This protocol is really significant for demonstrating a powerful approach to esophageal cooling or warming during left atrial ablation for the treatment of atrial fibrillation. The advantage of this system compared to standard thermal monitoring is that this system allows for thermal energy transfer rather than waiting for temperature changes to occur. This technique also voids the need for procedure delay and device manipulation as with other methods used to reduce a esophageal injury.
This technique is easy to implement and can be used for both radio frequency ablation and cryoablation. Demonstrating the procedure will be Natalie Zoltek, RN, MSN. Begin by attaching the esophageal temperature management device to the heat exchanger via the device connectors.
Power on the unit, place it in manual mode, and ensure that the water is flowing through the device with no leaks. Determine the appropriate insertion depth by measuring from the patient's lips to the earlobe and from the earlobe to the xiphoid process, noting this depth on the device. Next, use a water soluble lubricant to generously lubricate between 15 and 25 centimeters of the distal end of the device.
If possible, extend the patient's head to further facilitate insertion, and apply gentle pressure posteriorly downwards to insert the device past the oral pharynx and into the esophagus. To increase ease of placement, consider pinching the water outflow tract to increase device stiffness. If the endotracheal tube cuff is over inflated, consider temporary pressure reduction via air removal to avoid compressing the esophageal pathway.
Determine the placement location via fluoroscopy to check if the tip of the device is below the diaphragm. Secure the water hoses and device to avoid accidental dislodgement. And, if stomach decompression is desired, connect the central lumen to allow intermittent suction.
The device can be visualized with intracardiac echocardiography or ICE. For a radio frequency or RF ablation, ensure that the heat exchanger is set to manual mode and that the appropriate water temperature is set. On the typical heat exchanger press the temp control button and use the up and down arrows to select the target water temperature.
Once the digital display shows the desired target temperature, initiate water flow by pressing the manual control button. Use a water temperature setpoint of 14 degrees Celsius for initial insertion. Approximately 15 to 20 minutes before application of RF energy, change the set point to four degrees Celsius.
For additional antiinflammatory effects of cooling after RF ablation, maintain the water temperature setpoint at four degrees Celsius for up to 20 minutes after the completion of posterior wall ablation For cryoablation set the water temperature to 42 degrees Celsius shortly after placement. And provide additional patient warming if needed to counter the systemic cooling effect of cryoablation. During ablation the patient temperature will usually stay in a normal thermic range.
To measure patient temperature, use any approved thermometer other than esophageal since device interference will prevent accuracy. If needed to maintain patient temperature while using the esophageal cooling, supplemental warming modality, such as warming blankets or head covers can be used. Confirm water flow at the correct temperature by checking the setpoint and touching the device, which should be firm to ensure adequate pressure and appropriate temperature.
When troubleshooting, ensure that there is no blockage of water flow. The water paddle wheel, if present, should be continuously spinning and the low flow alarm should not be activated. If blockage occurs, stop treatment and determine the cause and location of obstruction.
To remove the device, press the appropriate button to pause water flow, close clamps on the hose set and device tubing, if present, and withdraw the device by gently pulling anteriorly in a similar manner to standard oral gastric tube removal. Power down the heat exchange unit via the power switch, prior to unplugging from wall power. Disconnect the water hose connectors from the device and dispose according to institutional guidelines.
A meta-analysis of existing studies found that esophageal cooling via direct installation of cold liquid into the esophagus during RF ablation, results in a 61%reduction in high-grade lesion formation. Data from a randomized controlled clinical trial evaluating a dedicated cooling device, shows a statistically significant 83%reduction in endoscopically identified lesions compared to standard LET monitoring. Sample case studies of RF and cryoablation, in combination with an esophageal heat transfer device, are outlined in the text manuscript.
When attempting this procedure, it is important to ensure that water's flowing continuously prior to placement to provide sufficient stiffness and when the device is being used to ensure continuous heat transfer.
