OPTIMIZATION OF PRESSURE TRANSMISSION LINE CONDITON IN ELECTRICAL PNEUMATIC VENTRICULAR ASSIST DEVICE

Abstract

In most pneumatic pumps, pressure is transmitted through line which connects pressure generating system to blood sac. The previous studies have shown that characteristics of pressure transmission line are important to pump’s performance. The objective of the study is to find parameters that affect the characteristics of pressure transmission line and optimize the conditions of transmission line of electrical pneumatic VAD, HVAD which has been developed by Korea Artificial Organ Center. First of all, the following assumptions are made: (1)The transmission line is filled with compressible fluid. (2)The temperature variations are small. (3)Tube compliance is ignored. In order to optimize the condition of pressure transmission, various conditions were tested with mock circulation system. Test conditions are as follows: transmission line lengths of 0.5, 1, 2, and 4 m; transmission line diameters of 6 mm(outer diameter), 4 mm(inner diameter) and 9 mm(outer diameter), 6 mm(inner diameter); terminal volumes of 60 and 65 cc; and afterload pressures of 0,20,40,60, and 80 mmHg. Several parameters such as pump output, afterload pressure difference and pump efficiency were considered as criteria of optimization. The results have shown that the diameter and length of pressure transmission line have influences on the performance. And the performance was dependent on bellows volume and afterload conditions. From these results, optimal transmission line conditions were determined and the performance of HVAD could be enhanced by 10% with this optimization.