Portable infusion pumps used for continuous regional analgesia: delivery rate accuracy and consistency

Background and Objectives: Multiple benefits of postoperative perineural local anesthetic infusion have been shown including potent analgesia, decreased opioid requirements, and improved rehabilitation. Consequently, portable infusion pumps have been used with increasing frequency to provide perineural infusion for medically unsupervised ambulatory patients. We believe that the infusion rate accuracy and reliability of these pumps infusing potentially toxic doses of medication should be investigated independently. Therefore, we studied the flow-rate accuracy and consistency of various portable infusion pumps that have not been examined previously. Methods: Using a computer/mass balance combination to record infusion rates, 6 pumps (3 electronic and 3 nonelectronic) were tested. Several factors that may influence pump performance were varied: temperature (ambient/skin), battery (replacement/addition), and catheter exchange (wound/perineural). Results: Infusion rate accuracy differed significantly among the pumps, exhibiting flow rates within ±15% of their expected rate for 55% to 99% of their infusion duration. Furthermore, the profiles (infusion rate over time) of the various pumps differed significantly depending on the pump power source. Although elastomeric pump infusion rate increased with an increase in temperature, battery life was a limiting factor for one of the electronic pumps. Substituting wound catheters with commonly used perineural catheters did not significantly alter infusion profile. Conclusions: Factors such as infusion rate accuracy and consistency, infusion profile, temperature sensitivity, and battery life affect the dose of medication administered by various portable pumps used for continuous regional analgesia. Health care providers should take these factors into consideration when choosing and using a portable infusion pump for local anesthetic administration.