Question about digital oral thermometers

[Chribri]

My assessments teacher said last week that any error in using a digital thermometer will only result in a lower reading, that the reading will go only as high as it's environment and rechecking a high reading is unnecessary unless you think it will go higher.

last week I had a Pt in clinicals with a temp reading of 99.6. I know this is not technically febrile but she was an older woman and this was definitely high for her. I told my nurse this and she decided to recheck it, during which the patient was talking to her sister and the reading was back down in the 98's.

I told the staff nurse what my instructor had taught us about high readings and also that I thought her reading may have been affected by the patients talking through clenched teeth but she seemed to think it was not enough to effect her reading.

Was my instructor wrong about not getting false highs? Do you expect and accept a certain amount of interference from the patient when taking oral temps? Should I have just not said anything (the nurse seemed to take it kinda personally).

[xtxrn, ASN, RN]

Is this a thermometer as part of a dynamap?

Or a puny thing that is about 3/4 inch wide, and 4 1/2 inches long in a plastic case? (shape can vary- but bottom line is it's not connected to anything else).

[Chribri]

The hospital I'm at uses the smaller hand held units, they are mounted onto the side of the dynamaps.

[nurseprnRN, BSN, RN]

the answer to this is based on the physics of how electronic thermometers work. short answer is that if an electronic thermometer isn't working, it doesn't give high- or low- readings, it doesn't give you any reading. so at the time those two measurements were made, you can assume they were accurate.

it is perfectly possible for your patient to have had a higher reading earlier and then, perhaps unbeknownst to you, have had a nice chocolate milkshake or a cup of ice water in the meantime. or maybe a hot cuppa tea before you took her temp in the first place.

as a bit of trivia information, did you know that the idea of "98.6ºf is the normal oral temperature" dogma traces back to a german physiologist in the late 19th century, when oral mercury clinical thermometers were first available? he took the temps of >900 people and averaged them, and then with the rigid precision typical of his era and culture, declared the temperature. of course not everyone can have the same temperature-- that's ludicrous, isn't it?

actually, the blood in your body is at different temperatures depending on where it is at the moment. since the metabolic rate of kidneys is really high, renal venous temp is higher than, say, the temp of the blood coming back from your chilly feet or fingers. the physiologists take pulmonary artery blood temp as the body temp, because it's where all the blood from all the parts is well and truly mixed, thus an average temp of that body. we measure pa blood temp all the time in the icu with swan-ganz pa catheters with little temp sensors on the end, but most of us have to make due with more easily-accessible measurements. there's a whole body of work comparing various temp measuring sites to pa temps in an attempt to get the best correlation, and the best gadgetry to use to measure them.

good spot on knowing that 99.6ºf can be febrile for some people, and having assessed that hers was normally lower than average and should be rechecked.