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BRIEF COMMUNICATION
Year : 2022 | Volume
: 8
| Issue : 3 | Page : 168-173
I look into the chest: History and evolution of stethoscope
Rony Vincent
Department of General Medicine, Amala Institute of Medical Sciences, Thrissur, Kerala, India
Correspondence Address:
Rony Vincent
Department of General Medicine, Amala Institute of Medical Sciences, Thrissur - 680 555, Kerala
India
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/jpcs.jpcs_77_22
Early physicians were taught with immediate auscultation, placing the ear directly on the patient's chest. They showed reluctance because it was questionable when the patient is obese, nonhygiene, and modesty, especially in cases of females. In 1816, when the freshly graduated physician René-Théophile-Hyacinthe Laënnec had a consultation with a young obese woman with the symptoms of underlying heart disease, he recalled an acoustic phenomenon which is known very well beforehand for him. He rolled up a sheet of paper and placed one end to her chest and another to his ear to listen. Rest is history. He presented his invention to the world and made revolutionary changes in the art of patient care, which is valuable even nowadays. After his discovery, several scientists contributed their works to make this crucial device achieve more potential. Through many years, Laennac's device became the stethoscope that we have today. Now, the stethoscope has become the symbol of the medical profession.
Keywords: Heart auscultation, history, stethoscopes
Although the invention of the original stethoscope occurred in the 19th century, practitioners have been listening to the chest since the olden days of Hippocrates. The method was called “immediate auscultation” while practitioners directly put their ears on the chest of the patient to listen to lung and heart sounds. Hippocrates practised immediate auscultation in Ancient Greece. He described succussion splash of hydropneumothorax, the frictional rub of pleuritis and other types of medical sounds.[1]
Heart sounds heard during immediate auscultation fascinated the early practitioners. Despite the fact that they must have been listened to, they were never discussed prior to the 17th century. William Harvey carried it out in 1628. Through his De Motu Cordis, he made an effort to explain the motion of both the heart and the blood.[2]
Robert Hooke, who was an expert in multiple fields, became familiar with heart sounds and predicted the utility of auscultation by following Harvey's findings and his anatomical knowledge. He wrote, “Who knows, it may be possible to discover the motions of internal parts of bodies by the sounds they make.”[3] Hooke was already familiar with a potential prototype to listen to the sounds. Ironically, before delving into the subject of interior sounds, he considered other perspectives on cardiac movements. Since there was still much that required to be addressed before listening to these sounds, his thoughts about creating a sensitive tool had no discernible impact on medicine.[4]
In 1715, James Douglas documented an aortic regurgitation murmur as a trembling noise which could be heard at some distance from the patient's bedside.[5],[6]
In 1757, William Hunter used information he learned from his medical observations to describe a loud hissing murmur and a powerful tremulous thrill of an arteriovenous fistula.[7],[8],[9] In addition, he showed that compression in the area of the fistula caused the peripheral vessels to become smaller and the murmur to disappear.[10]
In 1808, Jean-Nicholas Corvisart translated Leopold Von Auenbrugger's latin text “Inventum Novum” from 1761. By doing so, he popularized the practice of chest percussion. He supervised several pupils, including Dupuytren, Bayle, Laënnec, and Cuvier, and he promoted his thought of diagnosing diseases through the sounds produced by the internal organs.[11],[12]
In 1809, Allan Burns published a monograph titled “Observations on some of the most frequent and important diseases of the Heart” that provided a clear and thorough description of murmurs and also detailed his views on the pathophysiology of several heart diseases.[13] He documented the cases in which audible murmurs were heard without immediate auscultation and denoted this as “audible Palpation.”[14]
Auscultation of a significant lung area was possible with direct ear application over the chest. Unable to detect the heart sounds from the narrow and constrained precordium made it more valuable for respiratory system assessment but not equally effective for cardiac auscultation. Even though it had been practised since Hippocrates' time, it was barely a suitable way to examine the patients. Because some patients were too obese or their hygiene was a problem. Modesty was an issue, particularly with female patients.[15],[16]
The Inventor and The InventionRené-Théophile-Hyacinthe Laënnec [Figure 1], a young physician of Paris turned his modesty and skills into the invention of a stethoscope to auscultate and put a cornerstone of chest diagnostics more than 200 years ago.[17]
His teachers, Corvisart and Bayle stimulated Laënnec's special interest in chest diseases, particularly tuberculosis, which was widespread in the late 18th and early 19th century considering the absence of comprehension of its contagious nature.[18] It was nicknamed “Captain of the Men of Death” because it is responsible for one in every four fatalities in Europe.[19] Laënnec had tuberculosis, and many of his family members including his mother, brother, uncle, and mentors also succumbed to the illness.[16],[19],[20],[21]
Because of its settings and beautiful surroundings, Laënnec was drawn to the Necker Hospital in Paris, and after his mentor and friend Bayle expired in 1816, he took over as chief physician.[20],[22] He got access to the numerous sources of clinical materials including the patients that he needed for his studies about chest maladies [Figure 2].[23] He correlated physical signs with autopsy findings which he alone performed on all patients demised at the Necker.[19]
Figure 2: Laënnec auscultating a tuberculous patient at the Necker Hospital. From Wellcome collection.[23]In late 1816, freshly after his graduation, he had to have a consultation with a young woman who is obese as well as give out general symptoms of underlying cardiac problems. Because of her obesity, he could not get a proper amount of information about the disease. Even though immediate auscultation will come next to mind, he is reluctant to start it.[22] He considered it inadmissible because of her modesty, age and sex as well as his shy character. In this moment of embarrassment, Laënnec recalled and got inspired by his observation of the children Sending signals to each other using a long piece of wood and a pin, which eventually led to the invention of the stethoscope.[16],[24]
“I recalled a well-known acoustic phenomenon: If you place your ear against one end of a wood beam the scratch of a pin at the other end is distinctly audible. It occurred to me that this physical property might serve a useful purpose in the case I was dealing with. I then tightly rolled a sheet of paper, one end of which I placed over the precordium and my ear to the other. I was surprised and elated to be able to hear the beating of her heart with far greater clearness than I ever had with direct application of my ear. I immediately saw that this might become an indispensable method for studying, not only the beating of the heart, but all movements able of producing sound in the chest cavity.”[25]
He was both surprised and gratified at being able to hear the heartbeats in a much clearer and more distinct manner than he had ever heard. Then he introduced the term “Auscultation” and the method of “mediate auscultation” using a stethoscope to listen to the chest, which made a revolutionary change in the art of patient care.[25] He correlated his auscultatory findings to the autopsy findings that he made at Necker Hospital.[15],[26] In 1818, Laënnec presented his discovery and potential application of his clinical tool to the Paris Academy of Sciences. And followed by that, in 1819 he published his masterpiece, “De l'auscultation médiate ou Traité du Diagnostic des Maladies des Poumon et du Coeur.”[27] He made available his wooden stethoscope to the purchaser of his book.[21],[24]
In his earlier days prior to the invention, he already found his interest in music and spent his spare time playing the flute and writing poetry. His sensitive ears as a flutist know how to listen and gave him insights to his findings.[16],[19],[21] However, this monaural device improved his as well as other physician's ability to hear clues to the underlying pathology and thus apply the appropriate treatment in many cases.[18]
He initially termed the device as “chest examiner.” He struggled to find a perfect name for his invention, discarding names such as “sonometer,” “medical cornet,” and “pectrolique.” He disliked his uncle, Guillaume-Fransois' suggestion “thoraciscoscope;” as it combined Greek and Latin words, and finally he chose the name “stethoscope,” from two Greek words overall meaning “I Look into the chest.”[18] The literal interpretation of stethoscope would be of an instrument devised for visual inspection of the thorax and it is obviously an inappropriate term. The term “stethophone,” from the Greek phonos would more accurately describe the purpose of an auscultatory device. However, the misnomer “stethoscope” has enjoyed universal usage almost without an exception.[28]
Due to the high prevalence and his dedicated work involving patients, Laënnec's health was affected by tuberculosis. He always continued to deny his condition is due to tuberculosis. By June 1826, he knew that end was approaching. The fever, productive cough and shortness of breath doesn't do any kindness to this greatest chest physician as well as the inventor who laid the cornerstone for the chest diseases. He made his last visit to his beloved countryside of Brittany and there he asked his nephew Mériadec to auscultate his chest and to describe what was heard. The auscultatory findings were alarming and similar since Laënnec heard the same sounds thousands of times before. In his will, René Laënnec bequeathed to Mériadec all of his scientific papers, as well as his watch and ring “and above all, my stethoscope, which is the best part of my legacy.”[21],[26]
Laënnec's Other ContributionsLaënnec mastered his own invention and studied many chests during his practice. Through Comparing his observations with postmortem findings, he learned to recognize various lung pathology including pneumonia, bronchiectasis, hemorrhagic pleurisy, emphysema, pneumothorax and phthisis.[16],[22],[24]
He described murmurs and thrills, pectoriloquy, egophony, bronchophony, a variety of rales, and normal and abnormal lung sounds. Along with that he also differentiated the two heart sounds during a cardiac cycle for the first time, but attributed the first heart sound to ventricular systole and the second sound to atrial systole.[16],[22] He introduced his method of “mediate (or indirect) percussion,” striking the chest with his fingers while listening with his stethoscope.[29]
Laënnec was the first to recognize that melanocytic lesions were metastatic melanoma and not the black tuberculous granulomas or carbon deposits commonly found in the lungs at autopsy. He coined the term melanose, from Greek for black, to describe these tumors.[16]
Laënnec's name would become associated with alcoholic cirrhosis of the liver. Although cirrhosis was known, Laënnec gave cirrhosis its name, using the Greek word “kirrhos” that referred to the tawny, yellow nodules that are characteristic of the disease.[30],[31] He would also be known for his published papers on peritonitis, venereal diseases, and mitral valve stenosis.[22],[24] However, his greatest contribution to medicine was undoubtedly the invention of the stethoscope. Its invention and gradual acceptance by practitioners, revolutionized the diagnosis of disease of the chest.
EvolutionAfter the invention of the stethoscope with a sheet of paper, Laënnec spent subsequent years experimenting with various materials, sizes, and shapes for his instruments. Finally, he came up with a design of 12–13 inches of long wood with a necessary aperture within them and made in two parts that can be separated.[19],[32] His illustrated model was with a funnel-shaped removable stopper which applied for heart sounds, removed for breath and adventitious sounds, and replaced for voice sounds. Woodturners quickly adapted the design and made it available to the practitioners. Wooden stethoscopes were used until the latter half of the 19th century till rubber tubing developed.[16] Although he presented his discovery to the Paris academy, the initial response was poor. Thomas Hodgkin, who eventually became a follower, learned and demonstrated this diagnostic instrument to others in London. Many experienced English physicians were unimpressed with this instrument, but students became worshipers. Those drew the attention of other European students and physicians to Paris.[21],[33]
Later in that decade, John Forbes, an English physician, translated Laënnec's book into English.[34] His motive came from his friend James Clark, who was one of the first to use the instrument. Forbes rearranged the book into two distinct papers: Pathology and diagnostics.[24],[35]
By 1826, when Laënnec came up with his latest edition with a simpler and cheaper model, the stethoscope had already gained popularity among physicians. Over the years, it commenced a role in other specialities, including obstetrics, orthopedics, and military services. Although Francois-Issac Mayor documented fetal heart sounds and their applications in 1818 by using an unaided ear, Lejumeau de Kergaradec found a role for the stethoscope in obstetrics by 1822.[36] However, Jacques Lisfranc introduced the stethoscope into orthopedics by applying it to the diagnosis of fractures.[37]
In 1828, Pierre Adolphe Piorry introduced his version by reducing its size to a finger and adding a funnel-shaped bell. His contribution is considered the first advancement in the evolution of the stethoscope. Piorry was committed to the percussion technique after being influenced by what Laënnec did for auscultation, which he described in his book “De la Percussion Médiate.”[38]
Inventors believed that if listening with one ear is good, using both ears might double the effectiveness. Thereupon they started inventing binary stethoscopes.[39] Charles James Blasius Williams, one of the followers of Laënnec, along with John Forbes, translator of Laënnec's work, became the chest physician at Brompton Hospital, which was previously known as “Hospital for Consumption and Disorders of chest.”[40] In 1843 he demonstrated his design of the binaural stethoscope with a trumpet-shaped chest end, the other end of which screwed to two bent lead pipes.[41] A modified version of this was demonstrated by Arthur Leard in 1851, with flat discs on ear pieces. Using three hands to operate this design is considered a disadvantage compared to monaural stethoscopes. In the latter half of the 19th century, when rubber tubing became available, Nathan B Marsh patented a form of the binaural stethoscope, which employed rubber tubes as earpieces. Even though it required two hands, this step was an improvement toward the modern stethoscope.[24] However, George Philip Camman was the one who got credit for designing the binaural stethoscope since he made it commercially available for practitioners by not getting patented.[42] In 1855, he documented his design with a conical chest piece connected to a hollow ball; and ivory earpieces connected to metal tubes covered with woven silk that was held together by a simple hinge joint with the tension created by an elastic band.[43] It was an improvement compared to other previous binaural stethoscopes. This model brings out more potential applications due to its utility and portability. Even though the binaural stethoscope was superior to the monaural, several physicians disliked its usage and still preferred Laënnec's original design, especially in Europe. Austin Flint, who was early to advocate the use of the stethoscope in the United States, along with Sir William Osler, popularized the binaural stethoscopes in the United States.[44]
Over the years, many contributions came from several inventors. Experimented with various materials, lengths and shapes; even tried to miniaturise them. Suggestions included a graduated stem for measuring, a rubber-shod earpiece to act as a percussion hammer, using multiple ear pieces for the purposes of teaching and the use of a membrane at the chest piece. However, not all experiments got their clinical attention.[25] In 1859, Somerville Scott Allison introduced his “original differential stethophone,” a stethoscope which allowed the practitioners to simultaneously listen to two different sounds in different parts of the chest coming through two earpieces. Although it claimed to give more information about the diagnosis, it didn't get wide acceptance. Lately, he came up with “hydrophone,” a water-filled rubber bag placed between the ear and chest, and it's helped in the augmentation of sounds. Plausibly Allison tried to correct Laënnec's misnomer by using “phono” instead of “scope” in naming the device.[28],[45],[46] In 1884, Aydon Smith came up with a model of a ultimate stethoscope with multiple purposes, which can use as a monaural, a binaural or even a differential stethoscope. The tubing serves as a tourniquet, a catheter, a stomach tube, an enema or esophageal tube: And the chest piece as an ear speculum, a funnel for administering fluids or a percussion hammer.[47]
Advancements in stethoscopes take place through modifications by various inventors. In 1894, Robert C M Bowles developed a stethoscope with a chest piece having a simple diaphragm made up of celluloid: Hard rubber used previously by others.[48] “Phonendoscope” was introduced by Bianchi and Bazzi in the same year. In addition to the augmentation of sounds, it can be used for interpreting sounds of the stomach, vagina, bladder and ear. Dual-headed chest parts have emerged lately, with the smaller side suited for use on children.[24] In 1905, Willem Einthoven, the father of electrocardiograms, contributed by transmitting heart sounds through a telephone line.[49] It was a significant breakthrough in the field of telemedicine. In 1926, Howard Sprague described a new design for a chest piece by combining a bell and a diaphragm: A “Bowles-Sprague” form of the stethoscope.[48] During the 1940s, Sprague with Maurice Rappaport studied various properties of stethoscopes, including proper fitting on ear pieces and bore and length of the tubing, Which influenced the development of modern stethoscopes in later years.[50],[51]
In 1961 David Littmann came up with the modern form of the stethoscope that we have today, presented to the Journal of American Medical Association entitled “An Approach to the Ideal Stethoscope.” According to that, an ideal stethoscope should consist of a bell for low-pitched sounds, a closed chest piece with a plastic diaphragm to filter out low pitches, and Y-shaped firm tubing with a spring to hold the ear tubes apart. Furthermore, it should be light and convenient to carry and use.[52],[53]
The stethoscope has been presented to us throughout the past 200 years in different shapes, sizes, and materials. The method of auscultation by placing the ear over the patient's chest now becomes something that could do without hesitation and the intrusion into patients' privacy. Due to digitalization and the development of technologies, electronic versions of stethoscopes are also available. Several technologies have been developed to challenge the discovery of the stethoscope, including X-ray, diagnostic ultrasounds, and computed tomography: But none of them could replace it effectively till now.[52]
End NoteThe art of auscultation was initiated in the days of Hippocrates. The initial understanding of the circulatory system and internal organs was gained through the use of this immediate auscultation technique. The journey of mediate auscultation started in 1816 when Laënnec employed a roll of paper as the first stethoscope. It is known that several experienced doctors disliked and were unimpressed with the stethoscope in its early years. The stethoscope's potential uses have been explored by innovators for the past 200 years. Major contributions made by these inventors summarized in [Table 1]. It found its place in various specialities, including obstetrics and orthopedics. Over the years, stethoscopes have also been documented for nonmedical purposes. The modern form of the stethoscope, which we mostly see today, is recommended by David Littmann. Even in this modern era of digitalisation, the stethoscope still has its own value in diagnostics. Challenges made by the new technical discoveries like echocardiogram, diagnostic ultrasounds and various other forms of diagnosis could not replace the stethoscope effectively. Imagining a doctor's or other medical professional's picture without a stethoscope around the neck seems implausible. The stethoscope is going to be a crucial diagnostic tool for a few more generations of medical students and physicians.
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Acknowledgments
I'd like to recognize the assistance that I received from Dr Rose Alphonsa George for unwavering support and proofreading the article.
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