Hemodynamic Energy Delivery of the Pulsatile Flow in a Simulated Pediatric Extracorporeal Circuit

Abstract

Objectives of this study were 1) to precisely measure the generation and delivery of hemodynamic energy levels during pediatric cardiopulmonary bypass procedure using a simulated circuit and 2) to quantify energy losses of the extracorporeal circuit components. A conventional roller pump, pediatric hollow-fiber membrane oxygenator, arterial filter, arterial cannula, and (1/4)-in tubing were used. The circuit was primed with 40/60 glycerin/water mixture. Postcannula (pseudo patient's pressure) pressure was maintained 40 mm Hg by a Hoffman clamp. All trials were conducted at 800 mL/min of pump flow with pulsatile (n=6) and nonpulsatile (n=6) modes at room temperature. Simultaneous blood flow and pressures at pre/post oxygenator and pre/post cannula sites were recorded. There were gradual decreases in values of circuit mean pressure, energy equivalent pressure, surplus hemodynamic energy, and total hemodynamic energy (THE) from pre- and postoxygenator to pre- and postcannula sites. Approximately 30% of THE generated by roller pump was damped by the membrane oxygenator. About 25% of THE was lost by the arterial filter and the length of the arterial tubing. Only 15%-18% of THE was delivered into the pseudo patient. Although the results of this study showed that the roller pump could provide higher hemodynamic energy per second with pulsatile flow compared with the nonpulsatile flow, the majority (80%) of hemodynamic energy was damped by the components of the extracorporeal circuit.