Ear Thermometer Research Articles

The Validity of Mass Body Temperature Screening with Ear Thermometers in a Warm Thermal Environment

Identification of people who have a fever in public places during the occurrence of emerging infectious diseases is essential for controlling disease spread. The measurement of body temperature could identify infected persons. The environment affects body temperature, but little is known about the validity of measurements under different thermal environments. Therefore, the aim of this study was to determine the validity of measuring body temperature in cold and warm environments. We recruited 50 participants aged 18-69 years (26 males, 24 females) to measure body temperature using an axillary thermometer and an ear thermometer and by infrared thermal imaging (thermography). The body temperature obtained with an axillary thermometer was used as a reference; receiver operating characteristic (ROC) analysis was conducted to determine the validity of temperatures obtained by measurement with an ear thermometer and thermography at 36.7°C (median of the axillary body temperature). The area under the ROC curve (AUC) indicates the validity of measurements. The AUC for ear thermometers in a warm environment (mean temperature: 20.0°C) showed a fair accuracy (AUC: 0.74 [95% CI: 0.64-0.83]), while that (AUC: 0.62 [95% CI: 0.51-0.72]) in a cold environment (mean temperature: 12.6°C) and measurements with thermography used in both environments (AUC: 0.57 [95% CI: 0.45-0.68] in a warm environment and AUC: 0.65 [95% CI: 0.54-0.76] in a cold environment) showed a low accuracy. In conclusion, in a warm environment, measurement of body temperature with an ear thermometer is a valid procedure and effective for mass body temperature screening.

The Validity of Mass Body Temperature Screening with Ear Thermometers in a Warm Thermal Environment

The Validity of Mass Body Temperature Screening with Ear Thermometers in a Warm Thermal Environment

The effects of measurement site and ambient temperature on body temperature values in healthy older adults: A cross-sectional comparative study

Background Accurate baseline body temperature measurement is essential for assessment. Tympanic membrane temperature (TMT) measurement is popular, but there is no consensus on whether it is as accurate as oral temperature (OT) for use with the elderly at varying ambient temperature levels. Objectives To test agreement between TMT and OT measurement of body temperature among an elderly population; and to explore whether agreement between the two sites depends on ambient temperature. Design A cross-sectional comparison study. Methods Two samples of older community-dwelling adults were recruited from 17 community senior citizen centers in Taipei, Taiwan in winter ( n = 262) and summer ( n = 257) of 2007. TMT and OT were simultaneously measured by electronic infrared ear thermometer and electronic digital thermometer. Ambient temperatures measured by digital thermo-hygrometer of the data collection setting were recorded when body temperature was taken. Results In winter mean TMT was 36.64 °C (S.D. 0.37), and mean OT was 36.74 °C (S.D. 0.18). In summer, the mean TMT was 37.05 °C (S.D. 0.30) and mean OT was 36.85 °C (S.D. 0.22). The relationship between TMT and OT were r = 0.42 ( p < 0.001) in winter and r = 0.57 ( p < 0.001) in summer. The values of OT were used as standard to assess the accuracy of the measurement. The bias between TMT and OT was −0.10 °C (S.D. 0.34) and 95% limits of agreement were 0.57 and −0.77 °C in winter; and bias was 0.20 °C (S.D. 0.25) and 95% limits of agreement were 0.69 and −0.29 °C in summer. The findings of this study demonstrate that the TMT has high variability that may under or over estimate body temperatures. Conclusions There is a lack of agreement in body temperatures values between TMT and OT in community-dwelling elderly in both winter and summer. OT was more stable than TMT regardless of ambient temperature influences. Therefore, the oral cavity is preferable to the TM site for temperature measurement in alert elderly. The limitation of this study is that hospitalized patients who are most likely to need temperature measurement are not included in this study.

Reducing thermal transient induced errors in thermopile sensors in ear thermometer applications

In ear thermometers and similar applications, thermopile sensors have to face a challenging thermal environment. The steady-state sensor temperature as well as the change of sensor temperature, heat flow, and thermal gradients have a significant impact on the sensor's reading. As opposed to the well-known steady-state sensor temperature (so-called “ambient temperature”), the effects of thermal transients have not jet been understood well in the past. They occur when the sensor warms up while the thermometer is inserted into the ear. They have to be treated in addition to the traditional (steady state) ambient temperature compensation. Isothermal packaging of the sensor significantly reduces the error due to thermal transients. This can be combined with mathematical prediction of the remaining error. Based on an analytical thermal model, we show that the error can be represented by a series of derivatives of the sensor housing temperature. Numerical calculation and compensation of the error in only first order combined with an isothermal package allows for an error reduction by the factor of 30.

Evaluation of the Cadi ThermoSENSOR Wireless Skin-Contact Thermometer Against Ear and Axillary Temperatures in Children

The Cadi ThermoSENSOR skin-contact thermometer measures body temperature continuously and transmits readings wirelessly to a central server. This study evaluated the ThermoSENSOR against ear temperatures (ETs) measured by a Braun ThermoScan ear thermometer and axillary temperatures (ATs) measured by a Terumo digital clinical thermometer. The test participants consisted of 109 children aged 6 months to 16 years from a pediatric ward. The sensor was attached to the lower abdomen at least 15 minutes before the first measurement. ET, AT, and ThermoSENSOR temperatures (TTs) were recorded up to three times at the usual measurement times. The TTs differed from ETs by −0.23°C ± 0.47°C (mean ± standard deviation, n = 271) and from ATs by +0.21°C ± 0.46°C (n = 270). The ETs differed from ATs by +0.43°C ± 0.42°C (n = 315). These results suggest that the TTs were comparable to the ETs and ATs.

Reliability of infrared ear thermometry in the prediction of rectal temperature in older inpatients

To assess the capability of infrared ear thermometry accurately to predict rectal temperature in older patients. Infrared ear thermometry is now commonly used for predicting body temperature in older patients. However, ear thermometry has been insufficiently evaluated in geriatric patients. Prospective, convenience sample, unblinded study. All patients (or their guardians) gave informed consent. Patients hospitalised in a geriatric unit underwent sequential ear and rectal temperatures measurements using two different models of infrared ear thermometers (ThermoScan and Genius) and a rectal probe, respectively. After a brief otoscopic examination, ear temperatures were measured twice at both ears with each thermometer, the highest of four measurements being retained for analysis. The rectal temperature was the reference standard. Hundred patients (31 males), aged 81 (SD 7) years completed the study. The mean rectal temperature was 37.3 degrees C (SD 0.7) degrees C (range 36.3-40.7 degrees C). Eighteen patients were febrile (rectal temperature >or= 37.8 degrees C). The mean bias between rectal and ear temperatures as measured with the ThermoScan was -0.20 degrees C (SD 0.32) degrees C and the 95% limits of agreement were -0.83 degrees C and 0.42 degrees C (95% CI, -0.88-0.48 degrees C). Using the Genius, the corresponding figures were -0.56 degrees C (SD 0.39) degrees C, -1.32 degrees C and 0.20 degrees C (95% CI, -1.39-0.27 degrees C). After correction for bias, the ThermoScan predicted the level of fever with a maximum error of 0.7 degrees C (mean error 0.3 degrees C). Using the Genius, the maximum error and the mean error were 1.6 degrees C and 0.4 degrees C, respectively. Infrared ear thermometry can predict rectal temperature in normothermic and in febrile inpatients with an acceptable level of accuracy. However, the predictive accuracy depends on both operator technique and quality of instrumentation. Proper technique (measuring in both ears) and optimal instrumentation (model of ear thermometer) are essential for accuracy.

Body Temperature Change During Anesthesia for Electroconvulsive Therapy: Implications for Quality Incentives in Anesthesiology

The American Society of Anesthesiologists has announced that perioperative normothermia is a "Quality Incentive in Anesthesiology." We examined whether we could meet this quality incentive in a simple population: patients undergoing anesthesia for electroconvulsive therapy (ECT). We compared infrared-measured ear temperature before anesthesia to temperature upon delivery of patients to the postanesthesia care unit (PACU) after 101 consecutive brief anesthetics to facilitate ECT. For 35 procedures, the patients had an infrared ear thermometer temperature of <36 degrees C before anesthesia was administered, and 18 had a temperature of <36 degrees C after anesthesia when transferred to the PACU. For 30 anesthetics, the patients' temperature decreased during anesthesia, for 64 anesthetics it increased during anesthesia, and for 7 it did not change. Overall examination of the data demonstrated no correlation between preprocedure and postprocedure temperature. We conclude that there was no consistent change in temperature during anesthesia between our study patients when anesthesia was administered to facilitate ECT. If patients' tympanic temperatures were below 36 degrees C upon admission to the PACU, it would be incorrect to conclude that intraprocedural temperature management measures were substandard. Also, current methods of measuring temperature may be inadequate to ascertain if patients are hypothermic after surgery. As the avoidance of hypothermia is a meritorious goal, anesthesia departments need to ensure that their temperature monitoring equipment is adequate to ensure accurate measurement of postanesthetic temperature if this variable is to be used as a quality incentive.

Meta‐analysis of diagnostic test studies using individual patient data and aggregate data

A meta-analysis of diagnostic test studies provides evidence-based results regarding the accuracy of a particular test, and usually involves synthesizing aggregate data (AD) from each study, such as the 2 by 2 tables of diagnostic accuracy. A bivariate random-effects meta-analysis (BRMA) can appropriately synthesize these tables, and leads to clinical results, such as the summary sensitivity and specificity across studies. However, translating such results into practice may be limited by between-study heterogeneity and that they relate to some 'average' patient across studies.In this paper we describe how the meta-analysis of individual patient data (IPD) from diagnostic studies can lead to clinical results more tailored to the individual patient. We develop IPD models that extend the BRMA framework to include study-level covariates, which help explain the between-study heterogeneity, and also patient-level covariates, which allow one to assess the effect of patient characteristics on test accuracy. We show how the inclusion of patient-level covariates requires a careful separation of within-study and across-study accuracy-covariate effects, as the latter are particularly prone to confounding. Our models are assessed through simulation and extended to allow IPD studies to be combined with AD studies, as IPD are not always available for all studies. Application is made to 23 studies assessing the accuracy of ear thermometers for diagnosing fever in children, with 16 IPD and 7 AD studies. The models reveal that between-study heterogeneity is partly explained by the use of different measurement devices, but there is no evidence that being an infant modifies diagnostic accuracy.

Improving the reliability of temperature measurements taken with clinical infrared ear thermometers

Infrared ear thermometer was developed and rapidly spread in Japan in the late 1990's, but users began to question the reliability of the temperature readings. AIST developed a new national standard for the calibration and conformity assessment of new ear thermometers, and also designed and organized the traceability system, conducted technological verification, and improved reliability of measured temperature, to meet the demands of Japanese industry and consumers. An international comparison of national measurement standards among Germany, UK, and AIST was conducted and the equality of the standards was experimentally verified to maintain international reliability.

Infrared Ear Thermometers Do Not Accurately Measure Core Temperature in Fire Fighters During Recovery

Infrared Ear Thermometers Do Not Accurately Measure Core Temperature in Fire Fighters During Recovery

In a systematic review, infrared ear thermometry for fever diagnosis in children finds poor sensitivity

Background and Objectives To investigate sensitivity and specificity of infrared ear thermometry compared to rectal thermometry to detect fever in children. Methods Systematic review of studies comparing rectal and infrared ear temperatures in children. Results Sensitivity and specificity estimates were highly heterogeneous, and displayed an inverse relationship suggestive of a threshold effect, due in part to the different offsets used to obtain adjusted tympanic temperatures depending on the ear thermometer mode. To account for this threshold effect, results from each study were summarized as a diagnostic odds ratio (DOR). These varied extensively across studies, suggesting that heterogeneity between study estimates is not fully explained by the threshold effect. Pooled estimates of sensitivity and specificity from random effects models were 63.7% (95% CI 55.6%, 71.8%) and 95.2% (95% CI 93.5%, 96.9%), respectively. Conclusion Pooled estimates of measures of diagnostic accuracy from these studies suggest that infrared ear thermometry would fail to diagnose fever in three or four out of every 10 febrile children (with fever defined by a rectal temperature of 38°C or above). These findings support our previous concerns about the use of infrared ear thermometers in situations where a failure to detect fever has serious implications.

Cryothérapie corps entier à –110 °C. Mesure des températures cutanées et centrale chez le sportif

Aims. – Whole body cryotherapy (WBC) at -110 °C has been in use since the eighties, essentially in Northern Europe, for the treatment of rheumatism diseases and also in sports medicine and traumatology. The objective of this work is to measure the effects of a WBC session on skin and core body temperatures, based on the medical protocol that we have been using on sportsmen and sportswomen for nearly two years, on a daily basis. Method. – Eleven sportspersons were included in the study, 10 men and 1 woman. Skin temperatures were measured in various places on the body using a laser thermometer, 5 minutes before the session and then immediately afterwards and 5, 10 and finally 20 minutes later. The core body temperature was measured using an ear thermometer. The cryotherapy session lasted 4 minutes. Results. – On exiting the cold chamber, the lowest temperatures were measured on the shin, with an average value of less than 10 °C. The skin temperatures rose very quickly, but the measured values remained lower than the reference temperatures after 20 minutes. As far as the core body temperature is concerned, we observed a significant decrease, but the value observed was both deferred and transient: 0.63 °C observed after 5 minutes. The difference was no longer significant after 20 minutes.

Traceability and calibration in temperature measurement: a clinical necessity

Patient temperature is a fundamental physiological measurement used primarily for observation and diagnosis, for example during surgery, intensive care, recuperation, or treatment. A variety of thermometers are used clinically and these can be separated into two categories, either contact (oral thermometers, rectal thermometers and temporal strips), or non-contact (ear thermometers, temporal thermometers and thermal imagers). To have the maximum confidence in the clinical performance of the temperature measurement instrument it is strongly desirable that the device be traceably calibrated to the International Temperature Scale of 1990 (ITS-90). Lack of traceable calibrations accredited to ISO17025 can lead to unreliability in temperature measurement and in some cases can have a deleterious effect on patient care. The National Physical Laboratory (NPL) maintains and disseminates the ITS-90 for contact and non-contact thermometry in the UK. The importance of accredited traceable calibrations and an outline of contact and non-contact thermometry standards are given here.

La précision ďun nouveau thermomètre auriculaire infrarouge chez des patients de cardiochirurgie

To evaluate the equivalency of the prototype of a new infrared ear thermometer (IRT 4000) in comparison to the temperature measurements of a pulmonary artery catheter (PAC) and a continual contact probe on the tympanic membrane. After approval by the local Ethics Committee, 26 (six female and 20 male) patients undergoing elective cardiac surgery were included in a single center open trial. During surgery, temperature measurements were recorded with the IRT 4000 in the left ear, and with a tympanic contact probe in the right ear, as well as with a PAC as reference. Measurements with the infrared ear thermometers and continual PAC values were recorded every six minutes. The average temperature measured with the IRT 4000 was 0.08 degrees C above the temperature of the PAC (95% confidence interval from -0.44-0.61 degrees C). Infrared ear thermometers 4000 temperature readings accurately reflect body core temperature and correlate well with the invasive PAC. Infrared ear thermometers may present a clinically useful alternative to the pulmonary artery thermometry for the measurement of core temperature in the perioperative setting or in the intensive care unit.

Infrared ear thermometers—parameters influencing their reading and accuracy

Infrared ear thermometers (IRETs) are extensively used for measuring the temperature of a human body. For accurate measurements with IRETs they have to be calibrated regularly with an appropriate and traceable calibration system. Such systems are neither widely available nor are there many competent (accredited) laboratories which can provide traceability for IRETs. This paper describes some important influential parameters in the calibration and use of IRETs, which were observed during the extensive research on IRETs and have not been reported in the literature yet. IRET readings, and consequently also their most important metrological characteristics, accuracy and uncertainty of measurement, depend on these influential parameters. According to our findings, we would like to warn users of medical radiation thermometers, not only IRETs but also forehead thermometers and infrared temperature scanning systems, that they should be extremely careful in selection, maintenance and use of medical radiation thermometers. Measurement accuracy, as it is required by several technical standards, is hard to achieve with the majority of currently available medical radiation thermometers.

La mesure de la température en pratique pédiatrique quotidienne

The use of rectal mercury thermometer has long been the standard method for measurement of body temperature. The restriction of mercury use since 1996 has led to development of other devices. The liquid crystal strip thermometer held against the forehead has a low sensitivity. The single-use chemical thermometer measures oral temperature. Its accuracy must be evaluated. Infrared ear thermometers are routinely used because it is convenient and fast to use. However, numerous studies have shown that it does not show sufficient correlation with rectal temperature, leading to the risk to miss cases of true fever. Rectal temperature remains the gold standard in case of fever. Rectal temperature measurement with an electronic device is well correlated with the glass mercury standard. Galistan thermometer accuracy must be evaluated because of sterilization of the whole device, which is not the case for the electronic thermometer. A paediatric study is necessary to evaluate the performance of this device in comparison with the electronic thermometer.

The Patient: A Novel Source of Error in Clinical Temperature Measurement Using Infrared Aural Thermometry

The vital signs are an important component of patient assessment. With respect to body temperature; there has been a move away from mercury-in-glass thermometers toward the relatively inexpensive, safer to use infrared tympanic, auricular, or ear thermometer. Although already in widespread use, the reliability of these devices has increasingly been called into question. Few studies, however, have considered that the problem might reside outside the device itself. To investigate the correlation between left ear temperature and right ear temperature using an infrared tympanic thermometer (ITT). A prospective, single-blind trail with randomized assignment of the first ear to be assessed. Welsh Institute of Chiropractic (WIOC), University of Glamorgan. One hundred and thirty two (132) asymptomatic subjects who were opportunistically sampled on entry into the WIOC. None of the subjects had any neurologic deficit, or any known underlying pathologic problems. All were students at the University of Glamorgan (age range, 18-48 years). A smaller sample of the same cohort was used on a separate occasion to compare ITTs from 2 different manufacturers using the same protocol. Measurement of ear (ear canal/tympanic) temperature bilaterally using an ITT. Bilateral asymmetry in ear canal temperature. Analysis consisted of nonparametric statistical tests, using Spearman's correlation for comparison and the Wilcoxon matched pairs test for differences. In 132 subjects who completed the main study, although a degree of correlation was found, the relationship did not extrapolate through zero. At temperatures more than 0.4 degrees C above or below 36.7 degrees C, there was a significant difference in temperature in the left compared with the right ear. Additionally, the left ear tended to register a lower temperature than the right ear at temperatures below 36.7 degrees C, whereas the left ear tended to read a higher temperature than the right ear above 36.7 degrees C. The authors suggest that clinicians consider measuring both ears, and take the greater of the readings to be a more accurate reflection of the patient's core temperature. The difference may perhaps even be related to the person's health. This change in methodology should increase the reliability of the measurement and go some way toward restoring confidence in the use of ITT devices.

Bilateral comparison of blackbody cavities for calibration of infrared ear thermometers between NPL and FE/LMK

The paper describes the comparison method and analyses the results of comparison in terms of agreement between the blackbody of the National Physical Laboratory (NPL), United Kingdom and four different blackbody cavities of the Laboratory of Metrology and Quality (LMK), at the University of Ljubljana, Faculty of Electrical Engineering (FE), Slovenia. Three cavity shapes are suggested in different standards as suitable for calibration of infrared ear thermometers (IRETs), while one cavity shape was proposed by the LMK. The agreement between blackbody cavities was determined with the help of platinum resistance thermometers. Two reference IRETs were used to check their stability and level of agreement between calibration results at different institutes and against different blackbody cavities. Measurements were performed with two IRETs, at the NPL in one cavity and at the LMK in four different cavities. The comparison was initiated to solve the problem of assuring proper traceability for IRETs and to present the solution to their users.

Temporal artery temperature measurements in healthy infants, children, and adolescents

Temporal artery temperature measurements in healthy infants, children, and adolescents

IR ear thermometers: what do they measure and how do they comply with the EU technical regulation?

Medical diagnostics and clinical practice rely extensively on test and measurement instrumentation. It is therefore of paramount importance that test and measurement instrumentation provides reliable data of sufficient stability, within appropriate limits of accuracy. At the same time the intended purpose of a particular measuring instrument has to be taken into account. The essential problem of every measuring instrument is that it measures and indicates basically what appears at the input of the measuring instrument, which might be significantly different from the real condition of a measurand. Namely, it is assumed that a measurand is stable, repeatable, and relatively unsusceptible to environmental influences. All these requirements are difficult to assure in a biological system and especially difficult in medical practice. Technology could easily provide high-resolution measurements, but due to natural instability of a measurand and various influential parameters the measurement uncertainty is inevitable. Sometimes even gross measurement errors are introduced. To achieve the expected accuracy for intended purpose is therefore much more demanding than merely relying on manufacturers' specifications. This paper describes and analyses the mentioned dilemmas in the case of widely used infrared ear thermometers, with their benefits and limitations, as well as with regard to the European technical regulation in the field of medical devices.