Augmentation of the cooling capacity of refrigerated fluid by minimizing heat gain of the fluid using a simple method of cold insulation.

OBJECTIVES: This study was undertaken to determine how rapidly refrigerated fluids gain heat during bolus infusion and to determine whether the refrigerated fluids could be kept cold by a simple cold-insulation method.

METHODS: One liter of refrigerated fluid was run through either a 16-gauge catheter (16G(-) and 16G(+) groups) or an 18-gauge catheter (18G(-) and 18G(+) groups) while monitoring the temperature in the fluid bag and the outflow site. In the 16G(+) and the 18G(+) groups, the fluid bag was placed with an ice pack inside an insulating sleeve during the fluid run.

RESULTS: In the 16G(-) and the 18G(-) groups, the outflow temperature increased to 10-12 degrees C during the fluid run. Meanwhile, outflow temperatures in the 16G(+) and the 18G(+) groups remained below 4.6 and 6.8 degrees C, respectively. The temperatures differed significantly between the 16G(-) and the 16G(+) groups (p < 0.001) and between the 18G(-) and the 18G(+) groups (p < 0.001), respectively.

CONCLUSIONS: Substantial heat gain occurred in the refrigerated fluid even during the relatively short duration of bolus infusion. The heat gain could, however, be easily minimized by cold insulation of the fluid bag.