The overall goal of this procedure is to safely and effectively intubate rabbits to ensure a patent airway during general anesthesia. This method can be used for research projects requiring general anesthesia in rabbits, but also has a broad application for a variety of clinical settings. The main advantages of this technique are that is it non-invasive, relatively inexpensive, easy to learn and results in the direct intubation of the trachea.
Endotracheal intubation in rabbits can challenging due to their unusual anatomy. But, this approach is a simple and repeatable procedure that uses inexpensive supplies and easily identifiable landmarks. Before beginning the procedure, cut the non-rounded end of a five-French polypropylene catheter to a total length of eight to 10 inches and clearly mark the cut end of the tubing to indicate the end that should not be inserted into the trachea.
Load a size zero or one Miller laryngoscope blade onto the laryngoscope and verify that the laryngoscope light is functional. Measure an appropriately sized uncuffed endotracheal tube from the incisors to the thoracic inlet to determine the proper length for the endotracheal tube insertion, and apply sterile lubricant to the end of the tube. After confirming the appropriate level of sedation by toe pinch, apply ointment to the eyes of a four-month-old three to 3.3 kilogram New Zealand white rabbit.
Position the rabbit sternally on the preparation table with its head slightly extended over the edge of the table and with the head and spine in straight alignment. Lifting up the head, use a gauze pad to pull the tongue laterally to the right lower incisors in the diastema. And entering from the left side of the animal, use the right hand to place the laryngoscope and blade into the mouth behind the incisors.
Follow the roof of the mouth caudally with the tip of the blade until the soft palette is visible. Then, bending the wrist and holding the instrument downward, tip the laryngoscope forward while extending the animal's head back and the neck forward to maintain an open airway and to view the larynx. It is critical to obtain clear visualization of the larynx to ensure that the guide catheter is directed into the airway.
Maintaining the view of the glottis, release the tongue and switch the laryngoscope blade to the left hand. Advance the rounded tip of the guide catheter through the opening past the larynx visualizing the passage between the vocal cords until the catheter comes to a natural stop at the tracheal bifurcation. Thread the endotracheal tube over the catheter and advance the tube until there is resistance from the vocal cords.
The riskiest part of the procedure is the threading of the endotracheal tube over the guide catheter. If the endotracheal tube connector catches on the guide catheter, it can force the catheter further into the airway potentially causing trauma. When the tube is in place, use a one-milliliter syringe to instill 0.25 milliliters of 2%lidocaine into the tube opening to locally anesthetize the vocal cords preventing laryngospasm.
After two minutes, gently rotate the endotracheal tube while advancing it through the vocal cords. Once the tube has passed the vocal cords, remove the laryngoscope blade and catheter taking care not to dislodge the tube. Verify the correct placement of the endotracheal tube by observing the airflow and secure the tube with umbilical tape tied around the tube and head.
Then, attach the anesthesia circuit and auscult both sides of the thorax while giving breaths to assure ventilation to both sides of the lung. After one demonstration by an experienced trainer, trainees new to the intubation technique, which is easy to learn and to perform, typically achieve success within one to three attempts. As with any method of intubation, it's important to closely monitor the animal during the anesthesia and recovery periods for any potential complications or airway obstructions.
Once mastered, this technique can be performed quickly and reliably by a single individual in any clinical setting and can be easy taught to technical staff with a short time to proficiency. After watching this video, you should have a good understanding of how to safety intubate rabbits to maintain a patent airway under general anesthesia.
