Delivery Temperature of Warmed Saline or Blood at Variable Flow Rates

ABSTRACT

PURPOSE: This study was undertaken to determine the effect of the infusion rate on the temperature of the infusate reaching the distal end of an infusion tubing with active fluid warming. METHODS: One-liter bags of normal saline were warmed to 6 0 degrees C using a microwave oven and were then run through standard infusion tubing at rates of 200, 400, 600, 800, and 1,000 mL/hr. The temperatures at the distal end of the infusion tubing were measured every one minute for the first 10 minutes and then every ten minutes for 1 hour. Subsequently, normal saline and packed red blood cells, which were warmed using a fluid warmer, were infused at rates of 200, 400, 600, 800, and 1,000 mL/hr. Temperatures were recorded when the readings had stabilized within a range of +/-0.1 degrees C. RESULTS: Normal saline warmed by a microwave oven could be delivered through standard infusion tubing at a temperature of more than 37 degrees C if the normal saline had been preheated to 60 degrees C and infused through long tubing (210 cm) at rates of 800 and 1,000 mL/hr. Also, normal saline and packed red blood cells, warmed to 41 degrees C with a fluid warmer, could be delivered at a temperature of or near 3 7 degrees C through relatively short tubing (110 cm) at a rate of 1,000 mL/hr. The fluid composition influenced the infusate temperature (p < 0.05). CONCLUSION: When patients with hypothermia or major trauma are treated by infusing warmed normal saline or packed red blood cells, we should consider appropriate flow rates for the fluid so as to maintain a therapeutic delivery temperature when using practical infusion tubing in the ED setting.