Microwave warming of resuscitation fluids

Hypothermia is a common complication in fluid resuscitation of the hypovolemic patient. Warm intravenous (IV) fluids have been shown to be a valuable adjunct in volume replacement to prevent this complication. A rapid method of warming IV fluids is the microwave oven. Heating time for liter bags of crystalloid to 39 C was determined to be two minutes at high power, 600 W. Fresh frozen plasma was thawed with five 30-second exposures to microwave radiation. Microwave warming of packed red blood cells (PRBC), 4 C to 37 C, resulted in a 17-fold increase in plasma hemoglobin over that of water bath controls, (P greater than .01). Heating on a warm cycle to room temperature, 21 C, caused an average 26% increase in plasma hemoglobin. Therefore, we do not advocate microwave warming of PRBC because of the possible danger of local overheating, which causes hemolysis. We warm PRBC secondarily by diluting with microwave-warmed, calcium-free crystalloid.