Delivery rate accuracy of portable, bolus-capable infusion pumps used for patient-controlled continuous regional analgesia

Background and Objectives: Portable patient-controlled pumps used for perineural local anesthetic infusion appear to be gaining acceptance and are used for an increasing number of medically unsupervised ambulatory patients. The infusion rate accuracy and reliability of these pumps, which allow patient-controlled boluses of potentially toxic medication, has not been independently investigated. We performed this laboratory study to define the flow-rate accuracy, reliability, and profiles of various portable bolus-capable infusion pumps and varied several factors that may influence pump performance. Methods: Using a computer/scale combination, 4 electronic pumps were tested with 1 and 2 sets of batteries over 100 hours. One elastomeric pump was tested with its flow-regulator at room temperature (20°C to 24°C), skin temperature (32°C), and increased temperature (36°C). The elastomeric pump was also tested by varying the height of the pump relative to the distal end of the catheter. Results: Infusion rate accuracy differed significantly among the pumps, exhibiting flow rates within ±15% of their expected rate for 29% to 100% of their infusion duration. Changing the batteries after 50 hours affected the profile of 1 of the 4 electronic pumps. For the elastomeric pump, an increase in temperature significantly increased the infusion rate. An increase or decrease in pump-to-scale height significantly increased or decreased the infusion rate, respectively. Conclusions: These results suggest that factors such as flow-rate accuracy and consistency, infusion profile, and temperature sensitivity should be taken into consideration when choosing a portable infusion pump for local anesthetic administration. Reg Anesth Pain Med 2003;28:17-23.