Hamman signA substernal crepitance, which is typically synchronous with the heartbeat, caused by percolation of air into the mediastinum.
mediastinal crunchMedtalk A substernal crepitance, often synchronous with the heartbeat, caused by percolation of air into the mediastinum–emphysema–eg, due to tracheal perforation or due to expansion of gas in rapid ascent in scuba divers. See Mediastinal emphysema.
A rasping sound, similar to the noise made when leather rubs against leather, that is heard on listening to the heart of a patient with air in the mediastinum. The sound usually is detected during cardiac systole but also may vary in intensity with breathing.