Lighted Stylet Assisted Tracheal Intubation

Various types of stylets are commonly available as adjuncts to endotracheal intubation, including the traditional malleable stylet, the gum elastic bougie (see the first video below), optical stylets, and lighted stylets (see the second video below). This article discusses the use of lighted stylets for tracheal intubation.

Lighted stylets available include Light Wand (Vital Signs Inc, Totowa, NJ), Trachlight (Laerdal Medical, Wappingers Falls, NY), Tube Stat lighted stylet (Xomed, Jacksonville, FL), and others.[1, 2]  These devices rely on the principle of transillumination of the soft tissues of the neck. The light serves to guide the tube into the larynx; direct visualization of the glottis is not required for successful use.[3]

Intubation under direct vision may be difficult or impossible in 1-3% of surgical patients and 0.05-3.5% of obstetric patients.[4, 5]  Light-guided intubation using transillumination has proved to be simple and effective. When the tip of the lightwand is placed inside the glottis, a bright glow can be seen in the anterior soft tissue of the neck. In contrast, if the lightwand is placed in the esophagus, no transillumination is observed.

Benefits of light-guided tracheal intubation include utility in obstructed conditions, low acquisition costs, and disposable components that eliminate the need for disinfection of the equipment. A distinct disadvantage is that room lights must be dimmed during the procedure. The procedure also requires a fair amount of user experience.[1, 6, 7, 8, 9]

A patient with a difficult airway in whom direct laryngoscopy has failed is a candidate for light-guided tracheal intubation.[9, 10] A trauma patient with bleeding in the oropharynx is a prime example.

A patient who has been pharmacologically paralyzed and cannot be intubated with direct laryngoscopy is also a candidate for light-guided tracheal intubation.

The lighted stylet can also be used in successfully completing a difficult nasotracheal intubation.[11] An advantage of this technique over nasotracheal intubation is that it can be used in an apneic patient.

Lighted stylet intubation is a blind approach. Therefore, it should be avoided in patients with an expanding neck mass, oropharyngeal tumors, infections (epiglottitis), morbid obesity (because of the difficulty transilluminating soft tissues of the neck), or airway compromise presumed to be caused by a foreign body.

In addition, since the room lights must be dimmed during the procedure, this device may not be appropriate in certain critical or trauma situations.[1, 12]

In a study involving 62 adult patients who underwent thoracic surgery using double-lumen endobronchial intubation, Chang et al compared the use of a GlideScope with the use of a lighted stylet with respect to intubation time, success rate of first intubation attempt, difficulty of advancing the tube toward the glottis, and postoperative sore throat and hoarseness.[13] They found that the lighted stylet allowed easier advancement of the tube toward the glottis in the oropharyngeal space and a shorter intubation time.

In a randomized clinical study that included 284 patients undergoing general anesthesia, Park et al assessed the effectiveness of a lighted stylet against that of a simple stylet during tracheal intubation with direct laryngoscopy.[14]  Compared with the simple stylet, the lighted stylet yielded a higher success rate of tracheal intubation at the first attempt (99% vs 90%) and a lower incidence of mucosal bleeding (13% vs 25%). Total intubation time and degree of postoperative sore throat did not differ significantly between the two groups.

Equipent required for lighted stylet–assisted tracheal intubation includes the following:

• Lighted stylet (see the image below)
• Supplemental oxygen
• Ambu bag
• Suction equipment

Also required are the following:

• Automated blood pressure cuff (set to cycle every 5 min)
• Three-lead electrocardiographic (ECG) monitoring
• Constant pulse oximetry
• Intravenous access

Anesthesia

If the patient is awake, spray the oropharynx and hypopharynx with lidocaine or benzocaine spray, and administer sedation as indicated. Topical anesthesia may be achieved by use of lidocaine spray 10%, Cetacaine (benzocaine 14%, tetracaine 2%, butyl aminobenzoate 2%), or Hurricaine (benzocaine 20%).

Procedural sedation or rapid sequence intubation may also be required.

Positioning

If cervical spine injury is not a concern, place the patient's head and neck in a relatively extended position. This pulls the epiglottis away from the posterior pharyngeal wall and allows maximal exposure of the anterior neck, thereby enhancing visualization of the transilluminated light.

If cervical spine injury is a concern, place the patient's head in a neutral position.[15]

A towel roll beneath the shoulders aids in positioning, especially in obese patients or those with a short neck.

If there is difficulty passing the lightwand into the trachea, it may be hung up on the epiglottis, which can be lifted off the posterior pharyngeal wall with a jaw-lift maneuver.[16]

Procedure

The practitioner should stand at the head of the patient. If this is not possible, the patient can be approached from either side.

Insert the lubricated lighted stylet into an endotracheal tube 2.5 mm or larger (pediatric stylets are available) until the bulb lies just distal to the Murphy eye but does not protrude from the end of the tube. Bend the tube and stylet in the shape of a hockey stick, with a 90° curve beginning just proximal to the tube cuff.[1, 2]

Different bend angles have been used for this procedure. A prospective randomized study found that in children between the ages of 4 and 6 years, a 90º bend angle yielded a higher success rate and a lower incidence of esophageal intubation as compared with a 70º angle.[17]  A previous pilot study comparing three bend angles (70º, 80º, and 90º) found that the angles did not differ significantly with regard to success rate, through there was a trend toward improved success with the latter two angles.[18]  Postoperative sore throat was significantly less with the 80º angle than with the 90º angle.

The patient's head and neck should be in the neutral position or slightly extended. Grasp the patient's jaw near the corner of the mouth using the thumb, index, and middle fingers. Lift the jaw to elevate the tongue and epiglottis. (See the video below.)

A glow in the midline of the neck indicates the location of the tube tip (see the image below).

Applying cricoid pressure and dimming the lights may enhance transillumination. Positioning is optimal when the glow can be seen in the midline of the neck, just below the level of the thyroid prominence.

Next, slide the endotracheal tube off while holding the stylet steady, and advance into the trachea up to the proper depth. If the glow is located off the midline, withdraw the unit 2 cm and reposition as indicated by the light. If no light or only a dim light is seen, the tube is probably in the esophagus. If this is the case, withdraw the tube, apply cricoid pressure, and, if necessary, extend the head slightly.

Once the lighted stylet has been removed and the tube placement has been verified by means of auscultation and capnography, secure the endotracheal tube with a commercially available tube holder or adhesive tape.[1, 6, 2]

​Pearls

Some authors suggest that for novices, conventional laryngoscopy may be superior to the use of transillumination with a lighted stylet. However, for practitioners experienced in its use, transillumination can be as reliable as conventional laryngoscopy, and it can be used in apneic patients.

Positioning is correct when the glow emanates from the midline, just below the level of the thyroid prominence. In extremely thin patients, transillumination may be seen even when the tube is the esophagus. To tell the difference, note that if the tip is in the esophagus, the glow is diffuse, as opposed to the well-circumscribed glow of intralaryngeal placement.

A controlled study by Muslu et al highlighted the successful use of ultrasonography (US) as an adjunctive method for tracheal tube placement confirmation within 3 seconds of intubation in 150 adult surgical patients.[19] In this study, tracheal tube position was successfully identified by means of US in 75 of 75 tracheal placements and 75 of 75 esophageal placements, for a sensitivity of 100% and a specificity of 100%.

No complications directly related to the use of the tracheal light have been cited in the literature; this may be a reflection of the relatively limited use of this technique.[1, 2]