Evaluation of the Performance and Safety of a Newly Developed Intravenous Fluid Warmer

To evaluate the performance and safety of a newly developed blood warmer (ThermoSens), we tested its heating capability under various conditions using isotonic saline and hemolysis analysis with swine blood. The following two in vitro tests were performed: (i) To investigate the performance of the device, the inflow and outflow temperatures were measured at various flow rates (30, 50, and 100 mL/min) using cold (5°C) and room temperature (20°C) isotonic saline (0.9%). Several parameters were measured including the highest temperature of the outlet, the time required to reach the highest temperature, and the temperature of the intravenous line. (ii) To investigate the safety of the device, a hemolysis test was performed using swine blood. We obtained 320 mL of whole blood from swine and refrigerated the blood for 35 days at 3°C. In order to replicate the clinical situation, blood flow by gravity and pressure (300 mm Hg) was used. Before and after the heating test, blood samples were obtained and a comparison was made between these samples. Hemoglobin, hematocrit, lactate dehydrogenase, and plasma hemoglobin were used for red blood cell (RBC) damage analysis. The highest outlet temperatures obtained using flow rates of 30, 50, and 100 mL/min were 39.10 ± 0.59, 39.25 ± 0.69, and 37.63 ± 1.03°C, respectively, with cold saline, and 39.40 ± 0.40, 39.66 ± 0.36, and 39.49 ± 0.49°C, respectively, with room temperature saline. Hemolysis tests showed no significant changes in hemoglobin, hematocrit, lactate dehydrogenase, or plasma hemoglobin (P > 0.05) between before and after heating for both gravity and pressure blood flow. The ThermoSens blood warmer warms isotonic saline effectively, reaching temperatures up to 36°C under various conditions. Hemolysis tests showed no RBC damage. Therefore, the newly developed ThermoSens has good heating performance and is safe for RBC products.