MANAGEMENT OF LOWER AIRWAY OBSTRUCTION

Lower airway obstruction impairs airflow to the lungs, leading to increased work of breathing, hypoxia, and potential respiratory failure if not managed appropriately. It commonly occurs in conditions such as asthma and bronchiolitis, which narrow or block the lower airways due to inflammation, mucus production, or bronchospasm.

Key Goals of Management:
Relieve airway obstruction by reducing inflammation and bronchospasm.
Improve oxygenation and ventilation to prevent respiratory failure.
Provide supportive care tailored to the underlying cause.

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ASTHMA MANAGEMENT

Asthma is a chronic inflammatory airway disease that leads to bronchospasm, airway edema, and increased mucus production, causing reversible airflow obstruction.

Signs of Lower Airway Obstruction in Asthma:

• Expiratory wheezing (hallmark sign)
• Prolonged expiratory phase
• Tachypnea and increased work of breathing (retractions, nasal flaring)
• Coughing fits (especially at night or after exertion)
• Severe cases: Silent chest (no air movement), cyanosis, altered mental status → Impending respiratory failure!

Treatment Approach for Pediatric Asthma:

Mild to Moderate Asthma Exacerbation

Nebulized Albuterol (β₂-agonist): 2.5 mg every 20 minutes as needed (can be given via MDI with spacer).
Ipratropium Bromide (Anticholinergic): 500 mcg every 20 minutes for 3 doses (used in moderate/severe cases).
Systemic Corticosteroids:

• Prednisone or prednisolone: 1-2 mg/kg PO (max 60 mg)
• Dexamethasone: 0.6 mg/kg PO/IV (single dose, max 16 mg)

Severe Asthma Exacerbation

Continuous Albuterol Nebulization (10-15 mg/hour via nebulizer).
Magnesium Sulfate (IV): 25-50 mg/kg IV over 20 minutes (max 2 g) to relax bronchial smooth muscle.
Subcutaneous or IM Epinephrine: 0.01 mg/kg of 1:1000 solution (max 0.3 mg) if severe bronchospasm.
Consider Non-Invasive Ventilation (BiPAP/CPAP) for severe respiratory distress.

When to Intubate?

• Severe respiratory fatigue, altered mental status, silent chest.
• Persistent hypoxia despite maximal therapy.

Key Clinical Pearls:
Nebulized bronchodilators and steroids are first-line treatment.
If worsening, consider magnesium sulfate or epinephrine.
Avoid intubation unless absolutely necessary—positive pressure ventilation can worsen air trapping.

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BRONCHIOLITIS MANAGEMENT

Bronchiolitis is a viral lower respiratory tract infection (commonly caused by RSV) that leads to inflammation, mucus plugging, and airway obstruction, particularly in infants and young children.

Signs of Bronchiolitis:

• Diffuse wheezing and crackles
• Nasal congestion and rhinorrhea (precedes lower airway symptoms)
• Tachypnea with retractions
• Hypoxia (SpO₂ < 90%) in severe cases
• Apnea in high-risk infants (especially preterm babies and those <3 months old)

Treatment Approach for Pediatric Bronchiolitis:

Mild Cases (Supportive Care at Home)

Nasal suctioning to clear secretions.
Hydration and feeding support (small frequent feeds to prevent dehydration).
Monitor for worsening symptoms (increased work of breathing, poor feeding, lethargy).

Moderate to Severe Cases (Hospital Management)

Oxygen Therapy: If SpO₂ < 90%, provide humidified oxygen via nasal cannula.
High-Flow Nasal Cannula (HFNC):

• Used for moderate to severe respiratory distress.
• Provides positive airway pressure to reduce work of breathing.
  Trial of Nebulized Hypertonic Saline (3%) to help reduce mucus plugging (not routinely recommended but may help select cases).

What NOT to Use in Bronchiolitis (Not Recommended by Guidelines)

Albuterol or nebulized epinephrine (not effective unless history of asthma).
Systemic corticosteroids (not beneficial for viral bronchiolitis).
Antibiotics (only needed if secondary bacterial infection is suspected).

When to Intubate?

• Severe hypoxia despite HFNC or CPAP.
• Progressive apnea or respiratory fatigue.

Key Clinical Pearls:
Supportive care is the mainstay of treatment.
HFNC improves ventilation in severe cases.
Avoid unnecessary medications (steroids, bronchodilators) unless history suggests asthma.

 

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DIFFERENTIATING ASTHMA VS. BRONCHIOLITIS

SUMMARY: KEY MANAGEMENT STRATEGIES FOR LOWER AIRWAY OBSTRUCTION

Asthma = Airway inflammation + bronchospasm → Use bronchodilators & steroids.
Bronchiolitis = Viral airway inflammation + mucus plugging → Use oxygen & HFNC, avoid steroids.
Early recognition and appropriate intervention prevent respiratory failure and improve outcomes.

Takeaway: Lower airway obstruction can quickly lead to respiratory failure if not managed promptly. Understanding the differences between asthma and bronchiolitis ensures the right treatment approach for each condition.