Frequently Asked Questions
What if the temporal artery (TA) area has been traumatized by burns or lacerations, or is
completely covered with dressings?
With head trauma, surgical or accidental, the temperature can be obtained from the alternative site behind the ear
lobe. As with diaphoresis, the perfusion will be high in the presence of head trauma.
Why measure behind the ear lobe?
Sweat causes evaporative cooling of the skin on the forehead, and introduces the possibility of a false low
temperature. Fortunately for the method, during diaphoresis the area on the head behind the ear lobe will always
exhibit the high blood flow necessary for the arterial measurement.
Why not use only the area behind the ear lobe?
Since the arterial branch is deeper behind the ear lobe than at the temple, under normal conditions it is less accurate
because of its variability. But under diaphoretic conditions, the blood flow behind the ear lobe is as high as at the TA,
making it as accurate as the TA, but only during diaphoresis or with head trauma as previously mentioned.
How does the TemporalScanner compare to our old method?
Arterial temperature is close to rectal temperature, approximately 0.8ºF (0.4°C) higher than oral temps. Expect larger
differences at times, however, as the dynamics of thermoregulation favor the temporal artery method.
High readings?
Temperatures measured with TemporalScanner may be higher than your current method, especially if you are used to
oral or axillary temps. Oral and axillary temperatures can be misleadingly lowered due to patient activity such as
mouth breathing, drinking, tachypnea, coughing, talking, etc, and periods of vasoconstriction during the fever process.
Any or all of these conditions may even mask fevers that the TemporalScanner will detect.
Low readings?
A patient's temperature measured with the TemporalScanner is normally never appreciably lower than oral
temperature. Lower temperatures are usually from scanning too fast, not keeping the button depressed, a dirty lens,
or a sweaty forehead.
What else should I know?
False high readings:
• Measure only skin that is exposed to the environment. Any covering, hair, hat, bandages,
etc, would prevent the heat from dissipating, causing the reading to be falsely high.
False low readings:
• Multiple readings can cool the skin, so if you take another measurement immediately,
expect a slightly lower reading.
• Slide the thermometer straight across the forehead, not down the side of the face
where the TA could be embedded under cartilage or fat.
• Keep the probe flush on the skin, as in the picture on the right. If angled, you will be
measuring ambient air as well as the TA area.
Conditions that could affect a reading
• Bandages or pressure dressings covering the forehead.
• Forehead abrasions, burns, sweat.
• Agitated or combative patient.
• Patient's forehead in direct draft from vent or fan.
• Thermometer in different ambient temperature than
patient: i.e. window ledge directly exposed to hot sun or
cold weather, or in direct line of air conditioning or fan.
...and their solutions
• If accessible and dry, measure on the area behind the
ear lobe only.
• Consider using the alternate sites: femoral artery, lateral
thoracic.
• The TemporalScanner should be kept in the same
ambient temperature as your patient. Each 10°
difference in ambient can cause a 1° error in the
reading.
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