FAQ [Health Devices Sep-Oct 1998;27(9-10):368-9]
Question: Why do we get inaccurate
and inconsistent patient temperature measurements when using our ear
thermometers? Should we use a different brand?
Answer: Hospital Grade ear
thermometers (frequently referred to as tympanic thermometers) are generally
very accurate instruments. Most likely, your problems are not related to the
thermometers themselves—rather, they are likely the result of an
inadequate understanding of the limitations of ear thermometry. Thus, it is
unlikely that these problems will be resolved simply by changing
Ear temperature can vary greatly because
of environmental factors (e.g., if the patient's ear has not warmed up from
being outside in cold weather) and because of variations in patient ear anatomy.
Consequently, a single ear-temperature measurement will not reliably establish
the presence or absence of a fever. ECRI discourages the use of ear thermometers
to make treatment decisions based on a single measurement. We also discourage
the assessment of ear-thermometer readings using protocols and target values
that have been established for other temperature-measurement sites.
ECRI believes that ear thermometers
should be used only for tracking or trending of patient temperature status. Even
this use can be compromised by inconsistent user technique (i.e., failing to
position the thermometer at the same depth and angle in the ear canal for each
measurement). Inconsistency will result in significantly varied measurements
from patients whose temperature status is in fact unchanged. Achieving
compliance with standard technique requires that the staff understand the
importance of consistency and that any differences of opinion about the best
technique be resolved.
To avoid diagnosis errors and measurement
inconsistency, ECRI recommends the following:
- Use only one model of ear
thermometer in any given institution.
- Set all thermometers to the same
mode or "offset."
- Ensure that all users employ a
- Record measurements in charts
as "Ear Temperature" (or an appropriate abbreviation), with an
indication of which ear—right or left—the measurement was taken
Thermometers, Electronic, Infrared, Ear