Dyspnea on exertion differentials
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I now have comprehensive material from Harrison's (dedicated dyspnea chapter) and Rosen's Emergency Medicine. Here is the full differential:
Dyspnea on Exertion — Differential Diagnosis
Dyspnea on exertion (DOE) is breathlessness provoked by physical effort. Pulmonary and cardiac etiologies account for ~85% of chronic dyspnea cases. The differential spans multiple systems, organized below by urgency and category.
Cardiac Causes
| Condition | Key Features |
|---|---|
| Heart failure (systolic or diastolic) | Most common; orthopnea, PND, S3 gallop, elevated BNP |
| Myocardial infarction / ischemia | DOE as anginal equivalent; especially in diabetics/elderly women |
| Valvular heart disease | Aortic stenosis (exertional syncope triad), mitral stenosis/regurgitation |
| Cardiomyopathy | Dilated, hypertrophic (HCM — exertional DOE ± syncope), restrictive |
| Cardiac tamponade | Elevated JVP, pulsus paradoxus, muffled sounds |
| Pulmonary arterial hypertension | Right heart strain; consider in HIV, CTD, chronic liver disease |
| Arrhythmia | Palpitations + DOE; AF, SVT, heart block |
| Congenital heart disease | In younger patients; shunts, uncorrected lesions |
Pulmonary Causes
| Condition | Key Features |
|---|---|
| COPD | Chronic progressive DOE; smoking history; obstructive pattern on PFTs |
| Asthma | Variable airflow obstruction; wheezing, chest tightness; worse with exercise/cold air |
| Interstitial lung disease (ILD/IPF) | Bibasilar crackles, restrictive pattern, GGOs on HRCT |
| Pulmonary embolism (PE) | Acute DOE; tachycardia, hypoxia, pleuritic chest pain; risk factors (DVT, immobility, malignancy) |
| Pulmonary hypertension | Exertional DOE, fatigue, syncope; right heart strain on ECG/echo |
| Pleural effusion | Dullness to percussion, reduced breath sounds at base |
| Pneumonia | Infectious prodrome, fever, consolidation on CXR |
| Pneumothorax | Sudden onset; may be exertional in young tall males (spontaneous); absent breath sounds |
| Upper airway obstruction | Stridor, monophonic wheeze; neoplasm, foreign body, tracheal stenosis |
| Obesity hypoventilation / sleep apnea | BMI >30, daytime somnolence, hypercapnia |
| Cor pulmonale | RV failure secondary to lung disease |
Cardiovascular Overlap
| Condition | Notes |
|---|---|
| Deconditioning | Extremely common; diagnosis of exclusion; normal workup |
| Anemia | High-output state; pallor, tachycardia, reduced Hgb |
| Pulmonary edema (cardiogenic or non-cardiogenic/ARDS) | Bilateral crackles, hypoxia, frothy sputum |
Metabolic / Hematologic
| Condition | Notes |
|---|---|
| Anemia | Fatigue, pallor; low Hgb/Hct |
| Metabolic acidosis | Compensatory tachypnea (Kussmaul breathing); check electrolytes, lactate, ABG |
| Hyperthyroidism | High-output cardiac state; tremor, weight loss, palpitations |
| Obesity | Increased work of breathing; often multifactorial |
Neuromuscular
| Condition | Notes |
|---|---|
| Myasthenia gravis | Fatigable weakness; bulbar symptoms |
| ALS / diaphragm weakness | Orthopnea in recumbency (paradoxical — worse lying flat due to diaphragm); FVC reduced |
| Guillain-Barré | Ascending weakness + DOE |
| Myopathies | Inflammatory (dermatomyositis, polymyositis) or hereditary |
Psychiatric
| Condition | Notes |
|---|---|
| Panic disorder / anxiety | Diagnosis of exclusion; hyperventilation syndrome; normal O₂ sat |
| Somatization | Chronic, variable; discordant exam |
Approach by Onset
| Onset | Think... |
|---|---|
| Acute | PE, pneumothorax, acute MI, acute HF exacerbation, anaphylaxis, arrhythmia |
| Subacute | Pneumonia, pericarditis, pleural effusion |
| Chronic / progressive | COPD, ILD, HF, valvular disease, PAH, anemia, deconditioning |
Diagnostic Anchors
- Orthopnea + PND → Heart failure
- Exertional syncope or systolic murmur → HCM or aortic stenosis
- Pleuritic chest pain + risk factors → PE
- Bibasilar crackles + clubbing → ILD
- Wheezing + reversibility → Asthma
- Hypoxia disproportionate to symptoms → Shunt, PE, ILD
- Normal workup → Deconditioning, anxiety, anemia
Sources: Harrison's Principles of Internal Medicine 22E, Ch. 39 (Dyspnea) — p. 311; Rosen's Emergency Medicine, Ch. 21 (Dyspnea) — Table 21.1; Fishman's Pulmonary Diseases, Ch. 32 (Unexplained Dyspnea)
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