 74 matched controls evaluated 54 pote ntial risk factors. Results. Nine variables were significantly associa ted with increased risk of postoperative mediastinitis: total operatio n time (p = 0.0013), high body-mass index (p = 0.0033), use of beta-ad renergic drugs before the onset of infection (p = 0.0037), long cardio pulmonary bypass time (p = 0.0072), long aortic cross-clamp time (p = 0.0075), presence of diabetes (p = 0.0122), high body weight (p = 0.01 30), and use and duration of temporary pacing wires (p = 0.0293 and p = 0.0241 respectively). In a conditional logistic regression analysis, use of beta-adrenergic drugs before the onset of infection (p = 0.005 8; odds ratio 19.7; 95% confidence limits, 2.37 and 163.7) and body ma ss index (p = 0.0082; odds ratio 1.27; 95% confidence limits, 1.06 and 1.52) were independently associated with a significantly increased ri sk of postoperative mediastinitis. Conclusions. Obesity and use of bet a-adrenergic drugs, which is indicative of obstructive respiratory pro blems, were the most important risk factors suggesting that mechanical strain on the sternotomy and sternal instability may precede infectio n. Targeted preventive measures for these groups could be justified. ( C) 1998 by The Society of Thoracic Surgeons.