Effective reduction of blood cell damage by using a compliance chamber in a pulsatile extracorporeal life support system

Abstract

So far many extracorporeal life support systems (ECLS) were shown in the market, but types of their main pumps were either rotary pumps or centrifugal pumps Pulsatile pumps were usually not used due to the high hemolysis. However, pulsatile pumps have a major advantage that they are capable of synchronizing with the natural heart beat that helps to increase the coronary blood flow and decrease the load of natural heart. In this study, we tried to improve the hemolysis problem of pulsatile ECLS with a compliance chamber located between the outlet of blood pump and the inlet of membrane oxygenator. The role of the compliance chamber was simulated with a mathematical modeling of human vascular system and ECLS system. A set of animal experiment was also performed. Experimental animals were divided into 3 groups. A pulsatile pump with a compliance chamber, a pulsatile pump without a compliance chamber and a centrifugal pump without a compliance chamber were used in group 1 (6 dogs), group 2 (6 dogs) and group 3 (4 dogs) respectively. We observed the pumping capacity, gas exchange capacity and the degree of hemolysis in the acute pulmonary insufficiency animal model. After the onset of acute pulmonary insufficiency by the slow infusion of oleic acid, we started partial cardiopulmonary bypass(pCPB) and finished after 2 hrs. of pCPB. The concentration of plasma hemoglobin was measured before the animal experiments and after 2 hrs. of pCPB. We also observed several hemodynamic parameters and gas exchange parameters. The results of animal experiments show us that the hemodynamic parameters of pCPB, such as arterial pressure, central venous pressure, left atrial pressure and pulmonary capillary wedge pressure, were not significantly different among experimental groups. However, the parameters correspondent to the efficiency of gas exchange and the blood cell damage were significantly different among groups. The results of mathematical modeling also showed us that the more the amount of air in the compliance chamber, the less the fluctuation of the AoP.