Abstract
The Airway Scope® (AWS) provides better glottic view than the conventional direct laryngoscopy in tracheal intubation. With it, the endotracheal tube can be more easily inserted into the tracheal lumen easily. We hereby presented a 24-year-old ankylosing spondylitis (AS) patient wearing a halo vest who was successfully intubated for undergoing cervical spine surgery involving C1 and C2 under general anesthesia. Pre-operative airway assessment revealed that he was a case of difficult intubation. An AWS was used for oral tracheal intubation which was achieved smoothly in the first attempt. AWS can be an alternative device for airway management in a patient wearing halo vest.
Keywords
orthotic devices: halo vest; intubation, intratracheal; laryngoscopes: video-assisted; spondylitis, ankylosing;
1. Introduction
The Airway Scope® (AWS; PENTAX, Tokyo, Japan)1 is a newly introduced rigid video laryngoscope for airway management. The device consists of an ergonomically designed handle encompassing an LCD (Liquid crystal display) color screen, a battery compartment, a video-out port, and a locking connecting ring to attach a Lexan plastic disposable blade that mounts over the optical image bundle. Fascinatingly, the AWS has two channels alongside the laryngoscope blade. The main channel is for lodgement of an endotracheal tube, whence it can be guided directly into the trachea. The sub-channel, is for accepting a thin catheter, which serves as a route for topical anesthesia of the larynx and for toilet suction.2 The AWS permits a nonlinear sight view of the airway.3 This new device for airway management breaks through the limitation of neck motion, in a patient wearing halo vest apparatus.
2. Case report
A 24-year-old man (height 170 cm; weight 67 kg) with history of AS for 5 years was admitted to our hospital presenting progressive bilateral weakness and numbness of the upper limbs for recent 10 days. Halo vest was worn prior to the surgical intervention. He was scheduled for C1 and C2 decompression and fusion. Preoperative airway assessment revealed a free mouth opening (>4 cm) and intact upper and lower dentition without overbite. The thyromental distance was over 6 cm. The Mallampati score as rated was class III and the motion of his neck, including flexion and extension, was fixed due to wearing halo vest. General anesthesia with tracheal intubation was required for the surgery. In spite of difficulty, tracheal intubation with conventional direct laryngoscope or awake fiberoptic intubation could be tried.
Awake fiberoptic intubation was our primary contemplation but the patient refused and requested that he should be intubated under general anesthesia. In compliance with his request and obtaining his written informed consent, we decided to carry out the intubation with AWS under general anesthesia.
The patient was placed in the head-up tile position with his head and neck on a line with the halo vest. Following establishment of routine monitoring and pre-oxygenation by face mask (Fig. 1), anesthesia was induced and maintained by inhalational anesthesia with sevoflurane (3–5%) in oxygen without any intravenous anesthetics. Once adequate mask ventilation and depth of anesthesia were confirmed, rocuronium (1 mg/kg) was administered. Ninety seconds after the rocuronium administration, tracheal intubation with the AWS, pre-inserted with an endotracheal tube (standard, curved tube, 7.5 mm ID) in its main channel was carried out. The pharyngolaryngeal structures were anatomically visualized on the monitor as the scope advanced along the dorsum of the tongue. The tip of the AWS was placed posteriorly to the epiglottis, and a gentle lifting force was then applied to elevate the epiglottis. The position of the AWS was adjusted to optimize the glottis view. The tube was then advanced to slide into the trachea under vision until the crossed-marker was at the level of the vocal cords (Fig. 2). Following the cuff of the endotracheal tube passing the vocal cords, the tube was detached away from the channel. Further advancement of the endotracheal tube to a proper depth was done and then the AWS was pulled back along the tongue. The intubation process smoothly succeeded in the first attempt without the need of neck mobilization and external laryngeal manipulation.
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3. Discussion
Airway management and tracheal intubation in patients wearing halo vest can be difficult and challenging; awake fiberoptic intubation is ideal and safe to secure airway in these patients because of no need of neck mobilization. However, it is an uncomfortable procedure, and thus many patients may refuse and resist the technique. Fiberoptic intubation with laryngeal mask airway under general anesthesia in patients with halo vest has been reported.4 The idea is novel but this method requires skillful technique of experienced hands and thus its application is limited to the operating room. Some video laryngoscopes have been developed for providing better glottic views to facilitate tracheal intubation in patients with difficult airways. Certain studies have demonstrated that nasal tracheal intubation with the GlideScope® in patients with suspected difficult airways, such as in AS is rapid and successful.5, 6 Nasal trauma often follows with nasal intubation. The operators also need to manipulate the tip of the endotracheal tube into the tracheal lumen, and occasionally external compression of the cricoid cartilage is necessary.
The AWS is a newly developed device and is on the market since 2007. In most patients, the AWS provides an improved view of the larynx compared with the Macintosh laryngoscope.7 Since it provides a better view of the glottis, it is extremely useful when airway management conditions are difficult. The AWS not only improves the laryngeal view, but with its tube guide it also facilitates rapid, easy and reliable tracheal intubation under vision. With portability and excellent technicality it processes tremendous potential in difficult airway management in near future. In all video laryngoscopies the presence of excessive secretions and blood may hinder visual field and render intubation difficult. Its sub-channel for lodgement of a thinner suction tube may be helpful for their removal but further evidence is required for a solid proof.
This case report is the first article describing the usage of the AWS for tracheal intubation in a patient wearing halo vest for general anesthesia. The AWS is user-friendly and its use is easy to learn even in non-anesthetic operators. It provides an alternative for tracheal intubation in patients with halo vest. For patients who accept awake fiberopitc intubation, there is no significant benefit gained in its use for intubation under general anesthesia. This alternative method may be suggested for patients who refuse or cannot tolerate awake intubation.