In many branches of medicine, a reliable stethoscope is one of the most fundamental pieces of equipment. As with any product, making a choice to invest can be a minefield. There are many different varieties of stethoscope. Different people have different needs. It can all become very confusing.
It would be too easy to simply post a few links to various stethoscopes and say, “Choose the best one for you.” Knowledge is power, though. You need to be fully informed about what this vital piece of kit does, the different types available, what things to focus on before making a purchase and to be absolutely clear about your precise requirements. So, before anything else, first thing’s first…
What is a stethoscope?
A stethoscope is perhaps the piece of kit we most readily associate with the medical profession. Doctors, nurses, students, ER workers, vets… anywhere that medicine is practiced, a stethoscope will not be far away. Technology continues to transform our experience of modern medicine. The stethoscope, though, still plays a pivotal part in the diagnosis of vascular, lung and heart conditions.
In the simplest sense, you put one end in your ear, the other against the patient, listen and then diagnose. Listening for sounds in this way is known as auscultation. The major uses for a stethoscope are listening to the heart, lungs and the intestinal tract.
Whether it’s used to externally evaluate a range of symptoms or for internal auscultation, the stethoscope has truly redefined diagnostics. It has helped the medical profession to take a proper, in-depth look at internal anatomy without needing to resort to the invasive methods previously employed. They are safe, easy to use and highly accurate.
There’s much more to stethoscopes than that.
The word itself comes from two Greek root words, stethos (chest) and scopos (examination).
The very first stethoscopes came into being in 1816. René Laennec at the French Necker-Enfants Maladies Hospital was responsible for inventing them. These early prototypes were little more than crude listening tubes. The tube of this primitive ear trumpet was made from wood.
There were some minor changes made in the years to follow. Binaural stethoscopes were made – they allow the user to listen with both ears – and the tubing was made much more flexible.
Stethoscopes were first produced commercially in 1852. George Cammann was behind the tweaks which made it practical to mass-produce this vital piece of equipment.
Dr David Littman of Harvard University was a major contributor to more radical advances in design. The stethoscopes we know today are based on the important changes which he brought about. Principally, he made the stethoscope much lighter and worked on enhancing the acoustics.
How Does a Stethoscope Work?
In the simplest sense, a stethoscope amplifies the sounds in the body. These sounds are transmitted to the ear.
Most models come equipped with a chest piece which is generally round and flat. A thin plastic skin acts as a cover. This plastic, tightly stretched over the chest piece, is called a diaphragm. Sound causes the diaphragm to vibrate. The sounds emitted are extremely high frequency. These sounds enter the earpieces (made from hollow metal) via the hollow tubing made of plastic.
Because the diaphragm is a sealed membrane, it functions in a similar way to the human eardrum. As it vibrates, the air inside the tubing moves up and down. As a result of this movement, the air is pushed in and out of the listener’s ear canal.
The diaphragm has a much larger area than the column of air which is moving. This means that the air inside the tube has to travel a greater distance than the diaphragm. The pressure waves are thus magnified which leads to louder sounds in the ear. This is the very basic science behind the way in which stethoscopes amplify sound.
In a healthy adult heart, there are two distinct sounds.
The first part of the beat is known as a lub. When the tricuspid and mitral valves close at the same time, this sound is created. These valves are found between the heart’s lower and upper chambers.
The second dub sound happens when blood exits the heart. It travels through the pulmonary arteries and the aorta. As the valves to these arteries close simultaneously, the dub sound is produced.
The Parts of a Stethoscope
Stethoscopes vary in design and function. Most stethoscopes are constructed from rubber tubing fashioned in a Y-shape. This is so that the sounds can travel in the most efficient manner. The devices to detect sound are often two-sided but many newer models come with a single head which is highly sensitive to pressure.
Binaural stethoscopes are designed to be used with both ears while single stethoscopes are made for one.
With certain models, they must be places in direct contact with the skin. Others function perfectly well through clothing. Here is a rundown of the basic elements you should be aware of as they will affect your purchasing decision…
- Tube: Clearly, the tubing is critical. The material will influence how long the tubing lasts and also its performance. Double lining can reduce the noise kicked out due to friction.
- Bell and diaphragm: Again, chestpieces differ. The bell is small, concave and has a hole in the center. The diaphragm is bigger and flat. Some have a diaphragm on one side and a bell on the other. The bell is useful for picking up different frequencies. Two-sided diaphragms are often used for children and smaller patients. Consider your specific needs which we will examine in more detail later.
- Earpieces: Soft, hard or gel? Each of these comes with advantages and drawbacks so the best thing is to try them and see which feel best. Think about your requirements. These earpieces are almost always changeable. With the more expensive versions you are likely to have more than one kind provided so you can swap them as necessary.
- Weight: The chestpiece accounts for most of the weight. The heavier it is, the higher quality the sound. Think, though: if it’s too heavy for you then prolonged use hanging around the neck can cause discomfort and even neck pain.
What Can You Do With A Stethoscope?
We are going to look here at 7 specific uses for your stethoscope. The more you know about this piece of equipment, the more you can put it to work for you.
- Measuring the blood pressure: This is perhaps the most standard way in which the stethoscope is used. It is also often conducted very poorly. Where you place the BP cuff is critical. This handy guide makes that very clear. Do not be confused, either, about the diastolic BP. With the numbers 120/80, the second number represents this. Some are wrongly taught that this is the stage at which thumping of the brachial artery is no longer heard. It’s actually when the noise level of the thump sharply dips.
- Measuring the liver’s span: One way to do this is by tapping the belly. This is known as percussion. Another approach is to put the stethoscope under the right nipple, line up your index finger with this just above the line of the belt then scratch upwards gently towards the stethoscope’s chestpiece. The sound becomes duller as you go over the liver. If you are able to mark this location – note where the dullness starts and finishes – you can pretty accurately measure the size of the organ. 10cm is considered a normal liver span.
- Assessment of heart sounds: As with the lungs, primarily you will listen for rhythm, rate and quality. Clicks, murmurs or gallops are called adventitious sounds and this means that they should not be there. Monitoring these is important. When listening for heart sounds, four main areas are concentrated on. You will hear the sounds from different valves in different locations (mitral, tricuspid, pulmonic and aortic).
- Assessment of bowel sounds: If a bowel obstruction is suspected, the stethoscope can be used to easily detect any unusual sounds and from there to diagnose the problem and offer treatment accordingly.
- Discovering bruits: This comes from the French word meaning noises. The unwanted sound of blood whistling through an artery normally points towards that artery being narrowed. This is what causes such abnormal and turbulent blood flow. In normal and healthy patients there should be no bruits. These bruits, when detected, can be present in the abdomen, neck, kidneys as well as in the temporal, iliac and femoral arteries. Locating bruits can literally save a patient’s life as they can show serious complaints such as arteriosclerosis or aneurysms.
- Hearing aid: If you encounter a patient who has problems hearing then the stethoscope is a highly adaptable tool… Offer the patient the ear tips and speak into the chestpiece. Problem solved!
The Different Types of Stethoscope
There is an extremely wide range of stethoscope varieties. In order to understand which work best for different fields of medicine, it’s necessary to take a look at what this categories are…
- Electronic: The amplification of sound is superb with an electronic stethoscope. Filtering is possible. This means kissing goodbye to the annoying interference from ambient sound which can make diagnosis awkward and problematic.
- Digital: In today’s wired world, we are all used to digital technology. One of the key advantages of this advanced type of stethoscope is their diagnostic ability. It’s possible to save the sounds that you hear. These sounds can then be compared both before and after surgery.
- Doppler: Doppler stethoscopes are perfect for pregnant women. They are a superb way of listening for the heartbeat of a baby.
- Infant: Not all stethoscopes are equal. Trying to use one designed for an adult on a small child is a recipe for disaster. In the best scenario it will not work well, perhaps not at all. An infant stethoscope is made with an extremely small head. If you try to use a head fashioned for adults you will experience distortion and a lot of background noise will be picked up. The specially small chestpiece will also help to reduce ambient noise and the result is an accurate, high-quality sound.
- Pediatric: This operates on the same principle as an infant stethoscope but is very slightly bigger. You wouldn’t expect to dress a baby and a child in the same clothes; a stethoscope is no different. The size of the chestpiece, again, will be perfectly suited to children.
- Fetal: As the name suggests, this type of stethoscope is designed so that you can hear the heartbeat of a fetus. These are used by healthcare professionals and expecting parents. The Pincard is an example of a very simply designed tool which is in common usage for this purpose.
- Neonatal: This is another term which you might see for a stethoscope fashioned to listen to the lungs of newborns.
- Amplified/hearing impaired: Just because you have a hearing problem it does not mean you cannot work in the field of medicine. Often, being exposed to the wailing sirens present in the workplace can bring about hearing issues. Focus on one of these specialist stethoscopes if you need something with extra amplification.
- Lightweight: For those who want to avoid the need to use a heating pad after wearing a heavy stethoscope around their neck all day, it’s wise to look for one of the many extremely lightweight offerings. This can make neck pain a thing of the past.
- Cardiac: If you will be mainly listening for heart murmurs then you need some specialist kit. Cardiology stethoscopes will give the most accurate results.
- Veterinary: Just as children and adults are different, so are animals. If you work as a vet then you need dedicated equipment. It’s important to pay attention to the size of the animals you work with most. If you are mainly treating horses then a stethoscope designed with small birds in mind is not the best tool for the job.
What Is Your Intended Use?
As outlined in the above section, there is a truly staggering range of stethoscopes available on the market. Different specialties each have their own demands. For an entry-level nurse, there is no need to break the bank and buy a high-end model. A cardiologist, though, needs to focus on quality above all else. Think very carefully about your own particular requirements. Here are some handy pointers…
Stethoscope for EMT ( Emergency medical technician)
Paramedics and those working in EMT operate in hostile, harsh environments. When considering such conditions, durability is equally as important as quality. Look for something well-made and built to last which will also deliver the best results. People’s lives depend on it!
Stethoscope for Doctors
For doctors, only the best is good enough. Money should not be an issue – even the most expensive models are not outrageously priced – so a known brand with a documented history and good reviews is essential.
Stethoscope for Nursing and Medical Students
While a doctor is likely to be very solvent, money is more of a factor for struggling students. Price should be uppermost in your decision-making but not at the expense of quality. This crucial instrument will help you to advance in your career so study the different options and go for a middle ground of something affordable which will still deliver accurate results. You can always go for an upgrade at a later stage.
Stethoscope for Nurses
If you are on your feet all day then weight is a flashpoint. Do not buy something too heavy which will only end up causing you problems after a long day walking around. Many lightweight options exist so consider this factor before making a purchase.
Stethoscope for Respiratory Therapists
If you work as an RT – or, indeed, a specialist pulmonologist – listening to the sounds made by the lungs is key. Make sure that you do not rush into buying a generic stethoscope which is not cut out for the exacting demands of this field.
What are some reliable stethoscope brands?
Not all stethoscopes are equal. In life you usually get what you pay for and, to generalize, known brands are normally recognized for a reason. Littmann is a manufacturer long held in very high regard. If you think not only of cost but also reputation, warranty, recommendations and aesthetics then you simply can’t go far wrong with a Littmann. Invest in one of these stethoscopes and you will enjoy high quality results for a long time to come. Other brands which rate a mention are Ultrascope, MDF and Welch-Allyn.
Where Should You Buy a Stethoscope?
As well as helping you with your initial research, the Internet is a wonderful place to make purchases too and it’s no different with stethoscopes. After fully researching exactly what you want from this piece of equipment, start comparing prices online. It’s essential that you are not driven purely by price. Check that the seller has a good reputation. Usually, if a website is not reputable there will be some complaints so steer of rogue vendors. Look also for the costs of shipping. You could begin with a good price but if the mailing costs are too high, any saving will be wiped out. The warranty should not be overlooked either. Examine the length of time for which you will be covered and look closely for any restrictions.
If you are not comfortable buying online then go to a bricks-and-mortar store. The advantage of making a physical purchase is that you will be able to talk to a knowledgeable salesperson and also try the various stethoscopes on for size, fit and weight.
Buying a stethoscope is not something you should rush into. Take your time reading in detail about what they do and bear in mind exactly what you want and need. Study reviews. These are usually impartial and honest. If the same positive or negative point is repeatedly raised in reviews then it is likely to be something worth considering.
The main considerations you should have in mind are quality, price and aesthetics.
As a general rule of thumb, if you spend less than $60 you are likely to end up with something of questionable build quality. They may start out working OK but they will not be as durable. They will also have a much weaker sound profile.
Although this article is not focused on specific reviews, the 3M Littmann Cardiology III is the industry standard benchmark against which other models are measured.
If you are listening chiefly for sounds with a higher pitch – breathing, normal heart sounds – then the diaphragm is best.
Bell versions are superior for lower pitch sounds. If you are investigating bowel sounds, heart murmurs, bruits and heart sounds in the most general sense, then the bell stethoscope is best suited to these tasks.
Remember: All stethoscopes, the chestpiece in particular, should be very regularly cleaned in order to control any infections. Diseases can be very easily transmitted if the equipment is not routinely disinfected. With the models that are used directly on bare skin this is paramount.
Cleaning, though, is a breeze… Simply wipe with an alcohol prep pad and the job’s done.
So… If you are looking to buy a stethoscope then check here for some reviews after researching fully exactly what you need.
Last updated 08/21/2016