RESUMO
Objective To find the safe vertical displacement for minimal infusion rate change of syringe pumps as the theoretical guidance for moving pumps. Methods The infusion volume within 1 minute after none and vertically moving 15, 25, 35, 50 cm of the pumps (microinfusion pump WZ-50C、WZ-50C2、BRAUN perfusor compact) at 10 ml/min were weighted and compared by the electronic balance. Results Significant differences of the infusion rate were detected. The difference of average infusion volume within 1 minute after vertically moving 15, 25, 35, 50 cm and non-movement were 0.004 (minimal),0.017, 0.033, 0.046ml. The lowest infusion curve of 15cm displacement stretches slightly above the horizontal plane until the inflexion in the section graph, leading to steeper in accordance with the increasing vertical displacement of the pumps,which implied the following drastic increase in infusion rate. Conclusions The minimal infusion change is obtained at 15cm, thus becomes the safe displacement height and the inflexion point of further soaring changes.