Digital thermometers use an electronic temperature measuring technology. The measured value shows on a LCD display. They allow quick measurements, easy readability and can be acquired at low prices. Digital thermometers are used for rectal, oral and axillary measurements. Another variation is the pacifier thermometer.
Numerous doctors recommend the rectal method to determine the exact temperature, especially if your child is a baby or a toddler. But some studies have revealed weaknesses of this method.
The rectal temperature changes slowly in relation to the core temperature. So the temperature measured in the rectum has been shown to stay elevated for a time after the core temperature has already dropped, and vice versa. Also, the measured values are affected by the depth of a measurement and by conditions affecting local blood flow.
Furthermore, there are health concerns: Cases of rectal perforation have been described. Another problem is, that it is absolutely necessary, to use orderly sterilization procedures. Else, spreading of pathogenic germs that are commonly found in the rectum, may happen.
Many parents do not want to take their kids temperature rectally. And many children, especially older ones, may refuse this method.
It is also the most cumbersome way to measure the temperature: The child has to be undressed, which is complicated at night and also quite unpleasant for the child when the fever is rising, as an increasing body temperature is accompanied by a sensation of cold and the need for some rest.
The digital thermometer placed under the tongue (sublingual) is also one of the common temperature measurement methods. Measured values were found to be about 0,3 degree below the values measured rectally.
The difficulty of this method is, that results can easily be distorted: Oral themperatue measuring relies on the mouth keeping sealed and the tongue pressed down for a few minutes. Children younger than 5 or 6 years are not able to master this, they are prone to bite on the thermometer. So this method cannot be used in younger children. Also, the child has to breath through the nose – difficult, when having a blocked nose or a cough.
For at least 10 minutes before the measuring, the child should not have consumed any foods or beverages as this might distort the measured value.
A general conclusion is, that this method delivers good results with older children. It shows, that accuracy may increase with the age of the child, which is due to the ability to use the correct technique. The preciseness of the oral measurement lies between that of under arm and rectal measuring. Most older children accept this method, as it is not much of an intervention.
On the pro side is that axillary temperature is easy to measure and most kids accept it without any difficulties. This method is the most used one by a number of parents since it is very convenient and without much of an intervention. But young children are not able to seal the axillary as it is necessary to yield a reliable result. The thermometer has to remain directly in place over the axillary artery. Newer thermometers here are patches that can be glued to the skin under the armpit to continuously monitor temperature.
However, in comparison to oral or rectal measurement it is the most inaccurate one. The measurement is quite inexact and is highly influenced by ambient conditions. Approximately 0.5° have to be added to the measured results.
Despite its low sensitivity and significance this method is still considered acceptable if done properly.
Pacifier thermometers are based on a good idea: Many young infants refuse to have their temperature taken, especially through interfering methods. So a pacifier with a built-in temperature sensor seems like a great solution for very young kids. But as obvious as it would appear, it does not work. The reason is, that pacifier thermometers can only measure in the anterior oral area, which often might be a few tenths of a degree colder. So the measured value is of almost no significance. In addition, there are further difficulties: The measurement duration is up to 5 minutes. But babies more often than not spit their soothers out before that time. Also, most babies prefer their usual cherished pacifier, and some babies do not accept any pacifiers at all.