Few studies have investigated the effectiveness of intravenous fluid warmers at low and moderate flow rates below 1,000 ml/h. In this study, we compared the effectiveness of three different fluid warmers at a low flow rate (440 ml/h).

We experimentally investigated the fluid warming performances of Mega Acer Kit® (Group M, n = 10), Ranger™ (Group R, n = 10), and ThermoSens® (Group T, n = 10) at 440 ml/h for 60 min. All devices were set at a warming temperature of 41℃ with preheating for 10 min. Intravenous fluids were then delivered through them. The fluid temperature (primary endpoint) was measured at 76 cm from the device after infusion for 60 min. The expected decrease in mean body temperature (secondary endpoint) after 5 h infusion for a 70 kg patient (ΔMBT5) was also calculated.

The fluid temperature (mean [95% CI]) at 76 cm from the device, 60 minutes after the infusion was higher in group M (36.01 [35.73–36.29]℃), compared to groups T (29.81 [29.38–30.24]℃) and R (29.12 [28.52–29.72]℃) (P < 0.001). The ΔMBT5 (mean [95% CI]) was significantly smaller in group M (−0.04 [−0.04 to −0.03]℃) than that in groups T (−0.27 [−0.28 to −0.29]℃; P < 0.001) and R (−0.30 [−0.32 to −0.27]℃; P < 0.001). However, none of the fluid warmers provided a constant normothermic temperature above 36.5℃.

Mega Acer Kit® was more effective in warming the intravenous fluid with the smallest expected change in the mean body temperature, compared to Ranger™ and ThermoSens®, at a flow rate of 440 ml/h.