Serum oxacillin and cephazolin levels during cardiopulmonary bypass

Abstract

This study was carried out to assess the adequacy of the dosing regimen for the oxacillin and cephazolin, employed as prophylactic antibiotics for patients undergoing open-heart surgery. The serum levels of both antibiotics were measured during cardiopulmonary bypass. The highest serum levels of both antibiotics were found 30 minutes after their administration (> 24mg/l). During perfusion the serum levels were not stable and decreased to < 2mg/l after 180 minutes in the oxacillin group and after 150 minutes in the cephazolin group. These levels are below the minimum inhibitory concentrations for anti-staphylococcal activity. A second dose of antibiotic at the end of cardiopulmonary bypass should be administered in order to maintain an anti-staphylococcal concentration of antibiotics in the newly formed blood clots. Earlier administration of both antibiotics is recommended in cases where perfusion time exceeds the above mentioned intervals.