[Study on development of linear-traction type skeletal muscle powered pump]

We successfully developed Linear-Traction Type Skeletal Muscle Powered Pump (LSMPP). Unlike the Insertion-Type SMPP (ISMPP), previously used by us, in which a polyurethane chamber is inserted between skeletal muscle and chest wall, this pump can utilize the traction of muscle fiber in a linear direction. This pump also enabled us to obtain a sufficient flow with a low preload by the use of a spring for the filling of the pump. Comparison was made between the measurement of flow using the origin side of Latissimus Dorsi Muscle (o-group) (n = 6) and that using the upper arm side (i-group) (n = 6), both measured with the Linear-Traction Type equipment, and the result obtained with the ISMPP (s-group) (n = 6). Under a rate of 60 beat/min and a preload of 40 mmHg, the flows (ml/min) of o-group, i-group and s-group were 668.0 +/- 108.0, 1202 +/- 478.6 and 620.0 +/- 188.0, respectively. In i-group (n = 6), different rate, preload and spring constant were given to examine how the flow would vary with them. Mean flow (Mean +/- Std ml/min) was 815.0 +/- 378.0 at 60 beat/min, significantly different in comparison with that of 80 beat/min and that of 100 beat/min. For 40, 30 and 20 mmHg of preloads, mean flows were 877.0 +/- 366.0, 625.0 +/- 311.0 and 422.0 +/- 270.0, respectively. This showed that, as far as the rate remains low, even low preload can provide some 30% of the cardiac output of a dog as compensate cardiac flow. In contrast, there were no significant differences in mean flow with spring constants such as 0, 80, 160, 240 and 320 g/cm.