It consisted of a wooden tube and was monaural. His device was similar to the common ear trumpet, a historical form of hearing aid; indeed, his invention was almost indistinguishable in structure and function from the trumpet, which was commonly called a "microphone." In 1851 Arthur Leared invented a binaural stethoscope, and in 1852 George Cammann perfected the design of the instrument for commercial production, which has become the standard ever since. Cammann also authored a major treatise on diagnosis by auscultation, which the refined binaural stethoscope made possible. By 1873, there were descriptions of a differential stethoscope that could connect to slightly different locations to create a slight stereo effect, though this did not become a standard tool in clinical practise.

Rappaport and Sprague designed a new stethoscope in the 1940s which became the standard by which other stethoscopes are measured. The Rappaport-Sprague was later made by Hewlett-Packard, later Philips, and today there are still cardiologists who consider it to be the finest acoustic stethoscope.^{[citation
needed]} Several other minor refinements were made to stethoscopes until in the early 1960's Dr. Littmann, a Harvard Medical School professor, created a new stethoscope that was lighter than previous models.

q Identify the parts of a stethoscope including the tubing, earpiece, and chestpiece.

q Describe the various types of stethoscopes and the advantages and disadvantages of each type.

q Describe the purpose and use of voice sounds such as bronchophony, egophony and whispered pectoriloquy.

q Discuss various ways to improve your abilities to perform and improve auscultation techniques.

ØUse the finger of a glove over the diaphragm

I. Introduction to the Stethoscope

A. Earpiece

1. Soft and supple

2. Should seal completely

3. Made of different material

4. Choose what is comfortable to you

5. Clean frequently with alcohol

B. Tubing

1. Plastic or rubber

2. 10-15” long

3. Twin tube or mono

4. Latest are ones acoustically superior

C. Chestpiece

1. Diaphragm

2. Bell

3. Dual headed

4. Enhanced

5. Amplified

6. Recording

II. Types of Stethoscopes

A. El-Cheap-o

1. Single headed (diaphragm only)

2. Disposable (should be anyway)

3. Not the best sound quality

4. Some are actually dual headed!

B. Sprague Rappaport

1. Great starter stethoscope

2. Twin tubes

3. Dual headed (5 in one!)

4. Less than $20.00

C. Professional Quality

1. Littman

a) Classic II

b) Master Classic

c) Cardiology III

d) Master Cardiology

2. DRG (Doctor’s Research Group)

a) Puretone Classic

b) Puretone Cardiology

3. ADC and others

a) Comparable quality

b) Less expensive

D. Other Specialty Scopes

1. Cardioscope

2. Doppler

3. Aided sound

III. Use of the Stethoscope

A. How to wear it

1. ear canals go forward

2. so should stethoscope

B. Using it on someone

1. direct skin contact

2. warm up the scope

3. optimize the environment

4. concentrate!

C. Diaphragm vs. Bell

1. Diaphragm is used for high pitched sounds

a) Lung sounds

b) Voice sounds

c) Murmurs

d) Rubs

e) Press down firmly so that when lifted, a ring appears on the patient’s skin

2. Bell is used for low pitched sounds

a) Heart sounds, s3, s4, gallops

b) Lightly lay the bell on the skin for contact but do not push down.

c) Bruits

D. How/Where to Listen

1. Anterior chest: mid clavicular, 1” below collarbone

a) Have the patient breath a little deeper than normal through their MOUTH

b) Listen to both sides and compare

c) Rhonchi, stridor best heard here

2. Laterally: 5^th intercostal space, mid clavicular

a) Wheezes heard and differentiated

3. Posterior bases: back below shoulder blades

a) Best place to hear crackles

E. Infants/small children

1. Smaller surface area means it is easy to transfer sounds across midline especially with an adult sized scope

2. Listen mid clavicular line just under arm pits

IV. Adventitious Lung Sounds

A. Normal bronchovesicular sounds

1. Sounds normally heard as air goes through large and smaller airways

B. Stridor

1. High pitched musical sound heard on inhalation and sometimes exhalation

2. Suggestive of upper airway obstruction

C. Rhonchi

1. Course rattling sound heard early on exhalation or inhalation

2. Caused as air passes through mucous

3. “Congestion” sounds heard in bronchitis

D. Wheezes

1. Musical sound heard as air passes through narrowed airway

2. Commonly associated with bronchospasmic diseases such as asthma, COPD, and anaphylaxis

a) Expiratory wheezes develop first

b) Inspiratory wheezes make it worse

c) Silent chest is pre-terminal – no air exchanged

E. Crackles (Rales)

1. Fine or course bubbling or “crackling” sound heard first and best in the posterior bases.

2. Heard as a result of air passing through liquid in alveoli i.e. pulmonary edema, fibrosis, or exudates in Pneumonia, or in ARDS.

3. Usually heard at the peak of inhalation, just before exhalation begins.

F. Pleural Friction Rub

1. Sounds painful, is painful, as in Pleurisy

2. Sounds like pieces of wet leather rubbing together

3. Heard best where the patient points out his/her pain.

V. Heart Sounds (basic)

A. Where to Listen: (see diagram page 10)

1. Normal S1 and S2

a) lub dub, lub-dub

b) S1 made as AV valves close

(1) Heard over 5th I/C space left sternal border an 5^th IC space mid clavicular

c) S2 heard as aortic/pulmonic valves close

(1) Heard over the 2^nd I/C space right and left sternal border

d) S3: third heart sound

(1) Heard with the BELL only over left sternal border

(2) Sound caused by abrupt deceleration of blood in a failing heart (Election fraction < 50), (vibrations)

(3) Occurs after S1-S2 (Lub-dub-dee, TENN-a-see, S3)

(4) Suggests heart failure in adults

2. S4: fourth heart sound

a) Heard with the BELL only

b) Sound caused by forceful contraction of the atria against high pressure and non-compliance of the left ventricle wall

c) Occurs BEFORE S1 (Dee Lub-dub “Ken-TUCK- Ey”, S4

d) Suggests heart failure and/or hypertrophy

3. Summation Gallup

a) Heard with the BELL and is a combination of S3 and S4

b) Suggest acute heart failure

4. Murmur

a) Heard with diaphragm over 5^th I/C space mid clavicular, “graded” based on intensity of the sound heard.

b) Murmurs are “whooshing” sound heard in conjunction with S2 or S1

c) Can indicate valve problems, need further tests, can also be innocent.

5. Pericardial Friction Rub

a) Heard with the diaphragm over ERB’s point or the left lower sternal border

b) Characteristic rubbing sound with crescendo heard constantly

c) Indicates pericarditis or other inflammatory process

VI. Voice Sounds

A. Purpose

1. In patients with diminished breath sounds, voice sounds can aid in determining consolidation (pus or liquid filled) versus air filled areas

2. Based on the fact that sound waves travel better through consolidated tissue rather than air.

B. Bronchophony

1. Done by placing stethoscope over the anterior upper lobes

2. Have the patient say 1,2,3, in a normal voice over and over

3. Distinct voice sounds indicate consolidation

4. Unintelligible voice sounds indicate air

C. Egophony

1. Place stethoscope over area of diminished breath sounds

2. Have the patient say “eeeeeeeeeeee”

3. “e” will sound like “a” in an area of consolidation

D. Whispered Pectoriloquy