The authors want to thank Dagmar Dirvonskis for her excellent technical support.

The experiments in this protocol were approved by the State and Institutional Animal Care Committee (Landesuntersuchungsamt Rheinland-Pfalz, Koblenz, Germany; approval no. G20-1-135). The experiments were conducted following the ARRIVE guidelines. Overall, 10 anesthetized male pigs (Sus scrofa domestica) with a mean weight of 30 kg &#177; 2 kg and 12-16 weeks in age were used for the present study.
1. Animal preparation
<ol>
	<li>Maintain a normal environment for the animals to minimize stress. Withhold food 6 h before the scheduled experiment to lower the risk of aspiration, but allow access to water.</li>
	<li>Sedate the pigs with a combined injection of midazolam (0.5 mg/kg) and azaperone (2-3 mg/kg) (see Table of Materials) in the gluteal muscle or neck with a needle (20 G) for intramuscular injection. Leave the animals undisturbed until sedation sets in (15-20 min). 
	NOTE: Depending on national regulations, the administration of sedating agents may be subject to scrutiny and may or may not require the supervision of a trained veterinarian. Consult with the local authorities before planning the experiments.</li>
	<li>Transport the sedated animals from the stables to the laboratory. The transport time must not exceed adequate sedation time (here, 30-60 min). Ensure sufficient heat retention so that the animal does not get hypothermic (i.e., below 38 &#176;C), such as by covering the body with a blanket depending on the outside temperature.</li>
	<li>Using a sensor (see Table of Materials) clipped to the ear or tail, monitor the peripheral oxygen saturation (SpO2).</li>
	<li>Disinfect the skin with a disinfectant (alcoholic) before inserting a peripheral vein cannula (22 G) into an ear vein. Spray the area, wipe once, then spray again, and allow the disinfectant to dry. Secure the ear cannula with a band-aid (See Table of Materials).</li>
</ol>
2. Anesthesia and mechanical ventilation
<ol>
	<li>Administer analgesia through an intravenous injection of 4 &#181;g/kg of fentanyl. Induce anesthesia with an intravenous injection of 3 mg/kg of propofol (see Table of Materials). 
	NOTE: Due to the bolus application, the drug quickly floods into the active compartment, providing a fast onset of deep anesthesia.</li>
	<li>Place the pig on a stretcher in a supine position and fix it with bandages. Apply muscle relaxant through an intravenous injection of 0.5 mg/kg of atracurium (see Table of Materials).</li>
	<li>Instantaneously start noninvasive ventilation via a dog ventilation mask (see Table of Materials) or similar models. To ensure a tight fit of the mask, place the thenar eminence and the thumbs of both hands on top of the mask while performing jaw thrust with the remaining fingers. 
	NOTE: Ventilation parameters: FiO2 (inspiratory oxygen fraction) = 100%, peak inspiratory pressure = &#60;20 cmH20, respiratory rate = 18-20 breaths/min, PEEP (positive end-expiratory pressure) = 5 cmH20.</li>
	<li>Maintain anesthesia through continuous infusion of 0.1-0.2 mg/kg/h of fentanyl and 8-12 mg/kg/h of propofol. Start infusing with 5 mL/kg/h of balanced electrolyte solution (see Table of Materials) continuously. Constantly maintain an adequate depth of anesthesia. 
	&#8203;NOTE: Surrogate parameters for this are the absence of movement, the lack of own respiratory efforts after intubation, and the absence of a sudden increase in heart rate. If possible, avoid permanent muscle relaxation to enable motor reactions as a sign of insufficient depth of anesthesia.</li>
</ol>
3. Endotracheal intubation
<ol>
	<li>Have an assistant stand on the left side of the head. Have the assistant&#39;s left hand open the mouth and pinch the tongue outward and left with a compress. Ask the assistant to press down on the right upper lip with the right index finger to provide a better mouth opening.</li>
	<li>Perform direct laryngoscopy. To do this, insert the laryngoscope (see Table of Materials) into the right side of the mouth and push it forward while pushing the tongue to the left. Advance the tip of the laryngoscope until it rests in the epiglottic vallecula. 
	NOTE: The epiglottis usually obscures the glottis by sticking to the soft palate.</li>
	<li>Carefully push the epiglottis aside with a tube guiding wire (see Table of Materials) with a gentle scooping motion from the right piriform recess to the left along the soft palate.</li>
	<li>Pass the handle of the laryngoscope to the assistant to fix it in the current position.</li>
	<li>Now, take the flexible intubation endoscope onto which an endotracheal tube has already been mounted and that is connected to a video monitor. Insert the endoscope orally and advance it over the base of the tongue until the glottis is visualized. 
	NOTE: To avoid fogging of the camera, the prior application of anti-fogging agents (see Table of Materials) is recommended.</li>
	<li>Advance the endoscope between the vocal ligaments into the trachea. Confirm the anatomy of the trachea by visually identifying the cartilaginous rings and the pars membranacea. Advance the endoscope until it rests above the carina. Try not to touch the sensitive mucosa with the tip of the endoscope to avoid swelling and bleeding.</li>
	<li>While maintaining the position of the endoscope, advance the endotracheal tube until it becomes visible in the camera image. 
	NOTE: If the endotracheal tube cannot be advanced through the glottic plane, there is a possibility that it has become caught on the arytenoid cartilage. In this case, the endotracheal tube must be withdrawn 1 cm and rotated by 90&#176; before gently advancing again. If necessary, this maneuver can be repeated. Similar calibers of flexible intubation endoscope and endotracheal tube can minimize the risk of this issue occurring. If the endotracheal tube cannot be advanced despite this maneuver, it is likely that the subglottic narrowness-the narrowest part of the porcine larynx-cannot be passed. In this case, a smaller endotracheal tube size needs to be selected. Regular commercially available endotracheal tubes in sizes 6.5 cm or 7.0 cm ID should be able to pass the glottis as long as no anatomic abnormalities are present. Endotracheal tube size requirements vary depending on the piglet size and breed.</li>
	<li>Withdraw the flexible intubation endoscope while maintaining the position of the endotracheal tube.</li>
	<li>Using a 10 mL syringe, inflate the cuff with 10 mL of air. Control the cuff pressure with a cuff manager (target value: 30 cmH2O, see Table of Materials).</li>
	<li>Confirm the correct placement of the endotracheal tube and adequate ventilation by periodic and regular exhalation of carbon dioxide via capnography24 and double-sided ventilation via auscultation15.</li>
	<li>Start mechanical ventilation after connecting the tube with a ventilator (PEEP = 5 cmH2O, respiratory rate = variable to achieve an end-tidal CO2 of &#60;6 kPa, usually 30-50 min&#8722;1, FiO2 = 0.4, I:E (inspiration to expiration ratio) = 1:2, tidal volume = 6-8 mL/kg).</li>
	<li>Expand the monitoring (e.g., the establishment of an intra-arterial blood pressure measurement, the installation of a central venous or pulmonary arterial catheter27) or continue with the intervention. 
	NOTE: Depending on the question of the further experiments, define limit values for the vital parameters and intervention options and establish the monitoring accordingly in the study protocol.</li>
</ol>

The flexible intubation endoscope and its accessories have been provided unconditionally by the manufacturer for research purposes only. The authors declare no further financial or other conflicts of interest.

In previous studies, our research group has already described specific details regarding the translational benefits of the porcine model2,27,32,33. Generally, reducing the stress level of the animal and unnecessary pain should be an integral part of any study protocol and is paramount for generating reliably reproducible data. Therefore, awake endoscopically guided intubation of the pig with an...

An erratum was issued for:&#160;<a href="https://www.jove.com/t/63955">Endotracheal Intubation Using a Flexible Intubation Endoscope As a Standardized Model for Safe Airway Management in Swine</a>. The Protocol, Representative Results, and Discussion sections were updated.
In the Protocol, step 1.5 was updated from:
Disinfect the skin with a disinfectant (alcoholic) before inserting a peripheral vein cannula (22 G) into an ear vein. Spray the area, wipe once, then spray again, and allow the disinfectant to dry.
to:
Disinfect the skin with a disinfectant (alcoholic) before inserting a peripheral vein cannula (22 G) into an ear vein. Spray the area, wipe once, then spray again, and allow the disinfectant to dry. Secure the ear cannula with a band-aid (See Table of Materials).
In the Protocol, step 3.7 was updated from:
While maintaining the position of the endoscope, advance the endotracheal tube until it becomes visible in the camera image. 
NOTE: If the endotracheal tube cannot be advanced through the glottic plane, there is a possibility that it has become caught on the arytenoid cartilage. In this case, the endotracheal tube must be withdrawn 1 cm and rotated by 90&#176; before gently advancing again. If necessary, this maneuver can be repeated. Similar calibers of flexible intubation endoscope and endotracheal tube can minimize the risk of this issue occurring. If the endotracheal tube cannot be advanced despite this maneuver, it is likely that the subglottic narrowness-the narrowest part of the porcine larynx-cannot be passed. In this case, a smaller endotracheal tube size needs to be selected. Regular commercially available endotracheal tubes in sizes 6.5 cm or 7.0 cm ID should be able to pass the glottis as long as no anatomic abnormalities are present.
to:
While maintaining the position of the endoscope, advance the endotracheal tube until it becomes visible in the camera image. 
NOTE: If the endotracheal tube cannot be advanced through the glottic plane, there is a possibility that it has become caught on the arytenoid cartilage. In this case, the endotracheal tube must be withdrawn 1 cm and rotated by 90&#176; before gently advancing again. If necessary, this maneuver can be repeated. Similar calibers of flexible intubation endoscope and endotracheal tube can minimize the risk of this issue occurring. If the endotracheal tube cannot be advanced despite this maneuver, it is likely that the subglottic narrowness-the narrowest part of the porcine larynx-cannot be passed. In this case, a smaller endotracheal tube size needs to be selected. Regular commercially available endotracheal tubes in sizes 6.5 cm or 7.0 cm ID should be able to pass the glottis as long as no anatomic abnormalities are present. Endotracheal tube size requirements vary depending on the piglet size and breed.
In the Representative Results, the sixth paragraph was updated from:
Statistical analyses were performed using commercially available software (see Table of Materials). Normal distribution was examined using the Kolmogorov-Smirnoff test28. If a normal distribution was determined, group differences were analyzed using t-tests of independent samples29 or the Mann-Whitney U test30 for the non-parametric version. Data are presented as mean (&#177; standard deviation). Correlations of ordinal-scale data were examined using Spearman&#39;s correlation coefficient31. A significance level of p &#60; 0.05 was assumed.
to:
Statistical analyses were performed using commercially available software (see Table of Materials). Normal distribution was examined using the Kolmogorov-Smirnoff test28. If a normal distribution was determined, group differences were analyzed using t-tests of independent samples29 or the Mann-Whitney U test30 for the non-parametric version. Data are presented as mean (&#177; standard deviation). Correlations of ordinal-scale data were examined using Spearman&#39;s correlation coefficient31. A significance level of p &#60; 0.05 was assumed. All tests were performed with exploratory intention; therefore p-values are descriptive. Nevertheless, p &#60; 0.05 was accepted as indicative of statistical significance.
In the Representative Results, the legend for figure 1 was updated from:
Figure 1: Number of intubation attempts in group comparison. For the group that was intubated using a flexible intubation endoscope, every intubation attempt was successful; in the group that was conventionally intubated, it took an average of 1.4 attempts before the endotracheal tube could be placed correctly. Error bars show the standard deviation. <a href="https://www.jove.com/files/ftp_upload/63955/63955fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
to:
Figure 1: Number of intubation attempts in group comparison. For the group that was intubated using a flexible intubation endoscope, every intubation attempt was successful; in the group that was conventionally intubated, it took an average of 1.4 attempts before the endotracheal tube could be placed correctly. Error bars show the standard deviation. n = 5 (for each group).&#160;<a href="https://www.jove.com/files/ftp_upload/63955/63955fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
In the Representative Results, figure 2 was updated from:
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/63955/63955fig02.jpg" /> 
Figure 2: Time until CO2 detection in group comparison. For the group that was intubated using a flexible intubation endoscope, it took significantly longer until end-tidal CO2 could be detected, depicted as mean and standard deviation. <a href="https://www.jove.com/files/ftp_upload/63955/63955fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
to:
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/63955/63955fig2v2.jpg" /> 
Figure 2: Time until CO2 detection in group comparison. For the group that was intubated using a flexible intubation endoscope, it took significantly longer until end-tidal CO2 could be detected, depicted as mean and standard deviation. n = 5 (for each group).&#160;<a href="https://www.jove.com/files/ftp_upload/63955/63955fig2v2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
In the Discussion, the fifth paragraph was updated from:
The increased duration had no clinical significance in this cohort. At no time was the termination criterion-a saturation of less than 93%-reached. This is shown in the results because a procedure change was unnecessary at any time. Prior adequate mask ventilation is a critical step to allow sufficient time for fiberoptic endotracheal tube placement to avoid rapid desaturation34. These results are consistent with previous studies comparing conventional intubation and endoscopically assisted intubations with inexperienced providers35.
to:
The increased duration had no clinical significance in this cohort. At no time was the termination criterion-a saturation of less than 93%-reached. This is shown in the results because a procedure change was unnecessary at any time. Prior adequate mask ventilation is a critical step to allow sufficient time for fiberoptic endotracheal tube placement to avoid rapid desaturation34. These results are consistent with previous studies comparing conventional intubation and endoscopically assisted intubations with inexperienced providers35. We attribute the prolonged duration of fiberoptic intubation to the fact that one must first reorient again after insertion, whereas with conventional intubation, one retains a view of the glottis. It is also important to avoid contact with the mucosa with the flexible intubation endoscope during advancement. This requires occasional corrective maneuvers. Last but not least, after successful placement, retraction of the relatively long endoscope is required, which increases the time to CO2 detection slightly.

An erratum was issued for:&#160;<a href="https://www.jove.com/t/63955">Endotracheal Intubation Using a Flexible Intubation Endoscope As a Standardized Model for Safe Airway Management in Swine</a>. The Protocol, Representative Results, and Discussion sections were updated.

Erratum: Endotracheal Intubation Using a Flexible Intubation Endoscope As a Standardized Model for Safe Airway Management in Swine

Endotracheal intubation is often a basic requirement for translational research in porcine models for various interventions that require a secured airway or high ventilation pressures (such as ventilation during cardiopulmonary resuscitation1 or acute respiratory distress syndrome2) or require that cerebral blood flow is not compromised through internal compression by supraglottic airway devices3, which are occasionally propagated as alternatives in the context of an anticipated difficult airway in pigs4,5.
While the lung physiology of pigs shows similar features to that of humans6, securing the airway is sometimes significantly more difficult7 due to specific differences in the porcine orotracheal anatomy. The snout of a pig has a narrow opening with a very large tongue, the larynx is extremely mobile, and the epiglottis is relatively large, with a free end that extends to the soft palate. Caudally, the larynx forms an obtuse angle with the trachea. The arytenoid cartilages are large8. The narrowest part of the airway is at the subglottic level9, comparable to the airway anatomy of children10. Since the larynx in pigs is very mobile, there is a risk that the end of the endotracheal tube will pass through the vocal cords but the larynx will only be displaced caudally by up to several centimeters, which may be mistaken for a correct intubation8,11. Additionally, esophageal intubation is a common risk when dealing with porcine airway management12.
The rates of difficult or impossible endotracheal intubations with a corresponding negative impact on the experiment or early mortality have not been systematically recorded, but several case reports have been published13,14. In humans, there is the possibility of using a flexible intubation endoscope in the context of an unexpectedly difficult conventional intubation15. Various false intubations often precede this measure. These repeated intubation attempts are associated with adverse events in humans16,17, especially airway complications18. Such events are deleterious in test animals since, in the simplest case, they represent a confounder variable in the experiment; in the worst case, they can lead to the unnecessary loss of the animal.
The present study has developed a model based on the guidelines for expected difficult airway management in humans15,19,20,21,22,23,24. Previously, a similar technique has been described for learning fiberoptic intubation in human studies25,26. The protocol presented in this report aims to provide a standardized and easy-to-adapt intubation model that also allows non-airway specialists to perform successful and safe endotracheal intubation in pigs.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Ambu aScope Regular</td>
			<td>Ambu GmbH, Medizinprodukte, Bad Nauheim, Germany</td>
			<td></td>
			<td>Disposable fiber optic outer diameter 5 mm</td>
		</tr>
		<tr>
			<td>Ambu aView Monitor</td>
			<td>Ambu GmbH, Medizinprodukte, Bad Nauheim, Germany</td>
			<td></td>
			<td>monitor</td>
		</tr>
		<tr>
			<td>Atracurium Hikma 50 mg/5mL</td>
			<td>Hikma Pharma GmbH, Martinsried</td>
			<td></td>
			<td>atracurium</td>
		</tr>
		<tr>
			<td>Azaperone (Stresnil) 40mg/mL</td>
			<td>Lilly Deutschland GmbH, Bad Homburg, Germany</td>
			<td></td>
			<td>azaperone</td>
		</tr>
		<tr>
			<td>BD Discardit II Spritze 2, 5, 10, 20 mL</td>
			<td>Becton Dickinson S.A. Carretera, Mequinenza Fraga, Spain</td>
			<td></td>
			<td>syringe</td>
		</tr>
		<tr>
			<td>BD Luer Connecta</td>
			<td>Becton Dickinson Infusion Therapy, AB Helsingborg, Schweden</td>
			<td></td>
			<td>3-way-stopcock</td>
		</tr>
		<tr>
			<td>BD Microlance 3 20 G</td>
			<td>Becton Dickinson S.A. Carretera, Mequinenza Fraga, Spain</td>
			<td></td>
			<td>cannula</td>
		</tr>
		<tr>
			<td>Curafix i.v. classics</td>
			<td>Lohmann &#38; Rauscher International GmbH &#38; Co. KG, Rengsdorf, Germany</td>
			<td></td>
			<td>Cannula retention dressing</td>
		</tr>
		<tr>
			<td>Engstr&#246;m Carestation</td>
			<td>GE Heathcare, Madison USA</td>
			<td></td>
			<td>ventilator</td>
		</tr>
		<tr>
			<td>Fentanyl-Janssen 0.05 mg/mL</td>
			<td>Janssen-Cilag GmbH, Neuss</td>
			<td></td>
			<td>fentanyl</td>
		</tr>
		<tr>
			<td>F&#252;hrungsstab, Durchmesser 4.3</td>
			<td>R&#252;sch</td>
			<td></td>
			<td>endotracheal tube introducer</td>
		</tr>
		<tr>
			<td>IBM SPSS Statistics for Windows, Version 20</td>
			<td>IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp.)</td>
			<td></td>
			<td>Statistical software</td>
		</tr>
		<tr>
			<td>Incetomat-line 150 cm</td>
			<td>Fresenius, Kabi Deutschland, GmbH</td>
			<td></td>
			<td>perfusor line</td>
		</tr>
		<tr>
			<td>Intrafix Primeline</td>
			<td>B. Braun Melsungen AG, Melsungen, Germany</td>
			<td></td>
			<td>Infusion line</td>
		</tr>
		<tr>
			<td>JOZA Einmal Nitril Untersuchungshandschuhe</td>
			<td>JOZA, M&#252;nchen, Germany</td>
			<td></td>
			<td>disposable gloves</td>
		</tr>
		<tr>
			<td>Laryngoscope, 45.48.50, KL 2000</td>
			<td>Medicon</td>
			<td></td>
			<td>Laryngoscope handle</td>
		</tr>
		<tr>
			<td>Littmann Classic III Stethoscope</td>
			<td>3M Deutschland GmbH, Neuss, Germany</td>
			<td></td>
			<td>stethoscope</td>
		</tr>
		<tr>
			<td>Luer Lock</td>
			<td>B.Braun Melsungen AG, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Maimed Vlieskompresse</td>
			<td>Maimed GmbH, Neuenkirchen, Germany</td>
			<td></td>
			<td>Fleece compress to fix the tongue</td>
		</tr>
		<tr>
			<td>Masimo LNCS Adtx SpO2 sensor</td>
			<td>Masimo Corporation Irvine, Ca 92618 USA</td>
			<td></td>
			<td>saturation clip for the tail</td>
		</tr>
		<tr>
			<td>Masimo LNCS TC-I SpO2 ear clip sensor</td>
			<td>Masimo Corporation Irvine, Ca 92618 USA</td>
			<td></td>
			<td>Saturation clip for the ear</td>
		</tr>
		<tr>
			<td>Masimo Radical 7</td>
			<td>Masimo Corporation Irvine, Ca 92618 USA</td>
			<td></td>
			<td>periphereal oxygen saturation</td>
		</tr>
		<tr>
			<td>Midazolam 15 mg/3 mL</td>
			<td>Hameln Pharma GmbH, Hameln, Germany</td>
			<td></td>
			<td>midazolam</td>
		</tr>
		<tr>
			<td>Midmark Canine Mask Small Plastic with Diaphragm FRSCM-0005</td>
			<td>Midmark Corp., Dayton, Ohio, USA</td>
			<td></td>
			<td>dog ventilation mask</td>
		</tr>
		<tr>
			<td>Octeniderm farblos</td>
			<td>Sch&#252;lke &#38; Mayr GmbH, Nordenstedt, Germany</td>
			<td></td>
			<td>Alcoholic disinfectant</td>
		</tr>
		<tr>
			<td>Original Perfusor syringe 50 mL</td>
			<td>B.Braun Melsungen AG, Germany</td>
			<td></td>
			<td>perfusor syringe</td>
		</tr>
		<tr>
			<td>Perfusor FM Braun</td>
			<td>B.Braun Melsungen AG, Germany</td>
			<td></td>
			<td>syringe pump</td>
		</tr>
		<tr>
			<td>Propofol 2% 20 mg/mL (50 mL flasks)</td>
			<td>Fresenius, Kabi Deutschland, GmbH</td>
			<td></td>
			<td>propofol</td>
		</tr>
		<tr>
			<td>R&#220;SCH F&#252;hrungsstab f&#252;r Endotrachealtubus (ID 5.6 mm)</td>
			<td>Teleflex Medical Sdn. Bhd, Malaysia</td>
			<td></td>
			<td>PVC coated tube guiding wire</td>
		</tr>
		<tr>
			<td>R&#252;schelit Super Safety Clear &#62;ID 6/6.5 /7.0 mm</td>
			<td>Teleflex Medical Sdn. Bhd, Malaysia</td>
			<td></td>
			<td>endotracheal tube</td>
		</tr>
		<tr>
			<td>Stainless Macintosh Gr&#246;&#223;e 4</td>
			<td>Welch Allyn69604</td>
			<td></td>
			<td>blade for laryngoscope</td>
		</tr>
		<tr>
			<td>Sterofundin</td>
			<td>B.Braun Melsungen AG, Melsungen, Germany</td>
			<td></td>
			<td>Balanced electrolyte solution</td>
		</tr>
		<tr>
			<td>Ultrastop Antibeschlagmittel bottle with dropper 25 mL</td>
			<td>Sigmapharm Arzneimittel GmbH, Wien, Austria</td>
			<td></td>
			<td>Antifog agent</td>
		</tr>
		<tr>
			<td>Vasofix Safety 22 G-16 G</td>
			<td>B.Braun Melsungen AG, Germany</td>
			<td></td>
			<td>venous catheter</td>
		</tr>
		<tr>
			<td>VBM Cuff Manometer</td>
			<td>VBM Medizintechnik GmbH, Sulz a.N., Germany</td>
			<td></td>
			<td>cuff pressure gauge</td>
		</tr>
		<tr>
			<td>Zelette</td>
			<td>Lohmann &#38; Rauscher International GmbH &#38; Co. KG, Rengsdorf, Germany</td>
			<td></td>
			<td>Tissue swab</td>
		</tr>
	</tbody>
</table>

endotracheal intubation using a flexible intubation endoscope as a standardized model for safe airway management in swine

Endotracheal intubation is often a basic requirement for translational research in porcine models for various interventions that require a secured airway or high ventilation pressures. Endotracheal intubation is a challenging skill,&#160;requiring a minimum number of successful endotracheal intubations to achieve a high success rate under optimal conditions, which is often unachievable for non-anaesthesiology researchers. Due to the specific porcine airway anatomy, a difficult airway can usually be assumed. The impossibility of establishing a secure airway can result in injury, adverse events, or death of the laboratory animal. Using a prospective, randomized, controlled evaluation approach, it has been shown that fiberoptic-assisted endotracheal intubation takes longer but has a higher first-pass success rate than conventional intubation without causing clinically relevant drops in oxygen saturation. This model presents a standardized regimen for endoscopically guided endotracheal intubation, providing a secured airway, especially for researchers who are inexperienced in the technique of endotracheal intubation via direct laryngoscopy. This procedure is expected to minimize animal suffering and unnecessary animal losses.

Endotracheal intubation was performed on 10 male pigs (age 12-16 weeks, weight 30 kg &#177; 3 kg) in a prospective, randomized, controlled study setting. The pigs were randomized into two groups: one was conventionally laryngoscopically intubated (CI group), and the other group was intubated assisted via a flexible intubation endoscope as described in the protocol (FIE group). The group assignment was done by pulling sealed envelopes. The investigator was assigned randomly on a daily basis.
<p class="jove_co...

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Endotracheal Intubation Using a Flexible Intubation Endoscope as a Standardized Model for Safe Airway Management in Swine

The use of pigs in research has increased in recent years. Nevertheless, pigs are characterized by difficult airway anatomy. By demonstrating how to perform endoscopically guided endotracheal intubation, the present protocol aims to further increase laboratory animals' safety to avoid animal suffering and unnecessary death.

Endotracheal intubation is often a basic requirement for translational research in porcine models for various interventions that require a secured airway ...

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2.9K Views.  University Medical Center of the Johannes Gutenberg-University. The use of pigs in research has increased in recent years. Nevertheless, pigs are characterized by difficult airway anatomy. By demonstrating how to perform endoscopically guided endotracheal intubation, the present protocol aims to further increase laboratory animals' safety to avoid animal suffering and unnecessary death.

Video: Endotracheal Intubation Using a Flexible Intubation Endoscope as a Standardized Model for Safe Airway Management in Swine

A Novel Rescue Technique for Difficult Intubation and Difficult Ventilation

We describe a novel non surgical technique to maintain oxygenation and ventilation in a case of difficult intubation and difficult ventilation, which works especially well with poor mask fit.
Can not intubate, can not ventilate" (CICV) is a potentially life threatening situation. In this video we present a simulation of the technique we used in a case of CICV where oxygenation and ventilation were maintained by inserting an endotracheal tube (ETT) nasally down to the level of the naso-pharynx while sealing the mouth and nares for successful positive pressure ventilation.
A 13 year old patient was taken to the operating room for incision and drainage of a neck abcess and direct laryngobronchoscopy. After preoxygenation, anesthesia was induced intravenously. Mask ventilation was found to be extremely difficult because of the swelling of the soft tissue. The face mask could not fit properly on the face due to significant facial swelling as well. A direct laryngoscopy was attempted with no visualization of the larynx. Oxygen saturation was difficult to maintain, with saturations falling to 80%. In order to oxygenate and ventilate the patient, an endotracheal tube was then inserted nasally after nasal spray with nasal decongestant and lubricant. The tube was pushed gently and blindly into the hypopharynx. The mouth and nose of the patient were sealed by hand and positive pressure ventilation was possible with 100% O2 with good oxygen saturation during that period of time. Once the patient was stable and well sedated, a rigid bronchoscope was introduced by the otolaryngologist showing extensive subglottic and epiglottic edema, and a mass effect from the abscess, contributing to the airway compromise. The airway was secured with an ETT tube by the otolaryngologist.This video will show a simulation of the technique on a patient undergoing general anesthesia for dental restorations.

We describe a technique to maintain oxygenation and ventilation using an endotracheal tube inserted nasally to the level of the naso-pharynx while sealing the mouth and nares for successful positive pressure ventilation.

We describe a novel non surgical technique to maintain oxygenation and ventilation in a case of difficult intubation and difficult ventilation, which ...

Guidelines for Elective Pediatric Fiberoptic Intubation

Fiberoptic intubation in pediatric patients is often required especially in difficult airways of syndromic patients i.e. Pierre Robin Syndrome. Small babies will desaturate very quickly if ventilation is interrupted mainly to high metabolic rate. We describe guidelines to perform a safe fiberoptic intubation while maintaining spontaneous breathing throughout the procedure. Steps requiring the use of propofol pump, fentanyl, glycopyrrolate, red rubber catheter, metal insuflation hook, afrin, lubricant and lidocaine spray are shown.

We describe guidelines to perform a safe and efficient elective fiberoptic intubation in pediatric patients while maintaining spontaneous ventilation.

Fiberoptic intubation in pediatric patients is often required especially in difficult airways of syndromic patients i.e. Pierre Robin Syndrome. Small ...

Endotracheal Intubation in Mice via Direct Laryngoscopy Using an Otoscope

Mice, both wildtype and transgenic, are the principal mammalian model in biomedical research currently. Intubation and mechanical ventilation are necessary for whole animal experiments that require surgery under deep anesthesia or measurements of lung function. Tracheostomy has been the standard for intubating the airway in these mice to allow mechanical ventilation. Orotracheal intubation has been reported but has not been successfully used in many studies because of the substantial technical difficulty or a requirement for highly specialized and expensive equipment. Here we report a technique of direct laryngoscopy using an otoscope fitted with a 2.0 mm speculum and using a 20 G&#160;intravenous catheter as an endotracheal tube. We have used this technique extensively and reliably to intubate and conduct accurate assessments of lung function in mice. This technique has proven safe, with essentially no animal loss in experienced hands. Moreover, this technique can be used for repeated studies of mice in chronic models.

Endotracheal Intubation in Mice via Direct Laryngoscopy Using an Otoscope

We have developed a simple, reliable, and relatively inexpensive method for endotracheal intubation in mice via direct laryngoscopy using an otoscope with a 2.0 mm speculum. This technique is atraumatic and can be used for repeated measurements in chronic experiments. We find it superior to tracheostomy or previously reported nonsurgical techniques.

Mice, both wildtype and transgenic, are the principal mammalian model in biomedical research currently. Intubation and mechanical ventilation are ...

A Simple Method of Mouse Lung Intubation

A simple procedure to intubate mice for pulmonary function measurements would have several advantages in longitudinal studies with limited numbers or expensive animal. One of the reasons that this is not done more routinely is that it is relatively difficult, despite there being several published studies that describe ways to achieve it. In this paper we demonstrate a procedure that eliminates one of the major hurdles associated with this intubation, that of visualizing the trachea during the entire time of intubation. The approach uses a 0.5 mm fiberoptic light source that serves as an introducer to direct the intubation cannula into the mouse trachea. We show that it is possible to use this procedure to measure lung mechanics in individual mice over a time course of at least several weeks. The technique can be set up with relatively little expense and expertise, and it can be routinely accomplished with relatively little training. This should make it possible for any laboratory to routinely carry out this intubation, thereby allowing longitudinal studies in individual mice, thereby minimizing the number of mice needed and increasing the statistical power by using each mouse as its own control.

This paper describes a striaghforward and efficient method of intubating mice for pulmonary function measurements or pulmonary instillation, that allows the mice to recover and be studied at later times. The procedure involves an inexpensive fiberoptic light source that directly illuminates the trachea.

A  simple procedure to intubate mice for pulmonary function measurements would  have several advantages in longitudinal studies with limited numbers or  ...

Intubation-mediated Intratracheal (IMIT) Instillation: A Noninvasive, Lung-specific Delivery System

Respiratory disease studies typically involve the use of murine models as surrogate systems. However, there are significant physiologic differences between the murine and human respiratory systems, especially in their upper respiratory tracts (URT). In some models, these differences in the murine nasal cavity can have a significant impact on disease progression and presentation in the lower respiratory tract (LRT) when using intranasal instillation techniques, potentially limiting the usefulness of the mouse model to study these diseases. For these reasons, it would be advantageous to develop a technique to instill bacteria directly into the mouse lungs in order to study LRT disease in the absence of involvement of the URT. We have termed this lung specific delivery technique intubation-mediated intratracheal (IMIT) instillation. This noninvasive technique minimizes the potential for instillation into the bloodstream, which can occur during more invasive traditional surgical intratracheal infection approaches, and limits the possibility of incidental digestive tract delivery. IMIT is a two-step process in which mice are first intubated, with an intermediate step to ensure correct catheter placement into the trachea, followed by insertion of a blunt needle into the catheter to mediate direct delivery of bacteria into the lung. This approach facilitates a &#62;98% efficacy of delivery into the lungs with excellent distribution of reagent throughout the lung. Thus, IMIT represents a novel approach to study LRT disease and therapeutic delivery directly into the lung, improving upon the ability to use mice as surrogates to study human respiratory disease. Furthermore, the accuracy and reproducibility of this delivery system also makes it amenable to Good Laboratory Practice Standards (GLPS), as well as delivery of a wide range of reagents which require high efficiency delivery to the lung.

Intubation-mediated Intratracheal IMIT Instillation: A Noninvasive, Lung-specific Delivery System

Intubation-mediated intratracheal (IMIT) instillation of reagents is an excellent, noninvasive method for studying respiratory disease, as well as a method for instilling therapeutic reagents directly into the lung. It is a rapid and highly reproducible method which is suitable for preclinical testing.

Respiratory disease studies typically involve the use of murine models as surrogate systems. However, there are significant physiologic differences ...

Topical Airway Anesthesia for Awake-endoscopic Intubation Using the Spray-as-you-go Technique with High Oxygen Flow

A patient&#39;s willingness to cooperate is an absolute precondition for successful awake intubation of the trachea. Whilst drug-sedation of patients can jeopardize their spontaneous breathing, topical anesthesia of the airway is a popular technique. The spray-as-you-go technique represents one of the simplest opportunities to anesthetize the airway mucosa. The application of local anesthetic through the working channel of the flexible endoscope is a widespread practice for anesthetists as well as pulmonologists. There is neither need for additional devices nor special training as a pre-requisite to perform this technique. However, a known clinical problem is the coughing and gagging reflex that may occur when the liquid anesthetic strikes the airway mucosa and other sensitive structures like the vocal cords. This can be avoided by the use of oxygen applied through the working channel with the aim of fogging the local anesthetic into finer particles. Furthermore, the oxygen flow provides a higher oxygen supply and contributes to a better view, dispersing mucus secretions and blood away from the lens. Using an atomizer with a high oxygen flow of 10 L/min we maximized these benefits, caused less coughing and had more satisfied and therefore cooperative patients. Possible, but very rare complications of using oxygen flow including gastric insufflation, organ rupture or barotrauma did not arise. We attribute the complication-free use of high oxygen flow to the design of the set, which permits flow and pressure release.

The topical anesthetic lidocaine was atomized using a high oxygen flow through the working channel of a flexible intubating endoscope to achieve topical airway anesthesia for awake endotracheal intubation. We prefer this modified spray-as-you-go technique for endoscopic intubation to classical bolus application because of higher patient satisfaction and better compliance.

A patient&#39;s willingness to cooperate is an absolute precondition for successful awake intubation of the trachea. Whilst drug-sedation of patients can ...

Tachycardia-Induced Cardiomyopathy As a Chronic Heart Failure Model in Swine

A stable and reliable model of chronic heart failure is required for many experiments to understand hemodynamics or to test effects of new treatment methods. Here, we present such a model by tachycardia-induced cardiomyopathy, which can be produced by rapid cardiac pacing in swine.
A single pacing lead is introduced transvenously into fully anaesthetized healthy swine, to the apex of the right ventricle, and fixated. Its other end is then tunneled dorsally to the paravertebral region. There, it is connected to an in-house modified heart pacemaker unit that is then implanted in a subcutaneous pocket. 
After 4 - 8 weeks of rapid ventricular pacing at rates of 200 - 240 beats/min, physical examination revealed signs of severe heart failure - tachypnea, spontaneous sinus tachycardia, and fatigue. Echocardiography and X-ray showed dilation of all heart chambers, effusions, and severe systolic dysfunction. These findings correspond well to decompensated dilated cardiomyopathy and are also preserved after the cessation of pacing.
This model of tachycardia-induced cardiomyopathy can be used for studying the pathophysiology of progressive chronic heart failure, especially hemodynamic changes caused by new treatment modalities like mechanical circulatory supports. This methodology is easy to perform and the results are robust and reproducible.

Here, we present a protocol to produce tachycardia-induced cardiomyopathy in swine. This model represents a potent way to study the hemodynamics of progressive chronic heart failure and the effects of applied treatment.

A stable and reliable model of chronic heart failure is required for many experiments to understand hemodynamics or to test effects of new treatment ...

Repeated Orotracheal Intubation in Mice

The literature describes several methods for mouse intubation that either require visualization of the glottis through the oral cavity or incision in the ventral neck for direct confirmation of cannula placement in the trachea. The relative difficulty or the tissue trauma induced to the subject by such procedures can be an impediment to an investigator&#8217;s ability to perform longitudinal studies. This article illustrates a technique in which physical manipulation of the mouse following the use of a depilatory to remove hair from the ventral neck permits transcutaneous visualization of the trachea for orotracheal intubation regardless of degree of skin pigmentation. This method is innocuous to the subject and easily achieved with a limited understanding of murine anatomy. This refined approach facilitates repeated intubation, which may be necessary for monitoring progression of disease or instillation of treatments. Using this method may result in a reduction of the number of animals and technical skill required to measure lung function in mouse models of respiratory disease.

The goal of this article is to describe a refined method of intubation of the laboratory mouse. The method is noninvasive and, therefore, ideal for studies that require serial monitoring of respiratory function and/or instillation of treatments into the lung.

The literature describes several methods for mouse intubation that either require visualization of the glottis through the oral cavity or incision in the ...

Blind Endotracheal Intubation in Neonatal Rabbits

The newborn rabbit is a useful animal model for various pathologies and procedures. Airway management of the rabbit is complex due to its anatomical characteristics, which is further complicated in the case of the newborn. Of the different methods of advanced airway management, endotracheal intubation is less aggressive than tracheostomy, and is more feasible than supraglottic management given the lack of supraglottic devices of such a small size. As direct glottis visualization is very difficult in animals this size, this blind intubation model is presented as an effective alternative, especially for experiments requiring prolonged anesthesia. Using this method, we performed blind intubations with a 90% success rate.

We describe a technique of endotracheal intubation in newborn rabbits after esophageal catheterization with a gastric tube.

The newborn rabbit is a useful animal model for various pathologies and procedures. Airway management of the rabbit is complex due to its anatomical ...

Image Acquisition using Portable Sonography for Emergency Airway Management

With its increasing popularity and accessibility, portable ultrasonography has been rapidly adapted not only to improve the perioperative care of patients, but also to address the potential benefits of employing ultrasound in airway management. The benefits of point of care ultrasound (POCUS) include its portability, the speed at which it can be utilized, and its lack of invasiveness or exposure of the patient to radiation of other imaging modalities.
Two primary indications for airway POCUS include confirmation of endotracheal intubation and identification of the cricothyroid membrane in the event a surgical airway is required. In this article, the technique of using ultrasound to confirm endotracheal intubation and the relevant anatomy is described, along with the associated ultrasonographic images. In addition, identification of the anatomy of the cricothyroid membrane and the ultrasonographic acquisition of appropriate images to perform this procedure are reviewed.
Future advances include utilizing airway POCUS to identify patient characteristics that might indicate difficult airway management. Traditional bedside clinical exams have, at best, fair predictive values. The addition of ultrasonographic airway assessment has the potential to improve this predictive accuracy. This article describes the use of POCUS for airway management, and initial evidence suggests that this has improved the diagnostic accuracy of predicting a difficult airway. Given that one of the limitations of airway POCUS is that it requires a skilled sonographer, and image analysis can be operator dependent, this paper will provide recommendations to standardize the technical aspects of airway ultrasonography and promote further research utilizing sonography in airway management. The goal of this protocol is to educate researchers and medical health professionals and to advance the research in the field of airway POCUS.

Point of care ultrasound (POCUS) is increasingly being utilized in airway management. Presented here are some clinical utilities of POCUS, including differentiating endotracheal and esophageal intubation, identification of the cricothyroid membrane in the event a surgical airway is required, and measuring anterior neck soft tissue to predict difficult airway management.