Sputum usually occurs in the case of airway inflammation or pneumonia, pink foamy sputum for acute left heart failure, acute pulmonary edema, acute left heart failure, the patient suddenly severe dyspnea, sweating, fear, a sense of imminent death, accompanied by coughing white foamy sputum, cough pink foamy sputum in severe cases. Because of the increased hydrostatic pressure of the capillaries in heart failure, hemoglobin leaks out of the blood vessels, coughed up by the lungs is pink foamy sputum. Meanwhile, Streptococcus pneumoniae infection can cough up rust-colored sputum, Klebsiella infection is brick-red jelly-like sputum, and S. aureus infection is pink milky sputum, which should be differentiated.