Monitoring vancomycin in an intensive care unit: A retrospective survey on 66 patients

Objectives

The study objectives were to check whether recommended vancomycin doses were related to pharmacological objectives for intensive care patients: steady-state plasma concentration (SSc) and ratio SSc/MIC (Minimal Inhibiting Concentration). The authors tried to identify variability factors for vancomycin plasmatic concentrations at peak.

Patients and methods

This monocentric, observational, and retrospective survey was performed on 66 intensive care patients treated by antibiotics including vancomycin, alone or in combination, as a curative treatment for a severe infection with Gram-positive bacteria. Vancomycin was dosed at 15 mg/kg during the first hour, then 40 to 60 mg/kg per 24 hour. Vancomycin SSc and bacteria MIC were recorded. The SSc/MIC ratio was determined and was considered efficient when superior to 8.

Results

Forty-two percent of vancomycin SSc were within the effectiveness rate. Twenty-three percent of SSc/MIC ratios were superior to 8. The rate of clinical recovery was 71 %. The length of antibiotherapy was identified as positively interacting with biological effectiveness, unlike severe sepsis, a factor of negative interaction on vancomycin SSc in this study.

Conclusion

Less than half of the SSc and less than a quarter of the SSc/MIC ratios were at effective rates in our study. Therefore, adequacy between dosage, administration, and monitoring should be reviewed.