Leukocyte depletion during cardiac operation: A new approach through the venous bypass circuit

Background. Leukocyte depletion recently has been introduced for cardiac surgical patients to attenuate leukocyte-mediated inflammation and organ reperfusion injury. We evaluated the feasibility of a new leukocyte depletion method in which systemic leukocyte depletion is achieved through the venous side of the cardiopulmonary bypass circuit under low blood flow.

Methods. Forty cardiac surgical patients undergoing cardiopulmonary bypass were allocated randomly to a leukocyte depletion group (n = 20) and a control group (n = 20). In the depletion group, leukocyte filtration was achieved with two filter sets located between the venous drainage and the venous reservoir, Leukocyte filtration was commenced after the start of rewarming but before the release of the aortic cross-clamp, and it was driven by a spare roller pump of the heart-lung machine.

Results. All the episodes of filtration went smoothly within a period of 10 minutes and with a blood now rate of 400 mL/min. The mean leukocyte removal rate calculated at the end of filtration was 69%. Circulating leukocytes were reduced by 38% in the depletion group compared with the control group at the moment of crossclamp release (4.3 x 10(9)/L versus 6.8 x 10(9)/L, p <0.05). The postoperative inflammatory response also was reduced as indicated by less production of interleukin-8 (p <0.05). Clinically, there was no significant difference between the two groups in postoperative Pao(2) or pulmonary hemodynamics.

Conclusions. It is technically feasible to deplete circulating leukocytes through the venous side of the cardiopulmonary bypass-circuit with a low blood now rate. Future studies should focus on the duration and timing of leukocyte depletion to optimize the methodology of leukocyte depletion for cardiac surgical patients. (Ann Thorac Surg 1999;67:604-9) (C) 1999 by The Society of Thoracic Surgeons.