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For further information, see CMDT Part 2-03: Dyspnea

Key Features

Essentials of Diagnosis

  • Inquire about

    • Fever; cough; risk of infection with SARS-CoV-2; chest pain

    • Vital signs; pulse oximetry

    • Chest and cardiac examination

    • Chest radiography

    • Arterial blood gas result (in selected patients)

General Considerations

  • Defined as a subjective experience or perception of uncomfortable breathing

  • Can result from primary pulmonary vasculopathy (pulmonary hypertension) or from psychogenic conditions or from conditions that

    • Increase the mechanical effort of breathing (eg, asthma, chronic obstructive pulmonary disease [COPD], restrictive lung disease, respiratory muscle weakness)

    • Produce compensatory tachypnea (eg, hypoxemia or acidosis)

  • The following factors play a role in how and when dyspnea presents in patients:

    • Rate of onset

    • Previous dyspnea

    • Medications

    • Comorbidities

    • Psychological profile

    • Severity of underlying disorder

Clinical Findings


  • Rapid onset, severe dyspnea in the absence of other clinical features should raise concern for

    • Pneumothorax

    • Pulmonary emboli

    • Increased left ventricular end-diastolic pressure (LVEDP)

  • Spontaneous pneumothorax

    • Usually accompanied by chest pain

    • Occurs most often in thin, young males, or in those with underlying lung disease

  • Pulmonary emboli should always be suspected when cause of dyspnea is not apparent or when a patient with new dyspnea reports

    • A recent history (previous 4 weeks) of prolonged immobilization or surgery

    • Estrogen therapy

    • Other risk factors of deep venous thrombosis (eg, previous history of thromboembolism, cancer, obesity, lower extremity trauma)

  • Silent myocardial infarction

    • Occurs more frequently in diabetic persons and women

    • Can result in increased LVEDP, acute heart failure (HF), and dyspnea

  • When cough and fever are present,

    • Pulmonary disease (particularly infections) is the primary concern

    • However, myocarditis, pericarditis, and septic pulmonary emboli can also present in this manner

  • Chest pain

    • Should be further characterized as acute or chronic, pleuritic or exertional

    • Although acute pleuritic chest pain is the rule in acute pericarditis and pneumothorax, most patients with pleuritic chest pain in the outpatient clinic have pleurisy due to acute viral respiratory tract infection

    • Periodic chest pain that precedes the onset of dyspnea is suspicious for myocardial ischemia or pulmonary emboli

  • Wheezing

    • Most cases due to acute bronchitis

    • Other causes include new-onset asthma, foreign body, and vocal cord dysfunction

  • Interstitial lung disease and pulmonary hypertension should be considered in patients with symptoms (or history) of connective tissue disease

  • When a patient reports prominent dyspnea with mild or no accompanying features, consider

    • Noncardiopulmonary causes of impaired oxygen delivery (anemia, methemoglobinemia, cyanide ingestion, carbon monoxide)

    • Metabolic acidosis due to a variety of conditions

    • Panic disorder

    • Neuromuscular disorders

    • Chronic pulmonary embolism

  • Platypnea-orthodeoxia syndrome

    • Characterized by dyspnea and hypoxemia on sitting or standing that improves in the recumbent position

    • May be caused by an intracardiac shunt, pulmonary vascular shunt, or ventilation-perfusion mismatch

  • Hyperthyroidism can cause dyspnea from

    • Increased ventilatory drive

    • Respiratory muscle weakness

    • Pulmonary hypertension

  • Infection with SARS-CoV-2 is notable for precipitous increase in dyspnea following ...

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