Clinical research for trough value of serum vancomycin in critical patients

Abstract

To observe the changes in serum vancomycin trough concentration, and explore its optimal dosage in critical patients. A retrospective study was conducted. Data of 66 patients who used vancomycin during July 2010 to May 2012 in surgical intensive care unit (SICU) of the First Affiliated Hospital of Sun Yat-Sen University were collected and analyzed. According to the endogenous creatinine clearance rate (CCr), the patients were divided into two groups: CCr normal group (≥70 mL/min) and CCr lowered group (<70 mL/min). The distribution of vancomycin serum trough concentration between two groups, relationship between vancomycin serum trough concentrations and CCr, and the influence of vancomycin serum trough concentrations on the prognosis was analyzed. The difference between actual dosage and the recommended dosage in guideline was compared between two groups. 119 times of vancomycin serum trough concentration in 66 patients were enrolled, and it was found that only 20.17% (24/119) reached the target concentration (15-20 mg/L), 45.38% (54/119)<15 mg/L and 34.45% (41/119) >20 mg/L. Vancomycin serum trough concentration in CCr normal group (55 cases) was (13.11±6.84) mg/L, among them 65.5% (36/55) attained lower trough concentrations (<15 mg/L). In the subgroup with 15-20 mg/L trough serum concentrations, vancomycin doses were significantly lower than that of recommendation (1.95±0.61 g/d vs. 2.73±0.32 g/d, F=1.739, P=0.001). Vancomycin serum trough concentration in CCr lowered group (64 cases) was (20.49±8.12) mg/L, with 51.5% (33/64) of them showed higher trough concentrations (>20 mg/L). In the subgroup with 15-20 mg/L vancomycin trough serum concentration, vancomycin doses were higher than that of recommendation (1.08±0.49 g/d vs. 0.78±0.19 g/d, F=11.294, P=0.062). There was no significant difference in 28-day mortality between patients with targeting trough serum concentrations and those without [22.2% (4/18) vs. 18.8% (9/48), χ(2)=0.009, P=0.924]. Serum creatinine [odds ratio (OR)=1.001, 95% confidence interval (95%CI): 0.990-1.012, P=0.000], vancomycin doses (OR=0.600, 95%CI: 0.251-1.434, P=0.003), age (OR=0.985, 95%CI: 0.955-1.015, P=0.015) and body mass index (OR=1.013, 95%CI: 0.967-1.062, P=0.022) were found to be correlated to serum trough concentrations by multiple linear regression analysis. The rate of vancomycin serum trough concentrations reaching the standard is low in critical patients, so constant monitoring is necessary. Creatinine, vancomycin dosage, age and body mass index show a relatively significant influence on the serum trough concentrations, and they should be taken into consideration in dosage to be given.