The bronchoalveolar breath sounds are a mixture of bronchial breath sounds and alveolar breath sounds. The nature of inspiratory sounds is similar to normal alveolar breath sounds, but the pitch is higher and louder. The nature of the expiratory sounds is similar to that of bronchial breath sounds, but the intensity is slightly weaker, the pitch is slightly lower, the tube-like nature is less and the expiratory phase is shorter, and there is a very short gap between inspiration and expiration. What is the prevention of bronchoalveolar sounds? Prevention of bronchoalveolar sounds: attention should be paid to the prevention and treatment of chronic infections of the oral cavity and upper respiratory tract to eliminate the chance of accidental inhalation of contaminated secretions into the lower respiratory tract, and for oral and thoracoabdominal surgery cases, careful and meticulous preoperative preparation, intraoperative attention to the depth of anesthesia, timely removal of blood clots and secretions from the oral cavity and respiratory tract, strengthening postoperative oral respiratory care, such as careful use of sedative, analgesic and cough suppressant drugs, attention to the respiratory tract Wetting, diluting secretions, encouraging patients to cough, and keeping the drainage of the respiratory tract unobstructed, so as to effectively prevent respiratory aspiration infection. Alveolar breath sounds are the result of air moving in and out of the fine bronchi and alveoli. During inspiration the air flow enters the alveoli through the bronchi and impacts the alveolar wall, causing the alveoli to change from relaxed to tense, and during exhalation the alveoli change from tense to relaxed, this change in alveolar elasticity and the vibration of the air flow are the main factors in the formation of alveolar breath sounds. The sigh-like or soft blowing wind-like “fu-fu” sound can be heard in most of the lung fields. The tone is relatively low. During inspiration, the sound is stronger, higher in pitch and longer in duration; during exhalation, the sound is weaker, lower in pitch and shorter in duration. The lower part of the breast and the lower part of the scapula are the strongest, followed by the lower part of the axilla, and the lung tip and the area near the lower edge of the lung are weaker. The strength of alveolar breath sounds in normal subjects is related to gender, age, elasticity of lung tissue, thickness of the chest wall, and depth of breathing. Men are stronger than women, children are stronger than older people, and short and fat people are weaker than long and thin people.