Tracheal Stenosis
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Direct answer
A patient who cannot be extubated after intensive care, or who presents weeks to months after a difficult intubation or tracheostomy with exertional dyspnoea and biphasic stridor often mislabelled as "asthma", has an acquired tracheal stenosis until proved otherwise — the commonest cause in adults is pressure necrosis from an endotracheal or tracheostomy tube cuff (cuff pressure above the mucosal capillary pressure of roughly 20–30 cm H2O) producing cartilage-level ischaemia, ulceration and a fibrous ring. Evaluation combines flow-volume loops (a fixed upper airway obstruction flattens both inspiratory and expiratory limbs), CT with multiplanar or virtual bronchoscopic reconstruction, and rigid bronchoscopy under anaesthesia — the gold standard that measures length and calibre and grades severity on the Myer-Cotton scale (grade I up to 50 per cent obstruction, II 51–70, III 71–99, IV no lumen). Treatment spans endoscopic dilation (temporising, high restenosis), laser radial incisions, stents or a Montgomery T-tube for patients unfit for open surgery, and definitive segmental tracheal resection with end-to-end anastomosis — safe for roughly half the adult trachea, about 4–5 cm, with release manoeuvres (laryngeal release, hilar release) and neck flexion extending the limits.
What you must remember
- Causes ranked: post-intubation or post-tracheostomy stenosis (cuff site and stoma site are the two classic levels) overwhelmingly commonest in adults; post-traumatic; tuberculous tracheitis (an important Indian cause, often long strictures); idiopathic subglottic stenosis (young women); Wegener granulomatosis, relapsing polychondritis, amyloidosis and extrinsic compression (goitre, vascular rings, mediastinal masses).
- Cuff pressure physiology: capillary perfusion pressure of tracheal mucosa is roughly 20–30 cm H2O; sustained higher cuff pressure (overinflation, low-volume high-pressure cuffs, prolonged ventilation) causes ischaemic ulceration exposing cartilage, granulation and finally a cicatricial ring.
- Presentation: dyspnoea on exertion progressing to stridor, biphasic (both phases) because the lesion is fixed; recurrent "failures" of weaning or extubation; acutely, biphasic stridor with saturation dips is an emergency — humidified oxygen, heliox, and senior airway help; never blindly paralyse and intubate across an unknown stenosis.
- Myer-Cotton grading (of subglottic/tracheal stenosis by cross-sectional area lost): I — under 50 per cent; II — 51–70 per cent; III — 71–99 per cent; IV — no detectable lumen. Grades III–IV and any significant symptoms generally need definitive intervention.
- Investigations: flow-volume loop (flattening of both limbs = fixed obstruction), CT with multiplanar reconstruction or virtual bronchoscopy to map length and level, and rigid bronchoscopy in theatre — which is both diagnostic and immediately therapeutic (dilation to secure the airway and size the lesion).
- Endoscopic options: gentle bougie or balloon dilation — immediate but usually recurs within weeks; radial laser incisions with dilation for short web-like stenoses; steroid injection into the ring mitigates restenosis in selected cases; silicone or (less favoured) covered metallic stents for palliation or unfit patients, with migration, granulation and infection as costs.
- Montgomery T-tube: a silicone T-shaped tube whose vertical limb exits through the stoma and whose horizontal limb stents the trachea across the stenosis, allowing speech and toilet — a bridge or destination device in unfit patients and after complex reconstruction.
- Definitive surgery: segmental resection with end-to-end anastomosis — the benchmark, with approximately up to half the adult trachea (about 4–5 cm) resectable safely; cricotracheal resection for subglottic involvement (cricoid split with mucosal preservation); release manoeuvres (suprahyoid laryngeal release, inferior hilar release) gain further length; postoperatively the neck is kept flexed (chin-to-chest stay sutures) to offload the anastomosis.
- Pitfalls after repair: anastomotic dehiscence and restenosis at the suture line, and injury to the recurrent laryngeal nerves; tracheostomy tubes, when needed long-term, should use soft, correctly sized cuffs at the lowest leak-proof pressure.
A typical case walked through
A 30-year-old woman, ventilated for two weeks after severe COVID pneumonia through an oral tube and then a tracheostomy, fails two extubation attempts over the next month and is labelled a difficult asthmatic; spirometry shows a flattened, truncated flow-volume loop with both limbs boxed. CT reconstruction demonstrates a 2 cm circumferential ring at the previous cuff level reducing the lumen to about 4 mm, with normal trachea above and below — post-intubation stenosis, Myer-Cotton grade III. Sequence the plan: secure the airway first — she is taken to theatre for rigid bronchoscopy, where the stenosis is dilated with bougies to buy an immediate, safe airway; because she is young, fit and has a short, well-localised stenosis, definitive treatment is segmental tracheal resection (two to four rings) with end-to-end anastomosis, done through a collar incision, keeping the neck flexed postoperatively with a chin stitch for about a week. She decannulates and breathes normally. The forks: a 60-year-old with poor respiratory reserve and a long, inflamed post-tubercular stricture is a poor resection candidate — she is better served by a silicone stent or a Montgomery T-tube with periodic changes; and a patient stenosing acutely while still in intensive care needs dilation as a bridge while inflammation matures — resecting an actively inflamed airway invites restenosis, so definitive surgery waits weeks to months.
Where students slip
First, the misdiagnosis: exercise dyspnoea and stridor after an intensive care stay get treated as asthma — the flow-volume loop with a fixed upper airway pattern is the discriminator the exam rewards. Second, quoting grades wrongly: Myer-Cotton grades follow percentage obstruction (I under 50, II 51–70, III 71–99, IV no lumen) — students invert them. Third, overestimating resectable length: about half the adult trachea (roughly 4–5 cm) without release, more with release manoeuvres — claiming the whole trachea can be resected is a viva-ending error, and forgetting neck flexion postoperatively misses the practical detail that protects the anastomosis.
Frequently asked questions
What is the commonest cause of acquired tracheal stenosis in adults?
Prolonged intubation or tracheostomy — cuff pressure necrosis above mucosal capillary pressure (about 20–30 cm H2O) at the cuff site, and scarring at the stoma site.
What does the flow-volume loop show in fixed tracheal stenosis?
Flattening of both inspiratory and expiratory limbs (a boxed pattern), distinguishing a fixed upper airway obstruction from the variable intrathoracic or extrathoracic patterns.
What are the Myer-Cotton grades?
Grade I — up to 50 per cent obstruction; II — 51–70 per cent; III — 71–99 per cent; IV — complete (no detectable lumen); grading guides endoscopic versus open management.
How much trachea can be safely resected in an adult?
Roughly half the tracheal length, about 4–5 cm, for primary end-to-end anastomosis; release manoeuvres (suprahyoid laryngeal release, hilar release) extend this further in selected cases.
What is a Montgomery T-tube?
A silicone T-shaped stent with an external limb through the stoma, stenting the trachea across a stenosis while permitting speech and airway toilet — used in unfit patients or as a bridge after complex reconstruction.