We gave some advice how to choose a stethoscope earlier. Now, let's talk about how to use it.

When I was a student at the medical university, I thought that stethoscope is a primitive and boring thing. Now, after twenty years of medical practice, I can say that stethoscope is an elegant tool with the long history of development. Stethoscope turns a doctor to a powerful diagnostic machine. Life and death of our patients sometimes depend on our ability to use our stethoscopes correctly. 

We gave some advice how to choose a stethoscope earlier. Now, let's talk about how to use it. 

At first, we must ensure sound's quality. Minimising external noise is important. The quieter our surrounding is the more sound details we will be able to appreciate. All the time I try to close all windows and switch off all machines: PC, cooler, ultrasound machine, air-conditioner, etc. If you fail struggling for silence, you may try a digital stethoscope with the noise reduction function. It can help if the noise is mild. 

When you are listening to a patient's heart, room,  your stethoscope and your hands must be warm. When cold, patient's  muscle can fasciculate producinga low-frequency noise, which competes with the heart sound. Even digital stethoscopes can't remove this noise. So, examination room must be warm. 

Next. The space inside the stethoscope between the skin, where the bell of the stethoscope is positioned, and doctor's eardrums has to be hermetically isolated. This means that the bell of the stethoscope must be pressed into the skin along its entire circumference. Furthermore, stethoscope’s earpieces must tightly close to your external auditory meatuses. Otherwise, volume of the heart sound obtained will be much lower.

Sometimes it is easier to press properly small bell than large diaphragm. 

Almost all existing stethoscopes have earpieces slightly turned outward, like this:

This is because our external auditory meatuses are slightly turned backwards. As a result, earpieces openings are in front of the eardrums. You can adjust to your desired angle. 

But remember: openings of earpieces can be applied directly against the walls of external auditory meatuses if the angle is wrong. This can deteriorate heart sound. This is likely to happen with the use of soft earpieces. So, choose correct angle. 

There are two kinds of people my friend.. oh, sorry. There are two kinds of heart sounds: low-frequency sounds and high frequency sounds. Sounds of gallop rhythms S3 and S4, for example, are low frequency. On the other hand, the murmur of aortic insufficiency is a high frequency sound. This is vital. Your stethoscope must allow listening for low and hight frequency sounds selectively. 

In conventional stethoscopes the bell is used for low sounds, and the membrane is used for hight frequency sounds. There is one important detail though. The tighter membrane is held against the skin, the larger fraction of low-frequency sounds is removed. When we press on the bell forcefully, skin under the bell is tightening and begins to function as a membrane. So, do not press on chest piece of your stethoscope when you are listening to the low-frequency sounds. 

There are some models of stethoscopes which only have membrane. This membrane is very special.  When chest piece of such stethoscope is applied lightly, we selectively hear low-frequency sounds. When it is applied firmly, we selectively hear high frequency sounds. This helps to save time. Chest piece of such stethoscope is flat and can be easily placed under manometer cuff. 

Digital stethoscopes give opportunity to selectively listen to low and high frequency sounds as well. Appropriate acoustic mode can be selected with the help of a button. 

Do not think, that stethoscope’s bell firmly applied to the skin, works as good, as a membrane. No. It does not. Membrane is still better adopted for high frequency sounds auscultation. 

Avoid carrying your stethoscope on your neck. It will lead to premature wear of stethoscope’s flexible tubing. Do not do that.

Clean chest piece of your stethoscope with antiseptic solution according to manufacturer’s instruction. 

We have five points of heart auscultation on human chest. How to use stethoscope at each point? Should we use the diaphragm and the bell on every point? In what position patient should be when we perform auscultation and what is the best order? You will find all the answers in our next publications.