Outpatient parenteral antibiotic therapy with elastomeric pumps, what is the flowrate accuracy?

Outpatient Parenteral Antibiotic Therapy (OPAT) services have expanded throughout the world thanks to elastomeric pumps (EP). Their flowrate is known to vary by ±15%. Treatment effectiveness and the organization of care at home may be impacted, especially with piperacillin/tazobactam infusion (TAZ). An in vitro study was conducted, following the guidelines of EP and drug manufacturers, to assess the impact of three parameters on the accuracy of the infusion flowrate: composition, volume, and temperature of the infused solution.

A test bench was created to evaluate the accuracy of flowrate infusion when changing one parameter at a time (addition of TAZ in the infused solution, minimal filling volume and flow regulator at ambient temperature) compared to the standard conditions provided by the manufacturer. Two types of EP were used and connected to a weighing scale. Instantaneous and average mass flowrates over the total infusion time were determined from the reservoir mass loss. These values  were compared with the nominal flowrates announced by the manufacturers to evaluate the performance of EP under the different conditions. The time the flowrate was within the expected ±15% around the nominal flowrate was calculated as the time in range (TIR).

Deviations of the measured mean flowrate from the nominal flowrate range from -37% to 18% depending on the condition. TIR went from 0% to 80% of the total infusion duration. The test bench showed a reliability of more than 96%.

The test bench highlights differences in performance. These results raise several questions about the sensitivity of EPs for TAZ infusion in OPAT, the norm's requirements and the need to prescribe a medical device whose limits are well known, as well as therapeutic education or the course of care for treatment administration.