Bronchospasm

This is an anaesthetic crisis. Priority is to:

  • Maintain oxygenation
  • Keep Pip < 50cmH2O

Emergency Management

Immediately:

  • Cease surgical stimulation
  • Provide 100% oxygen
  • Manually ventilate
    Assess lung resistance and compliance.
  • Rapidly deepen anaesthesia
    • Change from desflurane if able
  • Consider:
    • Is this anaphylaxis?
      Cause of ~20% of bronchospasm.
    • If intubated:
      Exclude endobronchial or oesophageal intubation.
    • If not intubated:
      • Exclude laryngospasm or airway obstruction
      • Exclude regurgitation or aspiration
  • Bronchodilate
    • Inhaled therapies
      Typically adequate in mild bronchospasm.
      • Salbutamol
        12 puffs MDI via circuit.
      • Ipratropium Bromide
        6 puffs MDI via circuit.
    • IV therapies
      Required in severe bronchospasm.
      • Salbutamol
        5ug/kg up to 250ug slow push, with a 100ug/kg/hr infusion.
      • Adrenaline 0.1-1ug/kg bolus, with a 0.1ug/kg/min infusion.
  • Optimise ventilation
    • I:E ratio of at least 1:6
    • Low RR
      Target complete expiration on expiratory flow waveform, accepting hypercapnoea.
    • Consider ventilator disconnection if concern for stacked breaths
  • Consider additional drugs
    • Hydrocortisone
      1-2mg/kg IV.
    • Ketamine
      0.5-1mg/kg IV.
    • Magnesium
    • Aminophyline
      5-7mg/kg over 15 minutes, then 0.5mg/kg/hr thereafter.

Epidemiology and Risk Factors

Epidemiology:

  • Majority of bronchospasm occurs during induction or maintenance
    Bronchospasm due to anaphylaxis predominantly occurs during maintenance.

Risk factors:

  • Asthma/COAD
  • Reflux
  • Heavy smokers
  • Recent URTI
  • Prior laryngospasm

Pathophysiology

Clinical Manifestations

Typically presents as a triad of:

  • Expiratory wheeze
  • Prolonged expiration time
    “Obstructed” capnographic waveform.
  • High Pip
    First sign in 30% of cases.

Clinical features:

  • Desaturation/cyanosis
    First sign in 20% of cases.
  • Hypercapnoea
  • Poor lung compliance
    • Fall in tidal volumes
    • Difficulty hand ventilating
  • Wheeze
    May not be present in severe spasm when gas flow is impaired, but is the first sign in 30% of cases.

History

Examination

Diagnostic Approach and DDx

Key differential diagnoses:

  • Anaphylaxis
  • Laryngospasm
  • Endobronchial intubation
    Also causes high airway pressures/reduced volumes and reduced SpO2~.
  • Poor chest wall compliance
    • Eschar
    • ‘Wooden Chest’ phenomenon
  • Poor lung compliance
    • PTHx

Investigations

Management

Marginal and Ineffective Therapies

Complications

Prognosis

References

  1. Westhorpe RN, Ludbrook GL, Helps SC. Crisis management during anaesthesia: bronchospasm. Qual Saf Health Care. 2005;14(3):e7. doi:10.1136/qshc.2002.004457