Changes in Whole Blood Viscosity at Low Shear Rates Correlate with Intravascular Volume Changes during Hemodialysis

Abstract

Elevated blood viscosity has been shown to be independently correlated with cardiovascular risk factors and associated with increased risk of major cardiovascular events, including death and acute myocardial infarction. The aim of the present study was to investigate changes in whole blood viscosity (WBV) at shear rates of 1, 5, and 300 s-1 before and after hemodialysis in patients with end-stage renal disease (ESRD). We also examined the relationship between the changes of WBV and intravascular blood volume. 43 patients with ESRD receiving maintenance hemodialysis were enrolled. WBV was measured using a scanning capillary tube viscometer pre- and post-dialysis to quantify dialytic viscosity surges. Body weight, blood pressure, and hematocrit were also measured before and after hemodialysis, as was the fluid removed during the session. Hemodialysis had a 3 times greater impact on the low-shear WBV at a shear rate of 1 s-1 (i.e., 44.1% change) than on the high-shear WBV at a shear rate of 300 s-1 (i.e., 15.9% change). Changes in the low-shear WBV obtained at shear rates of 1 and 5 s-1 during hemodialysis were significantly correlated with changes in hematocrit. The intravascular blood volume reduction during hemodialysis was positively correlated with the changes in both high-shear and low-shear WBVs. These results suggest that the WBV parameter may hold additional information beyond hemoconcentration. Further research is needed to evaluate the relationship between low-shear WBV surges and increased morbidity in the patient population with ESRD.