Alternative Technique for Nasotracheal Intubation Using a Flexible Fiberoptic Scope

Abstract

In oral maxillofacial surgery, the endotracheal tube (ETT) is often inserted nasotracheally to provide surgeons a better view and easier access to the oral cavity. Use of a flexible fiberoptic scope is an effective technique for difficult intubation. While the airway anatomy can be observed as the scope is advanced, the ETT tip cannot be observed with the traditional method. It is occasionally difficult to advance the ETT beyond the glottis as impingement of the ETT tip may occur. We devised a new nasotracheal intubation technique using a fiberoptic scope. In this novel technique, the ETT and fiberoptic scope are inserted into the pharyngeal space separately through the right and left nasal cavities. This permits continuous observation of the glottis as the ETT is advanced into the trachea. The main advantage of this technique is that the ETT tip is visualized as it is advanced, which helps avoid impingement of the ETT. If resistance is noted, the ETT can easily be rotated or withdrawn without causing laryngeal damage, leading to safe and smooth intubation. This novel technique allows advancement of the ETT under continuous indirect vision, thus minimizing contact of the ETT with the laryngeal structures and aiding in unhindered passage into the glottis.

Recently, video laryngoscope devices, such as the Pentax-AWS (Pentax Corporation), have become more widely used for difficult intubations.^1–3 Improved visualization often facilitates easy placement of the endotracheal tube (ETT) into the trachea. However, use of these devices can be impossible in some patients with significant limited mouth opening (eg, infection, trismus, temporomandibular joint ankylosis) as these devices require sufficient space for the blade to be inserted into the mouth. Moreover, the blades of these devices should not be inserted into the mouth in some cases of oral cancer as their use may stimulate bleeding or inflammation of the friable tissues. Therefore, intubation using a flexible fiberoptic scope is a commonly used technique for these types of difficult airway cases.^4,5

In oral and maxillofacial surgery, the ETT is often inserted nasotracheally to provide a better view for surgeons and to allow easy access to the oral cavity.³ In our clinical practice, the nasotracheal tube is first inserted into the pharynx through the nares and nasal cavity. The flexible fiberoptic scope is then inserted through the ETT, and the scope tip is carefully directed past the glottis and into the trachea under indirect vision. Once intratracheal positioning of the scope is confirmed, the ETT is advanced blindly into the trachea, guided by the fiberoptic scope. By advancing the tip of the fiberoptic scope under indirect vision, we can observe the pharyngeal, laryngeal, and tracheal anatomy (Figure 1a). Successful placement of the ETT within the trachea is visually confirmed with the scope (Figure 1b). However, the tip of the ETT cannot be observed as it is advanced along the length of the fiberoptic scope using this blind technique, which may lead to difficulties if impingement of the ETT tip occurs. We have devised a new nasotracheal intubation technique that addresses these issues.

Figure 1.

Fiberoptic view during nasotracheal intubation using the traditional fiberoptic scope technique (a, b) and our new technique (c). (a) Indirect visualization of the glottis prior to advancement of the endotracheal tube (ETT). (b) Tip of the ETT as it is advanced blindly along the fiberoptic scope. Passage through the glottis cannot be visually confirmed, so the ETT could become impinged upon on a trachea ring or laryngeal anatomy.

(c) Advancement of the ETT through the glottis under continuous indirect visualization.

METHODS

In this novel technique, the ETT is carefully advanced through the nasopharynx and into the posterior oropharynx while the flexible fiberoptic scope is inserted through the contralateral side of the nasal cavity. This allows the ETT and the scope to be advanced separately, and the glottis can be continuously observed using the scope as the ETT is advanced between the vocal cords into the trachea. The main advantage of this technique is that the ETT tip can be observed at the glottis as it is advanced to help identify and avoid impingement upon the laryngeal structures (ie, vocal cords). Insertion of the ETT is indirectly monitored using the flexible fiberoptic scope with full view of the larynx (Figure 1c). This technique allows advancement of the ETT under continuous indirect vision, thus minimizing contact of the ETT with the laryngeal structures and aiding in unhindered passage through the glottis.

DISCUSSION

There are times when fiberoptic intubation can be difficult. Induction of general anesthesia causes relaxation of the airway musculature and can lead to collapse of the airway as the soft palate, tongue, and epiglottis approximate the posterior pharyngeal wall. This leaves little air space left in the pharynx to successfully maneuver the scope tip and locate the glottis.

Furthermore, it is possible that tracheal intubation fails despite successful insertion of the fiberoptic scope into the trachea. The ETT can deviate away from the path of the scope as it is advanced into the trachea, enabling the ETT tip to become lodged on the laryngeal structures. This can lead to difficulty successfully advancing the ETT over the fiberoptic scope and into the trachea. Moreover, if care is not taken to ensure the fiberoptic scope remains within the trachea, the ETT could cause displacement of the scope upon advancement and be inadvertently inserted into the esophagus despite the scope's correct initial placement in the trachea. Difficulty advancing the ETT has been reported to occur in 20%–90% of patients.^4–6 The size of the tongue and length of the epiglottis have been correlated with the incidence of ETT impingement. Deformity or distortion of the upper airway can also obstruct passage of the ETT over the fiberoptic scope.^4,7 Repeated attempts to advance the ETT over the fiberoptic scope and into the trachea might increase the risk of injury to the glottic tissues. Several maneuvers have been proposed to solve this problem, such as thrusting the jaw forward or rotating the ETT, which might reduce resistance by releasing the ETT tip that is impinging on the laryngeal structures.^6–8

It is not necessary to pass the fiberoptic scope through the nasal cavity (nasolaryngeal insertion) to visualize the ETT tip. Orolaryngeal insertion of the scope might be beneficial to permit visualization of the ETT tip without risking nasal bleeding. However, we believe that nasolaryngeal insertion of the fiberoptic scope allows easier passage through the nasal cavity and improved observation of the ETT at the same angle as compared with orolaryngeal insertion. The view obtained using the fiberoptic scope is usually more stable when nasolarygneal insertion is used as the scope is somewhat supported by the nasal anatomy. We feel this approach positively affects the success rate of tracheal intubation and might reduce the risk of postoperative sore throat.^6,10

Occasionally, it might be difficult to manipulate the ETT and direct it into the trachea. For example, the ETT may become stuck on a tracheal ring or the vocal cords despite the perfect view for intubation. In such a situation, the operator can ask for assistance visualizing the larynx and/or intubating. To help avoid this situation, we have found that 2 technical options are useful: (1) insert 1 scope into the ETT and a second scope into the contralateral side of the nasal cavity, or (2) insert an introducer (ie, tube exchanger) into the ETT while the ETT tip is visualized with the scope. Either approach permits easier manipulation of the ETT tip and passage through the glottis. Moreover, we have also solved this problem by rotating and/or withdrawing the ETT without laryngeal damage, which led to safe and smooth intubation.⁷

We have used this technique effectively for intubating conscious and unconscious patients. Care must be taken not to damage the pharyngeal tissues when this technique is utilized after induction of general anesthesia due to the potential for reduced pharyngeal air spaces. For awake intubations, the use of sedatives and local anesthetics are needed to maintain spontaneous ventilation, facilitate patient cooperation, and to enable the patient to tolerate passage of the fiberoptic scope to facilitate intubation.⁸

Generally, nasotracheal intubation under direct vision requires alignment of the oral cavity, pharynx, and larynx (ie, the 3 airway axes), and the glottis must be visible.⁹ However, aligning these axes is not as important in this technique. Instead, it is more important to secure a large pharyngeal space for maximal visualization of the field while operating the scope for intubation by placing the patient in the supine position without a pillow. In addition, emergency airway equipment, including a video laryngoscope and surgical airway/tracheostomy kit, should be readily available for use in case the procedure fails, and the patient's airway is lost.

CONCLUSION

This new technique allows advancement of the ETT under continuous indirect vision with a flexible fiberoptic scope, thus minimizing contact or impingement of the ETT with the laryngeal structures and aiding in unhindered passage through the glottis. We are confident this novel approach should be considered for use in all nasotracheal intubation cases.