The cause of sudden death in pulmonary edema is mainly the accumulation of large amounts of fluid in the interstitium and alveoli of the lungs, which leads to severe diffusion impairment causing hypoxemia and triggering sudden death. In pulmonary edema, plasma colloid osmotic pressure decreases, pulmonary capillary permeability increases, and tissue interstitial pressure increases, resulting in interstitial fluid not being absorbed by pulmonary blood vessels and lymphatic vessels, and a large amount of fluid accumulates in the interstitium and alveoli of the lungs, leading to severe diffusion impairment and hypoxemia and respiratory acidosis, which leads to sudden death. After the development of pulmonary edema to the alveolar edema stage, the patient manifests pale face, severe dyspnea, cold sweat, cyanosis of lips and nail beds, and a large amount of pink foamy sputum. If not timely to the hospital for treatment, may cause sudden death.