According to an extensive review of the relevant literature worldwide, patients with large vocal cord polyps of this size are relatively rare. Consequently, we conducted a comprehensive evaluation of the patient’s airway. The patient’s history of difficult tracheal intubation, body mass index, anatomical measurements, and preoperative electronic laryngoscopy results all suggested a difficult airway. The 2022 American Society of Anesthesiologists (ASA) Practice Guidelines for Management of the Difficult Airway recommend awake intubation be performed if the patient is suspected to have a difficult intubation and difficult facemask ventilation is anticipated [
5]. If intubation is performed after the induction of general anesthesia, intubation failure may lead to displacement of the vocal cord mass, bleeding, and glottic edema [
2]. Therefore, awake intubation was performed in this case to avoid difficult facemask ventilation owing to exacerbated respiratory obstruction. The ASA Difficult Airway Guidelines mention that the literature evaluating the optimal sequence of equipment to use during intubation for anticipated difficult airways and the most effective equipment to be attempted first after failed intubation is limited [
5]. In the past, the primary choice for awake intubation in patients with anticipated difficult airways was flexible fiberoptics [
6]. However, developing proficiency with fiberoptic intubation requires a rigorous learning process and the technique typically requires a substantial amount of time to perform [
7]. With advancements in visualization technology, various types of video laryngoscopes and video stylets are now widely used to manage difficult airways. Compared with conventional direct laryngoscopy, video laryngoscopy has a higher intubation success rate, shorter intubation time, and fewer intubation-related complications. However, video laryngoscopy may not be appropriate for patients with limited mouth opening capacity or cervical spinal injuries. A recent study comparing the efficacy of flexible videoscopes, video laryngoscopes, and video stylets for orotracheal intubation under general anesthesia in patients with difficult airways found that video stylets and flexible videoscopes yielded higher rates of successful first-attempt intubations and better glottic exposure than video laryngoscopes [
8]. Additionally, the use of video stylets for endotracheal intubation resulted in a significant reduction in intubation time compared with both the video laryngoscope and flexible videoscope. Therefore, we recommend the use of a video stylet as the first choice for difficult airway management. Another previous study found that in patients undergoing oral and maxillofacial surgeries, the required procedural time was reduced when nasotracheal intubation was performed using a Disposcope endoscope (which is a type of video stylet) compared with fiberoptic bronchoscopy [
9]. Prolonged awake intubation may increase the risk of loss of airway patency in patients owing to the use of sedative and analgesic drugs. In addition, prolonged intubation may increase patient discomfort and the stress experienced by the anesthesiologist [
7]. Although the monitors of most video stylets are connected to the stylet, the Disposcope endoscope transmits images wirelessly to the portable screen. Thus, the screen does not move as a result of maneuvering and advancing the tube during the procedure, facilitating the anesthesiologist’s capacity to observe and manipulate effectively. However, the Disposcope endoscope does have some limitations, such as the lack of a working channel for suctioning secretions, which may compromise visualization if considerable secretions are present. This limitation can be overcome by positioning the lens at the Murphy’s orifice of the tracheal tube without moving the lens over the tip and by improving the operational skill [
8]. Although Disposcope endoscopes have recently been used for awake nasotracheal intubation [
10], to date, reports on the use of Disposcope endoscope for awake orotracheal intubation are limited.
For this case, the epidural catheter was tightly attached to the Disposcope endoscope. As the special shape of the endoscope is consistent with that of the airway, the tongue base, epiglottis, and glottis can be fully anesthetized. Adequate topical anesthesia of the airway can improve the patient’s tolerance to intubation and minimize the stress response. For this case, we chose an endotracheal tube with an inner diameter of 5.5 mm given the large size of the polyp and our concern that a large tube would not pass smoothly through the glottis or would cause the polyp to fall off. In clinical practice, we have observed that passing the Disposcope endoscope, which is tightly attached to the epidural catheter, through the interior of an endotracheal tube with an inner diameter of 5.5 mm can be difficult, even when it is lubricated with liquid paraffin. In this case, the Disposcope endoscope had to be used twice during intubation: first during adequate topical anesthesia of the airway and again during tracheal intubation. If the inner diameter of the tracheal tube is larger than 5.5 mm, a Disposcope endoscope can be used to simultaneously complete topical anesthesia of the airway and tracheal intubation (
Figs. 4A and
B). To the best of our knowledge, this is the first study to report the use of a Disposcope endoscope to assist in topical anesthesia of the airway. In the future, we aim to develop removable, disposable consumables mounted on video stylets for topical airway anesthesia.
In conclusion, we suggest that awake orotracheal intubation with the Disposcope endoscope can be a useful option for anticipated difficult intubation and difficult facemask ventilation. Future studies should focus on exploring the value of the Disposcope endoscope in various clinical settings.