A study of leucocyte removal by the RemoweLL cardiotomy reservoir.

Background: Cerebral damage is a relatively frequent complication of cardiopulmonary perfusion. Leucocyte activation and lipid microembolisation are among the possible causes. The removal of leucocytes and lipid microparticles from the cardiotomy suction blood could prevent this complication.

Methods: We studied the properties of a cardiotomy reservoir (RemoweLL, EUROSETS), which contains a filtering layer designed to remove some leucocytes and lipid microparticles. The reservoir was loaded with red cell concentrates or whole blood units, some of them containing hyperlipidaemic plasma. The extent of leucocyte and lipid removal was evaluated with reference to the storage age and pre-filtration absolute values of the products.

Results: On average, the cardiotomy reservoir removed 35-39% of total leucocytes, with a slight preference for neutrophil granulocytes. This device also retained 26-30% of platelets. The efficiency was not influenced by the storage age of the filtered product nor by the total cell load, within the explored range (323x10(6) - 1,345 x10(6) total leucocytes). Lipid (cholesterol, triglycerides) removal was minimal (about 3-6%).

Discussion: The RemoweLL device removed more than a third of the leucocytes from the processed blood. Lipid removal was minimal but the lipid particles in our model (chylomicrons) have a diameter 100-fold smaller than the particles believed to be responsible for clinical effects. This device seems promising and worthy of further studies to document the saturation point of leucocyte removal. On the other hand, lipid removal should be studied in a model more closely resembling the clinical situation in which the device is expected to be used.