Rheologic measurements on small samples with a new capillary viscometer.
A newly developed capillary viscometer (capillary diameter 496 micron, length 10 cm) was tested and used for measurement of blood viscosity. The determination of pressure drop along the capillary during a constant flow allowed the calculation of the apparent viscosity. By changing the flow rate, the shear rate could be varied from 0.67 to 590 sec-1. A sample of 0.5 ml was sufficient for readings to be made at 10 shear rates in this range. Measurements of distilled water and standard oils were in good agreement with the expected values. Measurements on adult human plasma and umbilical cord blood were compared with simultaneous readings by Couette viscometer. For whole blood at various shear rates, regression analysis between the viscosity obtained from the capillary viscometer and that from the Couette viscometer yielded excellent correlation (r = 0.968, p less than 0.001). This capillary viscometer with high precision for very small samples is useful for various clinical applications.
D000328:Adult; D000368:Aged; D001794:Blood Pressure; D001809:Blood Viscosity; D005260:Female; D005312:Fetal Blood; D006330:Heart Defects, Congenital / Q000097:blood; D006400:Hematocrit; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008258:Waldenstrom Macroglobulinemia / Q000097:blood