Asthma Lecture Notes

Introduction

• Video by Ninja Nerd on clinical medicine focusing on asthma.
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Overview of Asthma

• Asthma is an obstructive lung disease characterized by recurring symptoms, airflow obstruction, bronchial hyperresponsiveness, and underlying inflammation.
• Common Symptoms:
  • Dyspnea (shortness of breath)
  • Wheezing
  • Hyper-resonance to percussion
  • Cough

Pathophysiology

• Bronchial Wall Edema:
  • Inflammation in bronchial walls leads to narrowing airway.
  • Causes difficulty in getting CO2 out and O2 in.
• Mucus Production:
  • Goblet cells secrete excessive mucus due to inflammation.
  • Contributes to airway narrowing.
• Bronchospasm:
  • Smooth muscle contraction in bronchial walls further obstructs airflow.

Mechanisms Leading to Airway Obstruction

1. Increased Wall Edema and Mucus Production:
   • Often triggered by allergens, infections, medications (e.g., aspirin sensitivity), cold air, and exercise.
2. Atopic Triad:
   • Includes allergies, atopic dermatitis, and asthma.
3. Airway Inflammation and Obstruction:
   • Leads to air trapping, hyperinflation, and severe obstruction.

Complications of Asthma

• Respiratory Failure:
  • Severe cases may lead to status asthmaticus.
  • CO2 retention (hypercapnia) and reduced O2 intake (hypoxia) are critical issues.
• Type 2 Respiratory Failure:
  • Characterized by high CO2 and low O2.
• Potential for Pneumothorax:
  • Due to hyperinflation, risk of lung rupture is increased.

Diagnostic Approach

• Initial tests: Chest x-ray, ECG, and ABG.
• Pulmonary Function Tests (PFTs):
  • FEV1/FVC Ratio: Less than 70% indicates obstructive disease.
  • Reversibility Test: Administer bronchodilator and check FEV1 improvement.
• Peak Expiratory Flow Rate:
  • To assess exacerbation severity and treatment response.

Treatment

• General Management:
  • Bronchodilators: Short-acting beta 2 agonists (e.g., albuterol).
  • Anti-inflammatory: Corticosteroids.
  • Leukotriene Antagonists: Useful in specific scenarios like aspirin-induced asthma.
• Stepwise Asthma Treatment:
  • Based on frequency of symptoms and PFT results.
  • Ranges from intermittent to persistent asthma management.
• Management of Acute Exacerbations:
  • Use of duonebs (beta 2 agonists and muscarinic blockers), systemic steroids, BiPAP or ventilation if necessary.
  • Additional interventions like IV magnesium and ketamine (both a bronchodilator and anxiolytic).

Conclusion

• Understanding asthma involves recognizing symptoms, pathophysiology, potential complications, and appropriate treatment protocols.
• Effective management requires a combination of medication, monitoring, and occasionally, emergency interventions.