When our firstborn arrived 4 months ago we faced the need to buy a baby thermometer. After some deliberation I decided to splash out and buy a ThermoFlash LX-26. I'm very happy with the device, it's extremely easy to use and gets a reading in a fraction of a second. Perfect for a baby.

However even after 4 months of use I'm still unsure how to use it correctly! Both their manual and their webpage are quite laconic and not very helpful. The closest they have is this:

Hold the Thermo-flash LX-26 between 5 and 15 centimeters from the forehead.

Press the mesuring touch at the front of the handle, after the beep the temperature shows up immediately on the LCD screen.

Now, this is neither precise nor accurate. First of all, check out how it looks from the front:

As you can clearly see, the sensor is at the bottom of the device. This is in contrast to the first picture, where it is shown to be on the top... sort of.

Secondly, 5cm is about half of the distance between the device's front and back. So the distance in the first picture is way off as well.

How should I then be positioning it? Should I point the sensor at the forehead, or should I point it as shown in the picture (the sensor then faces the eye of the baby)? I've tried both ways, and the eye measurement is always hotter than the forehead measurement. Usually it is about 0.2°C to 0.3°C hotter, but sometimes it can be as much as 1°C hotter. Today too I measured 36.3°C on the forehead and 37.3°C in the eye.

So... how is this done correctly?

P.S. Someone with more rep, please set the tags to "infrared-thermometer temperature usage". As a new user, I can't create new tags... :(

asked 16 Jan '10, 21:01

Vilx-'s gravatar image

accept rate: 0%

edited 16 Jan '10, 21:25

Rich%20Seller's gravatar image

Rich Seller

Wish I could help, but never seen one like this. We've got an electronic 'in the ear' variety, which seems to work, but no idea how accurate it is. (http://braun.kaz.com/kaz/product/?prodId=8536e428608f5dd68ce14fe2e28d4f82). Nothing beats lips to forehead :)

(16 Jan '10, 22:07) Benjol

Yes, I considered this one as well. But the ThermoFlash one seems to be more popular around here. Also the doctors at the hospital where our child was born used this device, and that lends something to its credibility. And the store where I bought it only had the ThermoFlash. :)

(16 Jan '10, 23:24) Vilx-

From a quick search, this doesn't appear to be available in the UK. We have an in the ear at the moment. It's not bad, but can vary by over 1 degree C depending on how you aim it. My wife has got the hang of it, I'm less reliable. We've only had the thing for 10 years! I look forward to being able to get one of these. Maybe my industrial non contact thermometer could work, just need to be careful with its laser sight. :)

(17 Jan '10, 13:49) pipthegeek

The technology being used is an infrared heat sensor very similar to those used in industrial, electronic, and other professions, and it essentially the same technology used for ear measurements, just on a different part of the body.

The manual shows that the accuracy is +/- 0.3 C/F, with a precision of +/- 0.2 C/F.

This concerns me because they say it's +/- 0.3 degrees accurate on both C and F scales, which technically is impossible - it cannot be both - 0.3 C is not equal to 0.3 F by almost a factor of 2. At minimum I'm curious what the real accuracy is.

Regardless, a variation of up to a degree would not surprise me (worst case accuracy + precision in C, converted to F is about 1 degree F), even measured in the same location. Don't worry too much about a 1 degree C or F variance.

The device has a wide beam spread, which is why you must hold it close to the head (5cm is about 2 inches). Just aim the window at the child's forehead within 2 inches and you'll get as good a reading as this device will take. It will take a better reading the closer it is, so if you are unsure about your aim, go ahead and place it closer, or even against the skin (gently!). The window is the measurement area, and the intention is to measure the temporal artery (blood flow through a portion of the forehead) so the correct aim to for the window to face the forehead.

This is perfectly fine for fever indication. In other words don't worry too much about the absolute temperature - just whether it indicates there's a fever, and if so then you should consult with your doctor. Also note that the precision is better than the accuracy - this means that reading-to-reading you should receive similar results, so measure when you know your child doesn't have a fever, and use that as a baseline for this device. You will at least be able to tell how elevated from normal the fever is.

When doctors ask what temperatures you are seeing, be sure to mention the method you took it with (they almost always ask us anyway, there are so many ways to take a temperature) and they will take that into account when assessing your situation.

It's not a bad technology, it's being used very successfully in many other situations, but it's relatively new for measuring the temporal artery. Like most home thermometers of all types, it's meant for indication, not diagnosis.

If you need more assistance, bring it with you to your to your child's next checkup and have the nurse or doctor show you how to use it. They may be able to give you additional information on this type of measurement.


answered 17 Jan '10, 05:58

Adam%20Davis's gravatar image

Adam Davis
accept rate: 31%

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Asked: 16 Jan '10, 21:01

Seen: 12,194 times

Last updated: 17 Jan '10, 05:58