Laënnec Invents the Stethoscope Summary

  • Last updated on November 10, 2022

Laënnec’s invention of the stethoscope enabled physicians to study the sounds of the living heart and lungs in detail. His meticulous and revolutionary two-volume description of his findings, published in 1819, marked the beginning of the modern study of chest diseases, which could be more accurately diagnosed, more clearly understood, and more effectively treated.

Summary of Event

During the 1750’s, Leopold Auenbrugger discovered that healthy and diseased Diseases;of the chest[Chest] chests make different sounds when they are struck. Healthy chests, which are drier and full of air, sound like cloth-covered drums. Diseased chests contain various thick fluids and sound differently muffled, depending on the particular disease. These differences can be heard, quantified, and analyzed to reach a diagnosis, but they cannot be heard easily by an unaided human ear. Auenbrugger devised techniques of striking a patient’s chest gently but firmly with his fingers. He then correlated these sounds from different parts of the chest with specific pathological implications. He named his method “percussion” and published his findings in Vienna in 1761 as Inventum novum ex percussione thoracis humani (On Percussion of the Chest, 1936). Stethoscope Medicine;stethoscope Laënnec, René-Théophile-Hyacinthe Diseases;of the chest[Chest] [kw]Laënnec Invents the Stethoscope (1816) [kw]Invents the Stethoscope, Laënnec (1816) [kw]Stethoscope, Laënnec Invents the (1816) Stethoscope Medicine;stethoscope Diseases;of the chest[Chest] [g]France;1816: Laënnec Invents the Stethoscope[0840] [c]Inventions;1816: Laënnec Invents the Stethoscope[0840] [c]Health and medicine;1816: Laënnec Invents the Stethoscope[0840] [c]Science and technology;1816: Laënnec Invents the Stethoscope[0840] Auenbrugger, Leopold Corvisart des Marets, Jean Nicolas Forbes, John Piorry, Pierre Adolphe

Physicians generally ignored percussion until Baron Jean Nicolas Corvisart des Marets, Napoleon I’s doctor, translated Auenbrugger’s work in 1808 as Nouvelle méthode pour reconnaitre les maladies internes de la poitrine par la percussion de cette cavité. With the blessing of a medical mind as prominent as that of Corvisart’s, percussion became immediately and almost universally accepted as a valuable diagnostic tool.

René-Théophile-Hyacinthe Laënnec was one of Corvisart’s students at the Hôpital de la Charité in Paris. Both men practiced the ancient technique of “auscultation,” which then meant listening to chest sounds by putting the ear directly on a patient’s body. Auscultation had many problems. It did not work with obese patients, exposed physicians to lice and contagious skin conditions, and could offend female patients. Worst of all, the sounds the doctor heard were faint and unclear. Percussion helped, but not much. As diagnosticians, both Corvisart and Laënnec wanted to amplify and clarify the sounds emitted by living chests.

In 1816, Laënnec examined an overweight woman with possible heart disease, but his examination was hampered because he could not get his ear close enough to her heart to hear it clearly. Remembering the principle that sound travels better through solids than it does through air, he spontaneously rolled up a few sheets of paper tightly into a tube and put one end on her chest and the other to his ear. The sounds he heard amazed him. He heard the heart more clearly and loudly and with less background noise than he had ever heard it before.

Laënnec and Corvisart Corvisart des Marets, Jean Nicolas instantly knew that Laënnec had stumbled upon a historic medical advance. Believing that they could now “see” inside a person’s chest with this new instrument. Laënnec named the instrument the “stethoscope,” combining two Greek words stêthos (chest) and skopos (one who watches). Auscultation thereafter became either “mediate,” using the stethoscope, or “immediate,” using the ear alone.

Soon after making his original paper stethoscope, Laënnec began crafting the instruments from wood. The stethoscopes he made were cylindrical, were about the size of a flashlight, and were called “monaural” because they could be used by one ear only. Laënnec realized that “binaural,” or two-eared, stethoscopes would be better but did not know how to create them.

Laënnec and some of his teachers, colleagues, and students were among the first scientists to understand the value of postmortem examination for studying disease. They shifted the focus of pathological research from the living to the dead, measuring their observations of cadavers against what they knew of healthy anatomy. Laënnec carefully described the chest sounds he heard in dying patients, then verified his hypotheses through autopsy and dissection, and thereby correlated specific sounds with specific diseases or conditions. His research with cadavers helped him diagnose diseases in living patients. His investigations contributed mostly to the knowledge of lung diseases, especially tuberculosis, Tuberculosis which, ironically, is what killed him at the age of only forty-five.

After three years of this research, Laënnec categorized and published his results in 1819 in the monumental two-volume work De l’auscultation médiate: Ou, Traité du diagnostic des maladies des poumons et du coeur. Sir John Forbes Forbes, John translated the work in 1821 as A Treatise on the Diseases of the Chest. Laënnec’s even more detailed second edition of his masterpiece appeared in 1826 and became a medical classic throughout the English-speaking world soon after Forbes’s 1827 translation.

Significance

In the few decades following Laënnec’s invention and his discoveries, many physicians across Europe and America augmented his work, further classifying chest sounds and increasing the diagnostic power of the monaural stethoscope. One of the earliest books in this genre was Victor Collin’s Des diverses méthodes d’exploration de la poitrine et de leur application au diagnostic de ses maladies (1824), which W. N. Ryland translated in 1829 as Manual for the Use of the Stethoscope: A Short Treatise on the Different Methods of Investigating the Diseases of the Chest. Pierre Adolphe Piorry Piorry, Pierre Adolphe reported on combined techniques of percussion and mediate auscultation in De la percussion médiate (1828).

Other major researchers with the monaural stethoscope were Jean-Baptiste Bouillaud, who gave a classic description of endocarditis in 1835; William Stokes Stokes, William and Henry Ingersoll Bowditch Bowditch, Henry Ingersoll , who wrote introductory texts on the use of this instrument; and William Wood Gerhard Gerhard, William Wood , whose description of bronchitis in Lectures on the Diagnosis, Pathology, and Treatment of the Diseases of the Chest (1842) remains unsurpassed in accuracy and detail. The greatest of these first-generation investigators of chest diseases was Josef Skoda Skoda, Josef , whose Abhandlung über Perkussion und Auskultation (1839) provided such intricate classifications and fine interpretations of chest sounds that the work remains a text for physicians.

Despite the obvious diagnostic advantages of the stethoscope, many physicians from the 1820’s to the 1850’s were reluctant to use it because its shape prevented them from simultaneously looking at and listening to the patient. Several inventors made clumsy attempts to overcome this inconvenience, but their primitive binaural stethoscopes did not transmit sound as accurately, loudly, or distinctly as the wooden monaural stethoscopes that were then common. Meanwhile, other inventors were having more success with improving the monaural stethoscope, selecting solid tubes to isolate heart sounds, using hollow tubes to isolate lung sounds, and experimenting with different kinds of wood, as well as ivory Ivory and brass.

The first successful binaural stethoscopes emerged during the 1850’s through the separate efforts of Arthur Leared Leared, Arthur , George P. Cammann Cammann, George P. , and others. A century of steady technological advances after the mid-1850s led to the development of the modern binaural stethoscope, which has a chest piece with a hollow bell on one side for isolating low-frequency sounds and a flat diaphragm on its other side for isolating high-frequency sounds. The bell/diaphragm assembly and the two earpieces are connected by about 35 centimeters (14 inches) of flexible tubing.

American physician Austin Flint Flint, Austin made so much progress with the binaural stethoscope that he was called “the American Laënnec.” Among his groundbreaking works are Physical Exploration and Diagnosis of Diseases Affecting the Respiratory Organs (1856), A Practical Treatise on the Diagnosis, Pathology, and Treatment of the Diseases of the Heart (1859), and A Manual of Auscultation and Percussion, Embracing the Physical Diagnosis of Diseases of the Lungs and Heart, and of Thoracic Aneurism (1876).

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Duffin, Jacalyn Mary. To See with a Better Eye: A Life of Laënnec. Princeton, N.J.: Princeton University Press, 1998. The standard biography on Laënnec.
  • citation-type="booksimple"

    xlink:type="simple">Kervran, Roger. Laënnec: His Life and Times. New York: Pergamon, 1960. Another good biography.
  • citation-type="booksimple"

    xlink:type="simple">Reiser, Stanley Joel. Medicine and the Reign of Technology. New York: Cambridge University Press, 1978. The second chapter of this work, “The Stethoscope and the Detection of Pathology by Sound,” places Laënnec’s invention within the context of diagnostic improvements that began in the eighteenth century.
  • citation-type="booksimple"

    xlink:type="simple">Rogers, Spencer Lee. The Monaural Stethoscope. San Diego, Calif.: Museum of Man, 1972. Appraises the fundamental technology of early stethoscopes.
  • citation-type="booksimple"

    xlink:type="simple">Sterne, Jonathan. “Mediate Auscultation, the Stethoscope, and the ’Autopsy of the Living’: Medicine’s Acoustic Culture.” Journal of the Medical Humanities 22, no. 2 (June, 2001): 115-136. Sterne examines the central place of the stethoscope in nineteenth century medical thought.

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