History of Littmann Stethoscope
The term stethoscope is derived from two Greek words; stethos (meaning chest) and scopos (meaning examination). Apart from being used by medical practitioners to hear the heart and chest sounds, the stethoscope is also used to listen to bowel sounds and blood flow noises within the veins and arteries.
The first stethoscope was invented in 1816 by a French physician known as Rene Laennec who used a long, rolled paper tube to funnel the sound. The stethoscope was somewhat simple, but very effective. Three years later, Laennec improved his paper stethoscope into a wooden monaural stethoscope that had a large diameter base that funneled sound through a small opening. But, unlike modern scopes, this early version only transmitted sound to one ear and had ivory ear-tips.
It wasn’t until 1843, that George P. Cammann of New York developed the first binaural (sound into both ears) stethoscope. This is the model that would be used for over 100 years with very few modifications, one of which was the introduction of an ebony chestpiece with tubing made of spirals of wire that was covered in layers of silk dipped in gum elastic. Another modification to the original Cammann stethoscope was done in 1890 when the device was refined with a steel spring between the metal ear tubes.
In 1961, Dr. David Littmann, M.D., (1906-1981), a noted cardiologist, distinguished professor at Harvard Medical School, researcher, inventor, and a recognized international authority on electrocardiography, patented a revolutionary new stethoscope with greatly improved acoustics.
Considered as the most significant milestone in the development of the stethoscope, Dr. Littmann’s invention was a streamlined, lightweight stethoscope, with a single tube binaural, which was available in both stainless steel and light alloy.
The device was described by Dr. Littmann, in the November issue of the AMA journal, as the ideal stethoscope. It included a closed chestpiece with a stiff plastic diaphragm to filter-out low-pitched sounds. It also had an open chestpiece to hear low frequency as well as high frequency sounds.
Other innovative features of Dr. Littmann’s stethoscope included firm tubing with a single lumen bore, a spring with precise tension to hold the ear tubes apart with firm and short tubing and had the shortest practical overall length. The device was generally light and convenient to carry and use.
In a bid to promote his invention, Dr. Littmann founded the company Cardiosonics. This company was meant to produce two distinct stethoscopes, one for doctors and another for nurses. On April, 1st 1967, 3M, upon recognizing the acoustics and unique design of the Littmann nurse stethoscopes, decided to acquire Cardiosonics. Dr. Littmann then worked for 3M as an adviser where he helped to further innovate this essential diagnostic tool.
Throughout the years until the late 1970′s, 3M had developed a total of 40 “combination stethoscope” models. The devices were mainly in stainless steel and aluminum featherweight. They had pediatric size, gold-plated chestpieces. The tubing color was still limited to black and grey with lengths of 22 and 28 inches.
It is during this period that the ultimate 3M Littmann Cardiology Stethoscope was born. Commonly known as the “cardiologists’ dream stethoscope” because it was developed by a team of 50 world’s leading cardiologists, this product had a revolutionary two-tubes-in-one design, softer ear-tips and deeper bell for improved response to low frequency. Improvements to the product continued henceforth and in 1987, Tom Packard, a 3M engineer, invented the 3M Littmann Master Cardiology StethoscopeFeature Articles, a unique single-sided chestpiece stethoscope which features 3M’s tunable diaphragm technology.
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