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Anaesthetic Emergencies

Key Points ⚡

  • Life-threatening events requiring immediate recognition, escalation, and treatment.
  • Common emergencies: laryngospasm, malignant hyperthermia, anaphylaxis, local anaesthetic toxicity.
  • General management principle: recognise symptoms, call for help early, initiate treatment promptly.

Laryngospasm

Definition

  • Complete or partial reflex closure of the vocal cords causing airway obstruction.

Risk Factors

  • Recent upper respiratory tract infection (up to 6 weeks prior), GORD, airway manipulation, tonsillectomy, thyroid surgery (superior laryngeal nerve injury), young age, asthma, smoking.

Clinical Features

  • Stridor, abnormal see-saw abdominal and chest movements in spontaneously breathing patient.

Management

  • Remove stimulus (e.g. suction blood/mucus, remove airway devices).
  • Call senior anaesthetic help.
  • Administer 100% oxygen with high PEEP.
  • Deepen anaesthesia with propofol.
  • If unresolved, give suxamethonium (depolarising muscle relaxant) to relax vocal cords and consider intubation.
  • Exercise caution during extubation to prevent recurrence.

Complications

  • Hypoxia, negative pressure pulmonary oedema, bradycardia (especially in children).

Malignant Hyperthermia (MH)

Definition

  • Autosomal dominant disorder caused by mutation leading to abnormal intracellular calcium release causing sustained muscle contraction.

Triggers

  • Volatile anaesthetic agents (e.g. sevoflurane), suxamethonium.

Clinical Features

  • Masseter muscle spasm, generalized muscle rigidity, rising end-tidal CO2, rapid hyperthermia, rhabdomyolysis, hyperkalaemia.

Management

  • Call senior anaesthetic help.
  • Stop volatile agents immediately; disconnect from anaesthetic machine.
  • Administer 100% oxygen and hyperventilate to reduce CO2.
  • Switch to total intravenous anaesthesia (e.g. propofol).
  • Administer dantrolene (ryanodine receptor antagonist).
  • Actively cool patient (ice packs, cold saline infusion, abdominal lavage if open).
  • Monitor urine output aiming for >2 ml/kg/hr.
  • Treat hyperkalaemia with insulin/dextrose or sodium bicarbonate as needed.
  • Admit to critical care for monitoring.

Complications

  • Hyperkalaemia, acute renal failure, life-threatening arrhythmias.

Anaphylaxis

Definition

  • Acute IgE-mediated type 1 hypersensitivity reaction triggered by exposure to allergens such as antibiotics, muscle relaxants, latex.

Clinical Features

  • Urticaria, generalized rash, lip/tongue swelling, hypotension, tachycardia, bronchospasm, wheezing.

Management

  • Stop suspected causative agent.
  • Call for help.
  • Administer 100% oxygen.
  • Give adrenaline 0.5 ml of 1:10,000 IV or 0.5 ml of 1:1,000 IM if no IV access; repeat every 3-5 minutes as needed.
  • Nebulised or IV salbutamol for bronchospasm.
  • May require critical care input post-event.

Local Anaesthetic Toxicity

Definition

  • Systemic toxicity due to accidental intravascular injection or impaired clearance of local anaesthetics causing CNS and cardiac effects.

Risk Factors

  • Injection site vascularity (intercostal > caudal > epidural > brachial plexus > subcutaneous), comorbidities reducing clearance (liver, renal, cardiac disease).

Clinical Features

  • Altered mental status, seizures, agitation, coma.
  • Cardiac arrest, arrhythmias.
  • Perioral tingling and numbness.

Management

  • Stop local anaesthetic injection immediately.
  • Call for help.
  • Secure airway, administer 100% oxygen with hyperventilation to correct acidosis.
  • Treat seizures with benzodiazepines or small doses of propofol/thiopentone.
  • Administer lipid emulsion therapy:
  • Bolus 1.5 ml/kg Intralipid 20% IV over 1 minute, then continuous infusion at 15 ml/kg/hr.
  • Repeat bolus up to 3 times if needed until cardiovascular stability.
  • Transfer to ICU for monitoring.
  • Manage cardiac arrest with CPR, ALS, and continue lipid therapy.

References

  • Association of Anaesthetists of Great Britain and Ireland. Quick Reference Handbook of Anaesthetic Emergency, 2022.
  • Oxford Handbook of Anaesthesia, 3rd Edition, Emergencies in Anaesthesia, 2011.
  • Complications of Anaesthesia
  • Organ Donation and Brainstem Death Testing
  • Regional Anaesthesia