Factors affecting the pulsatile hydraulic power output of the Stockert roller pump

A detailed assessment of the hydraulic power output of the Stockert roller pump was performed with the pump operating in its 'pulsatile' mode. Pressure and flow waveforms and the pulsatile power generated in a model of the human vascular bed were dependant upon the pump output, the pump control settings and the diameters of the arterial line, the pump insert and aortic cannula. The pulsatile power output was lower when a silicone rubber pump insert was used rather than a polyvinyl chloride insert. The incorporation of a Cobe CML flat-sheet membrane oxygenator into the arterial line reduced the pulsatile power to levels similar to those obtained with the pump operating in its 'continuous' mode. Incorporating a Sarns hollow fibre membrane oxygenator or a Pall extracorporeal blood filter had less effect and variations in perfusate viscosity or the length of the arterial line did not appear to have any effect. It seems probable that the experimental and clinical effects of 'pulsatile' flow during cardiopulmonary bypass with this pump will be highly dependant upon the operating conditions.

Comparison of the standard roller pump and a pulsatile centrifugal pump for extracorporeal circulation during routine coronary artery bypass grafting

The present prospective study compared the standard nonpulsatile twin roller pump with the Sarns centrifugal pump, in the pulsatile mode, as arterial pumps for extracorporeal circulation during coronary artery bypass grafting (CABG). The study was conducted in two consecutive groups of 25 patients receiving a standard anaesthetic and surgical protocol. The investigated parameters included haemodynamic profiles, oxygen exchange, blood gas and acid-base homeostasis, haematology, coagulation and complement consumption. With comparable settings for pump flow, gas flow and delivered oxygen concentrations, there was no difference between the groups in the main haemodynamic parameters during cardiopulmonary bypass (CPB). However, a tenfold lower dose of sodium nitroprusside was required to keep systemic vascular resistance within physiologic limits during CPB in the centrifugal group (C group) compared with the roller group (R group). During rewarming oxygen extraction was higher in the C group than in the R group. During the first eight hours after CPB no differences in haemodynamics, oxygenation parameters and pulmonary shunt between the groups were observed. During, as well as after, CPB there was no significant difference in blood gas and acid-base homeostasis between either group. Average postoperative blood loss via chest tubes, total transfusions of blood products, haemoglobin and coagulation did not differ between the two groups. However, the white blood cell count, corrected for changes in haematocrit, decreased during the early phase of CPB in the R group, but not in the C group.(ABSTRACT TRUNCATED AT 250 WORDS)