Although most asthmatic attacks are mild and reversible, severe attacks can be fatal and many patients develop chronic airflow limitation from permanent airway remodeling. Asthma is the most common chronic disease of childhood, while chronic obstructive pulmonary disease (COPD) is a leading cause of death in the world. COPD is the only major cause of death that is increasing in frequency, a phenomenon attributed to tobacco abuse. The prevalence has been stable in men, whereas the prevalence in women has doubled in the past few decades and women now account for >50% of COPD-related deaths.
Asthma is a chronic inflammatory disorder associated with hyperresponsiveness of the tracheobronchial tree and a continuum of acute bronchospasm and airway inflammation. COPD has two dominant forms: (a) pulmonary emphysema, defined in terms of anatomic pathology, characterized by destruction of bronchioles and alveoli and (b) chronic bronchitis, defined in clinical terms as a condition of excess mucous secretion in the bronchial tree, with a chronic productive cough for 3 months in each of two consecutive years. The World Health Organization's Global Institute for Chronic Obstructive Lung Disease definition of COPD encompasses both these forms as well as bronchiectasis, and asthma, and recognizes that most patients have a combination.
Acute exacerbations of asthma and COPD are usually associated with a trigger, such as smoking, respiratory infections, exposure to noxious stimuli (e.g., pollutants, cold, stress, antigens, or exercise), adverse response to medications (e.g., decongestants, β-blockers, nonsteroidal anti-inflammatory drugs), allergic reactions, hormonal changes during the normal menstrual cycle or pregnancy, and noncompliance with prescribed therapies. Although asthma exacerbations are due to expiratory airflow limitations, acute exacerbations of COPD are primarily due to ventilation–perfusion mismatch.
Classically, patients with exacerbations of asthma or COPD present with complaints of dyspnea, chest tightness, wheezing, and cough. Risk factors for death from asthma exacerbation include past history of severe exacerbation, ≥2 hospitalizations or >3 ED visits for asthma in the past year, >2 canisters per month of inhaled short-acting β2 agonist (SABA), low socioeconomic status or history of illicit drug use, or psychiatric disease. Physical examination shows wheezing with prolonged expiration. Wheezing does not correlate with the degree of airflow obstruction; a “quiet chest” may indicate severe airflow restriction. Patients with severe attacks may be sitting upright with forward posturing, with pursed-lip exhalation, accessory muscle use, paradoxical respirations, and diaphoresis. Pulsus paradoxus of 20 mm Hg or higher may be seen. Severe airflow obstruction and ventilation/perfusion imbalance can cause hypoxia and hypercapnia. Hypoxia is characterized by tachypnea, cyanosis, agitation, apprehension, tachycardia, and hypertension. Signs of hypercapnia include confusion, tremor, plethora, stupor, hypopnea, and apnea. Impending respiratory failure may be signaled by alteration in mental status, lethargy, minimal or absent breath sounds, acidosis, worsening hypoxia, and hypercapnia.
DIAGNOSIS AND DIFFERENTIAL
Emergency department diagnosis of asthma or COPD usually is made clinically, although signs ...