What is the appropriate immediate and preventive management of a ketamine‑induced laryngeal spasm?

Management of Ketamine-Induced Laryngospasm

Treat ketamine-induced laryngospasm identically to laryngospasm from any other cause, using the standardized algorithmic approach of immediate CPAP with 100% oxygen, followed by propofol and succinylcholine if needed, despite the paradox that ketamine itself can both cause and treat laryngospasm. 1, 2

Immediate Treatment Algorithm

Step 1: Recognition and Initial Response

• Call for help immediately upon recognizing laryngospasm, as this can progress to hypoxic cardiac arrest and death 2
• Recognize the characteristic inspiratory 'crowing' sound, marked suprasternal recession ('tracheal tug'), use of accessory respiratory muscles, and paradoxical thoracoabdominal movements 1, 2
• Complete obstruction presents with silent inspiration—do not wait for the patient to "open up" as the vocal cords will not spontaneously open before death occurs 1

Step 2: Apply Continuous Positive Airway Pressure

• Apply CPAP with 100% oxygen using a reservoir bag and facemask while ensuring the upper airway is patent 1, 2
• Avoid unnecessary upper airway stimulation during treatment, as this worsens or prolongs the laryngospasm 1, 2
• Perform Larson's manoeuvre: place the middle finger of each hand in the 'laryngospasm notch' between the posterior border of the mandible and the mastoid process while displacing the mandible forward in a jaw thrust with deep pressure 1

Step 3: Pharmacological Escalation if Laryngospasm Persists

• Administer propofol 1-2 mg/kg intravenously if laryngospasm persists and/or oxygen saturation is falling 1, 2
• While low doses may be effective in early laryngospasm, larger doses are needed in severe laryngospasm or total cord closure unresponsive to initial propofol 1

Step 4: Definitive Management for Worsening Hypoxia

• Administer succinylcholine 1 mg/kg intravenously if hypoxia worsens despite propofol, as this provides complete vocal cord relaxation, permitting ventilation, re-oxygenation, and intubation if necessary 1, 2
• In the absence of intravenous access, administer succinylcholine via intramuscular (2-4 mg/kg), intralingual (2-4 mg/kg), or intraosseous (1 mg/kg) routes 1, 2
• Atropine may be required to treat bradycardia following succinylcholine administration 1

Step 5: Surgical Airway in Extremis

• In extremis, consider a surgical airway if all other measures fail 1

Critical Pitfalls Specific to Ketamine-Induced Laryngospasm

The Ketamine Paradox

• Ketamine can both cause and prevent laryngospasm, creating a clinical paradox 1, 3, 4
• Case reports document severe laryngospasm occurring despite deep ketamine anesthesia and even neuromuscular blockade with succinylcholine, suggesting an idiosyncratic effect 3
• Recurrent episodes of intractable laryngospasm have been documented with intramuscular ketamine, sometimes requiring endotracheal intubation 4

Do Not Delay Escalation

• Do not delay escalation of treatment if initial measures fail, as laryngospasm can progress rapidly to complete airway obstruction and hypoxic cardiac arrest 1, 2
• The myth that "hypoxia will break the laryngospasm" is dangerous—the vocal cords will not open before death occurs 1

Apnea Risk with Ketamine

• Be aware that ketamine can cause apnea even at low doses (0.31 mg/kg has been reported to cause apnea in critically ill patients), particularly around the time of injection 5, 6
• A brief period of apnea around the time of ketamine injection is common, though significant cardiorespiratory adverse events are rare 6

Post-Event Monitoring

Watch for Post-Obstructive Pulmonary Edema

• Monitor for post-obstructive pulmonary edema, which develops in approximately 4% of laryngospasm cases 2
• Recognize the presentation: dyspnea, agitation, cough, pink frothy sputum, and low oxygen saturations 2
• This results from negative intrathoracic pressure created by forceful inspiratory efforts against an obstructed airway 1

Prevention Considerations

Risk Factors to Consider

• Laryngospasm risk is highest during lighter planes of anesthesia, though ketamine-induced laryngospasm can occur even with deep anesthesia 1, 3
• Higher risk occurs in children, smokers, patients with pre-existing airway infections, and during procedures involving airway manipulation with increased secretions 1