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From Cylinder to Stethoscope: Do You Know How It Evolved?

Laennec StethoscopeIn our technological age, it's not surprising that electronic stethoscopes are available that amplify sounds. There are even stethoscopes with Bluetooth capability that will transmit heart sounds to computer software programs designed to analyze the cause of any murmurs. While Dr. Rene Laennec invented one of the most widely used physician tools, I believe he would find the modern stethoscopes virtually unrecognizable from the instrument he originally dubbed "Le Cylindre." Laennec was a skilled woodworker, and he carved the first official stethoscope out of wood in 1816. The 12-inch long wooden cylinder had a hole on one end to place against the ear, and a funnel-shaped cone on the other for placing against the patient's chest. When Laennec published a paper on what was called 'mediate auscultation', he discussed the design of his invention and described the experiments he conducted during the evolution from rolled up papers to a hollow wooden cylinder. His stethoscope could be purchased with every copy of his treatise for 2 francs. Both sad and ironic, Laennec's nephew used the stethoscope a decade later to diagnose his uncle with the Tuberculosis that would claim his life in 1826. Laennec was the first to describe the auscultatory signs we still use in medicine today, such as 'bruit,' 'rales,' 'bronchophony,' and 'egophony.' Following his death, the stethoscope continued to evolve in various forms until it became the recognizable instrument medical professionals use today. Some of the inventions are downright horrifying to me, such as a long thin wooden attachment designed to listen to a fetus in-utero via vaginal insertion. I can only imagine that was just unpleasant for both doctor and patient . . . not to mention that the thought of splinters in all the wrong places makes me shudder. Adjustments to stethoscope design continued over the decades, but it wasn't until the early 1850s that physicians decided to try listening with both ears. Monaural stethoscopes are still used today in countries such as those of the Former Soviet Union, and by midwives in the United Kingdom and Europe. In the United States, though, the binaural stethoscope has taken precedence. Dr. George Cammann is credited with producing the first usable stethoscope intended for listening with both ears. Dr. Cammann was working as a physician at the Northern Dispensary in New York City and designed his stethoscope with ivory earpieces connected to metal tubes covered by wound silk. The tubes converged into a hollow ball designed to amplify the sound, which was attached to a cone-shaped chest piece. Modern StethoscopeHowever, our most modern and recognizable design stems from Dr. David Littmann, a distinquished cardiologist. In 1961, Dr. Littmann described his "ideal" stethoscope in the Journal of the American Medical Association, and its simple design is still the basis for most stethoscopes used in the medical industry today. Next time you reach for the instrument you use so often, take a moment to remember the century of innovation that has created it.