Antibiotic prophylaxis with cefazolin and gentamicin in cardiac surgery for children less than ten kilograms.

Objective: Antibiotic prophylaxis is recommended in pediatric cardiac surgery, but no data concerning the current antibiotic regimen were available.

Design: Prospective study from April to June 2000.

Setting: University hospital operating room and postoperative intensive care unit.

Participants: Nineteen consecutive infants less than 10 kg with normal renal function undergoing cardiac surgery with cardiopulmonary bypass longer than 30 minutes.

Interventions: Intravenous administration of cefazolin, 40 mg/kg, and gentamicin, 5 mg/kg, at induction of anesthesia; followed by cefazolin, 35 mg/kg every 8 hours, and gentamicin, 2 mg/kg every 12 hours, over 48 hours.

Measurements And Main Results: Levels of serum antibiotics were measured: cefazolin (microbiologic) and gentamicin (fluorescence immunoassay) with 8 intraoperative and 5 postoperative samplings. Intraoperatively, cefazolin levels decreased from 166 +/- 44 (mean +/- standard deviation) down to 54 +/- 16 microg/mL and gentamicin from 20.8 +/- 9.5 down to 5.9 +/- 1.5 microg/mL. The postoperative trough levels were 12 +/- 7, 15 +/- 10, and 19 +/- 22 microg/mL for cefazolin and 1.1 +/- 0.5, 0.8 +/- 0.4, and 0.8 +/- 0.9 microg/mL for gentamicin.

Conclusions: Antibiotic serum levels are consistent with satisfactory efficacy, but intraoperative gentamicin peak levels appeared too high.