ABC | Volume 112, Nº6, June 2019

Original Article Andrade et al. Surgical site infection prevention bundle in cardiac surgery Arq Bras Cardiol. 2019; 112(6):769-774 reduce SSI rates in patients who undergo surgical procedures. 3 Furthermore, confirming the findings of our study, diagnosis of diabetes mellitus, regardless of blood glucose level, increases the risk of SSI in cardiac surgery. The SCIP, which was founded in 2003 as a national-level partnership of organizations committed to improving surgical care safety by reducing postoperative complications, developed a core measure to maintain blood glucose level at ≤ 180mg/dL during the perioperative and postoperative periods, based on evidence that this reduces SSI in cardiac surgery. 10,13,14 The Society for Healthcare Epidemiology of America (SHEA) and the Infectious Diseases Society of America (IDSA) also recommend blood glucose level goal of ≤ 180 mg/dL during the immediate postoperative period. According to a study conducted by the Society of Thoracic Surgeons, it has been demonstrated that maintaining blood glucose levels between 150 mg/dL and 180 mg/dL reduces the risk of SSI in cardiac surgery. 7,15 A randomized controlled study of 5,510 diabetic cardiac surgery patients, with an intravenous insulin protocol used tomaintain blood glucose at ≤150mg/dL, demonstrated that the use of this protocol is safe and that it led to a 77% reduction in SSI. 16 Obesity is a risk factor for SSI in cardiac, colorectal, orthopedic, caesarean section, and general surgery, as the procedure becomes more complex and increases the duration of surgical stay, causing tissue hypoxia and hyperglycemia related to the obese patients’ insulin resistance, thus, contributing to the risk of SSI. Obese patients have a higher risk of acquiring infections, especially when they are exposed to surgical procedures and hospitalization in intensive care units. 17-19 A study conducted in the USA demonstrated that risk of infection was 4.7 times higher in obese surgery patients and 6 times higher in surgery patients with morbid obesity, in comparison with normal-weight surgery patients. 19 Furthermore, a recent study followed up 33,936 patients after myocardial revascularization surgery, showing that the factors that determined high risk of surgical infection included female sex, obesity, unplanned reoperations, and longer hospital stays. 20 In our study, the risk of infection related to obesity was 1.8 times higher. The surgical risk index is a good predictor of risk in surgeries. In one study, the use of NNIS risk index contributed to the stratification of SSI incidence rates in cardiac surgery. In this study, the incidence of mediastinitis was 0% when the patient’s score was 0, 1.2% when it was 1, and 2.3% when it was 2. 21,22 Our study demonstrated that in clean surgeries, the component related to base pathologies, patient’s physical state (ASA class), and procedure duration, as measured by NNIS risk index, was associated with a higher risk of infection. Although obesity and diabetes mellitus are modifiable factors in most cases, these pathologies may signal greater risks. Healthcare professionals may then take greater care with the patient, for example, with strict attention to the surgical technique, dead space reduction, tissue circulation, and postoperative care. There are some limitations to our study. It is a retrospective study of only one cardiology center. Although we assessed the patients’ physical state and risk factors (ASA class) and procedural risks (length of surgical stay), the final analysis did not include some risk factors, such as patient skin antisepsis (preoperative); the surgical team’s abilities and operating room assistants’ behavior (intraoperative); surgical sterilization practices; the use of invasive procedures during the postoperative period, such as catheters, probes, or mechanical ventilation; and other risk factors related to infection. Conclusion Obesity, diabetes, and blood glucose level were independent factors associated with SSI in patients who underwent major cardiac surgery procedures. Surgical risk index was a good predictor score for SSI in cardiac surgery. Surgical antibiotic prophylaxis and adherence to the SSI prevention bundle for cardiac surgery were not associated with a decrease in SSI risk. Author contributions Conception and design of the research and Critical revision of the manuscript for intellectual content: Andrade L, Siliprandi EMO, Pires R; Acquisition of data: Andrade L, Siliprandi EMO, Karsburg LL, Berlesi FP, Carvalho OLF, Rosa DS, Pires R; nalysis and interpretation of the data and Obtaining financing: Andrade L, Pires R; Statistical analysis: Andrade L, Karsburg LL, Berlesi FP, Pires R; Writing of the manuscript: Andrade L, Siliprandi EMO, Carvalho OLF, Rosa DS, Pires R. Potential Conflict of Interest No potential conflict of interest relevant to this article was reported. Sources of Funding There were no external funding sources for this study. Study Association This article is part of the thesis of master submitted by Lilian Silva de Andrade, from Instituto de Cardiologia do Rio Grande do Sul. Ethics approval and consent to participate This study was approved by the Ethics Committee of the Instituto de Cardiologia - Fundação Universitária de Cardiologia - Unidade de Pesquisa under the protocol number 4997/14. All the procedures in this study were in accordance with the 1975 Helsinki Declaration, updated in 2013. Informed consent was obtained from all participants included in the study. 772