thermometers

There are several devices available to measure a child's termperature.

The oldest method for "measuring" temperature was the "feel the forehead" method, used by mothers from before recorded history. I once read a study that showed that mothers asked to rate the temperature as a low, moderate, or high fever actually do this fairly reliably, within a degree or so. To be truthful, that is often close enough for management of ordinary childhood illness. But we seem comfort when things - especially mysterious things like fever that we fear - are quantified into a number¹. So it is "technology to the rescue."

The second oldest, the mercury-filled glass thermometer, is passing from the scene. They are now banned for sale in the US due to the possible release of mercury into the home environment in case of breakage. They were quite accurate, especially if used in the preferred method for young children, namely rectally. Drawbacks included difficulty reading them properly, especially by non-professionals.

Electronic ("digital") thermometers were a great step forward. They are very cheap and accurate. They are easy to read correctly. I recommend them to my patients.

Tympanic ("ear") thermometers were the next big advance in temperature technology. These units read the intensity of infrared radiation (that is, heat) coming from the eardrum. This temperature is closely correlated with the temperature of the blood passing through the liver, which we call the "core temperature." I bought the first one in town over 20 years ago, and the other doctors in my group had to follow suit when their patients' parents complained about rectal temperatures. Advantage: no rectal "assault." Disadvantage: spotty accuracy, especially in inexperienced hands. If one does not do these all the time, results can be unreliable. When tympanic thermometers eventually became avail to the public this became more of an issue.

The "latest and greatest" thermometers are the temporal artery scan units. Like tympanic thermometers, these read infrared radiation, but from the forehead, which is supplied with fresh hot blood from the temporal artery (main artery of the temple, found pulsing just in front of the earlobe). These thermometers are said to be (and seem to be) more accurate than tympanic units, and are much simpler to use. The device is just "wiped" across the forehead, and reads instantly.

Both the tympanic and temporal artery thermometers should be set to read a rectal (core) temperature equivalent. These are the only measurements of real usefulness in medical care. I always advise patients to report not just the temperature, but how they took it (rectal, oral, or underarm [axillary]), without adding or subtracting anything.

1. I knew a pediatrician in the days before ear thermometers who did not take temperatures in the office for a time, saying (truthfully) that they just upset the kids and did not add anything to office management of illness that a hand on the forehead could not accomplish. I don't know how long he lasted at this, but I suspect patients eventually pressured him back into taking temperatures.

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