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Erythrocyte deformability studied by viscometry and filtrometry
Department of Medicine, University Hospital, Lund, Sweden.
1995 (English)In: 3 Österreichische MTA-Tagung, Innsbruck, 1995: Verband det Diplomierten Medizin-Technischen Analytikerinnen Österreichs, Universitätsklinik, Innsbruck, maj 19-20 1995, 1995Conference paper, Published paper (Other academic)
Abstract [en]

Abstract

 This thesis deals with factors of major importance in filtrometric studies of human erythrocytes. After an introduction in the history and background of Clinical Hemorheology in general, the importance of erytrocyte deformability as one of the determinants of flow in the microcirculation is highlighted. In a short literature review the results obtained with some methods used for measurement of erythrocyte deformability i.e. viscometry, filtrometry and micropipette techniques, are compared. The practical part of this thesis concerns work performed with theSt. George'sFiltrometer and is presented in 5 separate papers (see below). The sensitivity and reproducibility of the method are assessed. Furthermore, the influence of anticoagulants and buffer media (inclusive human plasma), the importance of filtration pressure, the possible effect of damaged and hemolysed red cells (ghosts), the influence of variations in MCV and experimentally induced changes in cell membrane function are investigated. In a special chapter a survey is given of the factors that determine erythrocyte deformability. Besides the well known intrinsic factors (red cell shape and size, internal viscosity, elasticity of the cell membrane), extrinsic factors as there are shear stress, vessel geometry, temperature, osmolarity, proteins, drugs, blood gasses, pH and electrolytes are discussed. Finally a study with frozen and thawed erythrocytes is reported.

The following conclusions are drawn:

1. Red cell morphology, flow behaviour and also reproducibility of measurements are strongly dependent on the composition of the surrounding buffer medium. Eight different buffers have been tested and of these 8 buffers. PBS buffer (phosphate buffered saline) with a small amount (i.e. 2.5 gll) of albumin added, seems to give the most reliable measuring conditions.

2. The filtration pressure is an important factor in these studies. For theSt. George's Filtrometer the optimal pressure rang seems to be -30 to-50 mm H20.

3. Differences in MCV, even within the normal range, affected passage time, flow

resistance and number of clogging particles to a considerable degree, irrespective of pressure chosen. Similar differences in MCHC seems to affect these parameters less consistently.

4. Incubation of blood with ouabain caused a decrease in blood viscosity (p< 0.05)

compared to controls, although there was no change in red cell filterability parameters. In contrast, filterability measurements of erythrocytes, isolated from blood incubation with calcium, indicated significantly more rigid cells, but there was no increase in blood viscosity, measured at shear rates ranging from 0.8 to 40.0 s-1.

5. Addition of hydrocortisone to blood. in vitro. resulted an a decreased whole blood viscosity (pc0.005). However, also a deterioriated erythrocyte filterability (p< 0.005) was found. An increased plasma level of triglyzerides and total cholesterol was noted.

6. The St. George's Filtrometer seems to have a high capacity to detect and quantify preservation injuries in frozen, thawed and deglycerolized red cells.

Place, publisher, year, edition, pages
1995.
Identifiers
URN: urn:nbn:se:lnu:diva-11776OAI: oai:DiVA.org:lnu-11776DiVA, id: diva2:418042
Available from: 2011-05-19 Created: 2011-05-19 Last updated: 2011-09-16Bibliographically approved

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