Tracheal stenosis

Aetiology

• Tracheotomy
  • Severity of stenosis depends on extension of the defect, necrosis and infection
  • Symptoms can occur immediately after decannulation or years later
• Ventilation
• Trauma
• Malignancy

Presentation

• Dyspnoea on exertion is the main symptom
• Wheeze, stridor, cough, difficulty clearing secretions, recurrent URTI, hoarseness
• 50% reduction in cross-sectional area of trachea results in dyspnoea only with significant exertion, whereas narrowing of the lumen to <25% usually produces dyspnoea and stridor at rest
• A 5-6mm lumen reduces peak expiratory flow rate to 30%
• Usually have stridor or wheezing if they have significant airway obstruction

Workup

• Spirometry and flow volume loops are not helpful in diagnosis
• If no respiratory distress, CT is best
• Bronchoscopic evaluation will give diagnosis most of the time
  • Flexible bronchoscopy is ok for diagnosis, but rigid bronchoscopy is needed for intervention, especially in an emergency (dilation/core out of tumour/laser/stenting)
  • Look for anatomic location, proximal and distal extent, and diameter of stenosis

Indications for tracheal resection

• Post-intubation or post-tracheostomy stenosis
  • Prolonged cuff pressure causes full-thickness necrosis of the tracheal cartilage, causing symptoms from circumferential scar contracture 3-6 weeks after extubation
  • Stomal stenosis from tracheostomy occurs with scarring at the anterior tracheal defect (anterior narrowing with normal posterior membranous wall)
  • Post-intubation stenosis is amenable to dilation, whereas post-tracheostomy is not
• Trauma
• Inflammatory
  • Tracheal infections
  • Collagen vascular diseases
• Idiopathic tracheal stenosis
  • Occurs most commonly in 20-50yo women, focused at the level of the cricoid cartilage with varying degrees of subglottic involvement
• Primary tracheal tumours
  • Consider these for resection if they can be removed with less than half of the longitudinal length of the trachea, and do not have unresectable local extension
  • SCC
  • Adenoid cystic carcinoma
  • Carcinoid
  • Mucoepidermoid
• Local tumours with airway invasion
  • Almost never an indication for tracheal resection, but locally advanced thyroid cancer may be considered, even in the presence of metastatic disease (because prognosis is still pretty good)

Anaesthesia/airway management

• Stomal stenosis can nearly always be intubated without difficulty, whereas post-intubation stenosis might be harder
• Anaesthesia for tracheal resection is normally given as mixed inhalational/IV, while maintaining spontaneous ventilation until airway is established
• Aim to extubate in OT

Surgical technique

• Tracheal resection now thought to be safe up to 5-6cm
• Most benign stenoses approached through neck incision - thoracotomy rarely required

Post-op support

• Manually support neck flexion to prevent hyper-extension and associated strain on anastomosis
• Laryngeal oedema manifests within 24-72 hours and typically resolves without any intervention
• Subcutaneous emphysema post-op likely represents anastomotic dehiscence - surgical emergency - needs airway secured - bronchoscopy to evaluate anastomosis