Vancomycin clearance during continuous venovenous haemofiltration in critically ill patients

The objective of this study was to determine the pharmacokinetics and dosing recommendations of vancomycin in critically ill patients receiving continuous venovenous haemofiltration (CVVH). A prospective study was conducted in the Intensive Care Unit of a university hospital. Seven patients receiving CVVH with a triacetate hollow-fibre dialyser were enrolled. CVVH was performed in pre-dilution mode with a blood flow rate of 200–250 mL/min and an ultrafiltrate flow rate of 800–1200 mL/h. To determine vancomycin pharmacokinetics, serum and ultrafiltrate were collected over 12 h after a 2-h infusion of 1000 mg vancomycin. The mean (± standard deviation) sieving coefficient of vancomycin was 0.71 ± 0.13, which is consistent with previously reported values. Clearance of vancomycin by CVVH (0.73 ± 0.21 L/h or 12.11 ± 3.50 mL/min) constituted 49.4 ± 20.8% of total vancomycin clearance (1.59 ± 0.47 L/h) and was consistent with previously reported clearances. Approximately one-fifth of the vancomycin dose was removed during the 12-h CVVH (213.9 ± 104.0 mg). The volume of distribution was 24.69 ± 11.00 L, which is smaller than previously reported. The elimination rate constant and terminal half-life were 0.08 ± 0.05 h−1 and 12.02 ± 7.00 h, respectively. In conclusion, elimination of vancomycin by CVVH contributed to ca. 50% of the total elimination in critically ill patients. The maintenance dose of vancomycin, calculated from parameters from patients in this study, would be 500–750 mg every 12 h to provide a steady-state trough concentration of 15–20 mg/L. Owing to alterations in clinical conditions, serum vancomycin concentrations must be closely monitored in critically ill patients.