Stethoscope

An invention of a medical device

Nahrizul Adib Kadri, Raha Mat GhazaliBiomedical Engineering Programme Faculty of Engineering University of Malaya

Stethoscope An invention of a medical device

Contents Introduction Monaural stethoscope Binaural stethoscope 20th century

Stethoscope An invention of a medical device

Stethoscope An invention of a medical device

Contents Introduction Monaural stethoscope Binaural stethoscope 20th century

Stethoscope An invention of a medical device

Stethoscope An invention of a medical device

Introduction Invented by French

physician Rene Theophile Hyacinthe Laënnec in 1819

Stethoscope An invention of a medical device

A portrait of RTH Laennec

Stethoscope An invention of a medical device

Contents Introduction Monaural stethoscope Binaural stethoscope 20th century

Stethoscope An invention of a medical device

Stethoscope An invention of a medical device

Monaural stethoscope 1816 Laennec was examining

a young female patient He was embarrassed to place

his ear to her chest Rolled up 24 sheets of paper,

placed one end to his ear and the other end to the woman’s chest

Discovered that the sounds were also louder and clearer

Laennec examining a patient

Stethoscope An invention of a medical device

Monaural stethoscope (cont.) Laennec preferred to have his

instrument simply called Le Cylindre, since he thought naming such an instrument was unnecessary

Later decided to call stethoscope, derived from the Greek words for I see, and the chest A replica of Laennec’s stethoscope

Stethoscope An invention of a medical device

Monaural stethoscope (cont.) Laennec set up a small shop,

with a wood-turning lathe and many different materials

He created a stethoscope from a turned piece of wood, hollow in the center, made of two pieces

One end had a hole to place against the ear, and the other was hollowed out into a cone

Laennec stethoscope, circa 1830

Stethoscope An invention of a medical device

Monaural stethoscope (cont.) 1828 Piorry incorporated

pleximeter into his stethoscope His model about half the size of

Laennec’s - made of wood with removable ivory earpiece and chest piece

Combined Laennec-Piorry stethoscope

Stethoscope An invention of a medical device

Monaural stethoscope (cont.) 1828 C J B Williams used a

two-piece monaural with removable end piece for examining the lungs

Much smaller and more convenient instrument

William’s stethoscope, circa 1845

Stethoscope An invention of a medical device

Monaural stethoscope (cont.) Other examples:

Cedar stethoscope with curved earpiece

Separable stethoscope

Flexible stethoscope

Stethoscope An invention of a medical device

Monaural stethoscope (cont.) Eventually physicians decided

to find out if an instrument using both ears would be better – began quest for binaural stethoscope

Stethoscope An invention of a medical device

Contents Introduction Monaural stethoscope Binaural stethoscope 20th century

Stethoscope An invention of a medical device

Stethoscope An invention of a medical device

Binaural stethoscope 1829 Nicholas

Comins suggested a binaural stethoscope

Described a stethoscope as a bent tube with several hinges

Allowing physician not to assume uncomfortable positions during the examination

1851 Dr Marsh developed first commercial model

Contained the first diaphragm chest piece

Bulky and cumbersome

Stethoscope An invention of a medical device

Binaural stethoscope (cont.) 1855 Dr George Cammann

produced the first usable binaural stethoscope

Model - ivory earpieces connected to metal tubes, two tubes covered with wound silk, hollow ball to amplify the sound, bell-shaped chest piece

Dr Cammann’s stethoscope

Stethoscope An invention of a medical device

Binaural stethoscope (cont.) 1863 Scott Alison improved

Dr Cammann’s stethoscope - differential stethoscope

Two independent chest pieces, to allow the listener to compare the sounds of two areas of the chest

Impractical because it muffled certain sounds

Differential stethoscope, circa 1870

Stethoscope An invention of a medical device

Binaural stethoscope (cont.) 1882 Bartlett made another

improvement - Bartlett's Laennec stethoscope

Used metal ear-tubes with the silk covered rubber tubes leading to a wooden chest piece

Bartletts’ stethoscope, circa 1880

Stethoscope An invention of a medical device

Binaural stethoscope (cont.) 1885 Charles Denison came

out with a new model, based on Bartlett's

Came with three interchangeable chest pieces for hearing different types of sounds

Denison’s sthetoscope

Stethoscope An invention of a medical device

Binaural stethoscope (cont.) 1885 invention of the Ford's

Bell chest piece Funneled sound into two

tubes, usually made of rubber, which led to the earpieces

Snofton's stethoscope incorporating a Ford's Bell chest piece, circa 1890

Stethoscope An invention of a medical device

Binaural stethoscope (cont.) Other examples: Sheppard's folding stethoscope, circa 1890

Leared's stethoscope

Stethoscope An invention of a medical device

Contents Introduction Monaural stethoscope Binaural stethoscope 20th century

Stethoscope An invention of a medical device

Stethoscope An invention of a medical device

20th century (cont.) The bell chest piece was

great for low-pitched sounds, however need to hear higher pitched sounds - enter the diaphragm chest piece

The diaphragm became the standard for modern stethoscopes

Early stethoscope with diaphragm

Stethoscope An invention of a medical device

20th century (cont.) The stethoscope has

remained unchanged since 1930's

There were several experimental stethoscopes, including symballophone by Dr William Kerr

Dr Kerr’s symballophone

Stethoscope An invention of a medical device

20th century (cont.) The newer models have both

the bell and diaphragm interchangeable in the same chest piece

Rieger-Bowles Stethoscope

Fleisher stethoscope

Dr Kehler’s stethoscope

Stethoscope An invention of a medical device

20th century (cont.) Latest models:

Littmann Cardiology III stethoscope

Welch Allyn electronic stethoscope

Stethoscope An invention of a medical device

TheThank you for your attention

End