In vitro comparison of output fluid temperatures for room temperature and prewarmed fluids

Objective To determine if prewarmed intravenous fluids produce superior fluid output temperatures compared with room temperature fluids at common anaesthetic fluid rates for small animal patients . Methods A prospective, randomised, in vitro fluid line test‐vein study was performed. Nine flow rates were analysed (10, 20, 60, 100, 140, 180, 220, 260 and 300 mL /hour) for room temperature fluids (21°C) and for five prewarmed fluids (40, 45, 50, 55 and 60°C) . Results For each flow rate tested, room temperature fluids never exceeded 25°C at any time point for each trial (range 18 to 25°C). For each flow rate tested, prewarmed fluids never exceeded 25 · 5°C at any time point for each trial (range 18 to 25 · 5°C). The mean output fluid temperature of prewarmed fluids was significantly warmer than room temperature fluids only at 300 mL /hour for 40°C (P = 0 · 0012), 45°C (P = 0 · 004), 50°C (P = 0 · 0002), 55°C (P = 0 · 0001) and 60°C (P < 0 · 0001) . Clinical Significance There was no thermodynamic benefit to utilising prewarmed intravenous fluids (up to 60°C) compared with room temperature intravenous fluids at common anaesthetic fluid rates for small animals .