Heating and Cooling Rates With an Esophageal Heat Exchange System

Abstract

BACKGROUND:The Esophageal Cooling Device circulates warm or cool water through an esophageal heat exchanger, but warming and cooling efficacy in patients remains unknown. We therefore determined heat exchange rates during warming and cooling.METHODS:Nineteen patients completed the trial. All had general endotracheal anesthesia for nonthoracic surgery. Intraoperative heat transfer was measured during cooling (exchanger fluid at 7°C) and warming (fluid at 42°C). Each was evaluated for 30 minutes, with the initial condition determined randomly, starting at least 40 minutes after induction of anesthesia. Heat transfer rate was estimated from fluid flow through the esophageal heat exchanger and inflow and outflow temperatures. Core temperature was estimated from a zero-heat-flux thermometer positioned on the forehead.RESULTS:Mean heat transfer rate during warming was 18 (95% confidence interval, 16–20) W, which increased core temperature at a rate of 0.5°C/h ± 0.6°C/h (mean ± standard deviation). During cooling, mean heat transfer rate was −53 (−59 to −48) W, which decreased core temperature at a rate of 0.9°C/h ± 0.9°C/h.CONCLUSIONS:Esophageal warming transferred 18 W which is considerably less than the 80 W reported with lower or upper body forced-air covers. However, esophageal warming can be used to supplement surface warming or provide warming in cases not amenable to surface warming. Esophageal cooling transferred more than twice as much heat as warming, consequent to the much larger difference between core and circulating fluid temperature with cooling (29°C) than warming (6°C). Esophageal cooling extracts less heat than endovascular catheters but can be used to supplement catheter-based cooling or possibly replace them in appropriate patients.

Modeling esophageal protection from radiofrequency ablation via a cooling device: an analysis of the effects of ablation power and heart wall dimensions

“…The device is available for a range of patient temperature management needs, and provides a high flow rate of water through a closed-circuit multi-channel 12-mm-diameter cylindrical silicone tube placed in the esophagus analogously to a standard orogastric tube (images and video available at https://www.attune-medical.com/ ). The device has a large heat transfer capacity and is currently used in cooling mode for the reduction of patient core body temperature from febrile or normothermic states, in warming mode for the prevention of inadvertent perioperative hypothermia, and in a feedback-control mode (automatically warming or cooling) for a variety of temperature management needs [ 17 – 20 ]. In order to further investigate the potential of this new approach, and quantify the possible efficacy, we sought to develop a mathematical model of this process and evaluate performance over a range of expected operating conditions while comparing output to recently available clinical data.…”

Short interruptions between pre‐warming and intraoperative warming are associated with low intraoperative hypothermia rates

“…Forced‐air warming was the only heat‐supply method in this study. Alternatives like conductive heat supply systems or combinations of convective and conductive warming devices which have also shown effectiveness were not analysed …”

“…Alternatives like conductive heat supply systems or combinations of convective and conductive warming devices which have also shown effectiveness were not analysed. [12][13][14] The concept of focusing on the dichotomous outcome value hypothermia (body core temperature <36.0°C) is recommended in the NICE and German and Austrian guidelines. 2,3 Alternatively, it could be discussed to use the combination of temporal duration and low core temperature (area under the curve for body core temperature <36°C).…”

Core warming of coronavirus disease 2019 (COVID-19) patients undergoing mechanical ventilation – a protocol for a randomized controlled pilot study

“…Core temperature control and warming will be performed with a commercially available esophageal heat exchange device (ensoETM, Attune Medical, Chicago, IL). This device is currently used world-wide for various patient temperature management goals, including postcardiac arrest therapeutic hypothermia, [44][45][46][47] warming of burn patients, [48] warming general surgical patients, [49] cooling traumatic brain injury, [50] cooling heat stroke, [51] and the treatment of central fever. [52,53] The device is a multi-chambered silicone tube placed in the esophagus and connected to a heat exchanger to provide heat transfer to or from a patient (video available at https://vimeo.com/306506411).…”