Cefazolin Concentration in the Mediastinal Adipose Tissue of Patients Undergoing Cardiac Surgery

OBJECTIVE: To measure the concentration of cefazolin in the anterior mediastinal adipose tissue of patients undergoing cardiac surgery, determining the variation of cefazolin concentration. METHODS: Two samples of approximately 1g of subcutaneous tissue were collected from 19 patients who underwent surgery in December 2015: the first sample was collected right after sternotomy and the second one, before sternal synthesis with steel wires. Antibiotic dosage was administered through high performance liquid chromatography. RESULTS: We observed a positive and statistically significant correlation between time 1 and cefazolin concentration (r=0.489 and P=0.039). For time 2 and cefazolin concentration, there was a negative and statistically significant correlation between both variables (r=-0.793 and P<0.001). A negative correlation was also observed between body mass index and cefazolin concentration at time 2 (r=-0.510 and P=0.031). The regression model showed that every 1-minute increase in time 1 corresponded to an increase of 0.240 µg/dL in cefazolin concentration, whereas every 1-minute increase in time 2 corresponded to a reduction of 0.046 µg/dL in cefazolin concentration. As for body mass index, every 1 kg/m(2) increase corresponded to a reduction of about 0.510 µg/dL in cefazolin concentration. CONCLUSION: There was a positive and significant correlation between the initial time of surgery and cefazolin level in the first dosage. The evaluation of the second dosage showed a negative and significant correlation between cefazolin level and the second time of dosage. The concentration of cefazolin is under the influence of body mass index.