17
Views
0
CrossRef citations to date
0
Altmetric
Original Article

Resistance to Blood Flow in Nonuniform Capillaries

&
Pages 421-427 | Received 23 Apr 1997, Accepted 17 Sep 1997, Published online: 10 Jul 2009
 

Abstract

Objective: Microvessels in living tissues are not uniform cylinders, and red blood cells (RBCs) are continually deformed when traversing them. This may contribute to higher resistance to blood flow observed in microvessels compared with that in corresponding uniform glass tubes. Here, a theoretical model was used to estimate flow resistance in nonuniform capillaries and its dependence on hematocrit, flow rate, and mechanical properties of RBCs.

Methods: Single-file motion of RBCs through capillaries with sinusoidally varying cross-sections was simulated, assuming axisymmetrical geometry. Effects of cell membrane shear viscosity and elasticity were included. Lubrication theory was used to describe the plasma flow.

Results: Predicted resistance to blood flow in capillaries with variable cross-sections was substantially higher than in uniform vessels with the same mean diameters. Resistance depended on vessel geometry, flow rate, and hematocrit. At tube hematocrit 30%, the increase in resistance was 40%–58% when diameter varied between 4.5 and 6 μm with wavelength 20 μm and 58%–77% for variations between 4 and 5 μm with wavelength 10 μm. Larger relative increases in resistance were predicted for RBCs with increased membrane shear viscosity.

Conclusions: Effects of transient RBC deformations in irregular capillaries contribute significantly to blood flow resistance in capillaries. However, this effect is not sufficient to account for the flow resistance observed in living tissues.

Reprints and Corporate Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

To request a reprint or corporate permissions for this article, please click on the relevant link below:

Academic Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

Obtain permissions instantly via Rightslink by clicking on the button below:

If you are unable to obtain permissions via Rightslink, please complete and submit this Permissions form. For more information, please visit our Permissions help page.