Introduction
Dyspnea, or shortness of breath, is a common clinical symptom that can arise from respiratory, cardiac, metabolic, or neuromuscular conditions. A structured approach is essential for timely diagnosis and management. This guide follows a systematic framework based on Harrison’s Principles of Internal Medicine to evaluate dyspnea effectively.
Step 1: History and Initial Assessment
Onset: Acute (<48 hours), subacute, or chronic (>4 weeks).
Progression: Sudden, intermittent, or progressive.
Exacerbating/Relieving Factors: Exertion, lying flat (orthopnea), seasonal changes, medications.
Associated Symptoms:
Chest pain → Suspect cardiac ischemia, pulmonary embolism.
Fever, cough → Consider pneumonia, bronchitis.
Wheezing → Asthma, COPD.
Peripheral edema → Heart failure.
Stridor → Upper airway obstruction.
Hemoptysis → Pulmonary embolism, tuberculosis, malignancy.
Weight loss → Cancer, chronic infections.
Risk Factors: Smoking, occupational exposure, travel history, recent surgery, known lung or heart disease.
Step 2: Physical Examination
1. General Examination
Respiratory Rate & Pattern: Tachypnea, bradypnea, Kussmaul’s breathing (metabolic acidosis), Cheyne-Stokes breathing (heart failure, brain injury).
Use of Accessory Muscles: Indicates increased work of breathing.
Cyanosis: Central (hypoxemia) vs. peripheral (circulatory issues).
Jugular Venous Pressure (JVP): Elevated in heart failure, pulmonary hypertension.
2. Respiratory Examination
Inspection: Barrel chest (COPD), tracheal deviation (pneumothorax).
Percussion:
Dullness → Pleural effusion, pneumonia.
Hyperresonance → Pneumothorax, COPD.
Auscultation:
Wheezing → Asthma, COPD.
Crackles → Pulmonary edema, pneumonia, ILD.
Absent breath sounds → Pneumothorax, massive effusion.
3. Cardiovascular Examination
Murmurs: Valvular heart disease.
Third heart sound (S3): Heart failure.
Pulsus paradoxus: Severe asthma, cardiac tamponade.
Step 3: Initial Investigations
Step 4: Differential Diagnosis Based on Time Course
1. Acute Dyspnea (<48 hours)
Cardiac Causes: Pulmonary edema, acute MI, cardiac tamponade.
Respiratory Causes: Pulmonary embolism, pneumothorax, pneumonia, airway obstruction, ARDS.
Metabolic Causes: Diabetic ketoacidosis (DKA), metabolic acidosis.
Neuromuscular Causes: Guillain-Barré syndrome, myasthenia crisis.
2. Chronic Dyspnea (>4 weeks)
Respiratory: COPD, asthma, interstitial lung disease (ILD), bronchiectasis.
Cardiac: Heart failure, pulmonary hypertension.
Hematologic: Anemia.
Psychogenic: Anxiety, hyperventilation syndrome.
Step 5: Management Approach
1. Emergency Management (If Life-Threatening Dyspnea)
High-flow oxygen or ventilatory support (CPAP/BiPAP or intubation).
Treat underlying cause:
Bronchodilators, steroids for asthma/COPD exacerbation.
Diuretics, vasodilators for heart failure.
Thrombolysis/anticoagulation for PE.
Antibiotics for pneumonia.
Chest tube for pneumothorax.
2. Long-Term Management Based on Diagnosis
Asthma/COPD: Inhalers (SABA, LABA, ICS), pulmonary rehabilitation.
Heart failure: Diuretics, ACE inhibitors, beta-blockers.
ILD: Immunosuppressants, antifibrotics, oxygen therapy.
Pulmonary hypertension: Vasodilators (prostacyclin analogs, PDE-5 inhibitors).