Why Does a Stethoscope Feel Cold?

Why Does a Stethoscope Feel Cold main

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We all have a memory of shivering after the doctor applied a cold stethoscope chestpiece on our chest. So what is puzzling is that even in the summer, stethoscopes still feel cold. But why is that? And are there ways to warm up a stethoscope? It is the question that we will aim to answer in this article.

Why do the diaphragms of stethoscopes feel cold?

The answer is simple and resides because stethoscopes, diaphragms, and bells are made of metal to transmit sounds efficiently. In theory, metals are very heat conductors meaning that the stethoscope head should be the same temperature as the room. And it is! Nevertheless, you feel the cold.

Why? Because of the thermodynamics principles. Do you have a metal cup or a metal object nearby? I suggest that you grab it. Did you feel the cold transient sensation?

When you pour hot water into cold water, you will have lukewarm water. It means that the heat from the hot water will be transferred to the cold water. The same principle applies to a metal-made stethoscope head and the skin. The heat from the warm skin will be attracted by the cold diaphragm ring and will induce a transient feeling of coldness.

Let’s explain what I mean. The temperature of the metal stethoscope is room temperature. However, metal is an excellent conductor of heat, so it removes heat from your body, which is at a temperature higher than the surrounding environment, more quickly than it would if it were built from a less conductive substance.

So what is the trick not to feeling cold? The answer is simple. It would help if you increased the temperature of the stethoscope head to a level higher than the skin temperature.

Let’s be more specific. The average skin temperature is around 33 degrees Celsius or 92 degrees Fahrenheit. In comparison, an average room temperature that corresponds to the temperature of the stethoscope will be the 20 degrees Celsius (68 degrees Fahrenheit) range. 

When in contact with the skin, the metal of the stethoscope will absorb the extra heat from the skin to reach a lukewarm average. This is why you feel the cold when a stethoscope is applied to the skin.

How to reduce the cold feeling when a stethoscope is applied?

Now that you understand why a stethoscope feels cold, you certainly have an idea of how to reduce this uncomfortable feeling?

The answer is to increase the temperature of the stethoscope head for the temperature difference between the skin and the metal to be reduced. In theory, you would like the stethoscope’s metal to be at the same temperature as the skin.

That is why some considerate doctors will hold the chest piece for a couple of seconds between their hands and rub it on their white coat sleeve.

Some stethoscopes are also made of metals that conduct heat less efficiently. Titanium is a good example and will likely feel less cold than solid stainless steel.

Finally, some companies even filled stethoscope warmers patents even though such devices are more anecdotic.

To wrap Up

We hope that you now understand why a stethoscope feels cold. It is all linked to the laws of physics and thermodynamics. Warming up the chest piece is an easy way to minimize discomfort. The key is for the temperature of the chest piece to be as close as possible to the one of the skin.

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