What is the main cause of pulmonary edema?

The main cause of pulmonary edema is indeed related to increased fluid in the lungs. Pulmonary edema occurs when excess fluid accumulates in the air sacs (alveoli) of the lungs, making it difficult for the body to absorb oxygen. This condition can arise from various underlying issues, most commonly heart-related problems, where the heart's inefficiency leads to increased blood pressure in the pulmonary circulation, forcing fluid out of the capillaries into the alveoli.

While high altitude can lead to high-altitude pulmonary edema, this is less common and typically involves individuals with certain risk factors or conditions. Viral infections can affect lung function but don’t primarily cause pulmonary edema on their own. Obesity may contribute to increased risks for respiratory conditions but does not directly cause pulmonary edema.

By understanding that increased fluid in the lungs is central to the definition and pathophysiology of pulmonary edema, one can appreciate that it represents the fundamental process that leads to the condition, differentiating it from other indirect contributing factors.