[Therapeutic monitoring of cerebrospinal fluid vancomycin concentrations and analysis of their influencing factors in neurosurgical intensive care unit patients].

OBJECTIVE: To evaluate cerebrospinal fluid (CSF) vancomycin concentrations and identify factors influencing CSF vancomycin concentrations in critically ill neurosurgical patients.

METHODS: A retrospective study was conducted. Adult patients who received vancomycin treatment and CSF vancomycin concentrations monitoring admitted to neurosurgical intensive care unit (ICU) of the First Affiliated Hospital of Sun Yat-sen University from January 2016 to June 2019 were enrolled. General information, vancomycin dosing regimens, CSF vancomycin concentrations, CSF drainage methods and volume of the previous day, and concurrent medications, etc. were collected for analysis. CSF vancomycin concentrations of patients with definite or indefinite central nervous system (CNS) infection, different vancomycin dosing regimens and their influencing factors were analyzed.

RESULTS: A total of 22 patients were included. 168 CSF specimens were collected for culture, 20 specimens of which were culture positive, with a positive rate of 11.9%. Sixty cases of CSF vancomycin concentration were obtained. Among the 22 patients, 7 patients (31.8%) were diagnosed with proven CNS infection, 11 patients (50.0%) clinically diagnosed, 2 patients (9.1%) diagnosed with uncertain CNS infection, and 2 patients (9.1%) diagnosed without CNS infection. Intravenous (IV) administration of vancomycin alone was used in 15 cases (25.0%), intrathecal injection in 17 cases (28.3%), IV+intrathecal injection in 23 cases (38.3%), and IV+intraventricular administration in 5 cases (8.3%). The CSF vancomycin concentrations ranged from < 0.24 to > 100 mg/L, with an average level of 14.40 (4.79, 42.34) mg/L. (1) Administration methods of vancomycin affected CSF vancomycin concentrations. The CSF vancomycin concentration with intrathecal injection or intraventricular administration was higher than that of IV administration alone [mg/L: 25.91 (11.28, 58.17) vs. 2.71 (0.54, 5.33), U = 42.000, P < 0.01]. (2) When vancomycin was administered by IV treatment alone, CSF vancomycin concentrations were low in both groups with definite CNS infection (proven+probable) and indefinite CNS infection (possible+non-infection), the CSF vancomycin concentrations of which were 4.14 (1.40, 6.36) mg/L and 1.27 (0.24, 3.33) mg/L respectively, with no significant difference (U = 11.000, P = 0.086). (3) CSF vancomycin concentrations rose with the increased dose of vancomycin delivered by intrathecal injection or intraventricular administration. According to the dose of vancomycin administered locally on the day before therapeutic drug monitoring (TDM), cases were divided into the following groups: 0-15 mg group (n = 22), 20-35 mg group (n = 33), and 40-50 mg group (n = 5), the CSF vancomycin concentrations of which were 4.14 (1.09, 8.45), 30.52 (14.31, 59.61) and 59.43 (25.51, 92.45) mg/L respectively, with significant difference (H = 33.399, P < 0.01). Moreover, the cases of CSF vancomycin concentration of ≥ 10 mg/L accounted for 18.2%, 84.8% and 100% of these three groups, respectively. CSF vancomycin concentrations mostly reached target level when dose of vancomycin administered locally were 20 mg/L or more.

CONCLUSIONS: It is difficult to reach target CSF vancomycin concentration for critically ill neurosurgical patients with or without CNS infection by IV treatment. Local administration is an effective treatment regimen to increase CSF vancomycin concentration.