Yes, summer in Arizona is hot but we aren’t talking weather – hot. We are talking fever – hot, as in, is our ED temperature measurements correct? The scientist part of me wants accuracy, the caring part of me wants not to put things in peoples bum! So, is there a happy medium when it comes to detecting fever in the ED without doing a rectal on every patient? Let’s take a look at the literature.
Below I review three articles looking specifically at Temporal artery thermometers (TAT). There were some comparisons to axillary temperatures as well but this was not the focus. All the studies looked at both febrile and afebrile patients. Much of the evidence look at pediatric and geriatric patients who are unable to tell us if they feel febrile (not that most adults can tell either). I think the literature pretty conclusively shows that axillary temperatures are the pits (careful this might get worse). For Temporal Temps the findings were not much better. In summary TAT are not very accurate for representing core temps. One article summed it up best “Thus, it seems that TAT could replace tympanic thermometers with the caveat that both methods are inaccurate”1. From the studies overall, you get a +LR of 12 and a -LR of 0.3. That is if a patient is febrile according to the TAT then it is probably correct. However. if a patient is not febrile by TAT then they may still have a temp. So, what can we say? TAT are not very accurate. However, I still don’t think every patient needs a rectal temp. If I think a patient is febrile then I am probably just as correct as the TAT. If I really am worried I can get a rectal temp. So here is how I do it. If I see a patient has a temp (>38C) on the vitals by TAT then I am good. If a patient has an environmental exposure or altered I will get a rectal temp. If they are afebrile by TAT but feel warm or tachycardic then I’m pretty sure they have a temp. If they have unexplained tachycardia I work that up (sometimes just shared decision making with the patient) until I am comfortable that no emergent condition exists.
The details for the three articles are below.
The first article is by Brosinksi in “Comparison Of Temporal Artery Versus Rectal Temperature In Emergency…” 2. These authors looked at a single facility on a remote island (sounds nice). The enrolled 126 pediatric patients and 125 geriatric patients They included febrile and afebrile pediatric patients 3 years old and younger and geriatric patients aged 65 and older, all whom were unable to participate in an oral temperature assessment owing to their inability to follow commands, mouth breathing, respiratory distress, or facial/ oral trauma. They excluded patients with injuries or deformities at the temporal site or those with behavorial problems who may be disturbed by temporal measurement. Each patient underwent one rectal temp (RT) and 3 temporal artery temps (TAT) measurements – Thank god it wasn’t the other way around! For the pediatric group they found the false positive rate of predicting RT fever by TAT for pediatric patients is 14.7%, and the false negative rate is 9.8%, yielding sensitivity of 90%, and specificity of 85%. The overall accuracy was 87%. The 95% confidence interval (CI) for a reading on an individual patient was ± 2.36°. For the geriatric group they found the false positive rate of predicting RT fever by TAT to be 6.0% and false negative rate 25.9%, yielding sensitivity 74.1%, and specificity 94.0%. The overall accuracy is 85%. The CI for a reading on an individual patient was ± 2.97°.
The next article is by Forrest 3 and is entitled “Temporal artery and axillary thermometry comparison with rectal thermometry in children presenting to the ED”. They studied 85 children 1 day to 36 months with and without a fever and excluded active chemo, neutropenia or a child “in distress”. Using a standard cutoff for fever of a rectal temp of > 38.0 °C, the sensitivity and specificity for detecting fever were 11.5% and 100%, respectively for axillary. For TAT, the sensitivity and specificity for detecting fever were 61.5% and 93.3%, respectively. The mean temperature difference in the febrile group was >0.5 °C for TAT and >1.0 °C in axillary measurements.
The last article is a systematic review 1 that looked at TAT and compared it to a core temp. The primary outcome was measurement accuracy of the index test compared to a reference standard, expressed as pooled estimates of mean temperature difference. They pooled 37 included articles together to get 5026 study participants of which 1301 were adults and 3725 were children. The found a difference of −0.19°C (95% CI of −1.16 to 0.77°C). There was a trend towards larger differences from the reference for febrile patients, with an underestimation of the temperature. They found an overall Sn of 72% and a Specificity of 94%. This study made the best summary I could find: Our results indicate that TAT is not sufficiently accurate to replace one of the reference methods… Although inaccurate, the results are similar to those with tympanic thermometers…Thus, it seems that TAT could replace tympanic thermometers with the caveat that both methods are inaccurate.
- Geijer, H., Udumyan, R., Lohse, G. & Nilsagård, Y. Temperature measurements with a temporal scanner: systematic review and meta-analysis. BMJ Open 6, e009509 (2016).
- Brosinski, C., Valdez, S., Riddell, A. & Riffenburgh, R. H. Comparison of Temporal Artery Versus Rectal Temperature in Emergency Department Patients Who Are Unable to Participate in Oral Temperature Assessment. J Emerg Nurs 44, 57-63 (2018).
- Forrest, A. J. et al. Temporal artery and axillary thermometry comparison with rectal thermometry in children presenting to the ED. Am J Emerg Med 35, 1855-1858 (2017).