This study was supported by grants from Kaohsiung Medical University Hospital, Kaohsiung Medical University (KMUH109-9M44), Kaohsiung Municipal Siaogang Hospital/Kaohsiung Medical University Research Center grants (KMHK-DK(C)110009, I-109-04, H-109-05, I-108-02), and Ministry of Science and Technology (MOST 109-2628-B-037-014, MOST 110-2314-B-037-104-MY2, MOST 110-2314-B-037-120), Taiwan.

The animal experiments were approved by the Institutional Animal Care and Use Committee (IACUC) of Kaohsiung Medical University, Taiwan (protocol no: IACUC-110082).
1. Animal preparation and anesthesia
<ol>
	<li>Conditions for porcine selection: Select Duroc-Landrace pigs at age of 3 to 4 months old and weighing 18 to 30 kg.</li>
	<li>Preparation before the experiment: Fast the pigs for 8 h without food and 2 h without water before anesthesia.</li>
	<li>Anesthesia induction: Administer 2 mg/kg Tiletamine/Zolazepam via intramuscular route 30 min before surgery 
	NOTE: Neuromuscular block agents were not used during anesthesia induction.</li>
	<li>Endotracheal tube selection: Use a 6.0 mm commercial electromyography (EMG) endotracheal tube (the recording electrodes) in the manner routinely used clinically.</li>
	<li>Intubation: Let the anesthesiologist intubate the recording electrodes with the assistance of direct laryngoscopy in the prone position. In this study, the endotracheal tube was fixed at 24 cm through end-tidal carbon dioxide (etCO2) monitoring and chest auscultation to ensure the appropriate tube location.</li>
	<li>Anesthesia maintenance: Position the pig on its back, extend the neck, and fix the endotracheal tube. Set the tidal volume to 8 to 12 mL/kg and a 15 to 20 breaths per minute respiratory rate. Use 1% to 2% sevoflurane for general anesthesia maintenance. 
	&#8203;NOTE: Neuromuscular block agents were not used during anesthesia maintenance.</li>
	<li>During the experiment, in addition to continuous monitoring of the animal&#39;s core body temperature, it is important to ensure that the experimental temperature is within an appropriate range. If the animal experiences a drop in body temperature, immediate thermal support such as a warm blanket should be provided.</li>
</ol>
2. Animal operation (Figure 1 and Figure 2)
<ol>
	<li>Verify a surgical plane of anesthesia.</li>
	<li>Skin incision: Make a 15 cm transverse cervical incision on the skin 1 cm above the sternum (Figure 1A).</li>
	<li>Raise the subplastysmal flap to the hyoid bone level.</li>
	<li>Separate the strap muscles via the midline approach, and retract laterally to visualize the thyroid cartilage, cricoid cartilage, tracheal rings, and thyroid gland. 
	NOTE: The edges of the strap muscles need to be dissected carefully and neatly for TG studies.</li>
	<li>After exposure, dissect the sternocleidomastoid muscles (SCMs) bilaterally (Figure 1B). 
	NOTE: The edges of the SCMs need to be dissected carefully and neatly for EP studies.</li>
	<li>Identify, expose, and dissect along the recurrent laryngeal nerves (RLNs) and vagus nerves (VNs) bilaterally (Figure 2). 
	NOTE: IONM can assist with this step.</li>
	<li>Perform the experiments of EP and TG studies following step 4 and step 5.</li>
	<li>After completing the whole experiment, keep the piglets under 4%-6% sevoflurane and humanely euthanize them by an overdose of Tiletamine/Zolazepam (6 mg/kg).</li>
</ol>
3. Surgical energy devices (SEDs) information and settings
<ol>
	<li>For the details regarding SEDs refer to the Table of Materials. 
	&#8203;NOTE: This study uses Advanced bipolar SEDs (referenced as Device A) to demonstrate the EP and TG studies.</li>
</ol>
4. Electrophysiological (EP) study
<ol>
	<li>Continuous IONM setting (Figure 3) 
	NOTE: Ensure that the recording electrodes are intubated as mentioned in step 1.5.
	<ol>
		<li>Install the ground electrodes outside the surgical incision wound.</li>
		<li>Install the stimulating electrodes: Install a 2.0 mm automatic periodic stimulation (APS) electrode on one side of the VN.</li>
		<li>Connect all electrodes on the interconnection box, and check that the interconnection box is connected to the monitoring system (Nerve Integrity Monitoring system) and that the power of the monitoring system is on (Figure 3A).</li>
		<li>Confirm that the monitoring system shows that the electrodes are connected correctly.</li>
		<li>Select the Monitoring page, and click on Advanced Settings.</li>
		<li>Click APS to set APS Stimulation to 1/min for slow rate, 1/s for fast rate, and Alarm Limits to 50% and 2000 &#181;V for amplitudes, 10% for latency. Then click on OK to finish the settings. 
		NOTE: The setting of other columns depends on the experimenter.</li>
		<li>Click on Events Capture in the Events column, and set the event threshold at 100 &#181;V. 
		NOTE: Figure 3B demonstrates the protocol steps 4.1.5-4.1.7.</li>
		<li>Find the Vagus APS Stim column, and set the current of stimulation at 1.0 mA. Click on Baseline; a new window, Establishing APS Baseline, will appear on the right side of the screen.</li>
		<li>Input the Session Title and Session Comments. Select the channel to be tested, and the system will automatically start to measure 20 times. The baseline amplitude and latency will be automatically calculated and shown. Click on Accept if the baseline is correct. 
		NOTE: Figure 3C demonstrates the protocol steps 4.1.8-4.1.9.</li>
		<li>Click on the Fast Forward icon in Vagus APS Stim column to start a test. After each EP experiment, click on the Pulse icon to stop recordings.</li>
		<li>Select the Reports page and set the report output format to save the file to USB. 
		NOTE: The sample C-IONM report is shown in Figure 3D.</li>
	</ol>
	</li>
	<li>EP activation study (Figure 4)
	<ol>
		<li>Develop experimental guidelines before starting an experiment. 
		NOTE: Figure 4A shows a common EP activation study protocol example, which can be adjusted according to SED characteristics. For some instruments with activation cycles, the single activation time is a single activation cycle, mostly ranging from 2-4 s. Most SEDs do not have an activation cycle, and the single activation time is 3 s.</li>
		<li>Activation distance tests at 5 mm:
		<ol>
			<li>Apply the SED on the soft tissue at a distance of 5 mm from the RLN and activate SED (single activation).</li>
			<li>Observe the EMG change. Operate at the same activation distance three times unless a substantial EMG amplitude change occurs. 
			NOTE: Figure 4B shows the activation distance test at 5 mm.</li>
		</ol>
		</li>
		<li>Activation distance tests at 2 mm:
		<ol>
			<li>Apply the SED on the soft tissue close to the RLN at 1 mm distance and activate SED (single activation).</li>
			<li>Observe the EMG change. Operate at the same activation distance three times unless a substantial EMG amplitude change occurs.</li>
		</ol>
		</li>
		<li>Activation distance tests at 1 mm:
		<ol>
			<li>Apply the SED on the soft tissue at a distance of 1 mm from the RLN, and activate SED (single activation).</li>
			<li>Observe the EMG change. Operate at the same activation distance three times unless a substantial EMG amplitude change occurs</li>
		</ol>
		</li>
		<li>If a substantial decrease of EMG amplitude is observed during steps 4.2.2-4.2.4, stop the RLN experiment. Record the real-time EMG continuously for 20-60 min to determine whether the injury is reversible. (Figure 4C)</li>
		<li>Manually record the experimental results as a table (Table 1).</li>
	</ol>
	</li>
	<li>EP cooling study (Figure 5)
	<ol>
		<li>Develop experimental guidelines before starting an experiment. 
		NOTE: Figure 5A shows a common EP cooling study protocol example, which can be adjusted according to SED characteristics.</li>
		<li>Cooling time tests of 5 s:
		<ol>
			<li>Apply SED single activation to the SCM muscle. Touch the RLN with the tip of the SED after 5 s of waiting and cooling.</li>
			<li>Observe the EMG change. Operate at the same cooling time three times unless a substantial EMG amplitude change occurs.</li>
		</ol>
		</li>
		<li>Cooling time tests of 2 s:
		<ol>
			<li>Apply SED single activation to the SCM muscle. Touch the RLN with the tip of the SED after 2 s of waiting and cooling.</li>
			<li>Observe the EMG change. Operate at the same cooling time three times unless a substantial EMG amplitude change occurs. 
			NOTE: Figure 5B shows the cooling time test of 2 s.</li>
		</ol>
		</li>
		<li>Proceed immediately with muscle touch maneuver (MTM) tests:
		<ol>
			<li>Apply SED single activation to the SCM muscle. Quickly touch (approximately 1 s) the activated surface of the SED with another position of the SCM (MTM, Figure 5C).</li>
			<li>Touch the RLN with the tip of the SED immediately after MTM and observe the EMG change. Operate at the same cooling time three times unless a substantial EMG amplitude change occurs.</li>
		</ol>
		</li>
		<li>Proceed immediately without muscle touch maneuver (MTM) tests:
		<ol>
			<li>Apply SED single activation to the SCM muscle. Touch the RLN with the tip of the SED immediately without MTM.</li>
			<li>Observe the EMG change. Operate the same cooling time three times unless a substantial EMG amplitude change occurs. If a substantial decrease of EMG amplitude is observed, follow step 4.3.6.</li>
		</ol>
		</li>
		<li>If a substantial decrease of EMG amplitude is observed, stop the RLN experiment. Then, continuously monitor the real-time EMG response for at least 20 min to determine whether the RLN injury is reversible or not. (Figure 5D)</li>
		<li>Manually record the experimental results as a table (Table 2).</li>
	</ol>
	</li>
</ol>
5. Thermographic (TG) study
<ol>
	<li>Set up the thermal imaging system (Figure 6). 
	NOTE: Thermal imaging camera with temperature sensitivity up to a temperature range of -20 &#176;C to 650 &#176;C. The image is updated every second.
	<ol>
		<li>Place the camera 50 cm from the target tissue at an angle of 60&#176; from the experimental table (Figure 6A). 
		NOTE: In the operating field, measured by a thermal imaging camera, the temperature is displayed according to the color scale. The location with the highest temperature on the screen is marked with a &#34;+&#34; sign, and its corresponding temperature is displayed (Figure 6B)</li>
		<li>Select Video Mode, and press the capture button. 
		NOTE: The procedures monitored by the thermal camera are continuously recorded in video form.</li>
	</ol>
	</li>
	<li>Conduct the animal preparation for the TG study:
	<ol>
		<li>Record the background temperature of the experimental area using the thermal imaging camera. The background temperature should be in the range of 25 &#177; 2 &#176;C (Figure 6C). If the background temperature exceeds this range, adjust the temperature of the laboratory air conditioner and test again.</li>
		<li>Standard strap muscle thickness for SED activation: Prepare the strap muscles for the TG study as described in step 2.3. The standard strap muscle thickness for SED activation is 5 mm (Figure 6D).</li>
	</ol>
	</li>
	<li>TG activation study (Figure 6 and Figure 7)
	<ol>
		<li>Dry environment tests: Wipe the surface of porcine strap muscles with dry gauze.
		<ol>
			<li>Whole blade tests in a dry environment (Figure 7A):
			<ol>
				<li>Grasp the strap muscle at the full length of the blade using SED (Figure 6E).</li>
				<li>Evaluate maximum activation temperature: After a single activation, the maximum temperature is shown on the screen during the measurement (Figure 7B).</li>
				<li>Evaluate lateral thermal spread: Measure the diameter of the 60 &#176;C isothermal line after a single activation.</li>
				<li>Evaluate smoke and splashing: After a single activation, when the highest temperature on the screen exceeds 60 &#176;C, record any smoke and splash on the screen. Repeat five measurements in different areas. 
				NOTE: Maximum activation temperature was evaluated with whole blade tests in a dry environment only.</li>
			</ol>
			</li>
			<li>One-third (1/3) of blade tests in a dry environment (Figure 7C):
			<ol>
				<li>Grasp the strap muscle with an anterior 1/3-length blade using SED (Figure 6F). Evaluate the lateral thermal spread, smoke, and splashing (Figure 7D) as described in step 5.3.1.1. Repeat five measurements in different areas.</li>
			</ol>
			</li>
		</ol>
		</li>
		<li>Wet environment tests: Soak the porcine strap muscles in sterile water for 3 s just before SED activation.
		<ol>
			<li>Whole blade tests in a wet environment (Figure 7E): Grasp the strap muscle at full length of the blade using SED and evaluate the lateral thermal spread (Figure 7F), smoke, and splashing as described in step 5.3.1.1. Repeat five measurements in different areas.</li>
			<li>One-third (1/3) tests in a wet environment (Figure 7G): Grasp the strap muscle with an anterior 1/3-length blade using SED and evaluate the lateral thermal spread, smoke (Figure 7H), and splashing as described in step 5.3.1.1. Repeat five measurements at different areas.</li>
		</ol>
		</li>
		<li>Manually record the experimental results as a table (Table 3).</li>
	</ol>
	</li>
	<li>TG cooling study (Figure 8)
	<ol>
		<li>Dry environment: Wipe the surface of porcine strap muscles with dry gauze as in step 5.3.1. 
		NOTE: In the TG cooling study, all activations were performed in a dry environment with whole blade activation.</li>
		<li>Evaluate minimum cooling time without MTM: After SED single activation with the whole blade on strap muscle, start recording the cooling time until the highest temperature on the screen was less than 60 &#176;C. Repeat five measurements in different areas. 
		NOTE: When measuring the cooling time and temperature of the SED blade after single activation and MTM, cover the SED-activated muscle area and the MTM-contacting muscle area with gauze, as the high temperature in these areas will be detected up on the TG screen and interfere with the temperature that is to be actually measured.</li>
		<li>Evaluate the blade temperature after MTM: After a single activation of the SED with the whole blade on the strap muscle, quickly touch (~1 s) the activated surface of the SED with another position of the strap muscle (Figure 8A). Then record its temperature immediately after leaving the SED from the strap muscle with the blade open (Figure 8B).</li>
		<li>Evaluate the minimum cooling time with MTM: After step 5.4.3, when the temperature is more than 60 &#176;C, start recording the cooling time until the highest temperature on the screen is less than 60 &#176;C. Repeat five measurements in different areas.</li>
		<li>Manually record the experimental results as a table (Table 4).</li>
	</ol>
	</li>
</ol>
6. Data interpretations
<ol>
	<li>Present the EP and TG safety parameters in table form with smoke and splashing marked. 
	NOTE: Here, the EP and TG safety parameters of SED are presented in table form, and smoke and splashing are marked with * and # symbols, respectively. In EP and TG studies, the final result lists the maximum data as in Table 5.</li>
</ol>

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

The development of SEDs is based on the expectation of thyroid surgeons to achieve effective hemostasis during thyroid surgery. However, the high temperature generated by SED is a risk factor that cannot be ignored. As the use of SED becomes more common, thermal injury to nerves will also become more common. Therefore, it is the responsibility of the thyroid surgeons who use SED to understand how to safely operate the equipment. However, it is not advisable to verify safety parameters through trial and error repeatedly in humans; therefore, the value of animal experiments has been shown. In addition, a standardized process is necessary to qualify and quantify the possible thermal effects of SEDs15,17 to maximally provide thyroid surgeons with guidelines to safely perform operations.
In this study, several steps require more attention. In the EP studies, neuromuscular blockade agents could interfere with EMG signals during neural monitoring and were not used during anesthesia induction and maintenance. In the TG studies, heat sources other than the SED tests should be removed. When the heat sources cannot be removed (e.g., the activation area for cooling study or strap muscle after MTM), it is necessary to block the non-tested heat sources with gauze. In the TG studies, the temperature of SEDs before activation should be confirmed to be within the background reference temperature (25 &#177; 2 &#176;C), otherwise, a cooling measure should be taken, and the blade should be determined to be dry before starting the experiment.
Several previous studies have contributed to the definition of EP15,37,38,39,40,41,42,43&#160;and TG31,32&#160;safety parameters of various SEDs in activation and cooling studies in various porcine thyroid surgery models. The current protocol not only integrates past experience but also further optimizes and standardizes the process. In the EP study, once SED was activated without a safe critical distance or safe cooling time, the nerves faced irreversible and rapid injury. In the TG study, we observed the 60 &#176;C isothermal field and the production of smoke/splashing. Surgeons can better understand the thermal spread patterns in different activation environments and different grasping ranges.
This study still has a few limitations. First, the temperature in the environment is not the same as in the surgical room, and the temperature of the piglet is not the same as the body temperature of a human. Second, the results of the porcine model may not be applicable to all human clinical practices; the animal experimental study not only provides surgeons with SED information that cannot be obtained from humans but also serves as a valuable research platform to establish thermal injury information for newly developed SEDs in the future. This information can help surgeons choose instruments and surgical strategies that can reduce thermal injury during thyroid and parathyroid surgery.
This article demonstrates the standard procedure for using animal experiments so that thyroid surgeons can gain a more comprehensive understanding of (1) the safe activation distance and cooling time for SEDs, (2) the maximum temperature generated by SEDs activation, and (3) irregular lateral thermal spread and smoke/splashing, which may potentially injure the nerve.

Efficient hemostasis is a very important issue in thyroid and parathyroid surgery. In recent decades, one of the most major advances in thyroid and parathyroid surgery has been the development of surgical energy devices (SEDs)1. SEDs provide more efficient hemostasis than the conventional clamp-and-tie technique in areas with rich blood supply, which reduces intraoperative blood loss and operation time2, postoperative hypocalcemia3, and life-threatening postoperative hematoma4. SEDs are reported to be used in 65.7% of thyroidectomy patients in recent studies5, and the annual use of SED increases each year.
However, SEDs have not been proven superior to conventional techniques in terms of recurrent laryngeal nerve (RLN) injury in thyroid and parathyroid surgery4,6,7. Thermal injury and lateral thermal spread to the RLN often occur unexpectedly when a SED is activated near the nerve, and this type of injury is usually severe and irreversible. Compared to mechanical traction or compression nerve injury, thermally nerve injury has less distortion of the outer structure but more severe damage to the inner endoneurium, including the myelin sheath and the axon8,9,10,11. This kind of injury not only experiences difficulty in regaining normal function but also is less reversible in clinical sequence than traction injury10,12. In addition, thermal injury is often invisible to the surgeon and may be unrecognized in the course of surgery13,14. Thus, surgeons should consider the thermal effects of SED to avoid RLN thermal injury during thyroid and parathyroid surgery.
Porcine models are most commonly used for RLN research because the anatomy and physiology of pigs are very similar to those of humans15,16,17,18,19,20. The experimental porcine model enables easy handling, is widely available, and is cost-effective9. For electrophysiological (EP) information, intraoperative neuromonitoring (IONM) is helpful for detecting mechanisms of nerve injury and predicting postoperative vocal cord function21,22,23,24,25,26,27. Addirionally, continuous IONM (CIONM) enables early detection of nerve injury after high-risk procedures because it can immediately feedback for the nerve function by using repetitive vagal stimulation28,29,30. Studies on EP activation and cooling can determine the safe SED activation distance from the RLN and the safe cooling time after SED activation before contacting the RLN. For thermographic&#160;information, a thermal imaging camera is helpful to evaluate the temperature change (activation and cooling), and the hyperthermal region can be visualized after SED activations31,32,33,34,35. In a previous study, RLN thermal injury occurred when the tissue temperature reached the critical temperature of 60 &#176;C in the porcine CIONM model36. Studies on TG activation and cooling can determine the lateral thermal spread distance, the occurrence of smoke and splashing, and the temperature change during cooling with or without the muscle touch maneuver (MTM). To safely apply SED in thyroid/parathyroid surgery, this article introduces an experimental porcine model study to investigate EP and TG safety parameters of SEDs under standardized procedures.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Automatic periodic stimulation (APS)</td>
			<td>Medtronic, Jacksonville, FL</td>
			<td></td>
			<td>2.0 mm</td>
		</tr>
		<tr>
			<td>Advanced bipolar surgical energy devices(SEDs)</td>
			<td>Medtronic, Minneapolis, MN</td>
			<td>LigaSure Exact Dissector (Device A)</td>
			<td>Generator: Valleylab LS10 energy platform 
			Power setting: Default</td>
		</tr>
		<tr>
			<td>Bipolar electrocautery</td>
			<td></td>
			<td></td>
			<td>Generator: ForceTriad energy platform 
			Power setting: 30 watts</td>
		</tr>
		<tr>
			<td>Duroc-Landrace pigs</td>
			<td></td>
			<td></td>
			<td>3&#8211;4 months old; weighing 18&#8211;30 kg</td>
		</tr>
		<tr>
			<td>Electromyography (EMG) Endotracheal tube (ETT)</td>
			<td>Medtronic, Jacksonville, FL</td>
			<td>#6 NIM Standard Tube&#160;</td>
			<td>Recording electrodes</td>
		</tr>
		<tr>
			<td>Ferromagnetic SEDs</td>
			<td>Domain Surgical, Salt Lake City, Utah</td>
			<td>FMwand, and Fmsealer</td>
			<td>Generator: FMX G1 Generator 
			Power setting: FMwand (Max 45); FMsealer (Max 3)</td>
		</tr>
		<tr>
			<td>Hybrid SEDs 
			(Ultrasonic and Advance bipolar SEDs)</td>
			<td>Olympus Co Inc, Tokyo, Japan</td>
			<td>Thunderbeat</td>
			<td>Generator: Thunderbeat generator ESG USG 400 
			Power setting: SEAL&#38;CUT mode (Level 1); SEAL mode (Level 3)</td>
		</tr>
		<tr>
			<td>Monopolar electrocautery&#160;</td>
			<td></td>
			<td></td>
			<td>Generator: ForceTriad energy platform 
			Power setting: 15 watts</td>
		</tr>
		<tr>
			<td>Nerve Integrity Monitoring (NIM) system&#160;</td>
			<td>Medtronic, Jacksonville, FL</td>
			<td>NIM 3.0&#160;</td>
			<td>Intraoperative neuromonitoring (IONM) equipment</td>
		</tr>
		<tr>
			<td>Sevoflurane</td>
			<td></td>
			<td></td>
			<td>1% to 2% for anesthesia maintenance</td>
		</tr>
		<tr>
			<td>Tiletamine/Zolazepam</td>
			<td></td>
			<td></td>
			<td>2 mg/kg for anesthesia induction</td>
		</tr>
		<tr>
			<td>Thermal imaging camera</td>
			<td>Ezo Corp., Taiwan</td>
			<td>Thermal camera D4A (384x288 pixels)</td>
			<td>Thermal image recording equioments</td>
		</tr>
		<tr>
			<td>Ultrasonic SEDs</td>
			<td>Ethicon, Johnson and Johnson, Cincinnati, OH</td>
			<td>Harmonic Focus+</td>
			<td>Generator: Ethicon Endo-Surgery Generator G11 
			Power setting: Level 5</td>
		</tr>
		<tr>
			<td>Ultrasonic SEDs</td>
			<td>Medtronic, Minneapolis, MN</td>
			<td>Sonicision&#160;</td>
			<td>Generator: Sonicision Reusable Generator 
			Power setting: maximum power mode (55 kHz)</td>
		</tr>
	</tbody>
</table>

investigation of the electrophysiological and thermographic safety parameters of surgical energy devices during thyroid and parathyroid surgery in a porcine model

In thyroid and parathyroid surgery, surgical energy devices (SEDs) provide more efficient hemostasis than conventional clamp-and-tie hemostasis in areas with rich blood supply. However, when a SED is activated near the recurrent laryngeal nerve (RLN), the heat generated by the SED may injure the nerve irreversibly. To safely apply SEDs in thyroid/parathyroid surgery, this article introduces experimental porcine model studies to investigate the activation and cooling safety parameters of SEDs in standardized electrophysiological (EP) and thermographic (TG) procedures, respectively. In the EP safety parameter experiments, continuous intraoperative neuromonitoring (C-IONM) is applied to demonstrate the RLN function in real-time. The EP activation study evaluates the safe activation distance of SEDs; the EP cooling study evaluates the safe cooling time of SEDs. In the TG safety parameter experiment, a thermal imaging camera is used to record the temperature change after activating the SED. The TG activation study evaluates the lateral thermal spread distance after SED activation in a dry or humid environment and whether smoke and splashing are generated; the TG cooling study evaluates the cooling time. This will help establish the safety parameters of newly developed SEDs used in thyroid/parathyroid surgery and provide safety guidelines to avoid RLN injury and related complications.

Watch this Scientific Journal Video about Investigation of the Electrophysiological and Thermographic Safety Parameters of Surgical Energy Devices During Thyroid and Parathyroid Surgery in a Porcine M

Investigation of the Electrophysiological and Thermographic Safety Parameters of Surgical Energy Devices During Thyroid and Parathyroid Surgery in a Porcine Model

The safe application of newly developed surgical energy devices in thyroid/parathyroid surgery attracts the attention of surgeons. Animal experimental models can avoid unnecessary trials and errors in human surgery. This report aims to demonstrate electrophysiological and thermographic methods to evaluate the safety parameters of SEDs in thyroid/parathyroid surgery.

In thyroid and parathyroid surgery, surgical energy devices (SEDs) provide more efficient hemostasis than conventional clamp-and-tie hemostasis in areas ...

investigation-electrophysiological-thermographic-safety-parameters

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JoVE Journal

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1.4K Views.  Kaohsiung Medical University. The safe application of newly developed surgical energy devices in thyroid/parathyroid surgery attracts the attention of surgeons. Animal experimental models can avoid unnecessary trials and errors in human surgery. This report aims to demonstrate electrophysiological and thermographic methods to evaluate the safety parameters of SEDs in thyroid/parathyroid surgery. 

Video: Investigation of the Electrophysiological and Thermographic Safety Parameters of Surgical Energy Devices During Thyroid and Parathyroid Surgery in a Porcine Model

Heterotopic Renal Autotransplantation in a Porcine Model: A Step-by-Step Protocol

Kidney transplantation is the treatment of choice for patients suffering from end-stage renal disease. It offers better life expectancy and higher quality of life when compared to dialysis. Although the last few decades have seen major improvements in patient outcomes following kidney transplantation, the increasing shortage of available organs represents a severe problem worldwide. To expand the donor pool, marginal kidney grafts recovered from extended criteria donors (ECD) or donated after circulatory death (DCD) are now accepted for transplantation. To further improve the postoperative outcome of these marginal grafts, research must focus on new therapeutic approaches such as alternative preservation techniques, immunomodulation, gene transfer, and stem cell administration.
Experimental studies in animal models are the final step before newly developed techniques can be translated into clinical practice. Porcine kidney transplantation is an excellent model of human transplantation and allows investigation of novel approaches. The major advantage of the porcine model is its anatomical and physiological similarity to the human body, which facilitates the rapid translation of new findings to clinical trials. This article offers a surgical step-by-step protocol for an autotransplantation model and highlights key factors to ensure experimental success. Adequate pre- and postoperative housing, attentive anesthesia, and consistent surgical techniques result in favorable postoperative outcomes. Resection of the contralateral native kidney provides the opportunity to assess post-transplant graft function. The placement of venous and urinary catheters and the use of metabolic cages allow further detailed evaluation. For long-term follow-up studies and investigation of alternative graft preservation techniques, autotransplantation models are superior to allotransplantation models, as they avoid the confounding bias posed by rejection and immunosuppressive medication.

Porcine models of organ transplantation provide an important platform to study mechanisms of organ preservation. This article describes a heterotopic porcine renal autotransplantation model, which allows investigating new approaches to improve the outcome of transplantation using marginal kidney grafts.

Kidney transplantation is the treatment of choice for patients suffering from end-stage renal disease. It offers better life expectancy and higher quality ...

Surgical Angiogenesis in Porcine Tibial Allotransplantation: A New Large Animal Bone Vascularized Composite Allotransplantation Model

Segmental bone loss resulting from trauma, infection malignancy and congenital anomaly remains a major reconstructive challenge. Current therapeutic options have significant risk of failure and substantial morbidity.
Use of bone vascularized composite allotransplantation (VCA) would offer both a close match of resected bone size and shape and the healing and remodeling potential of living bone. At present, life-long drug immunosuppression (IS) is required. Organ toxicity, opportunistic infection and neoplasm risks are of concern to treat such non-lethal indications.
We have previously demonstrated that bone and joint VCA viability may be maintained in rats and rabbits without the need of long-term-immunosuppression by implantation of recipient derived vessels within the VCA. It generates an autogenous, neoangiogenic circulation with measurable flow and active bone remodeling, requiring only 2 weeks of IS. As small animals differ from man substantially in anatomy, bone physiology and immunology, we have developed a porcine bone VCA model to evaluate this technique before clinical application is undertaken. Miniature swine are currently widely used for allotransplantation research, given their immunologic, anatomic, physiologic and size similarities to man. Here, we describe a new porcine orthotopic tibial bone VCA model to test the role of autogenous surgical angiogenesis to maintain VCA viability.
The model reconstructs segmental tibial bone defects using size- and shape-matched allogeneic tibial bone segments, transplanted across a major swine leukocyte antigen (SLA) mismatch in Yucatan miniature swine. Nutrient vessel repair and implantation of recipient derived autogenous vessels into the medullary canal of allogeneic tibial bone segments is performed in combination with simultaneous short-term IS. This permits a neoangiogenic autogenous circulation to develop from the implanted tissue, maintaining flow through the allogeneic nutrient vessels for a short time. Once established, the new autogenous circulation maintains bone viability following cessation of drug therapy and subsequent nutrient vessel thrombosis.

Currently any kind of vascularized composite allotransplantation depends on long-term-immunosuppression, difficult to support for non-life-critical indications. We present a new porcine tibial VCA model that can be used to study bone VCA and demonstrate the use of surgical angiogenesis to maintain bone viability without the need of long-term immune-modulation.

Segmental bone loss resulting from trauma, infection malignancy and congenital anomaly remains a major reconstructive challenge. Current therapeutic ...

Use of Two Intracorporeal Ventricular Assist Devices As a Total Artificial Heart

Mechanical circulatory support (MCS) has been introduced as a viable alternative to heart transplantation primarily through the use of intracorporeal ventricular assist devices (VADs) for support of the left ventricle. However, certain clinical scenarios warrant biventricular mechanical support. One strategy for some patients is the excision of both ventricles and the implantation of two VAD pumps as a total artificial heart (TAH). This has recently been made possible by the improvements in device design and the small profile of centrifugal devices. This TAH approach remains experimental with many important challenges such as the device settings to balance the right and left circulation, the orientation of the devices and the outflow graft with their influence on hemolysis and stability, and the outcome of chronic support using such an orientation. This protocol aims to provide a reproducible approach for total artificial heart replacement with two intracorporeal centrifugal VADs in a cow model.

Here, we present a protocol using two centrifugal pumps as a total artificial heart replacement.

Mechanical circulatory support (MCS) has been introduced as a viable alternative to heart transplantation primarily through the use of intracorporeal ...

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

Intraoperative injury to the recurrent laryngeal nerve (RLN) can cause vocal cord paralysis, which interferes with speech and can potentially interfere with breathing. In recent years, intraoperative neural monitoring (IONM) has been widely adapted as an adjunct technique to localize the RLN, detect RLN injury, and predict vocal cord function during the operations. Many studies have also used animal models to investigate new applications of IONM technology and to develop reliable strategies for preventing intraoperative RLN injury. The aim of this article is to introduce a standard protocol for using a porcine model in IONM research. The article demonstrates the procedures for inducing general anesthesia, performing tracheal intubation, and experimental design to investigate the electrophysiological characteristics of RLN injuries. Applications of this protocol can improve overall efficacy in implementing the 3R principle (replacement, reduction and refinement) in porcine IONM studies.

This study aims to develop a standard protocol of intra-operative neural monitoring of thyroid surgery in a porcine model. Here, we present a protocol to demonstrate general anesthesia, to compare different types of electrodes, and to investigate the electrophysiological characteristics of the normal and injured recurrent laryngeal nerves.

Intraoperative injury to the recurrent laryngeal nerve (RLN) can cause vocal cord paralysis, which interferes with speech and can potentially interfere ...

An In Vivo Mouse Model of Total Intravenous Anesthesia During Cancer Resection Surgery

Anesthesia is a routine component of cancer care that is used for diagnostic and therapeutic procedures. The anesthetic technique has recently been implicated in impacting long-term cancer outcomes, possibly through modulation of adrenergic-inflammatory responses that impact cancer cell behavior and immune cell function. Emerging evidence suggests that propofol-based total intravenous anesthesia (TIVA) may be beneficial for long-term cancer outcomes when compared to inhaled volatile anesthesia. However, the available clinical findings are inconsistent. Preclinical studies that identify the underlying mechanisms involved are critically needed to guide the design of clinical studies that will expedite insight. Most preclinical models of anesthesia have been extrapolated from the use of anesthesia in in vivo research and are not optimally designed to study the impact of anesthesia itself as the primary endpoint. This paper describes a method for delivering propofol-TIVA anesthesia in a mouse model of breast cancer resection that replicates key aspects of clinical delivery in cancer patients. The model can be used to study mechanisms of action of anesthesia on cancer outcomes in diverse cancer types and can be extrapolated to other non-cancer areas of preclinical anesthesia research.

An In Vivo Mouse Model of Total Intravenous Anesthesia During Cancer Resection Surgery

This paper describes a method for modeling total intravenous anesthesia (TIVA) during cancer resection surgery in mice. The goal is to replicate key features of anesthesia delivery to patients with cancer. The method allows investigation of how anesthetic technique affects cancer recurrence after resection surgery.

Anesthesia is a routine component of cancer care that is used for diagnostic and therapeutic procedures. The anesthetic technique has recently been ...

Left Lung Orthotopic Transplantation in a Juvenile Porcine Model for ESLP

Lung transplantation is the gold-standard treatment for end-stage lung disease, with over 4,600 lung transplantations performed worldwide annually. However, lung transplantation is limited by a shortage of available donor organs. As such, there is high waitlist mortality. Ex situ lung perfusion (ESLP) has increased donor lung utilization rates in some centers by 15%-20%. ESLP has been applied as a method to assess and recondition marginal donor lungs and has demonstrated acceptable short- and long-term outcomes following transplantation of extended criteria donor (ECD) lungs. Large animal (in vivo) transplantation models are required to validate ongoing in vitro research findings. Anatomic and physiologic differences between humans and pigs pose significant technical and anesthetic challenges. An easily reproducible transplant model would permit the&#160;in vivo&#160;validation of current ESLP strategies and the preclinical evaluation of various interventions designed to improve donor lung function. This protocol describes a porcine model of orthotopic left lung allotransplantation. This includes anesthetic and surgical techniques, a customized surgical checklist, troubleshooting, modifications, and the benefits and limitations of the approach.

This protocol describes a juvenile porcine model of orthotopic left lung allotransplantation designed for use with ESLP research. Focus is made on anesthetic and surgical techniques, as well as critical steps and troubleshooting.

Lung transplantation is the gold-standard treatment for end-stage lung disease, with over 4,600 lung transplantations performed worldwide annually. ...

Establishment and Evaluation of a Porcine Vein Graft Disease Model

Venous graft disease (VGD) is the leading cause of coronary artery bypass graft (CABG) failure. Large animal models of CABG-VGD are needed for the investigation of disease mechanisms and the development of therapeutic strategies. 
To perform the surgery, we enter the cardiac chamber through the third intercostal space and carefully dissect the internal mammary vein and immerse it in normal saline. The right main coronary artery is then treated for ischemia. The target vessel is incised, a shunt plug is placed, and the distal end of the graft vein is anastomosed. The ascending aorta is partially blocked, and the proximal end of the graft vein is anastomosed after perforation. The graft vein is checked for patency, and the proximal right coronary artery is ligated. 
CABG surgery is performed in minipigs to harvest the left internal mammary vein for its use as a vascular graft. Serum biochemical tests are used to evaluate the physiological status of the animals after surgery. Ultrasound examination shows that the proximal, middle, and distal end of the graft vessel are unobstructed. In the surgical model, turbulent blood flow in the graft is observed upon histological examination after the CABG surgery, and venous graft stenosis associated with intimal hyperplasia is observed in the graft. The study here provides detailed surgical procedures for the establishment of a repeatable CABG-induced VGD model.

In this protocol, novel pig vein bypass grafting was performed through a small incision in the left chest wall without cardiopulmonary bypass. A postoperative pathology study was done, which showed intimal thickening.

Venous graft disease (VGD) is the leading cause of coronary artery bypass graft (CABG) failure. Large animal models of CABG-VGD are needed for the ...

Establishment of a Simple and Effective Rat Model for Intraoperative Parathyroid Gland Imaging

Parathyroid gland (PG) identification is a critical unmet need in thyroidectomy. The identification of the PG is challenging in thyroid surgery as it is similar in color to the thyroid gland. The lack of effective animal models in preclinical research is a severe limitation for the development of PG identification techniques. This protocol allows for the establishment of a simple and effective rat model for PG identification. In this model, black iron oxide nanoparticles (IONPs) are injected locally in the thyroid gland and rapidly diffuse within the thyroid gland but not the PG. A negatively stained PG and a positively stained thyroid gland can be easily identified by the naked eye without requiring external microscopes. The position of the PG can be identified by increasing the color contrast between the thyroid gland and the PG, based on the color of the black IONPs. This rat model is low-cost and convenient for PG identification, and the IONPs are a novel PG contrast agent.

To date, the development of parathyroid gland (PG) identification methods is limited by the lack of animal models in preclinical research. Here, we establish a simple and effective rat model for intraoperative PG imaging and evaluate its effectiveness by using iron oxide nanoparticles as a novel PG contrast agent.

Parathyroid gland (PG) identification is a critical unmet need in thyroidectomy. The identification of the PG is challenging in thyroid surgery as it is ...

Delivery of Cardioactive Therapeutics in a Porcine Myocardial Infarction Model

Myocardial infarction is one of the leading causes of death and disability worldwide, and there is an urgent need for novel cardioprotective or regenerative strategies. An essential component of drug development is determining how a novel therapeutic is to be administered. Physiologically relevant large animal models are of critical importance in assessing the feasibility and efficacy of various therapeutic delivery strategies. Due to their similarities to humans in cardiovascular physiology, coronary vascular anatomy, and heart weight to body weight ratio, swine is one of the preferred species in the preclinical evaluation of new therapies for myocardial infarction. The present protocol describes three methods of administering cardioactive therapeutic agents in a porcine model. After percutaneously induced myocardial infarction, female landrace swine received treatment with novel agents through either: (1) thoracotomy and transepicardial injection, (2) catheter-based transendocardial injection, or (3) intravenous infusion via jugular vein osmotic minipump. The procedures employed for each technique are reproducible, resulting in reliable cardioactive drug delivery. These models can be easily adapted to suit individual study designs, and each of these delivery techniques can be used to investigate a variety of possible interventions. Therefore, these methods are a useful tool for translational scientists pursuing novel biological approaches in cardiac repair following myocardial infarction.

The present protocol describes three methods of administering cardioactive therapeutic agents in a porcine model. Female landrace swine received treatment through either: (1) thoracotomy and transepicardial injection, (2) catheter-based transendocardial injection, or (3) intravenous infusion via jugular vein osmotic minipump.

Myocardial infarction is one of the leading causes of death and disability worldwide, and there is an urgent need for novel cardioprotective or ...

A Personalized 3D-Printed Model for Preoperative Evaluation in Thyroid Surgery

The anatomic structure of the surgical area of thyroid cancer is complex. It is very important to comprehensively and carefully evaluate the tumor location and its relation with the capsule, trachea, esophagus, nerves, and blood vessels before operation. This paper introduces an innovative 3D-printed model establishment method based on computerized tomography (CT) DICOM images. We established a personalized 3D-printed model of the cervical thyroid surgery field for each patient who needed thyroid surgery to help clinicians evaluate the key points and difficulties of the surgery and select the operation methods of key parts as a basis. The results showed that this model is conducive to preoperative discussion and the formulation of operation strategies. In particular, as a result of the clear display of the recurrent laryngeal nerve and parathyroid gland locations in the thyroid operation field, injury to them can be avoided during surgery, the difficulty of thyroid surgery reduced, and the incidence of postoperative hypoparathyroidism and complications related to recurrent laryngeal nerve injury reduced too. Moreover, this 3D-printed model is intuitive and aids communication for the signing of informed consent by patients before surgery.

Here, a new method of establishing a personalized 3D-printed model for preoperative evaluation of thyroid surgery is proposed. It is conducive to preoperative discussion, reducing the difficulty of thyroid surgery.