Asthma (Obstructive Disease)
• Inflammatory condition of the airways
• hyperresponsiveness leading to airway edema + bronchoconstriction
• Recurrent/intermittent episodes of wheezing, shortness of breath, and/or cough
• Usually reversible either spontaneously or with treatment.
Atopy (IgE mediated) + Environmental triggers (allergens, irritants, chemicals, respiratory infections, physical stress, and emotional stress).
Reversible bronchoconstriction on own or with bronchodilator and a history. Consider challenge test
Intermittent, mild persistent, moderate persistent, and severe persistent
• GERD, Allergic rhinitis
• Worsened by Allergic bronchopulmonary aspergillosis (ABPA), Obstructive sleep apnea-hypopnea (OSA), Stress
• Normal if no active disease.
• FEV1/FVC < 70%
• Decreased expiratory flow
• Significant response to beta2-agonist.
• Normal or increased TLC (due to hyperinflation).
• Normal or reduced VC.
• DLCO is normal.
Exercise induced bronchospasm
Decrease in FEV1 of >10% on a treadmill or a stationary bicycle.
Normal in mild cases. Severe asthma shows hyperinflation.
Arterial Blood Gas
• Indicated in respiratory distress.
• Hypocarbia from hyperventilation.
• Hypoxemia may be present.
• If CO2 level is normal or high sign that the patient is decompensating due to fatigue or severe airway obstruction and intubation may be required.
•Methacholine challenge, histamine challenge, and thermal (cold air). Principle of nonspecific hyperirritability.
•Must both tighten up with the challenge and loosen up with subsequent bronchodilators.
• Response to short-acting bronchodilator (increase in the FEV1 > 12% and increase of 200 mL).
Quick relief (acute, mild, intermittent disease)
• Short-acting beta2-agonists (SABAs)
• Systemic corticosteroids
• Inhaled corticosteroids (ICS; most potent and most effective)
• Long-acting beta2-agonists (LABAs)
• Mast-cell stabilizers (cromolyn sodium +nedocromil)
• Leukotriene modifiers
• Methylxanthines (theophylline) • Immunomodulators (omalizumab = anti-IgE)
• Inhaled B agonist and ipratropium via nebulizer or MDI. Assess response clinically and with peak flow.
• IV or oral corticosteroids, then taper when improvement occurs.
• Third-line agents include IV magnesium, which helps with bronchospasm in severe refractory cases.
• Supplemental oxygen to keep Osat>90%. Antibiotics if necessary. Intubation for respiratory failure.
• Symptoms <2 times per week, nighttime awakenings <2x per month.
• Normal baseline FEV1 and FEV1/FVC.
• Needs no long-term control medications, just short acting beta agonist (albuterol).
• Symptoms >2 times per week but not every day. 3-4 nighttime awakenings per month, minor limitations on activities.
• Normal PFTs.
• Low dose inhaled corticosteroid indicated with PRN albuterol inhaler.
• Daily symptoms with frequent exacerbations.
• FEV1 is 60-80% of expected.
• Daily inhaled low dose corticosteroid, PRN albuterol inhaler, and LABA inhaler. +/- cromolyn/methylxanthine/antileukotriene.
• Continual symptoms with frequent exacerbations and limited physical activity.
• FEV1 <60% of predicted.
• Daily high dose inhaled corticosteroid, PRN albuterol, and long-acting beta agonists. +/- methylxanthine and systemic corticosteroids.
Treatment and Maintenance
Differential Diagnosis of Wheezing
• CHF: due to edema of airways and congestion of bronchial mucosa.
• COPD: inflamed airways may be narrowed or bronchospasm may be present.
• Asthma: most common cause.
• Cardiomyopathy/Pericarditis: can lead to edema around the bronchi.
• Lung Cancer: due to obstruction of airways (central tumor or mediastinal invasion).