Abnormal percussion sounds in the lungs are knowledge points involved in the clinical medical professional skills examination of the third station. Yincheng Medical Exam has collected relevant materials to facilitate everyone’s quick preparation.

In all normal lungs, except for the heart and liver, the sound on percussion is clear. If dull or flat, drum, or hyperresonant sounds are heard, it indicates an abnormal percussion sound, reminding of the pathologic changes in the lung and pleura, and the sternum. The level of abnormal percussion sound depends on the size, location, and characteristics of the disease. Superficial diseases (more than 5 cm from the surface of the sternum), small-scale diseases (less than 3 cm), or small amounts of pleural effusion (less than 250 ml) often cannot be detected by percussion sound changes; scattered loose diseases can cause slight dullness; large-scale diseases with high relative density and close to the surface of the sternum can produce significant dullness; a large amount of pleural effusion can produce a flat sound.

1. Physiological dull or flat sound

(1) A decrease or disappearance of the air supply in lung tissue such as pneumonia, tuberculosis, lung abscess, atelectasis, high-width ratio edema, and generalized fibrosis.

(2) The formation of airtight tissue within the lung such as lung cancer, cysticercosis, etc.

(3) Changes in the pleura such as pleural effusion, pleural thickening, or pathologic changes in the sternum (edema, tumors, etc.).

2. Physiological drum sound

(1) Large fissures within the lung, such as those caused by tuberculosis, lung abscess, or the cavities formed after the rupture of lung tumors or cysts, can produce a drum sound. However, the fissures generally need to be over 3-4 cm and close to the sternum.

(2) Pneumothorax

3. Hyperresonance

Excessive reaction with a tone higher and stronger than the clear sound, lower than the drum sound, being a叩诊音 between the clear sound and drum sound. Common in emphysema patients.