Pharmacokinetics of intravenous vancomycin in pediatric cardiopulmonary bypass surgery.

The purposes of this investigation were to characterize the disposition of vancomycin in children undergoing cardiopulmonary bypass (CPB) surgery and to determine whether a 15-mg/kg intravenous dose provides adequate serum concentrations during and after CPB. Six children (age range, 0.8 to 4.8 years) received intravenous vancomycin 15 mg/kg 1 to 2 hours before CPB surgery. Serial blood samples (mean, 10/patient) were collected before, during and after CPB surgery. The mean (+/- SD) vancomycin concentrations at the end of the infusion and 5 hours after the infusion were 27.3 +/- 5.7 and 5.9 +/- 3.0 mg/liter, respectively. The initiation of CPB resulted in an abrupt decrease (44.5%) in serum vancomycin concentrations; however, concentrations remained constant (range, 6.2 to 14.1 mg/liter) throughout the rest of the CPB procedure. The mean (+/- SD) values for the apparent volume of distribution, total body clearance and elimination half-life were 0.59 +/- 0.15 liter/kg, 2.94 +/- 0.93 ml/min/kg and 2.4 +/- 0.8 hours, respectively. These values were similar to those reported in the literature for children not undergoing CPB surgery. A single vancomycin dose of 15 mg/kg before pediatric CPB surgery provides serum concentrations greater than 5 mg/liter throughout the duration of the CPB procedure. To sustain these concentrations subsequent dosing of vancomycin is necessary within 6 hours after the initial vancomycin dose.