Laryngospasm

• In short, laryngospasm arises due to some form of stimulation whilst in too light a plane of anaesthesia

• Although typically laryngeal stimulation, laryngospasm can arise from nasal, pharyngeal, tracheal or pulmonary stimulation by:
• Fluid e.g. blood, mucous
• Foreign bodies e.g. laryngoscope, endotracheal tube, NG tube etc.
• Volatile anaesthetics, typically desflurane or isoflurane
• In truly bizarre BJA paper from the 1970's it was found that ether, halothane and methoxyflurane can all cause laryngospasm in "decerebrate preparations of cats"

• Pain e.g. cannulation, surgical stimulus
• Cervical or anal dilatation

• Closure of the glottic opening is a reflex, protective mechanism against aspiration
• It can involve closure of the true and/or false vocal cords


• Constriction of the intrinsic laryngeal muscles occurs in response to peri-glottic stimulation
• The afferent pathway is via the internal branch of the superior laryngeal nerve, a branch of the vagus nerve


• The motor response includes constriction of posterior cricoarytenoids, lateral cricoarytenoids and thyroarytenoids
• All supplied by recurrent laryngeal nerve, a branch of the vagus nerve


• There may also be impaction of supraglottic soft tissue into the glottis by the increasing trans-laryngeal pressure


• Prolongation of the reflex, however, may lead to:
• Partial or complete upper airway obstruction with stridor, paradoxical respiratory movements and other signs of respiratory distress
• Hypoxia (almost universal)
• Bradycardia (6%)
• Negative pressure pulmonary oedema (4%)
• Aspiration (3%)
• Dysrhythmia
• Cardiac arrest (0.5%)

• Awareness of risk factors and address modifiable factors
• Use propofol induction as depresses airway reflexes
• Local anaesthetics e.g. 1mg/kg IV lidocaine, topicalisation of vocal cords


• Magnesium sulphate 15mg/kg prior to extubation
• Reduce secretions e.g. through atropine, glycopyrrolate
• Thorough suctioning prior to extubation
• Extubate either deep or awake, not in-between

Laryngospasm is an anaesthetic emergency and I would seek senior anaesthetic support as well as making a rapid but thorough assessment of the patient

• → Ask the surgeon to stop any surgical stimulus
• → Apply 100% oxygen
• → Start immediate management

• Remove any obvious stimulus, ensuring larynx is clear of fluids/blood/mucus
• Simple airway-opening manoeuvres and apply PEEP


• Deepen plane of anaesthesia e.g. propofol 0.5mg/kg
• Reportedly only fails to break laryngospasm in 14% of cases


• Paralysis e.g. suxamethonium
• Traditional intubating doses 1-2mg/kg IV or 2-4mg/kg IM
• Doses as low as 0.1mg/kg may be enough to break laryngospasm
• May necessitate re-intubation
• Intra-lingual and intra-osseous routes are also described


• Other described methods include:
• Opioids if painful stimulus is responsible e.g. alfentanil, pethidine
• Doxapram 1.5mg/kg increases ventilatory drive and may suppress the spasm
• Thoracic midline pressure/compressions at a rate of 20 - 25/min, which purportedly breaks spasm by forcing air through the vocal cords
• Larson's manoeuvre (bilateral pressure on the mastoid process), for which there appears to be little in the way of evidence

• If laryngospasm during induction there is a higher risk of laryngospasm at extubation
• Observe for 2 - 3hrs post-event to ensure clear airway and monitor for complications e.g. aspiration, negative-pressure pulmonary oedema
• Document in patient's notes ± critical incident form