A 9 mm Trachea, a Substernal Goiter, and a Stridor That Worsens When Supine

This is a fixed upper airway obstruction and the default assumption must be that it is critical. The lesion narrows the trachea to 9 mm, and stridor at rest means airflow is already at a flow-limiting point. Propofol or a muscle relaxant abolishes the negative intrathoracic pressure that is currently stenting the airway open, and positive-pressure ventilation does not reliably overcome a rigid extrathoracic narrowing - it can worsen collapse or push the mass against the trachea. Therefore the plan is awake, spontaneous-ventilation tracheal intubation with the airway secured before any induction agent or relaxant.

Concretely: glycopyrrolate to dry secretions, careful topicalisation (4% lidocaine to oropharynx, 2% via the working channel to the cords and trachea), nasal or oral flexible bronchoscope with a 6.0 mm armoured tube loaded and railroaded over the scope; high-flow nasal oxygen at 40–60 L/min throughout for apnoeic oxygenation. Two operators, two suction catheters, and a planned sequence: fail → switch to awake video-laryngoscopy with a hyperangulated blade to lift the mass, still without relaxant. ENT surgeon scrubbed and gowned with a rigid bronchoscope and tracheostomy set open in theatre from the outset. I would not give a neuromuscular blocker until the tube is in the trachea, position confirmed by capnography with a good waveform, and ventilation demonstrated while the surgeon is present. If topicalisation fails or the patient cannot tolerate the scope, the fall-back is a gas induction with sevoflurane in the sitting position, maintaining spontaneous ventilation throughout - never a masked rapid-sequence induction.

Escalate in a defined order while continuously re-oxygenating. The desaturation to 91% is my signal to act quickly but not to abandon spontaneous ventilation.

1. Smallest scope first: exchange to a 3.5–4 mm flexible scope that will likely pass a 9 mm lumen, then load the smallest tolerated tube (5.0–5.5 mm microlaryngeal or armoured tube) and railroad it. A small cuffed tube that works beats a large one that fails.
2. Change device rather than force: awake video-laryngoscopy to elevate the mass off the posterior tracheal wall and change the geometry; a rigid bronchoscope is the next option in ENT's hands, and its rigid nature lets you dilate and ventilate through an obstructed segment.
3. Optimise the physiology: sit him up, increase HFNO, stop any scope manipulation that triggers coughing, and let the SpO2 recover between attempts. Repeated prolonged attempts on an obstructed airway cause oedema and bleeding and are how partial obstruction becomes complete.

Criteria to stop and go surgical: falling SpO2 below ~88–90% despite maximal oxygen, inability to topicalise/agitation, bleeding obscuring the view, or any sudden loss of stridor with distress (silent chest = near-complete obstruction). My threshold is low: I would ask ENT to perform a tracheostomy or cricothyrotomy under local while the patient is still awake and sitting, accepting that the radiation field and substernal extension make a low tracheostomy difficult. I would not give a relaxant to 'buy a look' at this point.

This is likely tracheomalacia from long-standing compression, and the trachea will not stay open without stenting by positive pressure. Extubation criteria become different from the usual: the question is not only 'is he awake' but 'does the airway stay patent and is the surgical field safe'.

• Assess objectively: perform an air-leak test and a flexible bronchoscopy through the tube while the patient breathes spontaneously, watching for dynamic expiratory collapse of the softened segment. If the trachea collapses to a pinhole with each breath, the patient stays intubated.
• Stent with PEEP/CPAP: keep intubated and ventilate in an ICU with 5–10 cmH2O PEEP, sedation, head-up positioning, and a plan for a staged spontaneous breathing trial over 24–72 hours. Some patients need days for tracheal tone to recover; a small proportion need temporary stenting or even re-intubation after premature extubation.
• Before extubating: the surgeon must be at the bedside (or immediately available) for 30 minutes because post-thyroidectomy haematoma can obstruct a normal airway, let alone a malacic one; keep a tracheostomy set and a size-smaller tube at the bedside, and nurse the patient with the head elevated.
• Other post-thyroidectomy issues: check ionised calcium 6 and 24 hours (transient hypoparathyroidism), watch for stridor, and document vocal cord function if there is any change in voice, since recurrent laryngeal nerve injury plus malacia is a bad combination.