Miniaturized cardiopulmonary bypass: Marginal impact on inflammation and coagulation but loss of safety margins

Objective: Inflammation and coagulation disturbances are common consequences of cardiopulmonary bypass (CPB). Recently, miniaturized, closed CPB circuits without cardiotomy suction and venous reservoir have been proposed to reduce complication rates. We compared outcomes with conventional (CCPB) and miniaturized cardiopulmonary bypass (mini-CPB) after coronary artery bypass operations (CABG) with respect to inflammation and coagulation.

Methods: Twenty patients (25% female, age 68.3+9.0 years) were prospectively randomised to undergo isolated CABG with CCPB or mini-CPB. CCPB had a pump prime of 1600ml. Mini-CPB consisted of a centrifugal pump, arterial filter, heparinized (Cameda; Medtronic Inc.) tubing and oxygenator with a priming volume of 800ml. Shed blood was removed by a cellsaver device and reinfused. Measurements included IL-2 receptor, IL-6, IL-10, TNF receptor 55 and 75, CRP, leukocyte differentiation, INR, PTT, d-dimeres, fibrinogen, thrombocytes at six time points.

Results: In both groups no major complication occurred. However, operative handling was more difficult in the mini-CPB group due to limitations in venting and fluid management. Repeated measures analysis revealed that not a single parameter of inflammation, coagulation, or clinical outcome showed significant differences among groups. Blood loss tended to be lower in the mini-CPB group with 519±230ml vs. 686±386ml (p=0.33); however mini-CPB patients received more red blood cells (1.88±1.69 vs. 0.625±1.32 units; p=0.14) and fresh frozen plasma (0.75±1.30 vs. 0.375±0.99 units; p=0.55).

Conclusion: Use of a mini-CPB affected inflammation and coagulation parameters only marginal and did not lead to clinical relevant changes as assessed by blood loss, need for blood products, ICU and clinical stay. However, safety margins for volume loss, air emboli, and weaning from CPB decrease, because of the closed mini-CPB circuit.