[Heating capabilities of fluid warming systems during low infusion rates]

The aim of the study was to compare the effects of different fluid warming systems on their heating capabilities during low infusion rates.

Heating capabilities of four different fluid warming systems and their capabilities to warm fluids with 20 +/- 0.5 degrees C above 32 degrees C were measured: 1) Hotline(R) Fluid Warmer, 2) Gymar, using three disposable tubing systems - "Pediatric", "Standard", and "High-Flow", 3) Astotherm, and 4) Astotherm plus 260. Low to moderate infusion rates (100, 300, 600, and 900 ml/h) were achieved using motor pumps. Infusate temperatures were measured at 17 degrees C and 20 degrees C room temperature at the distal end of the disposable tubing. Statistical analysis was performed using a computer based program (NCSS). Differences between the groups were analysed by the unpaired Wilcoxon Test. Significance was defined with a p < 0.05.

During low to moderate infusion rates (100 - 900 ml/h), infusate temperatures of > 32 degrees C were attained only by the Hotline-device in a reliable manner independent of the applied room temperature. The devices Astotherm plus 260 und Astotherm attained these temperatures during infusion rates of 300 ml/h and 600 ml/h respectively. Final temperatures of > 32 degrees C were maintained by Gymar during infusion rates of 600 ml/h, when the disposable tubing system "Pediatric" was used. Using the same device but different tubing systems, final temperatures of >32 degrees C were attained during 900 ml/h ("Standard") or failed ("High-Flow"). With all devices, increasing the room temperature by 3 degrees C was followed by higher infusate temperatures, which were more pronounced in those devices without disposable tubing warming (p < 0.01).

In this laboratory investigation, Hotline performance was superior with respect to providing final temperatures > 32 degrees C during low to moderate infusion rates. Astotherm Plus 260 seems to be an alternative cost effective device in case of infusion rates of more than 300 ml/h.