Asthma

About this video

• Video Title: Asthma
• Channel: Emergency Medicine with Dr Soran
• Speakers: Dr Soran
• Duration: 00:16:13

Overview

This video provides a comprehensive overview of asthma, defining it as a chronic inflammatory disorder of the airways characterized by variable airflow obstruction. It details the clinical features for diagnosing asthma, methods for assessing its severity, and outlines the key treatment strategies, including oxygen administration, bronchodilators, steroids, and other interventions for severe or life-threatening cases. The video also touches on investigations, discharge planning, and when to consider intensive care referral.

Key takeaways

• Definition of Asthma: Asthma is a chronic inflammatory condition of the airways leading to reversible airflow obstruction, characterized by airway swelling and bronchoconstriction.
• Diagnostic Clues: Key symptoms include breathlessness, chest tightness, and wheezing, with diurnal variation (worse at night/early morning), exercise/cold/allergen triggers, atopic history, and improvement with bronchodilators increasing the probability of asthma.
• Severity Assessment: Asthma severity is assessed using clinical features, vital signs (respiratory rate, heart rate, SpO2), and objective measurements like Peak Expiratory Flow Rate (PEFR) compared to the patient's best or predicted values. Categories include moderate, severe, life-threatening, and near-fatal.
• Treatment Modalities: Primary treatments involve oxygen, short-acting beta-2 agonists (like salbutamol), ipratropium bromide, and steroids. For severe or resistant cases, magnesium sulfate, aminophylline, or adrenaline may be used. Mechanical ventilation is considered for life-threatening situations.
• Discharge and Follow-up: Patients discharged after an asthma exacerbation should receive oral steroids for a short duration, inhaled bronchodilators, and have their inhaler technique checked. Follow-up with a respiratory medicine specialist within 48 hours is recommended.

The management of asthma, as detailed in the video, can be broken down into several key components:

1. Initial Management for All Patients:

• Oxygen: Administered immediately to any hypoxic patient. It should be titrated to maintain an SpO2 between 94-98%. Various delivery methods are discussed:
  • Face Mask: Provides 40-60% oxygen at 10-15 L/min.
  • Non-rebreathing Mask (with reservoir bag): Can deliver almost 100% oxygen.
  • Nasal Cannula/Nasal Mask: Less suitable for asthma, providing only 20-40% oxygen at a maximum of 6 L/min due to potential for nasal dryness and injury.
• Beta-2 Agonists: Salbutamol is the first-line treatment to relieve bronchospasm.
  • In children, it should be given via a spacer device.
  • For severe cases, doses can be increased (e.g., 15 mcg/kg/min in pediatrics).
  • Common side effects include tremor, tachycardia, and vomiting.
  • Salbutamol can be given in repeated or "back-to-back" doses.
• Steroids:
  • Oral Steroids: Prednisolone (40-50 mg) or hydrocortisone (IV/IM, 100 mg every 6 hours) are used.
  • Inhaled Steroids: Budesonide or beclomethasone can also be used, sometimes to aid bronchodilation.
  • Dosing for children varies by age: <2 years (10 mg), 2-5 years (20 mg), >5 years (30 mg) of prednisolone.
• Ipratropium Bromide (Atrovent): An anticholinergic bronchodilator.
  • Dose: 500 mcg (0.5 mg) as a bolus.
  • Can be added to beta-agonists in severe, life-threatening asthma or when there's a poor response to beta-agonists.
  • Can be given every 4-6 hours.

2. Management Based on Severity:

• Moderate Asthma: Patients without features of severe asthma, with increasing symptoms, shortness of breath, and PEFR 50-75% of best/predicted. Managed with the initial treatments.
• Severe Asthma: Patients unable to complete a sentence in one breath, with PEFR 33-50% of best/predicted, respiratory rate ≥25, and heart rate ≥110. Management includes initial treatments plus close monitoring of vital signs and PEFR.
• Life-Threatening Asthma: Characterized by silent chest (no wheezing), cyanosis, feeble respiratory effort, arrhythmias, hypotension, altered consciousness.
  • PEFR is <33% of best/predicted (difficult to measure).
  • SpO2 is typically <92%, often requiring ABG.
  • ABG may show hypoxia and normal CO2 (indicating respiratory fatigue).
  • Requires immediate and aggressive intervention, potentially including intubation.
• Near Fatal Asthma: Indicated by a raised PaCO2 (>6 kPa) or the need for assisted ventilation (intubation).

3. Additional Interventions for Resistant or Severe Cases:

• Magnesium Sulfate: A bronchodilator used for life-threatening/near-fatal asthma or poor response to inhaled therapy.
  • Adults: 1.2-2g IV infusion over 20 minutes.
  • Children: Can be given via nebulizer.
• Aminophylline Infusion: Used in desperate, life-threatening, or near-fatal asthma.
  • Loading dose: 5 mg/kg over 20 minutes.
  • Maintenance dose: 0.5 mg/kg/hour.
  • Caution: Should not be given as a bolus to patients already on theophylline. Has significant side effects like arrhythmias and vomiting.
• Adrenaline (Epinephrine): Can be used in desperate cases or for life-threatening asthma.
  • Dose: 0.5 mg IM (1:1000 solution), similar to anaphylaxis.
  • Can be repeated once or twice.
  • It can lead to dramatic bronchodilation.
• Intubation: Considered for patients with severe respiratory failure, exhaustion, coma, worsening hypoxia/hypercapnia, acidosis, or those requiring mechanical ventilation. Non-invasive ventilation (CPAP/BiPAP) is generally not recommended due to risk of air trapping.

4. Investigations:

• Peak Expiratory Flow Rate (PEFR): To assess severity and monitor response to treatment, comparing to the patient's best or predicted value.
• Arterial Blood Gas (ABG): Crucial if SpO2 is <92%, to assess for hypoxia and CO2 levels (normal or elevated CO2 in severe asthma indicates impending respiratory failure).
• Chest Radiograph: Not routine, indicated if pneumonia, pneumothorax, or consolidation is suspected, especially if the patient is not improving or has concurrent symptoms like fever and purulent sputum.

5. Discharge Planning:

• Criteria: PEFR >50% of best/predicted, improvement in symptoms, response to initial treatment.
• Medications:
  • Oral prednisolone (40-50 mg) for 5 days.
  • Inhaled bronchodilators (e.g., salbutamol).
  • Inhaled steroid (e.g., budesonide).
• Education: Check inhaler technique before discharge.
• Follow-up: Arrange referral to respiratory medicine within 48 hours.

6. Intensive Care Referral:

• Indicated for patients not responding to treatment, those with deteriorating PEFR, worsening hypoxia, hypercapnia, acidosis, drowsiness, confusion, or coma. These patients may require intubation and admission to the ICU.