In normal people, when inhaling, the spirals pass through the respiratory system and bronchi, causing flow and vibration, emitting sound, which is transmitted to the skin surface through the lung tissue and sternum. This is the wet rales. According to the compressive strength, pitch, characteristics, duration, and lung auscultation position of the wet rales, it is divided into four types.

Bronchial wet rales are one of the normal wet rales in lung auscultation, which is the result of the movement of gas in the bronchitis and bronchi. During respiration, the airflow passes through the bronchitis into the bronchus, impacting the bronchial wall, causing the bronchus to become anxious from relaxed. During respiration, the bronchus becomes more relaxed from anxious. The changes in bronchial elasticity and the vibration of the spirals are the key factors in the production of bronchial wet rales.

The causes include: increased air coefficient of the blood pressure body, causing prolonged and rapid inspiration, such as physical exercise, fever, or hyperactive metabolism, etc.

Insufficient oxygen in the blood stimulates the respiratory center, causing increased respiratory movement, such as anemia.

Increased blood acid value stimulates the respiratory center, causing prolonged inspiration, such as metabolic acidosis. Increased wet rales on one side of the bronchus are common in one side of the lung chest disease causing bronchial wet rales to weaken, at this time, the healthy lung can produce compensatory increased bronchial wet rales.

3) Increased respiratory sounds: due to partial obstruction, spasm, or narrowing of the lower respiratory tract, such as bronchitis, bronchial asthma, etc., causing increased friction resistance of respiration, or because of reduced elasticity of lung tissue, making the driving force of respiration weaken, such as chronic obstructive pulmonary emphysema. All these can cause increased respiratory sounds.

4) Intermittent wet rales: reversible inflammation in the lungs or bronchial stenosis, which prevents the uniform entry of air into the bronchus, can cause intermittent wet rales. Due to the brief irregular intermittent periods, it is also called cogwheet breath sound. It is more common in tuberculosis and pneumonia, etc. Be sure to note that during cold weather, pain, and anxiety, additional sounds of intermittent muscle contraction can also be heard, but they are unrelated to respiratory movement and should be distinguished.

5) Irregular wet rales: caused by slight edema or inflammation of the bronchitis mucosa, which leads to unevenness or narrowness, causing obstruction of the air spirals in and out, and producing irregular wet rales, commonly seen in the early stage of bronchitis or lung inflammation.