1. Stethoscope An invention of a medical device Nahrizul Adib Kadri, Raha Mat Ghazali Biomedical Engineering Programme Faculty of Engineering University of Malaya

2. Stethoscope An invention of a medical device Contents Introduction Monaural stethoscope Binaural stethoscope 20 th century Stethoscope An invention of a medical device

3. Contents Introduction Monaural stethoscope Binaural stethoscope 20 th century Stethoscope An invention of a medical device

4. Introduction Invented by French physician Rene Theophile Hyacinthe Laënnec in 1819 Stethoscope An invention of a medical device A portrait of RTH Laennec

5. Stethoscope An invention of a medical device Contents Introduction Monaural stethoscope Binaural stethoscope 20 th century Stethoscope An invention of a medical device

6. 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

7. 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

8. 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

9. 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

10. 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

11. Stethoscope An invention of a medical device Monaural stethoscope (cont.) Other examples: Cedar stethoscope with curved earpiece Separable stethoscope Flexible stethoscope

12. 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

13. Stethoscope An invention of a medical device Contents Introduction Monaural stethoscope Binaural stethoscope 20 th century Stethoscope An invention of a medical device

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. Stethoscope An invention of a medical device Binaural stethoscope (cont.) Other examples: Sheppard's folding stethoscope, circa 1890 Leared's stethoscope

21. Stethoscope An invention of a medical device Contents Introduction Monaural stethoscope Binaural stethoscope 20 th century Stethoscope An invention of a medical device

22. 20 th 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

23. Stethoscope An invention of a medical device 20 th 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

24. Stethoscope An invention of a medical device 20 th 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

25. Stethoscope An invention of a medical device 20 th century (cont.) Latest models: Littmann Cardiology III stethoscope Welch Allyn electronic stethoscope

26. Stethoscope An invention of a medical device The Thank you for your attention End