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°C and 1013 mBar (80 flow intervals). Results: In vivo (sheep body temperatures 38.1°C–39.8°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°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.