Background Perioperative hypothermia is a common occurrence, particularly with the elderly and pediatric age groups. Hypothermia is associated with an increased risk of perioperative complications. One method of preventing hypothermia is warming the infused fluids given during surgery. The enFlow™ intravenous fluid warmer has recently been reintroduced with a parylene coating on its heating blocks. In this paper, we evaluated the impact of the parylene coating on the new enFlow’s fluid warming capacity. Methods Six coated and six uncoated enFlow cartridges were used. A solution of 10% propylene glycol and 90% distilled H2O was infused into each heating cartridge at flow rates of 2, 10, 50, 150, and 200 ml/min. The infused fluid temperature was set at 4 °C, 20 °C, and 37 °C. Output temperature was recorded at each level. Data for analysis was derived from 18 runs at each flow rate (six cartridges at three temperatures). Results The parylene coated fluid warming cartridge delivered very stable output of 40 °C temperatures at flow rates of 2, 10, and 50 ml/min regardless of the temperature of the infusate. At higher flow rates, the cartridges were not able to achieve the target temperature with the colder fluid. Both cartridges performed with similar efficacy across all flow rates at all temperatures. Conclusions At low flow rates, the parylene coated enFlow cartridges was comparable to the original uncoated cartridges. At higher flow rates, the coated and uncoated cartridges were not able to achieve the target temperature. The parylene coating on the aluminum heating blocks of the new enFlow intravenous fluid warmer does not negatively affect its performance compared to the uncoated model.

Current guidelines recommend the use of an intravenous fluid warmer to prevent perioperative hypothermia. Among the various methods of warming intravenous fluids, contact warmers are among the most effective and accurate, particularly in clinical conditions requiring rapid infusions of refrigerated blood or fluids. Contact warmers put the infusate in direct contact with a heating block. Some fluid warmers use heating blocks manufactured from aluminium. Several recent publications, however, have shown that uncoated aluminium blocks can leach potentially toxic amounts of aluminium into the body. In this review we performed a systematic literature review on aluminium leaching with contact fluid warmers and describe what manufacturer and competent authorities did in the past years to ensure patient safety. The search resulted in five articles describing the aluminium leaching. Four different devices (Level 1 Fluid Warmer from Smiths Medical, ThermaCor from Smisson-Cartledge Biomedical, Recirculator 8.0 from Eight Medical International BV, enFlow from Vyaire) were shown to leach high levels of aluminium when heating certain intravenous fluids. One manufacturer (Vyaire) voluntarily removed their product from the market, while three manufacturers (Eight Medical International BV, Smisson-Cartledge Biomedical, and Smiths Medical) revised the instructions for use for the affected devices. The enFlow fluid warmer was subsequently redesigned with a parylene coating over the heating block. The scientific literature shows that by using a thin parylene layer on the heating block, the leaching of aluminium can be nearly eliminated without affecting the heating performance of the device.