Effect of varying external pneumatic pressure on hemolysis and red blood cell elongation index in fresh and aged blood: Randomized laboratory research.

Background: External applied pneumatic pressure is usually used for rapid transfusion of red blood cells (RBCs). However, increased shear stress can cause increased hemolysis and decreased RBC elongation indices. Therefore, the purpose of this study was to measure the degree of hemolysis and the alteration of RBC elongation indices under varying external pressure in fresh and aged blood.

Methods: Venous blood samples were obtained from 20 healthy human volunteers. Each blood bag was divided into 2 subgroups (5 or 35 days of storage), and 5 levels of pressure were applied: 0, 150, 200, 250, and 300 mmHg. After infusion, a laboratory study was conducted. The percentages of irreversibly changed cells were evaluated using Bessis classification. RBC elongation indices were measured using a microfluidic ektacytometer.

Results: There were no significant differences in the percentage of irreversibly changed RBCs between the pressures of 0 and 300 mmHg. Moreover, there were no significant differences in laboratory test results or elongation indices among all levels of pressure. Irreversibly changed RBCs and hemolysis were increased depending on the storage period.

Conclusion: Irreversible changes in RBCs did not occur as a result of external pressure. The hemolysis and elongation indices of fresh RBCs were not influenced by external pneumatic pressure up to 300 mmHg. Only the storage period affected the irreversible changes in RBCs and hemolysis. Therefore, the application of external pressure to RBCs in variously aged blood is likely to be a safe procedure.