An assessment of the thermal safety of microwave warming of crystalloid fluids

Abstract

We performed an in vitro study to determine the thermal safety of a domestic microwave to warm intravenous crystalloid solutions. Five-hundred-millilitre bags of crystalloid, randomly allocated to groups which differed in power setting, timer setting and whether or not agitation was performed after warming, were heated in a microwave oven to a calculated temperature of 39 degrees C. Timer accuracy was checked by stopwatch. Bag temperature was measured using an infrared tympanic temperature probe and fluid temperature was measured with an in-line thermocouple. Mean times measured by stopwatch were higher than set. No in-line temperatures reached 40 degrees C. Wider overall ranges and a higher mean were found with the tympanic probe compared with in-line temperature measurement. There were significant differences between the in-line temperatures of shaken and unshaken bags at each power setting, but not when groups were added together. There was no change in colour or odour of bags or fluid. One bag developed a pinhole leak when the packaging was removed.

A comparison of the warming capabilities of two Baragwanath rewarming appliances with the Hotline fluid warming device

“…These include storing the fluid in a fluid-warming cabinet, [1] prewarming the fluids in a warm-water bath [19] or heating the fluid in a microwave. [20] These methods have been shown to be superior at maintaining core temperature (compared with administering room-temperature fluid) and are also comparable with the performance of commercially available in-line fluid-warming devices such as the Hotline apparatus (ICU Medical Inc., USA). [1] Resource-limited settings challenge the delivery of acceptable levels of care and low-and middle-income countries are most affected.…”

“…Recommendations have been published on the optimal use of these creative solutions. Lindhoff and Palmer [20] described the optimal use of a microwave for prewarming IV fluids. [20] Shah et al [21] described a novel fluidwarming device using a non-sterile latex glove filled with warmed water to heat a coil of IV fluid being administered to the patient.…”

“…Lindhoff and Palmer [20] described the optimal use of a microwave for prewarming IV fluids. [20] Shah et al [21] described a novel fluidwarming device using a non-sterile latex glove filled with warmed water to heat a coil of IV fluid being administered to the patient. Craig et al [22] described a method of prewarming IV fluids using a warm air blower and a modified cooler box.…”