Friday, April 27, 2012

Stethoscopes: Focus on Laennec

The physician is often associated with the stethoscope as one of the main tools of the profession. 

The history of the stethoscope really belongs to Frenchman and Professor of Medicine Rene Laennec (1781-1826), who invented the stethoscope in 1816. Laennec was a gifted child whose mother died of tuberculosis when he was three. Raised first by his great-uncle until age eleven, Laennec's uncle Guillaime-Francois then took over his care and often took him to his place of work as Faculty in the Medical University Nantes (1).

Laennec was trained in the art of acoustics and was a skilled flautist. In Paris medical school, he was also trained to use sound diagnostically and studied under such famous physicians as Nicolas Corvisart des Marest, who helped re-introduce percussion during the French Revolution. Laennec also studied under Baron Guillaume Dupuytren (1777-1835). Dupuytren of course, is known today for describing the surgical correction of Dupuytren's Contracture, published in the Lancet in 1831 (2) . This is the same Dupuytren French military surgeon and anatomist who received much notariety for treating Napolean Bonaparte's hemmorhoids.

In 1819, Laennec published a treatise on the following clinical terms that are still used to describe lung sounds: egophony, crepitance, rales, and rhonchi (3). He wrote this from the "Hopital Necker - Enfants Malades". In 1821, the New England Journal of Medicine published the stethoscope as a new invention.

Laennec termed his instrument the stethoscope, after stethos for chest, and skopos for examination. He used a long wooden tube as depicted above. At the time, Laennec's invention was not completely acclaimed. The clinical exam consisted of the physician putting his/her ear to the patient's chest. This was embarrassing especially if the patient was obese and had a large bust. Many physicians carried a silk kerchief that was used to place on the patient's chest for direct, "immediate auscultation". Laennec described the stethoscope as "mediate auscultation", for indirect listening. Today, the four clinical examinations still taught to medical students include inspection, palpation, auscultation, and percussion (4).

Laennec died of tuberculosis in 1826.
British physician Golding Bird (1814-1854) is attributed with casting the first flexible stethoscope in 1840.
Irish physician Arthur Learned described the biaural stethoscope meant for both ears in 1851.
This design was later perfected by George Cammann for commercial production in 1852.
"He that hath ears to hear, let him use his ears and not a stethoscope." ~ A Professor of Medicine, in 1885.
Carried a silk handkerchief for direct auscultation ~ L.A. Connor (1866-1950), Founder of the American Heart Association.
Rappaport and Sprague described a stethoscope with two sides, one for the heart and one for the lungs, in the 1940's.  Hewlett-Packard later made this one, and it can still be purchased as the Rappaport-Sprague stethoscope.
A Professor and researcher at Harvard Medical School, German cardiologist David Littmann (1906-1981) invented a newer, lighter stethoscope with better sound in the 1960's.
3M-Littmann invented both the tunable diaphragm and "cardiology tubing" that included a bifurcating tube with an internal septum that houses separate  left and right channels in the 1970's.
The DRG Puretone was invented by Richard Deslauriers as a noise-reducing stethoscope in 1999.
The fetal stethoscope is used to ascultate fetal heart tones through the abdominal wall of the pregnant woman (5). It is also known as the Pinard's stethoscope, or simply a pinard, named after the French obstetrician Adolphe Pinard (1844- 1934).

Today, super sensitive electronic stethoscopes with MP3 recording and playback capabilities are used for satellite care.
 

References:

(1) http://en.wikipedia.org/wiki/Ren%C3%A9_Laennec
(2) http://en.wikipedia.org/wiki/Dupuytren%27s_Contracture
(3) Laennec, RTH (1819) De l'Auscultation Mediate ou Traite du Diagnostic des Maladies des Poumons et du Coeur. Pris: Brosson & Chaude.
(4) http://en.wikipedia.org/wiki/Percussion_%28medicine%29 
(5) http://en.wikipedia.org/wiki/Stethoscope


For today's online buys, visit http://arandamd.com/STETHOSCOPES.html.
Disclosure: Margaret A. Ferrante is contracted with suppliers to earn commission from any stethoscope sales purchased through this website. 

This Copyright Symbol is in reference to the image above:
Public domain This work is in the public domain in the United States because it was published (or registered with the U.S. Copyright Office) before January 1, 1923. Public domain works must be out of copyright in both the United States and in the source country of the work in order to be hosted on the Commons. If the work is not a U.S. work, the file must have an additional copyright tag indicating the copyright status in the source country.

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