Indirect viscosimetric method is less accurate than ektacytometry for the measurement of red blood cell deformability

Abstract

The aim of this study was to test the accuracy of viscosimetric method to estimate the red blood cell (RBC) deformability properties. Thirty-three subjects were enrolled in this study: 6 healthy subjects (AA), 11 patients with sickle cell-hemoglobin C disease (SC) and 16 patients with sickle cell anemia (SS). Two methods were used to assess RBC deformability: 1) indirect viscosimetric method and 2) ektacytometry. The indirect viscosimetric method was based on the Dintenfass equation where blood viscosity, plasma viscosity and hematocrit are measured and used to calculate an index of RBC rigidity (Tk index). The RBC deformability/rigidity of the three groups was compared using the two methods. Tk index was not different between SS and SC patients and the two groups had higher values than AA group. When ektacytometry was used, RBC deformability was lower in SS and SC groups compared to the AA group and SS and SC patients were different. Although the two measures of RBC deformability were correlated, the association was not very high. Bland and Altman analysis demonstrated a 3.25 bias suggesting a slight difference between the two methods. In addition, the limit of agreement represented 28% (>15%) of the mean values of RBC deformability, showing no interchangeability between the two methods. In conclusion, measuring RBC deformability by indirect viscosimetry is less accurate than by ektacytometry, which is considered the gold standard.

Effects of Poloxamer 188 on red blood cell membrane properties in sickle cell anaemia

“…In accordance with the literature (Vent-Schmidt et al, 2015), blood viscosity measured at an adjusted haematocrit was higher in SS than in control (AA) samples at all shear rates ( Fig 1A). While P188 treatment did not significantly affect blood viscosity in AA, it decreased blood viscosity at the three lowest shear rates in SS.…”

Integrated automated particle tracking microfluidic enables high‐throughput cell deformability cytometry for red cell disorders

“…sDI RBC curves detect subpopulations of cells that exist within bulk samples of RBCs that a simple average cell deformability cannot detect. This average value of deformability could be gauged at the bulk scale through the use of ektacytometry, but examining single cell distributions could provide information on how specific subpopulations of RBCs may cause disease complications, for example, such as vaso‐occlusive crises in SCD. It has been previously shown that patients on HU therapy exhibit lower rigidity in the RBC membrane than of those patients not on HU, albeit still lower than normal controls .…”

The role of blood rheology in sickle cell disease

“…When de-oxygenated, the sickling of RBCs causes a further rise in blood viscosity at all shear rates [8]. Plasma viscosity has also been shown to be slightly increased in SCA patients at steady state [19] likely due to the increased concentration of circulating fibrinogen and other acute phase reactant proteins.…”