High-speed microcinematographic studies of blood flow in vitro.

The macroscopically steady flow of human blood at varying hematocrit values and flow rates through small glass capillaries has been studied by following in detail the motion of individual erythrocytes. At the microscopic level the flow was found to be nonuniform and unsteady. The shape of the average velocity profile of the erythrocytes was found to be in general more blunt than the Newtonian profile, and to be affected by concentration and flow rate, particularly in the capillaries of smaller diameter.