Figure 1: Different locations to measure body temperature.
Before we discuss how to measure your client’s temperature, we need to cover some definitions. Our body is always generating heat through metabolism, and a part of the brain, called the hypothalamus, tries to keep the core body temperature constant like a thermostat. When we are febrile, meaning we've got a fever, the thermostat is raised higher, and this can be due to an infection, inflammation, or cancer. However, body temperature could also be high in hyperthermia (Fig. 2), where the thermostat is set at the right temperature, but the body simply can’t get rid of the heat. This can be due to an extremely hot environment, excessive exercise, and reduced sweat production. In contrast, hypothermia (Fig. 2) is when body temperature gets too low, and it might be due to exposure to cold for a prolonged period of time, either accidentally or in preparation for a medical procedure.
Figure 2: Physiology of body temperature.
Figure 3: Supplies and steps for taking an oral temperature. A. Supplies needed. B. Ask client to open their mouth, and insert sheathed thermometer into one of the sublingual pockets. C. Ask client to keep their mouth closed for 20–30 seconds. D. Remove thermometer and discard used sheath appropriately.
If the client is comatose, confused, critically ill, in a shock, or unable to close their mouth, obtaining a rectal temperature would give the most accurate measurement. The rectal temperature is normally 0.7–1°F (0.4–0.5°C) higher than the oral temperature. This means it should be between 98.6–100.6°F (37–38.1°C) for adults, and 98–100°F (37–38°C) for children.
However, this method is often uncomfortable, both physically and emotionally, and it’s also riskier than the other methods. It should be avoided in clients with hemorrhoids, diarrhea, lesions around the anus, or those who have recently had surgery involving this region. Furthermore, the thermometer can stimulate the vagus nerve found inside the rectum, which could trigger a reflex that slows down the heart rate and lowers blood pressure, so clients with heart conditions should also avoid this procedure.
Figure 4: Supplies and steps for taking a rectal temperature. A. Supplies needed. B. Help client roll over into Sims' position, and expose client's buttocks. Slide sheath over probe and apply lubricant jelly. C. Insert lubricated probe into rectum approx. 3 cm deep towards umbilicus. D. Hold thermometer there for 20-30 seconds. Remove thermometer and discard used sheath appropriately.
You can then remove your gloves and practice hand hygiene. Return the side rails to the raised position, adjust the height and head of the bed, help the client move back into a comfortable position, and make sure that the wheels are locked. Finally, the thermometer needs to get ready for its next use, so, for an electronic thermometer, switch it off, put away the probe, and thoroughly clean and sanitize it before putting it on charge.
The tympanic membrane thermometer, or TMT, measures the temperature from a client’s eardrum. It’s almost as accurate as rectal temperature if done properly, but accuracy might be affected by ear infections, like otitis media or a buildup of cerumen, or earwax. A normal tympanic membrane temperature is 98.6°F (37°C) for adults and 98–100°F (37–38°C) for children.
Figure 5: Supplies and steps for taking a tympanic membrane temperature. A. Supplies needed. B. Check for hearing aids and remove. If there is too much wax, use a warm washcloth to wipe ear canal. C. Slide probe sheath over thermometer's probe. D. Place probe tip in ear canal, pulling back and up for an adult and straight back for a child. Press and hold button until probe chimes, approx. 1 second. Remove and discard of used probe sheath appropriately.
This method is the safest but the least accurate. You can use it on newborns or unconscious people if other methods cannot be obtained. A normal axillary temperature falls between 96.6–98.6°F (36–37°C) for adults and 96–98°F (35–36°C) for children.
Figure 6: Supplies and steps for taking an axillary temperature. A. Supplies needed. B. Slide probe sheath over probe. C. Ask client to expose and lift arm. Use a paper towel to softly dry the axilla. D. Center probe in axilla and fold arm down. Hold probe in place until it chimes. Remove and discard used probe sheath appropriately.
Figure 7: Supplies and steps for taking a temporal artery temperature. A. Supplies needed. B. Place the sensor on the forehead, hold the scan button, and slide thermometer steadily across forehead.
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