Which symptom is a strong indicator of pulmonary edema?

Difficulty breathing while lying down, known as orthopnea, is a hallmark symptom of pulmonary edema. This condition occurs when excess fluid accumulates in the lungs, making it difficult for a person to breathe comfortably in a supine position. When an individual lies down, the redistribution of fluid exacerbates the pulmonary congestion, leading to increased shortness of breath.

In contrast, while swollen feet and ankles can indicate fluid retention related to heart failure or other conditions, they are not specific to pulmonary edema itself. Severe chest pain is more indicative of cardiac ischemia or other acute coronary conditions rather than edema. Lastly, a dry, nonproductive cough can occur in various respiratory conditions, but it does not specifically distinguish pulmonary edema, where a cough is often productive and sometimes associated with a foamy discharge due to the fluid in the lungs. Thus, difficulty breathing while lying down stands out as the most direct and indicative symptom of pulmonary edema.