Unreliability of the infrared tympanic thermometer in clinical practice: a comparative study with oral mercury and oral electronic thermometers

BACKGROUND: This study was designed to determine the magnitude and frequency of measurement errors with infrared tympanic thermometers in the clinical setting. METHODS: In a convenience sample of 137 adult inpatients, we compared body temperatures measured by a Diatek 9000 Infrared Aural Thermometer and an IVAC 2090 CoreCheck Tympanic Thermometer between themselves, in right versus left ears, and against concurrently measured oral temperatures using both an electronic thermoprobe and conventional glass mercury thermometer. RESULTS: There was a significant between-brand difference of 0.6 degrees C (IVAC 相似文献   

Infrared temperature measurement in the ear canal with the DIATEK 9000 Instatemp and the DIATEK 9000 Thermoguide. Comparison with methods of temperature measurement in other body parts

Temperature of the tympanic membrane is recommended as a "gold standard" of core-temperature recording. However, use of temperature probes in the auditory canal may lead to damage of tympanic membrane. Temperature measurement in the auditory canal with infrared thermometry does not pose this risk. Furthermore it is easy to perform and not very time-consuming. For this reason infrared thermometry of the auditory canal is becoming increasingly popular in clinical practice. We evaluated two infrared thermometers-the Diatek 9000 Thermoguide and the Diatek 9000 Instatemp-regarding factors influencing agreement with conventional tympanic temperature measurement and other core-temperature recording sites. In addition, we systematically evaluated user dependent factors that influence the agreement with the tympanic temperature. MATERIALS AND METHODS: In 20 volunteers we evaluated the influence of three factors: duration of the devices in the auditory canal before taking temperature (0 or 5 s), interval between two following recordings (30, 60, 90, 120, 180 s) and positioning of the grip relative to the auditory-canal axis (0, 60, 180 and 270 degrees). Agreement with tympanic contact probes (Mon-a-therm tympanic) in the contralateral ear was investigated in 100 postoperative patients. Comparative readings with rectal (YSI series 400) and esophageal (Mon-a-therm esophageal stethoscope with temperature sensor) probes were done in 100 patients in the ICU. The method of Bland and Altman was taken for comparison. RESULTS: Shortening of the interval between two consecutive readings led to increasing differences between the two measurements with the second reading decreasing. A similar effect was seen when positioning the infrared thermometers in the auditory canal before taking temperatures: after 5 s the recorded temperatures were significantly lower than temperature recordings taken immediately. Rotation of the devices out of the telephone handle position led to increasing lack of agreement between infrared thermometry and contact probes. Mean differences between infrared thermometry (Instatemp and Thermoguide, CAL-Mode) and tympanic probes were -0.41 +/- 0.67 degree C (2 SD) and -0.43 +/- 0.70 degree C, respectively. Mean differences between the Thermoquide (Rectal-Mode) and rectal probe were -0.19 +/- 0.72 degree C, and between the Thermoguide (Core Mode) and esophageal probe -0.13 +/- 0.74 degree C. DISCUSSION: Although easy to use, infrared thermometry requires careful handling. To obtain optimal recordings, the time between two consecutive readings should not be less than two min. Recordings should be taken immediately after positioning the devices in the auditory canal. Best results are obtained in the 60 degrees position with the grip of the devices following the ramus mandibulae (telephone handle position). The lower readings of infrared thermometry compared with tympanic contact probes indicate that the readings obtained represent the temperature of the auditory canal rather than of the tympanic membrane itself. To compensate for underestimation of core temperature by infrared thermometry, the results obtained are corrected and transferred into core-equivalent temperatures. This data correction reduces mean differences between infrared recordings and traditional core-temperature monitoring, but leaves limits of agreement between the two methods uninfluenced.     

Modern electronic and chemical thermometers used in the axilla are inaccurate

Rectal and axillary temperatures were measured simultaneously in 83 children using three different thermometer devices providing 166 pairs of results. In the first series consisting of 22 febrile children (44 measurements) and 20 afebrile children (40 measurements), the rectal mercury measurement was compared to an axillary mercury and axillary Tempa-DOT thermometer. The axillary mercury had sensitivity of 14/22 (64%) and specificity of 20/20 (100%) while the Tempa-DOT had sensitivity of 15/22 (68%) and specificity of 19/20 (95%). In the second series comprising 21 febrile children (42 measurements) and 20 afebrile children (40 measurements) the axillary mercury had sensitivity of 11/21 (52%) and specificity of 20/20 (100%) while the electronic thermometer had sensitivity of 10/21 (48%) and specificity of 20/20 (100%). Regardless of the thermometer used, the axilla is a poor alternative to rectal measurements in the diagnosis of fever. CONCLUSION: Mercury-free thermometers, when used in the axilla are as poor alternatives to rectal measurements as mercury-in-glass thermometers.     

A difference of 5 degrees C between ear and rectal temperatures in a febrile patient

A 4-year-old boy with a history of seizures triggered by fever presented at an emergency department (ED) with tachycardia, skin vasoconstriction, and a rectal temperature of 42.2 degrees C. However, his ear temperature (as repeatedly measured in two ears, by two experienced nurses, and with two infrared thermometers) was between 36.4 degrees C and 37.6 degrees C. Antipyretic therapy resulted in skin vasodilation, a rapid decrease of rectal temperature, restoration of heart rate, and disappearance of the difference between the two temperatures. Seizures did not occur. This case shows that infrared ear thermometry cannot be recommended in EDs as the procedure of choice for detecting fever in small children, especially when they are vasoconstricted.     

Agreement between rectal and tympanic membrane temperatures in marathon runners

STUDY OBJECTIVE: To determine the agreement between rectal temperature and infrared tympanic membrane temperatures in marathon runners presenting to a field hospital at the finish line. METHODS: The subjects of this prospective, blinded, controlled study were runners 18 years or older who were triaged to the acute care medical area at the finish line for suspected hypothermia, hyperthermia, dehydration, or altered mental status. Rectal and tympanic temperatures were measured simultaneously in all subjects for whom rectal temperature measurement had been deemed necessary and recorded on separate data cards. RESULTS: Of the 239 runners treated in the acute care medical area, 37 required rectal temperature measurement and were enrolled in the study. The mean rectal temperature was 38.45 degrees +/- 1.20 degrees C (range, 35.9 degrees to 41.5 degrees C). The mean tympanic membrane temperature was 37.81 degrees +/- 95 degrees C (range, 36.3 degrees to 40.4 degrees C). Pearson's correlation coefficient revealed a moderate correlation (r = .6902, P = .00023). The mean temperature difference between the two thermometers, mean rectal minus mean tympanic membrane, was .64 degrees C (95% confidence interval, .35 degrees to .93 degrees C). Sixty-Two percent of the tympanic membrane readings were within 1 degree C of their rectal counterparts. Agreement ranged from 1.16 degrees (+2 SD) to -2.95 degrees (-2 SD). The 95% confidence interval was 1.67 degrees to -2.95 degrees C. CONCLUSION: We were able to demonstrate only a moderate correlation between the two thermometer readings, with a wide spread between the limits of agreement. This spread could be clinically significant and therefore limits the usefulness of tympanic temperature in the marathon race setting. Because of the potentially large and clinically significant differences in rectal and tympanic temperatures and the limitations inherent in our study, we cannot endorse the use of tympanic temperature in the setting of a marathon event.     

Are electronic thermometry techniques suitable alternatives to traditional mercury in glass thermometry techniques in the paediatric setting?

Three thermometers, mercury in glass, Becton-Dickinson digital and IVAC tympanic membrane thermometer, were compared. The study was designed to test the null hypothesis that there is no difference between the thermometer recordings, meaning that electronic thermometry is a suitable alternative to traditional mercury in glass thermometry. Children aged between 0 and 15 years old were entered into the study, n = 114. Standard procedures were used throughout the study to minimize the risk of errors in the data collection and technical errors were recorded. The data were analysed using graphical techniques described by Bland and Altman. The differences between the temperature recordings were plotted against their mean (the estimated true value), with the bias and limits of agreement (2 standard deviations from the mean) calculated for the mercury in glass/digital, mercury in glass/tympanic and digital/tympanic temperature recordings. The range of temperatures were 35.1 degrees C-38.5 degrees C, with a mean of 36.85 degrees C for the mercury in glass thermometer, 36.8 degrees C for the digital thermometer and 36.65 degrees C for the tympanic thermometer. The bias for each comparison was 0.36 degrees C, 0.21 degrees C and 0.17 degrees C and the limits of agreement were wide, -0.516 degrees C to 1.234 degrees C, -0.84 degrees C to 1.252 degrees C and -0.940C to 1.244 degrees C for the mercury in glass/digital, mercury in glass/tympanic and digital/ tympanic recordings respectively. A difference of 0.2 degrees C is usually accepted for clinical practice, therefore the null hypothesis was rejected.     

The ear thermometer; not a good replacement for the rectal thermometer

OBJECTIVE: To compare the measurements of body temperature with the tympanic infrared thermometer and the digital rectal thermometer. DESIGN: Prospective, comparative. SETTING: Beatrix Hospital, Gorinchem, the Netherlands. PATIENTS AND METHODS: A total of 2057 almost simultaneous measurements of rectal and tympanic temperature were performed in 164 patients in 9 different wards. RESULTS: The mean difference between the two methods was 0.45 degree C with a standard deviation of 0.57 degree C. The tympanic temperature was lower than the rectal temperature. The differences ranged from -1.5 to 3.6 degrees C. The correlation coefficient was 0.69. If a rectal temperature > 37.8 degrees C was applied as the criterion of fever, the diagnosis was not made in 175/291 measuring moments (60%) with the tympanic thermometer. If a tympanic temperature > 37.8 degrees C was applied as the criterion of fever, the rectal thermometer failed to show fever in 16/132 measuring moments (12%). CONCLUSION: The low sensitivity of the tympanic measurement to establish fever renders the tympanic infrared thermometer unsuitable for use as a fever thermometer.     

Military medical subjects in the research of Academician P. K. Anokhin]

OBJECTIVE: To compare infrared thermometry with rectal thermometry as a method of assessing core body temperature in dogs and to assess the effect of otitis externa on external ear canal temperature (EECT). DESIGN: Prospective study. ANIMALS: 650 dogs without history or clinical signs of otitis externa and 85 dogs with recurrent or chronic otitis externa. PROCEDURE: Rectal temperature was measured, using a mercury thermometer. External ear canal temperature was measured, using an infrared tympanic thermometer. RESULTS: Measurements of body temperature at the 2 sites did not agree. Sensitivity and specificity of infrared thermometry in detecting fever, as determined by rectal thermometry, were 69.7 and 84.6%, respectively. Use of methods to predict rectal temperature from EECT did not improve the accuracy of infrared thermometry. Otitis externa significantly influenced EECT. CLINICAL IMPLICATIONS: Use of infrared thermometry as a replacement for rectal thermometry in assessing core body temperature in dogs was unsatisfactory. The 2 methods for measuring body temperature were not interchangeable in dogs.     

Congenital nystagmus image motion: influence on visual acuity at different luminances

This research study was undertaken to examine the relationship between pulmonary artery blood temperature (regarded as the 'gold standard' measurement for core body temperature), axilla temperature using the Tempa.DOT Ax chemical thermometer and tympanic membrane temperature using the Diatek 9000 InstaTemp thermometer. Sixty adult intensive care patients had their temperatures monitored. A single set of five simultaneous temperatures, i.e. left and right axilla, left and right tympanic membrane (TM), and pulmonary artery (PA) blood were recorded. The mean difference between left and right TM temperatures was 0.58 degree C, and although both were moderately well correlated with PA temperature (r = 0.63 and 0.78, respectively) the mean differences between the two sites were clinically significant (0.85 degree C and 0.94 degree C, respectively). The range of differences between the sites was significant. Plotting limits of agreement showed that both left and right TM temperatures may be up to 1.2 degrees C above or 1.3 degrees C below PA blood temperature: a clinically unacceptable range. In particular, large temperature differences were recorded when patients were lying with one side of their head to a pillow. Fan therapy directed to the head was not found to affect these differences significantly. The mean difference between left and right axilla temperatures was 0.36 degree C, and although both were modestly correlated with PA temperature (r = 0.48 and 0.53, respectively) the mean differences between the two sites were clinically significant (0.47 degree C and 0.50 degree C, respectively). The range of differences between the sites was particularly significant. Plotting limits of agreement showed that both left and right axilla temperatures may be up to 1.2 degrees C above or 1.6 degrees C below PA blood temperature: a clinically unacceptable range. Because the range of temperature differences found between PA blood and the other sites was so great, it is concluded that neither the chemical axilla thermometer nor the tympanic membrane thermometer used in this study are clinically reliable tools for adult intensive care patients.     

Desflurane reduces the febrile response to administration of interleukin-2

BACKGROUND: Intraoperative fever is relatively rare considering how often pyrogenic causes are likely to be present and how common fever is postoperatively. This low incidence suggests that general anesthesia per se inhibits the normal response to pyrogenic stimulation. The authors therefore tested the hypothesis that desflurane-induced anesthesia produces a dose-dependent inhibition of the febrile response. METHODS: Eight volunteers were studied, each on 3 study days. Each was given an intravenous injection of 50,000 IU/ kg of interleukin-2 (elapsed time, 0 h), followed 2 h later by 100,000 IU/kg. One hour after the second dose, the volunteers were assigned randomly to three doses of desflurane to induce anesthesia: (1) 0.0 minimum alveolar concentration (MAC; control), (2) 0.6 MAC, and (3) 1.0 MAC. Anesthesia continued for 5 h. Core temperatures were recorded from the tympanic membrane. Thermoregulatory vasoconstriction was evaluated using forearm-minus-fingertip skin temperature gradients; shivering was evaluated with electromyography. Integrated and peak temperatures during anesthesia were compared with repeated-measures analysis of variance and Scheffé's F tests. RESULTS: Values are presented as mean +/- SD. Desflurane reduced the integrated (area under the curve) febrile response to pyrogen, from 7.7 +/- 2.0 degrees C x h on the control day to 2.1 +/- 2.3 degrees C x h during 0.6 MAC and to -1.4 +/- 3.1 degrees C x h during 1.0 MAC desflurane-induced anesthesia. Peak core temperature (elapsed time, 5-8 h) decreased in a dose-dependent fashion: 38.6 +/- 0.5 degrees C on the control day, 37.7 +/- 0.7 degrees C during 0.6 MAC and 37.2 +/- 1.0 degrees C during 1.0 MAC desflurane anesthesia. Rising core temperature was always associated with fingertip vasoconstriction and often with shivering. CONCLUSIONS: Desflurane-induced anesthesia produced a dose-dependent decrease in integrated and peak core temperatures after administration of pyrogen, with 1.0 MAC essentially obliterating fever. Anesthetic-induced inhibition of the pyrogenic response is therefore one reason that fever is an inconsistent clinical response to inflammation during surgery.     

Do amoebic liver abscesses start as large lesions? Case report of an evolving amoebic liver abscess

Paired tympanic membrane and rectal temperatures were compared for 103 female fallow deer (Dama dama) after short-term anesthesia to determine if tympanic temperature was a reliable indicator of hyperthermia associated with handling stress. Each deer was restrained in a drop-floor chute, anesthetized by i.v. injection of xylazine hydrochloride and ketamine hydrochloride, and removed from the chute. After a short procedure was completed, i.m. antibiotics and i.v. yohimbine hydrochloride were given to each deer. Temperature measurements were obtained during recovery from anesthesia, approximately 10 min after initial restraint. Mean tympanic temperature (38.6 degrees C +/- 0.7 degrees C; range 37.4-40.8 degrees C) was significantly lower than mean rectal temperature (40.1 degrees C +/- 0.8 degrees C; range 37.5-42.0 degrees C) [corrected]. One animal had rectal and tympanic temperatures of 42.0 degrees C and 40.8 degrees C, respectively, but regained normal body temperature after cooling measures were applied. Tympanic membrane temperature measurement may provide a method for evaluation of body temperature by separating retained body heat caused by exertion from critical elevations in core body temperature associated with clinical disease or capture stress.     

Supralingual temperatures compared to tympanic and rectal temperatures

OBJECTIVE: To evaluate the validity, reliability, sensitivity, and specificity of the PaciTemp supralingual digital pacifier thermometer as compared to the Thermoscan Instant tympanic and glass-mercury rectal thermometers. METHOD: Eighty-one children under the age of 2 years had temperatures taken sequentially at three body sites: supralingual, tympanic, and rectal. Corrections were calculated between the readings of the three types of thermometers. Percentage of agreement was done to examine sensitivity and specificity. RESULTS: Using the glass-mercury measurement as the standard, both the supralingual and tympanic measurements showed an overall specificity of 62.8% and sensitivity of 63.3%. Correlation between rectal and supralingual was 0.62, and correlation between rectal and tympanic was 0.71. CONCLUSIONS: The Paci-Temp provides temperature readings that are similar to the tympanic method as compared to the rectal method. Further research on at-home thermometers is needed.     

A comparison of temperature measurements using three ear thermometers

Following anecdotal and research-based reports of inaccuracies encountered with the use of ear thermometers in patient care settings, this two-phase study was designed to compare the accuracy of three ear thermometers when used in a multioperator environment. The within-subject variation (limits of agreement) in ear temperature measurements obtained with the three ear thermometers in a multioperator condition by using an oral temperature reference standard ranged from +/- 1.25 degrees F to 1.85 degrees F. In multioperator, multisubject patient care environments using a pulmonary artery catheter core temperature as the reference standard, the limits of agreement for ear temperature measurements obtained with the three different ear thermometers ranged from +/- 2.19 degrees F to 2.85 degrees F. These results suggest that there is substantial variation in ear measurements and raise questions about the use of ear thermometers when there are multiple personnel taking temperatures, as occurs in hospital-based clinical practice environments. Handedness of the operator, position of the patient, and the ear used for measurement did not produce clinically significant variability in ear temperature measurements.     

Temperature, age, and recurrence of febrile seizure

OBJECTIVE: Prediction of a recurrent febrile seizure during subsequent episodes of fever. DESIGN: Study of the data of the temperatures, seizure recurrences, and baseline patient characteristics that were collected at a randomized placebo controlled trial of ibuprofen syrup to prevent febrile seizure recurrences. SETTING: Two pediatric hospitals in the Netherlands. PATIENTS: A total of 230 children with an increased risk of febrile seizure recurrence. MAIN OUTCOME MEASURE: Seizure recurrence during a subsequent fever episode. RESULTS: A total of 509 episodes of fever were registered with 67 recurrences; 35 (52%) recurrences within the first 2 hours after fever of onset had a lower median temperature (39.3 degrees C) than 32 (48%) after more than 2 hours of fever (40.0 degrees C, P<.001). Poisson regression analysis resulted in 3 univariably significant (P<.05) predictors of a recurrence of seizure during a subsequent episode of fever. In a multivariable model, they were corrected for their correlation: interval between the last previous seizure and fever of onset less than 6 months (relative risk= 1.3 [95% confidence interval: 0.8-2.4]), age at fever of onset (relative risk=0.7 [95% confidence interval: 0.5-1.0] per year increase) and temperature at fever of onset (relative risk = 1.7 [95% confidence interval: 1.1-2.8] per degree Celsius increase). CONCLUSIONS: Half of the recurrent seizures occur in the first 2 hours after fever of onset of a subsequent fever episode. If seizure recurs at a later time, the temperature at seizure is higher compared with recurrences occurring in the first 2 hours of fever. Young age at fever of onset, high temperature at fever of onset, and high temperature during the episode of fever are associated with an increased risk of a recurrent febrile seizure at the moment that a child with a history of febrile seizures has fever again.     

Fever and antipyresis in the lizard Dipsosaurus dorsalis

Lizards (Dipsosaurus dorsalis) were placed in a desertlike environment in which the ambient temperature (Ta) at night (1800-0600 h) was 12 degrees C and the day (0600-1800 h) Ta was between 30 and 55 degrees C depending on the location within the chamber. When dead Aeromonas hydrophila (4 X 10(9) organisms) was injected into nine lizards, an elevation in body temperature (Tb) of 2.7 degrees C was observed during the same day. On the day after bacterial injection the lizards' body temperatures averaged 41.6 degrees C, an increase of 4.2 degrees C over their control day Tb. Further investigations on the febrile response of D. dorsalis were conducted at the University of Wisconsin's Biotron, where there exists a simulated desert environment with the light intensity, temperature, and humidity closely parelleling a typical spring day in the southwestern desert of the United States (the natural habitat of Dipsosaurus). In this environment injection of dead bacteria into seven lizards led to an average febrile response of similar magnitude (Tb = 40.5 degrees C) but with a longer latency than that found at the University of Michigan. Injection of 13 lizards with live A. hydrophila (5 X 10(9) organism subcut.) in the simulated desert at Michigan led to a daytime fever averaging 2.3 degrees C (mean Tb = 40.6 degrees C) over a 5-day period. During the 6th and 7th day the lizards' body temperature returned to the normal or afebrile level. Injections of sodium salicylate along with dead A. hydrophila resulted in a dose-dependent attenuation of the febrile response. These results demonstrate that the reptilian febrile response is strikingly similar to avian and mammalian fever and suggest a common origin and perhaps function for the febrile mechanism.     

Evaluation of ear temperature measurements in a geriatric department

We evaluated an infrared tympanic thermometer (Genius 3000A) by comparing it with parallel measurements with an electronic rectal thermometer (Philips HP 5316) on 121 patients admitted to a geriatric department. Rectal temperature was on average 0.14 degree C +/- (ISD) above the ear temperature. 95% of the differences are within the interval from -1.18 degrees C to 1.46 degrees C. The coefficient of determination was only 0.30. The tympanic thermometer, Genius 3000A, cannot be recommended for daily use on a geriatric ward.     

Correcting respiratory rate for the presence of fever

This study defines what degree of respiratory rate (RR) elevation can be attributed to fever using a double blind randomized pre- and post-acetaminophen comparison of vital signs of febrile children presenting to an outpatient clinic. Inclusion criteria were aged between 6 weeks and 24 months, fever between 38.5 and 40.1 degrees C, no serious illness such as sepsis, and no recent receipt of antipyretics or antibiotics. RRs counted over 1 min and rectal temperatures were recorded by a trained observer before, and 1 and 1.5 hours (hr) after receipt of 10-15 mg/kg/dose of either acetaminophen (A) or placebo (P). Randomization produced groups A (n = 54), and P (n = 50) with similar mean age (12.3 vs 12.8 mo.), gender distribution (57 vs 54% female), baseline temperature (39.1 vs 39.1 degrees C), baseline RR (44 vs 45), and hours of fever prior to visit (42 vs 37 hr). The most common diagnoses were otitis media (49%), viral syndrome (18%), upper respiratory infection (16%) or gastroenteritis (7%). The mean temperature decrement of group A was 0.4 degrees C at 1 hr and 0.9 degrees C at 1.5 hr compared to slight increases in fever of 0.3 degrees C at 1 hr and 1.5 hr in group P. Significant decreases in RR occurred in group A compared to group P at 1 hr (7.0 vs 1.9, p = 0.009) and 1.5 hr (10.8 vs 4.0, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

The effects of lipopolysaccharide (LPS) on the fever response in rats at different ambient temperatures

There is a complex interplay between the immune system, nervous system, and sleep. When an organism is challenged with lipopolysacchride (LPS), the immune system is stimulated, producing a fever response that is independent of ambient temperature, and an increase in slow-wave sleep (SWS). The study investigated sleep patterns of immune-challenged rats during the light phase cycle to determine the effects of various ambient temperatures. It was hypothesised that fever response would occur independently of ambient temperatures. Also, the febrile response would be monophasic, and there would be an increase in slow-wave sleep (SWS) and a decrease in rapid-eye-movement (REM) sleep. Thirty Wistar rats were randomly placed in 3 different ambient temperature groups, 22 degrees C, 15 degrees C, and 30 degrees C. Within each of these conditions, the same subjects served as control and experimental groups. Four animals were placed in 4 subsections of 2 standard boxes that were placed in the ambient-temperature box. The electrodes were connected to the analog to digital computer board, where all the data was processed and stored on a hard drive. The animals were injected I.P. with saline and recorded for a period of 6 h to establish a baseline. On Day 2, the same animals were injected I.P. with LPS and recorded for 6 h to determine the febrile effects of LPS on the immune system; the same procedure was repeated in the other ambient temperatures. The results have shown that animals experienced a monophasic fever response in low and normal temperatures, but not in the high temperatures. Although there was no increase in SWS, there was a significant decrease in REM sleep in 3 groups.     

Reliability of infra-red tympanic thermometry (ITT)

BACKGROUND: The ability to take a patient's temperature quickly, easily, and accurately is desirable in a variety of situations. However, in order to have confidence in the values obtained, it is important to quantify the reliability of the measurement. PURPOSE: The purpose of this study, therefore, was to determine the reliability of temperature measurements obtained by infra-red tympanic membrane thermometers. METHOD: This study examined intra-tester, inter-tester and inter-instrument reliability using two commercially available tympanic membrane thermometers. Forty-four college students (mean age 20.2 +/- 3.6 yr) had their tympanic membrane temperature taken by two investigators, each using two different instruments (ThermoScan Pro-1 and FirstTemp Genius). RESULTS: The results indicated a statistically significant difference between testers for each instrument. Similarly, there was a significant statistical difference between instruments within each tester. Correlations were moderately high (r = 0.66-0.88) between testers for each instrument, whereas correlations within instruments varied considerably between testers (r = 0.35-0.78). The intra-tester reliability was good for both testers using both instruments with all coefficients of variation (CV) less than 2%. Statistically significant differences were found between testers for each instrument and between instruments for each tester. A 2 x 2 ANOVA revealed a significant main effect for Tester and a significant Tester x Instrument interaction. CONCLUSION: We conclude that individual investigators are able to obtain reliable temperature measures when using either the FirstTemp Genius or ThermoScan Pro-1 instruments under resting laboratory conditions. However, inter-tester and inter-instrument reliability should be considered when collecting or comparing data.