mediastinal crunch

Hamman sign

A substernal crepitance, which is typically synchronous with the heartbeat, caused by percolation of air into the mediastinum.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

mediastinal crunch

Medtalk 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.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

mediastinal crunch

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.
Medical Dictionary, © 2009 Farlex and Partners