When it comes to taking one's temperature, rectal thermometers are definitely not a patient's first choice. Researchers found less invasive peripheral thermometers fail to provide clinically accurate body temperatures.
Led by intensive care physician Dr. Daniel Niven from the Peter Lougheed Center in Calgary, a team of doctors conducted an intensive review of various thermometer types covering 75 international studies. The combined studies covered over 8,600 patients including children and adults.
The team compared body temperatures taken using peripheral thermometers through the forehead, ear, armpit and mouth. These measurements were then compared to the body temperatures taken by more invasive instruments called central or rectal thermometers, which are placed inside the bladder or rectum. They found that temperatures taken with peripheral thermometers vary in accuracy by as much as 1.5 degrees.
"At extremes of body temperature, peripheral temperature measurements may be as much as 1 to 2 degrees higher or lower than actual body temperature," wrote Niven. "Peripheral thermometers therefore represent a poor screening tool for detecting temperature abnormalities."
In cases where doctors need to make vital clinical decisions, central thermometers are the gold standard. Conditions that involved infection risks should use more invasive instruments when taking the patients' temperature. In elderly patients with damaged immune systems, tumors and tissue disease, a low-grade fever could be an indication of infection, especially in patients who do not show typical early symptoms.
Niven noted that many Intensive Care Units (ICU) still rely on body temperatures taken by peripheral thermometers via the armpits. The researchers hope that the findings will help hospitals to switch to central thermometers especially in the ICU where measurements are vital and life-saving.
In children afflicted with minor illnesses like sore throat, cough and runny nose, many parents use thermometers on the armpits and forehead. Researchers found that body temperatures taken in the ear and mouth are more precise.
There are cases when central thermometers shouldn't be utilized. For instance, patients with neutropenia where neutrophils levels are low, calibrated tympanic membrane thermometers or electronic oral thermometers are the closest best alternatives. The findings were published on Nov. 17 in the Annals of Internal Medicine.
