Assessment of Body Temperature

Study Notes

Sites for taking temperature should be closed to prevent air currents and have an abundant blood supply.

A rich blood supply under the tongue makes it a suitable site.
The thermometer should be placed under the tongue.
The patient's mouth should be closed.
The posterior sublingual pockets are perfused by a branch of the external carotid artery.
Oral temperature closely follows core temperature changes.

The rectal site reflects the deep visceral temperature, measured through the iliac artery and vein.
Rectal temperature is higher than other sites in a steady state.
This is likely due to low blood flow and high isolation in the area, resulting in less heat loss.
There's a 0.5°C difference between rectal and oral temperatures (rectal is higher).
Axillary temperature is +0.5°C.
Rectal temperature is -0.5°C.

The tympanic membrane shares its blood supply from the internal and external carotid arteries.
The area is relatively devoid of metabolic activity.

Measured by an infrared scanner on the forehead.
Temporal thermometers measure the heat from blood moving through the temporal artery.
A quick, non-invasive, and accurate method.

Tympanic Membrane Thermometer: Small handheld device with a sensor probe and a disposable probe cover connected to a battery-operated unit.
Chemical Thermometer: Used by patients at home. Disposable chemical single-use thermometers contain chemical dots which respond to body heat.
Temperature Sensitive Strips: Reusable plastic strips with heat-sensitive liquid crystals to measure body temperature. The strip is pressed onto the forehead until the colors stop changing (about 15 seconds). The strip is then removed and washed.