Chapter 2: Temperature

Methods of Measurement

Methods of measuring a client’s body temperature vary based on developmental age, cognitive functioning, level of consciousness, state of health, safety, and agency/unit policy. The healthcare provider chooses the best method after considering client safety, accuracy, and least invasiveness, all contingent on the client’s health and illness state. The most accurate way to measure core body temperature is an invasive method through a pulmonary artery catheter. This is only performed in a critical care area when constant measurements are required along with other life-saving interventions.

Methods of measurement include oral, axillary, tympanic, rectal, and dermal routes. It is best to engage in a discussion with the institution and the unit that you work in about what methods they use and why.

Tympanic routes are common in the adult population both in primary settings and acute settings.

Oral temperature can be taken with clients who can follow instructions, so this kind of measurement is common for clients over the age of four, or even younger children if they are cooperative. Usually with a child who is stable or in a routine situation (and the client is able to follow instructions – about age four), then, most likely you would do oral temperature. However, you would avoid an oral route with a confused client as you need to assess whether they have recently consumed hot or cold fluids. In these cases, you may take a tympanic or axillary; these routes are also preferable when a client is on oxygen delivered via a face mask (as mask that covers the nose and mouth) because this can alter the temperature.

Also, for children younger than four who are stable and in a routine situation, axillary temperature is commonly measured unless a more accurate reading is required. If you have a concern about the temperature, a rectal temperature is preferred in children.

Rectal temperature is an accurate way to measure body temperature (Mazerolle, Ganio, Casa, Vingren, & Klau, 2011) and particularly used in the pediatric population for accuracy and in acute situations. The rectal route is recommended by the Canadian Pediatric Society for children under two years of age (Leduc & Woods, 2017). However, rectal temperatures are commonly taken with children under three in several situations such as when in hospital, when in an isolette, and when the client is not stable or in acute situations. However, this method is not used on infants younger than thirty days or premature infants because of the risk of rectal tearing. If the rectal method is required, the procedure is generally only used by nurses and physicians.

Dermal routes are alternative methods of measurement that may be used in some agencies and practice areas. This method can involve holding the device and sliding it over the skin of the forehead and then down over the temporal artery in one motion. Dermal strips can also be placed on the forehead to measure skin temperature, but are not yet widely used, and the accuracy of this method has not yet been verified. More recently, there has been an increase in non-contact infrared thermometers particularly in the era of COVID-19 and other highly transmissible diseases. Depending on the type, these thermometers can be held at a short distance from the forehead or temporal area to measure temperature. Alternatively, some handheld thermal scanners that use an infrared camera can be held at a greater distance to screen large masses of people. Please refer to the manufacturer’s suggested reference range for non-contact infrared thermometers and thermal scanners.

Test Yourself!

While watching the interactive video on measuring temperature with a non-contact infrared thermometer, apply your knowledge and critical thinking skills to answer the questions throughout the video. Please note: there is no sound in this video.



Points to Consider

The accuracy of measurements is most often influenced by the healthcare provider’s adherence to the correct technique.

The following pages detail the normal temperature ranges and techniques associated with oral, axillary, tympanic, and rectal temperature methods.


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Vital Sign Measurement Across the Lifespan – 2nd Canadian edition Copyright © 2018 by Ryerson University is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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