Factores asociados al riesgo de mediastinitis postoperatoria en cirugía cardiovascular en el Instituto Nacional del Corazón (INCOR) Translated title: Associated risk factors for mediastinitis post cardiovascular surgery in the Instituto Nacional del Corazón (INCOR)

Background Mediastinitis is a rare, but serious complication of cardiac surgery. It has a significant socioeconomic impact and high morbidity. The purpose of this study was to determine pre-, intra-, and postoperative predictors of mediastinitis. Methods and results In 1700 consecutive patients, who underwent cardiac surgery in 2001, 49 variables were retrospectively assessed. Forty-five patients (2.65%, 95% CI [1.88; 3.41]) developed postoperative mediastinitis. None of these patients died during their hospitalization. Multivariate analysis identified three of the 49 variables as highly significant independent predictors for the development of mediastinitis: obesity (OR 1.03, 95% CI [1.01; 1.04] p = 0.001), chronic obstructive pulmonary disease (OR 3.30, 95% CI [1.58; 6.88], p = 0.001), and bilateral grafting of the internal mammary artery (OR 3.18, 95% CI [1.20; 8.43] p = 0.02). The model is reliable in terms of its goodness of fit, it also discriminates well. Additionally, univariate analysis identified diabetes mellitus, CCS class and the number of intraoperatively transfused units of fresh frozen plasma as variables with a significant impact. Conclusion The present study suggests that bilateral IMA grafting, chronic obstructive pulmonary disease and obesity are important predictors of mediastinitis.

Poststernotomy mediastinitis as a complication is rare but disastrous. We assessed incidence, predisposing factors for, and outcome from, mediastinitis after cardiac surgery. We studied 10,713 consecutive patients who underwent open-heart surgery from 1990 to 1999 in a tertiary care university hospital using data prospectively recorded in the hospital discharge register, operating room log, and the hospital's cardiothoracic surgery unit register. Those cases with possible mediastinitis were identified from the hospital infection register and discharge register. Patients' charts were reviewed and cases of mediastinitis confirmed based on criteria of the Centers for Disease Control and Prevention. The overall rate of mediastinitis was 1.1% (120 cases), and higher in coronary artery bypass surgery than in valvular surgery (1.2 vs 0.8%). No trend in incidence was detectable, although surgical patients became progressively older (mean age, 59 to 65 years, p 30 kg/m2), rates of mediastinitis were 0.5%, 1.0%, and 1.8%. In multivariate analysis adjusted for age, sex, year, operation type, and perfusion time, the only predictor for mediastinitis was BMI. Mediastinitis is not diminishing. Larger populations at risk, for example proportions of overweight patients, reinforce the importance of surveillance and pose a challenge in focusing preventive measures.

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether bilateral internal thoracic artery (BITA) coronary bypass increases the risk for mediastinitis. Using the reported search 140 papers were identified. Twenty-four papers represented the best evidence on the subject and the author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and study comments and weaknesses were tabulated. In general, BITA grafting carries a 2.5- to 5-fold higher risk for mediastinitis after CABG. This risk is about 1.3-4.7% in non-diabetic patients compared to 0.2-1.2% for single internal thoracic artery (SITA) grafting. For diabetic patients with BITA grafting the risk of mediastinitis is significantly increased and can be as high as >10% in some series. However, for patients who undergo BITA harvest using skeletonization the risk is significantly lower and may be similar to patients receiving SITA graft only at around 0.4-2.6%. BITA grafting can be performed with acceptable risk in all patients including higher risk patients such as diabetics, in whom skeletonization of the internal thoracic arteries should be strongly considered rather than pedicled harvest.