Axial drift of cells and partial plasma skimming in blood flowing through glass slits

¹ Kanematsu Memorial Institute, Sydney Hospital, Sydney, New South Wales, Australia

The distribution of red cells in citrated, heparinized, human blood flowing through slitlike glass channels of minor axis 30–35 µ was investigated by measuring the hematocrits from three closely set branches. With equal flow rates from the first and third branches carrying blood from each peripheral zone, the hematocrit difference, K, between axial and peripheral samples remained constant as the flow from the second branch, carrying the axial blood, was varied from 14 to 77% of the total flow. This indicates a progressive increase in hematocrit from near the wall to the axial plane such that laminar hematocrit is a linear function of the fraction of flow between the wall and the plane considered, whence simple expressions have been derived for partial plasma skimming at a dichotomous branch, and provided the velocity profile is parabolic across the short axis, for mean hematocrit and for mean red cell velocity within the channel. K was 16%, with inflowing blood hematocrit, H_M, 38.5%. As H_M increased from 0.1 to 70%, K/H_M fell roughly logarithmically.

Key Words: cell separation measurement in vitro • axial stream • hematocrit profile • capillary hematocrit • blood rheology • mean capillary red cell velocity

Submitted on May 24, 1965