Motivation: In the clinic, many patients come with "high fever" - one patient insisted that at home he consistently measured his temperature at 105.0 although we found his fever to be no higher than 100.0. What happened? I wonder now whether we were using the same measurement techniques. Talking to attendings, I have found that almost all favor or dislike one or more methods of temperature measurement. The following paper compares some commonly used measurement techniques of core body temperature to the gold standard - pulmonary artery catheter temperature measurement.
Paper: Accuracy and Precision of Noninvasive Temperature Measurement in Adult Intensive Care Patients. Lawson, L. et. al. Am. J. Crit. Care, 2007 (16): 485-496. http://ajcc.aacnjournals.org/cgi/content/abstract/16/5/485
Methodology: The authors collected temperature by pulmonary artery catheter (PAC), axillary, temporal artery, tympanic membrane, and oral techniques. The four external measurements and PAC temperature were collected within a minute of each other. Sequential temperature measurements using all techniques were taken three times at twenty minute intervals to analyze intra and inter-method variability and concordance.
Patient Selection: Sixty adults in ICU (40 male and 20 female) with cardiopulmonary disease and pulmonary artery catheter. Patients were excluded if they had oral pathology, head trauma, or not visible tympanic membrane.
Results:
PAC vs oral - On average, oral measurement underestimated PAC temperature by about 0.09°C (0.16°F). The precision (reproducibility) was 0.43°C (0.77°F). 19% of measurements were more than 0.5°C (0.9°F) different from PAC. Oxygen delivery via nasal cannula did not make a clinical difference in temperature measure, but intubated patients consistently had higher oral measurements.
PAC vs tympanic membrane - On average, tympanic membrane overestimated PAC temperature by 0.36°C (0.65°F). Precision was 0.56°C (1.0°F). 49% of measurements were more than 0.5°C (0.9°F) different from PAC.
PAC vs temporal artery - On average, temporal artery overestimated PAC temperature by 0.02°C (0.04°F). Precision was 0.47°C (0.85°F). Administration of vasopressor did not significantly alter concordance. 20% of measurements were more than 0.5°C (0.9°F) different from PAC.
PAC vs axillary - On average, axillary underestimated PAC temperature by 0.23°C (0.41°F). Precision was 0.44°C (0.79°F). 27% of measurements were more than 0.5°C (0.9°F) different from PAC.
Conclusion: On average, oral and temporal artery measurements are likely good estimates of core body temperature. Axillary temperature is probably next on the list followed last by tympanic membrane measure, in which 49% of measurements differed by more than 0.5°C from core body temperature. Another point to take home is that for any technique, changes of about 0.5°C - the precision level of almost all the techniques - can be explained simply by measurement variability. A final point is that even for the best non-invasive techniques like oral measurement, about 20% of the time, the temperature will be off by 0.5°C or higher.
Limitations: The major limitation in this paper is that only three patients were actually febrile. The concordance rates may differ with febrile patients. Also, all of the patients were in the ICU. Perhaps, in an outpatient setting, the results may vary. Finally, the measurements were taken by experienced ICU nurses. The accuracy and precision of measurements by medical students or by patients may be a whole different story.
Paper: Accuracy and Precision of Noninvasive Temperature Measurement in Adult Intensive Care Patients. Lawson, L. et. al. Am. J. Crit. Care, 2007 (16): 485-496. http://ajcc.aacnjournals.org/cgi/content/abstract/16/5/485
Methodology: The authors collected temperature by pulmonary artery catheter (PAC), axillary, temporal artery, tympanic membrane, and oral techniques. The four external measurements and PAC temperature were collected within a minute of each other. Sequential temperature measurements using all techniques were taken three times at twenty minute intervals to analyze intra and inter-method variability and concordance.
Patient Selection: Sixty adults in ICU (40 male and 20 female) with cardiopulmonary disease and pulmonary artery catheter. Patients were excluded if they had oral pathology, head trauma, or not visible tympanic membrane.
Results:
PAC vs oral - On average, oral measurement underestimated PAC temperature by about 0.09°C (0.16°F). The precision (reproducibility) was 0.43°C (0.77°F). 19% of measurements were more than 0.5°C (0.9°F) different from PAC. Oxygen delivery via nasal cannula did not make a clinical difference in temperature measure, but intubated patients consistently had higher oral measurements.
PAC vs tympanic membrane - On average, tympanic membrane overestimated PAC temperature by 0.36°C (0.65°F). Precision was 0.56°C (1.0°F). 49% of measurements were more than 0.5°C (0.9°F) different from PAC.
PAC vs temporal artery - On average, temporal artery overestimated PAC temperature by 0.02°C (0.04°F). Precision was 0.47°C (0.85°F). Administration of vasopressor did not significantly alter concordance. 20% of measurements were more than 0.5°C (0.9°F) different from PAC.
PAC vs axillary - On average, axillary underestimated PAC temperature by 0.23°C (0.41°F). Precision was 0.44°C (0.79°F). 27% of measurements were more than 0.5°C (0.9°F) different from PAC.
Conclusion: On average, oral and temporal artery measurements are likely good estimates of core body temperature. Axillary temperature is probably next on the list followed last by tympanic membrane measure, in which 49% of measurements differed by more than 0.5°C from core body temperature. Another point to take home is that for any technique, changes of about 0.5°C - the precision level of almost all the techniques - can be explained simply by measurement variability. A final point is that even for the best non-invasive techniques like oral measurement, about 20% of the time, the temperature will be off by 0.5°C or higher.
Limitations: The major limitation in this paper is that only three patients were actually febrile. The concordance rates may differ with febrile patients. Also, all of the patients were in the ICU. Perhaps, in an outpatient setting, the results may vary. Finally, the measurements were taken by experienced ICU nurses. The accuracy and precision of measurements by medical students or by patients may be a whole different story.
great posting shamik. i havent forgot about siriasis. im on a sub-i and finishing my personal statement. however, ive seen some amazing cases that i'll try to post when i have time. in fact, i saw a case of neurosyphilis last week! the csf and physical exam findings were pretty interesting. on that note, i wanted to let you know: if you have pts with interesting exam findings, there's a department of path photography. call them and they'll take high quality pictures and burn you a CD! anyway, hope alls well buddy!
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