title: Effects of atmospheric pressure conditions on flow rate of an elastomeric infusion pump.
abstract: OBJECTIVE
  The effects of pressure conditions, both hyperbaric and hypobaric, on the flow rate of an elastomeric infusion pump were investigated.
  
  
  METHODS
  The altered pressure conditions were tested with the restrictor outlet at two different conditions: (1) at the same pressure condition as the Infusor elastomeric balloon and (2) with the outlet exposed to ambient conditions. Five different pressure conditions were tested. These included ambient pressure (98-101 kilopascals [kPa]) and test pressures controlled to be 10 or 20 kPa below or 75 or 150 kPa above the ambient pressure. A theoretical calculation based on the principles of fluid mechanics was also used to predict the pump's flow rate at various ambient conditions.
  
  
  RESULTS
  The conditions in which the Infusor elastomeric pump and restrictor outlet were at the same pressure gave rise to average flow rates within the ±10% tolerance of the calculated target flow rate of 11 mL/hr. The flow rate of the Infusor pump decreased when the pressure conditions changed from hypobaric to ambient. The flow rate increased when the pressure conditions changed from hyperbaric to ambient.
  
  
  CONCLUSIONS
  The flow rate of the Infusor elastomeric pump was not affected when the balloon reservoir and restrictor outlet were at the same pressure. The flow rate varied from 58.54% to 377.04% of the labeled flow rate when the pressure applied to the reservoir varied from 20 kPa below to 150 kPa above the pressure applied to the restrictor outlet, respectively. The maximum difference between observed flow rates and those calculated by applying fluid mechanics was 4.9%.
authors.affiliation: Baxter Healthcare, 17511 Armstrong Avenue, Irvine, CA 92614, USA. jong_wang@baxter.com
authors.forename: Jong
authors.initials: J
authors.lastname: Wang
authors.forename: Anna
authors.initials: A
authors.lastname: Moeller
authors.forename: Yuanpang Samuel
authors.initials: YS
authors.lastname: Ding
mesh_terms: D001274:Atmospheric Pressure; D020724:Elastomers; D007260:Infusion Pumps
chemical_list: D020724:Elastomers