Pulmonary edema is the medical term used to refer to the accumulation of fluid in the lungs, specifically in the alveoli or air sacs, according to Medical News Today. It affects gas exchange and makes breathing difficult. It is rarely fatal with prompt and adequate treatment.
According to MedicineNet, edema or swelling happens when the fluid inside blood vessels leaks outside to fill the surrounding tissues. This occurs either because the amount of proteins in the blood is not enough or the pressure within the vessels is high. Since the air sacs have thin walls, these are easily penetrated when either of the triggers is present. For efficient gas exchange, maintaining the integrity of the alveolar walls is vital.