Some Causes of Acute* Dyspnea

Pulmonary causes

Asthma, bronchospasm, or reactive airway disease

Wheezing and poor air exchange that arise spontaneously or after exposure to specific stimuli (eg, allergen, URI, cold, exercise)

Possibly pulsus paradoxus

Often a preexisting history of reactive airway disease

History and physical examination

Sometimes pulmonary function testing or peak flow measurement

Foreign body inhalation

Sudden onset of cough or stridor in a patient (typically an infant or young child) without URI or constitutional symptoms

Inspiratory and expiratory chest radiographs

Sometimes bronchoscopy

Pneumothorax

Abrupt onset of sharp chest pain, tachypnea, diminished breath sounds, and hyperresonance to percussion

May follow injury or occur spontaneously (especially in tall, thin patients and in patients with COPD)

Chest radiograph

Pulmonary embolism

Abrupt onset of sharp chest pain, tachypnea, and tachycardia

Often risk factors for pulmonary embolism (eg, cancer, immobilization, DVT, pregnancy, use of oral contraceptives or other estrogen-containing medications, recent surgery or hospitalization, family history)

CT angiography

Less often, V/Q scanning and possibly pulmonary arteriography

Toxin-induced airway damage (eg, due to inhalation of chlorine or hydrogen sulfide)

Sudden onset after occupational exposure or inappropriate use of cleaning agents

Inhalation usually obvious by history

Chest radiograph

Sometimes ABG measurement and observation to determine severity

Cardiac causes

Acute myocardial ischemia or infarction

Substernal chest pressure or pain that may or may not radiate to the arm or jaw, particularly in patients with risk factors for CAD

ECG

Cardiac enzyme testing

Papillary muscle dysfunction or rupture

Sudden onset of chest pain, new or loud holosystolic murmur, and signs of heart failure, particularly in patients with recent MI

History and physical examination

Echocardiography

Other causes

Anxiety disorder causing hyperventilation

Situational dyspnea often accompanied by psychomotor agitation and paresthesias in the fingers or around the mouth

Normal examination findings and pulse oximetry measurements

History and physical examination

Diagnosis of exclusion

Acute diaphragmatic paralysis

Often sudden onset after trauma affecting the phrenic nerve‡

Frequent orthopnea

Chest radiograph

Fluoroscopic sniff test