Serum cefazolin levels during cardiopulmonary bypass

This study was done to assess the adequacy of a regimen using cefazolin as a prophylactic antibiotic for patients undergoing open-heart operation. At the time of the preoperative medication, adult patients received 1 gm of cefazolin intramuscularly, and pediatric patients were given a dose of 20 mg per kilogram of body weight. Group I consisted of 10 adults undergoing a variety of cardiac procedures. The mean serum cefazolin level after institution of cardiopulmonary bypass was 27.36 micrograms/ml (range, 13.1 to 40.3 micrograms/ml). This level remained fairly stable throughout cardiopulmonary bypass. Group II consisted of 10 pediatric patients undergoing cardiac procedures for repair of a variety of congenital anomalies. The mean serum cefazolin level after institution of cardiopulmonary bypass was 20.01 micrograms/ml (range, 11.4 to 28.9 micrograms/ml) and remained stable for the duration of the procedure. In both groups perfusion pressure, urinary output, and body temperature did not seem to have any influence on these levels. It is concluded that the administration of one dose of cefazolin intramuscularly before operation results in an adequate and stable serum cefazolin level in patients undergoing cardiopulmonary bypass for up to three hours, possibly longer.