Changes of the serum antibiotic levels during open heart surgery (ceftazidim, ciprofloxacin, clindamycin)
V. Lonský, J. Dominik, J. Mand’ák., E. Pozlerová, M. Hejzlar, V. Lonská, M. Maršíková, J. Kubíæek, M. Snítilová

Background: Wound, mediastinal and intra-cardiac infections are still very serious complications of open heart surgery. The incidence of it is still in the range of 0,4%-5%. The aims of our study were to assess the adequacy of regimen using ceftazidim (CTZ), ciprofloxacin (CPF) and clindamycin (CLIN) as prophylactic antibiotics and to verify whether cardiopulmonary bypass (CPB) can modify the time of antibiotic serum concentrations. That is why their serum levels were measured during open heart procedures.

Methods: The prospective study comprised 75 consequent coronary patients randomized into three groups receiving 1 g of CTZ or 400 mg of CPF  or 900 mg of CLIN i.v. with anaesthesia induction. Routine coronary surgery with left internal mammary artery harvesting, moderate body hypothermic (30º C) CPB with  crystaloid cardioplegia was performed. Serum antibiotic levels  were determined before application with skin incision, prior to CPB induction, after cardioplegia infusion, every 20 minutes of CPB, prior to end of CPB, at time of chest closure. Conventional cylinder – plate microbiological assay was used for antibiotic level measurement.

Results:  All serum antibiotic concentrations showed a sharp decrease immediately after starting CPB and lasted until CPB ended. After initiating CPB after cardioplegia administration serum concentrations of CTZ (105 min after initial dose) decreased by, on average 55%,  CPF ( 97 min) by 42% and CLIN (116 min) by 78%.

Conclusion:  CPB can modify the time course of antibiotic serum concentrations. The serum levels of CTZ  at the end of the longest procedures were found to be below the MICs for some of the suspected pathogens. We recommend using higher antibiotic doses for prophylaxis and administering the second dose with protamin sulphate to obtain maximum concentration in newly formed blood clots.

Keywords: cardiac surgery, cardiopulmonary bypass, antibiotic prophylaxis, serum antibiotic concentrations

Applied Cardiopulmonary Pathophysiology 9: 326-332, 2000

Vladimír Lonský, M.D., Ph.D.
University Department of Cardiac Surgery
University Hospital
Hradec Králové 500 05
Czech Republic
E-mail: vlonsky@usa.net