SYRINGE PUMPS FOR INFUSION OF VASOACTIVE DRUGS - MECHANICAL IDIOSYNCRASIES AND RECOMMENDED OPERATING PROCEDURES

Syringe pumps for vasoactive infusions have the advantages of small si ze and weight, portability, and low cost of the disposable components. However, limited syringe capacity necessitates the use of high drug c oncentrations, and the accidental delivery of even a small volume of i nfusate could seriously alter the patient's hemodynamics. To determine the circumstances under which drug delivery might be delayed, or inad vertent boluses could be delivered into the manifold, two brands of co mmercially available clinical syringe pumps were connected to a stopco ck manifold via small-bore tubing and a series of tests were performed . When the syringe pumps were operated at 3 mL/h against a closed stop cock, the pumps' occlusion alarms did not sound for 18-22 min, and whe n the stopcock subsequently was opened, 0.6-0.9 mL of infusate was del ivered as a bolus. Elevating the syringe pump by 120 cm resulted in th e delivery of up to 0.5 mL of infusate with the pump turned off. When a syringe pump operating at 6 mL/h was turned off, typically an additi onal 0.05 mL was delivered during the ensuing 2-3 min. Depending upon the method used to flush the tubing prior to use, delays in drug deliv ery of 2-3 min occurred at an infusion rate of 3 mL/h. These observati ons emphasize the need for careful equipment setup and proper use of t he manifold stopcocks to avoid unintended drug administration or delay in drug administration.