This work was supported by grants from the Instituto de Salud Carlos III [PFIS2017-0224], &#34;Beca Ruza&#34; from the Sociedad Espa&#241;ola de Cuidados Intensivos Pedi&#225;tricos and the Vanderbilt Medical Scholars Program.
The sponsors were not involved in the collection, analysis, or interpretation of the data.
We would like to thank Isabel Salas for the help provided within the animal laboratory and the Mr. Carles F&#225;brega and Ms. Gemma Fernandez-Asensio from the Audio-Visual Techincal Team from Sant Joan de D&#233;u Hospital for their technical support with the video recording and production.

The intubation procedure outlined below was approved by the Barcelona University Institutional Animal Care and Use Committee (CEEA 180/19)
1. Experimental preparation
<ol>
	<li>Obtain the following materials: 2 mm diameter polyvinyl chloride (PVC) endotracheal tube, 6 French (Fr) polyurethane feeding tube, flat and wide tip dissection forceps and sterile lubricant (Figure 1).</li>
	<li>During the intubation and surgery processes, maintain sterile conditions.</li...

<ol>
	<li>Gilroy, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endotracheal+intubation+of+rabbits+and+rodents.">Endotracheal intubation of rabbits and rodents.</a> Journal of the American Veterinary Medical Association. 179 (11), 1295 (1981).</li><li>Graham, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Common+procedures+in+rabbits.">Common procedures in rabbits.</a> The Veterinary Clinics of North America. Exotic Animal Practice. 9 (2), 367-388 (2006).</li><li>Fick, T. E., Schalm, S. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+technique+for+endotracheal+intubation+in+rabbits.">A simple technique for endotracheal intubation in rabbits.</a> Laboratory Animals. 21 (3), 265-266 (1987).</li><li>Conlon, K. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atraumatic+endotracheal+intubation+in+small+rabbits.">Atraumatic endotracheal intubation in small rabbits.</a> Laboratory Animal Science. 40 (2), 221-222 (1990).</li><li>Johnson, D. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscopic+intubation+of+exotic+companion+mammals.">Endoscopic intubation of exotic companion mammals.</a> The Veterinary Clinics of North America. Exotic Animal Practice. 13 (2), 273-289 (2010).</li><li>Falc&#227;o, S. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Technique+of+blind+tracheal+intubation+in+rabbits+(Oryctolagus+cuniculi)+supported+by+previous+maneuver+of+esophageal+cannulization.">Technique of blind tracheal intubation in rabbits (Oryctolagus cuniculi) supported by previous maneuver of esophageal cannulization.</a> Acta Cirurgica Brasileira. 26 (5), 352-356 (2011).</li><li>Miura, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endotracheal+intubation+in+rabbits.">Endotracheal intubation in rabbits.</a> The Japanese Journal of Veterinary Anesthesiology. 19 (1), 25-29 (2012).</li><li>Thompson, K. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endotracheal+Intubation+of+Rabbits+Using+a+Polypropylene+Guide+Catheter.">Endotracheal Intubation of Rabbits Using a Polypropylene Guide Catheter.</a> Journal of Visualized Experiments. (129), (2017).</li><li>Comolli, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+endoscopic+endotracheal+intubation+and+the+v-gel+supraglottic+airway+device+for+spontaneously+ventilating+New+Zealand+white+rabbits+undergoing+ovariohysterectomy.">Comparison of endoscopic endotracheal intubation and the v-gel supraglottic airway device for spontaneously ventilating New Zealand white rabbits undergoing ovariohysterectomy.</a> Veterinary Record. , 1-8 (2020).</li><li>Hua, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+different+ventilation+strategies+on+lung+injury+in+newborn+rabbits.">Effects of different ventilation strategies on lung injury in newborn rabbits.</a> Pediatric Pulmonology. 47 (11), 1103-1112 (2012).</li><li>Kitchen, M. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+lung+inflation+and+sodium+transport+in+airway+liquid+clearance+during+lung+aeration+in+newborn+rabbits.">The role of lung inflation and sodium transport in airway liquid clearance during lung aeration in newborn rabbits.</a> Pediatric Research. 73 (4-1), 443-449 (2012).</li><li>Boon, M. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tubeless+tracheotomy+for+survival+airway+surgery+in+the+leporine+model.">Tubeless tracheotomy for survival airway surgery in the leporine model.</a> The Laryngoscope. 125 (3), 680-684 (2015).</li><li>Dion, G. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morbidity+and+mortality+associated+with+preclinical+tracheostomy+models.">Morbidity and mortality associated with preclinical tracheostomy models.</a> The Laryngoscope. 128 (2), 68-71 (2018).</li><li>Phaneuf, L. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tracheal+injury+after+endotracheal+intubation+and+anesthesia+in+rabbits.">Tracheal injury after endotracheal intubation and anesthesia in rabbits.</a> Journal of the American Association for Laboratory Animal Science. 45 (6), 67-72 (2006).</li></ol>

Rabbits are widely used in animal experimentation due to their availability, high reproduction rate with short intergenerational times, and easy handling2. In our center, we use 5-7-day old New Zealand rabbits (Oryctolagus cuniculus) as a neonatal model to study the neurologic repercussions of extracorporeal surgery on the developing brain. As a result, we utilize procedures that require deep anesthesia and must use endotracheal intubation for periods of time up to an hour.
<p class="...

The peculiar anatomy of the rabbit&#39;s respiratory system makes endotracheal intubation complicated. The oral cavity is deep and narrow with a limited range of mouth opening and a relatively large tongue, making direct visualization of the larynx difficult even with the use of a laryngoscope1,2. Furthermore, intubation of the newborn rabbit, which is 10-20 times smaller than the adult, is even more of a challenging procedure. In addition to these anatomical characteristics, rabbits are prone to laryngospasm secondary to manipulation of the airway.
Several intubation techniques have been described in the literature, such as laryngoscope tracheal intubation, blind intubation, otoscope intubation, retrograde intubation, endoscope intubation, tracheostomy and supraglottic device ventilation3,4,5,6,7,8,9. All these techniques have been carried out successfully in adult rabbits; however, there are few publications regarding advanced airway management in the newborn rabbit10. One study describes performing tracheostomies in animals of this age to assess breathing mechanics and lung volumes, though this is an aggressive and irreversible technique11. This method for endotracheal intubation has proven to be an effective and low-cost method of airway management in newborn rabbits.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>2 mm diameter Polyvinyl Chloride (PVC) endotracheal tube</td>
			<td>Vygon</td>
			<td>520.20</td>
			<td></td>
		</tr>
		<tr>
			<td>6 French polyurethane feeding tube</td>
			<td>Vygon</td>
			<td>310.06</td>
			<td></td>
		</tr>
		<tr>
			<td>Anesthesia (Ketamine and Xylazine)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Multiparameter monitor Intellivue MP5</td>
			<td>Phillips</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Plain and wide tip dissection forceps</td>
			<td>LensforVision</td>
			<td>AK005</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile lubricant (Silkospray)</td>
			<td>Rush</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ventilator Servo 900c</td>
			<td>Maquet</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

In the laboratory, this technique is carried out by medical personnel with experience in experimentation with New Zealand rabbits and expertise in pediatric airway management. The procedure has been performed by one investigator in 10 animals with a global success rate of 90%. Previously, another researcher had practiced optimizing both the position of the animal and the correct tube fixation length. None of the animals were intubated in esophagus. Only one attempt (10%) failed due to the...

Watch this Scientific Journal Video about Blind Endotracheal Intubation in Neonatal Rabbits at JoVE.com

Blind Endotracheal Intubation in Neonatal Rabbits

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 ...

Introduction.Newborn rabbit is useful as an animal model of various pathologies and procedures. Some of these procedures require some advanced airway management, and it can be challenging because of the complex airway characteristics and the little size of the animal. We present a novel technique for endotracheal intubation performed by the occlusion of the esophagus and the introduction of the tube into the airway without direct visualization.Materials.We will need a two-millimeters diameter PVC endotracheal tube, a six French polyurethane feeding tube, and plain and wide-tipped dissection forceps. Also, we can use a sterile lubricant.Anesthesia. Sedate the animal with xylazine five milligrams per kilo and ketamine 25 milligrams per kilo.Apply together intramuscularly in the vastus lateralis of the femoral quadriceps. Allow three to five minutes for the medication to reach effect. Repeat those until negative pedal reflex is achieved.Evaluate the rabbit will maintain a spontaneous breathing until intubation. Endotracheal intubation. Place the animal in dorsal recumbency with the head in hyperextension.A roll made of a sterile gauze and placed in the dorsal region of the neck may be helpful. Use plain and wide-tipped dissection forceps to open the oral cavity approximately one centimeter wide. Introduce a six French polyurethane gastric tube until the cessation of its progress.The feeding tube is moved and fix it. Introduce the two-millimeter diameter PVC endotracheal tube impregnated with the sterile lubricant until it reaches the three-centimeter mark. If there are any difficulties in advancing the tube, it should be completely removed and re-attempt until a smooth glide is achieved.The tube is also fixed.Results. The procedure has been performed in 10 animals. Their weight range was between 110 to 210 grams depending of the day of life and their nutritional status.The global success rate was 90%The only failure occurred in the smallest rabbit because of its narrow airway.Conclusion. The model of intubation of newborn rabbits we describe here doesn't require the use of specialized equipment, it's easy to master and can be performed by a single individual without the need for an assistant. All blind airway access techniques present some level of risk, but we believe this technique is an option when guided visualization is difficult, as in very little animals.

blind-endotracheal-intubation-in-neonatal-rabbits

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JoVE Journal

Medicine

5.1K 조회수.  Hospital Sant Joan de Déu, Institut de Recerca Sant Joan de Déu. 소개.신생아 토끼는 다양한 병리학 및 절차의 동물 모델로 유용합니다. 이러한 절차 중 일부는 일부 고급 기도 관리가 필요하며 복잡한 기도 특성과 동물의 작은 크기 때문에 어려울 수 있습니다. 식도의 폐색과 직접 시각화없이 기도로 튜브를 도입하여 수행되는 내트라큐레이션에 대한 새로운 기술을 제시합니다. 자료.직경 2밀리미터의 PVC 내트라세힐 튜브, 6개의 프랑...