How to Use a Thermometer

How to Use a Thermometer? A Complete Guide

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Of all the instruments and tools regarded as important in clinical examination, none has had widespread application than the clinical thermometer. The clinical instrument has experienced a rudimental evolution from thermoscope, the first instrument used to measure temperature, to now the new digital thermometer. The first modern thermometer with a standardized scale was invented in 1714 by Daniel Gabriel Fahrenheit, after which it incorporated the modern Celsius scale invented by Anders Celsius in 1742.

When dealing with recurrent fevers in both adults and children, it is common to be concerned about the best way to use a thermometer and record accurate readings. There are mainly four methods that you can use a thermometer namely: orally (mouth), rectal (anus), axillary (armpit), and tympanic (ear). However, the different methods of measuring temperature readings produce accurate but different average readings.

This article will offer 360 degrees insight on the best way to use a thermometer and record accurate temperature readings.


Different Types of Thermometers 

Before delving deeper on how to use a thermometer, it is essential to first have a clear understanding of the different types of thermometers. There are mainly five types of thermometers that you can use to measure temperature readings as outlined below.

1. Glass thermometers

Glass thermometers, just like the name suggests, comes with a glass body. The thermometer contains mercury that expands and contracts with the change in temperature. Some of the main drawbacks of these thermometers are that they are difficult to read and measure temperature readings slowly. You should never use glass thermometers to read children’s oral temperatures, as they can bite them and cause safety concerns due to broken glass and mercury.

2. Digital electronic thermometers 

Digital thermometers use heat sensors to measure temperature readings and are powered by button batteries. Their heat sensors use the latest technology to measure temperature readings, which underlines their high speed, usually in seconds. The temperature readings are then displayed on the thermometer’s screen in numbers for easy reading.

You can use digital electronic thermometers to measure rectal, oral, and axillary temperatures. Digital electronic thermometers come in different shapes and sizes and you can get them in a majority of the pharmacies and supermarkets at a wide range of prices.

3. Ear Thermometers 

Ear thermometers are infrared thermometers used to read eardrum temperatures thus providing accurate temperatures as those of rectal. These types of thermometers read temperatures in seconds, thus being among the fastest thermometers in the market. Also, ear thermometers do not cause any discomfort and don’t require the cooperation of a child.

Most of the ear thermometers retail at an average price of $30 to $40 and comes in different sizes, types, and shapes. According to the American Academy of Pediatrics (AAP), electronic ear thermometers should never be used to read infants’ eardrum temperatures, as their ear canals are too small. Learn How to Use Ear Thermometer?

4. Temporal Artery Thermometers 

Temporal artery thermometers are infrared thermometers that read blood temperatures in the temporal artery. This is the blood artery that crosses through your forehead often visible after body exercises. Temporal artery thermometer temperature readings tend to be more accurate than those of the ear thermometers.

The strong point of these thermometers is that they take temperature readings within seconds and do not cause any discomfort. However, to acquire one, you must dig deeper into your pockets as they are the costliest thermometers currently, retailing at over $60.

5. Digital Electronic Pacifier Thermometers 

Digital electronic pacifier thermometers, just like digital electronic thermometers, read temperature readings with the use of heat sensors and are powered by button batteries. They are ideal for measuring children’s oral temperatures and are used by placing them in the mouth for at least 3 minutes, something which is not possible for toddlers.

How to Take Rectal Temperatures

Reading rectal temperatures is one of the most accurate and effective ways of measuring body temperatures. A digital electronic thermometer is the best thermometer used to measure rectal temperatures. Note that rectal temperatures tend to be one degree more than axillary and oral temperatures.

Below are the correct steps that you should take when using the digital electronic thermometer to measure rectal temperatures.

Turn the thermometer on 

To use a digital electronic thermometer, you must first turn it on by pressing the power button. Ensure that it is in the right condition and the batteries are working for accurate temperature readings. Also, ensure that your digital thermometer is calibrated correctly and all the settings are okay.

Lubricate the thermometer

When taking rectal temperatures, you should shy away from causing any discomfort, that’s why you should consider buying a digital thermometer with a flexible tip to ease the insertion process. Besides, you must first apply the digital thermometer with a water-based lubricant on its end as well as the bottom (anus) opening before inserting the thermometer, to ease the process. Also, lay at a good angle that will enable you to reach the bottom easily and remain still but comfortable.

Insert the thermometer 

After ensuring that both the thermometer and the bottom are well lubricated, insert the digital thermometer gently into the bottom at least 1 inch. In case you are taking the temperature readings of a child under the age of 6 months, insert the thermometer about a quarter or half an inch to avoid discomfort. Keep in mind that you should never force the thermometer against any resistance to avoid damaging the bowel.

Wait for the beep sound 

When using a digital thermometer, you don’t need to worry about how many minutes the thermometer should remain in the bottom. Once you have inserted the thermometer, all you need to do is wait for the beeping sound, which indicates that it has read the temperature. After hearing the beeping sound take the thermometer out and read its readings, if over 38 degrees Celsius you might be having a fever and thus need medical attention.

Clean the thermometer

After reading and recording the rectal temperatures, gently clean the thermometer using a clean sponge dipped in clean lukewarm water or alcohol to kill germs. Rinse the thermometer with clean water to remove alcohol and wipe it with a clean cloth or towel and return it to its case for storage. Ensure that your rectal thermometer is labeled to avoid using it orally for hygiene reasons.

How to Take Axillary (armpit) Temperatures?

Axillary temperature is one of the most common ways that people use when measuring their body temperatures. The method is not only safe but also gives a quick temperature reading at minimal expense and effort and doesn’t cause any discomfort. However, it doesn’t give accurate and reliable body temperatures as it registers 1 degree lower than that of rectal temperatures.

The good thing with axillary temperatures is that they can be taken with both standard and digital thermometers. Below are the steps that you should take when taking axillary temperature readings using a thermometer.

Turn on the thermometer 

In case you are using a powered thermometer, you will need to turn it on before placing it under the armpits. Similar to measuring rectal temperatures, you must ensure that your thermometer’s batteries are working correctly and that it is calibrated correctly to give accurate readings. Consider taking axillary temperatures of both armpits for better temperature accuracy and pick the highest readings.

Place its tip under the armpits 

Before placing the thermometer under the armpits, you must ensure that your armpits are clean and dry by gently cleaning them using a tissue. Avoid taking a hot or cold shower before taking axillary temperatures or doing body exercises as it will affect your body temperature readings. For optimal body temperature readings, place your thermometer in the deepest part of your armpit.

Close the armpit 

Consequently, close your armpits tightly by holding your hand against the chest to hold the thermometer in place and tap the body heat. Let the thermometer rest under the armpit for about 4 to 5 minutes or until it beeps, for digital thermometers. When removing the thermometer from your armpits, do not touch its tip to avoid distorting its readings, but wipe it with clean tissue paper.

Read its temperature readings 

After the 4 minutes, take the thermometer out of the armpit to read the body temperature readings. The average axillary temperature should be between 35.9 degrees Celsius and 36.7 degrees Celsius. Normally, axillary temperatures are usually 1 degree Celsius lower than those of other temperature reading methods.

In case you are not sure with the armpit readings, you could confirm by measuring rectal temperatures and compare the two. However, remember that rectal temperatures are usually one degree higher than that of axillary temperatures. If your axillary temperature readings are above 38 degrees Celsius, then you might be suffering from fever and you need medical attention.

How to Take Oral (mouth) Temperatures

The average oral temperatures for children ranges between 36.4 and 37.4 degrees Celsius, while that or adult is 37 degrees Celsius. Anything higher than that indicates that you are suffering from fever, and you need medical attention. However, it is important to note that oral temperatures vary depending on your activity.

Avoid taking cold or hot drinks or eating food before taking oral temperatures, to avoid reading inaccurate temperatures. Below is a guide of how to take oral temperatures.

Clean the thermometer’s tip 

Even though your thermometer may look clean, chances are that it might have accumulated some pathogens during storage that could be harmful to your health. That’s why you must first clean it using clean lukewarm water, rub it with alcohol, and rinse it with clean and cool water. Subsequently, you could use a throw-away cover if you don’t want to clean the thermometer but ensure that it is also clean.

Place the thermometer’s tip under the tongue 

Open your mouth and place the thermometer’s tip under the tongue close your lips gently. The accuracy of your oral temperature thermometer will depend on where you place it in the mouth. Consider placing it at one side of the tongue and towards the back of your mouth for accurate readings. Avoid breathing through the mouth while the oral thermometer is in your mouth, to avoid distorting its readings and to keep your mouth closed.

Let the thermometer settle 

After placing the thermometer under your tongue, you should let it settle for about 4 to 5 minutes or until it beeps, for the digital thermometers. Remove the thermometer from your mouth, clean it gently using tissue paper to remove saliva, and read your oral temperatures. In case your oral temperatures exceed 38 degrees Celsius, then you could be suffering from fever and you need medical attention.

How to Take Tympanic (ear) Temperature 

Taking tympanic temperatures is one of the most accurate ways of measuring body temperatures. For accurate ear temperature readings, you must have spent at least 15 minutes indoors before taking the measurements. However, it is essential to note that ear infections, ear wax buildup, laying on an ear, and the angle of the thermometer can affect its readings.

Tympanic thermometers measure tympanic pressure by sensing the reflected infrared emissions generated from the tympanic membrane (eardrum). Here is how you can take tympanic temperatures.

Clean your ear thermometer 

Ear thermometers might contain pathogens that once introduced in your ear canal can cause ear infections. This being the case, you must clean your ear thermometer before use to clear all the pathogens that it might have accumulated on it. Thus, gently clean the tympanic thermometer with clean lukewarm water, apply alcohol on its surface to kill germs, and rinse it with cool water to remove the alcohol.

Straighten your ear canal 

Placing the tympanic thermometer in the curved and small ear canal can cause discomfort and will give inaccurate readings. That’s why you must straighten your ear canal before inserting the thermometer in your ears, to ease the process. Straightening your ear canal should not be a hard nut to crack, as all you need is simply pull your ears backward,

After ensuring that your ear canals are straight, you can then place the thermometer in them while aiming its probe towards the eye located on the opposite side of the head. After ensuring that it is in the right position, press the tympanic thermometer button to start reading your body temperature.

Let it settle in the ear canal 

The good thing with tympanic thermometers is that they are very fast, taking at least 2 seconds to read body temperatures. Once your tympanic thermometer has read your body temperatures, it will make a beeping sound to alert you when to remove it. After removing it from your ear canal, clean it gently using tissue paper and read the temperature readings. For optimum and accurate tympanic readings, take the temperatures of both ears, compare the two readings, and pick the highest.

How to Take Temporal Artery Temperatures

Taking temporal artery temperatures can only be done using an artery thermometer that uses infrared heat waves to read body temperatures. Temporal artery temperatures are among the most accurate readings and can be used as a reference point by oral or armpit temperatures. Here is how you should take temporal artery temperatures.

Place the thermometer on your forehead 

Temporal artery thermometers have sensors responsible for reading the blood temperatures in the temporal artery. The temporal artery is located at your forehead and close to the skin running across your head. That’s why you need to place the sensor head of the temporal artery thermometer at the centre of your head between the hairline and the eyebrows. Learn How to Use Temporal Thermometer?

Depress the scan button 

After ensuring that you have placed the temporal artery thermometer in the right place, hit the scan button on the TA thermometer to start scanning. Keep the scan button depressed until it completes scanning, for accurate temperature readings. Releasing the scanning button too soon will give low and inaccurate temperature readings.

Slowly slide the thermometer across your forehead towards the ears, ensuring that it is in close contact with your skin. Keep in mind that different TA thermometers have a different method of use and you will need to go through your thermometer’s user manual.

Release the scan button 

After reaching your hairline, release the scan button and remove the TA thermometer from the skin. The thermometer will display your body temperatures on its display screen located on the upper side of the TA thermometer. In case your body temperature readings exceed 38 degrees Celsius, know that you might have a fever attack and will need to seek medical attention as soon as possible.

Bottom Line 

When all is said and done, your health should come first in your pecking order and that’s why possessing a clinical thermometer is essential. However, you must first know how to accurately use the thermometers, to get accurate temperature readings. By following this guide, you will be able to.

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