The distal segment is brought over to the proximal segment and sutured together; the reconstructed segment is sutured to the thyroid cartilage.
Microscopic examination of a section taken at the suture line between the proximal and the distal segments reveals fibrosis between the 2 ends of cartilage and continuity of the respiratory epithelium (hematoxylin-eosin, original magnification ×20).
A specimen of a vertically opened larynx and the reconstructed part of the trachea, showing good healing at the suture line without scar or granulation tissue formation.
Abdelkafy WM, El Atriby MN, Iskandar NM, Mattox DE, Mansour KA. Slide Tracheoplasty Applied to Acquired Subglottic and Upper Tracheal StenosisAn Experimental Study in a Canine Model. Arch Otolaryngol Head Neck Surg. 2007;133(4):327-330. doi:10.1001/archotol.133.4.327
Copyright 2007 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.2007
To assess the applicability and complications of slide tracheoplasty in the management of subglottic and upper tracheal stenosis in experimental animals.
Subglottic stenosis was induced in 10 dogs by cauterizing the subglottic area and the upper 3 to 4 cm of the trachea. After 21 days, the severity of stenosis ranged from 30% to 60%. The subglottic area was reconstruction with slide tracheoplasty, and the results were evaluated at 4, 12, and 24 weeks postoperatively.
Ten mongrel dogs (Canis familiaris) were included in the study, each weighing between 12 and 17 kg.
Main Outcome Measure
Patency of the reconstructed segment.
Follow-up examination revealed no airway obstruction in any animal. Examination of the reconstructed segment revealed good healing without granulation tissue and a patent endotracheal lumen in all cases. Histopathological examination of sections taken at the suture line confirmed complete healing without granulation tissue.
Slide tracheoplasty can be applied successfully to the subglottic area. It offers many advantages in tracheal reconstruction and can be used for the management of acquired subglottic stenosis. The vascularized tracheal cartilage heals without granulation tissue often seen after cartilage interposition grafts. Furthermore, this technique reduces the need for tracheal and laryngeal mobilization for the treatment of longer areas of stenosis.
Subglottic stenosis is a fibroproliferative disorder that may affect persons of all ages owing to a variety of causes, including prolonged endotracheal intubation, gastroesophageal reflux, autoimmune disorders, and iatrogenic disorders.1 Management of subglottic stenosis constitutes a challenge because of the high incidence of restenosis. Conservative measures include dilatation, stents, steroid injection, cryotherapy, and laser therapy. Open surgical procedures include anterior and posterior cricoid split, placement of stents, mucosal and cutaneous grafts, and free grafts of cartilage, pedicled hyoid, and cutaneous flaps variously supported with cartilage. Success is limited with these procedures because of restenosis and development of granulation tissue that requires repeated endoscopic management.2
Cricotracheal resection removes the stenotic area with good healing, especially with tension-free approximation of tracheal ends.3 However, a tension-free closure is difficult when the resection is more than 3 cm. Many measures are available to mobilize the proximal and distal tracheal segments to reduce tension on the anastomosis including cervical flexion, hilar dissection, intrapericardial freeing, and right main stem bronchus transposition4- 11; however, the maneuvers are not without morbidity including injury to the superior laryngeal nerve and vessels, dysphagia, pneumomediastinum, and mediastinal vascular and visceral injuries.
Tsang et al12 first described slide tracheoplasty in 1989 as a new surgical technique for congenital funnel shape tracheal stenosis. The trachea is exposed, circumferentially mobilized, and divided transversely at the midpoint of its narrowed segment. The distal segment of the tracheal stricture is divided longitudinally along its posterior wall, and the proximal end is divided longitudinally along its anterior border. The 2 segments are advanced over each other and sutured together. The slide tracheoplasty results in doubling the circumference of the trachea and a 4-fold increase in the cross-sectional area of the airway. The stenotic segment is shortened by one half of its length rather than by its full length, which would be the case with resection and end-to-end anastomosis. Ventilation during this procedure is performed through an endotracheal tube with intermittent ventilation.
In 1994, Grillo13 published his series describing the same technique with minor modifications in congenital tracheal stenosis. Four patients (aged 3 months, 3.5 years, and 19 years [2 patients]) were treated for stenosis of 36% to 83% of tracheal length. The approach was with either cervical or partial sternotomy. Cardiopulmonary bypass was not necessary. Blood supply was not impaired; healing was excellent with minimal complications.
Subglottic stenosis longer than 3 cm is difficult to resect without the need for 1 or more release procedures. These release procedures can be avoided by using slide tracheoplasty. In slide tracheoplasty native vascularized tracheal cartilage is used for reconstruction, which may result in better healing without granulation tissue formation obstructing the tracheal lumen.14
This study was performed to assess the application of slide tracheoplasty in acquired long-segment subglottic and tracheal stenosis using an experimental canine model, with the hypothesis that slide tracheoplasty, previously used for congenital tracheal stenosis, can be applied to acquired subglottic and upper tracheal stenosis.
This study was approved by the Suez Canal University Research Committee (Ismailia, Egypt) and was conducted using the animal care facilities in the Faculty of Veterinary Medicine. The animals received humane care in compliance with the principles of laboratory animal care. Ten mongrel dogs (Canis familiaris) were included in the study, each weighing between 12 and 17 kg.
Stenosis was induced using a successfully proven technique for induction of subglottic stenosis described by Eliasher et al15 in 2000. Each dog was anesthetized with intramuscular ketamine hydrochloride (20 mg/kg) and intramuscular xylazine hydrochloride and then placed in the back dorsal position. Its mouth was kept open with a bite blocker, and the tongue extended and secured with a strip of gauze tied to the bite blocker. The larynx was visualized using a standard operating laryngoscope of appropriate size. The larynx was sprayed with topical anesthetic spray (2% lidocaine hydrochloride spray). A long insulated suction tip was connected to a standard Bovie electrocautery unit and operated at 40 power units. The mucosa and the underlying cartilage of the subglottic and upper trachea (starting from the upper border of the cricoid cartilage) were injured with 5 seconds of exposure with the same power at 4 equally spaced points at the 12-, 3-, 6-, and 9-o’clock positions. The length of the segment injured ranged from 4 to 6 cm. After injury, the dogs were observed for any sign of airway obstruction. The amount of resulting subglottic and tracheal stenosis was assessed at 21 days, and slide tracheoplasty was performed. Immediate surgery was planned for any dog that developed signs of acute airway obstruction; however, this did not occur.
The procedure was performed using general anesthesia with thiopental (3 mg/kg) for induction, and administration of the dose was repeated for the duration of the operation. The airway was secured using an endotracheal tube placed through an H-shaped tracheotomy incision distal to the stricture.
A vertical midline neck incision was made, followed by dissection of the superficial fascia and splitting of the strap muscles. The thyroid isthmus was divided for exposure of the larynx and the cervical trachea. Circumferential dissection of the trachea was performed with an additional dissection 4 to 5 cm distal to the site of stenosis.
The stenotic segment was measured by means of preoperative bronchoscopic evaluation and divided at midpoint. The proximal half, including the cricoid cartilage, was split along its anterior wall (a modification from the original slide tracheoplasty), and the cricothyroid membrane was divided separating the anterior half of the cricoid cartilage from the thyroid cartilage, while the distal segment was split along its posterior wall. The right angle corners where the vertical incisions meet the transverse incision were trimmed. The 2 ends were overlapped on each other and sutured using interrupted 4-0 Vicryl (Ethicon Inc, Piscataway, NJ), followed by suturing of the reconstructed segment to the thyroid cartilage (Figure 1). The tracheotomy tube was removed at the end of the procedure.
Postoperative pain was managed with diclofenac sodium intramuscularly (25 mg), once daily, and all dogs were given cefoperazone, 500 mg intramuscularly perioperative, for infection prophylaxis.
After reconstruction of the stenotic segment using slide tracheoplasty, the dogs were humanely killed using intravenous pentobarbital sodium (75 mg/kg) after variable postoperative periods, and the larynx with the reconstructed part of the trachea were removed for gross and histopathological examination. The dogs were divided into the following 3 groups: group 1 comprised 3 dogs killed 4 weeks after reconstruction; group 2, 3 dogs killed 12 weeks; and group 3, 4 dogs killed after 24 weeks.
During the period between reconstruction and killing, the dogs were observed for any signs of respiratory tract obstruction and surgical wound infection. Changes in barking were used as an indicator of the voice after reconstruction. Gross examination of the specimens was done to assess the diameter of the tracheal lumen and the presence of granulation tissue in the reconstructed part of the trachea. Histopathological examination of the suture line was performed to evaluate healing, inflammation, and granulation tissue after reconstruction.
After induction of subglottic stenosis, the degree of stenosis varied from 30% to 60% (grades 1 and 2 stenosis, Mayer-Cotton classification of subglottic stenosis).16 The acquired stenosis was circumferential along the injured segment.
There were no signs of respiratory tract obstruction that required emergency intervention in the postinduction period, but all of the dogs developed a weakened bark and had slightly reduced food intake. None of the dogs developed any sign of respiratory tract obstruction after tracheal reconstruction. Tracheotomy was not needed in any of the cases before or after reconstruction. Bilateral vocal cord mobility was confirmed by means of laryngoscopic evaluation after reconstruction. Barking returned to normal or near normal after the third postoperative week.
One dog developed surgical wound infection at postoperative day 4, which was treated with antibiotics for 1 week without the need for surgical drainage.
After reconstruction, the cross-sectional diameter of the stenotic segment was nearly doubled in all of the dogs (Table). In group 1 (killed after 4 weeks), the lumen of the trachea was patent and mucosal healing was obvious; no granulation tissue was detected inside the lumen or at the suture line. Microscopic examination revealed mucosal healing.
In group 2 (killed after 12 weeks), the lumen was patent, no contractures or scarring were found in the trachea, no granulation tissue was found in the lumen or at the suture line, and no breakdowns were detected at the suture line. Microscopic examination revealed continuous respiratory epithelium over the suture line and fibrosis between the 2 ends of the cartilage (Figure 2).
In group 3 (killed after 24 weeks), microscopic examination revealed mature fibrosis detected between the 2 ends of the cartilage. Gross examination of the specimens confirmed the widening of the tracheal lumen compared with the previous diameter of the trachea without gross deformities in the reconstructed segments and good healing at the suture line without granulation tissue formation (Figure 3).
In this study, we achieved our goal of demonstrating the feasibility of applying slide tracheoplasty to long-segment acquired subglottic and upper tracheal stenosis. The surgical sites healed without granulation tissue or restenosis in all animals. The goal of this study was not to compare this technique with untreated surgically induced subglottic stenosis or to compare it with other surgical techniques; therefore, an untreated control group was not used.
The advantages of using the slide tracheoplasty technique in reconstructing the stenotic segment of the trachea are pointed out in the literature, especially in children with congenital long-segment tracheal stenosis. The primary technical advantage is reduction of the tension on the anastomosis produced by reducing the approximation distance. Furthermore, the vascularity of the tracheal cartilage is preserved, resulting in better healing.13
A few modifications in the technique were needed to apply it to the subglottic area. The proximal segment including the cricoid and the upper tracheal rings was split along its anterior wall and the distal segment along its posterior wall. This minimizes the possibility of injury to the recurrent laryngeal nerve, which comes into close proximity to the cricoid and first tracheal ring.
The mucosal healing was evident at all 3 examination times without any evidence of granulation tissue formation inside the tracheal lumen. Cartilage healing by fibrous tissue was seen at 4 weeks and progressed to mature fibrosis by 12 weeks. There were no anastomotic complications, granulation tissue formation, or disruption at the suture line at the last time of observation at 24 weeks.
Slide tracheoplasty in the management of acquired subglottic and upper tracheal stenosis is not meant to replace cricotracheal resection, but it can be of potential value in cases with mild to moderate stenosis and longer than 3 cm. It is actually like splitting and grafting the stenotic segment, but the graft is the anterior wall of the distal half of the stenotic segment.
Resection of a long segment of the trachea (≥3 cm) was shown previously to be a statistically significant risk factor for anastomotic complications after tracheal resection, probably because of the increased tension at the suture line.17 Slide tracheoplasty reduces the approximation distance by half and may result in reduction of this problem.
The application of slide tracheoplasty in the management of acquired subglottic and upper tracheal stenosis has some limitations including cases with grade 3 or 4 stenosis with thick scar tissue where cricotracheal resection will be the best option. Short stenotic segments (<3 cm) where cricotracheal resection could be performed without difficulty and stenotic segments with tracheomalacia when there is no cartilage can be used for reconstruction.
In conclusion, slide tracheoplasty can be used for the management of acquired subglottic and upper tracheal stenosis with a relatively long segment, with the following benefits: the use of native vascularized tracheal cartilage, which leads to better healing without granulation tissue formation; healing without a circumferential suture line, which would be a constrictive ring with further growth of the trachea; and decreasing the need for tracheal and laryngeal mobilization in acquired long-segment subglottic and upper tracheal stenosis by reducing the approximation distance by half.
Correspondence: Wael M. Abdelkafy, MD, 122 Street No. 6, El-Ballah Area, Ismailia, Egypt (firstname.lastname@example.org).
Submitted for Publication: August 21, 2006; final revision received November 13, 2006; accepted December 30, 2006.
Author Contributions: All authors had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Abdelkafy, El Atriby, Iskandar, and Mansour. Acquisition of data: Abdelkafy and Iskandar. Analysis and interpretation of data: Abdelkafy, Iskandar, and Mattox. Drafting of the manuscript: Abdelkafy, Mattox, and Mansour. Critical revision of the manuscript for important intellectual content: Abdelkafy, El Atriby, Iskandar, Mattox, and Mansour. Administrative, technical, and material support: Abdelkafy, El Atriby, Iskandar, and Mattox. Study supervision: Abdelkafy, El Atriby, Iskandar, Mattox, and Mansour.
Financial Disclosure: None reported.
Previous Presentation: This study was presented at the Combined Otolaryngological Spring Meeting (American Laryngological Association); May 20, 2006; Chicago, Ill.