Weight-Based versus Set Dosing of Vancomycin for Coronary Artery Bypass Grafting or Aortic Valve Surgery

OBJECTIVES:

This study was undertaken to identify a preferred dosing strategy for patients undergoing coronary artery bypass grafting or valve replacement procedures with cardiopulmonary bypass.

METHODS:

Patients undergoing coronary artery bypass grafting, valve replacement surgery, or both were randomly assigned to receive either standard 1-g dosing with vancomycin before and after cardiopulmonary bypass or a single weight-based 20-mg/kg dose before surgery. The primary outcome was the percentage of time plasma concentrations were greater than 15 μg/mL during cardiopulmonary bypass and at surgical closure. Secondary outcomes included concentration of vancomycin in endothoracic tissue after vancomycin infusion, average time patients had vancomycin concentrations greater than 15 μg/mL, and vancomycin plasma and tissue pharmacokinetic parameters.

RESULTS:

Baseline characteristics were similar between the study dosing group (n = 10) and the standard dosing group (n = 10). From postinfusion to end of bypass, the median percentage of time vancomycin concentrations remained greater than 15 μg/mL was 100% (interquartile range [IQR], 72.6%-100%) for weight-based dosing versus 43.7% (IQR, 28.7%-53.4%) for standard dosing (P = .0005). From postinfusion to surgical closure, the percentage of time vancomycin concentrations remained greater than 15 μg/mL was significantly higher in the weight-based group (100% [IQR, 58.3%-100%] vs 34.6% [IQR, 25.3%-41.6%]; P = .0005). Weight-based dosing increased calculated time with vancomycin concentrations greater than 15 μg/mL and resulted in higher endothoracic tissue vancomycin concentrations.

CONCLUSIONS:

Weight-based vancomycin dosing before coronary artery bypass grafting or valve replacement results in vancomycin concentrations greater than 15 μg/mL consistently more than does standard 1-g dosing.