Abstract ID: A21
Abstract Title: New Portable Infusion Pumps: Infusion Rate Accuracy and Consistency
Poster Type: Discussion
ABSTRACT BODY
Introduction: Portable infusion pumps are being used with increasing frequency to provide perineural,1 direct wound,2 and intraarticular3 local anesthetic infusion for medically unsupervised ambulatory patients. The infusion rate accuracy, reliability and characteristics of multiple pumps have been previously described.4-6 However, a number of new pump models have recently become available. We believe that devices infusing potentially toxic doses of medication should be independently investigated. Therefore, we studied the flow-rate accuracy and consistency of various portable infusion pumps that have not been previously examined.
Methods: Using a computer/ mass balance combination to record infusion rates, six pumps were investigated (Table 1). Each pump was tested twice with a new unit set at 5 mL/hr using normal saline as the infusate. If the infusion rate during the second trial was found to differ more than ±10% of the original trial at any point, then a third trial was performed. The trials were combined to produce a mean profile for each pump. The nonelectronic devices were tested with their flow-regulators at various temperatures to determine this effect of this variable on infusion rate and profile. In addition, one nonelectronic pump (I-Flow) is marketed as a 400 mL unit, but manufacturer instructions indicate that overfilling the anesthetic reservoir to 500 mL is acceptable to lengthen infusion duration. Therefore, this unit was tested at both 400 and 500 mL to determine the relationship between reservoir volume and infusion rate/profile.
Results: See Figures 1 and 2.
Conclusion: The relatively new electronic infusion pumps provided very consistent flow rate accuracy and consistency, with two of the four models providing infusion for up to 150 hr. Of the new nonelectronic, elastomeric pumps, flow-rate accuracy varied with temperature and reservoir volume. These results suggest that factors such as flow-rate accuracy and consistency, infusion profile, temperature sensitivity, and desired infusion duration should be taken into consideration when choosing and utilizing a portable infusion pump for local anesthetic administration.
References:
1. Rawal et al. Anesthesiology 2002; 96: 1290-6
2. Savoie et al. Arthroscopy 2000; 16: 339-42
3. Klein et al. Anesth Analg 2001; 93: 601-5
4. Ilfeld et al. Anesth.Analg. 2002; 95: 1331-6
5. Ilfeld et al. Reg Anesth Pain Med. 2003; 28: 17-23
6. Ilfeld et al. Reg Anesth Pain Med 2003; 28: 424-32
ATTACHED FILES
A21_Table 1.pdf
A21_Figure 1.ppt
A21_Figure 2.ppt
Reg Anesth Pain Med 2004; 29(2):A21