Decreased flow accuracy from volumetric infusion pumps.

Accurate flow from infusion pumps should be maintained when exposed to a variety of clinical conditions. The intent of this study was to evaluate in vitro flow rate accuracy of three infusion pumps subjected to the influences of variable back-pressure, solution viscosity, and infusion rates. A factorial study design was selected to determine the influence of three flow rates (5, 10, and 20 ml/h), three back-pressures (100, 200, and 300 mm Hg), and two solution viscosities (5%, 25% dextrose in water) on flow rate accuracy from three infusion pumps (Abbott 4P, IVAC 560, and Travenol 6200) using a standard gravimetric technique. Mean +/- SD accuracy values were -9.4 +/- 6.4% (range -29.1 to -0.7), 0.5 +/- 2.2% (range -4.2 to 6.3), and -0.5 +/- 4.7% (range -8.5 to 9.9) of the desired rate for the Abbott, IVAC, and Travenol devices, respectively. Back-pressure was the only factor to influence significantly flow accuracy for the Abbott device (r = .81). All factors significantly influenced accuracy for the Travenol device (r = .55). No factor influenced accuracy for the IVAC infusion pump. Both the IVAC 560 and Travenol 6200 have acceptable flow accuracy values within the range of study factors examined. The Abbott 4P had significant decreases in flow accuracy in response to increasing back-pressure.

Flow rate variability from selected syringe and mobile infusion pumps.

Alterations in response to pharmacological agents have been attributed to flow rate variation produced by intravenous infusion devices during drug delivery. A wide range of variation has been shown to occur with large-volume infusion devices. The intent of this investigation was to examine flow variation resulting from the use of selected small-volume syringe and mobile infusion devices and determine whether these devices have greater flow continuity than large-volume infusion pumps. Each syringe and mobile infusion device delivered iv fluid at three flow rates (1, 5, and 10 ml/h). The effusate was collected in a tared beaker and serial weights were measured every ten seconds using a computerized, gravimetric technique. Accuracy, continuity, and pattern of flow were determined for each of the syringe and mobile infusion devices. All of the devices produced accurate flow, within +/- 10 percent of the desired 5 and 10 ml/h rates. However, the actual iv flow rate ranged from 53 to 93 percent for the 1 ml/h rate. Continuity and pattern of flow resulting from each device were diverse. When compared with large-volume, microrate infusion devices, no significant differences could be observed. Therefore, no clear advantage to delivering drug solutions on a continuous basis can be expected from the use of small-volume devices. Specific infusion devices may be preferable for certain clinical applications; flow continuity data may be valuable when selecting an infusion device.

Flow rate variability from electronic infusion devices.

During continuous drug administration to pediatric patients, unfavorable pharmacologic effects have occurred. These effects were attributed to variations in flow from electronic infusion devices (EIDs). The intent of this investigation was to evaluate the influence of microrate (0.1 to 99.9 ml/h) EID on the accuracy, continuity, and pattern of flow of continuously effused fluid. Using a factorial study design, iv fluid was effused through iv delivery systems using combinations of five microrate EIDs, three iv flow rates, and three sample-collection intervals. Serial weights were measured at the appropriate sample-collection time using a computerized gravimetric technique to determine accuracy, continuity, and pattern of flow. All the EIDs produced accurate flow within 5% of the desired rate of 5 and 10 ml/h. At 1 ml/h, the actual iv flow rate ranged from 65.1% to 91% of the desired rate. Each of the respective EIDs produced various levels of flow continuity; each flow pattern characterized the mechanism of pump operation for each device. Thus, alteration in response (e.g., increased toxicity or decreased efficacy) to a continuous drug infusion must not be attributed exclusively to the drug or clinical condition of the patient. Serious consideration should also be given to the method of drug delivery and, in particular, the continuity of flow that results from a particular EID.

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.