Intra-Operative Neural Monitoring of Thyroid Surgery in a Porcine Model

This method can help answer key questions about the application of intraoperative neural monitoring during clinical thyroid surgery, and the electrophysiological characteristics of normal and injured that occur in nerves. Some advantages of using the porcine models are that the anatomy and the physiologies are similar to humans. And that the size of the animals enable easy handling.

The implications of this technique is stand toward the establishment of reliable strategies for preventing and operating nerve injury. As various occur hydro nerve, injury types can be induced experimentally. Demonstrating procedure will be Pao-Chu Hun, the veterinarian from the laboratory animal center.

Hsiu-Ya Chen our nurse specialist, from the anesthesiology department. And Li-Ying Chaung, an assistant from the E&D department. Begin by placing a three to four month old piglet in the prone position on the operating table with the head and body aligned, to facilitate a clear visualization of the upper airway.

Have an assistant to apply traction of the upper and lower jaw to maintain an adequate mouth opening, and place the laryngoscope upside down directly into the oral cavity to depress the tongue. Use the laryngoscope to press the epiglottis downward toward the tongue base. Gently advancing the elastic bougie into the trachea when the vocal cords can be clearly visualized.

Advance the electromyography, or EMG tube at the corner of the mouth to a depth of 24 centimeters, and use medical tape to fix the tube at the mouth angle. Then connect the EMG tube to the ventilator. Connect the channel leads from the EMG tube to the monitoring system, and set the monitoring system to run a 50 millisecond time window.

Set the pulse to stimuli to 100 microseconds, and four hertz, and set the event capture threshold to 100 micro volts. Wearing sterile surgical gloves, use a scalpel to make a 10 to 15 centimeter transverse collar incision to expose the neck and the larynx. And erase the subplot of small flap one centimeter cranially from the clavicle to the hyoid bone.

Remove the strap muscles to visualize the tracheal rings and nerves, and use a handheld stimulation probe to carefully expose the external branch of the superior laryngeal nerve, the RLN, and the vagus nerve. Position an automated periodic stimulation electrode on one side of the vagus nerve for stimulation during continuous enter operative neural monitoring, and connect the electrode to the monitoring system. Then set the post stimuli to one hertz 100 microseconds, and one milliamp.

To assess the effects of muscle relaxants, and the reversals on nerve responses, apply continuous enter operative neural monitoring. Administer a bolus injection of 0.3 milligrams per kilogram rocuronium in a 10 mg per milliliter volume, and observe the real time EMG changes. Three minutes after injection, perform one injection of two milligrams per kilogram sugammedex in a 100 mg per milliliter volume, as a rapid bolus, and record the recovery profile of the laryngeal EMG.

To simulate direct nerve stimulation as occurs during surgery, apply one milliamp stimulation to the exposed external branch of the superior laryngeal nerve, the RLN, and the vagus nerve, and record the EMG responses. To stimulate the indirect mapping and localizing of the nerve position before visual identification during surgery, apply one milliamp stimulation at the overlying fascia, and record the EMG responses. To confirm and compare the patterns of real time changes in a virtual laryngeal EMG signals during and after acute RLN traction injury, wrap a 1.3 milometer wide plastic vascular loop around the RLN, and apply retraction.

Using continuous enter operative neural monitoring to monitor the evoked laryngeal EMG signals. After the traction compression RLN injury, use hemostatic forceps to pinch the distal segment of the RLN to stimulate the nerve being inadvertently clamped due to visual misidentification as a vessel during the operation, and record the accompanying EMG signal change. To simulate a thermal injury, activate an energy-based device or EBD at a 5 millimeter distance away from the RLN, and record the EMG response.

Pre-gel transcutaneous and trans cartilage electrodes generally record lower EMG amplitudes, compared to EMG tube, and needle electrodes. Changes on the contact between EMG tube electrodes and vocal folds after tracheal displacements significantly changes the recorded EMG signals. When RLN traction stress is experimentally induced EMG tube electrodes on the vocalis muscle and trends cartilage urcutaneous, and transcutaneous electrodes record similar patterns of progressive degradation in EMG amplitude.

Typically real time EMG change monitoring during RLN and traction injury reveals the progressive amplitude decrease, combined with a latency increase that gradually recovers after traction release. all RLN'S demonstrate an immediate loss of signal after acute mechanical injury, and no gradual EMG recovery is observed within a short period of time after the injury. After thermal injury, the real time EMG reveals a combined event which then rapidly degrades to a loss of signal that may be related to the dose of thermal stress.

Although some date are inapplicable to clinical case, this spoken model provides available research preform, in guiding future experiments to optimize a use of intraoperative neuron monitoring, for the prevention of injuries, to our surgery. Although this measure can provide inside into the Surgey, it can also be used for educational training in clinical applications of inter operative neuron monitoring. Generally individuals.

Visual demonstration of this measure is critical. As the animal preparation and the assistant steps. In human surgeries.