[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 15mg/kg during the first hour, then 40 to 60mg/kg per 24hour. 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.