Cefazolin concentrations in serum during cardiopulmonary bypass surgery.

The objective of the study was to investigate possible changes in cefazolin serum levels induced by cardiopulmonary bypass (CPB). Six cardiac male patients who underwent cardiac surgery requiring CPB took part in the study. Cefazolin 2 g was intravenously infused over 60 min before anesthesia and blood samples were taken at appropriate times after drug administration (0, 0.25, 0.5, 1, 4, 6, 8 h), 2 min before and 5 min after the beginning and 2 min before and 5 min after the end of CPB. Drug serum concentrations were determined by means of a microbiological method. Five minutes after the start of CPB, cefazolin serum levels decreased on average by 46.6% and remained steadily low until 5 min after the end of CPB. Then, they rose on average by 37.3% at 4 h and then declined slowly until the last sampling at 8 h. Cefazolin serum concentrations were low during CPB but remained in a potentially effective range for antimicrobial prophylaxis for this surgery.