For infants, pump output flow rate should be controlled accurately, especially in low perfusion rate and not decrease at high pulse rate. Stroke volume of an air driven pump which we developed is varied with driving conditions (pulse rate, load pressure, etc.), so that it is difficult to control pump output flow rate precisely. Considering all possible items requiring to a pump for an application to an infant, we developed a pulsatile roller pump driven by a stepping motor. Employing a microcomputer for the sequential control of revolution of the stepping motor, stroke volume is able to change intentionally and controlled accurately. Moreover the pump output flow does not decrease at high pulse rate. To confirm these advantages experimentally, pump output was examined using over flow tank system. These results were as follows;
1) Changing the pulse rate from 60 to 300 [ppm] at pre-load press. :20 [mmHg] and after load press. : 80 [mmHg], the deviation of the pump flow rate was only 3.4 [%] at 500 [mL/min] and 4.2[%] at 1000 [mL/min].
2) At pulse rate 100 [ppm] and preset flow rate 500 [mL/min], the fluctuation of the flow rate was 1.6 [%] by changing pre-load from 5 to 30 [mmHg], and 1.6 [%] by changing after load from 50 to 110 [mmHg].
The pump flow rate is able to control so accurately without any feedback system that this pulsatile roller pump is suitable for pediatric surgery.
