Pulmonology · Obstructive Lung Disease
The facts most likely to be tested
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The diagnosis of asthma is confirmed by spirometry demonstrating a reversible obstructive pattern, defined as an increase in FEV1 >12% and >200 mL following bronchodilator administration.
GINA guidelines now recommend as-needed low-dose inhaled corticosteroid (ICS)-formoterol as the preferred controller therapy for all severities of asthma to reduce the risk of severe exacerbations.
Methacholine challenge testing is the diagnostic procedure of choice to rule out asthma in patients with normal baseline spirometry but high clinical suspicion.
Pulsus paradoxus (a drop in systolic blood pressure >10 mmHg during inspiration) is a sign of severe asthma exacerbation indicating significant air trapping and increased intrathoracic pressure.
A normal or elevated PaCO2 in a patient presenting with an acute asthma exacerbation is a red flag for impending respiratory failure and requires immediate aggressive intervention.
Asthma-COPD overlap (ACO) is characterized by persistent airflow limitation with features of both asthma and COPD, typically requiring ICS-containing therapy to prevent rapid lung function decline.
Exercise-induced bronchoconstriction is best managed with a short-acting beta-agonist (SABA) or ICS-formoterol taken immediately prior to physical activity.
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A 24-year-old female presents to the urgent care clinic complaining of intermittent wheezing and chest tightness that worsens at night and after running. She reports using an over-the-counter inhaler occasionally with minimal relief. On physical exam, she has bilateral expiratory wheezing and a respiratory rate of 18/min. Spirometry reveals an FEV1/FVC ratio of 0.68, which improves to 0.78 after the administration of albuterol.
What is the most appropriate long-term management strategy for this patient according to current GINA guidelines?
As-needed low-dose ICS-formoterol
The patient demonstrates a reversible obstructive pattern on spirometry consistent with asthma; current guidelines prioritize as-needed ICS-formoterol over SABA-only therapy to reduce the risk of severe exacerbations.
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High yield triage
Etiology / Epidemiology
Chronic inflammatory airway disease driven by atopy and hyperresponsiveness. Common in children with a strong genetic predisposition.
Clinical Manifestations
Triad of wheezing, dyspnea, and cough. Silent chest indicates impending respiratory failure.
Diagnosis
Spirometry showing reversible obstruction (FEV1/FVC <0.70, FEV1 increase >12% post-bronchodilator).
Treatment
Inhaled corticosteroids (ICS) + formoterol (PRN) for mild; SABA for rescue. Avoid monotherapy with LABA.
Prognosis
Most achieve control with adherence. Status asthmaticus is the primary life-threatening complication.
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Epidemiology & Etiology
Asthma is the most common chronic disease of childhood, often associated with the atopic triad (asthma, eczema, allergic rhinitis). Triggers include viral infections, allergens, exercise, and cold air. Adult-onset asthma is more common in females and often linked to occupational exposures.
Pertinent Anatomy
Pathology involves the bronchioles, where smooth muscle hypertrophy and mucosal edema occur. Airway remodeling leads to permanent structural changes in the bronchial walls.
Pathophysiology
Chronic inflammation involves eosinophils, mast cells, and T-helper 2 (Th2) lymphocytes. This leads to bronchoconstriction, mucus hypersecretion, and airway edema. The resulting air trapping causes hyperinflation and increased work of breathing.
Clinical Manifestations
Patients present with episodic wheezing, chest tightness, and non-productive cough, often worse at night. Silent chest and pulsus paradoxus are signs of severe obstruction. Inability to speak in full sentences is a red flag for respiratory distress.
Diagnosis
Spirometry is the gold standard, demonstrating an obstructive pattern. A positive bronchodilator challenge (FEV1 increase ≥12% and ≥200 mL) confirms the diagnosis. Methacholine challenge is used to rule out asthma if spirometry is non-diagnostic.
Treatment
The cornerstone is Inhaled Corticosteroids (ICS) to reduce inflammation. For acute exacerbations, use SABA (albuterol) and systemic corticosteroids. Never use LABA as monotherapy due to increased mortality risk. Use the GINA guidelines for a step-up approach based on symptom frequency.
Prognosis
Most patients maintain normal lung function with proper ICS adherence. Status asthmaticus requires aggressive management with oxygen, nebulized SABA, and systemic steroids. Monitor Peak Expiratory Flow (PEF) for objective home assessment.
Differential Diagnosis
COPD: irreversible obstruction on spirometry
GERD: cough worse when supine, no wheezing
Vocal cord dysfunction: inspiratory stridor, not wheezing
Heart failure: cardiac asthma, elevated BNP, crackles
Foreign body aspiration: sudden onset, unilateral findings