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It has become the defacto symbol for doctors, nurses, and other medical professionals. The basics of using the tool are simple: put it in your ears, then place one end on the patient, and listen.
Although this may seem easy at first glance, there is much more that can be done with a stethoscope. Utilizing a stethoscope for auscultation can be tricky, especially if you are new to the process. Fortunately, this article will provide a guide for the process, and help you learn the necessary skills.
In this article, we will review the basics of using a stethoscope, along with some facts about its capabilities.
In 1816, René Laennec invented the stethoscope. Laennec described the stethoscope as an “ear tube,” which is thought to have originated at Necker-Enfants Malades Hospital in Paris, France.
There have been a few changes over the next two centuries which you can read about in our article HERE.
The most modern model that everyone uses is currently credited to Harvard University’s Dr. David Littmann. His many advances succeeded in making the stethoscope both lighter, and acoustically superior.
To auscultate is to listen to the sounds of internal organs. This typically refers to using an instrument: in this case, a stethoscope.
Auscultation is done by both physician and nurse practitioner. The most important organs to auscultate are the carotid arteries and jugular veins, heart, lung fields (both right and left), liver, and abdominal organs.
Auscultation is important to determine what is going on inside the body at a given time or place. It can detect heart murmurs, abnormal sounds, and breathing changes in the lungs.
Parts of the Stethoscope
Modern stethoscopes (excluding digital stethoscopes and electronic stethoscopes) are relatively simple.
The following diagram will provide you with the important vocabulary, illustrating the stethoscope anatomy:
- The stethoscope diaphragm is the large, flattened side.
- The stethoscope bell is the side with the concave piece with a hole.
- Together, they are referred to as the chest piece.
Those two stethoscope parts are the most important components to understand.
The other parts include:
- Ear Tips
How the Stethoscope Works
The stethoscope diaphragm vibrates in a very similar way to your own eardrums. They are sealed membranes that vibrate in response to stimuli.
This disturbance of the diaphragm causes makes the air inside the stethoscope tube move, vibrating in response to the diaphragm. This makes hearing the sounds possible by transmitting air pressure changes along the tubes and into your ear canal.
The diaphragm helps to amplify sound by having a larger surface area than the tube. The air moving in the tube must travel farther than the diaphragm, causing a magnified signal to come out of the ear tip.
The larger the pressure waves in your ear, the louder the sound. It is in this way that stethoscopes amplify sound.
How to wear a Stethoscope
Turn the ear tips slightly so they point toward your nose after they have been placed in your ears. When you do it correctly, the seal will be strong.
You can adjust both the ear tip and tubing of a stethoscope to make it fit snuggly in your ears. It is recommended that you measure how long you want the tube, based on your height, and trim the length as necessary to achieve the perfect fit.
Holding a Stethoscope Correctly
As a rule of thumb, in most cases, you should hold the chest piece between your middle and index fingers on your dominant hand. In this way, you can press against the diaphragm/bell without making extra noise, as opposed to using your fingertips around the edge. The best way to handle something is with a gentle touch.
Here are some examples:
Hold the chest piece like this – by placing your thumb under the tube, you avoid rubbing it against the skin and causing extra noise.
Avoid holding it like this – the pinch grip makes it harder to control.
Placing the Stethoscope on the patient
To improve sound transmission, place the chest piece directly against the skin. Merely placing on the surface, auscultating through one layer of clothing, such as a T-shirt, can be tempting if you’re in a hurry. But doing so can mean losing subtleties that may be very important.
Auscultation and What You Can Do With It
If you were to learn and apply all of the following stethoscope skills, then you would be more thorough than 90% of clinicians out there. You’ll find free information on the technique by clicking on the links.
The most common application, but often misunderstood or handled poorly.
Taking blood pressure with a blood pressure cuff requires perfect placement.
It is frequently taught that the diastolic blood pressure (e.g. 120/80) occurs when it reaches a point where no longer can the thump of the brachial artery be heard.
More accurately, diastolic pressure represents the point at which the volume of the thump reduces dramatically. This is often an increase of 4-10 mm Hg above when the sound disappeared completely.
This test helps you determine the rate, rhythm, and quality of breathing, as well as listen for obstructions of the airways and indicators for inflammation of the pleura.
You should also try to expose the triangle of auscultation when listening to the back of the patient. Start above the clavicle; lung tissue extends high from this point. See the pink area in the picture below:
Listen to the lung sounds in the auscultation triangle; six pairs of points on the chest, and seven pairs of points on the back.
You can remember this using the mnemonic “6 AM – 7 PM,” (6 anterior points, and 7 posterior points).
Whenever possible, listen to both left and right sides one after the other before moving down – this way, you can notice any distinct differences immediately.
With a stethoscope, we listen to the rate and rhythm of the heart as well as sounds that shouldn’t be there (such as gallops, murmurs, or clicks). These are known as adventitious sounds.
It is a common experience for students – at first, all hearts sound the same. But after gaining experience, listening to many hearts, the adventitious sounds will suddenly become quite noticeable.
To auscultate heart sounds, we listen to four primary points:
- Left of the sternum at the level of the 2nd rib
- Right of the sternum at the level of the 2nd rib
- Left of the sternum at the 4th rib
- On the left nipple line at the level of the 5th rib
You can use the mnemonic “2-2-4-5” to help remember this method.
The names of the valves that you are hearing in these locations are:
- (2 right) aortic
- (2 left) pulmonic
- (4) tricuspid
- (5) mitral
You can remember these with the mnemonic “All Patients Take Meds” or “Apartment M2245.”
APE TO MAN
APE TO MAN is another useful mnemonic for remembering the pattern of heart auscultation.
These letters refer to various points of listening to your heart. Those are not based on the precise anatomical locations of the valves.
Ape to Man Heart Auscultation:
- A- Aortic Valve (right of the sternal border in 2nd intercostal space)
- P-Pulmonic Valve (left of the sternal border in 2nd intercostal space)
- E-Erbs Point (left of the sternal border in 3rd intercostal space)
- T(o)- Tricuspid Valve (left of the sternal border in 4th intercostal space)
- M(an)-Mitral Valve (left of sternum along mid-clavicular line in 5th intercostal space)
Working from the aortic valve to the mitral valve is the best way to approach it. As you proceed, listening to the various sounds of the valve in each area.
4. Auscultation bowel sounds
This can be an important test if you believe that you are dealing with a paralytic ileus or a bowel obstruction.
Fun fact: “Borborygmi” are the gurgling or bubbling noises that are produced in the bowels.
5. Finding bruits
A bruit (pronounced “broo-ee”) is an abnormal “whoosh” noise heard during auscultation, caused by blood flowing through a narrowed artery. Thus, as in arteriosclerosis.
There should be no bruits in an asymptomatic patient. If the patient is in good health, you should not hear any bruits.
You can detect bruits in the neck (carotid bruits), femoral, umbilicus (abdominal aortic bruits), iliac, kidneys (renal bruits), and temporal arteries.
When I first heard a true bruit in an abdomen, it was above the belly button just above the umbilical artery, and I knew instantly that the patient had an abdominal aortic aneurysm (AAA).
It was an exciting discovery for me, and it potentially saved the life of my patient.
6. Assessing the size of the liver
It is commonly done by percussion (tapping the belly), but there is another neat technique you can use.
Just above the beltline, place the index finger on the right nipple, and gently drag your fingernail up the skin toward the chest piece of the stethoscope.
You will hear a duller sound over the liver when you are over the liver.
A good method of measuring the size of the liver in that region is to mark the start and end of dullness. The nipple line should be about 10 cm apart.
7. Makeshift Hearing Aid
In addition, the stethoscope can also be used as a hearing aid for people with hearing impairments.
Talk into the chest piece while the ear tips are in the patient’s ears, to amplify your own voice and questions to the patient.
This can be especially useful in an emergency room situation!
Using the Diaphragm vs. the Bell
High-pitched sounds, such as breathing and normal heartbeat, should be auscultated via the diaphragm.
Bells are most effective at detecting lower frequency sounds, such as heart murmurs and bowel sounds. When performing a cardiac exam, you should use it to detect dull-sounding heartbeats and to detect bruits (for the diaphragm, then the bell).
When using the bell, hold it gently against the patient’s skin to auscultate lower sounds. You can press it more firmly to auscultate higher sounds.
Which Stethoscope Should I Buy?
We at Stethoscopes Ninja have curated many guides suited to helping you choose the Stethoscope that will work the best for your needs, in your current stage of practice.
If you are still a med student, check out our guide to the top 10 affordable stethoscopes for students!
In the cardiology field, the 3M Littmann Master Cardiology is generally accepted as the gold standard. The 3M Littmann brand itself is a hallmark of quality and prestige.
You can also check out our guide through the many available Littmann models here: Littmann Stethoscope reviews
Some may not be interested in the higher price tags, and many in fact prefer the underdog models: MDF Stethoscope Reviews
We also have a definitive guide to stethoscopes, to help you choose from the best of many!
Finally, the last guide that we will plug: the digital revolution is here, and we review the most popular electronic and digital stethoscopes.
Stethoscope Hygeeine – Controlling Infection
Keep your stethoscope clean regularly, especially the chest piece.
The stethoscope is the most common vehicle for transmitting diseases from patient to patient.
An alcohol wipe or some hydrogen peroxide is all that is needed to disinfect the chest piece.
If you’d like to read more on this topic of stethoscope contamination, check out our article on stethoscope contamination and covid-19.
The stethoscope is an often underappreciated medical device and a vital part of any healthcare provider’s armamentarium.
It should be kept clean and maintained well to ensure its function, as well as a patient’s safety.
But most importantly, the skills and technique of auscultation must be practiced to master them. So practice a lot!
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