Evaluating temperature is essential
in the prehospital setting
By Joseph E. DiCorpo, BSc, MMSc, PA; Matthew Harris, MD
& Mark Merlin, DO, EMT-P, FACEP
The measurement of patient tempera- ture is, and has been, throughout the history of modern medicine, one of
the four core physiological measurements that
we collectively call “vital signs.”
Over the past decade we’ve added the mea-
surement of oxygen saturation (transcutaneous
pulse oximetry, or SpO2) as the fifth vital sign
and we hope that in the near future we’ll add
end-tidal carbon dioxide (EtCO2) measure-
ment as the sixth vital sign.
Our review and discussion in this article will
concentrate on the renewed importance, implications and technical measurement of a patient’s
body temperature, and explore how fever serves
as an important and concerning finding.
WHAT IS TEMPERATURE?
Temperature can best be defined as the tem-
perature of the body when measured by either
an infrared or conductive method. In terms
of relating temperature to more meaningful
physiological parameters, the parameter most
closely aligned to temperature is basal meta-
bolic rate (BMR).
BMR is essentially an estimate of how
much oxygen we consume, and therefore the
calories we burn, at any sustained activity level.
The higher our BMR, the higher our temperature, and vice versa.
Since we routinely measure temperature
at the skin surface, however, we have to take
into consideration physiological responses to
disease and injury, which can substantially
influence skin perfusion and thereby the measured temperature.
It’s important for emergency personnel to
be aware that a person’s normal body tempera-
ture may be vary anywhere from 0.5 degrees F
to 1.0 degrees F according to the time of day
and activity. ( Table 1, p. 33, indicates the nor-
mal body temperature mean and range for
adult males and females.)
Although all vital signs are an important part of your toolbox when you conduct
an objective patient assessment, measuring
and understanding a patient’s temperature
can provide you with important insight into
the patient’s clinical picture. Normothermia,
hyperthermia and even hypothermia are all
extremely relevant factors in your assessment.
In order to demonstrate this let’s review some
A 29-year-old female passes out in her office.
There’s no significant medical or surgical history. In addition to the current new onset syncope, she complains of bilateral low back pain.
She denies shortness of breath, but complains
of dizziness for the past few hours. She reportedly “passed out” when she stood up after being
seated at her desk for “a few hours.”
Temporal artery scan thermometers can be substantially influenced by sweat and/or moisture, and
therefore may not be reliable for field use.
Photo courtesy Kevin Watler/Polk County Fire Rescue