Biorheology - Volume 27, issue 6

Authors: Schneditz, D. | Moser, M. | Smolle-Jüttner, F.M. | Dörp, E. | Pogglitsch, H. | Kenner, T.

Article Type: Research Article

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 behaviour 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. Show more

Keywords: density, sound speed, protein concentration, blood volume, oscillations

DOI: 10.3233/BIR-1990-27610

Citation: Biorheology, vol. 27, no. 6, pp. 895-902, 1990

Authors: Brückner, Uwe B. | Messmer, K.

Article Type: Research Article

Abstract: The interrelationship between systemic oxygen transport and hematocrit, has been studied under various conditions, while the influence of plasma viscosity on oxygen transport and tissue oxygenation has not entirely been explored. In experiments in dogs the plasma viscosity was increased either by isovolemic hemodilution with 6% hydroxyethyl starch (HES) 200/0.62, or 6% dextran-70, or by infusion of dextran-500 in a volume equivalent to 4% of blood volume from baseline to 3 mPa·s. Cardiac output and regional blood flow were assessed by means of radioactive labelled microspheres and local tissue oxygenation by means of pO2 multiwire surface electrodes. …In normotensive heal thy animals elevated plasma viscosity did neither jeopardize systemic nor regional blood flow; local tissue oxygenation of skeletal muscle remained unchanged or was even improved. We conclude that among the rheological factors influencing oxygen transport, the hematocrit plays the predominant role, while plasma viscosity is of minor importance. Show more

Keywords: plasma viscosity, hemodilution, organ blood flow, oxygen transport, dextran-70, dextran-500, hydroxyethyl starch 200/0.62, surface pO2

DOI: 10.3233/BIR-1990-27611

Citation: Biorheology, vol. 27, no. 6, pp. 903-912, 1990

Authors: Wolf, H.R.D. | Witte, S.

Article Type: Research Article

Abstract: Continuously measured oxygen uptake during constant work exercise (15′ 50W) reveals increasing oxygen consumption in individuals with elevated blood viscosity parameters, indicating persistent contribution of anaerobic glycolysis during steady state exercise far below expected “anaerobic threshold”. Improvement of viscosity parameters by prostaglandin E1 infusion (Prostavasin® ) 40 μ g i.v., naftidrofurylhydrogenoxalat (Dusodril® pi) 400 mg i.v. or hemodilution with 500 ml 6% hydroxyethylamylum MW 40000(Onkohaes® ) in 5 patients results in significant reduction of this oxygen gradient in subsequent exercise test. Integrated VO2 during exercise above the mean value at rest or the quotient of VO2 …during 15 min by VO2 during 30 min (including recovery time) are not differing significantly due to high variations inter- and intraindividually. Oxygen gradient during submaximal constant exercise permits direct clinical determination of microcirculatory performance in involved muscle tissue as a function of blood viscosity. Show more

Keywords: Blood viscosity, oxygen uptake, ergometry, microcirculation, muscle perfusion

DOI: 10.3233/BIR-1990-27612

Citation: Biorheology, vol. 27, no. 6, pp. 913-919, 1990

Authors: Hartert, H.

Article Type: Research Article

Abstract: Orbitometry (Hartert) is a rheological ex-vivo method to follow up physical assembly of a coagulum in layers during natural intensity of flow by orbital movement. Fibrin elasticity in the Orbitometers mode of Resonance Thrombography is differentiated from platelet activity as well as e.g. from the effects of disseminated coagulation - minimal in liver disease and maximal during disturbances of delivery. Transition into the mode of dynamic Tendography (Hartert) will e.g. register all fast going tests lasting minutes or seconds. It is comparable to an accelerated form of Thrombelastography (Hartert), the intercourse of which with coagulum yet is an exclusively static …operation. Another category is measurement of blood and plasma viscosity. In concentrated blood it seizes plasticity of blood cells as well as their intensity of aggregation in orbital flow. The latest methodical development of Orbitometry is control of platelet activity in its function of adhesion. This is realized by measurement of specific physical effects released in platelet containing coagulum. They generate a structural degradation of fibrin elasticity modul as well as a tendency for coagulum adhesion. The practical use of Adhesiography is control of anticoagulants and platelet protecting substances in their quantitative influence on coagulum structure and on the mentioned platelet activities. A special disturbance of these platelet depending mechanisms obviously is getting evidence in case of v.Willebrand’ s syndrome. Show more

Keywords: Orbitometer, fibrin elasticity, strain of flow, resonance, adhesiography, platelet shape change

DOI: 10.3233/BIR-1990-27613

Citation: Biorheology, vol. 27, no. 6, pp. 921-929, 1990

Article Type: Abstract

DOI: 10.3233/BIR-1990-27614

Citation: Biorheology, vol. 27, no. 6, pp. 931-961, 1990

Authors: Singh, Megha | Lucas, C.L. | Henry, G.W. | Ferreiro, J.I. | Wilcox, B.R.

Article Type: Short Communication

Keywords: Multiangle, Bifurcation, Steady flow, Reattachment point

DOI: 10.3233/BIR-1990-27615

Citation: Biorheology, vol. 27, no. 6, pp. 963-970, 1990

Authors: Pralhad, R.N.

Article Type: Letter

Abstract: Some errors have been observed in the analytical expression for the resistance to flow (λ R ), and in the computation of shear stress distribution (τ R ) in the analysis of Prawal Sinha and Chandan Singh (1). These errors have been rectified in the present analysis. Also, better values have been suggested for the couple stress parameter α ¯ for getting better results for λ R and τ R .

Keywords: Blood flow, Stenosis, Couple stress fluid, Hemodynamics

DOI: 10.3233/BIR-1990-27616

Citation: Biorheology, vol. 27, no. 6, pp. 971-974, 1990

Article Type: Other

DOI: 10.3233/BIR-1990-27617

Citation: Biorheology, vol. 27, no. 6, pp. 975-975, 1990