Louis Virgil Hamman (1877 - 1946)

Louis Virgil Hamman (1877-1946) was an American physician.

Born in Baltimore (1877) initially pursuing a career as a priest before later matriculating to John Hopkins Medical School. He graduated in 1901 with initial interests in pulmonary tuberculosis. His other hobbies included a passion for literature and Bridge.

The depiction of mediastinal ephysema (1945) was the acculumation of his research investigating an unusual clinical finding when he examined a chest.

Credited for Hamman-Rich syndrome, Hamman Syndrome and Hamman sign.

  • Born on December 21, 1877
  • 1895 – BA, Rock Hill College in Ellicott City, Maryland
  • 1901 – MD, Johns Hopkins School of Medicine
  • Died on April 28, 1946

Medical Eponyms
Hamman-Rich syndrome (1935)

This eponymous name previously referred to as ‘acute diffuse idiopathic interstitial pulmonary fibrosis of unknown aetiology’ and now known as Acute Interstitial Pneumonia (AIP).

Hamman and American pathologist Arnold Rice Rich (1893-1968) described the rapid proliferation of connective tissue and fibrosis following a chest infection. Often misrepresented as Acute Respiratory Distress Syndrome (ARDS).

From the Pathological Anatomy and the symptoms of these four patients we may reconstruct the course of an uncommon and remarkable disease. Pulmonary inflammation develops insidiously with little local or constitutional disturbance. Very shortly after the onset of pulmonary infection there occurs a marked proliferation of connective tissue which greatly thickens the alveolar walls and obliterates many of the air sacs and soon dyspnea comes on and grows increasingly severe as a result of the fibrosis which disturbs the relation of the alveolar capillaries to the air spaces and encroaches upon the alveoli themselves. At an early stage of the disease the exudate may be so extensive throughout all lobes of both lungs that acute suffocation occurs. At a later stage, as happened in two of our cases, the patient may die of a slowly progressing suffocation.

Hamman and Rich 1933

By Stigler’s law of eponomy, Hamman and Rich were not the first to describe this process. The first documented pathological review of the disease process was by Sir Dominic John Corrigan (1802-1880) in a process he termed ‘cirrhosis of the lung‘. Later in 1897 by Rindfleisch as Cirrhosis Cystica Pulmonum

Hamman’s sign (1939)

Describing a ‘crunching sound’ heard in relation to mediastinal emphysema. Hamman first described the sound in a series of cases presented in the the second Henry Sewall Lecture at Johns Hopkins Medical School in 1939.

Case 1: Dr. Esler heard the sound and interpreted it to be a pericardial friction. This seemed to confirm the diagnosis of coronary occlusion…I examined the heart and the lungs with the greatest care and could detect nothing that was to the least degree abnormal. When I expressed chagrin at my lack of skill, the patient laughingly said that he could easily bring on the sound which had excited so much interest. He turned on his left side and after shifting about for a few moments said, “There it is, I hear it now.” I put my stethoscope over the apex of the heart and with each impulse there occurred the most extraordinary crunching, bubbling sound. It is difficult to describe. Crunching is the best adjective I can think of though it is far from apt, especially since crunching has been widely used to describe pleural friction, to which it bore no resemblance. It certainly conveyed the impression of air being churned or squeezed about in the tissues.

Hamman 1939

Hamman further defined the auscultation findings in spontaneous mediastinal emphysema in 1945.

I have no doubt that at times the distinctive auscultatory signs may be absent, although in their absence it would be difficult to decide with certainty that mediastinal emphysema is present.

These peculiar sounds consist of crackles, bubbles or churning sounds heard with each contraction of the heart. They may be heard only during systole or during systole and diastole, but always with systolic accentuation. They may be so soft that to be heard they must be listened for attentively; they may be so loud that they can be heard at a distance. Very often the patient himself is aware of the sounds and calls attention to them. They may be loudest over the lower portion of the sternum and to the left of the sternum or near the apex of the heart. They may be heard when the patient sits up and disappear when he lies down or be plainly heard when he lies on the left side and absent in other positions.

Hamman, 1945

The Incidence of Hamman sign is estimated around 12.2% in pneumomediastinum.

Hamman syndrome (1939)

Initially described as spontaneous mediastinal emphysema – defined as the presence of mediastinal free air in the absence of an obvious precipitating cause.

Often incorrectly referred to as Macklin syndrome/effect (1937) which comparatively described the pathophysiology whereby increased alveolar pressure caused alveolar rupture. However this is a involved in primary and secondary pneumomediastinum.

Hamman syndrome is estimated to have an incidence of 1 in 30,000.

Major Publications



Eponymous terms


Hamman’s Syndrome

Hamman’s sign

Dr William McGalliard LITFL Author

Graduated Medicine in 2020 from Queens University Belfast. Interested in Internal Medicine.

BA MA (Oxon) MBChB (Edin) FACEM FFSEM. Emergency physician, Sir Charles Gairdner Hospital.  Passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |

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