A recent study aimed to assess the extent of IV antimicrobial drug loss in infusion lines. Using a hypothetical patient case–based scenario, investigators set out to determine the percentage of antimicrobial drug loss if IV lines are not flushed. The hypothetical patient, a 50-year-old male patient weighing 70 kg with an estimated creatinine clearance of >90 mL/min, was utilized to determine the degree of drug loss.
Two IV administration sets were studied—Intrafix Safeset, a gravity drip infusion set that is 180 cm long and is available in Europe, and Volumat VL ST 02, which is a 235-cm-long IV administration set designed for use with rate-controlling infusion pumps that is available in the United States. (The Intrafix Safeset will not be discussed further due to its lack of availability in the U.S.) Residual volumes following the administration of 39 IV antimicrobial agents to the hypothetical patient were obtained in-house based on an average of three measurements. Product labeling was used to assess the length of infusion.
As this study was conducted in the United Kingdom, the National Health Services (NHS) Injectable Medications Guide was used for information on reconstitution, dilution, and displacement values to calculate infusion volumes and concentrations. Drug loss was calculated in milligrams and then converted into the percentage of drug loss based on concentration values and the average residual volume in the infusion line.
The investigators found that the average residual volume was 15.83 mL (range: 15.06-16.47 mL) for the Volumat VL ST 02 administration set. Drug loss ranged from four IV antimicrobial agents in which >25% of the drug was lost up to four drugs in which only 0%-5% of drug loss occurred; for 15 IV anti-infectives, an 11% to 15% loss of the antimicrobial agent was observed.
Analysis of the individual IV antimicrobial agents showed that for the Volumat VL ST 02 administration set, the drugs with the highest residual volumes were daptomycin (dose 420 mg at a concentration of 7.19 mg/mL) at 27% drug loss; ertapenem (dose 1 gram at a concentration of 16.67 mg/mL) and ceftazidime (dose 2 g at a concentration of 33.33 mg/mL), each with 26% drug loss; and ceftriaxone (dose 2 g at a concentration of 28.57 mg/ mL), which was associated with 23% drug loss.
While the findings were concerning and were higher than initially anticipated, the authors cautioned that individual provider technique or manipulation of the infusion set can contribute to variability in the findings. They recommend that to obtain more definitive results, a larger cohort study is needed. Further, dosages were standardized for a hypothetical patient and do not take into account variations in drug-dose adjustment, infusion-volume variations, extremes of body weight, alterations in renal function, fluid-restricted states, or severity of infection, which may require higher doses. This study was conducted in the United Kingdom, and the authors asked the NHS to call upon healthcare organizations to review their IV infusion administration-sets flushing policy.
Pharmacists should educate nurses on the importance of consistently flushing IV lines, especially during the administration of antimicrobial agents, as drug loss secondary to residual volumes can lead to lack of attainment of minimum inhibitory concentrations, prolonged time to required serum levels, and clinical deterioration.
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