A temporal thermometer is a device that provides a fast, non-invasive method for checking body temperature. This thermometer uses infrared technology to measure heat on the skin’s surface, a convenient alternative to traditional oral or rectal methods. The direct answer to whether you should add a degree is generally no; the temperature displayed is the number you should use for your reading. This popular misconception stems from older thermometry practices that required manual adjustment. The device’s internal programming automatically accounts for the difference between skin surface temperature and core body temperature.
Understanding Temporal Temperature Measurement
Temporal thermometers utilize infrared technology to measure the heat emitted from the skin surface over the superficial temporal artery. This artery is a branch of the carotid artery, which is connected to the heart, giving it a blood flow that closely reflects the body’s core temperature. The artery runs just beneath the skin of the forehead, making it easily accessible for a quick, external scan.
The device does not simply display the surface temperature of the skin, which would be inaccurate due to environmental factors. Instead, it measures the infrared energy radiated from the area and then uses an internal algorithm to convert that surface reading into an estimated core body temperature. This process seeks out the peak temperature detected during the scan, which is the most accurate reflection of the arterial blood temperature.
The thermometer is designed to mimic the internal temperature reading obtained through a rectal measurement, which is considered the gold standard for accuracy. Since the device’s software has already performed the calculation to estimate the internal thermal state, the reading should be taken at face value. Adding an extra degree would artificially inflate the true reading.
Interpreting Temporal Readings and Fever Thresholds
The confusion about adding a degree largely comes from the historical use of axillary, or armpit, temperatures. Readings taken under the armpit are known to be significantly lower than the body’s internal temperature, often requiring the addition of one full degree to estimate an oral or rectal temperature. Temporal thermometers, however, are specifically engineered to eliminate this need for manual arithmetic.
When using a temporal thermometer, the reading on the display is the temperature to record and report to a healthcare provider. The normal range for an adult’s or child’s temperature taken with this method typically falls between 96.8° F and 100.3° F. Knowing an individual’s normal baseline temperature is helpful, as a persistent reading slightly higher than usual may indicate a minor issue even if it is below the official fever threshold.
The accepted threshold for fever when using a temporal artery thermometer is 100.4° F (38.0° C) or higher. This is the same cutoff point used for rectal and ear temperatures. This specific threshold differs from the lower 100° F (37.8° C) cutoff often used for oral temperature readings.
Ensuring Accurate Results: Proper Thermometer Technique
Achieving an accurate temporal temperature relies heavily on correct user technique, as the infrared sensor must capture the heat from the artery effectively. For models requiring a swipe, the process begins by placing the probe flat against the center of the forehead. The measurement button must be depressed and held down throughout the entire scan.
The thermometer should then be slowly and smoothly slid in a straight line across the forehead towards the hairline, near the top of the ear. Sliding the probe in a curved motion or down the side of the face can cause the sensor to miss the superficial temporal artery, leading to a falsely low reading. Once the scan is complete, the button is released, and the reading is displayed.
Several external factors can compromise the accuracy of the reading, including sweat, hats, or hair covering the area. If the forehead is sweaty, the cooling effect of evaporation can cause the thermometer to display a reading that is too low. To compensate for this, some devices instruct the user to briefly touch the soft depression behind the earlobe after the scan.
If a reading seems unusually low or inconsistent, particularly in newborns less than three months old, it may be prudent to confirm the temperature using a rectal thermometer. Ensuring the probe lens is clean is also necessary, as a dirty lens can interfere with the infrared measurements and result in lower readings. Always consult the specific instructions provided with your device, as some newer models may use a no-touch, single-spot method.