[Hotline 2: heating capabilities of a coaxial fluid warming system at low and moderate flow rates].

Objective: The aim of this study was to compare the effects of two coaxial fluid warming systems with their heating capabilities.

Methods: The heating capabilities of two coaxial fluid warming systems and their capabilities to warm fluids at 20 +/- 0.5 degrees C (20 degrees C room temperature) was measured: 1) Hotline 1 Fluid Warmer, 2) Hotline(R) 1 Fluid Warmer. Final temperatures were measured at different infusion rates (10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 400, 800, 1000 ml/h and at maximal flow rates (Vmax)), at the distal end of the disposable tubing. Statistical analysis was performed using a computer based program (NCSS). Differences between the groups were analysed using the Two-Way-ANOVA. Significance was defined at a p < 0.05.

Results: At flow rates between 10 - 1000 ml/h, infusion temperatures of > 36 degrees C were attained by both devices in a reliable manner. Compared to Hotline 1, Hotline 2 attained higher final temperatures of between 1.2 - 3.8 % (p < 0.01). Hotline 1 was measured to have higher Vmax (+ 3.6 %) compared to Hotline 2 (p < 0.01). However, the mean final temperature at Vmax of Hotline 2 was increased by 6.5 % (p < 0.01). The time needed to warm target temperature to 40 - 41 degrees C took between 9 to 12 minutes (flow rate 10 ml/h and Vmax respectively) when using Hotline 1 and 3 to 4 minutes when using Hotline 2.

Conclusion: Compared to its predecessor, the Hotline 2 performance is a valuable improvement with respect to heating capacity and clinical handling.