Purpose: A newly developed fluid warmer (ThermoSens®) has a direct blood warming plate, which can result in hemolysis or red blood cell injury during heating. Therefore, to evaluate the safety of heating blood products with a fluid warmer, we conducted laboratory tests to study hemolysis and erythrocyte rheology.
Methods: We used outdated human blood taken from a Korean blood bank. Packed red blood cells mixed with 100 mL isotonic saline was passed through the fluid warmer. Blood flow was achieved by either gravity or 300 mmHg pressure. Blood samples were analyzed before and after heating for hemolysis marker and erythrocyte rheology parameters.
Results: The temperatures at the outlet were higher than 38°C at gravity and 300 mmHg pressure, respectively. There were no significant differences in hemolysis markers (hemoglobin, hematocrit, lactate dehydrogenase, and plasma free hemoglobin) or erythrocyte rheology (deformability, disaggregating shear stress, and aggregation index) between before and after heating (p > 0.05) except LDH at gravity (p = 0.0001).
Conclusion: The ThermoSens® fluid warmer caused no erythrocyte injury or negative effects on rheology during heating. Regarding medical device development, hemorheologic analysis can be useful for safety evaluation of medical devices that directly contact blood for temperature modulation.
Keywords: Fluid warmer; heating; hemolysis; hemorheology; hypothermia; transfusion.