Methods in clinical hemorheology: The continuous measurement of arterial blood density and blood sound speed in man
Issue title: The Seventh International Congress of Biorheology. Part II, Clinical Hemorheology. Held at Palais des Congrès, Nancy, France, 18–23 June 1989
Guest editors: Alfred L. Copley and Jean-François Stoltz
Affiliations: [a] Department of Physiology, Karl Franzens University Graz, A-8010 Graz | [b] Department of Surgery, Karl Franzens University Graz, A-8010 Graz | [c] Wilhelm Pieck University Rostock, GDR-2500 Rostock-1 | [d] Department of Medicine, Karl Franzens University Graz, A-8010 Graz
Note: [] Accepted by: Editor-in-Chief S. Witte
Abstract: Both blood density and sound speed are closely related to total protein concentration in blood and, as a consequence, to rheologically important parameters of blood. Two methods that permit continuous measurement of these properties, the mechanical oscillator technique and the new ultrasonic technique, were used for measuring blood protein concentration over a continuous period of time in a group of hemodialysis patients and in volunteers. It was seen that the concentration of the components of blood varies considerably. This variability is related to transport phenomena within as well as to the flow of masses across the cardiovascular compartment. From the continuous measurement of concentrations during hemodialysis treatment, relative changes in blood volume can be recorded in order to control the fluid balance of the patient. Rapid fluctuations at the macroscopic scale with periods of 5 to 30 seconds are due to heterogeneities at the microscopic scale and to the particular rheological behavior of the red blood cells at the level of the capillaries and the small blood vessels. The amplitude of rapid oscillations increased up to 1.2 % in terms of hematocrit values when there was rhythmic, spontaneous breathing at various frequencies. The measurement of concentrations at an accessible measuring site may be used to investigate the rheology of blood in the human microvasculature.
Keywords: density, sound speed, protein concentration, blood volume, oscillations
