In vivo study of flow-rate accuracy of the MedStream Programmable Infusion System.

Objective: Flow-rate accuracy and precision are important parameters to optimizing the efficacy of programmable intrathecal (IT) infusion pump delivery systems. Current programmable IT pumps are accurate within +/- 14.5% of their programed infusion rate when assessed under ideal environmental conditions and specific flow-rate settings in vitro. We assessed the flow-rate accuracy of a novel programmable pump system across its entire flow-rate range under typical conditions in sheep (in vivo) and nominal conditions in vitro. Materials and Methods: The flow-rate accuracy of the MedStream Programmable Pump was assessed in both the in vivo and in vitro settings. In vivo flow-rate accuracy was assessed in 16 sheep at various flow-rates (producing 90 flow intervals) more than 90 +/- 3 days. Pumps were then explanted, re-sterilized and in vitro flow-rate accuracy was assessed at 37 degrees C and 1013 mBar (80 flow intervals). Results: In vivo (sheep body temperatures 38.1 degrees C-39.8 degrees C), mean +/- SD flow-rate error was 9.32% +/- 9.27% and mean +/- SD leak-rate was 0.028 +/- 0.08 mL/day. Following explantation, mean in vitro flow-rate error and leak-rate were -1.05% +/- 2.55% and 0.003 +/- 0.004 mL/day (37 degrees C, 1013 mBar), respectively. Conclusions: The MedStream Programmable Pump demonstrated high flow-rate accuracy when tested in vivo and in vitro at normal body temperature and environmental pressure as well as when tested in vivo at variable sheep body temperature. The flow-rate accuracy of the MedStream Programmable Pump across its flow-rate range, compares favorably to the accuracy of current clinically utilized programmable IT infusion pumps reported at specific flow-rate settings and conditions.