Leucocyte filtration of salvaged blood during cardiac surgery: effect on red blood cell function in concentrated blood compared with diluted blood

Objective: Leucocyte filtration of salvaged blood has been suggested to prevent patients from receiving activated leucocytes during autotransfusion in cardiac surgery. This study examines whether leucocyte filtration of salvaged blood affects the red blood cell (RBC) function and whether there is a difference between filtration of the concentrated and diluted blood on RBC function. Methods: Forty patients undergoing cardiac surgery with cardiopulmonary bypass were randomly divided into a group receiving leucocyte filtration of concentrated blood (High-Hct, n = 20) and another group receiving leucocyte filtration of the diluted blood (Low-Hct, n = 20). During operation, all the salvaged blood, as well as the residual blood, from the heart-lung machine was filtered. In the High-Hct group, blood was concentrated with a cell saver prior to filtration, whereas in the Low-Hct group, blood was filtered without concentration. RBC function was represented by RBC aggregation and deformability measured by a laser-assisted optical rotational cell analyser and by the RBC 2,3-diphosphoglycerate (2,3-DPG) and adenosine triphosphate (ATP) contents with conventional biochemical tests. Results: Leucocyte filtration of diluted blood with a tow haematocrit (14 +/- 4%) did not affect RBC function. However, when the concentrated blood with a high haematocrit (69 +/- 12%) was filtered, there was a reduction of ATP content in RBCs after passing through the filter (from 1.45 +/- 0.57 mu mol g(-1) Hb to 0.92 +/- 0.75 mu mol g(-1) Hb, p