Differential

Dyspnea is a distressing breathing sensation, not a diagnosis. The patient may describe air hunger, chest tightness, increased effort, or an inability to get enough air; these descriptions reflect different parts of the same respiratory control system. Breathlessness develops when respiratory drive exceeds what the lungs, airways, circulation, muscles, or metabolic system can achieve. Increased work of breathing, impaired gas exchange, and increased ventilatory demand can each create that mismatch. The same symptom may therefore arise from asthma, heart failure, pulmonary embolism, anemia, or severe metabolic acidosis. Organize the differential into four working groups: - Cardiac: heart failure, ischemia, valvular disease, and arrhythmia. - Pulmonary: asthma, COPD, pneumonia, interstitial lung disease, and pleural disease. - Vascular: pulmonary embolism and pulmonary hypertension. - Non-cardiopulmonary: anemia, obesity, deconditioning, anxiety, neuromuscular weakness, and metabolic acidosis. Time course changes priority. Sudden dyspnea over minutes to hours raises concern for pulmonary embolism, pneumothorax, anaphylaxis, acute pulmonary edema, arrhythmia, or acute coronary syndrome. A gradually progressive symptom over weeks to months makes chronic airway disease, heart failure, anemia, interstitial disease, malignancy, obesity, and deconditioning more likely,...