HISTORY OF AUSCULTATION

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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

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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

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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 AY_at_ configuration
• may be internal or external

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• 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

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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

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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

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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

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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

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Correct Use

• Place chestpiece directly against patients 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

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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

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Physical Characteristics of Sound

• Three physical properties
• Frequency
• Loudness
• Harmonics 

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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 

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Intensity

• Determined by
• The amplitude of the vibrations
• Source generating the energy
• Travel distance of the vibrations
• Medium through which they travel

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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

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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.)

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THE ENDOFCHAPTER 1 2

• Tilkian, Ara MD Understanding Heart Sounds and
  Murmurs,
• Fourth Edition, W.B. Sunders Company. 2002, pp.
  1-15.