Coarse percussion, using 3 or 4 fingers to lightly tap on the chest, can compare the two sides, and pick up stony dullness, this is then precisely mapped by more careful percussion (figure 18).
Percussion requires considerable practice, and the ability to percuss well is obvious to an observer; it usually denotes that you have spent a reasonable amount of time on the wards. Start percussion at the apex, bearing in mind that there are 1 or 2 cm of lung above the clavicle. The clavicle is percussed directly by your finger. Percuss the rest of the lung initially anteriorly, then within the axillae. Percuss the same area on the two sides consecutively, for comparison (figure 19a–l).
The percussion may be resonant, dull or stony dull. A hyper-resonant tone may indicate an underlying pneumothorax although in practice this is difficult to detect. The axillae are best percussed by asking the patient to raise their arms above the head, and place your fingers as high up in the axilla as possible. Failure to do so may miss vital physical signs.
Your percussion of the anterior chest also defines the cardiac borders (page 223): right border (figure 20a–c), left border (figure 21a–c) and the upper border of the liver (figure 22a–c). Place your percussed finger parallel to the edge you are seeking, and percuss from resonant (hollow lung) to dull (the solid organ).
Tactile vocal fremitus may be found by placing the side of your hand over each lung during enunciation (figure 23a,b). However, it is less effective in assessing the lung’s ability to transmit sound than vocal resonance (see below).