What is the typical presentation, differential diagnosis (DDX), investigations (INVX), management (MX), and potential complications of an exacerbation of asthma?

Asthma Exacerbation: Presentation, Diagnosis, Management, and Complications

Asthma exacerbations are acute or subacute episodes of progressively worsening shortness of breath, coughing, wheezing, and chest tightness that require prompt recognition and treatment to prevent significant morbidity and mortality. 1

Typical Presentation (Signs and Symptoms)

Common Symptoms

• Breathlessness
• Coughing
• Wheezing
• Chest tightness
• Inability to speak in complete sentences or phrases (in moderate to severe cases)

Physical Signs

• Agitation
• Increased respiratory rate
• Increased pulse rate
• Use of accessory respiratory muscles
• Decreased lung function (measured by FEV1 or PEF)
• Hypoxemia (decreased SaO2)
• Altered mental status (in severe cases)
• Silent chest (absence of wheezing due to severe airflow limitation - life-threatening sign)

Severity Classification

Exacerbations are classified as mild, moderate, severe, or life-threatening based on:

1. Mild:

   • Dyspnea only with activity
   • FEV1 or PEF >70% predicted
   • Normal oxygen saturation

2. Moderate:

   • Dyspnea interferes with usual activities
   • FEV1 or PEF 40-69% predicted
   • Increased respiratory rate

3. Severe:

   • Dyspnea at rest
   • FEV1 or PEF <40% predicted
   • Elevated respiratory and heart rates
   • Use of accessory muscles
   • Oxygen saturation <90%

4. Life-threatening:

   • Drowsiness, confusion
   • Silent chest
   • Cyanosis
   • Poor respiratory effort
   • Bradycardia
   • Hypotension 2

Differential Diagnosis (DDX)

• Chronic Obstructive Pulmonary Disease (COPD)
• Vocal cord dysfunction ("pseudo-asthma")
• Upper airway obstruction
• Foreign body aspiration
• Pulmonary embolism
• Pneumonia
• Congestive heart failure
• Anaphylaxis
• Bronchiectasis
• Eosinophilic pneumonia
• Hyperventilation syndrome/panic attack 3

Investigations (INVX)

Initial Assessment

• Peak expiratory flow (PEF) or FEV1 measurement
• Oxygen saturation (pulse oximetry)
• Arterial blood gas (in severe cases)
• Chest X-ray (to rule out pneumonia, pneumothorax)
• Complete blood count (to identify infection)
• Electrolytes and glucose levels

Serial Measurements

• PEF or FEV1 15-30 minutes after starting treatment and after each subsequent dose
• Continuous oxygen saturation monitoring
• Repeated clinical assessments of respiratory rate, heart rate, and accessory muscle use 2

Management (MX)

Immediate Treatment

1. Oxygen: Administer to maintain SpO₂ >90% (>95% in pregnant women and patients with heart disease)

2. Short-acting beta-2-agonists (SABAs):

   • Mild exacerbations: Albuterol/salbutamol 2-4 puffs via MDI with spacer every 20 minutes for the first hour
   • Moderate to severe: Albuterol 2.5-5 mg nebulized or 4-8 puffs via MDI with spacer every 20 minutes for 3 doses, then 2.5-10 mg every 1-4 hours as needed
   • Severe exacerbations: Consider continuous nebulization at 10-15 mg/hour 2, 4

3. Systemic corticosteroids:

   • Adults: Oral prednisolone 40-60 mg daily for 5-10 days
   • Children: Prednisolone 1-2 mg/kg/day (maximum 60 mg) for 3-10 days
   • IV alternative: Hydrocortisone 200 mg every 6 hours for seriously ill patients 2, 5

4. Adjunct therapies:

   • Ipratropium bromide: 0.5 mg nebulized or 8 puffs via MDI every 20 minutes for 3 doses, then as needed (for severe exacerbations)
   • IV magnesium sulfate: 2 g over 20 minutes for severe exacerbations not responding to initial treatment 2

Monitoring Response

• Measure PEF 15-30 minutes after starting treatment and thereafter according to response
• Monitor clinical improvement in symptoms, respiratory rate, and oxygen saturation
• Continue treatment until PEF reaches 70% of predicted or personal best 2

Hospital Admission Criteria

• Incomplete response to therapy
• Persistent symptoms despite treatment
• Risk factors for asthma-related death:
  • Previous severe exacerbation requiring intubation/ICU
  • Frequent hospitalizations or ED visits
  • High SABA use
  • Difficulty perceiving airway obstruction
  • Psychosocial issues/comorbidities 1, 2

ICU Admission Criteria

• Failure to respond to initial emergency therapy
• Persistent or worsening hypoxemia
• Hypercapnia
• Altered mental status
• Impending respiratory arrest 2

Discharge Criteria

• FEV1 or PEF ≥70% of predicted/personal best
• Minimal or absent symptoms
• Stable response to bronchodilator therapy for 60 minutes 2

Complications

1. Respiratory failure requiring mechanical ventilation
2. Pneumothorax due to air trapping and increased intrathoracic pressure
3. Pneumomediastinum
4. Atelectasis
5. Respiratory infections (secondary bacterial pneumonia)
6. Dehydration from increased respiratory rate and decreased oral intake
7. Metabolic disturbances (hypokalemia from beta-agonist therapy)
8. Cardiac complications (tachyarrhythmias, myocardial ischemia)
9. Steroid-related complications with prolonged use
10. Death - approximately 1 in 250 deaths globally are attributed to asthma 6

Prevention of Future Exacerbations

• Provide written asthma action plan
• Review and optimize inhaler technique
• Consider stepping up maintenance therapy
• Identify and address triggers and comorbidities
• Schedule follow-up appointment within 1 week
• Continue or initiate inhaled corticosteroids 2, 7

Special Considerations

• Paradoxical bronchospasm: Can occur with inhaled beta-agonists and be life-threatening; discontinue immediately if suspected 4
• Corticosteroid tapering: Not necessary for courses less than 1 week 2
• MDI vs. nebulizer: MDI with spacer can be as effective as nebulized medications for delivering bronchodilators 2
• NSAID sensitivity: Patients with confirmed Aspirin-Exacerbated Respiratory Disease (AERD) should avoid all traditional NSAIDs 2
• Brittle asthma: Some patients have unpredictable instability requiring specialized management 3

Remember that early treatment of asthma exacerbations is the best strategy for management, and proper patient education is crucial to prevent future episodes.