Red blood cell damage by shear stress.

A series of careful studies has been made on blood damage in a rotational viscometer. Specific attention has been focused on the effects of solid surface interaction, centrifugal force, air interface interaction, mixing of sheared and unsheared layers, cell-cell interaction, and viscous heating. The results show that there is a threshold shear stress, 1500 dynes/cm(2), above which extensive cell damage is directly due to shear stress, and the various secondary effects listed above are negligible. By analysis of these results and those of prior workers it is shown that the exposure time-shear stress plane is divided into two distinct regimes. In the regime of relatively low stresses and exposure times there is relatively little damage, and the damage is dominated by solid surface interaction effects. In the other regime, at high stresses and exposure times, stress effects alone dominate and very high rates of hemolysis occur. The experimental findings of all prior workers are shown to be consistent when interpreted in this way.