Performance Characteristics of Ultratherm??? Fluid Warmer

Ultratherm Infusion Fluid Warmer Model 3703-1 (Ultratherm) is a disposable device approved by the Food and Drug Administration to warm fluids including blood and nutritional fluids. It has no temperature monitor or audible alarm and uses air-activated chemical heating elements in direct contact with loops of intravenous (i.v.) tubing. We studied the warming of blood and saline by Ultratherm using intratubing thermocouple wire probes. Internal warmer chamber temperature reached 58 degrees C within 40 min of activation, and a plateau of approximately 65 degrees C reached in 1 h was sustained over the next 5 h. Free hemoglobin measurements on 47 degrees C and 53 degrees C blood samples obtained as blood exited the warmer at 30 mL/h demonstrated 0.6% and 7% hemolysis, respectively. Room temperature blood at 500 mL/h and refrigerated blood at 100 mL/h were warmed to approximately 36 degrees C. Refrigerated blood at 500 mL/h was not warmed above 19 degrees C. At flow rates of 500, 100, and 30 mL/h, room temperature saline reached 34 degrees C, 45 degrees C, and 52 degrees C, respectively. The unmonitored, high, internal warmer chamber temperatures preclude the use of Ultratherm with blood or any fluids potentially damaged by excessive heat, and its use should be limited strictly to clear fluids. The utility of the warmer, even with clear fluids, is further limited to room temperature fluids, to a time interval between 1 and 6 h following activation, and to flow rates between 100 and 500 mL/h.(ABSTRACT TRUNCATED AT 250 WORDS)