Body Temperature - What You've Been Taught is Wrong! (Strong Exam)

[Music] hello today I'll be discussing the assessment of body temperature within the context of the physical exam the method of checking the temperature may seem very simple but it's worth considering the specific technology behind the thermometer used in adults excluding Critical Care units which use more invasive technology to measure Central temperature there are otherwise four basic styles of thermometer which measure so-called peripheral temperatures in my experience as an inpatient doctor for adults the most common one is one that uses an electronic thermister to measure either oral or axillary temperature then there are three different style or thermometer that used infrared light one that is swept across the forehead or placed against the temporal artery one that is placed inside the ear to measure the temperature of the tanic membrane and a non- contct one which measures forehead temperature and which became particularly popular during the co pandemic there is actually a good amount of data investigating the accuracy of all these thermometer types including specific Brands the bottom line when compared to measures of central body temperature none of them are very good one recent met analysis in the respected anals of internal medicine summarized their findings as peripheral thermometers do not have clinically acceptable accuracy and should not be used when accurate measurement of body temperature will influence clinical decisions considering that metaanalysis included the same basic style of oral thermometers that we use in the hospital hospital that's more than a little disconcerting yet at the same time there are multiple studies claiming that peripheral thermometers such as temporal artery and tanic infrared thermometers are relatively accurate certainly the companies which make such thermometers advertise them as so the Welsh Allen short temp devices our Hospital uses it claims an accuracy to within 0.2 de F why this discrep well it's because these studies of peripheral thermometers use other peripheral thermometers as the gold standard to which they are being compared for example in this 2021 study of seven commercially available peripheral thermometers the gold standard was the same Welsh Allen short temp device in my hospital so yeah the inexpensive consumer grade devices were similar to the professional grade one but that only begs the question of how Welsh Allen determined their Prof professional grade devices accuracy and the answer to that is I have no idea there are no relevant papers in the medical literature there is nothing to be found on the website of the company that owns the Welch Allen brand I can't find any documentation on the website for the FDA which regulates such medical devices and the manufacturer has not responded to my request for additional information so it's my strong but unproven suspicion that the discrepancy between companies claiming their thermometers are accurate and scientists who State otherwise is that they are comparing apples to oranges a given model of a peripheral thermometer may be accurate at measuring peripheral temperature but peripheral temperature may not correlate well with Central core temperature this only begets yet another layer of questions for example do we know for a fact that Central temperature correlates better with diseases characterized by fever than does peripheral temperature now it intuitively seems like Central temperature should be more reflective of pathology but as far as I can tell that hasn't actually been established either in general or in any one specific disease but the assessment of temperature gets even more complicated when we try to answer the questions of what the normal range is and what threshold we should use to label a temperature as a fever it is a supposed fact that along the way every person seems to learn the normal body temperature is 98.6 degrees Fahrenheit or 37.0 degre C but that is just another myth like all myths this one started somewhere and that somewhere was the 19th century German physician Carl Reinhold August wunderlick wunderlick was the first physician to seriously study human body temperature and he is generally credited as the first promote the idea that fevers were a symptom of disease and should not be framed as the disease itself his study of temperatures included recording 1 million axillary temperature readings from 25,000 individuals spanning many years based on those readings he identified 37.0 de C or 98.6 de f as the mean temperature in adults this work of wonderlick is is where the 98.6 Dee myth comes from but there are four big problems first vunder never said that 98.6 was the single normal temperature just that it was the mean or the average around which people's temperatures were normally distributed second these were measurements taken in patients who were in variable Health life expectancy in Europe during this time was about 40 years how many of his study subjects were walking around with occult cancers periodontal infections or indolent tuberculosis all diseases which increase body temperature there is convincing evidence that average human body temperature has actually dropped over the last 150 years which is hypothesized to be due to a lower prevalence of infectious disease third we now know and possibly wonderlick knew this as well that his preferred site of measuring temperature in the axilla in general tends to measure a lower temperature than oral rectal and the true core body temperature and last we also now know that at least one of Wonder's thermometers appears to have been dramatically miscalibrated measuring 1 and A2 to 2° C warmer than it should that's an error of 3 degrees Fahrenheit we know this because one of his original mercury thermometers was tracked down in Philadelphia's mut Museum and was tested against both modern instruments and against other 19th century thermometers of similar design wonderlick presumably used more than one thermometer for his million temperature readings so we shouldn't make a generalized conclusion about the amount or direction of his inaccuracies just that substantial inaccuracies were present one contemporary attempt to determine normal body temperature found an average oral temperature of 97.5 F or 36.4 C while another found averages of 97.9 F or 36.6 C aside from 98.6 being too high of an average other issues with defining a normal range for temperature include the normal dial variation in body temperature which temperature is lowest in the early morning and highest in the late afternoon with an estimated difference of 0 0.9 F and 0.5 C temperature is also slightly higher in females than males and in those who menstrate temperature varies depending on the phase of the menstrual cycle with a higher temperature in the weeks after ovulation and before the onset of menstrual bleeding this effect is believed to be driven by levels of the hormone progesterone if this all wasn't complicated enough normal body temperature drops in advanced age while individuals with curosis hypothyroidism chronic kidney disease and heart failure all typically have body temperatures slightly lower than healthy individuals even environmental factors such as the ambient temperature season and the due Point May influence body temperature in summary average body temperature across all people is lower than what is commonly believed and it varies between individuals and varies across time within the same individual defining one single normal range that applies to everyone doesn't make any sense unfortunately from the Practical side of medicine we do need to have some idea of when a temperature in a given patient is high enough to be labeled a fever in the United States it's very common for that cuto off to be 1004 fenhe but this cut off is also derived directly from Wonder Lick's original lawed data the optimal solution to this conundrum might be using the electronic medical record to automatically adjust a patient's temperature based on their sex age and time of day to see if that value crossed a fever threshold or alternatively for a patient with many temperature data points a fever could be defined as a temperature which exceeds some amount beyond that individual patient's normal range but to the best of my knowledge neither of those potential Solutions or any other solution for that matter matter have been tried critically this is not just semantics the presence or absence of a fever can significantly alter the workup of a patient it can extend or shorten hospital stays and the presence of a fever is part of the diagnostic criteria for many different diseases it is not a trivial question and yet modern medicine does not have an answer however if in a particular patient using an inherently inaccurate thermometer and the arbitrary definition of fever of your choice you determine a fever to be present what are some general potential ideologies ideologies of fever can be placed into one of four broad categories infections autoimmune and autoinflammatory disease cancer and miscellaneous which includes things like heat stroke pulmonary embolism and medication side effect while a fever is usually just one of a number number of symptoms that develops in a patient at the same time such as a patient with pneumonia Who develops shorteners of breath cough and a fever a fever can also be the sole manifestation of disease as experienced by the patient classic diseases which present with only a persistent fever include things like Subacute endocarditis extrapulmonary tuberculosis osteomyelitis and discitis Lymphoma and an otherwise uncommon condition called adult onset Stills disease when the underlying cause of the persistent fever remains undetermined despite a reasonable thorough initial workup the patient may be labeled as having a so-called fever of Unknown Origin it's uncommon but body temperatures can also be unusually low a condition known as hypothermia ideologies of hypothermia include exposure to a cold environment and severe sepsis in which it's considered to be a particularly poor prognostic sign hypothermia can also be due to the A4 mentioned chronic illnesses of curosis hypothyroidism chronic kidney disease and heart failure regarding pitfalls and mistakes with measuring the temperature there are really two both of which I've already mentioned first is being too trusting of the accuracy of a thermometer unless the thermometer is in the patient's rectum their bladder or their pulmonary artery it's not as accurate as you think it is the second is being overly dogmatic with the cut off for a fever using the same temperature in all patients at all times relevant to this a common situation is when a patient presents with some acute illness a temperature is measured and found to be something like 99.8 fahit and the clinician says that's not a true fever yet the patient responds that they run low and therefore it's a fever for them I've heard clinicians scoff at this response from patient they'll claim that some patients temperatures don't naturally run low but they do this doesn't mean that every patient who reports that a near normal temperature is a fever for them is correct but you should also not reflexively blow off a patient who states [Music] this

Channel: Strong Medicine

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Id: g0_32Np8IxY

Length: 13min 29sec (809 seconds)

Published: Mon Jan 15 2024