Variations of whole blood viscosity using Rheolog™—a new scanning capillary viscometer

Abstract Background : Whole blood viscosity (WBV) values identify subjects at high risk for initial or recurrent cardiovascular events. However, these measurements have been limited to specialized centers. A new type of viscometer, Rheolog™, was designed to overcome the difficulties encountered in WBV measurements using the standard rotational viscometer in a clinical environment. Methods : We evaluated the 14-day variability of WBV measured by Rheolog™ in a single-center study of 24 healthy male subjects aged 18–75 years. WBV was measured through an 11-h period on study days 1, 8, and 14. An additional fasting WBV test was performed on study days 3, 5, and 11. Results : Average morning measurements were higher than afternoon measurements at all shear rates. Both inter- and intraindividual variations were higher in the morning than later in the day, but the differences between pooled mean values were not significant. Interindividual variations at fasting were higher than the pre-meal or overall variations. There was a small nonsignificant increase in mean viscosity following each meal. Conclusion : WBV measurements using Rheolog™ have potential for clinical application because of the convenience and low variability of measurements over time.