Topical anaesthesia of the airway using TrachlightTM and MADgic® atomizer in patients with predicted difficult tracheal intubation
Beijing, People's Republic of China
* E-mail: fruitxue{at}yahoo.com.cn
Editor—Although awake intubation is the technique most commonly chosen in cases with a difficult airway, gag, cough, and laryngospasm in response to intubation may be troublesome.1 The MADgic® atomizer (Wolfe Tory Medical Inc., Salt Lake City, UT, USA) is a new device for spraying topical anaesthetics in the laryngotracheal region, which provides atomized topical solution directly to the mucosa of the airway. The applicator portion can also be adapted to an individual patient's anatomy.2 However, use of MADgic® atomizer to spray local anaesthetics in an airway requires direct laryngoscopy which may not only result in oropharyngeal stimulus which the awake patient does not tolerate, but may not visualize the vocal cords in some situations.
The use of a lightwand for routine intubation, in experienced hands, has been shown quicker, to be reliable and better tolerated by the patient than traditional laryngoscopic technique.3 In addition, lightwand has also proven to be a very useful option in the case of a difficult or impossible laryngoscopic intubation for both anticipated and unanticipated situations.4 We have combined the TrachlightTM (Laerdal Medical Corporation, New York, USA) and MADgic® atomizer to provide topicalization of the pharynx, larynx, and trachea before awake orotracheal intubation.
After local ethics committee approval and written informed consent, we used this technique in 18 adult patients (ASA I, aged 18–59 yr) scheduled for elective plastic or maxillofacial surgery with general anaesthesia requiring orotracheal intubation. All patients were predicted to have a difficult intubation [13 had limited mouth opening (inter-incisor distance 15–22 mm), three were Mallampati grade 4, and two had micrognathia (thyromental distance of 5 cm or less)]. In these cases, the initial plan was to use the awake lightwand intubation after topical anaesthesia of airway.
The wand of TrachlightTM with the internal stylet is inserted into a lubricated elastic lactoprene tube (8 cm long and internal diameter of 5 mm) until its light bulb just protrudes beyond the distal end. The applicator portion of MADgic® atomizer is also inserted into the lactoprene tube until its distal end is at the level of the light bulb. To avoid the interference for the transillumination of soft tissues of the anterior neck, the applicator portion of the atomizer is always held under the wand. The unit is then bent to a 90° angle in the sagittal plane just at the proximal lactoprene tube in the ‘hockey stick’ configuration (Fig. 1) and the wand is attached to the handle.
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In the operating room, the patients were given fentanyl 1.5 µg kg–1 i.v. and a variable dose of midazolam (range 1–8 mg) to the desired level of sedation, with the patient calm, falling asleep if undisturbed, but still appropriately responding to verbal commands. The patient's head and neck were placed in a neutral position and the jaw elevated. The unit was passed in the midline until a bright, well-circumscribed circle of light was seen at the level of the hyoid, indicating that its tip is in the epiglottic vallecula.3 At this time, 1 ml of lidocaine 2% was sprayed using the atomizer. The fine left or right rotation of the unit was then done to obtain a bright glow in the lateral aspect of the larynx, indicating tip is in the piriform recess, and 2 ml of lidocaine 2% was sprayed in two aliquots onto the bilateral piriform recess. This procedure was repeated after 5 min. After completion of the supraglottic spray, the unit was again inserted until a central, clear, and bright transillumination was seen on the cricothyroid membrane, suggesting correct positioning of the unit's tip into the laryngeal inlet.3 At this time, 3 ml of lidocaine 2% was sprayed during inspiration to anaesthetize the laryngeal and tracheal area. After 5 min, tracheal intubation was attempted.
All patients tolerated insertion of the unit without any discomfort or gagging. The mean time required for the supraglottic spray (36 times in all) was 39.3 (9.8) s, with a range of 32–53 s. The unit was successfully guided into the laryngeal inlet at the first attempt in all patients. During the laryngeal and tracheal spray, slight or moderate cough occurred in all patients and resolved spontaneously. After completion of the final spray, the average visual analogue scores for pain, anxiety, and gagging that the patients reported were 7.8, 6.5 and 7.2, respectively (where 0, absolutely awful and 10, enjoyable). The time required for the laryngeal and tracheal spray was 29.5 (8.5) s, with a range of 23–37 s. The median dose of lidocaine was 2.7 mg kg–1, with a range of 2.3–3.2 mg kg–1. Tracheal intubation was successfully completed using a TrachlightTM at the first attempt in a mean time of 23.7 (8.2) s. The slight cough was observed in four patients during tracheal tube insertion.
Similar approaches have been attempted using an epidural catheter5 attached to a Surch-liteTM (Aaron Medical Industries, St Petersburg, FL, USA) and an infant feeding tube6 to a TrachlightTM-tracheal tube assembly. However, we believe that the MADgic® atomizer can provide more effective atomized topical solution to the airway mucosa. Unlike spray-as-you-go topical anaesthesia of the airway using a fibreoptic bronchoscope, this combined approach needs less preparation and is less affected by secretions or blood.7 8 Additionally, the lightwand can also be cleaned and sterilized readily.3 4 The previous studies also reported that the ‘spray-as-you-go’ technique did not give optimal topical anaesthesia for fibreoptic bronchoscopy.8
Our preliminary experience of 18 patients suggests that a combination of TrachlightTM and MADgic® atomizer can provide excellent topical anaesthesia of the airway for awake orotracheal intubation. The technique is easy to perform, well tolerated by the awake patient, and useful in difficult intubation.
References
1 Benumof JL. Management of the difficult adult airway: With special emphasis on the awake tracheal intubation. Anesthesiology (1991) 75:1087–110.[CrossRef][Web of Science][Medline]
2 Supbornsug K, Osborn IP. Topicalization of the airway using the glidescope. Anesth Analg (2004) 99:1263–4.
3 Davis L, Cook-Sather SD, Schreiner MS. Lighted stylet tracheal intubation: a review. Anesth Analg (2000) 90:745–56.
4 Agrò F, Hung OR, Cataldo R, Carassiti M, Gherardi S. Lightwand intubation using the Trachlight: a brief review of current knowledge. Can J Anesth (2001) 48:592–9.[Web of Science][Medline]
5 Higgins MS, Wherry TJ. Topical anesthesia of the airway using the lighted stylet [letter]. Anesthesiology (1993) 79:1148.[Web of Science][Medline]
6 Bhardwaj A, Kidwai SN, Verma V, Nabi N, Ahmad M, Khan RM. Continuous anesthetic insufflation and topical anesthesia of the airway using Trachlight in chronic facial burns. Anesth Analg (2006) 102:334.
7 Williams KA, Barker GL, Harwood RJ, Woodall NM. Combined nebulization and spray-as-you-go topical local anaesthesia of the airway. Br J Anaesth (2005) 95:549–53.
8 Graham DR, Hay JG, Clague J, Nisar M, Earis JE. Comparison of three different methods used to achieve local anesthesia for fiberoptic bronchoscopy. Chest (1992) 102:704–7.[CrossRef][Web of Science][Medline]
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