Using Residual Blood from the Arterial Blood Gas Test to Perform Therapeutic Drug Monitoring of Vancomycin:An Example of Good Clinical Practice Moving towards a Sustainable Intensive Care Unit

Background. Regarding sustainability in the intensive care unit (ICU), there is increasing interest in reducing material waste and avoiding unnecessary procedures. Therapeutic drug monitoring (TDM) of vancomycin, using a dedicated tube, is standard clinical care during treatment with vancomycin. Furthermore, in the ICU, on a daily basis, arterial blood gas (ABG) tests are frequently performed throughout the day. After analysis, a variable volume of blood is discarded. Lithium heparin (LiHep) syringes for ABG tests differ from normally used dipotassium ethylenediaminetetraacetic acid (K2EDTA) tubes. The primary objective was to compare both containers and validate the use of LiHep syringes. Secondary objectives were to evaluate the potential impact on saving materials, nursing time, and costs when implementing vancomycin TDM via LiHep syringes. Methods. Vancomycin analysis from sampling in lithium heparin (LiHep) syringes for ABG tests was validated and compared with the concentrations from conventional sampling in K2EDTA tubes. For method comparison, a Bland-Altman plot and Deming regression analysis were performed. The method was validated for inter- and intra-day precision and accuracy. Vancomycin was analyzed by means of the validated method using a particle-enhanced turbidimetric inhibition immunoassay (PETINIA) autoanalyzer. Furthermore, an analysis was conducted to evaluate the potential impact of implementing vancomycin sampling via ABG tests on savings in materials, nursing time, and costs. Results. From 18 patients, 24 plasma samples in both K2EDTA tubes and LiHep syringes were obtained and compared. The mean relative difference between the two containers was -2.0% (-3.0 to -0.93%). Both the Deming regression analysis and the Bland-Altman plot met the acceptance criteria. Potentially, over 1000 blood draws and accompanying materials and packaging can be saved when vancomycin samples are obtained by means of scavenged LiHep syringe