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Everything You Need to Know about Temporal Thermometers

By CME Corp Staff | June 20, 2020

What is a temporal thermometer? Temporal thermometers contain an infrared scanner measuring the heat on the surface of the skin, which results from blood moving through the temporal artery in the forehead. This type of thermometer is non-invasive and may even be applied while a patient is sleeping.

In Exergen models, two tasks are being performed by the thermometer as it scans. First, it searches for the naturally emitted infrared heat produced from the arterial blood supply, locking in the highest temperature it senses. During that scan, the system measures the ambient temperature of the area where the temperature is being taken. The thermometer then evaluates and formulates the two separate readings into an accurate body temperature.

Choosing a temporal thermometer 

What is the best temporal thermometer? Exergen Temporal Artery Thermometers have quickly become the gold-star standard in forehead thermometers. Selecting the right model is dependent on your level of use. With multiple models available, it is important to understand the differences found in each unit. 

The three most common models are the Exergen TAT-5000, TAT-2000 and TAT-2000C. Let’s deep dive into each unit to understand which one is right for you, as well as address commonly asked questions about temporal thermometry.

Exergen TAT-5000, TAT-2000, and TAT-2000C

For those searching for the most accurate, non-invasive thermometer on the market, the Exergen TAT-5000 is your solution. The TAT-5000 easily handles the demands of a high-performance hospital environment as a durable device designed for frequent use and easy cleaning.

Often found in intensive care units and emergency departments, the durability of this model has been proven. This model allows the choice of using disposable covers, or cleaning between patients with a disinfectant wipe, providing cost savings by eliminating or substantially reducing probe cover usage. Exergen states this feature provides payback for full hospital installation in less than one year. Exergen also backs the product with a Lifetime Warranty. 

The Exergen TAT-2000C is an entry-level model, designed as a light-duty and budget-friendly option for home use. With an easy-to-clean reusable tip, this model is perfect for the home and would make a great addition to your medicine cabinet. Enhancing the “original” model, this unit added a bright LCD screen and memory feature and was clinically proven to be as accurate as rectal thermometers. 

Those who are looking to capture the same professional grade of a model as those used by a school nurse, pediatrician or other clinical environments may opt for the Exergen TAT-2000. This model keeps the ease and speed of use found in the TAT-2000C, but allows an option to use disposable probe covers and is accompanied by an increased 3-year warranty from the TAT-2000C’s 1-year policy.

Additional features include storage memory for eight readings, with the most recent temperature stored in the first location spot, slot 1. Perfect for nursery use, the beeping notification that indicates an occurring scan can be turned off or on to avoid waking a sleeping patient. 

Regardless of your final decision, Exergen TAT models are often marketed as the #1 thermometer preferred by pediatricians, nurses, and moms. With their ease of use and accuracy, it is easy to understand why.

How do you take a forehead temperature? 

Place the temporal thermometer probe on the center of the forehead and slowly slide the unit across the forehead towards the top of the ear. You can stop your slide when you reach the hairline next to the ear. Do not curve your swipe towards the actual temple or you could miss the important part of the temporal artery in the forehead and decrease your result accuracy.

How accurate is a temporal thermometer?

Temporal thermometers have become the preferred method of taking a temperature for most kids 3 months and over, particularly for screening when you can’t or prefer not to do a rectal temperature. Temporal thermometers take advantage of the temporal artery’s location as it is an easily accessible artery with constant blood flow. This combination, along with the arteries' shallow depth from the skin surface, provides the scanner a clinically accurate and noninvasive way of taking a temperature measurement.

While the standard rectal thermometer was believed to be the most accurate method for taking a temperature, its invasive design has made home use often uncomfortable for the patient and caregiver.  Here is a graphic illustrating the reading variations found in methods of measurement. 


Temperature Chart 1Temperature Chart 2

As a reference, the average normal oral temperature is established as 98.6°F (37°C). Rectal temperature is 0.5°F (0.3°C) to 1°F (0.6°C) higher than an oral temperature. Ear (tympanic) results may also be 0.5°F (0.3°C) to 1°F (0.6°C) higher than an oral temperature.

It is common for an armpit (axillary) temperature to register 0.5°F (0.3°C) to 1°F (0.6°C) lower than an oral temperature, but most professionals suggest passing on this method due to the difficult task of placing the thermometer in the proper position. 

Even though there are noted discrepancies in measurement based on method, the key to your accuracy is picking a thermometer and staying with it. Use the same type of thermometer, and if you can, the same unit- every time. This allows you to know a normal temperature range and any flares or fevers through a controlled apparatus. 

In addition, temporal scanning was proven more accurate than ear thermometers by a Harvard Medical School study. Ear thermometer accuracy is often considered flawed because of inconsistencies in the positioning of the probe in the ear canal. Temporal artery thermometers ease of use makes it near impossible to miss the temporal artery, offering consistency and accuracy to results.

Are you supposed to add a degree to a temporal thermometer? 

This idea stems from early reports on the noted variations between a temporal thermometer and oral/rectal results. The belief was that you would need to adjust your reading to coincide with the accuracy of other methods. It has since become a common consensus that there is no need to adjust your reading, thanks to various studies occurring since temporal reading inception.

The general consensus has been more focused on not mixing measurement methods. For example,  using an oral thermometer for one reading and later checking the temperature with a temporal unit is prone to more inaccuracies and differences than using one method of measurement consistently. This consistency in application is viewed as more important than the need for adjusting temperature scales. 

Currently, arterial temperature measurement leads all other methods in identifying fever and temperature change. The method is unaffected by activities of daily living, and while it will sometimes reflect different temperatures from other methods, it is still accurate in its measurement.

What is considered a fever on a temporal thermometer

A fever can be declared when your temporal artery thermometer registers a temperature of 100.4 F (38 C) or higher. 

Why am I getting inconsistent results from my TAT thermometer 

You should not experience large discrepancies in readings; however multiple scans occurring in succession may cool the surface area of the forehead and result in subtle differences. 

You may need to clean your unit. The scanners use optical technology, and the infrared sensor (which is behind the lens) must “see” the heat in order to measure it.

Another common error occurs when the scan button is released too soon. Exergen forehead thermometers need to scan the entire temporal artery from center forehead to ear, with the user holding the scan button down the entire time. Releasing this button too soon can result in an inaccurate and often lower reading.

During a fever, the body may attempt to lower its temperature naturally through sweating, which also causes extra cooling of the skin. As a result, you may see a reading that is too low. You may choose to wait until the sweating has stopped, or use a different scanning method also proven to provide accurate results.

To handle sweat:

  1. Scan the temperature as normal, keeping the button depressed

  2. Gently nestle the TemporalScanner on the neck, directly behind the earlobe. Think of this spot as the same location where you would spray perfume.

  3. Release the button and read the temperature 

Please know that wiping the forehead to remove or dry sweat before taking a reading is not recommended as the sweating will immediately begin again. 

How do I clean my Exergen TAT thermometer?

Twirl an alcohol-moistened Q-Tip directly on the lens located in the center of the probe head. This preventive maintenance should be done routinely, every few weeks. Please be sure to wait five minutes to let the infrared sensor recalibrate from the coldness of the alcohol cleaning before using your unit.

What battery is used in an Exergen TAT thermometer? 

Exergen TAT-5000, TAT-2000, and TAT-2000C all require a 9V battery. 

What does LO mean on my Exergen thermometer? 

Exergen TAT thermometer are sensitive to ambient temperature. The LO message indicates that the ambient temperature of the unit is not the same the individual whose temperature is being taken. No need for concern, just let the thermometer adjust to your current setting, and the indicator should clear. 


About CME: CME Corp is the nation’s premier source for healthcare equipment, turnkey logistics, and biomedical services, representing 2 million+ products from more than 2,000 manufacturers.

With two corporate offices and 35+ service centers, our mission is to help healthcare facilities nationwide reduce the cost of the equipment they purchase, make their equipment specification, delivery, installation, and maintenance processes more efficient, and help them seamlessly launch, renovate and expand on schedule.

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