Levels of vancomycin in the cerebral interstitial fluid after severe head injury

Abstract

Objective: To evaluate the concentrations of vancomycin in the cerebral interstitial fluid after intravenous administration by multiple boli.

Design: Prospective non randomized study

Setting: University hospital general ICU.

Patients: Four patients undergone to craniotomy for evacuation of cerebral posttraumatic hemorrhage, who developed pneumonia 4-7 days from the injury

Methods: Two microdialysis catheters were placed in each patient: one in the edematous brain surrounding the focal lesion and one in the subcutaneous tissue of abdomen. Levels of vancomycin were measured in serum and in the microdialysates samples.

Results: Plasmatic concentration of 10-15 microg/ml in the trough level was obtained after four administrations of vancomycin. Levels of vancomycin in the subcutaneous tissue was above minimum inhibitory concentrations in all patients after the second administration. Mean serum/brain ratio was 8%. Cerebral interstitial concentration of vancomycin was never above minimum inhibitory concentrations; its maximum value was 1.2 microg/ml.

Conclusions: In edematous brain close to a posttraumatic hemorrhage the levels of vancomycin do not differ from that in healthy subjects. At these plasmatic concentrations cerebral interstitial levels of vancomycin were insufficient while subcutaneous interstitial levels were effective for clinical use.