FRCA Notes

Bronchospasm

The curriculum asks us to know 'the causes, detection and management of... bronchospasm'.

Resources

  • Bronchospasm is, as its name describes, a pathological constriction of the bronchioles leading to obstructed air flow and thus impaired oxygenation/ventilation
  • Overall incidence 0.21%, although more common in those with reactive airway disease (2%)

Risk Factors

  • Reactive airways disease e.g. asthma, COPD
  • Smoking
  • History of atopy
  • Recent or active URTI
  • Induction or maintenance phases of anaesthesia

Aetiologies

  • Anaphylaxis
  • Drugs
    • Histamine-releasing drugs e.g. morphine, benzylisoquinolinium NMBA
    • NSAIDs
    • Neostigmine
    • Blood products
    • Isoflurane and desflurane (due to airway irritation)
  • Irritation by endotracheal intubation or other foreign material e.g. aspiration
  • Stimulation under too light a depth of anaesthesia

  • Expiratory wheeze
  • Reduced or absent breath sounds
  • Silent chest
  • Prolonged expiration

  • Ventilation
    • Raised inflation pressures
    • Reduced tidal volumes
    • Upsloping capnograph trace

  • Hypoxia
  • Hypercapnoea
  • Features of underlying cause e.g. cardiovascular instability in anaphylaxis

  • Mechanical obstruction to airflow e.g. kinked, blocked or misplaced endotracheal tube
  • Tracheobronchial tree obstruction due to other cause e.g. laryngospasm, foreign body
  • Wheeze from other aetiology e.g. ARDS, pulmonary oedema
  • Other causes of raised ventilatory pressure e.g. reduced lung compliance, pneumothorax

  • Optimise control of airways disease
  • Smoking cessation
  • Continue bronchodilator and corticosteroid therapy until time of surgery
  • Consider chest physiotherapy e.g. to aid sputum clearance
  • Avoidance of NSAIDS in those with known reactivity
  • Postponing those at high risk e.g. recent or active URTI
  • Avoidance of GA e.g. regional techniques
  • Avoidance of ETT (i.e. use SAD)

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

Initial assessment

  • Call for help
  • Stop the surgeons

  • Increase FiO2 to 1.0
  • Increase depth of anaesthesia, esp. as volatiles bronchodilatory

  • Airway and respiratory assessment to exclude some differentials
    • Auscultate for wheeze (e.g. inspiratory noise might indicate laryngospasm)
    • Check for bilateral air entry (e.g. has there been endobronchial intubation)
    • Expose the chest
    • Percuss (e.g. is there hyper-resonance indicative of pneumothorax)
    • Check the breathing circuit for kinking or blockages

Pharmacological management

  • Salbutamol MDI 8 puffs down ETT (remove HME first) is first line
  • Salbutamol via other routes:
    • Nebulised 5mg
    • IV bolus 250μg (slow)
    • IV infusion 5 - 20μg/min
Drug Adult dose
Ipratropium 0.5mg nebulised
Adrenaline 5ml 1:1,000 nebulised
10-100μg IV bolus
500μg IM
Magnesium 2g IV over 20mins
Ketamine 20mg IV bolus
1-3mg/kg/hr IV infusion
Aminophylline 5mg/kg loading dose over 20mins
0.5mg/kg/hr maintenance infusion

Ventilatory strategy

  • Increase expiratory time to allow complete expiration e.g. slower RR and I:E at least 1:2 if not greater e.g. 1:3, 1:4 or beyond
  • Pressure control ventilation
  • May need low tidal volumes to avoid excessive airway pressures
  • Permissive hypercapnia may be appropriate e.g. pH >7.20
  • Beware of breath stacking/dynamic hyperinflation

Ongoing management

  • Corticosteroids e.g. hydrocortisone 200mg 6hrly IV
  • Depending on nature of surgery may be appropriate to proceed or cancel surgery
  • Consider need for HDU or ICU care