Vancomycin therapy in critically ill patients on continuous renal replacement therapy; are we doing enough?

BACKGROUND: Recommendations regarding vancomycin dosing and monitoring in critically ill patients on continuous renal replacement therapy (CRRT) are limited. This is a retrospective study to assess the adequacy of current vancomycin dosing and monitoring practice for patients on CRRT in a tertiary hospital in Riyadh, Saudi Arabia. METHODS: A retrospective chart review of adult patients admitted between 1 April 2011 and 30 March 2013 to critical care and received intravenous vancomycin therapy whilst on CRRT was performed. RESULTS: A total of 68 patients received intravenous vancomycin therapy whilst on CRRT, of which 32 met the inclusion criteria. Fifty-one percent were males and median (range) age was 62.5 (19 – 90) years. Median APACHE II score was 33.5 (22–43) and median Charlson Comorbidity Score was 4 (0–8). The mean (± standard deviation) dose of vancomycin was 879.9 mg (± 281.2 mg) for an average duration of 5.9 days (± 3.7 days). All patients received continuous veno-venous haemofiltration (CVVH). A total of 55 vancomycin level readings were available from the study population, ranging from 6.6 to 41.3, with wide variations within the same sampling time frames. Vancomycin levels of > 15 mg/L or were achieved at least once in 24 patients (75.0%), but only 11 patients (34.3%) had 2 or more serum vancomycin level readings of 15 mg/L or more. CONCLUSION: Therapeutic vancomycin levels are difficult to maintain in critically ill patients who are receiving IV vancomycin therapy whilst on CRRT. Aggressive dosing schedules and frequent monitoring are required to ensure adequate vancomycin therapy in this setting.