An investigation of blood damage induced by static pressure during shear-rate conditions.

Many investigators have studied the effect of a mechanical force (shear rate, pressure, or temperature) on hemolysis. However, there exists no investigation of a relationship between the interactions of mechanical forces and hemolysis. The purpose of this study is to investigate the interactions of mechanical forces on hemolysis. We performed in vitro tests by using bovine blood, applying shear rate (0, 500, 1,000, and 1,500 s-1), positive pressure (0, 200, 400, and 600 mm Hg), and temperature (21, 28, and 35 degrees C) simultaneously. In all temperatures at the shear rate of 1,500 s-1, there are statistically significant differences in the hemolysis rate between 0 and 600 mm Hg (p < 0.05). However, to investigate the effect of temperature on hemolysis, shear stress was calculated at each blood temperature. There were no statistically significant differences among them. The results suggested that erythrocyte trauma caused by pressure related to the level of shear rate. It was found that the causes of hemolysis included the shear rate as well as shear rate and pressure.