1. HISTORY OF AUSCULTATION
400 BC. Basic concept of auscultation by Hippocrates
1818 Rene Laennec invented the stethoscope
1828 Pierre Piorry first advance in developing a stethoscope that broke down into two parts
1829 Dr Nicholas Comins design the first flexible monaural stethoscope
1829 Charles Williams created the binaural Stethoscope without earpieces

2. HISTORY cont…
1852 Dr. George Cammann created the modern form of the binanual stethoscope with ear plugs
1858 Scott Alison developed the differential stethoscope for auscultation of heart and lung sounds
1862 Dr. Austin Flint was the first to use the Binaural Stethoscope in the USA. He first described the famous murmur of aortic insufficiency that mimics mitral stenosis the Austin Flint Murmur

3. The Modern Stethoscope
COMPONENTS
Earpiece
just large enough to cover the external ear canal/same plane/angled slightly forward
needs a good seal, airtight system
 Binaurals
a connection for the two earpieces
may be flexed to provide maximum comfort
Metal brace / spring
protects tubing at the configuration
may be internal or external

4. Tubing
Internal bore and walls of .3 cm transmits sounds best and is broad enough not to occlude the tubing when slightly bent.
May be single or double
Plastic or vinyl material
Semi-rigid / thick walls (reduce noise / no occlusion when bent)
10 to 12 inches in length (longer may cause high frequency sounds to be diminished)
Molded all in one piece and is not assembled from three fragments by a plastic adapter
Lumen of the tubing should be smaller at the bell than at the binaurals

5. The Chestpiece Diaphragm of the stethoscope Physical Characteristics
Diaphragm chestpiece should be about 4 cm in diameter and .3 to .4 mm in thickness.
Check periodically for cracks or tears, which cause a diminished transmission of sound

6. The Chestpiece cont Best Use
Detecting high-frequency (high-pitched sounds and murmurs
Filters out the lower frequency sounds
Applied to chest with firm pressure
Sounds/murmurs best heart
1st & 2nd heart sounds
Their splitting, ejection sounds, systolic clicks, the opening snaps of mitral or tricuspid stenosis
Diastolic murmurs of aortic or pulmonic valve regurgitation
Systolic murmur of VSD

7. The Chestpiece cont.. The bell of the stethoscope
Physical Characteristics
Not less than 2.5 cm in diameter for adults so that it can span an intercostal space
It should be deep enough so that, when applied with light pressure, the bell chamber will not be obliterated by tissue

8. The Chestpiece cont.. Best use of the Bell
Detecting the faintest low-pitched and medium-pitched sounds and murmurs
Applied gently to the skin with as light a pressure as possible so as to barely make an air seal
Diastolic rumbles of mitral and tricuspid stenosis
3rd & 4th heart sounds
1st & 2nd heart sounds

9. Correct Use Place chestpiece directly against patient’s skin
Diaphragm chestpiece should be applied with enough pressure to leave a slight depression when removed
Excessive pressure may obstruct vessel blood flow (loss of sound, false bruits)
Fingers holding chestpiece should remain straight still (movement may cause extraneous noise)
Avoid stretching the tube

10. Care of the Stethoscope
Inspect tubing for holes or cracking
Inspect diaphragm for cracks or tears
Each of the above problems, if found, may cause diminished sounds!
Never use alcohol on the tubing (may dry and cause cracking)
Unscrew diaphragm from holder and cleanse with soap & water, dry
Soak eartips in soapy water, rinse & dry
ID bands / tape may interfere with transmission of sound
Engrave name on back of diaphragm

11. Physical Characteristics of Sound
Three physical properties:
Frequency
Loudness
Harmonics 

12. Frequency
A measure of the number of vibrations (cycles / second) or Hertz (Hz)
The greater the number of vibrations the higher frequency the sound
High frequency = high pitch
Low frequency = low pitch 

13. Intensity Determined by: The amplitude of the vibrations
Source generating the energy
Travel distance of the vibrations
Medium through which they travel

14. Harmonics
 Relates to quality, mixture of frequencies, and duration of vibrations
 Short vibrations are classified as clicks or snaps
Longer vibrations are classified as murmurs

16. The Examination Optimize your environment for auscultation
Obtain a quiet room for assessment
Close doors, turn any radio / TV off
Ask politely to abstain from conversation while auscultating
Focus on one characteristic at a time
Actual components (S1, S2, etc.)

17. THE END OF CHAPTER 1 & 2
Tilkian, Ara MD Understanding Heart Sounds and Murmurs,
Fourth Edition, W.B. Sunders Company. 2002, pp