The accuracy of wrist temperature scanning.

Body temperature varies from person to person, and certain things can affect it, such as gender, age, and ambient environment. Women often have a higher body temperature than men, older patients a lower body temperature, and sometimes a baby's temperature is slightly higher. Other factors influence body temperatures like stress, metabolic disturbances, illness, medication, and surgical procedures. With this in mind, normal body temperature can vary from 96˚F to 99.7˚F, but anything reaching 100.4˚F or above is considered a fever. It will also differ depending on the method used to take the temperature, and these methods have changed and developed over the years.

Medicine and technology are ever-evolving.

The COVID-19 pandemic has seen research, medicine, and technology develop at jaw-dropping speed. This is a good thing! It is how the world of science and medicine evolves. Over the decades there have been many medical decisions reversed and new technologies developed. In fact, a study published in eLife reported that of 3,017 studies analyzed from the last 15 years, 396 came to conclusions that reversed prior treatment recommendations. Some of these decisions directly impact our everyday lives. One nursing journal discusses that nothing will change healthcare practice more than the advancement of technology - it not only changes techniques but the accuracy of testing, recording, and tracking results. Therefore, although technology is developing at break-neck speed in this pandemic, it is a positive step forward to managing the 'new normal'.

Thermometers have changed.

In the past, I am sure you have had your temperature taken in several ways: under your armpit, under your tongue, across your forehead, or in your ear. Traditionally, mercury glass thermometers were the instrument of choice to take a temperature, but these have been phased out. No matter how careful, there is always a risk of glass breaking and mercury released into the environment from a broken thermometer is poisonous. Over the years, various types of digital, tympanic, and infrared thermometers have become the trusted way of recording temperature. Not only are they often less invasive and more comfortable for the patient, but with no touch versions and disposable covers, there is less risk of cross-infection. As technology has continued to develop, there is now a multitude of temperature technology available to scan people quickly and easily.

The 'new normal' of temperature recording.

With global travel now accessible to just about anybody, transportation of infectious diseases across international borders is a very real problem. Due to the arrival of COVID-19, temperature scanning has become the 'new normal' as a safety measure. The worldwide prominence of COVID-19 has prompted use of mass temperature screening methods to delay the transfer of infection into healthcare settings, workplaces, communities, and countries. Fever is one of the key symptoms, therefore temperature screening in public places allows for early identification of COVID-19 and helps reduce the risk of cross-infection.

New temperature scanning methods.

With temperature screening becoming a normal part of everyday life, a swathe of new temperature screening systems have been developed over recent months. Infrared thermal detection systems have become more popular as an alternative to using contact thermometers. This type of technology can work on different parts of the body, including the forehead and wrist. Without touching the skin, infrared thermal detection is quick, non-invasive, requires no wasteful covers, and no risk of cross-contamination. We are all familiar with having temperature recorded in our ear or over our forehead. However the latest change in temperature screening is to scan the wrist rather than the forehead. So how accurate is wrist temperature scanning?

How accurate is the wrist when taking temperature?

Previous studies show that armpit and rectal temperature are the gold standards for recording temperature, however, this is entirely impractical for public and large-scale screening. Therefore, a recent real-world study investigated the reliability and accuracy of wrist and forehead temperature measurement when conducting mass screening. When using non-contact, infrared thermometer technology, wrist temperature measurement was more stable than the forehead measurement in outdoor participants. Both wrist and forehead measurements were found to be equally accurate when screening patients indoors.

Why does the indoor/outdoor environment matter?

Well, when taking the temperature with a non-contact method, it can be affected by the surrounding environment. Entering a building from cold weather can make temperature readings inaccurate when measured on the forehead. As the wrist is often covered by clothing, taking the temperature from 10cm above the wrist meant that the environment did not affect the temperature reading, showing the wrist to be more accurate in this recent study. In other research conducted earlier this year, a wearable wrist temperature device was tested on patients in hospitals with kidney disease. This study identified that using a wearable wrist temperature device was accurately able to detect raised temperature and infection. Therefore, this type of wrist device could be used as a preventative measure to identify and treat early infection in those at risk.

What are the benefits of taking a wrist temperature?

Does it matter from which part of the body you take a temperature? As discussed above, it does matter if a person is exposed to an outdoor environment as this affects the result. There are also other things to be considered aside from accuracy, like cost. Using a tympanic thermometer in the ear means using a disposable probe cover which incurs considerable financial and environmental cost. It is also not conducive to mass temperature checks in a public setting. Therefore wrist temperature has the benefits of being quick, accessible, non-invasive, cost-effective, and un-effected by the environment.


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