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

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

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@ configuration may be internal or external

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

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

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

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

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

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

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

Physical Characteristics of Sound Three physical properties: Frequency Loudness Harmonics 

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 

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

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

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.)

THE END OF CHAPTER 1 & 2 Tilkian, Ara MD Understanding Heart Sounds and Murmurs, Fourth Edition, W.B. Sunders Company. 2002, pp. 1-15.