In the beginning of a string of podcasts about sound in medicine, Bedside Rounds goes back to the beginning, with the invention of the stethoscope by Rene Laennec. How was the stethoscope invented? What are doctors listening for when they listen to their lungs? Who was Rene Laennec? Well, learn all the answers to these questions in Episode 9 of Bedside Rounds, Laennec’s Cylinder!
Hi, my name is Adam Rodman, and you’re listening to Bedside Rounds, a tiny podcast about fascinating stories in clinical medicine. I’m starting a series about sound in medicine, and this week’s episode is called Laennec’s Cylinder, appropriately starting at, well, the beginning, with the invention of the stethoscope.
Initial caveat — doctors have been listening to their patients’ bodies for a very long time. What we now call “immediate auscultation” — that is, directly placing your ear on a patient’s chest — dates back to the beginning of recorded history. Egyptian papyruses refer to audible signs of disease. Hippocrates, styled as the father of medicine, described placing his ear to the chest to hear fluid in the lungs, and even invented a method — which sounds pretty unpleasant to me — of grabbing patients by their shoulders and violently shaking them to evoke sounds from the chest. By the 1600s, physicians had described the two sounds of the heart — William Harvey described them as “two clacks of a water-bellows to raise water,” and it became standard of practice, especially in France, to place your ear directly on a patient’s chest to listen to the heart. Surprisingly enough, immediate auscultation lasted well into the 20th century. In fact, there’s an op-ed in Circulation by Dr. Vittorio Puddu in 1975 advocating it for patients who have an extra heartbeat, or gallop.
Not much changed until the 1700s, and like most great things in life, it changed because of wine. Leopold Auenbrugger, a prominent Viennese doctor, had grown up the son of an innkeeper and had watched his father tap a barrel of wine to see if it was full or empty. He realized that the chest was not too different from a barrel of wine; normal lungs, full of air, are tympanic, and sound like this — [tympanic lungs]. But get those lungs full of wine, or rather, secretions, fluids, blood, or whatever badness have you, and they are dull, sounding like this — [dull lungs].
And it’s with this backstory that brings us to 1816 and Rene Theophile Hyacinthe Laennec — which is an amazingly awesome name, and I’m just going to go ahead and apologize to any French speakers in the audience, since apparently three semesters of French in college did nothing for me. Dr. Laennec was a young, talented physician, only 35 years old, working in the tuberculosis wards of Necker Hospital in Paris. On a cool September he was walking through the courtyard of the Louvre in Paris, then a palace and not a museum with a giant glass pyramid, Laennec saw two children playing a game with a piece of wood. One child would scratch one end of the stick with a pin, transmitting the sound through the wood. [scratching on wood]. Shortly thereafter, he was called to treat a young woman with “general symptoms of a diseased heart”. Laennec, a modern, scientific physician, felt her heart with his hands, and percussed like Auenbrugger to see if he could find the cause of her disease. But alas; he did not have enough information. He would have to listen to her chest. Dr. Laennec was a gentleman, and a modest one at that. And he was not about to place his head against the breast of this plump young woman.
But he remembered those children playing at the Louvre, and grabbed a 24-page pamphlet, and rolling it into a tube, placed it on her chest and placed his ear to the other side. And this is what he heard:
[heart sounds]
Thus was born the stethoscope, taken from Greek for “I see” and “the chest”, though I prefer the translation “exploring the chest”. Laennec was a talented woodworker, and he immediately went to his home and started experimenting with different materials. After three years he finally mastered his creation, which he called “le cylindre” — a hollow wooden tube with a removable plug that made it portable.
If Laennec had stopped there, he would already have been a luminary in the world of medicine. But the young doctor took his creation to the tuberculosis wards at Necker hospital, listening to the chests of patient’s stricken with tuberculosis. He tirelessly recorded and analyzed breath sounds of his patients, and lucky him, tuberculosis had a pretty lousy mortality rate in the days before antibiotics, he was able to do autopsies on most of his patients and correlate the breath sounds he heard with the disease in their chest. He published his findings in “De l’auscultation médiate ou Traité du Diagnostic des Maladies des Poumon et du Coeur” in 1819, where he described his invention and the types of breath sounds he heard. The terminology that he defined are still used today, though not without some controversy — and I am not going to get into that controversy, but full disclosure, use modern terms and not the terms that Laennec defined.
Now let’s have some audience participation. Take in a deep breath. That’s right. Now hold it and exhale. Right now your chest wall is expanding, pulling out your lung tissue and causing the outside air to rush in as the pressure in your lungs drops. Assuming you don’t have any horrible lung disease, this is what you sound like from a stethoscope on your back:
[lung sounds]
These are normal lung sounds. Laennec noticed that he could sometimes hear extra lung sounds on top of normal lung sounds, which he called adventitious lung sounds. For example, this fine noise happens in inspiration:
[crackles]
is called “rales” r a l e s, though most modern doctors call it crackles, for obvious reasons. It kind of sounds like rice crispies. It suggests fluid sitting in the lungs, whether it’s blood, pus, or water. Classically, this is the sound that you might hear in a patient with a heart failure exacerbation, when their lungs fill with fluid. This is one that probably sounds familiar to you:
[wheezes]
That’s wheezing, or what Laennec called “rhonchi”. This suggests an obstruction of a large airway, like in asthma, COPD, or, say, aspirating a peanut.
Laennec’s stethoscope inspired physicians to develop new maneuvers to figure out what was going on in the chest, most notably egophony and whispered pectoriloquy. In egophony, the patient says the letter E while the physicians listens over the back. Fluid filters out lower frequency sounds, so if that E sounds like an A to the doctor, we can presume there’s a consolidation. Whispered pectoriloquy — don’t worry, I can really pronounce that either — takes advantage of the fact that fluid transmits sounds further — the same way that whales communicate long distance over water. The patient whispers softly something with a lot of vowels — I always use toy boat, though Scooby Doo is a popular one too — and if the doctor can hear it clearly, we guess that there’s fluid — like a pneumonia — covering that portion of lung.
Laennec’s invention changed medicine, though the form of the stethoscope changed — wood changed to rubber, a single earpiece changed to two, his rubber plug became a diaphragm. It changed medicine so much that the stethoscope hanging from the neck has become an essential symbol of a physician, maybe even more than a long white coat (which also has an interesting history, and I’m sure I’ll make a podcast about that in the future). And it’s a nice symbol too — an enlightenment piece of technology, based on physics, perfected by experimentation and meticulous observation. And it’s not like Laennec patented his stethoscope; it was freely copied for the betterment of man.
Yet despite all that, using the stethoscope is a dying art. Patients have stethoscopes placed over their lungs all the time. I would argue that the amount they actually have their lungs listened is considerably less. There’s wide agreement that modern doctors just aren’t that good at listening to lungs. For example, a 1997 systematic review of pneumonia diagnosis by Dr. Metlay found low-to-moderate levels of intra-operator agreement for a variety of lung sounds, meaning that different doctors couldn’t even agree well with what they heard.
Why is this? In short, technology. The X-ray, invented in the late 1800s by Roentgen, and used routinely by World War I, allowed physicians to peer directly into the chests of their patients, and see the white out of lobar pneumonia, the “ground glass” of an atypical infection, the fluid collections of heart failure, or the cavitary lesions of TB or lung cancer. As the use of x-rays and their later iterations of computed tomography aka CT scans spread, it became less important to be able to listen to the lungs accurately. With so much data at our fingertips, our physical exam skills began to atrophy, so much so that pretty much no doctor makes a diagnosis of pneumonia without first getting a chest x-ray.
And don’t get me wrong — I’m happy we can make diagnoses more accurately than ever. But I can’t help but feel that we’ve lost something, me listening to my patient the same way that Laennec used a tube of paper to listen to the chest of that young woman back in 1816. And maybe we will get back there. With the current expansion of tiny bedside ultrasounds, we’re starting to see a new type of “exploring the chest” with sound. It’s already being used to help see if a patient has heart failure or a collapsed lung, and the technology is constantly improving.
So there you have it — the story of the stethoscope, and the birth of sound in medicine. But our story isn’t quite at its end. What happened to our hero, Rene Laennec? Well, he had a prodigious career, describing Laennec’s cirrhosis, still used today, discussing melanoma, and discovering types of tuberculosis that flourished outside the lungs. But his story does not have a happy ending. When Laennec was in his early 40s, he became ill, lost weight, developed fevers and night sweats and developed a hacking, productive cough. He left Paris to his native Brittany to try and get fresh air, but he continued to decline. Finally, in the summer of 1826, he asked his nephew Meriadec to listen to his lungs with a stethoscope. They were sounds that Laennec had heard countless times in the wards of Necker hospital — the rales of cavitary tuberculosis. The disease he had dedicated his life to studying would now take his life; diagnosed with his life’s legacy. He died on August 13, 1826. He was only 45 years old.
Well that’s it for the podcast. Thanks for listening. This episode was all about sound, and maybe you noticed the dramatic increase in sound quality. Well, that’s because my wonderful parents bought me a microphone with a condenser as a birthday present. No more USB headphone mic for me! So thank you guys for that..
This was actually the first episode that I had envisioned for my podcast, but I didn’t know enough about audio editing to make it. I’m still not sure I know enough about audio editing to make it, but let me know how you feel — find me on Twitter @AdamRodmanMD, or on our Facebook page @Bedside Rounds. I have a lot of new listeners, so I want to thank all of you, listeners old and new. If you like Bedside Rounds, you can find all our episodes on the website at www.bedside-rounds.org. I’m also on Stitcher and iTunes — and feel free to give me a rating on iTunes! And if you like us — tell a friend! The more the merrier.
And now for my sources:
Rene Theophile Hyacinthe Laënnec (1781–1826): The Man Behind the Stethoscope by Ariel Roguin in Clinical Medicine and Research in September 2006.
The Art of Listening by Rachael Hajar in Heart Views, published in winter 2012.
René Laennec (1781-1826) and the invention of the stethoscope. by Dr Fayssoil, in the American Journal of Cardiology in September 2009.
Does This Patient Have Community-Acquired Pneumonia? Diagnosing Pneumonia by History and Physical Examination, JAMA Rational Clinical Exam, Joshua P. Metlay, MD, PhD; Wishwa N. Kapoor, MD, MPH; Michael J. Fine, MD, MSc
And finally, as always, while I am actually a doctor and I don’t just play one on the internet, this podcast is intended to be purely for entertainment and informational purposes, and should not be construed as medical advice. If you have any medical concerns, please see your primary care provider.