How accurate is temporal artery temperature (TAT) measurement?

Accuracy of Temporal Artery Temperature Measurement

Temporal artery thermometers are not sufficiently accurate for clinical situations where precise temperature measurement is required and should not be relied upon when accurate temperature assessment is critical to diagnosis and management. 1

Hierarchy of Temperature Measurement Accuracy

Temperature measurement methods can be ranked in order of decreasing accuracy:

1. Gold standard methods (most accurate):

   • Pulmonary artery catheter thermistors
   • Bladder catheter thermistors
   • Esophageal balloon thermistors

2. Acceptable alternatives when invasive methods aren't available:

   • Oral temperature (in alert, cooperative patients)
   • Rectal temperature

3. Less reliable methods (not recommended when accuracy is critical):

   • Temporal artery thermometers
   • Tympanic membrane thermometers
   • Axillary measurements
   • Chemical dot thermometers

Evidence on Temporal Artery Thermometer Accuracy

The 2023 Society of Critical Care Medicine and Infectious Diseases Society of America guidelines specifically state that temporal artery thermometer estimates "have not been reliable" and "should not be relied on" 1. These devices:

• Demonstrate poor agreement with core temperature measurements
• Are influenced by environmental temperature and sweating
• Show significant variability in measurements

Research studies confirm these limitations:

• When compared to pulmonary artery temperature (gold standard), temporal artery measurements showed clinically significant differences (>0.9°F) in 25% of cases 2
• In febrile patients, temporal artery thermometers tend to underestimate temperature, with a mean difference of -0.90°C compared to bladder temperature 3
• The sensitivity for detecting fever (≥38.3°C) using temporal artery thermometry is only 0.26, though specificity is high at 0.99 3
• A meta-analysis found temporal artery thermometers had a pooled difference of -0.19°C with wide limits of agreement (-1.16 to 0.77°C) compared to reference methods 4

Clinical Implications

When to Use Temporal Artery Thermometers

Temporal artery thermometers should only be used:

• When more accurate methods are unavailable or contraindicated
• For screening purposes, not for definitive temperature assessment
• With awareness of their limitations, particularly in febrile patients

When NOT to Use Temporal Artery Thermometers

Avoid temporal artery thermometers in situations where:

• Precise temperature measurement is critical for diagnosis
• Management decisions depend on accurate fever detection
• The patient is critically ill and temperature monitoring is essential
• The patient has conditions that may affect skin perfusion

Practical Recommendations

1. In critical care settings, use central temperature monitoring methods (pulmonary artery, bladder, or esophageal thermistors) whenever these devices are already in place 1

2. For patients without central monitoring devices, use oral thermometry in alert, cooperative patients or rectal thermometry when oral measurement is not feasible 1

3. If using temporal artery thermometry due to lack of alternatives:

   • Recognize it may underestimate temperature in febrile patients
   • Consider using a lower threshold (e.g., 37.7°C instead of 38.0°C) for fever detection 5
   • Confirm abnormal readings with a more accurate method when possible

4. Document the site and method of temperature measurement in the patient's chart to ensure proper interpretation of values 1

Common Pitfalls

• Relying on temporal artery temperature alone for critical clinical decisions
• Failing to recognize that temporal artery thermometers may miss fevers due to low sensitivity
• Not accounting for environmental factors that can affect temporal artery readings
• Using temporal artery thermometers interchangeably with more accurate methods without recognizing the potential for significant measurement differences

In summary, while temporal artery thermometers offer convenience and non-invasiveness, their accuracy limitations make them unsuitable for situations where precise temperature measurement is needed for clinical decision-making.