Tracheobronchomalacia

Weakness of the tracheal and bronchial walls (cartilage in the primary form, or the posterior membrane in excessive dynamic airway collapse) that allows more than 50% narrowing of the lumen on expiration.

• Primary (congenital): occurs in premature infants and with oesophageal atresia, tracheo-oesophageal fistula, vascular rings, Marfan and other connective tissue diseases, and in about 1 in 2100 children; the airway often improves by age 2 to 3 years.
• Secondary (acquired): long-term intubation or tracheostomy, chronic obstructive pulmonary disease and recurrent infection, relapsing polychondritis, external compression (goitre, aneurysm, vascular ring, mediastinal mass), and post-lung transplant.
• Prevalence in adults is difficult to establish, and has been reported in about 4 to 13% of patients with chronic respiratory symptoms investigated by bronchoscopy.
• Mechanism: raised intrathoracic pressure on expiration collapses the weakened airway, trapping secretions and causing barking cough, wheeze and recurrent infection.

Barking or brassy cough, expiratory wheeze or stridor, breathlessness, difficulty clearing secretions, recurrent bronchitis or pneumonia, wheeze that does not respond to bronchodilators (and that may worsen with them), exertional intolerance, and cough syncope.

• Infants: noisy breathing worse with crying or feeding, recurrent chest infection, dying spells (apnoea, cyanosis) especially after feeding, failure to thrive.
• Symptoms are worse lying flat, during exertion, coughing and with infection.
• Differential diagnosis: asthma, chronic obstructive pulmonary disease, bronchiectasis, vocal cord dysfunction, laryngomalacia, vascular ring, tracheal stenosis, tracheal tumour, foreign body, reflux related cough, heart failure.
• Complications: recurrent pneumonia, bronchiectasis, respiratory failure, cough syncope, chronic cough, hypoxic spells and sudden death in infants, failed extubation.

Dynamic expiratory CT (end inspiration and dynamic or end expiration images): expiratory narrowing of the cross-sectional area by more than 50% (mild 50 to 75%, moderate 75 to 90%, severe more than 90%); also shows crescent or saber-sheath shape, cartilage abnormality, calcification and external compression.

• Flexible bronchoscopy during spontaneous breathing and cough (the reference test): confirms the collapse, shape and site, and excludes other causes; do not use positive pressure ventilation during the assessment.
• Spirometry: flow-volume loop with expiratory flow limitation and a flattened expiratory limb; reduced peak flow.
• Barium swallow or CT angiography for suspected vascular rings or tracheo-oesophageal fistula in children; MRI.
• Temporary silicone stent placement for 2 to 4 weeks to predict whether surgical splinting will improve symptoms.
• Overnight sleep testing and oximetry when hypoventilation is suspected; assessment of reflux and aspiration; screening for relapsing polychondritis (ear, nose, joint and eye involvement, raised inflammatory markers, antibodies to type II collagen).

Conservative care for mild to moderate disease:

• Treat infection promptly: amoxicillin-clavulanate 625 mg three times daily for 7 days (children 25 to 30 mg/kg of the amoxicillin component three times daily); doxycycline 200 mg then 100 mg daily in penicillin allergy.
• Airway clearance: positive expiratory pressure device, active cycle of breathing technique, assisted cough, hypertonic saline 3% to 7% 4 mL twice daily after salbutamol.
• Treat reflux: omeprazole 20 to 40 mg daily for 8 weeks.
• Smoking cessation, vaccination (influenza, pneumococcal), optimisation of chronic obstructive pulmonary disease with tiotropium 18 micrograms daily; bronchodilators help only if there is coexisting airway disease, and should be stopped if symptoms worsen.
• Avoid cough suppressants that cause secretion retention.

```{=html} <!-- --> ``` - Continuous positive airway pressure of 5 to 15 cmH2O (titrated to splint the airway during expiration) at night and during infections; non-invasive ventilation for respiratory failure; in infants CPAP of 5 to 8 cmH2O.

• Silicone stent (a temporary test, or as definite treatment for severe disease in patients who are not surgical candidates); complications are migration (10 to 20%), mucus plugging, granulation, infection and stent fracture; remove at 4 to 6 weeks if there is no benefit.
• Surgery for severe disease with symptoms and a positive stent result:
  • Tracheobronchoplasty (posterior membrane splinting with mesh): symptom and quality of life improvement in about 70 to 90%, with a perioperative complication rate of about 10 to 30%.
  • Aortopexy or posterior tracheopexy for infants with vascular compression, and division of vascular rings.
  • Tracheostomy with ventilatory support in severe infantile disease, with a long cannula that bypasses the malacic segment.
• Relapsing polychondritis: prednisolone 0.5 to 1 mg/kg daily with taper over months, methotrexate 15 to 20 mg weekly with folic acid 5 mg weekly, or tocilizumab; specialist-led.
• Treat external compression: surgery for goitre, aneurysm or mass.
• Special groups: children (most primary disease improves with growth; avoid beta agonists if they worsen symptoms; admit with dying spells; nutrition support); pregnancy (CPAP, physiotherapy, and early review since symptoms worsen); elderly (CPAP is better tolerated than surgery); anaesthesia (retain spontaneous ventilation when possible and avoid high peak pressures); renal impairment (no specific changes).
• Red flags: stridor at rest, dying spells in infants, respiratory failure, cough syncope, recurrent pneumonia, failed extubation, haemoptysis.
• Follow-up: review at 4 to 6 weeks, then every 3 to 6 months; flow-volume loop and CT every 1 to 2 years or with new symptoms; stent check bronchoscopy at 4 to 6 weeks and then every 3 to 6 months; children reassessed yearly until the symptoms settle.