What is the Stethoscope
For?
Stethoscopes are used to hear sounds generated from within
the body. They are used to listen to the heart, lungs
and intestinal tract. They are also used for measuring
blood pressure.
Basic Terminology
Bell
The bell of the stethoscope is the cup shaped part at
the end of the tubing, usually opposite to the diaphragm.
Not all stethoscopes have a bell. The bell is used to
listen to low pitch sounds.
Diaphragm
The diaphragm of the stethoscope is the flat part at the
end of the tubing, with the thin plastic "drum-like"
covering. The diaphragm is used to listen to high pitch
sounds. Some stethoscopes have a diaphragm but no bell.
Tubing
The stethoscope tubing transmits sound from the bell or
diaphragm to the earpieces. Some stethoscopes have single
tubes, some have double tubes. Double tubes are more sensitive,
but may rub against one another causing "squeaks"
to be heard.
Earpieces
Earpieces fit into the ears. They should angle slightly
forward for the best fit. Earpieces made of soft rubber
are more comfortable and may prevent outside sounds from
interfering with your listening.
What Do You Listen For?
Heart
The heart is located on the left side of the chest, between
the 4th and 6th ribs, almost directly under the breast.
Use the stethoscope to listen to your heart. Move it around
and notice if it sounds any different in different places.
Compare the sounds heard using the bell versus the diaphragm.
Normal heart sounds are "lub-dub". Each "lub-dub"
represents one contraction of the heart. The noises are
made when the valves snap shut. "Lub" is the
closing of the atrioventricular valves; "dub"
is the closing of the pulmonic and aortic valves (look
'em up in an anatomy book!)
Some people may have other heart sounds as well. If a
quiet "whoosh" is heard after the "lub-dub",
this is called a "murmur". Murmurs are the sounds
of the blood itself moving through the heart. It makes
noise when the blood flow has turbulence. This can be
because a valve doesn't open or close all the way. Many
people have heart murmurs without it affecting them at
all. If someone in the class has a murmur, ask if you
can listen and compare to your own heart's sounds.
Lungs and Airways
Listen to your lungs by placing the stethoscope over your
chest and breathing in and out deeply and slowly. Move
the stethoscope around and compare the noises heard in
different areas. Compare the sounds heard using the bell
versus the diaphragm. Normal lung sounds should not have
any crackles or wheezes in them. Place the stethoscope
over your throat and listen to the sounds your trachea
makes.
Percussion may be performed on the chest as well. Instead
of listening for sounds made by the body, you are listening
for sound reflected by sounds you make. For this exercise
you need a partner. Place the stethoscope on your partners
chest and lightly "thump" a finger against their
chest all around the stethoscope. Normal sounding lungs
sound slightly "hollow" because they have air
in them. Compare this to holding the stethoscope over
something solid like a shoulder blade. This sounds "dead".
If a lung sounds dead on percussion, it can indicate that
the lung has solidified, usually because of pneumonia.
Abnormal lung sounds include crackles and wheezes. If
the lung rubs on the chest wall there may be friction
rubs. Crackles sound just like the word sounds. They indicate
that there is fluid in the lungs, such as happens with
pneumonia or pulmonary edema. Wheezes are high pitched
whistling noises, and are heard with some pneumonias and
with airway diseases like bronchitis. Friction rubs are
squeaky sounds that can be heard with pleuritis (an infection
between the lung and the chest wall).
To mimic these sounds, create a model of the lung. Take
a balloon and stretch the open end over one end of the
tube. Take a sponge and shred it into small pieces. Push
the pieces through the tube into the balloon, until the
balloon is slightly stretched. Add enough water to moisten
the sponge. Squeeze out any excess. Now hold the stethoscope
to the balloon and blow in and out on one end of the tube
to slightly inflate the balloon. The slight crackly noise
you hear is similar to the crackles heard in patients
with pneumonia. Wheezes can be simulated by pinching on
the neck of the balloon, where it meets the tubing while
blowing in and out. Friction rubs can be created by rubbing
on the side of the balloon to make it squeak.
Abdomen
The abdomen can be listened to much like the chest. Holding
the stethoscope over the upper left part of the abdomen,
just under the ribs, you can hear the stomach gurgling.
In the lower part of the abdomen you can hear the intestines.
These noises are called "borborygmus". Borborygmus
is normal. However, a doctor will listen to these noises
and compare them with what is "normal" to decide
if your intestinal tract is overactive or underactive.
Percussion can also be used to listen to the abdomen.
Thumping over the upper right of the abdomen should sound
"dead" as a solid organ, the liver, is below
it. The stomach or lower abdomen may sound hollow if there
is gas in the intestinal tract.
Using a stethoscope is an age-old art in medicine and
is a very useful, non-invasive diagnostic tool to help
localize problems. This is important to allow the doctor
to determine what further tests are needed to diagnose
disease.
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