Flexible fiber CO2 laser ablation of subglottic and tracheal stenosis

Abstract

Acquired subglottic and tracheal stenosis is a challenging problem with many treatment options, including tracheostomy, endoscopic, and open surgical techniques. Treatment choice depends on the length, location, degree and quality of stenosis, cartilage integrity, and medical comorbidities. Although the main objective in the management of subglottic and tracheal stenosis is to provide a patent airway, other important secondary goals include avoidance of tracheotomy or early decannulation, and maintaining an adequate voice. Endoscopic laser ablation techniques have been described, including the neodymium-doped yttrium aluminum garnet (Nd:YAG) and microscope-mounted CO2 laser.1-7 The development of a flexible fiber CO2 laser delivery system allows for CO2 laser ablation of airway stenosis through a flexible bronchoscope. We present our experience with the CO2 laser via flexible bronchoscopy in two patients who were successfully managed with topical anesthesia and did not require tracheotomy. This retrospective review of two adult patients who underwent flexible laser bronchoscopy was conducted following approval from the institutional review board. Clinical histories, preoperative radiographic imaging, intraoperative, and postoperative photographs of the stenoses were obtained. The Omniguide CO2 laser (Omniguide, Inc., Cambridge, MA) flexible fiber delivery system and Olympus video bronchoscope (Olympus America, Center Valley, PA) was used for this procedure. The procedure is performed in the operating room with emergency tracheostomy and rigid bronchoscopy equipment available. The patient is seated upright on the operating table with supplemental oxygen administered through the mouth. The nasal cavity is decongested and anesthetized with a 1:1 mixture of 0.05% oxymetazoline and 4% lidocaine applied on cottonoid pledgets. The oropharynx is topically anesthetized and 8 mg of dexamethasone is given intravenously. A superior laryngeal nerve block may also be performed. Intravenous sedation may be used judiciously. The flexible bronchoscope is then passed via the nasal cavity to the level of the epiglottis; this area is then topically anesthetized with 2 mL of 4% lidocaine via the port on the bronchoscope. The bronchoscope is advanced, and the glottis and subglottic areas are similarly anesthetized. The exact location, length, and characteristics of the stenosis are quickly studied, and photographs of the stenotic segment are obtained. Passing the bronchoscope through the stenosis should be avoided to prevent complete airway obstruction. The procedure is continued once the presence of a thin stenotic segment is confirmed. Standard laser safety protocols are followed. The flexible laser fiber is advanced through the instrument port of the bronchoscope until the distal tip of the fiber is just visible through the bronchoscope. The laser in pulse mode at a power between 5 and 10 watts is used to vaporize two or three wedges of the stenosis with intervening intact mucosa to avoid circumferential denuding of the mucosa. Once adequate vaporization has been achieved, photographs are again taken. Immediate and progressive improvement in breathing is experienced by the patient during the procedure. The patient is then escorted to the postanesthesia care unit for monitoring. Each patient is admitted overnight and receives two additional doses of dexamethasone 8 mg every eight hours postoperatively. A 56-year-old female with a past medical history of congestive heart failure, diabetes mellitus, chronic obstructive pulmonary disease, and a history of several intubations, presented with biphasic stridor. Pulmonary function testing noted a decreased FEV1/FVC ratio of 66%, suggestive of upper airway obstruction. Physical examination revealed a patient with moderate biphasic stridor and mild respiratory distress at rest. Head and neck examination was otherwise normal. Flexible laryngoscopy revealed a thin-appearing, high-grade subglottic stenosis. Computed tomography (CT) of the neck revealed a thin subglottic stenosis (Fig. 1A). Flexible bronchoscopy confirmed a thin 70% circumferential stenosis confined to the subglottis (Fig. 1B). The patient underwent the described surgical technique (Fig. 1C). She had complete resolution of her symptoms at her 6 month follow-up visit. There was no audible stridor and voice quality was normal. Fiberoptic laryngoscopy confirmed a patent subglottic airway with mild residual stenosis (Fig. 1D). At 9 months follow-up, the patient continued to be asymptomatic. (A) Sagittal CT image showing thin subglottic stenosis (arrow). (B) Preoperative image showing area of subglottic stenosis. (C) Intraoperative view demonstrating laser ablation at the 11 to 1 o'clock, 4 to 5 o'clock, and 6 to 7 o'clock positions was performed. (D) Laryngoscopy 6 months postoperatively demonstrating mild residual stenosis. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] A 56-year-old female with a history of diabetes mellitus and obstructive sleep apnea presented with worsening dyspnea for approximately 1 year. She had a history of intubation 3 years prior to presentation for spine surgery. Physical examination showed an overweight female with moderate inspiratory stridor and mild hoarseness, but no distress at rest. Relative macroglossia was noted, and the remainder of her head and neck examination was normal. Fiberoptic laryngoscopy revealed a nonobstructive hemorrhagic polyp on the superior surface of the right true vocal fold. The subglottis could not be well seen. Workup for autoimmune disease was negative. Preoperative CT scan of the neck suggested a thin stenosis at the inferior border of the cricoid cartilage (Fig. 2A). A thin 70% stenosis was confirmed by flexible bronchoscopy (Fig. 2B). She underwent laser ablation using the described surgical technique (Fig. 2C). She had significant improvement in her symptoms, although the procedure was somewhat limited by the patient's cough and gag reflex. Planned repeat bronchoscopy was performed 2 weeks later, and she underwent additional laser ablation (Fig. 2D) with further symptomatic improvement. At 5 months follow-up, the patient had resolution of her dyspnea. On examination, there was no audible stridor and there was mild hoarseness. Fiberoptic laryngoscopy showed an unchanged hemorrhagic polyp, however the subglottis could not be well seen. (A) Coronal CT image showing thin stenosis at the inferior border of the cricoid cartilage (arrow). (B) Preoperative image showing area of subglottic stenosis (NB: preexisting hemorrhagic polyp of right true vocal fold). (C) Intraoperative view during first procedure where laser ablation at the 4 to 6 o'clock and 9 to 12 o'clock positions was performed. (D) Intraoperative view during the second procedure where laser ablation at the 12 to 2 o'clock and 9 o'clock positions was performed. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] Subglottic and upper tracheal stenosis has been conventionally treated with open surgical procedures, including segmental resection of tracheal stenosis with primary anastomosis, or laryngotracheal reconstruction with cartilage grafting when the subglottis is involved. Endoscopic laser ablation of stenosis, with or without dilation and mitomycin-C, through a laryngoscope and microscope-mounted CO2 laser has also been used successfully in selected cases. However, use of the microscope-mounted CO2 laser requires general anesthesia with either tracheostomy or Venturi-jet ventilation, both of which have drawbacks. Use of a flexible fiber laser delivery system via flexible fiberoptic bronchoscopy circumvents the need for general anesthesia. The patient is awake and breathing spontaneously, minimizing the risk for catastrophic airway obstruction after induction of general anesthesia. This technique can be used in patients with medical contraindications to general anesthesia as well. Although success has been demonstrated using the Nd:YAG laser,1, 2 which can be delivered via a flexible fiber, the absorption characteristics and potential for deep thermal injury makes this choice of laser less than optimal. The CO2 laser absorption characteristics result in only superficial thermal injury, and are much better suited for this application, but had not been available in a flexible fiber delivery system. Patient selection is critical for the success of this procedure. Both patients presented had stenoses that were several millimeters thick at their most central aspect. This thin tissue vaporizes quickly and easily when the laser is applied, leading to rapid improvement in symptoms during the procedure. The stenosis in both patients was noted to become thicker more peripherally, and is somewhat more difficult to vaporize. This procedure may be applicable to patients with thicker stenoses. However, it would seem wise to limit this procedure to patients with stenoses less than 1 cm in length in the subglottis and upper trachea. In addition, patients with an associated cartilage deformity or loss should not undergo this procedure. In this case series, the Omniguide CO2 laser was used in these two patients because the characteristics of their stenoses appeared to be well suited to this technique. The procedure was very well tolerated, and the clinical improvement was dramatic and immediate. Although the length of follow up was relatively short, the immediate improvement was maintained throughout the follow-up period. Long-term follow-up will be necessary to confirm the early success of this procedure. Patients with longer segments of stenosis and/or cartilage deformity require other surgical techniques. Further, patients in severe respiratory distress may not tolerate the procedure well, and may require tracheostomy first. Another drawback to this approach, especially with longer segments of stenosis, is that topical mitomycin-C cannot be used and dilation cannot be performed in an awake patient with an unprotected airway. Flexible fiber CO2 laser ablation of subglottic and tracheal stenosis via flexible bronchoscopy with topical anesthesia can be used successfully in patients with thin segments of stenosis, less than 1 cm in length, without tracheostomy or general anesthesia. Although our patients were followed 5 to 9 months postoperatively without any recurrent symptoms, longer follow-up is needed to confirm the initial success of flexible fiber CO2 laser ablation of subglottic and tracheal stenosis.