Background and Objective: Prerequisite for oxygen transport to the tissue is the ability of erythrocytes to change from a discoid into an elongated form in order to pass microvessels. Cell salvage is highly recommended to decrease blood loss and to avoid allogeneic transfusions in perioperative bleeding. The purpose of our study was to assess deformability of erythrocytes at re-transfusion.
Materials and Methods: After ethics committee approval and informed consent, blood was withdrawn from the autotransfusion system (Xtra, Sorin, Germany) of 24 patients undergoing joint arthroplasty 6 hours after cell salvage initiation. Deformability curves, elongation indices (EI) obtained at increasing shear stress (SS) were assessed by using Laser Optical Rotational Red Cell Analysis (LORRCA).
Results: Erythrocytes showed the typical sigmoid EI/SS curve with a mean maximum elongation index (EImax) of 0.593 ± 0.034 and mean half-maximal deformation (SS ½) of 1.186 ± 0.387 Pa. Irregular curve shapes and high variability in EI occurred at shear stress < 3 Pa. Recalculation of outcome parameters resulted in higher values (EImax 0.610 ± 0.035; SS ½ 1.562 ± 0.346 Pa).
Conclusion: Erythrocytes after autologous cell salvage are not stiff but elongate in response to shear stress. Erythrocytes showed the typical EI/SS-curve of human red cells, which indicates that the cells are able to uptake the hydrodynamic forces that act on them during the measurement. Further research is needed to investigate the effect of cell salvage processing on erythrocytes from patients with pre-existing hematological disorders.
Assessing the Vascular Deformability of Erythrocytes and Leukocytes: From Micropipettes to Microfluidics
