Chapter 19: ASTHMA

YOUR PATIENT

A 15-year-old male with asthma develops intraoperative bronchospasm.

PREOPERATIVE CONSIDERATIONS

The goal of preoperative assessment in an asthmatic patient is to gauge the severity and control of the asthma. Key factors in determining the severity of the asthma are:

• Number of acute exacerbations, hospital presentations, and admissions in a year

• Recent asthma symptoms, medical interventions, and hospital visits

• Level of maintenance therapy

• Albuterol frequency, recent use, and recent escalation of therapy

• Number of episodes of oral corticosteroid use for acute exacerbations within the past year

• Previous intensive care admission and invasive ventilation

• Any specific triggers for bronchospasm

• Presence of recent cold symptoms within the last two weeks

• Functional exercise tolerance is a useful marker of severity

A patient with severe asthmatic attacks is more likely to develop perioperative bronchospasm and would benefit from a preoperative consultation with a pulmonologist to optimize his or her asthma control.

Common triggers for childhood asthma exacerbation include the following:

• Upper respiratory infection (URI)—usually viral

• Smoke or other inhaled irritant gases

• Pollen

• Foreign bodies

Potential trigger agents should be identified and avoided. The usual inhaled and oral medications should be taken the day of surgery.

ANESTHETIC MANAGEMENT

• A patient with a history of prolonged oral prednisolone or high dose of inhaled corticosteroids within the previous 12 months may benefit from a single intraoperative dose of corticosteroids.

• Consider a premedication to avoid or reduce the patient’s anxiety upon induction. Crying or coughing during uncooperative inhalational induction may trigger acute bronchospasm.

• A deep plane of anesthesia reduces airway reactivity associated with intubation.

• Avoid carinal irritation, which may precipitate bronchospasm.

• Avoid irritant volatile agents (desflurane), which may precipitate bronchospasm.

• Consider the total intravenous anesthesia (TIVA) technique and regional anesthesia.

• Consider using ketamine for IV induction (1-2 mg/kg) and maintenance (12.5-45 μg/kg/min infusion) of anesthesia.

Intraoperative management of bronchospasm

• Ensure adequate oxygen delivery and carbon dioxide clearance.

• Eliminate mechanical causes: blocked or kinked endotracheal tube (ETT), carinal irritation, or a defective circuit.

• Eliminate other causes of increased airway pressures: pneumothorax, abdominal splinting due to light anesthesia, or anaphylaxis.

• Limit ventilator pressures to reduce risk of barotraumas and cardiovascular collapse: increase fraction of inspired oxygen (FiO₂), reduce respiratory rate, reduce inspiratory:expiratory (I:E) ratio (prolong expiratory time to avoid gas trapping).

• Deepen the level of anesthesia with volatile agents or with propofol.

• Inhaled albuterol (metered-dose inhaler [MDI] + spacer): up to 10 puffs (1 mg) every 20-30 minutes.

• Subcutaneous terbutaline 10 μg/kg (maximum dose of 250 μg).

• Aminophylline: 5-7 mg/kg IV over 30 minutes followed by a 0.5-1.5 mg/kg/h infusion.

• Corticosteroids:

  • Hydrocortisone 4 mg/kg IV

  • Methylprednisone 1 mg/kg IV

• Epinephrine (1:1000) IV: 1-10 mcg/kg:

  • Subcutaneous: 10 μg/kg (maximum dose of 400 μg)

  • ETT: 1 μg/kg

• Magnesium: 40 mg/kg IV over 20 minutes.

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