Amount of air infused to patient increases as fluid flow rates decrease when using the Hotline HL-90 fluid warmer

The intraoperative use of fluid warming devices has been recommended to avoid perioperative hypothermia and related adverse outcomes. To evaluate whether these devices might introduce risks of their own, we measured the volume of air escaping from a warmed intravenous solution that might be delivered to a patient.

In an operating room maintained at 19-19.5 degrees C, we tested an HL-90 Hotline fluid warmer with the L-70 fluid-warming set. One liter of lactated Ringer's solution was infused at flow rates of 150, 300, 500 and 3400 ml/h. The air that formed within the L-70 tubing during infusion was collected in a bubble trap placed at the end of the L-70 tubing. The volume of air in the bubble trap was measured. Twelve separate measurements were obtained at each flow rate. One additional study (n = 8) was performed using the L-10 Gas Vent to determine whether this equipment might reduce the volume of air infused when fluid flow rate was 300 mL/h. The volume of air collected at each flow rate was compared using ANOVA.

Volume of air increased significantly from 1.0 +/- 0.2 mL to 2.9 +/- 0.4 ml as flow rate decreased from 3400 ml/h to 150 ml/h (p < 0.0001). The L-10 gas eliminator was ineffective in reducing the amount of air infused.

We conclude that the use of the Hotline fluid warmer can result in infusion of air into the patient, introducing possible risk of air embolism.