Q; What is Hamman's sign?
Answer: Hamman's sign, also known as, Hammond's sign or Hammond's crunch - as the name implies is a crunching sound on the chest wall. It is mostly synchronous with the heartbeat. It is due to spontaneous mediastinal emphysema. It is produced due to cardiac beats against air-filled subcutaneous tissues. It is best demonstrated by the patient at the left lateral position. The distinguishing feature are the crackles that correlate with the heart beat and not the respiratory cycle.
Clinical significance: If heard on an exam in a patient with respiratory distress, it points towards localized spontaneous pneumothorax; but not a total lung collapse, on the left side. If severe, it can be visualized too.
Hamman's sign is little different though related to Hamman syndrome, which is a spontaneous pneumomediastinum and SQ emphysema, mostly happening either peri or postpartum. The condition is usually benign and self-resolving, but clinicians tend to confuse with Boerhaave syndrome.
1. Hadjis T, Palisaitis D, Dontigny L, Allard M (March 1995). "Benign pneumopericardium and tamponade". Can J Cardiol 11 (3): 232–4
2. Bonin MM. Hamman's syndrome (spontaneous pneumomediastinum) in a parturient: a case report. J Obstet Gynaecol Can. 2006;28 (2): 128-31