Exotic companion mammal intubation and anesthesia (Proceedings)
Endotracheal intubation is the placement of a tube that extends from the oral cavity into the trachea. It is indicated for the administration of oxygen and inhalation anesthesia, to ensure a patent airway in unconscious patients, to provide ventilatory assistance, and to provide a conduit into the trachea to permit diagnostic and therapeutic measures (e.g. endoscopy, tracheal wash, direct instillation of medications). Intubation provides better airway control than a face mask and minimizes the risk of aspiration of foreign materials. This is especially important for complex and prolonged procedures, when complications such as respiratory obstruction and hypoventilation are more likely to occur.
Blind intubationBy properly positioning the head and neck, the pathway from the oropharynx to the trachea is straightened so that an endotracheal tube can be placed without direct visualization of the larynx. This is possible with the aid of laryngeal palpation, patient response (i.e. coughing, gagging), and listening for patient respiration through the endotracheal tube itself. Under special circumstances, a tube may need to be inserted using a transtracheally-placed catheter as a guide.
Visualization of the larynx is aided by hyperextension of the head and neck. Usually an assistant must open the mouth an oral speculum or gauze placed around the upper and lower incisors. A small-bladed (e.g. Miller 0 neonatal) laryngoscope is used to depress the tongue and elevate the soft palate. Once the vocal folds are visualized, the tube is placed. An atraumatic stylet (polypropylene catheter) can be placed through the tube so its tip extends beyond the end of the endotracheal tube in order to guide the tube through the vocal folds.
A canine otoscope can be used instead of a laryngoscope in smaller patients. After adequate visualization is achieved, a 5-fr polypropylene urinary catheter is guided down the otoscope between the vocal folds and advanced into the trachea. At this point, the otoscope is removed and the tracheal tube is threaded over the catheter and into the larynx. The catheter guide is then removed.
Direct visualization of the trachea can also be achieved using an endoscope. The endoscope is positioned so the larynx is in view, and an endotracheal tube is passed parallel to the scope and into the trachea. Further, with some scopes it is possible to put the endoscope directly inside the endotracheal tube like a stylet, and to visually guide the scope/tube assembly into the trachea.
Comments on individual species
Direct placement of an endotracheal tube in ferrets usually requires two people. Over-the-endoscope intubation of ferrets simplifies intubation because it does not require the jaws to be opened wide or the tongue to be pulled forward. The endoscope/tube combination is rigid enough force the tongue forward at its base, exposing the glottis. The tube and scope are advanced over the epiglottis and into the trachea. Either a 2 mm Cole or 2.5 mm straight endotracheal tube is recommended with this technique.