Parts of a Stethoscope

All medical professionals use a stethoscope every day. A stethoscope is the most essential tool in a doctor’s kit. As a healthcare provider, you will use a stethoscope so often until you feel like it is a part of you. However, you should know how it functions.

It is likely that you have never thought about the parts of a stethoscope, how they work or how they were made. If you know and understand more about stethoscopes, you can make better decisions when purchasing them, using them and caring for them.

Let’s go through an overview of the parts of a stethoscope.

Major Parts of a Stethoscope

1. Chest piece – This is the logical part to begin with since “stethos” means chest .The chest piece is the part held against the patient’s body.
2. The Stem – This is the part that connects the chest piece and the tubing.
3. Diaphragm – This part can either be double-sided or single-sided.

– A double-sided chest piece normally has a diaphragm on one side and a bell which is deep cup-shaped.

– Both the double-sided and single-sided chest pieces are surrounded by a flexible ring known as a chill ring. The ring helps to create an airtight seal as well as buffer the patient against any coldness.

4. Headset – This is the metal part of the stethoscope.
5. Acoustic tubes – These are hollow rubber-like tubes that link the ear tubes to the chest piece.
6. Earpiece – This is the small tip at the ends of the ear tube that is placed in the ears. Some stethoscopes either have soft silicone or hard plastic earpieces.
7. Ear tubes – These are the hollow metallic tubes that are connected to the ear pieces on one end and the acoustic tubes on the other end.

The following diagram shows the parts of a stethoscope.

What is Used to Make Stethoscope Parts?

Although different manufacturers may use slightly different materials to make their stethoscopes, there are some common ones used during manufacture. These include:

Metals

The ear tubes and chest piece are commonly made of metal. These parts are often made of Stainless Steel or aluminum. However, the chest piece can also be made using zinc or titanium while the ear tubes can be made of brass.

The aluminum parts are created through a process known as die-casting. This is when molten aluminum is poured into a mold to be transformed into a specific shape. The cooled casting is then taken out of the mold and worked on by a machine into its refined final shape.

Stainless Steel cannot be molded using the die-casting method because the metal arrives at the manufacturing plant when it has already been formed into rods. The rods are later shaped on a lathe which cuts away excess metal, leaving them in their desired final shapes.

Brass ear tubes are usually not made of solid brass. Instead, they have an outer coating made of brass that has been electroplated onto a base metal. Stethoscope manufacturers normally machine the tubes and then outsource the electroplating.

Non Metals

Every soft part of the stethoscope was traditionally made of rubber. However, thanks to modern technology, they can now be made of silicone, plastic or PVC. Earpieces are often made of hard plastic or silicone. They pieces first molded to the desired size and the shapes are estimated to fit into the ear canal.

There are two distinct methods used to form the tubes. Each method is reflected in the price of the stethoscope. The affordable method is to extrude or mold the tubes, allowing them to be manufactured in only one step. The expensive method is done by repeatedly dipping the tubes so that thin layers of material can build up to the desired level of thickness.

How a Stethoscope is Assembled

You might find this surprising, but stethoscopes are assembled by hand. The first step is to screw together the ear tubes and the acoustic tubes. The manufacturing process creates a barb on each end of the ear tubes. Gently heating the ends of the acoustic tubes makes it possible to slip them over the barbs with ease, which in turn holds them into place.

The earpieces will then be threaded onto the opposite end of the ear tubes. The diaphragm is screwed into the chest piece while the chill ring is tied around the chest piece. To finish the assembling, the acoustic tube is attached to the chest piece. With this done, you have a complete stethoscope.

The instrument is then tested and inspected before it is shipped to the market.

How a Stethoscope Works

“Stethos” means chest while “scope” means to hear. The meaning is clear but how exactly does a stethoscope work when it is used to examine the lungs, chest or abdomen? Each part of the stethoscope and its features are designed with a particular function in mind.

Stethoscopes work using sound waves. In other words, a stethoscope is used to transmit sound waves from a patient’s body to the doctor’s ears. The body makes sounds while it goes about doing its business. You are able to hear the heart beating and also valves opening and closing. If your lungs are healthy they will sound hollow and if they are diseased they may crackle or wheeze.

The sounds produced or absence of sound from the abdomen is a way of giving you vital clues of what’s going on in the gut. The sounds can either be low-frequency or high-frequency. Low-frequency sounds will only make it to as far as the skin. On the other hand, high frequency sounds are loud enough to vibrate the diaphragm (part of the chest piece) of the stethoscope while it is held against the body.

When you lightly press the chest piece against the skin, you’ll be able to pick up low-frequency sounds. If you press it more firmly, you’ll be able to get high-frequency waves. From the chest piece, sound waves will travel up to the acoustic tubes. The waves will then bounce off the sides of the tubes and will later be reflected up in the ear tubes and finally on the earpieces. This is why the earpieces should fit snugly and the tubes have to be airtight.

Cleaning and Maintaining a Stethoscope

A stethoscope is a hardworking instrument. Although it rarely complains, there are a number of things you ought to do in order to keep it happy and healthy.

• Occasionally inspect your stethoscope to confirm that there are no obvious damages like cracked earpieces or punctured tubes.
• Wipe the chest piece and earpieces frequently using 70 % isopropyl alcohol to disinfect and clean them. The tubes can be cleaned using either soapy water or 70 % isopropyl alcohol.
• If you normally wear your stethoscope draped around the neck, always keep it around the collar. This is to avoid making the tubing stiff when continuously exposed to the skin.
• Avoid exposing your stethoscope to extreme temperatures (hot and cold), oils or solvents because they could easily degrade the materials.
• Don’t throw away the stethoscope’s manual as it will come in handy for the care and maintenance of the instrument.

If you go by the prescribed rules, you will end up using your stethoscope for many years. Make sure to store, clean and use the stethoscope as required. A good quality stethoscope is an investment. Choose one that will meet your needs and expectations.