One autumn day in 1816, the French doctor René Laënnec found himself in a truly compromising situation. An obese young woman arrived at his office with palpitations, a symptom of possible heart disease. Her usual procedure would have been to auscultate her, if it were not for the fact that the accumulation of fat under her skin would not allow her sounds to be heard. But at the time, it was also considered indecorous to put your ear to the chest of a female patient, and even more so if she was young.
They say that the doctor, who did not know how to get out of trouble, remembered a day when he saw some children playing with the branch of a tree. While one scraped one end, the other listened to the amplified sound with his ear resting on the opposite end. This well-known acoustic phenomenon inspired an ingenious solution.
“I took a notebook of paper and made a tightly rolled roll, of which I applied one end to the precordial region, placing my ear on the other end, being both surprised and satisfied to hear the heartbeat in a much clearer and more distinctive way.” than I would ever have done by the immediate application of hearing,” Laënnec later wrote.
This rudimentary invention was the origin of the stethoscope (from the Greek stéthos, chest, and skopeîn, to observe), also called stethoscope (from the Greek prefixes phono, sound, and endo, within), used for auscultation of the internal sounds of the body. Very few instruments with such a simple design have contributed as much to medical diagnosis as this one. That’s why, two centuries later, doctors around the world still wear it around their necks.
René Théophile Hyacinthe Laënnec was born in Quimper, a town in Brittany, France, in 1781. When he was six years old, his mother died of tuberculosis in the middle of childbirth, which also took the life of the baby. Although at first he and his brother were left in the care of his father, after the outbreak of the French Revolution in 1789 they went to live with his uncle Guillaume François Laënnec in the city of Nantes.
At only 14 years old, Laënnec entered the Hôtel-Dieu medical school, where his uncle served as chief physician, and there he treated the crippled, wounded and sick as a result of the wars that pitted revolutionary France against several European powers. When he completed his preparatory training, he made the decision to study medicine in Paris.
His notable academic performance caught the attention of who would later become Napoleon Bonaparte’s personal physician, Jean Nicolas Corvisart (1755-1821), who placed him under his tutelage. The young student received training in anatomy, physiology, chemistry, botany, pharmacy, legal medicine and the history of medicine, and soon made a name for himself as one of the greatest representatives of the anatomoclinical method.
This new hospital trend developed, at the beginning of the 19th century, semiology – part of medicine that studies the symptoms of diseases – through new techniques and exploration instruments such as auscultation, palpation or percussion, which allowed better diagnoses to be established.
Laënnec himself examined and auscultated a large number of tuberculosis patients, and therefore described a wide variety of respiratory sounds. This disease would also end up taking his brother at that time.
At the age of 35, Laënnec assumed the leadership of the Necker Hospital in Paris, the same one where he treated the young woman with palpitations. There he dedicated his efforts, mainly, to percussion as a method of auscultation. Immediate auscultation was known and practiced by doctors since ancient times.
However, a significant advance occurred in the 18th century when the Austrian doctor Leopold Auenbrugger introduced digital percussion. This physical examination technique consists of gently tapping the patient’s body surface with the fingers of the hands. Auenbrugger had noticed that, in healthy patients, a sound similar to that of a drum was obtained; On the other hand, the sound varied in patients with respiratory diseases.
Although he put his findings into a small book in 1761, they were received with indifference. Recognition would not come to him until almost fifty years later, when Corvisart translated the work into French, adding his own observations, and incorporated the method into his medical practice. Thanks to this, his disciple, Laënnec, came to know the clinical value of percussion.
To study lung and heart sounds in detail, that roll of paper that the French doctor placed on his patient’s chest in 1816 was soon replaced by a wooden cylinder 30 centimeters long and 4 centimeters in diameter and hollowed in the shape of a funnel in one of its extremes.
Three years later, in 1819, Laënnec published a treatise on the diagnosis of diseases of the lungs and heart using the new means of examination. In the book he described the sounds he heard with the device and detailed some diseases unknown until then, such as emphysema or pneumothorax.
The work began to gain popularity, and specialists soon understood the advantages that the stethoscope represented over the old technique of listening directly, which gave rise to all kinds of interpretation errors. Medical students from all over Europe came to Necker Hospital to learn how the new diagnostic instrument worked.
Laënnec died of tuberculosis in 1826, the year in which the second edition of his work appeared. In it, he says that he had cut himself at least seven times while working with tuberculosis corpses, and highlights an episode that occurred in 1802 in which, while examining some diseased vertebrae, the saw eroded the index finger of his left hand. This is how the bacillus must have been inoculated. It is paradoxical that his own illness was not diagnosed until he was already in an advanced state.
After Laënnec’s death, the stethoscope was progressively perfected. In 1828, for example, the Frenchman Pierre Adolphe Piorry invented the pleximeter, a simple instrument made of wood and ivory shaped like a trumpet. The first references to flexible stethoscopes date back to 1832.
But the real revolution came in 1851, when the device went from being monaural (a single tube) to binaural (which conducts the sound to two headphones) by the Irishman Arthur Leared, and was perfected just a year later by the New Yorker George Cammann. The latter’s design had a pair of flexible tubes that were covered at the end with ivory earpieces. The instrument could be mass produced, and George Cammann generously waived the patent.
1895 marks another milestone in the history of the endoscope. It was the year in which Adolphe Pinard, concerned about deaths during childbirth, devised a device with the trumpet-shaped end a little more open to be able to detect the heartbeats of babies through the abdomen of pregnant women.
In the early 1960s, a distinguished cardiologist, David Littmann, a professor at Harvard Medical School, patented a new stethoscope with much improved acoustics. With this, a simple listening device became a powerful diagnostic tool.
Although nothing to do with modern electronic stethoscopes, which record, visualize and share the sound of the auscultation through an app, ultimately making it easier to obtain more accurate diagnoses at a low cost. The future of auscultation in medicine is already here.
This text is part of an article published in number 614 of the magazine Historia y Vida. Do you have something to contribute? Write to us at redaccionhyv@historiayvida.com.