Although Nurse Focus is mostly directed towards qualified nurses, I often get questions and comments from visitors that are interested in pursuing a career in nursing or may have found themselves administering home care for a loved one.
This means that I would like to start writing more content for those with less experience. To that end, today, we are going to look at the many uses of the good old stethoscope and how to use one at home.
If you are interested in buying a stethoscope, you should check out my article here.
Now, though, let’s take a quick look at how a stethoscope works.
How Stethoscopes Work
The principle behind how a stethoscope remains more or less unchanged from its origins well over a hundred years ago.
(There are digital stethoscopes available that connect to your cell phone now to record data etc, however, these still sell in far fewer numbers compared to traditional, analog stethoscopes.)
The part of the stethoscope that is pressed against the patient is called the diaphragm or bell. This is a sealed membrane used to pick up the sound being targeted.
These sound waves from the patient’s body are transferred to the air inside the stethoscope tube.
This long, narrow tube works to amplify these sounds as they travel up to the ear tips of the stethoscope.
These are of course placed inside the caregiver’s ear so that the sounds can be detected.
All in all, a very simple premise, which is a big reason that the design has not changed over the centuries.
How to Operate a Stethoscope at home
Because the instrument is relatively simple in design, operating a stethoscope is easy too. There’s not much you need to get to grips with.
Let’s take a look.
How to wear a stethoscope
Place the ear tips in the ear so that outside sounds are at a minimum. The tips should point forward slightly towards the nose.
How to hold the stethoscope
The correct way to hold the diaphragm or bell is between the index and middle fingers of your main hand.
To minimize and interfering noises, you should curl the thumb under the tube to keep it from moving.
If the tube brushes against you or the patient, it will cause annoying sounds that will mask what you are listening for.
Which side to use: bell or diaphragm?
The diaphragm is the larger side of the listening piece and is used to detect breathing and heart rhythms.
The smaller side of the listening piece is the bell and should be used to detect abnormal heart sounds and bruits. A bell is normally used to detect bowel sounds too, (see below for more on this).
A cardiac exam will often use both the bell and diaphragm.
The listening piece should be placed directly on the flesh, or at the very least against the item of clothing touching the skin.
What can a Stethoscope be used to detect?
Of course, detecting sounds is only useful if what is being heard can be analyzed to provide a consistent and reliable prognosis.
This comes with training, however, with experienced ears, the following issues can be measured and/or detected.
Measuring Blood pressure
I have explained before how stethoscopes can be used in conjunction with a sphygmomanometer to measure blood pressure. (Head here for an in-depth guide).
Essentially, the stethoscope is used to listen to audible heartbeats in the arm (the brachial artery) after the cuff of the sphygmomanometer has been inflated.
Systolic and diastolic pressures are read from the dial by detecting the points at which the Korotkoff sounds are first heard and when they disappear.
If this sounds confusing, make sure to check out my guide.
Listening to the heart
Heart “murmurs” and other irregularities of the heartbeat can also be detected with the stethoscope.
This definitely takes an experienced ear to hear, which is why it takes time to become a qualified nurse or doctor.
However, with a digital stethoscope that can compare sound readings to a database of sounds, such issues can be found by more inexperienced users of a stethoscope.
Either way, a standard heart checkup includes listening to the four main areas around the heart.
Detecting abnormal blood flow and vascular issues (bruits)
A stethoscope can be placed in areas of the body where the arterial flow can be detected and heard, in order to listen for Bruits.
These are very distinct, “whooshing” sounds of irregular and forced blood flow. Such sounds are an indication of vascular problems such as arteriosclerosis or aneurysms.
The biology of bruits is relatively simple to understand. If you think of your arteries as rivers, where the artery is tighter or narrower than it should be, it causes the blood to rush through under greater pressure.
Identifying abnormalities in the lungs
We’ve all been to the doctor with a raspy cold or flu and had them place the cold stethoscope diaphragm on our chest and back.
Anyway, in this scenario, the stethoscope is being used to identify any airway blockages or lung inflammation.
What you might not know, however, is that although the nurse or doctor can detect abnormalities, the reason various areas of the chest and back are measured is that they are comparing sounds within your own lungs.
Each lung, left and right is split into upper and lower lobes, and by completing a lung checkup via “paired areas” (i.e the same spots on either side), comparisons can be made.
In this way, it is much easier to hear if any issues and abnormalities are present.
Measuring the size of the liver
Believe it or not, you can even use a stethoscope to ascertain the size of a patient’s liver.
It is not an exact science of course, and a proper scan will always be advised, however, a simple test will help detect if any inflammation of the liver might have occurred.
It involves placing the stethoscope beneath the right nipple, with the index finger placed directly in the nipple line, and work upwards from the waist.
The stethoscope operator then has to gently palpate the skin as the stethoscope is moved upwards.
Essentially, the rubbing sound of palpation is much duller while the finger is over the area of the liver.
By marking the beginning and ending points of this dull sound, you have an approximate length of the liver. Anything around 10 cm is considered normal.
Identify bowel sounds
Finally, you can use a stethoscope to check for abnormal sounds in the bowel. This can be used to detect bowel obstructions or paralytic ileus.
Borborygmi sounds (i.e the normal gurgling of the bowels) will often be present, which again means it takes a trained ear to detect issues behind these.
- “Measuring blood pressure from Korotkoff sounds as the brachial cuff inflates on average provides higher values than when the cuff deflates“. Branko G Celler and Ahmadreza Argha, (September 2021), Institute of Physics and Engineering in Medicine. LINK
- “Physical Examination of Neck” Chen G., Zeng R. (2020) . In: Wan XH., Zeng R. (eds) Handbook of Clinical Diagnostics. Springer, Singapore. https://doi.org/10.1007/978-981-13-7677-1_44
- “Digital stethoscope: technology update” Supreeya Swarup and Amgad N Makaryus, Med Devices (Auckl). 2018; 11: 29–36. DOI: 10.2147/MDER.S135882