The temporal artery thermometer, often called a temple or forehead thermometer, is a non-invasive device that measures body temperature using infrared technology. It works by scanning the heat naturally emitted from the skin surface over the temporal artery, a blood vessel just beneath the skin on the forehead. This method is popular because it is fast, gentle, and can be used on people of all ages, including sleeping infants. The thermometer converts the detected infrared energy into a precise temperature reading, offering a convenient alternative to traditional oral or rectal methods.
Preparing for an Accurate Reading
Achieving a reliable temperature reading starts with ensuring the subject and the environment are properly prepared. Since the device measures heat radiating from the skin, anything that alters the skin’s surface temperature can lead to inaccurate results. The scan area must be clear and dry because the temporal artery is located very close to the skin’s surface.
Before taking a reading, ensure the thermometer’s sensor lens is clean, as dirt or smudges interfere with the infrared scanning technology. The forehead and temple area must be free of physical obstructions, such as hair, hats, or headbands, which could insulate the area and cause a falsely high reading. Cosmetics, makeup, or sunscreen should also be avoided on the scanning path.
Environmental factors also play a role in accuracy, so the subject should be in a stable room temperature environment for several minutes before the scan. If the person has recently come indoors from extreme cold or heat, or if there is visible sweat, the reading may be artificially low due to evaporative cooling. If sweating is present, wait 10 to 15 minutes for the skin to dry and acclimate before attempting a measurement.
Step-by-Step Guide for Temple Scanning
An accurate temporal artery reading requires correct and continuous physical scanning motion. Begin by turning the device on and ensuring specific settings, such as adult or child mode, are selected according to the manufacturer’s instructions. Place the thermometer probe flush against the center of the forehead, maintaining gentle but firm contact with the skin.
Next, press and hold the scan button, keeping it depressed for the entire measurement process. While holding the button, slowly and smoothly slide the probe in a straight line across the forehead toward the hairline. Avoid lifting the device or curving the scan downward toward the cheek, as this can cause you to miss the most superficial part of the temporal artery.
Continue sliding the thermometer until you reach the hairline near the ear. For maximum accuracy, some devices recommend continuing the scan until the probe gently touches the soft depression on the neck just behind the earlobe. This secondary spot, often referred to as the “perfume spot,” can provide a reference reading, especially if the forehead is sweaty. After completing the full scan, release the button and read the displayed temperature.
Understanding and Troubleshooting Results
The temperature displayed is an estimate of the body’s core temperature, which is considered stable across different measurement sites. A normal temperature range is variable, but a reading of 100.4°F (38°C) or higher from a temporal artery thermometer is considered a fever. This threshold is consistent with rectal or ear measurements, though temporal readings may sometimes be slightly lower than rectal readings.
If the reading seems unexpectedly low, a common cause is scanning too quickly or releasing the scan button prematurely. The device needs continuous contact and enough time to take hundreds or thousands of measurements to find the highest, most representative temperature over the artery. A dirty probe lens or a forehead cooled by sweat or a cold draft can also lead to an artificially reduced temperature.
If you receive an error message or an inconsistent reading, re-scan on the opposite side of the forehead, as temperature can sometimes vary between the two sides. If the subject is fully covered in sweat or diaphoretic, the cooling effect can make any forehead reading unreliable. In this case, an alternative site or waiting for the skin to dry may be necessary. When discussing a temperature reading with a healthcare professional, always specify that the measurement was taken using a temporal artery thermometer.