7
Normal Body Temperature (BT)
Normal BT is not a single temperature,
but a range of temperatures influenced by
age, time of day, and measurement site.
General Rule of Thumb
Rectal temperature is
≈
2°F (1°C) higher
than axillary and
≈
1° F (0.5°C ) higher
than oral temperature.
1
Expect the Differences
Arterial temperature measurement (PA
Catheter, TA Thermometry) leads all
other methods in identifying fever or
defervescence, and is unaffected by
activities of daily living. Accordingly, it
will sometimes be different from your
present methods — but accurate.
Guidelines for Patient
Temperature Assessment
1. Normal TA Temperature:
On a
stable resting patient, TAT is
≈
0.8°F (
0.4°C ) higher than an optimum oral
temperature, and is about the same as
a rectal temperature. However, during
febrile episodes, the difference can be
much higher, mainly because of the
artifacts of oral and rectal sites.
2. Fever Definition:
Clinically, fever is
defined as a BT
≥
1.8°F (1°C) above
the mean standard deviation at the
site of recording.
2
A single oral temperature of
≥
101°F (38.3°C )
in the absence of obvious environmental causes
is usually considered fever. An oral temperature
of
≥
100.4°F (38.0°C) over at least 1 hour
indicates a fever state.
3
A single arterial temperature >101.8°F (38.8°C)
in the absence of obvious environmental causes
is usually considered fever. An arterial temperature
>101.2°F (38.4°C) over at least 1 hour
indicates a fever state.
While the above are recommended
guidelines, not all fevers require
laboratory tests, and clinical
assessment in concert with standard
hospital protocol for fever workups
should always prevail.
3. Oral Temperature Risks:
Oral
temperature can be clinically
misleading, and many febrile patients
can have a “normal” temperature.
4
Mouth breathing, tachypnea,
heated gases, and hot or cold fluids
can distort the reading, as can
intubation or inability of the patient to
cooperate. Accordingly, comparisons
with TA may not be reliable.
Normal Body Temperature Ranges at
Various Measurement Sites:
Arterial:
97.4-100.1°F
36.3-37.8°C
Oral:
96.6-99.5°F
35.9-37.5°C
Esophageal:
98.4-100.0°F
36.9-37.8°C
Rectal:
97.7-100.3°F
36.5-37.9°C
Axillary:
95.5-98.8°F
35.3-37.1°C
Oronasal:
96.6-99.0°
35.9-37.2°C
Clinical Information
