Comparison of accuracy and cost of disposable, nonmechanical pumps used for epidural infusions

Background and Objectives. Temporary epidural catheter pumps are used to infuse analgesics in patients with chronic intractable pain. Three brands of disposable, nonmechanical pumps adapted for epidural infusion were tested to determine their flow rate efficacy and their cost effectiveness. Methods. Three pump models were tested: the Baxter (2C1075), Homepump (H100020), and SurgiPEACE (SP500-24). Manufacturers of each unit claim to provide a constant 2-mL/h now rate. A standard setup was used to simulate both the insertion of the catheter into the epidural space and the environmental conditions consistent with patient ambulation. Reservoirs were filled with water and allowed to infuse into a collection receptacle, and flow rates were measured hourly. Four trials were performed with four separate units and flow rate measurements were averaged to determine a now rate pattern over the entire infusion period. Data were graphed as the percentage of expected flow rate (% of 2 mL/h) versus infusion time (hours), the 90-110% range being defined as acceptable. Results. All pumps initially infused at a rate above 110% for the first 3-6 hours, after which a steady decline in now rate was observed. The Homepump produced a flow rate in the acceptable range for the greatest part of its infusion period (41%), followed by the SurgiPEACE (34%), and the Baxter unit (10.4%). The Baxter unit was also cumbersome to handle and therefore difficult to fill. The Homepump unit was easily handled but offered considerable resistance to filling, with partial loss of fluid. The SurgiPEACE unit was easy to handle and fill; however, in two of the units tested, an initial blockage was encountered, and manual patency of the connector and/or catheter had to be established. Conclusions. All three units deviated considerably from the claimed now rate of 2-mL/h, both at the beginning and at the end of the infusion. Presumably, the decreasing flow rates are responsible for the diminishing pain relief often experienced by patients over the course of the infusion. The Homepump unit appeared to be the most cost-effective and the easiest to handle and maintained an acceptable infusion rate for the greatest percentage of the infusion period. The considerable cost benefit of using a nonmechanical disposable pump as opposed to a costly but more reliable computerized pump appears to warrant further product improvement and development.