The Stethoscope

The doctor's chest-examiner

Before the development of the stethoscope, doctors placed their ears directly on the patient's body so the action of the heart and other organs of the chest can be heard and gauged.

That was soon to change when French physician Rene Theophile Hyacinthe Laennec invented an instrument in 1816. At first he used simple paper cylinders to listen to his patients. Later he developed this into an instrument consisting of a hollow wood tube that flared at both ends. He held the smaller end to his ear and placed the other end against the patient's chest.

The stethoscope we know today is biaural. It is still used to listen to the internal sounds of the body, particularly of the heartbeat and respiratory organs, but with greater effect.

Essentially it consists of two flexible, hollow tubes (usually rubber), which at one end are attached to a single metal cup (sounding device) and at the other to a pair of earpieces. The metal cup, which is highly sensitive to sound and vibration, is placed against the body. Sounds are transferred along the hollow tubes to the examiner's ears with minimal outside disturbance.

History of the Stethoscope

Stethoscope is an instrument that enables a physician to hear the sounds made by the internal organs of the body. The stethoscope is most commonly used to listen to the sounds of the heart and lungs, but it may also be used to detect sounds arising from the blood vessels, intestines, and other organs. Auscultation, or listening to the sounds of functioning organs, enables a physician to detect many kinds of disorders and is an important part of every physical examination.

In the fourth century B.C. attention was called by Hippocrates, who was regarded as the father of medicine, to a splashing noise which could be heard on shaking a patient who had pus in his chest (empyema). This method was not carried further until 1761, when the Viennese physician Leopold Auenbrugger published his great treatise on percussion. By tapping with a finger of the right hand one of the fingers of the left hand placed in contact with the patient's skin, the physician could now define with considerable accuracy the size of certain organs in the body; he could also deduce the presence of abnormal collections of gas or fluids.

Early in the nineteenth century physicians of the French School began to study the sounds which are themselves produced in the body, as for example the breath-sounds in the lungs and the sound of the heart beating. For this purpose the physician placed his ear on the patient's skin over the organ to be studied. This method was known later as 'immediate auscultation'. It is significant that as late as 1806, Corvisart des Maret, Napoleon's physician and one of the greatest authorities in Europe on diseases of the heart, could talk of hearing the heart beat 'several times' when he listened very close to the chest. For several reasons immediate auscultation was not very satisfactory.

The complementary and more valuable method of 'mediate auscultation' was introduced by the Parisian physician Rene Theophile Hyacinthe Laennec (1781-1826) who invented the stethoscope (Greek stethos, 'chest'; skopeo, 'I see, examine') which is now so familiar a part of the doctor's equipment. Laennec had used the older method - direct application of the ear to the chest - but was dissatisfied with the results. In 1816, as he tells us, he was consulted by a young woman suffering from heart disease, in whose case the older method could not be used. Laennec remembered that he had once noticed a group of children playing among felled tree trunks. He had seen one of them scratching the wood at one end of the log and the rest listening at the other end. So he now rolled a quire of paper into a cylinder and applied one end of it to the region of the patient's heart and the other end to his own ear. He found that he could hear the heart sounds much more clearly than he had ever done before.

Laennec began to experiment on the construction of stethoscopes, using paper cylinders, wood, cane, glass, and several metals in turn. In the end he adopted the experimental model which is known as Laennec's stethoscope and which consisted of a cylinder of wood, one and a half inches in diameter and about ten inches in length. A hole about £ inch in diameter traversed the cylinder throughout its length, and at the lower end opened out into a conical cavity. This cavity could be filled by an accurately fitting plug, which was itself bored to continue the main hole running through the cylinder. For convenience the cylinder was divided into two approximately equal parts, one being shaped to plug into the other. Laennec published his description of this instrument in 1817, and with it he carried out a most extensive series of observations in many diseases of the heart and lungs. He invented most of the terms for the sounds heard which are still used at the present day. His great work on 'mediate auscultation' - that is, auscultation by the aid of the stethoscope intervening between the ear and the patient's skin -was published in 1819. Diagnosis of diseases of the chest was completely revolutionized.

Laennec's instrument was soon modified. Lighter stethoscopes were made in the shape of a dumb-bell, shortened to five inches, and in the shape of a trumpet with a bell-shaped chest-piece ; some were made to fit in the pocket or inside the doctor's top-hat. In one form of stethoscope the stem was attached to the ear-piece by a short length of stiff rubber tubing - this was the instrument which enabled a character in Washington Square (1881) by Henry James to listen to his own heart.

All these stethoscopes were of the 'monaural' type. The 'binaural' or two-eared stethoscope began with an experimental form made in 1829 by a London doctor who used flexible lead pipes. Rubber tubing was developed and in 1855 Dr Cammann of New York described the first bin-aural stethoscope to be manufactured and marketed. The binaural instrument did not come into general favour in Great Britain until the eighteen-eighties.

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Comments 3 comments

Silver Freak profile image

Silver Freak 7 years ago from The state of confusion

Thanks for helping me learn something new today. Great history lesson!


darkside profile image

darkside 7 years ago from Australia Author

I think they should further the development by having a little heater inside the metal head. Those things are cold!


Iphigenia 7 years ago

I've never really thought about stethoscopes and how thet were developed - but this is a fascinating outline of how observation and development resulted in a crucial piece of medical equipment.

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    References

    • People, Places and Things, Volume 3, The Waverley Book Company Limited, 1954
    • Merit Students Encyclopedia, Volume 17, P.F. Collier Inc, 1979. Page 430
    • Pears Cyclopaedia, Twenty-Ninth Edition, 1926. Page 267
    • New Knowledge Library - Universal Reference Encyclopedia, Volume 29, Bay Books, 1981. Page 2711.
    • Image Source: http://www.morguefile.com/archive/display/16561

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