IJCS | Volume 31, Nº2, March / April 2018

164 rooms, are also mentioned. 10,11 Other mentioned conditions are antibiotic prophylaxis, intraoperative complications, 5 excessive electrocautery use and previous corticosteroid therapy. 12,13 Postoperative risk factors include prolonged hospital stay and length of stay in Intensive Care Units (ICU), bleeding, respiratory, nephrological and gastrointestinal complications, and the need for surgical reintervention, as well as tracheostomy and sternal instability. 5,9,12,13 Many risk factors have been associated with the development of mediastinitis; however, they vary among institutions, disclosing the need for studies in different hospitals. It is also necessary to verify the bacteriological diagnosis, generally with presence of Staphylococcus aureus or Staphylococcus epidermidis , responsible for 70% to 80% of cases. 14 The aim of this study was to evaluate the profile of patients submitted to sternotomy for the treatment of heart diseases and identify the risk factors for the development of mediastinitis, as well as to evaluate the bacteriological diagnosis of these cases, in a large hospital in Belo Horizonte, state of Minas Gerais (MG), Brazil. Methods This is a case-control study, carriedout in a large hospital in the city of BeloHorizonte (MG), withdata obtained from medical records of patients older than 18 years submitted to cardiac surgery from January 2015 to January 2016. The sample consisted of 65 patients, with and 52 controls paired by gender and age at a ratio of 1:4. The case group consisted of patients diagnosed with post-sternotomymediastinitis confirmed by the Hospital Infection Control Service and by the attending surgeon. The control group consisted of patients submitted to sternotomy during the same period, who did not develop mediastinitis. A data collection form was created, which contained information on the patient’s characteristics (gender and age), pre-surgical conditions (date of hospital admission and surgery), and pre-surgical risk factors (alcohol consumption, smoking, sedentary lifestyle, obesity, DM, dyslipidemia, hypertension, chronic obstructive pulmonary disease (COPD), CRF, class III congestive heart failure, cerebrovascular accident, coronary artery disease and previous cardiac surgery), in addition to the LVEF value. The assesses trans-surgical condition was time of Extracorporeal Circulation (ECC). In relation to the postoperative period, the following were assessed: date of hospital admission and hospital and ICU discharges; fever (> 38.3°C); post-surgical creatinine and death. Prophylactic drugs and bacteriological diagnosis were also evaluated in the cases. Statistical analysis Qualitative variables were described as counts and percentages, and the quantitative variableswere described as mean ± standard deviation or median ± interquartile range, according to data normality, tested by the Shapiro‑Wilks test. For the comparison ofmeans, Student's t -tests and Wilcoxon Mann-Whitney tests were used for independent samples, when appropriate. The association between categorical variables was assessed using Fisher's exact test. The level of significance was established at 5%. The combined effect of the variables on the groups was assessed using the logistic regressionmodel. The variables with p < 0.20 in the bivariate analysis were included in the multiple model, and the backward strategy was used for variable selection. The final model included the variables with p < 0.05 and the variable age, maintained at the researchers’ discretion. The results are shown as Odds Ratio (OR) and their respective 95% confidence intervals. (95%CI). The quality of the adjustment was assessed by theHosmer-Lemeshow test. The analyseswere performed using the free software R, version 3.1.3. Results The sample consisted of 65 patients. There was a predominance of themale gender (63.1%) with amean age of 58.8years (±10.3). Themost common typeof surgerywas coronary artery bypass grafting (CABG) (78.5%), followed by valve replacement (27.4%). The median number of preoperative risk factors was 4 (± 2). The most commonly usedprophylactic antibioticswere cefuroxime (67.7%) and vancomycin (67.7%). Regarding cefuroxime, its use was lower in patients who had a diagnosis of mediastinitis (Table 1). Regarding diabetes mellitus, 45.2% of the cases were diabetic and 33.3%were insulin‑dependent, although no statistically significant differences were observed between the groups. Previous cardiac catheterization was performed in 93.8% of the patients. A median LVEF of 60 (± 19.3%) and mean ECC time of 80 ± 40.3 minutes were observed. The median time of post-surgical hospitalization was 13 days (± 15), and this time was longer in patients Pinto et al. Factors Associated with Post-Sternotomy Mediastinitis Int J Cardiovasc Sci. 2018;31(2)163-172 Original Article