A physical examination procedure which uses the sound from a percussing finger to evaluate the underlying tissues and structures of the thoracic cavity. It seeks to evaluate the degree of resonance of the chest.
With the index or middle finger of one hand strike the middle finger of the other hand just above the nail. Press your finger firmly on the patient’s chest in the inter-costal spaces. It is advisable not to let the other fingers touch the patient as this will cause dampening of the vibrations. Percuss 3-5 places on the anterior thoracic wall. Percuss first over the apices of the lungs above the clavicles. The percussion over the clavicles directly (not striking your own finger) and then progress inferiorly. Percuss at intervals of 2-3 intercostal spaces. Percuss between the ribs (intercostal space) and as you move inferiorly deviate slightly laterally as you strike the lowest positions over the 7th and 8th intercostal spaces. Compare the equivalent intercostal space from left to right sides. Repeat the process laterally in the mid axillary line. Get the patient to abduct their arms over the heads to expose the area. Repeat the percussion on the posterior wall. Get the patient to cross their arms in order to retract the scapulae. Start from the top of the thorax and continue comparing side-to-side until you reach the 8th intercostal space. When you reach the base of the resting diaphragm continue onto the assessment of diaphragmatic expansion. (see Evaluation of the expansion of the diaphragm).
A normal lung should produce a resonant sound. Dullness can signify consolidation of lung tissue such as lung fibrosis and pneumonia also with lung collapse and the accumulation of pleural fluid. Localised dullness might signify a lung tumour provided is its sufficiently large. Hyperresonance (tympani) can be heard with pneumothorax, COPD and large air-filled bulla.
Taking into account physiological changes in sounds due to changes in the underlying viscera. Remember the position of the mediastinum, the cardiac notch and heart, the spleen, the liver and stomach areas. Take into consideration the effects of sound transmission with barrel chest deformity. Make sure your percussing finger behaves like a hammer with a spring in it which bounces back after percussing. A jabbing kind of percussion will dampen the vibration as the finger will not bounce back immediately. Place firm pressure in those with large muscle development and the obese.
(Full details and demonstration of the procedure is provided with the DVD/videos and associated study material)