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Lightwand intubation using the Trachlight^TM: a brief review of current knowledge

[Intubation avec le stylet lumineux Trachlight^TM : un aperçu des connaissances actuelles]

Felice Agrò, MD^*, Orlando R. Hung, MD, Rita Cataldo, MD^*, Massimiliano Carassiti, MD^* and Stefano Gherardi, MD^*

^* From the Department of Anaesthesia, University School of Medicine, Campus Bio-Medico, Rome, Italy, and the
Department of Anaesthesia and Phamacology, Dalhousie University, Halifax, Nova Scotia, Canada.

Address correspondence to: Dr. Felice Agrò, Department of Anaesthesia, University School of Medicine Campus Bio-Medico, Via Longoni 69/83, 00155 Rome, Italy. Phone: 039-06-22541522; Fax: 039-06-22541444; E-mail f.agro{at}unicampus.it

	Abstract

TOP Abstract Introduction Developments leading to the... Description of the TL Intubation technique with the... Oral intubation Nasal intubation Clinical applications Associated techniques Difficulties, limitations and... Conclusion References

 
Purpose: About 1% to 3% of laryngoscopic intubations can be difficult or impossible. Light-guided intubation has been proven to be an effective, safe, and simple technique. This article reviews current knowledge about the newer version lightwand: the Trachlight^TM (TL).

Source: To determine its clinical utility and limitations, we reviewed the current literature (book and journal articles) on the TL since its introduction in 1995.

Principal findings: TL has been shown to be useful both in oral and nasal intubation for patients with difficult airways. It may also be useful in "emergency" situations or when direct laryngoscopy or fiberoptic endoscopy is not effective, such as with patients who have copious secretions or blood in the oropharynx. TL can also be used for tracheal intubation in conjunction with other devices (laryngeal mask airway -LMA-, intubating LMA, direct laryngoscopy). However, TL should be avoided in patients with tumours, infections, trauma or foreign bodies in the upper airway.

Conclusions: Based on the clinical reports available, the TL has proven to be a useful option for tracheal intubation. In addition, the device can also be used together with other intubating devices, such as the intubating LMA and the laryngoscope, to improve intubating success rates. A clear understanding of the principle of transillumination of the TL, and an appreciation of its indications, contraindications, and limitations, will improve the effectiveness of the device as well as reducing the likelihood of complications. Finally, regular practice with the TL with routine surgical patients requiring tracheal intubation will further improve intubation success rates.

	Introduction

TOP Abstract Introduction Developments leading to the... Description of the TL Intubation technique with the... Oral intubation Nasal intubation Clinical applications Associated techniques Difficulties, limitations and... Conclusion References

 
MODERN methods of tracheal intubation (TI) emerged in the 20th Century.¹ Direct laryngoscopy (DL) has become the standard method of TI. Unfortunately, intubation under direct vision may be difficult or impossible in 1% to 3% of the general surgical population^2,3 and 0.05% to 3.5% of obstetric patients.^1,4 This is especially true in patients requiring emergency TI.¹ Furthermore, there is not a single method of airway assessment that can be used reliably to predict a difficult laryngoscopic intubation.^4,5 Over the years, alternative intubation techniques have been developed.

Light-guided intubation using the principle of transillumination has proven to be an effective and simple technique. When the tip of the lightwand is placed inside the glottis, a bright light glow can be seen easily in the soft tissue of the anterior neck. In contrast, if the lightwand is placed in the esophagus, no transillumination can be observed.¹ In a study with 479 patients using a novel lightwand device (Trachlight^TM -TL-, Laerdal Medical Corporation, New York, USA), Hung et al. reported only a 1% failure rate with a 92% success rate after the first attempt.⁴

	Developments leading to the TL

TOP Abstract Introduction Developments leading to the... Description of the TL Intubation technique with the... Oral intubation Nasal intubation Clinical applications Associated techniques Difficulties, limitations and... Conclusion References

 
Several versions of the lightwand have been introduced for TI since its introduction in 1959.^1,3–6 However, their designs had several limitations: 1) a poor light source; 2) a short lightwand which restricted its use to only short or cut endotracheal tubes (ETT); 3) the absence of a clamp or connector to secure the ETT onto the lightwand device; 4) the rigidity of the lightwand which hampered use of these devices for nasotracheal intubation (NTI); 5) most lightwands were designed for single use, increasing the cost of intubation. Due to these shortcomings, the TL was developed and became available in 1995.

	Description of the TL

TOP Abstract Introduction Developments leading to the... Description of the TL Intubation technique with the... Oral intubation Nasal intubation Clinical applications Associated techniques Difficulties, limitations and... Conclusion References

 
The TL (Figure 1) consists of a handle, a wand and a stylet. On the handle, a locking clamp accepts and secures a standard ETT connector. The distal end of the wand has a bright lightbulb. On the proximal end of the wand is a plastic connector with a release arm which allows its connection to the grooves in the handle. To accommodate ETT of different lengths, the length of the wand can be adjusted by sliding the connector along the handle. Enclosed within the wand is a stiff, retractable stylet which allows the wand to be shaped in a "hockey stick" configuration (Figure 2). Following retraction of the stylet, the wand becomes pliable, thus allowing the ETT to advance easily into the trachea with minimal trauma.

View larger version (178K): [in this window] [in a new window]   FIGURE 1 The TrachlightTM consists of three parts: a reusable handle, a flexible wand and a stiff, retractable stylet.

View larger version (143K): [in this window] [in a new window]   FIGURE 2 Correct "hockey stick" configuration of the TrachlightTM together with the endotracheal tube prior to intubation.

	Intubation technique with the TL

TOP Abstract Introduction Developments leading to the... Description of the TL Intubation technique with the... Oral intubation Nasal intubation Clinical applications Associated techniques Difficulties, limitations and... Conclusion References

Positioning
In a sniffing position, the epiglottis is almost in contact with the posterior pharyngeal wall, making it difficult for the TL to pass underneath the epiglottis. Therefore, we recommend that the patient's head and neck be placed in a neutral or relatively extended position.⁷ Furthermore, neck extension allows maximal exposure of the anterior neck, thus enhancing visualisation of the transilluminated light.¹ In our experience, in obese patients or in patients with an extremely short neck, placing a pillow under the shoulders and neck will further improve the ease of lightwand intubation. In patients with a potential cervical spine instability, the extended neck position is contraindicated. In these cases, the epiglottis can be lifted off the posterior pharyngeal wall with a simple jaw lift manoeuvre. The correct positioning of the lightwand is confirmed by the transillumination of the soft tissues of the anterior neck.⁸

Control of the ambient light
The light emitted by the TL is extremely bright, enhancing the transillumination of the neck. This is particularly true in thin patients, in which the light is so bright that it is possible to mistakenly interpret an esophageal intubation as an intratracheal placement. Therefore, all TL intubations should be performed under ambient light. Room lights should be dimmed only when transillumination of the neck is inadequate.¹

	Oral intubation

TOP Abstract Introduction Developments leading to the... Description of the TL Intubation technique with the... Oral intubation Nasal intubation Clinical applications Associated techniques Difficulties, limitations and... Conclusion References

 
With the patient lying supine, the jaw is lifted upward to elevate the epiglottis. Inserting the TL from the midline position can be problematic in patients with a thick chest or large breasts. It is, therefore, recommended that the TL be introduced from the lateral corner of the mouth and repositioned in the midline following its entry into the oropharynx. With the light turned on, a 90 rotation toward the anesthesiologist is performed in order to direct the ETT-TL tip into the glottic opening. The midline position is maintained while the device is gently advanced in a rocking motion along an imaginary arc. The light-guided tracheal intubation is a gentle technique! The device should not be forced against any resistance.

A faint glow seen above the thyroid prominence indicates that the tip of the ETT-TL is located in the glosso-epiglottic or epiglottic fold (Figure 3). If the ETT-TL enters the esophagus, no glow can be detected. A bright glow observed in the lateral aspect of the larynx indicates that the tip of the ETT-TL is placed in the piriform fossa (Figure 4), a redirection of the ETT-TL to the midline is then required.

View larger version (95K): [in this window] [in a new window]   FIGURE 3 Absence of the transillumination: TrachlightTM tip is in the glosso-epiglottic or epiglottic fold.

View larger version (56K): [in this window] [in a new window]   FIGURE 4 Lateral transillumination: TrachlightTM tip is in one of the two piriform recesses.

View larger version (36K): [in this window] [in a new window]   FIGURE 5 A central, clear and bright transillumination on the cricothyroid membrane suggests a correct positioning of the TrachlightTM tip into the laryngeal inlet: it is now safe to intubate the trachea.

	Nasal intubation

TOP Abstract Introduction Developments leading to the... Description of the TL Intubation technique with the... Oral intubation Nasal intubation Clinical applications Associated techniques Difficulties, limitations and... Conclusion References

Removal of the stylet before insertion of the TL into the ETT makes the ETT-TL pliable. A water-soluble lubricant is applied to the nostril to facilitate the passage of the ETT-TL. After advancing the tip of the ETT-TL into the oropharynx, the light is switched on and NTI is performed using transillumination as described in the oral intubating technique.

A potential limitation of NTI with the TL (without the internal rigid stylet) may be related to the difficulty in controlling the ETT-TL unit. The following options have been proposed to avoid this problem:^6,9,10 neck flexion during intubation; the use of a specialized ETT (Endotrol®, Mallinckrodt Inc, Pennsylvania, USA); inflation of the ETT cuff and the use of the rigid internal stylet. While these techniques may improve the light-guided NTI technique, its success still relies on the preparation of the patient and the skill of the operator.

	Clinical applications

TOP Abstract Introduction Developments leading to the... Description of the TL Intubation technique with the... Oral intubation Nasal intubation Clinical applications Associated techniques Difficulties, limitations and... Conclusion References

 
The TL may be a useful option in the case of a difficult or impossible laryngoscopic intubation for both anticipated and unanticipated situations (Table II).

The lightwand intubating technique is recommended as the first-line option in patients who can be ventilated but have had a failed laryngoscopic intubation (e.g., patients with Treacher-Collins,³ Pierre-Robin,^3,13 or with copious secretions or blood in the oropharynx).^3,6,14

Intubation with the TL appears to be associated with minimal trauma. A low incidence of mucosal injury (ten out of 479 patients using the TL vs 37 out of 471 patients using laryngoscopy) has been reported.³ In addition, there was no evidence of dental trauma associated with TL intubation. Thus, intubation using the TL may be also advantageous for patients with fixed dental appliances.

Since brightness of the TL lightbulb allows intubation under ambient light, the TL is useful even in the pre- hospital environment.^1–4,10

	Associated techniques

TOP Abstract Introduction Developments leading to the... Description of the TL Intubation technique with the... Oral intubation Nasal intubation Clinical applications Associated techniques Difficulties, limitations and... Conclusion References

 
The TL can also be used together with other devices, such as the laryngeal mask airway (LMA),^14–17 the intubating LMA (Fastrach^TM, Laryngeal Mask Company North America Inc., California, USA),¹⁸ DL,¹⁹ and a retrograde intubating technique⁵ (Figures 6, 7, 8).

View larger version (38K): [in this window] [in a new window]   FIGURE 6 The TrachlightTM used together with the LMA and the intubating LMA (FastrachTM).

View larger version (41K): [in this window] [in a new window]   FIGURE 7 The TrachlightTM used together with direct laryngoscopy.

View larger version (39K): [in this window] [in a new window]   FIGURE 8 The TrachlightTM used as an aid to the retrograde intubating technique.

Due to the design of the intubating LMA which permits the use of a larger ETT than the "classic" LMA, the success rate of blind TI through this device is substantially improved when compared to the classic LMA. Transillumination using the TL can further improve the success rate of intubation¹⁸ with the intubating LMA.

Biehl and Bourke¹⁹ showed that the TL could improve the view in the hypopharynx, and transillumination could assist in guiding the ETT into the trachea with DL.

In 27 patients with cervical spine instability, it has been reported that the TL can facilitate retrograde intubation.⁵ TI was successful in all patients using these techniques in association.

	Difficulties, limitations and contraindications

TOP Abstract Introduction Developments leading to the... Description of the TL Intubation technique with the... Oral intubation Nasal intubation Clinical applications Associated techniques Difficulties, limitations and... Conclusion References

 
Lightwand intubation is not without potential hazards.^1,2,4,18,20 The main complications, limitations and contraindications of the lightwand are summarized in Table III. Since TL intubation does not permit direct visualization of the anatomical structures, it should be avoided in patients with known abnormalities of the upper airway, such as tumours, polyps, infections (e.g., epiglottitis and retropharyngeal abscess), and trauma or presence of a foreign body in the upper airway.^2,4 In these cases, other alternatives using direct vision should be considered. A light-guided technique should not be attempted in an uncooperative awake patient, unless a bite block is used to minimize injury to the patient, the operator, and damage to the device.¹ In addition, great caution should be used in patients when transillumination of the anterior neck may not be adequate (e.g., grossly obese patients or patients with limited neck extension).^2,4 However, these contraindications and precautions may become irrelevant when airway compromise necessitates an emergency TI.

	Conclusion

TOP Abstract Introduction Developments leading to the... Description of the TL Intubation technique with the... Oral intubation Nasal intubation Clinical applications Associated techniques Difficulties, limitations and... Conclusion References

 
Occasional difficult laryngoscopic intubations have led to the development of many alternative intubation techniques. Neck transillumination using a lightwand has been shown to be effective for decades. A newly developed lightwand (Trachlight^TM) incorporates many design modifications to facilitate both oral and nasal intubation. The device should be avoided in patients with tumours, infections, trauma or foreign bodies in the upper airways. Undoubtedly, successful TL intubation depends on the operator's experience and skill, as well the preparation of the patient and the device. As with any intubation technique, regular use of and practice with the lightwand will improve performance and may also reduce the likelihood of complications.

Revision received February 21, 2001. Accepted for publication November 1, 2000.

	References

TOP Abstract Introduction Developments leading to the... Description of the TL Intubation technique with the... Oral intubation Nasal intubation Clinical applications Associated techniques Difficulties, limitations and... Conclusion References

 
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4 Hung OR, Pytka S, Morris, I et al. Clinical trial of a new lightwand device (Trachlight) to intubate the trachea. Anesthesiology 1995; 83: 509–14.[Medline]

5 Hung OR, Al-Qatari M. Light-guided retrograde intubation. Can J Anaesth 1997; 44: 877–82.[Abstract/Free Full Text]

6 Nishiyama T, Matsukawa T, Hanaoka K. Safety of a new lightwand device (Trachlight^TM): temperature and histopathological study. Anesth Analg 1998; 87: 717–8.[Free Full Text]

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9 Iseki K, Murakawa M, Tase C, Otsuki M. Use of a modified lightwand for nasal intubation (Letter). Anesthesiology 1999; 90: 635.[Medline]

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14 Agrò F, Brimacombe J, Carassiti M, Morelli A, Giampalmo M, Cataldo R. Use of a lighted stylet for intubation via the laryngeal mask airway. Can J Anaesth 1998; 45: 556–60.[Abstract/Free Full Text]

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This Article Abstract Résumé de cet Article Full Text (PDF) Submit a scholarly reply Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Agrò, F. Articles by Gherardi, S. Search for Related Content PubMed PubMed Citation Articles by Agrò, F. Articles by Gherardi, S.