Abstract
The Trachway is a new device which provides better glottic view than conventional direct laryngoscopy during tracheal intubation. This intubating stylet consists of a camera on the distal tip of the style, with a monitor attached to the rechargeable handle, so that it can overcome the difficulty of limited neck motion and mouth opening in tracheal intubation. We present here a 54-year-old man with ankylosing spondylitis, scheduled to undergo total hip replacement. Pre-operative airway assessment revealed a recognized difficult airway. The Trachway was successfully used for oral tracheal intubation at the first attempt. The Trachway can be an alternative choice for intubation in ankylosing spondylitis patients.
Keywords
intratracheal; intubation; laryngoscopy; laryngoscopes; Trachway;
1. Introduction
Video-assisted intubating devices have been recently introduced into clinical practice, particularly for difficult airway intubation. The Trachway intubating stylet (Biotronic Instrument Enterprise Ltd., Tai-Chung, Taiwan) is a new airway device with a rigid but malleable intubating stylet.1 There is a light source and camera at the distal end of the style. The proximal end of the stylet can be plugged into a rechargeable handle (Fig. 1).2 The laryngeal inlet and vocal cords can be visualized on the monitor attached to the handle. It is encased in the tracheal tube before intubation and the tracheal tube can be slid into the trachea through visualization of the glottis and vocal cords on the monitor. The use of the Trachway for airway management can overcome the problems of limited neck motion and difficult airway.3
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The patient, with ankylosing spondylitis (AS), was a case of a potential difficult airway, because the disease involves the cervical spine and the temporomandibular joint. Neck extension can cause vertebrobasilar insufficiency as a result of encroachment of bone on the vertebral artery. Therefore, intubation under direct laryngoscopy with excessive neck motion could be associated with a significant risk of neurological injury in patients with cervical kyphosis.3 Awake fiber optic intubation is the safest option for these patients, especially when the vocal cords can hardly be visualized under direct laryngoscopy or in patients with severe chin or chest deformity. However, it is quite uncomfortable for patients to undergo fiber optic intubation when awake. Previous studies reported successful intubation with McGrath (Aircraft Medical Limited, Edinburgh, UK) or Glidescope (Verathon Medical B.V. Boerhaaveweg, Ijsselstein, The Netherlands) in AS patients.4, 5, 6 However, there is still an instance of failed intubation with Glidescope even in a patient under curarization.7
We present here an AS case with limited mouth opening, whose trachea was successfully intubated orally with a Trachway intubating stylet under anesthesia.
2. Case report
A 54-year-old man (65 kg), suffering from AS, was admitted to our hospital due to persistent left rump pain for some 8 years, for which left hip osteoarthritis was responsible; he was scheduled to undergo a total hip replacement.
Preoperative airway assessment showed limited mouth opening with an interincisor distance of only 3 cm, but without instable teeth. Although the thyromental distance was only 8 cm, the pharyngeal appearance was Mallampati class IV. Due to AS, his neck motion was limited, whether in flexion or extension. Both general and regional anesthesia are suitable for total hip replacement, but regional anesthesia is technically difficult for an AS patient, due to ossification of joints and entheses of the axial skeleton (also known as bamboo spine), the undertaking of which may render the patient to run the risk of complications. Therefore, general anesthesia with endotracheal intubation was planned.
Awake fiberoptic intubation would have been the safest choice for this AS patient with difficult airway. However, the patient refused to receive awake intubation due to previous uncomfortable experiences. Thus we chose Trachway intubation under general anesthesia. The intubation procedure was discussed, and the patient understood and agreed.
With his written informed consent, Trachway intubation was undertaken. He was placed in a head-elevating position with his head resting on a large and thick pillow, because of his curved cervical spine, and the table was adjusted to suit the modified Trendelenburg position for intubation. Following establishment of basic monitoring, trans-tracheal block with 2% lidocaine (100 mg) was performed, and he was then pre-oxygenized with a face mask. Anesthesia was induced by intravenous fentanyl 100 μg (1.54 μg/kg), thiamylal 300 mg (4.6 mg/kg), and inhalation of sevoflurane (5%) in oxygen. Once adequate ventilation and an appropriate depth of anesthesia was confirmed, Trachway intubation, with an internal 7.5 mm diameter endotracheal tube was performed. We inserted the Trachway stylet along the midline of the tongue towards the pharynx. The oropharyngeal structure was visualized on the monitor and the epiglottis was seen while we advanced the intubating Trachway stylet along the midline of the tongue. The tip of the stylet was moved laterally to cross the epiglottis, and the vocal cords were seen (Fig. 2). After the stylet had advanced into the trachea, just a short length below the vocal cords, the tracheal tube was slid into the trachea to a proper depth. The Trachway stylet was withdrawn with the tracheal tube holding still. The intubation was smoothly accomplished at the first attempt without neck mobilization or laryngeal manipulation.
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3. Discussion
Management of difficult airways is laborious, but crucial for anesthesiologists. A full evaluation of the airway should be carried out preoperatively. The patient’s medical history or prior records, that might contain something relative to the condition of the airway, should be reviewed.8 A thorough physical examination should be performed, particularly pertaining to the airway condition. It should include evaluation of the interincisor distance, thyromental distance, visibility of the uvula (by Mallampati classification), and range of motion of the head and neck.
Patients with severe AS are frequently difficult or impossible to intubate under conventional laryngoscopy, due to limited mouth opening and cervical spine rigidity. Awake fiber optic intubation is always the safest choice. In some operative procedures performed in the supine or lateral position, general anesthesia could be conducted successfully via conveyance of a laryngeal mask airway (LMA) (classical or intubating), should the AS patients have patent airways and normal oral or nasal apertures.9 However, in our case, the LMA was not considered a suitable conveyer due to the patient’s limited mouth opening and the difficult insertion of the LMA into his mouth.
Fiber optic bronchoscopy may also be applied for tracheal intubation in AS patients under deep anesthesia without curarization. However, while searching the glottis, it may be necessary to lift the patient’s jaw to facilitate intubation. Therefore, it is difficult to perform such intubation without the aid of an assistant. Besides, fiber optic intubation may require higher skills and longer learning and practice times. By contrast, the Trachway technique is easier to learn and can be used by a single operator.
There may be some risk of damaging the upper teeth during the advancement of the rigid stylet of Trachway into the trachea. However, we can avoid this risk by moving the stylet laterally while advancing it into the trachea, in order to prevent damage to unstable teeth.
The Trachway intubating stylet is a convenient device for tracheal intubation. It is an intubating stylet just like a lightwand. Therefore, when we use the Trachway for intubation, it should be advanced along the midline of the tongue, like using a lightwand. The view of the glottis can easily be seen on the monitor, even in patients with a difficult airway. As soon as the epiglottis is seen, the stylet can be passed through it and then the vocal cords will come into view. The endotracheal tube can be slid into the trachea accordingly. There is no need to move the patient’s head or neck to facilitate intubation and it can be used in patients with limited mouth opening. Previous studies compared the efficacy of the Trachway intubating stylet with that of the Macintosh Laryngoscope in difficult airway scenarios, including cervical spine immobilization; they found that Trachway could serve intubation in a shorter time as compared with the Macintosh laryngoscope, and thus may act as an alternative device for intubation.
This article described the clinical use of the Trachway intubating stylet in a recognized difficult airway, to raise awareness of this novel device. The Trachway intubating stylet has the following potentials: firstly, although it has an intubation stylet just like a lightwand, it has an external color monitor to view the oral and pharyngolaryngeal structures during the intubation process. Thus, the Trachway intubating stylet could avoid a blind and potentially traumatic airway manipulation. Secondly, the Trachway intubating stylet could be used in patients with a limited mouth opening, such as with an interincisor gap distance of less than 4 cm. In conditions where video-laryngoscopes such as the GlideScope and Pentax Airway scope are not serviceable for airway management, the Trachway intubating stylet can still be used as a last resort as an intubating device.
The limitations of the Trachway should also be addressed. Firstly, it can not be used for nasal intubation, due to its original design. Secondly, only tracheal tubes of larger bores (internal diameter of 6.0–8.0 mm) can load the intubation stylet and it is not suitable for pediatric intubation, at present.