DEFINITION The harsh, high-pitched sound of laryngeal and upper tracheal obstruction.  

Do not delay if you are called for stridor. Even well-looking patients can decompensate rapidly.


Immediate measures 

1. Intensive monitoring eg emergency department Resus. If you are on a ward, alert the emergency team. Get the crash trolley or emergency equipment. Monitor oxygen saturations and respiratory rate closely.

2. Keep everyone calm. This is very distressing for the patient so do not add to their burden. Allow the patient to stay in whatever position they feel most comfortable, but encourage them that sitting upright is usually best for their breathing.

3. High flow oxygen. If humidification is immediately available, consider it. In children, only offer oxygen and nebulisers if tolerated or in extremis.

4. Nebulised adrenaline (1mg = 1ml of 1:1000 adrenaline; you can try between 1mg and 5mg driven on oxygen), assess response and repeat if necessary.

5. Call for specialist help: experienced anaesthetist, experienced ENT surgeon.

6. If the patient can tolerate it (or is in extremis), secure wide-bore IV access and send blood including group and save. If possible, take a blood gas and blood cultures. In children or agitated adults, wait for specialist help to arrive before attempting cannulation. 

7. High dose steroid eg dexamethasone 8mg IV initially. 

8. Avoid putting instruments in the mouth until specialist help arrives (unless the patient arrests).

9. Some institutions have Heliox, a mixture of helium and oxygen, which can reduce the work of breathing. It can be used if readily available but do not delay if it isn't.

10. Take a history and examine the patient. Treat the cause.

11. Endotracheal intubation should be first-line for acute airway compromise but sometimes it is not possible and a surgical airway is needed (also called 'front of neck airway' or FONA). 

A recent consensus developed by the Royal College of Anaesthetists and ENT UK states that the standard emergency FONA should be a scalpel-bougie cricothyroidotomy.

Open scalpel-bougie cricothyroidotomy

Needle cricothyroidotomy 



  • Rapid onset aphagia or severe dysphagia, frequently associated with a severe sore throat
  • Rapid onset laryngeal voice change: hoarse, croaky, husky or no voice
  • Systemically very unwell: pyrexia, tachycardia, tachypnoea

There may be associated trismus or torticollis. Beware of any patient who develops these signs after admission: situations deteriorate rapidly. In the presence of neck trauma, any of the above should be taken very seriously. Stridor is a late sign of airway compromise. 


Causes of airway obstruction

The causes of obstruction of any luminal structure can be divided into:

1. Outside the wall (extramural)
2. In the wall (intramural)
3. Inside the lumen (intraluminal)

Extramural - tumour, abscess or haematoma in the neck
Intramural - tumour of the larynx, paralysis of the vocal cords, epiglottitis, subglottic stenosis
Intraluminal - foreign body, blood or secretions inside the airway


Page last reviewed: 17 September 2017