Aluminium leaching in fluid warming devices – A Review

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.

Perioperative temperature management: a survey of 6 Asia–Pacific countries

Background Anesthesia leads to impairments in central and peripheral thermoregulatory responses. Inadvertent perioperative hypothermia is hence a common perioperative complication, and is associated with coagulopathy, increased surgical site infection, delayed drug metabolism, prolonged recovery, and shivering. However, surveys across the world have shown poor compliance to perioperative temperature management guidelines. Therefore, we evaluated the prevalent practices and attitudes to perioperative temperature management in the Asia–Pacific region, and determined the individual and institutional factors that lead to noncompliance. Methods A 40-question anonymous online questionnaire was distributed to anesthesiologists and anesthesia trainees in six countries in the Asia–Pacific (Singapore, Malaysia, Philippines, Thailand, India and South Korea). Participants were polled about their current practices in patient warming and temperature measurement across the preoperative, intraoperative and postoperative periods. Questions were also asked regarding various individual and environmental barriers to compliance. Results In total, 1154 valid survey responses were obtained and analyzed. 279 (24.2%) of respondents prewarm, 508 (44.0%) perform intraoperative active warming, and 486 (42.1%) perform postoperative active warming in the majority of patients. Additionally, 531 (46.0%) measure temperature preoperatively, 767 (67.5%) measure temperature intraoperatively during general anesthesia, and 953 (82.6%) measure temperature postoperatively in the majority of patients. The availability of active warming devices in the operating room (p < 0.001, OR 10.040), absence of financial restriction (p < 0.001, OR 2.817), presence of hospital training courses (p = 0.011, OR 1.428), and presence of a hospital SOP (p < 0.001, OR 1.926) were significantly associated with compliance to intraoperative active warming. Conclusions Compliance to international perioperative temperature management guidelines in Asia–Pacific remains poor, especially in small hospitals. Barriers to compliance were limited temperature management equipment, lack of locally-relevant standard operating procedures and training. This may inform international guideline committees on the needs of developing countries, or spur local anesthesiology societies to publish their own national guidelines.

Aluminium release and fluid warming: provocational setting and devices at risk

Background Fluid warming, recommended for fluid rates of > 500 ml h-1, is an integral part of patient temperature management strategies. Fluid warming devices using an uncoated aluminium containing heating element have been reported to liberate aluminium resulting in critical aluminium concentrations in heated fluids. We investigated saline solution (0.9%), artificially spiked with organic acids to determine the influence of fluid composition on aluminium release using the uncoated enFlow® device. Additionally, the Level1® as a high volume fluid warming device and the ThermoSens® device were investigated with artificial spiked fluid at high risk for aluminum release and a clinically used crystalloid solution. Results Saline solution spiked with lactate more than acetate, especially at a non neutral pH, led to high aluminium release. Next to the enFlow® device, aluminium release was observed for the Level1® device, but not for the coated ThermoSens®-device. Conclusion Uncoated aluminium containing fluid warming devices lead to potentially toxic levels of aluminium in heated fluids, especially in fluids with non-neutral pH containing organic acids and their salts like balanced electrolyte solutions.

Importance of Postoperative Use of External Warming Devices in Flap Reconstructive Surgery

Flap failure, partial or complete, can have great negative impact on the patient and the reconstructive outcome. The effect of thermal regulation on flap survival is well recognized. This article focuses on the importance of external warming devices as a standard on postoperative flap care to avoid any temperature-related vascular compromise. PubMed, Medline, and EMBASE search had been performed. More than 60 papers have been reviewed. Out of them, that 29 references have been included in this review. The authors emphasize on the importance of strict postoperative flap temperature control with active warming devices as a standard of practice to minimize any related microcirculatory changes.

Aluminium Release and Fluid Warming: Provocational Setting and Devices at Risk

BACKGROUND: Fluid warming, recommended for fluid rates of > 500 ml h-1, is an integral part of patient temperature management strategies. Fluid warming devices using an uncoated aluminum containing heating element have been reported to liberate aluminum resulting in critical aluminum concentrations in heated fluids. We investigated saline solution (0.9%), artificially spiked with organic acids to determine the influence of fluid composition on aluminum liberation using the uncoated enFlow® device. Additionally the Level1® as a high volume fluid warming device and the ThermoSens® device were investigated. RESULTS: Saline solution spiked with lactate more than acetate, especially at a non acid pH, led to high aluminum liberation. Next to the enFlow® device, aluminum liberation was observed for the Level1® device, but not for the coated TermoSens®-device. CONCLUSION: Uncoated aluminum containing fluid warming devices lead to potential toxic levels of aluminum in heated fluids, especially in non acid fluids containing organic acids and their salts.

Effects of a Heated Anesthesia Breathing Circuit on Body Temperature in Anesthetized Rhesus Macaques (Macaca mulatta)

This study evaluated the effects of using a heated anesthesia breathing circuit in addition to forced-air warming on bodytemperature in anesthetized rhesus macaques as compared with forced-air warming alone. Hypothermia is a common perianestheticand intraoperative complication that can increase the risk of negative outcomes. Body heat is lost through 4 mechanisms during anesthesia: radiation, conduction, convection, and evaporation. Typical warming methods such as forced-air warming devices, conductive heating pads, and heated surgical tables only influence radiative and conductive mechanisms of heatloss. A commercially available heated breathing circuit that delivers gas warmed to 104 °F can easily be integrated into ananesthesia machine. We hypothesized that heating the inspired anesthetic gas to address the evaporative mechanism of heatloss would result in higher body temperature during anesthesia in rhesus macaques. Body temperatures were measured at 5-min intervals in a group of 10 adult male rhesus macaques during 2 anesthetic events: one with a heated anesthesia breathing circuit in addition to forced-air warming, and one with forced-air warming alone. The addition of a heated breathing circuit had a significant positive effect on perianesthetic body temperature, with a faster return to baseline temperature, earlier nadir of initial drop in body temperature, and higher body temperatures during a 2-h anesthetic procedure. Use of a heated anesthesia breathing circuit should be considered as a significant refinement to thermal support during macaque anesthesia, especially for procedures lasting longer than one hour.

Comparison of two forced-air warming devices during foot and ankle surgery: a randomised controlled trial

Inadvertent perioperative hypothermia is a frequent problem associated with surgical patients which can have significant consequences during surgery and in the immediate postoperative period. We compared 35 randomised patients using over vs. under body forced air heating. There were no statistically significant differences between some demographic and surgical parameters such as: age, weight, height, body mass index, length of anaesthesia and operation. Statistically significant differences were found between the patient’s admission to the operating room and 30 minutes and the end of the procedure on the under body patients group. This study analyses a uniform population of patients (Foot and Ankle Surgery) previously not studied and supports the use of under body blankets.

A Novel Approach to Maintaining Normothermia in Major Spinal Deformity Surgery with an Esophageal Warming Device

Maintenance of normothermia is a priority during major spinal deformity surgery. However, this is difficult due to the large body surface area exposed to ambient temperatures. We report the novel use of an esophageal warming device, added to standard care, to maintain normothermia in three patients. We conclude that esophageal warming is feasible in major spine surgery with no apparent complications. Safety and efficacy, as compared to standard warming devices, will need to be determined in future prospective trials.