Accuracy, continuity, and pattern of flow from five macrorate infusion pumps.

The accuracy, continuity, and pattern of flow from five commercially available macrorate infusion pumps were evaluated in vitro. Intravenous fluid was run through each infusion device at 5, 10, and 50 mL/hr. The weight of the fluid was measured serially after flow periods of 5, 10, and 15 sec for each device at each flow rate using a computerized gravimetric technique. The influence of the type of pump, flow rate, and sample-collection time on flow continuity was determined. Flow continuity (variation in flow) was expressed as the coefficient of variance of the measured weights. All of the infusion devices had flow rates within 5% of the desired rates of 5, 10, and 50 mL/hr. Flow continuity was significantly affected by the type of pump used but not by either flow rate or sample-collection time. All five devices had unique flow patterns attributable to their respective pump-operating mechanisms. The method of drug delivery and, in particular, the pump-operating mechanism of a given infusion device may affect flow continuity; therefore, alterations in clinical response to a continuous drug infusion must not be attributed exclusively to the drug or the clinical condition of the patient. Further in vitro and in vivo evaluations are needed to define the clinical importance of these data.