Retromolar flexible fiber-optic orotracheal intubation: a novel alternative to nasal intubation and tracheostomy in severe trismus.

Ensuring control and protection of the airway for surgical procedures requiring general anesthesia is the cornerstone of clinical anesthesia practice. Successful tracheal intubation is absolutely needed for head and neck cancer surgery because access to the airway is shared by surgeons and anesthesiologists. The approach, oral or nasal, depends on surgical requirements and the patient’s ability to open the mouth fully. Orotracheal intubation is generally the preferred option. In patients with restricted mouth opening, however, this procedure may be very challenging. In severe trismus (Figure 1), it is difficult or even impossible to insert a laryngoscope or an endotracheal tube between the teeth (Figure 2). Originally defined as reduced opening of the jaws specifically caused by spasm of the muscles of mastication, trismus currently refers to limited mouth opening from any etiology. It may be caused by various pathologies, such as tumors, infections, trauma, or as a sequela from surgeries or radiotherapy involving the temporomandibular joint, mandible, maxilla, teeth, gingiva, and oral cavity. Patients with trismus are encountered with increasing frequency in clinical practice. The prevalence of trismus has been reported to be from 5% to 38% after surgery and radiotherapy for head and neck cancers. When mouth opening is severely restricted, nasotracheal intubation is the customary alternative. Unfortunately, some patients with severe trismus also have concomitant contraindications to nasal intubation. Thus, the nasal approach for intubation is not acceptable for surgical procedures involving the nose, paranasal sinuses, maxilla, nasolacrimal ducts, or transphenoidal pituitary. Other contraindications include nasal tumors, nasal infections, basilar skull fractures, and coagulopathy. Traditionally, when both oral and nasal intubation cannot be performed because of concomitant trismus and contraindications to nasal intubation, control of the airway through a surgical tracheostomy is an option of last resort. To avoid the need for tracheostomy, an invasive procedure with many potential serious complications, we described a novel technique using the retromolar space as an entry to perform flexible fiber-optic orotracheal intubation (Figure 3) in these challenging cases. Located between the back of the last molar and the ascending ramus of the mandible, in the large majority of patients, even with complete mandibular occlusion, the retromolar space is almost invariably sufficiently large to accommodate a 7.0-mm cuffed tracheal tube. We have reported 3 cases of retromolar placement of tracheal tubes to overcome severe trismus in patients presenting different challenges in airway management. In the first report, the retromolar space was used as the point of insertion for oral intubation in a 50-year-old woman with restricted mouth opening not allowing passage of a 6.0 mm endotracheal tube for dacryocystorhinostomy. Apart from the severe trismus, she did not present any other feature of difficult airway. In the second report, retromolar intubation was performed to secure the airway in an 8-year-old boy who presented not only with severe trismus and bilateral nasal stenoses, but also severe airway distortion because of aggressive mandibular rhabdomyosarcoma. Finally, the retromolar space was used to insert a 35Fr double-lumen tube for lung isolation in a patient with trismus, a short bulky neck, prominent upper teeth, and limited neck extension. Since then, we have extended the application of this approach to achieve atraumatic oral intubation in other causes of difficult airway. Thus, by bypassing the oral cavity, the retromolar approach prevents intubation injury to loose teeth in patients with poor dentition and minimizes intubation trauma in patients with tumors of the tongue and oral cavity. The successive steps in performing flexible fiber-optic retromolar intubation are described in detail in the accompanying video. Before intubation, inserting nasopharyngeal airways of various sizes into the space is done to ensure that there is enough room to accommodate *Corresponding author: A. Truong, Department of Anesthesiology and Perioperative Medicine, University of Texas MD Anderson Cancer Center, 1400 Holcombe Boulevard, Unit 409, Houston, TX 77030. E-mail: [email protected]