Flow rate accuracy of ambulatory elastomeric and electronic infusion pumps when exposed to height and back pressures experienced during home infusion therapy

Background: Elastomeric infusion pumps are widely used in the delivery of parenteral medications in the home, but real-life conditions may not match calibration or standardised testing conditions. This study investigated the impact of changes in infusion pump height and/or back pressure on infusion pump function. Methods: Volume delivered after one day, infusion duration, average and peak flow rates and time spent within stated accuracy were determined for four elastomeric and one electronic pump using gravimetric technique. Experiments were repeated after altering the height of the pump relative to the output (+/- 40cm, +/- 20cm) and/or adding a back pressure (10-30mmHg) to the output of an attached catheter. Results: Under ideal operating conditions, the flow rate deviated from that specified by the manufacturer and between 88.5% and 99% of the total infusion volume was delivered. Varying the height or applying back pressure led to further changes in average flow rates and the volume of infusion solution delivered by the elastomeric pumps, but had little effect on the electronic pump. Conclusions: Clinicians should consider potential impact on drug delivery, safety and therapeutic effect for home infusion patients given variations in infusion pump performance observed in this study.