Bronchospasm and laryngospasm

What it is

Bronchospasm and laryngospasm are two reflex airway emergencies that cause sudden difficulty ventilating under anaesthesia. Bronchospasm is a reversible constriction of the smooth muscle of the bronchi and bronchioles. It is more likely in patients with asthma, chronic obstructive pulmonary disease, a recent respiratory infection or smoking, and is triggered by airway instrumentation under light anaesthesia, aspiration, anaphylaxis and drugs that release histamine. It shows as wheeze or a silent chest, high airway pressures, a prolonged expiration with an upsloping capnography trace, and falling saturation. Laryngospasm is a forceful closure of the vocal cords by the intrinsic laryngeal muscles in response to stimulation such as secretions, blood or airway manipulation during light anaesthesia, typically at induction or at extubation; it is more common in children and after recent upper respiratory infection. Partial laryngospasm gives stridor; complete laryngospasm is silent, with chest movement but no air flow and no capnography trace. Both are treated by calling for help, giving pure oxygen, removing the stimulus and deepening anaesthesia; bronchospasm then needs bronchodilators, and laryngospasm that persists needs a neuromuscular blocker. Before blaming the patient, always exclude a kinked, blocked or misplaced tube.

How to recognise it

• Bronchospasm: wheeze or a silent chest, rising airway pressures, small delivered breaths, prolonged expiration.
• Capnography in bronchospasm shows a slanted upstroke without a plateau; end-tidal CO2 may fall as ventilation fails.
• Laryngospasm: inspiratory stridor (partial) or no air movement at all (complete), with tracheal tug and paradoxical chest and abdominal movement.
• Desaturation follows, and in children bradycardia can appear quickly.
• Both often occur during light anaesthesia: at induction, airway insertion or extubation.

Why it happens

• Irritation of airway receptors under light anaesthesia triggers vagal reflexes that contract bronchial muscle or close the glottis.
• Asthma, smoking and recent infection make the airways hyper-reactive for weeks.
• Laryngospasm is a protective reflex that keeps foreign material out of the trachea, exaggerated when anaesthesia is neither deep nor fully reversed.
• Narrow airways raise resistance; in bronchospasm air is trapped behind closing airways, raising intrathoracic pressure and lowering venous return.

What to do at once

1. Call for help and give pure oxygen — both crises desaturate quickly and need extra hands.
2. Stop surgical or airway stimulation and suction blood or secretions — removing the stimulus ends the reflex.
3. Check the tube, circuit and position, and hand-ventilate to feel compliance — a kinked, blocked or endobronchial tube mimics bronchospasm.
4. Laryngospasm: jaw thrust with firm pressure behind the angle of the mandible and a tight mask with continuous positive pressure — this opens the cords.
5. Laryngospasm: deepen anaesthesia with intravenous propofol — deeper anaesthesia abolishes the reflex.
6. Laryngospasm that persists with falling saturation: give suxamethonium, ventilate and intubate if needed; atropine for bradycardia in children.
7. Bronchospasm: deepen anaesthesia with a volatile agent, propofol or ketamine — they relax bronchial smooth muscle.
8. Bronchospasm: give an inhaled beta-2 agonist through the circuit, with ipratropium if needed — bronchodilators relieve the constriction.
9. Severe bronchospasm: adrenaline, intravenous magnesium and steroids; slow rate with long expiration — avoids gas trapping.
10. If pressure falls with bronchospasm, briefly disconnect the circuit to let trapped gas escape — dynamic hyperinflation compresses the heart.

Bronchospasm and laryngospasm side by side

Costly mistakes

• Treating «bronchospasm» that is really a kinked or blocked tube, an endobronchial tube or a pneumothorax.
• Missing anaphylaxis as the cause of bronchospasm, especially with hypotension or skin signs.
• Ventilating fast with short expiration in bronchospasm, building up gas trapping and causing hypotension.
• Extubating in the light plane between deep and awake, the moment laryngospasm is most likely.
• Forgetting negative-pressure pulmonary oedema after a laryngospasm against a closed glottis.

Next step

• After the event, examine the chest and get a chest radiograph if there is concern for aspiration, pneumothorax or pulmonary oedema.
• Observe in recovery for recurrent bronchospasm, desaturation and pink frothy sputum from negative-pressure pulmonary oedema.
• Call a senior early if saturation keeps falling, ventilation is impossible or the patient needs intensive care.
• Continue bronchodilators and review the asthma or COPD treatment; consider postponing elective surgery after a recent respiratory infection.
• Record the event and its cause and tell the patient; note the risk for future anaesthetics.

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Elsewhere in DurgiPedia

• Airway resistance
• Bronchial obstruction syndrome
• Opening the airway: head tilt, jaw thrust and simple adjuncts
• Bag-mask ventilation
• Airway suctioning: oral, nasal and artificial airways

Connections

← All of anaesthesia

Educational content; it does not replace supervised training, your institution's protocols or the anaesthetist's or intensivist's decision. It contains no doses and no ventilator or infusion settings.

Sources: Pediatric Bronchospasm (StatPearls (NCBI Bookshelf), 2023); Difficult Airway (StatPearls (NCBI Bookshelf), 2026).

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