In a somewhat different process, autologous blood can be diverted from a patient to a hemodialysis device (artificial kidney) or a heart-lung pump. The blood flows out through a tube to the artificial organ that pumps and filters (or oxygenates) it, and then it returns to the patient’s circulatory system. Some Christians have permitted this if the equipment is not primed with stored blood. They have viewed the external tubing as elongating their circulatory system so that blood might pass through an artificial organ. They have felt that the blood in this closed circuit was still part of them and did not need to be ‘poured out.’a

What, though, if the flow of such autologous blood stopped briefly, such as if a heart-lung machine is shut down while the surgeon checks the integrity of coronary-bypass grafts?

Actually, the Biblical emphasis is not on the issue of continuous flow. Even aside from surgery, a person’s heart might stop briefly and then resume.b His circulatory system would not have to be emptied and his blood disposed of just because blood flow had stopped during the cardiac arrest. Hence, a Christian having to decide whether to permit his blood to be diverted through some external device ought to focus, not primarily on whether a brief interruption in flow might occur, but on whether he conscientiously felt that the diverted blood would still be part of his circulatory system.​—Galatians 6:5.

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With a heart-lung device, the circuit includes: (1) tubing from patient’s vascular system; (2) recovery suction pumps; (3) bubble oxygenator; (4) hollow-fiber hemofilter; (5) main roller pump; (6) return line to patient’s circulatory system