Hamman's sign (rarely, Hammond's sign or Hammond's crunch) is a crunching, rasping sound, synchronous with the heartbeat, heard over the precordium in spontaneous mediastinal emphysema produced by the heart beating against air-filled tissues.
It is named after Johns Hopkins clinician Louis Hamman, M.D.
This sound is heard best over the left lateral position. It has been described as a series of precordial crackles that correlate with the heart beat and not the respirations.
Also heard together with spontaneous pneumothorax; small and not a total lung collapse, on the left side. Sounds like bubbles hitting the inside of the chest. Can be felt/seen.
Causes
Hamman's crunch is caused by pneumomediastinum or pneumopericardium, and is associated with tracheobronchial injury due to trauma, medical procedures (e.g., bronchoscopy) or proximal pulmonary bleb rupture. It is commonly seen in Boerhaave syndrome.