Concentração de cefazolina no tecido adiposo do mediastino de pacientes submetidos à cirurgia cardíaca

Postoperative mediastinitis is a serious infectious complication of cardiovascular surgeries. Antibiotic prophylaxis is one of the main preventive measures that can be taken. However, the use of many, different antibiotics for this purpose clearly indicates that there is no consensus on their efficacy and safety. Our aim was to assess whether the/our cefazolin prophylaxis protocol provides concentration higher than the required/recommended minimum inhibitory concentration in the fatty tissues of the mediastinum [throughout the surgical procedure]. This was done by measuring the variation of the concentration of cefazolin in beginning and at the end of surgery. The analysis of the concentration of the antibiotic in the samples was done by High Performance Liquid Chromatography by reverse phase, in the Keizo Asami immunopathology laboratory, of the Federal University of Pernambuco. Of the 19 patients, evaluated 12(63,15%) were women and 7(36,84%) men with average age of 60.3 ± 8.2 years. Of these patients 16 (84.21%) were hypertensive; 9 (47.36%) were diabetic; 11 (57.8%) had dyslipidemia and 7 (36.8%) were smokers. The performed cardiovascular surgeries were: 14 (73.68%) coronary artery bypass graftings; 4 (21.05%) valve replacements and only 1 (5.26%) of aortic aneurysm correction. As for body mass index, only one patient (5.26%) had a BMI above 40 and 15 (79.84%) had BMI below 30. The average time between the [first] infusion of cefazolin and the first collection was 26m5s (19-35 min) and the average time between the last infusion of the antibiotics and the last collection was 180min (60-210 min). The [average] concentration of cefazolin measured in the first sample was 6.1 μg/ml (4.45-10.86 μg/ml) whilst the average concentration of the antibiotics in the samples taken at the end of surgery was 8,4 μg/ml (4.3-13.02 μg/ml). We conclude that, in this study, the concentration of cefazolin in the mediastinal fatty tissues during cardiovascular surgeries remained within the safety standards set by international organizations.