BLOOD_VOLUME_SERVO

Published:2009/7/17 5:19:00 Author:Jessie | From:SeekIC

Servo-controlled pump with variable stroke drives blood from venous system of patient into artificial lung and after oxygenation returns it to arterial system. Control circuit insures that volume of blood is constant. Sensor is brass disk forming capacitance with pool of blood in oxygenator at spacing of 1mm. Error signal derived +tom capacitance change unbalances bridge that is energized at 3 kc (points B-B).Amplified error signal is applied to phase-sensitive demodulator. Unbalance energizes center-stable relays K1 and K2 of arterial and venous servo motors, so stroke output of arterial pump is decreased while that of venous pump is increased, or vice versa, to restore preselected volume of blood.-R. Schild and N. Wesson, Servo Circuit Controls Artificial Heart, Electronics, 31:15, p 73-75.



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