Objective: To compare the relationship between variability in nitroprusside delivery from five infusion pumps and the resulting variability in mean arterial pressure (MAP). Design: Randomized, crossover study design. Setting: A pediatric ICU in a university hospital. Patients: Informed parental consent was obtained for six patients who were hemodynamically stable and receiving a continuous nitroprusside infusion for a clinical application. Subjects ranged in age from 11 months to 9 yr. Interventions: All of the subjects were administered nitroprusside using selected infusion pumps, which included Abbott (Micro), 3M/AVI (210), IMED (965), IVAC (565), and Kendall McGaw (MicroRate). Measurements and Main Results: After an initial equilibration interval for each device, MAP was measured and recorded at 10-sec intervals for greater-than-or-equal-to 90-min intervals using a computerized data collection technique. Variation in nitroprusside administration (flow continuity) for each infusion pump was determined in vitro using a computerized gravimetric technique. Variation in both MAP and flow continuity was mathematically expressed as the coefficient of variance (CV) of the measured values for each of the respective infusion pumps. For the Abbott, IMED, 3M/AVI, IVAC, and Kendall McGaw infusion pumps, mean +/- SD continuity CV values were 85 +/- 31%, 39 +/- 26%, 19 +/- 8%, 17 +/- 3%, and 12 +/- 3%, respectively, and MAP CV values were 18 +/- 21%, 15 +/- 11%, 8 +/- 2%, and 16 +/- 10%, respectively. Conclusions: An apparent direct relationship between MAP variability and flow continuity was observed. We speculate that variation in effect of potent short-acting drugs may, in part, be due to infusion pump operation.
