Temperature examination

Core temperature

Temperature examination in the heart, using a catheter, is the traditional gold standard measurement used to estimate core temperature (oral temperature is affected by hot or cold drinks, ambient temperature fluctuations as well as mouth-breathing). Since catheters are highly invasive, the generally accepted alternative for measuring core body temperature is through rectal measurements. Rectal temperature is expected to be approximately 1 °F (0.56 °C) higher than an oral temperature taken on the same person at the same time. Ear thermometers measure temperature from the tympanic membrane using infrared sensors and also aim to measure core body temperature, since the blood supply of this membrane is directly shared with the brain. However, this method of measuring body temperature is not as accurate as rectal measurement and has a low sensitivity for fever, failing to determine three or four out of every ten fever measurements in children. Ear temperature measurement may be acceptable for observing trends in body temperature but is less useful in consistently identifying and diagnosing fever.