FLUCTUATIONS IN SYRINGE-PUMP INFUSIONS - ASSOCIATION WITH BLOOD-PRESSURE VARIATIONS IN INFANTS

Flow continuity of two brands of syringe pumps and four brands of syri nges was studied as a possible cause of hemodynamic fluctuations obser ved in neonates.Cyclical fluctuations were observed in the blood press ure of 14 neonates receiving dopamine infusions by syringe pump at flo w rates from 0.2 to 1 mL/hr. Atom 235 and IVAC 770 pumps and various s izes of Terumo, Becton Dickinson, Omnifix, and IVAC syringes were eval uated. Flow continuity was assessed by using a gravimetric technique. The force needed to initiate and maintain syringe plunger motion was a lso measured. Noncontinuous flow was encountered most commonly with Te mmo syringes, which delivered boluses at regular intervals at flow rat es up to 5 ml/hr. The interval was dependent on flow rate and was simi lar to the time between the blood pressure fluctuations observed clini cally. The syringe plunger force exhibited regular fluctuations indica tive of the plunger sticking, and simultaneous measurement of flow est ablished a direct temporal relationship with boluses. The other syring es tested did not exhibit such fluctuations. No differences were found between the two syringe pumps. Syringe plunger sticking, resulting in intermittent boluses and potential blood pressure fluctuations, may o ccur at low flow rates and with certain syringe brands. This appeared to be the cause of hemodynamic fluctuations in neonates receiving dopa mine infusions.