Tissue and plasma concentrations of antibiotic during cardiac surgery with cardiopulmonary bypass--microdialysis...

Surgical-site infections are very serious complications of cardiac operations. Use of cardiopulmonary bypass (CPB) is associated with profound physiological changes, which affects the pharmacokinetic behaviour of prophylactic antibiotics. The aim of this study was to monitor tissue concentrations of cefuroxime in peripheral tissue (skeletal muscle) during cardiac surgery using CPB by means of a microdialysis.

Eleven adult patients operated on using CPB were included in the study. Cefuroxime was the prophylactic antibiotic and study drug given. Microdialysis was performed by probe CMA 60 inserted into the patient's left deltoid muscle. Samples of dialysates were collected at intervals: before CPB, each 30 minutes of CPB and at the end of CPB. Samples of blood were collected at intervals: incision, start of CPB, each 30 minutes of CPB, at the end of CPB and at the end of surgery.

The mean (+/- S.D.) concentrations of cefuroxime in peripheral tissue were 105.4+/-41.1, 81.7+/-32.8, 74.6+/-26.0, 70.4+/-34.7, 60.5+/-27.2, 138.0+/-42.6 (mg l(-1)). Total plasma concentrations of cefuroxime were 154.4+/-41.6, 73.3+/-20.7, 67.1+/-20.4, 59.2+/-21.0, 49.0+/-16.4, 110.9+/-33.6 (mg l(-1)) and concentrations of free plasma fraction were 110.7+/-37.1, 62.2+/-18.8, 58.9+/-18.6, 48.4+/-16.6, 41.7+/-15.6, 97.6+/-28.6 (mg l(-1)). The plasma and tissue concentrations exceed throughout the operation time the minimum inhibitory concentration for most common suspected pathogens in cardiac surgery.

Results show that CPB can modify the time course of cefuroxime tissue and plasma concentrations. Microdialysis is suitable for antibiotic tissue measurement in cardiac surgery.