11.11: Equipments Used to Measure Body Temperature
Body temperature can be assessed using various devices and measured in Celsius or Fahrenheit.
Glass-bulb Thermometer:
Glass-bulb thermometers are hollow glass tubes with a bulb tip containing liquid such as ethanol or mercury. Historically, glass bulb mercury thermometers were the standard device to measure body temperature. Today, mercury thermometers are prohibited in many countries due to the hazardous effects of mercury and the risk of exposure if the glass bulb breaks. In general, glass-bulb thermometers pose a risk of unintended injury to patients if the glass breaks.
Electronic and Digital Thermometer:
Electronic and digital thermometers are designed to assess oral, rectal, or axillary body temperature in 1 to 60 seconds. The electronic thermometer comprises a rechargeable battery-powered display unit, a temperature-processing probe covered by a disposable probe cover, and a thin wire cord. Some models have separate, unbreakable, reusable probes with single-use disposable covers for oral and rectal usage. These battery-powered devices display a numerical temperature. In some, the most recent measurements have a 60-second pulse timer that automatically converts temperature readings from Fahrenheit to Celsius.
Tympanic Membrane Thermometer:
Tympanic membrane thermometers are an otoscope-like speculum that uses infrared sensors to measure heat emitted by the tympanic membrane. The probe is encased with a probe cover and securely placed into the ear canal to close the opening. Depending on the product, the reading takes between 1 and 3 seconds.
Disposable single-use Thermometers or Chemical Dot Thermometers:
Disposable single-use or chemical dot thermometers are unbreakable and detect the patient's temperature in seconds. Since they are only used once, single-use thermometers eliminate the risk of cross-infection. This is ideal for use with patients on isolation precautions.
Chemical dot thermometers are temperature-sensitive patches or tape, which are placed on the stomach or forehead, that change color to reflect the temperature. The Celsius version has 50 dots, each reflecting a 0.1° C temperature increase from 35.5° C to 40.4° C. The Fahrenheit version features 45 dots with 0.2° F variations and a temperature range of 96°F to 104.8° F. These thermometers can be used on children. If the color of the tape or patch indicates abnormal temperature, a more traditional type of thermometer should be used to verify the temperature reading.
Temporal Artery Thermometer:
Temporal artery thermometers use the heat radiated by the skin above the temporal artery to determine body temperature. These devices are battery-powered and have a temperature display.
