The Roller Pump Does Produce Pulsatile Flow

(J. Extra-Corpor. Technol. 19[3] p. 376-383 Fall 1987, 15 ref.) This study was undertaken to investigate, under experimental conditions, the nature of the roller pump output. Pressure and flow studies were done on 200° roller pumps using PVC and silastic formulations in the raceway. Polyvinyl chloride (PVC) tubing in all sizes produced comparatively higher pressure levels with narrow pressure spikes. Small bore tubing with high revolutions per minute (RPMs) delivered characteristic pulseless flow due to telescoping of flow and pressure pulses. Large bore PVC tubing produced pulsatile flow curves with spikes, ripples and artifacts. Silastic and fluorocarbon tubing achieves pulsatile flow curves without ripples or artifacts at a comparatively lower pressure range. A wide pulse width and a single roller ripple chararacterize it. Ideal combinations used clinically in over 1,500 cases result in appreciable pulse flow measurable in significant changes in renal output both in normothermic and hypothermic conditions. These results show that a regular roller pump, with the use of tubing with specific viscoelastic properties and the proper choice of stroke volume, will produce a significant level of pulsatile flow. There is no need for an add-on system. Preliminary work utilizing a single roller pump, as a means of enhancing the pulse wave, is presented. Techniques to remove the 200° single roller induced ripple is also discussed.