Acute Airway Obstruction and Stridor
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Direct answer
Stridor is turbulent airflow through a narrowed airway — an emergency sign, never a diagnosis — and its phase localises the obstruction: inspiratory stridor means a supraglottic or glottic lesion above the cords, biphasic stridor a subglottic or glottic lesion, and expiratory stridor a tracheobronchial obstruction below. Adult obstruction follows laryngeal carcinoma, bilateral vocal cord palsy, epiglottitis and deep neck infection, trauma, angio-oedema and foreign body inhalation. Management runs on two rails at once: stabilise — upright posture, humidified oxygen, nebulised adrenaline, corticosteroids, heliox — while preparing definitive control by intubation or tracheostomy in theatre with surgeon and anaesthetist together.
What you must remember
- Phase-to-level mapping: inspiratory stridor — lesion above the vocal cords (laryngomalacia, epiglottitis, supraglottic tumour); biphasic stridor — at or just below the cords (vocal cord palsy, subglottic stenosis, subglottic haemangioma); expiratory stridor or wheeze — tracheobronchial (tracheomalacia, extrinsic compression, foreign body).
- Concomitant signs of severity: stridor at rest, accessory muscle recession, intercostal and suprasternal indrawing, restlessness giving way to drowsiness (hypercapnia), cyanosis as a late sign, and the ominous quietening child whose obstruction has exhausted the airflow generating the sound.
- Adult causes ranked for the exam: laryngeal carcinoma with oedema or post-radiotherapy stenosis, bilateral abductor cord palsy, post-intubation oedema and subglottic stenosis, infection — acute epiglottitis, peritonsillar and retropharyngeal abscess, Ludwig's angina — trauma and burns inhalation, angio-oedema, and inhaled foreign bodies.
- Medical first aid: upright posture, humidified oxygen, nebulised adrenaline 1:1000 at 0.5 mL/kg up to 5 mL repeated as needed, intravenous dexamethasone, heliox as a bridge, and minimal handling in suspected epiglottitis — no tongue depressors, no supine positioning.
- Definitive airway options: orotracheal intubation with a smaller tube by the most experienced hands, awake fibreoptic intubation in predicted difficulty, tracheostomy under local anaesthesia when intubation is impossible, and cricothyroidotomy as the bedside rescue when everything else fails.
- Location doctrine: severe stridor moves to theatre for assessment, where tracheostomy can follow a failed intubation within the same minute.
- Sequence to recite in vivas: assess severity, call for senior anaesthetic and ENT help, stabilise medically, secure the airway in theatre, then treat the cause — in that order, every time.
A night call walked through
At 2 am a 58-year-old man, post-radiotherapy for laryngeal cancer, arrives with biphasic stridor, sitting bolt upright, saturating 88 percent, agitated. First actions buy time without provoking catastrophe: oxygen by mask, nebulised adrenaline, intravenous dexamethasone, and urgent calls to the anaesthetist and theatre team. He improves marginally — enough to reach theatre, not enough for the ward.
In theatre, neck prepared and tracheostomy set open, the anaesthetist attempts gas induction; when the view fails, the surgeon proceeds to tracheostomy under local anaesthesia. Once the airway is secure, the cause gets its turn: endoscopic assessment, then dilation, laser or laryngectomy discussion depending on pathology. Contrast a drooling three-year-old in tripod posture with a muffled voice: suspected epiglottitis, where the rule inverts — no throat examination, no lying down, calm on the parent's lap, oxygen, antibiotics after blood cultures, and theatre for controlled intubation with tracheostomy readiness. Same sign, opposite handling, both examinable verbatim.
Where examiners dig
The first probe is physiological: why is extrathoracic obstruction inspiratory? Because during inspiration the extrathoracic airway narrows under negative intraluminal pressure while intrathoracic airways expand — the Bernoulli and transmural pressure logic reversed in expiration — a short answer that carries a full mark. The second is the management hierarchy: candidates who write "intubate immediately" for a quinsy or epiglottitis without theatre preparation fail the practical; the safer doctrine is stabilise, mobilise seniors, and secure the airway where surgical rescue is immediate. Third, the distinction between stridor and stertor — stertor is pharyngeal, supraglottic and crow-like; stridor is laryngotracheal — a one-line discrimination that opens many a viva station.
Frequently asked questions
What does the phase of stridor tell about the level of obstruction?
Inspiratory stridor indicates a supraglottic or glottic lesion, biphasic stridor a glottic or subglottic lesion, and expiratory stridor a tracheobronchial obstruction below the thoracic inlet.
What is the immediate medical management of acute severe stridor?
Upright posture, humidified oxygen, nebulised adrenaline (1:1000, 0.5 mL/kg up to 5 mL), systemic corticosteroids, minimal handling, and urgent mobilisation of anaesthetic and surgical help.
Why should a child with suspected epiglottitis not have the throat examined?
Instrumentation or distress can precipitate complete obstruction; the child is kept calm and taken to theatre for controlled airway management.
When is tracheostomy preferred over intubation in airway obstruction?
When intubation is impossible or hazardous — gross laryngeal tumour, severe subglottic stenosis, angio-oedema, failed views — tracheostomy under local anaesthesia in theatre secures the airway directly.
What is the role of heliox in acute airway obstruction?
A helium-oxygen mixture is less dense than air, lowering turbulent flow resistance across the obstruction — a temporising bridge that buys minutes while definitive airway control is arranged.