Stethoscope

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

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

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

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

5. Contents • Introduction • Monaural stethoscope • Binaural stethoscope • 20th 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. 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. 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. 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. 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. Monaural stethoscope (cont.) • Other examples: Separable stethoscope Flexible stethoscope Cedar stethoscope with curved earpiece

12. Monaural stethoscope (cont.) • Eventually physicians decided to find out if an instrument using both ears would be better – began quest for binaural stethoscope

13. Contents • Introduction • Monaural stethoscope • Binaural stethoscope • 20th 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. 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. Binaural stethoscope (cont.) Differential stethoscope, circa 1870 • 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

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

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

22. 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

23. 20th century (cont.) • The stethoscope has remained unchanged since 1930's • There were several experimental stethoscopes, including symballophoneby Dr William Kerr Dr Kerr’s symballophone

24. 20th century (cont.) • The newer models have both the bell and diaphragm interchangeable in the same chest piece Dr Kehler’s stethoscope Rieger-Bowles Stethoscope Fleisher stethoscope

25. 20th century (cont.) • Latest models: Littmann Cardiology III stethoscope Welch Allyn electronic stethoscope

26. The Thank you for your attention End