PERIPHERAL thermometers may not be as accurate as central thermometers to measure body temperature, but can provide practical and efficient means to measure this vital sign when used consistently, says Professor John Wilson, president of the adult medicine division of the Royal Australasian College of Physicians.
Professor Wilson’s comments follow the publication of research in the Annals of Internal Medicine that showed most commonly used peripheral thermometers (tympanic membrane, temporal artery, axillary or oral) lacked accuracy when compared with central thermometers (pulmonary artery catheter, urinary bladder, oesophageal or rectal). (1)
The systematic review and meta-analysis of 75 studies, that included 8682 adults and children, found that at the extremes of body temperature, peripheral temperature measurements could be as much as 1‒2 degrees Celcius higher or lower than actual body temperature.
“Peripheral thermometers therefore represent a poor screening tool for detecting temperature abnormalities. In contrast, nonvascular central thermometers show excellent agreement with the gold standard, the pulmonary artery catheter, which confirms their clinical utility”, the researchers wrote.
“Rectal thermometers could be used for most of these patients, and bladder thermometers could be used for those requiring a bladder catheter.”
They warned that peripheral thermometers should not be used when accurate measurement of body temperature would influence clinical decisions.
Professor Wilson told MJA InSight that in most areas of medicine there were gold standards on which we would “ideally” base clinical decision-making. However, he said practical considerations, such as the most clinically applicable method and equipment availability, also weighed into these decisions.
“We would very much like to rely on central thermometers for decision making in medicine, but not everybody in their office has a pulmonary artery catheter, a rectal thermometer, a bladder temperature measurement [device], or an oesophageal thermometer. So one can only agree wholeheartedly with the authors that using peripheral thermometers — meaning not measuring core temperature in people — would be likely to be less accurate”, he said.
Professor Wilson said peripheral thermometers were practical and provided just one element in making a diagnosis.
“Peripheral thermometers have been used for a very long time and very few diagnostic errors are made by misinterpreting peripheral temperatures”, he said. “Experienced clinicians do not base their sole diagnosis on one measurement using a peripheral thermometer, but take into account the full constellation of history, examination and investigation findings.
“There is absolutely no problem with using peripheral thermometers to evaluate the cause of an illness, using the same thermometer, in the same location, with the same technique.”
Professor Wilson said issues with using different thermometers and different techniques in different locations in the hospital were more likely to skew temperature readings than the issues raised in the research article.
He also “strongly recommended” that clinicians remeasure a patient’s temperature themselves, using a familiar technique and reliable apparatus, if there were any uncertainties about the accuracy of a temperature reading.
Adjunct Professor Kylie Ward, CEO of the Australian College of Nursing, welcomed the extensive review of the data.
She said nurses would also always exercise their clinical judgement with patients.
“Temperature is one clinical indicator that nurses would draw upon in gathering clinical information, so it’s absolutely important to know that we are evidence based in our approach to patients and clinical care and medicine”, she said.
Professor Ward said invasive thermometers, such as central pulmonary, oesophageal, or rectal thermometers, also brought with them a degree of risk to the patient that doctors and nurses would take into consideration.
She said hospitals mostly used electronic oral and tympanic thermometers, which were both portable and affordable.
“Until there are more advances in technology that can give us … a more accurate measurement of temperature from a non-invasive perspective … what we’re using now is obviously the best that we’ve got.”
(Photo: chairoij / shutterstock)