1819 __ Stethoscope — an instrument of listening
‣ Comment : Auscultation - act of listening. Buisson has used it synonymously with "listening". Laënnec introduced "auscultation" to appreciate the different sounds, which can be heard in the chest, and in the diagnosis of diseases of the heart, lungs, etc. This may be done by the aid of an instrument called a "stethoscope", one extremity of which is applied to the ear, the other to the chest of the patient. This mode of examination is called "Mediate Auscultation", (F) Auscultation médiate - the application of the ear to the chest being "immediate auscultation". The act of exploring the chest is called "Stethoscopia", and "Thoracoscopia" ; of the abdomen, "Abdominoscopia". (Robley Dunglison, p. 83, 1845) — Assessing the sounds of the human body was reported in the ancient medical literature. Amongst the earliest known medical manuscripts are the medical papyruses of ancient Egypt dating to the seventeenth century B.C. The Egyptians were one of the first civilizations to systematically document the practice medicine. The first recognized physician was the Egyptian priest Imhotep, who many consider to be the true father of medicine. The Edwin Smith Papyrus (seventeenth century B.C.) and the Georg Ebers Papyrus (sixteenth century B.C.) are an instructional system of the diagnosis and practice of medicine, which referred to audible signs of disease within the body. A millennium later, Soranus of Ephesus identified uterine disease by sound produced when the hand pressed on the abdomen. [...] Hippocrates, the Father of Medicine, advocated for the search of philosophical and practical instruments to improve medicine in 350 B.C. He, in fact, discussed a procedure for shaking a patient by the shoulders (succussion) and listening for sounds evoked by the chest. Hippocrates also used the method of applying the ear directly to the chest and found it useful in order to distinguish between the accumulation of water and pus within the chest. Water bubbled like "simmering vinegar." Caeleus Aurelianus listened to the chest in A.D. 200 by placing his ear in direct contact with it in order to diagnose bronchitis. And Aretaeus of Cappadonia described abdominal sounds in dropsy as being drum like (tympanic). Despite the return to mysticism in medicine in the Dark Ages, paintings in the Middle Ages depicted physicians examining patients by placing the unaided ear to the chest. In the sixteenth century, the renown surgeon Ambroise Pare noted that "if there is matter or other humors in the thorax, one can hear a noise like that of a half filled gurgling bottle." The distinguished scientist William Harvey, in his 1616 lecture on the structure and function of the heart, described the heart's motion as "two clacks of a water-bellows to rayse water" and noted that "with each movement of the heart, when there is delivery of a quantity of blood from the veins or arteries, a pulse takes place and can be heard within the chest." And the physiologist Robert Hooke speculated in the 1700s after listening to the beating heart "who knows, I say, but that it may be possible to discover the Motion of the Internal Parts of Bodies....by the sound they make; that one may discover the Works performed in the several offices and shops of a Man's Body, and thereby discover what Instruments or Engine is out of order." Joseph Leopold Auenbrugger provided the first comprehensive description of percussion of the chest in his 1761 monograph. He began to employ percussion in 1754 as a physician at the Spanish Hospital in Vienna and attributed his discovery to his boyhood experience of watching his father tapping to determine the fluid level in kegs. Auenbrugger tapped the patients with his fingertips with the hand drawn closed to determine the point where percussion detected an abnormality. He described the sounds as either high pitched, muted or dull. The Vienna physician Maximilian Stoll wrote about percussion in 1786 and the French physician M. Roziere de la Chassagne of the Medical Faculty of Montpelier published a French translation of Auenbrugger's work in 1770. But percussion never received general acceptance. It was Jean Nicholas Corvisart, the prominent French physician, physician to Napoleon Bonaparte, and teacher of Laënnec, who moved percussion into the mainstream of medical practice. Corvisart adapted Auenbrugger's technique by using the planar surface of his fingers to strike the chest. He published a French translation of Auenbrugger's text in 1808, which was widely read. John Forbes of England translated the text into English in 1824, using original case observations to illustrate the usefulness of percussion. Collin in his 1824 monograph on respiration devoted a chapter to percussion. He preferred slight tapping with a stethoscope as the best means of producing the percussed sound, perhaps reflecting the fact that he was an assistant to Laënnec who used this technique. It was A.D. Piorry who introduced in 1826 the use of a solid piece of material, usually ivory, as a pleximeter to improve the quality of sound as a result of tapping the pleximeter placed firmly against the chest ( mediate percussion ) rather than the chest wall itself ( immediate percussion ). He adapted the stethoscope to include a pleximeter and published his inventions in 1828. In Germany, Wintrich introduced the first percussion hammer in 1841. By this time percussion had become an accepted diagnostic modality. Rene T.H. Laënnec's teacher Corvisart was accustomed to placing his ear over the cardiac region of the chest to listen to the heart. Bayle and Double, who like Laënnec were students of Corvisart, used the unaided ear to listen to the heart of their patients. Double suggested the regular use of this technique in his treatise on Semiologie published in 1817. Nevertheless, the evolution from listening with the unaided ear ( immediate auscultation ) to the aided ear ( mediate auscultation) awaited Laënnec's invention of the stethoscope in 1816. Laënnec himself recounts that he recollected the "augmented impression of sound when conveyed through certain solid bodies as when we hear the scratch of a pin at one end of a piece of wood, on applying our ear to the other." Laënnec, therefore, "rolled a quire of paper in sort of a cylinder and applied one end of it to the region of the heart and the other end 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 has ever been able to do so by the immediate application of the ear." Laënnec continued his study of mediate auscultation with the stethoscope at the Hopital Necker in Paris and published his observations in his classic text on mediate auscultation in 1819. Interestingly, Laënnec does not mention in the first edition of his text the experiment of the famous physicist and physician W.H. Wollaston, who in 1810 reported using a long notched stick resting on his foot with his ear resting on the other end to count the sounds of muscle contraction in his foot. Initially, Laënnec simply called his invention "le cylindre", but later chose the name stethoscope from the Greek words stethos (chest) and scope (to look at). John Forbes, who translated Laënnec's text into English in 1821, first applied the Latin word auscultation (to hear) to the practice of medicine. Laënnec described the different sounds produced in the chest cavity by the movement of air, movement of lung tissue, accumulation of lung fluid, reverberation of the voice and beating of the heart. Mediate auscultation with the stethoscope was accepted slowly into medical practice during the remainder of the nineteenth century. By the twentieth century, inspection, palpation, percussion and auscultation became the standard physical diagnostic approach to examining a patient and remains so today. In the end, the stethoscope became the symbol of the learned physician because it enabled doctors to hear the signs of patients' respiratory and circulatory diseases. (Eric Rackow, “A BRIEF HISTORY OF PHYSICAL DIAGNOSIS”) — The stethoscope (from Greek στηθοσκόπιο, of στήθος, stéthos - chest and σκοπή, skopé - examination) is an acoustic medical device for auscultation, or listening to the internal sounds of an animal body. It is often used to listen to lung and heart sounds. It is also used to listen to intestines and blood flow in arteries and veins. In combination with a sphygmomanometer, it is commonly used for measurements of blood pressure. Less commonly, "mechanic's stethoscopes" are used to listen to internal sounds made by machines, such as diagnosing a malfunctioning automobile engine by listening to the sounds of its internal parts. Stethoscopes can also be used to check scientific vacuum chambers for leaks, and for various other small-scale acoustic monitoring tasks. A stethoscope that intensifies auscultatory sounds is called phonendoscope. The stethoscope was invented in France in 1816 by René Laënnec at the Necker-Enfants Malades Hospital in Paris. It consisted of a wooden tube and was monaural. His device was similar to the common ear trumpet, a historical form of hearing aid; indeed, his invention was almost indistinguishable in structure and function from the trumpet, which was commonly called a "microphone". In 1851, Arthur Leared invented a binaural stethoscope, and in 1852 George Cammann perfected the design of the instrument for commercial production, which has become the standard ever since. Cammann also authored a major treatise on diagnosis by auscultation, which the refined binaural stethoscope made possible. By 1873, there were descriptions of a differential stethoscope that could connect to slightly different locations to create a slight stereo effect, though this did not become a standard tool in clinical practice. Acoustic stethoscopes are familiar to most people, and operate on the transmission of sound from the chest piece, via air-filled hollow tubes, to the listener's ears. The chestpiece usually consists of two sides that can be placed against the patient for sensing sound. — a diaphragm (plastic disc) or bell (hollow cup). If the diaphragm is placed on the patient, body sounds vibrate the diaphragm, creating acoustic pressure waves which travel up the tubing to the listener's ears. If the bell is placed on the patient, the vibrations of the skin directly produce acoustic pressure waves traveling up to the listener's ears. The bell transmits low frequency sounds, while the diaphragm transmits higher frequency sounds. This 2-sided stethoscope was invented by Rappaport and Sprague in the early part of the 20th century. One problem with acoustic stethoscopes was that the sound level is extremely low. This problem was surmounted in 1999 with the invention of the stratified continuous (inner) lumen, and the kinetic acoustic mechanism in 2002. Acoustic stethoscopes are the most commonly used. A recent independent review evaluated 12 common acoustic stethoscopes on the basis of loudness, clarity, and ergonomics. They did acoustic laboratory testing and recorded heart sounds on volunteers. The results are listed by brand and model. An electronic stethoscope (or stethophone) overcomes the low sound levels by electronically amplifying body sounds. However, amplification of stethoscope contact artifacts, and component cutoffs (frequency response thresholds of electronic stethoscope microphones, pre-amps, amps, and speakers) limit electronically amplified stethoscopes' overall utility by amplifying mid-range sounds, while simultaneously attenuating high- and low- frequency range sounds. Currently, a number of companies offer electronic stethoscopes. Electronic stethoscopes require conversion of acoustic sound waves to electrical signals which can then be amplified and processed for optimal listening. Unlike acoustic stethoscopes, which are all based on the same physics, transducers in electronic stethoscopes vary widely. The simplest and least effective method of sound detection is achieved by placing a microphone in the chestpiece. This method suffers from ambient noise interference and has fallen out of favor. Another method, used in Welch-Allyn's Meditron stethoscope, comprises placement of a piezoelectric crystal at the head of a metal shaft, the bottom of the shaft making contact with a diaphragm. 3M also uses a piezo-electric crystal placed within foam behind a thick rubber-like diaphragm. Thinklabs' Rhythm 32 inventor, Clive Smith uses an Electromagnetic Diaphragm with a conductive inner surface to form a capacitive sensor. This diaphragm responds to sound waves identically to a conventional acoustic stethoscope, with changes in an electric field replacing changes in air pressure. This preserves the sound of an acoustic stethoscope with the benefits of amplification. Because the sounds are transmitted electronically, an electronic stethoscope can be a wireless device, can be a recording device, and can provide noise reduction, signal enhancement, and both visual and audio output. Around 2001, Stethographics introduced PC-based software which enabled a phonocardiograph, graphic representation of cardiologic and pulmonologic sounds to be generated, and interpreted according to related algorithms. All of these features are helpful for purposes of telemedicine (remote diagnosis) and teaching. Some electronic stethoscopes feature direct audio output that can be used with an external recording device, such as a laptop or MP3 recorder. The same connection can be used to listen to the previously-recorded auscultation through the stethoscope headphones, allowing for more detailed study for general research as well as evaluation and consultation regarding a particular patient's condition and telemedicine, or remote diagnosis. A fetal stethoscope or fetoscope is an acoustic stethoscope shaped like a listening trumpet. It is placed against the abdomen of a pregnant woman to listen to the heart sounds of the fetus. The fetal stethoscope is also known as a Pinard's stethoscope or a pinard, after French obstetrician Adolphe Pinard (1844-1934). (Compiled from various sources)
‣ French comment : Les parties osseuses de la tête conduisent le son à l’oreille avec une facilité très grande. On peut ainsi entendre par le front, les dents, etc. Deux personnes qui parlent très bas en tenant entre leurs dents les deux extrémités dune longue tige de bois ou d’un fil tendu, s’entendent à une distance considérable; le résultat est le même su la personne qui parle appuie la tige sur sa gorge ou sur sa poitrine. C’est sur les mêmes principes que repose le stéthoscope, inventé par Laënnec en 1819; il se compose essentiellement d’un cylindre de bois que le médecin appuie sur la poitrine du malade, afin de mieux entendre les bruits du cœur; cela s’appelle “ausculter”. [...] Lorsqu’on frappe sur une cuiller d’argent, un timbre de verre ou tout autre corps sonore suspendu à un fil dont on introduit l’extrémité libre dans le conduit auditif (on peut aussi la saisir entre les dents et se boucher les oreilles), on entend un son grave et plein comme celui d’un bourdon éloigné. Un médecin danois, Herhold, a fait cette expérience avec une cuiller attachée à un fil d’une longueur de 200 mètres, dont une extrémité était fixée à un pieu pendant qu’on tenait l’autre avec les dents. (R. Radau, p. 58) — « [Dans le cas du stéthoscope] la longueur des tubes peuvent aller à 4 mètres et plus sans que le son paraisse affaibli. Avec ce stéthoscope, un médecin pourrait donc, sans sortir de son cabinet, entendre les battements de cœur d’un malade qui se trouverait à plusieurs étages au-dessous. ». (Rodolphe Radau, p. 87) — L’idée peut paraître simple : en remplissant leurs fonctions, les organes humains émettent des bruits, “normaux” si les organes sont sains, “modifiés” s’ils sont malades. Laënnec a tout de suite imaginé le parti que l’on pouvait tirer du phénomène de transmission des sons, amplifiée, à partir d’une surface limitée et choisie, par l’intermédiaire d’un corps solide. [...] Pour les patients qui décèdent, environ un sur cinq entrants soit 400 par an environ, un tableau des concordances entre les constats de l’auscultation et ceux de la nécropsie est établi. En fonction de la transmission des bruits de la respiration, de la voix, de la toux, des bruits surajoutés, des bruits cardiaques, un diagnostic provisoire est porté : on va contrôler que ce que l’on a entendu correspondait bien à l’hypothèse clinique, vérification à l’appui en salle de dissection. En moins de dix-huit mois, Laënnec et les siens accroissent leur performance quant à l’exactitude des leurs prévisions. Tous les malades seront “auscultés” dès la mi-1817. Le mot, issu du verbe lation qui signifie “écouter”, n’est pas nouveau. Hippocrate songeait déjà à faire appliiquer l’oreille du médecin contre la poitrine du malade (auscultation dite immédiate). Laënnec et Bayle la pratiquaient de temps à autre avec des constatations confuses, peu utiles, voire impossibles (sous les aisselles). Ce n’était pas commode, ni pour le malade, ni pour le médecin, sans parler des difficultés liées à la pudeur, à l’hygiène ou au volume des seins. Le nouvel outil, lui, limite et sélectionne la surface d’écoute et, surtout, il décuple la finesse de la perception auditive du médecin. Dès 1802, à l’âge de vingt-et-un ans, Laënnec avait rendu compte d’une publication de son collègue [Matthieu-François-Régis] Buisson sur la perception de la voix humaine. Ce dernier distinguait la différence entre le fait d’entendre, ou audition, phénomène passif, et celui d’écouter, ou auscultation, phénomène actif. Au terme “auscultation”, Laënnec ajoute l’épithète “médiate”, et à l’instrument médiateur, il donne le nom de “stéthoscope”, du grec “stéthos”, poitrine, et “skopein”, observer par la vue. (Étienne Subtil, “René Théophile Laënnec, ou la passion du diagnostic exact”, pp. 49-50, 2006)
‣ Original excerpt : « 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 (chest) 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. » (Translated from French by John Forbes, 1834, In Jay V. “The legacy of Laënnec”. Arch Pathol Lab Med 2000;124:1420–1421 ; and also : Davies MK, Hollman A. Rene Theophile-Hyacinthe Laënnec 1781–1826 Heart 1996;76:196 ; Welsby PD, Parry G, Smith D.)
‣ Source : Radau Rodolphe (1867). “L’Acoustique ou les Phénomènes du Son”. Coll. « Bibliothèque des Merveilles » sous la direction de M. Édouard Charton. Paris : Librairie Hachette.
‣ Source : R. Dunglison. (1845). “Medical lexicon: a dictionary of medical science : containing a concise account of the various subjects and terms, with the French and other synonymes, notices of climate, and of celebrated mineral waters, formulae for various officinal and empirical preparations, etc,". Fifth edition. Philadelphia : Lea and Blanchard.
‣ Source : R.-T.-M.-H. Laënnec. (1819). Traité de l’auscultation médiate, ou Traité du diagnostic des maladies des poumons et du cœur, fondé principalement ur ce nouveau mode d’exploration. Paris : Chez J.A. Brosson & J.S. Chaudé, 1837.
‣ Urls : http://www.youtube.com/watch?v=nnfbOVjG3_4 (last visited ) http://www.antiquemed.com/invention.html (last visited ) http://www.synesthesie.com/zoom.php?texteId=1541 (last visited )
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