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: - Pulmonary function tests: FEV1, FVC, FEV1/FVC ratio, DLCO - Polysomnography for sleep-disordered breathing - Procalcitonin for bacterial vs viral pneumonia differentiation - CT chest high-resolution for interstitial/parenchymal disease - ABG: pH, PaCO2, PaO2, HCO3, A-a gradient calculation - Pulse oximetry and continuous SpO2 monitoring - Chest X-ray PA and lateral (infiltrates, hyperinflation, effusions)
Risk factors: - Current or former tobacco use (pack-year calculation) - Prior TB exposure or latent TB infection - Cystic fibrosis genotype (CFTR mutations) - Family history of alpha-1 antitrypsin deficiency - Occupational dust/chemical exposure (asbestos, silica, coal) - Obesity with restrictive physiology and OSA - Indoor air pollution and biomass fuel exposure