1781-1826: Laennec: The inventor of the stethoscope

Rene Laennec (1781-1826)

Before the 19th century the only way for a physician to hear heart and lung sounds was to place his ear upon his patent's chest.  This was a method first described by Hippocrates, although it wasn't standard practice.  Of course some patent's were gross and filthy in those days, considering the shower was not common place nor easy for some people.

Likewise, for a gentleman doing this to a lady the experience might be a bit uncomfortable for both the patient and the doctor.  Obesity also posed a problem because fat tissue muffles sound.  When he was 38-years-old on a hot and humid day in 1816 Laenec was posed with all of these problems.

According to Kendall F. Haven in his book "One hundred greatest inventions of all time," Laennec was a "well established doctor and diagnostician of chest and abdominal disorders when he was asked by a fellow physician to assess an obese young woman with breathing difficulties." (1)

Not that it matters, but for the record the patient's name was Marie-Melanie Basset, and she was only 40.

Laennec listens to man with tuberculosis*

Laenec's normal technique was to have the woman partially disrobe so he could place his ear against a hanker chief over her chest.  He'd listen to lung sounds over five spots:  the underside of each arm, each side of upper back, and upper breast bone.  Yet he heard nothing, so he tried percussion.

Percussion is another handy technique to help a doctor diagnose lung disorders.  This was a tecnhique not common worldwide, although in Paris it was.  In fact, percussion was a technique made famous by Laennec's teacher, Jean Nicolas Corvisant.  The doctor would tap on the chest and the sound created would be indicative of different conditions.  Doctors still use the technique to this day. 

For example, asthma causes air to be trapped in the lungs and causes a hollow sound.  Sound travels better through fluid -- like pneumonia -- and amplifies sound.  Once again, however, fat tissue drowns out sound.  While Leannec suspected the lady had heart failure, he was unable to diagnose her by heart and lung sounds.

Thinking off the cuff, however, he "grabbed 24 sheets of paper, rolled them tightly into a bundle, and secured them in shape with paste glue," wrote Haven.  "He applied one end of this paste roll against the young woman's chest, and the other to his ear."

Leanecc was "delighted" to learn he could hear the woman's heart and lung sounds better this way than with the unaided ear against her chest.  He was so excited at how simple a device could make this job so much easier that he set out to do a series of experiments to find metals and tubes that would aid his ear in hearing heart and lung sounds. 

After some tinkering he came up with the perfect device, and you can read more about it and check out some pictures by clicking here at www.hhmi.org.  His device was 12 inches long and about 1.5 cm in diameter with a 3/8 inch bore hold throughout its length, according Antiquemed.com. (2)

He actually wanted to name the device le cylindre claiming it was frivolous to name such a device.  Since he didn't like names given to his device by his colleagues, he later called it a stethoscope.  Dictionary.com defines stethe as Greek for chest and scope is Latin for aim.

Laennec's Stethoscope (1820)**

His model was pretty much a wooden tube that you put in one ear.  In the ensuing years the model was adjusted by others, and eventually a stethoscope with two ear pieces (binaural) was invented.  In 1850 George Camman fine tuned the stethoscope so it was similar to the models we use today.

Later Laennec recollected how a  little kid's game where little kids would listen to sounds through long, hollow sticks. While one end of the stick was held up to the ear, the other was scratched with a pin. The sound would be amplified. He wrote:

"The other method just mentioned [direct auscultation] being rendered inadmissible by the age and sex of the patient, I happened to recollect a simple and well-known fact in acoustics, . . . the great distinctness with which we hear the scratch of a pin at one end of a piece of wood on applying our ear to the other. Immediately, on this suggestion, I rolled a quire of paper into a kind of cylinder and applied one end of it to the region of the heart and the other to my ear, and was not a little surprised and pleased to find that I could thereby perceive the action of the heart in a manner much more clear and distinct than I had ever been able to do by the immediate application of my ear.

He was also skilled with the flute, and this may have helped him come up with his idea as well. By taking a hollowed out tube he was able to create his first sthethescope.

He discovered that his invention was better for hearing sounds inside the human body than the ear alone.  He found it very useful, and would incorporate his new tool as a means of assessing all of his patients.  He likewise used it in his efforts to study many diseases, such as tuberculosis.

Painting of Laennec using his stethoscope***

Yet when he told his peers of his new invention he was ridiculed, wrote Suzanne Barchers, in her book "I've Discovered Sound," (Brainworks, 2009).  "What a ridiculous idea," his colleagues would say.  "We doctors are called upon for our brilliant medical minds.  To say we should carry some frivolous tool around with us is absolutely ridiculous and below us." (3)

One doctor wrote, ""He that hath ears to hear, let him use his ears and not a stethoscope."

Once again the paradigm slows down progress.  So many times during the annals of time people reject change, and this resistance to change was never more paramount than in the medical profession.  For thousands of years physicians rejected any scientific idea that opposed Galen's superstitions, and now they reject a tool that would allow them to do their jobs better.

In fact, Laennec was ridiculed so much that he would end up retiring early and moved to the country side.  Yet Laennec would end up with the last laugh, as by the time he passed away  in August of 1836 the stethescope became a standard tool to assess and diagnose. 

Brainworks explains that Leanec's invention was used to help diagnose many patients with tuberculosis. And when he was 46 "he got very sick.  His own invention confirmed that he had tuberculosis."

To view more pictures of the Laennec stethescope click here.

References:

1. Haven, Kendall F, "One hundred greatest inventions of all time," 2006, page 96-98
2. "Now I hear:  The history of the stethoscope,"  http://antiquemed.com/, 1998-2011
3.  Barchers,Suzanne, "I've Discovered Sound," Brainworks, 2009, page 9

Pictures:

• * Picture from  http://www.hhmi.org/biointeractive/museum/exhibit98/content/b6_17info.html
• **Copy write Science Museum/ Science and Society Picture Library
• ***The picture was taken from a painting by Robert A. Thom, copyrighhted in 1960