Surgical site infection (SSI) is a serious operative complication that may be associated with any surgical procedures. It increases morbidity and mortality after cardiac surgery. Plasma concentration of prophylactic antibiotic, routinely cefazolin, is altered by effects of cardiopulmonary bypass. This study is conducted to measure the plasma concentrations of cefazolin to determine its adequacy in pediatric patients undergoing elective cardiac surgery with cardiopulmonary bypass including its correlation with the incidence of postoperative SSI.

Inclusion Criteria:

1. age < 7 years old
2. undergoing elective cardiac surgery with cardiopulmonary bypass
3. receive cefazolin as prophylactic antibiotic

Exclusion Criteria:

1. Known or family history of penicillin or cephalosporins allergy
2. Coexisting liver or renal disease
3. Previous infection or received any antibiotics within 4 weeks
4. Previous surgery with median sternotomy
5. Predicted cardiopulmonary bypass time of less than 30 minutes or more than 150 minutes
6. Severe hemodynamic instability during the operation, requiring mechanical circulatory support

Pediatric patients whose age less than 7 years old, undergo elective cardiac surgery with cardiopulmonary bypass.