Name: Video-Assisted Orotracheal Intubation in Rats Using a Low-Cost Smartphone-Connected Otoscope (Video) | JoVE Journal
Uploaded: 2026-07-14T14:10:00.000+00:00
Duration: 6 min 13 s
Description: Learn a low-cost video-assisted orotracheal intubation method for rats using a smartphone-connected otoscope. This protocol enables rapid, safe airway management with real-time visualization for experimental surgery.

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5 minutes

The authors thank the members of the INSERM U1096 laboratory and the staff of the Faculty of Medicine animal facility for their support and assistance in carrying out this work.

All animal procedures were approved by the Normand Ethics Committee for Animal Experimentation (CENOMEXA; project authorization no. 46008). Animals were acclimated for 9 days in the institutional animal facility prior to experimentation, with ad libitum. access to food and water.
1. Animals and anesthesia
<ol>
	<li>Use male Wistar rats (&#62;12 weeks old; 450&#8211;460 g). Record body weight, then administer xylazine (5 mg/kg, intraperitoneal) for anesthesia and buprenorphine (0.05 mg/kg, subcutaneous) for analgesia.</li>
	<li>Place animals in an inhalation chamber and maintain anesthesia for 15 min using a mixture of air&#8211;isoflurane at 2% (2 L/min) and oxygen (0.4 L/min).</li>
	<li>Confirm the depth of anesthesia by the absence of spontaneous movement and lack of withdrawal reflexes in the forelimbs, hind limbs, and tail in response to noxious stimulation.
	<ol>
		<li>If sedation is inadequate, place the animal back into the isoflurane induction chamber for a few additional minutes until an appropriate level of sedation is achieved.</li>
	</ol>
	</li>
</ol>
2. Orotracheal intubation
<ol>
	<li>Place the rat in the supine position on the intubation platform inclined at 45&#176; and maintain a ventilation mask over the airway throughout the procedure to preserve oxygenation (oxygen 0.4 L/min) and anesthesia (air 0.4 L/min and isoflurane 2%) (Figure 1A-C). Secure the animal by the upper incisors using a Velpeau band (Figure 1B). Scavenge excess isoflurane using an evacuation filter cartridge.</li>
	<li>Gently extend the tongue and introduce the video otoscope (Figure 2) into the oral cavity to displace the tongue away from the palate and towards the floor of the mouth (Figure 3A). Advance the otoscope until the soft palate is visualized (Figure 3B), then apply gentle traction to expose the vocal cords (Figure 3C).
	<ol>
		<li>If the vocal cords are not visualized, reposition the tongue by gently applying traction and displacing it toward the floor of the mouth.</li>
		<li>If esophageal intubation occurs, remove the guide and the endotracheal tube. Reposition the animal and ensure clear visualization of the vocal cords by applying gentle traction to the tongue. Ensure that the curvature of the flexible guide is oriented toward the vocal cords before reattempting intubation.</li>
		<li>If oxygen desaturation occurs (e.g., the tongue appears bluish or purple), pause the procedure and apply the nasal mask over the animal&#8217;s snout to restore oxygenation.</li>
		<li>If intubation attempts are unsuccessful (e.g., after two attempts) and desaturation occurs, place the animal back into the induction chamber and increase oxygen delivery to restore adequate oxygenation while maintaining isoflurane for an appropriate depth of anesthesia.</li>
	</ol>
	</li>
	<li>Insert the flexible guide between the vocal cords using its anterior curvature (Figure 3D).</li>
	<li>Advance the endotracheal tube carefully over the guide into the trachea until a tactile resistance corresponding to the tracheal rings is perceived (Figure 3E). 
	NOTE: In this protocol, the authors used a metallic tube with an approximate diameter of 2.8 mm, as specified in the Table of Materials.</li>
	<li>Release the rat from the Velpeau band, remove the guide, connect the endotracheal tube to the ventilator, and secure it with adhesive tape (Figure 4A).</li>
</ol>
3. Verification of tube placement and ventilation
<ol>
	<li>Before intubation, set the tidal volume to 7.5 mL/kg.</li>
	<li>Confirm the absence of selective intubation by observing bilateral thoracic expansion, a stable capnography waveform, and adequate oxygen saturation (Figure 4B,C).</li>
	<li>Ventilate the animal mechanically.</li>
	<li>Adjust the respiratory rate to maintain end-tidal CO&#8322; values between 50 and 60 mmHg.
	<ol>
		<li>If capnography (end-tidal CO&#8322;) exceeds 60 mmHg, increase the respiratory rate to return values to the target range.</li>
	</ol>
	</li>
</ol>
4. Animal periprocedural monitoring conditions
<ol>
	<li>Monitor oxygen saturation continuously using a pulse oximeter. Maintain peripheral oxygen saturation (SpO&#8322;) above 95%. If SpO&#8322; falls below this threshold, check for selective (endobronchial) ventilation and correct tube positioning as needed.</li>
	<li>Monitor body temperature using a rectal thermal probe. Maintain body temperature at 37 &#176;C throughout the procedure through a heating pad.</li>
</ol>

The authors have no conflicts of interest to declare.

This study describes a video-assisted direct laryngoscopy technique for orotracheal intubation in rats using a commercially available video otoscope wirelessly connected to a smartphone. In this cohort, the method enabled successful intubation in all animals with a low rate of periprocedural complications, under the conditions tested.
Several technical features contributed to the observed procedural performance. The curved shape of the otoscope blade facilitated the displacement of oral debris...

Rats are widely used in experimental and translational research, and endotracheal intubation may be required for procedures that necessitate controlled ventilation1,2. However, reliable intubation in rats remains technically challenging due to their small oral cavity, narrow glottic opening, and anatomical angulation of the airway3,4,5.
Several approaches have been proposed to overcome these constraints6,7,8. Among them, blind intubation techniques have been refined in recent years and can improve success rates when specific positioning strategies are used; nevertheless, these methods remain highly operator-dependent and continue to carry a risk of failure or side-effects such as esophageal misplacement or airway injury3. Video-assisted techniques have been developed to improve visualization of the glottis and enhance procedural safety. While these approaches provide effective airway visualization, they often require specialized endoscopic equipment, external monitors, inhalation anesthesia systems, or custom-modified devices, which may limit accessibility and routine implementation7,9,10.
Despite these advances, many methods remain constrained by technical complexity, invasiveness, or reliance on costly or modified equipment that is difficult to reproduce across laboratories. The primary advantage of the present approach is the provision of low-cost airway visualization without the need for device modification. This protocol is intended for laboratories requiring low-cost, visualization-assisted intubation without access to specialized endoscopic systems.
The present protocol describes a simple, reproducible, and low-cost method for orotracheal intubation in rats using a commercially available video otoscope equipped with an integrated light source and wireless smartphone connectivity. Unlike previously described video-assisted approaches, this technique requires no device modification (e.g., the addition of a blunt-tipped plastic blade fashioned from a modified 1 mL syringe cap)11 and avoids the need for external imaging systems (e.g., computer-based displays)9,12, while providing clear, real-time visualization of the glottic opening. This approach, therefore, represents an accessible alternative to higher-cost visualization systems and may facilitate airway management in settings where dedicated endoscopic equipment is not available.

<table><tbody><tr><td>0.1 mL syringe for anaesthesia</td><td>Fischer</td><td>Not applicable</td><td>Subcutaneous injection of buprenorphine</td></tr><tr><td>1 mL syringe for anaesthesia</td><td>Fischer</td><td>Not applicable</td><td>Intraperitoneal injection of xylazine</td></tr><tr><td>22G needle for anaesthesia</td><td>TERUMO</td><td>Not applicable</td><td>Intraperitoneal injection of xylazine</td></tr><tr><td>Adjustable laptop stand&amp;nbsp;</td><td>Amazon</td><td>Not applicable</td><td></td></tr><tr><td>Anesthesia induction chamber</td><td>Temsega</td><td>Not applicable</td><td></td></tr><tr><td>Animal ventilator</td><td>Physiosuite</td><td>Not applicable</td><td></td></tr><tr><td>Arterial catheter guide</td><td>Vygon</td><td>Not applicable</td><td></td></tr><tr><td>Buprenorphine</td><td>VIRBAC</td><td>Not applicable</td><td>0.05 mg/kg</td></tr><tr><td>Capnograph</td><td>Physiosuite</td><td>Not applicable</td><td></td></tr><tr><td>Endotracheal tube&amp;nbsp;</td><td>INSTECH</td><td>FTSS-16S-76</td><td>Gavage tube of 2.8 mm diameter</td></tr><tr><td>Heating pad</td><td>Physiosuite</td><td>Not applicable</td><td></td></tr><tr><td>Induction chamber</td><td>Temsega</td><td>Not applicable</td><td></td></tr><tr><td>Isoflurane</td><td>IsoVet</td><td>Not applicable</td><td></td></tr><tr><td>Isoflurane&amp;nbsp; vaporizer&amp;rsquo;s</td><td>Temsega</td><td>Not applicable</td><td></td></tr><tr><td>Otoscope Vitococo</td><td>Amazon</td><td>Otoscope Oreille 1920P Camera</td><td></td></tr><tr><td>Saturation oxymeter&amp;nbsp;</td><td>Physiosuite</td><td>Not applicable</td><td></td></tr><tr><td>Scavanger&amp;nbsp; system</td><td>F/air evacuation filter cartrigde</td><td>Not applicable</td><td></td></tr><tr><td>Smartphone&amp;nbsp;</td><td>Samsung</td><td>Galaxy A52S</td><td></td></tr><tr><td>Temperature probe</td><td>Physiosuite</td><td>Not applicable</td><td></td></tr><tr><td>Velpeau band&amp;nbsp;</td><td>Velpeau</td><td>Not applicable</td><td>Cotton crepe bandage, 10 cm &amp;times; 4 m (approximately 120 cm used)</td></tr><tr><td>Ventilation mask&amp;nbsp;</td><td>Temsega</td><td>Not applicable</td><td></td></tr><tr><td>Xylazine</td><td>VIRBAC</td><td>Not applicable</td><td>5 mg/kg</td></tr></tbody></table>

video-assisted orotracheal intubation in rats using a low-cost smartphone-connected otoscope

Video-Assisted Orotracheal Intubation in Rats Using a Low-Cost Smartphone-Connected Otoscope

Reliable endotracheal intubation is essential for experimental procedures in rats that require controlled ventilation, particularly during thoracic and cardiovascular surgeries. However, airway management in rats remains technically challenging due to anatomical constraints and limited accessibility of available intubation techniques. The goal of this protocol is to describe a simple, low-cost method for orotracheal intubation in rats using video-assisted direct laryngoscopy successfully applied in a cohort of 50 rats.
This protocol uses a commercially available video otoscope with an integrated light source and wireless smartphone connectivity to provide real-time visualization of the upper airway. The method does not require device modification or specialized imaging systems. Adult rats are anesthetized with xylazine and isoflurane, positioned on an inclined intubation platform, and intubated under continuous visual guidance using a flexible guide and an endotracheal tube. Correct tube placement is defined by bilateral thoracic expansion, stable oxygen saturation (SpO&#8322;), and a consistent end-tidal CO&#8322; (capnography) waveform. Following intubation, mechanical ventilation is initiated without positive end-expiratory pressure, and the tidal volume was set at 7.5 mL/kg. In this cohort, the technique enabled rapid intubation with a high first-attempt success rate and was associated with a low incidence of peri-procedural complications. Continuous visualization may reduce the risk of esophageal intubation and airway trauma. These findings support the feasibility of this approach under the conditions tested, without extrapolation beyond this experimental setting.

Intubation success was defined as correct endotracheal tube placement confirmed after connection to the ventilator by bilateral chest expansion, stable oxygen saturation (SpO₂), and a consistent end-tidal CO₂ waveform.
Orotracheal intubation was performed by a single operator over 3 months in a consecutive cohort of 50 adult rats. Five additional animals were used during a preliminary phase to establish and refine the protocol and were not included in the final analysis. No animals were exclud...

This protocol describes a simple, low-cost, video-assisted method for orotracheal intubation, enabling rapid and visually guided intubation in adult rats under isoflurane anesthesia.

Reliable endotracheal intubation is essential for experimental procedures in rats that require controlled ventilation, particularly during thoracic and ...

Rats are widely used in experimental and translational research, particularly in surgery model requiring control and mechanical ventilation. Airway management in rats remain technically challenging due to the small and narrow cavity, glottic opening on anatomical angulation of the airway. Several intubation techniques have been described, including blind methods and video-assisted system.While effective, these approaches often require operator expertise, specialized equipment, or device modification. In this video, we present a simple, low-cost, and reproducible method for orotracheal intubation in rats using a commercially available video otoscope under isoflurane anesthesia. The required equipment for this procedure includes an inclined intubation platform set at 45 degrees, which allows stable positioning during the procedure, a video otoscope with integrated light source and wireless display, a Velcro band, a flexible guide wire, and a suitable size endotracheal tube.And finally, a small animal ventilator. Following intraperitoneal injection of xylazine 5 milligram per kilogram for anesthesia and subcutaneous buprenorphine 0.05 milligram per kilograms, animals were placed in an induction chamber with isoflurane for 15 minutes. Tighten the Velcro band around the intubation platform.Then, slide the ventilation mask underneath the Velcro band to ensure oxygenation of the animal during the intubation procedure. Place the rat in the supine position on the 45-degree inclined intubation platform, then secure the upper incisors to stabilize head extension using the Velcro band. Confirm adequate anesthetic depth by verifying the absence of withdrawal reflexes in the forelimbs, hindlimbs, and tail in a response to natural stimulation.Gently extend the tongue and introduce the video otoscope into the oral cavity. Press the tongue against the floor of the mouth and advance until the soft palate is rised. Apply gentle traction to expose the vocal cords.Insert the flexible guide wire through the vocal cord and advance the endotracheal tube over the guide into the trachea until a characteristic tactile sensation corresponding to the tracheal rings is perceived. Remove the guide wire and connect the tube to the ventilator. After the intubation, confirm correct placement of the endotracheal tube by observing bilateral thoracic expansion, a stable capnography waveform, and adequate oxygen saturation.Orotracheal intubation was successfully achieved in all 50 animals. The procedure duration was consistently under one minute, with a 100%first attempt success rate. Heart rate remains stable throughout the procedure.Also, oxygen saturation remains stable throughout the procedure, with value consistently above 95%Capnography show regular waveforms, with end-tidal CO2 maintained between 50 and 60 millimeters of mercury. Tidal volume remains stable during mechanical ventilation. Microscopic examination of the trachea following extubation reveal no injuries.Also, histological examination of the trachea following extubation reveal no visible epithelial damage attributable to intubation procedure. This protocol provide a simple and accessible approach for orotracheal intubation in a rat using a video otoscope without device modification. Continuous visualization reduce operator dependence and minimize the risk of oesophageal intubation.The technique is particularly suitable for experimental model requiring control ventilation. One limitation of this method is the requirement for proper tongue positioning, which is critical for optimal visualization. Additionally, validation was performed in adult rats.Adaptation may be necessary for small animal. Overall, this low-cost, minimally invasive technique represents a reliable method for rats airway management in experimental research.

video-assisted-orotracheal-intubation-rats-using-low-cost-smartphone

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Learn a low-cost video-assisted orotracheal intubation method for rats using a smartphone-connected otoscope. This protocol enables rapid, safe airway management with real-time visualization for experimental surgery.

Video-Assisted Orotracheal Intubation in Rats Using a Low-Cost Smartphone-Connected Otoscope

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