Clinical meaning
Asthma is chronic inflammatory disease driven by Th2 immune response producing IL-4 (IgE switching), IL-5 (eosinophil recruitment), IL-13 (mucus, hyperresponsiveness). IgE cross-linking triggers mast cell degranulation. Stepwise therapy: Step 1-2 = PRN ICS-formoterol; Step 3 = low-dose ICS-LABA; Step 4-5 = medium-high ICS-LABA +/- LAMA +/- biologic.
Diagnosis & workup
Diagnostics & workup: - Sputum culture, Gram stain, and AFB stain - ABG: pH, PaCO2, PaO2, HCO3, A-a gradient calculation - Chest X-ray PA and lateral (infiltrates, hyperinflation, effusions) - D-dimer (high sensitivity, low specificity for PE) - Peak expiratory flow rate monitoring for asthma - Procalcitonin for bacterial vs viral pneumonia differentiation - Bronchoscopy with BAL for diagnostic sampling
Risk factors: - Immunocompromised state increasing pneumonia susceptibility - Occupational dust/chemical exposure (asbestos, silica, coal) - Indoor air pollution and biomass fuel exposure - GERD with chronic microaspiration - Age >65 with declining mucociliary clearance - Cystic fibrosis genotype (CFTR mutations) - Environmental allergen sensitization (dust mites, mold, pollen)