title: In vivo study of flow-rate accuracy of the MedStream Programmable Infusion System.
abstract: 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 programmed 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.
  
  
  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.
authors: Codman & Shurtleff, Inc., Raynham, MA, USA.
authors: Ramakrishna
authors: R
authors: Venugopalan
authors: Alec
authors: A
authors: Ginggen
authors: Toralf
authors: T
authors: Bork
authors: William
authors: W
authors: Anderson
authors: Elaine
authors: E
authors: Buffen
mesh_terms: D000700:Analgesics / Q000008:administration & dosage / Q000627:therapeutic use; D000818:Animals; D001831:Body Temperature; D059350:Chronic Pain / Q000188:drug therapy; D006801:Humans; D015918:Infusion Pumps, Implantable / Q000592:standards*; D060186:Infusions, Spinal; D009125:Muscle Relaxants, Central / Q000008:administration & dosage / Q000627:therapeutic use; D009128:Muscle Spasticity / Q000188:drug therapy; D015203:Reproducibility of Results; D012756:Sheep
chemical_list: D000700:Analgesics; D009125:Muscle Relaxants, Central