A comparison of tympanic thermometer readings to pulmonary artery catheter core temperature recordings

Studying the Accuracy and Function of Different Thermometry Techniques for Measuring Body Temperature

The purpose of this study was to determine which thermometry technique is the most accurate for regular measurement of body temperature. We compared seven different commercially available thermometers with a gold standard medical-grade thermometer (Welch-Allyn): four digital infrared thermometers (Wellworks, Braun, Withings, MOBI), one digital sublingual thermometer (Braun), one zero heat flux thermometer (3M), and one infrared thermal imaging camera (FLIR One). Thirty young healthy adults participated in an experiment that altered core body temperature. After baseline measurements, participants placed their feet in a cold-water bath while consuming cold water for 30 min. Subsequently, feet were removed and covered with a blanket for 30 min. Throughout the session, temperature was recorded every 10 min with all devices. The Braun tympanic thermometer (left ear) had the best agreement with the gold standard (mean error: 0.044 °C). The FLIR One thermal imaging camera was the least accurate device (mean error: -0.522 °C). A sign test demonstrated that all thermometry devices were significantly different than the gold standard except for the Braun tympanic thermometer (left ear). Our study showed that not all temperature monitoring techniques are equal, and suggested that tympanic thermometers are the most accurate commercially available system for the regular measurement of body temperature.

Accuracy of Noninvasive Core Temperature Measurement in Acutely Ill Adults: The State of the Science

Accurate temperature measurement is critical to the assessment and management of temperature fluctuation in the acutely ill adult. Unfortunately, an accurate, noninvasive method to measure core temperature has yet to be established, and current instruments produce a wide range of temperatures for any given patient. This article provides an integrative review of studies comparing selected invasive and noninvasive temperature measurement methods in acutely ill, hospitalized adult patients. Medline and CINAHL databases were searched to locate published studies on temperature measurement in the adult hospitalized patient. A partial list of primary search terms included core temperature measurement, oral temperature measurement, temporal artery thermometry, and tympanic thermometers. Studies that were data based and included comparison of a tympanic, temporal artery, and/or oral noninvasive temperature measurement to a pulmonary artery or esophageal invasive core measurement in an adult population were included in the analysis. The search method produced 223 publications and abstracts for initial review; 23 (10%) met the inclusion criteria. The only study evaluating the use of temporal artery thermometry in the adult population found the instrument to be unreliable. Results also indicate that high-quality evidence supporting the accuracy of tympanic thermometry, the preferred instrument for noninvasive core temperature measurement in many acute care settings, is lacking, and in fact, the most recent high-quality studies evaluating the accuracy of this instrument fail to show support for its use. Evidence does, however, support the use of oral thermometry as an accurate means of temperature assessment in the adult, acutely ill population.

Accuracy of peripheral thermometers for estimating temperature: a systematic review and meta-analysis

BACKGROUND

Body temperature is commonly used to screen patients for infectious diseases, establish diagnoses, monitor therapy, and guide management decisions.

PURPOSE

To determine the accuracy of peripheral thermometers for estimating core body temperature in adults and children.

DATA SOURCES

MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and CINAHL Plus from inception to July 2015.

STUDY SELECTION

Prospective studies comparing the accuracy of peripheral (tympanic membrane, temporal artery, axillary, or oral) thermometers with central (pulmonary artery catheter, urinary bladder, esophageal, or rectal) thermometers.

DATA EXTRACTION

2 reviewers extracted data on study characteristics, methods, and outcomes and assessed the quality of individual studies.

DATA SYNTHESIS

75 studies (8682 patients) were included. Most studies were at high or unclear risk of patient selection bias (74%) or index test bias (67%). Compared with central thermometers, peripheral thermometers had pooled 95% limits of agreement (random-effects meta-analysis) outside the predefined clinically acceptable range (± 0.5 °C), especially among patients with fever (-1.44 °C to 1.46 °C for adults; -1.49 °C to 0.43 °C for children) and hypothermia (-2.07 °C to 1.90 °C for adults; no data for children). For detection of fever (bivariate random-effects meta-analysis), sensitivity was low (64% [95% CI, 55% to 72%]; I2 = 95.7%; P < 0.001) but specificity was high (96% [CI, 93% to 97%]; I2 = 96.3%; P < 0.001). Only 1 study reported sensitivity and specificity for the detection of hypothermia.

LIMITATIONS

High-quality data for some temperature measurement techniques are limited. Pooled data are associated with interstudy heterogeneity that is not fully explained by stratified and metaregression analyses.

CONCLUSION

Peripheral thermometers do not have clinically acceptable accuracy and should not be used when accurate measurement of body temperature will influence clinical decisions.

PRIMARY FUNDING SOURCE

None.

Evidence utilisation project: Management of inadvertent perioperative hypothermia. The challenges of implementing best practice recommendations in the perioperative environment

AIMS

The prevention of inadvertent perioperative hypothermia (IPH) remains an important issue in perioperative healthcare. The aims of this project were to: (i) assess current clinical practice in the management of IPH and (ii) promote best practice in the management of IPH in adult operating theatres.

METHODS

This project from August 2010 to March 2012 utilised a system of audit and feedback to implement best practice recommendations. Data were collected via chart audits against criteria developed from best practice recommendations for managing IPH. Evidence-based best practices, such as consistent temperature monitoring and patient warming, were implemented using multifaceted interventions.

RESULTS

Perioperative records for 73 patients (baseline) and 72 patients (post-implementation) were audited. Post-implementation audit showed an increase in patients with temperatures >36°C admitted to the post-anaesthetic care unit (PACU) (8%) and discharged from PACU (28%). The percentage of patients receiving preoperative temperature monitoring increased (38%); however, low levels of intraoperative monitoring remained (31% of patients with surgery of 30 min or longer duration). Small increases were found in patient warming of 5% intraoperatively and 8% postoperatively. Preoperative warming was not successfully implemented during this phase of the project.

CONCLUSION

Temperature monitoring, warming and rates of normothermia improved; however, barriers to best practice of IPH management were experienced, which negatively impacted on the project. Further stages of implementation and audit were added to further address IPH management in this department.

A transdisciplinary model integrating genetic, physiological, and psychological correlates of voluntary exercise

OBJECTIVE

Physical inactivity contributes to as many as 250,000 premature deaths per year (R. R. Pate et al., 1995). The authors' objective was to test a transdisciplinary model of the ways in which genetic variants, physiological factors, and psychological factors are thought to influence exercise with 64 healthy, regular exercisers.

DESIGN

In a within-subjects design, psychological and physiological responses to exercise were compared with responses to a sedentary activity.

MAIN OUTCOME MEASURES

The authors measured affective state, perceived exertion, heart rate, and temperature change in response to moderate exercise versus sedentary activity. They also quantified genotypes on a single nucleotide polymorphism in the brain-derived neurotrophic factor (BDNF) gene.

RESULTS AND CONCLUSIONS

The data show a relation between increases in positive affective states and acute exercise behavior, as opposed to a sedentary control. The BDNF gene moderated the effect of exercise on mood, heart rate, and perceived exertion. Physiological factors were, in turn, related to mood response, and mood response was a significant correlate of motivation to exercise in the future and of current exercise behavior. The model has potential as a framework for the basic study of the genetic, physiological, and psychological processes involved with voluntary exercise and as a tool for the applied examination of tailored exercise interventions and their efficacy for different subsets of individuals.

Can There Be a Standard for Temperature Measurement in the Pediatric Intensive Care Unit?

Temperature measurement is a commonly used assessment parameter when caring for the critically ill child. Interpreting the temperature measurement mode and what constitutes clinically significant thermal instability are poorly defined. Thus, decisions made regarding patient management based on temperature measurement can be challenging for caregivers. Infants and children have unique physioanatomic considerations that impact maintaining thermoregulation. Numerous routes for taking temperature measurements are described including the oral, axillary, tympanic (aural), rectal, skin, urinary bladder, pulmonary artery, esophageal, nasopharyngeal, supralingual (pacifier), and temporal-artery. Numerous studies on temperature measurement have been conducted on children of various ages using a variety of thermometers and routes in both the inpatient and outpatient setting. Although there are limited studies reported on the critically ill child, research data pertinent to the critically ill child from subjects in the neonatal intensive care unit, pediatric intensive care unit, operating room, and inpatient units are summarized.

Temperature taking in the ICU: which route is best?

Temperature measurement in an intensive care environment requires accurate estimation of core temperature via reliable equipment. Intermittent rectal probes were routinely used to measure core temperature in all extubated patients admitted to the Intensive Care Unit (ICU) which was the setting for this project. The nursing and medical staff identified various problems associated with this practice and a quality improvement project was implemented to compare temperatures recorded using three different routes: rectal, infrared tympanic and nasopharyngeal. Forty-nine patients were included in the study. Nasopharyngeal temperature measurements were recorded for all intubated patients and rectal temperature measurements were recorded for all extubated patients. During data collection, infrared tympanic temperature measurements were recorded at the same time as all other temperature measurements. The main comparison was between the rectal route and the infrared tympanic route because of the problems with the rectal probes that had been identified by staff. The results indicated statistically significant correlations between temperatures measured at the different sites. These results confirmed previous literature and the ICU involved in this study replaced rectal temperature measurement via intermittent probe insertion with infrared tympanic thermometry for the measurement of core temperature in extubated patients.

Comparison of rectal and infrared ear temperatures in older hospital inpatients

OBJECTIVES

To assess the agreement between infrared emission detection (IRED) ear and rectal temperatures and to determine the validity of IRED ear thermometry in detecting rectal fever.

DESIGN

Prospective, convenience sample, unblinded study.

SETTING

An acute geriatric unit (teaching hospital) and a multidisciplinary intensive care unit.

PARTICIPANTS

The study included 45 inpatients (26 women and 19 men), aged 78.3+/-6.9 years, admitted over a 4-month period. Twelve of the patients were definitely infected.

MEASUREMENTS

Sequential rectal (RT) and ear temperature (ET) measurements were performed using mercury-in-glass and IRED ear thermometers, respectively. IRED ear temperatures were measured at both ears (unadjusted mode), with the highest of six ear temperatures considered the true value.

RESULTS

Mean RT (37.39 degrees C +/- 0.52 degrees C) was significantly (P<.001) higher than mean ET (36.89 degrees C +/-0.59 degrees C). A highly significant positive correlation was found between RT and ET (slope = 0.69; 95% CI, 0.52-0.86; P<.001; r = 0.78). The mean bias (mean of the differences) between RT and ET was 0.50 degrees C +/-0.37 degrees C (95% CI, 0.41 degrees C-0.59 degrees C), and the 95% limits of agreement -0.22 degrees C and 1.23 degrees C (95% CI, -0.38 degrees C to 1.39 degrees C). According to the standard criterion (RT > or =37.6 degrees C), 14 patients were febrile. Using an optimum IRED ear fever threshold (37.2 degrees C), the sensitivity and specificity of IRED ear thermometry for predicting rectal fever were 86% and 89%, respectively (positive predictive value, 80%; negative predictive value, 93%).

CONCLUSIONS

The degree of agreement between rectal temperature and the highest of six IRED ear temperatures was acceptable. Using an optimal IRED ear fever threshold of 37.2 degrees C (99 degrees F), IRED ear thermometry had acceptable sensitivity and specificity for predicting rectal fever.

Hypothermia in trauma patients

Hypothermia occurs commonly in severely injured patients and is associated with a high mortality rate. It perturbs the normal homeostatic response to injury and affects multiple organ systems and physiologic processes. In trauma patients, hypothermia-induced coagulopathy often leads to marked bleeding diathesis and frequently provides a challenge for the surgeon. Once hypothermia occurs, it is often difficult to correct. Efforts to prevent and treat hypothermia in trauma patients should be instituted in the field and continued as an integral part of the resuscitation process. Hospital personnel and physicians at various levels caring for trauma patients from the initial injury and thereafter should bear in mind that a patient's temperature is as important as any other vital sign. Appropriate measures for preventing and treating hypothermia should be instituted promptly and tended to with utmost vigilance.

Accuracy of an infrared tympanic thermometer

BACKGROUND

The use of infrared thermometry to measure temperatures in hospitalized patients is increasing. Although infrared thermometers have been proven to be accurate when they are used by well-trained personnel, no previous studies have examined their accuracy during routine hospital use.

OBJECTIVE

To determine the accuracy and observer variability of temperatures measured with an infrared tympanic thermometer (TT).

DESIGN

Prospective, observational study.

SETTING

ICUs of a 300-bed teaching community hospital.

PATIENTS

Fifty-one critically ill patients.

MEASUREMENTS

The mean of three tympanic temperatures measured with the infrared TT (tempTTs) was compared to temperatures simultaneously measured with the thermistor of right heart catheters and rectal mercury thermometers for the following three groups of observers who had been certified in the use of the infrared TT: a single critical care nurse (CCN)/educator (Ed); CCNs, and floor nurses (FNs)/clinical care practitioners (CCPs).

RESULTS

Two rounds of measurements were given to 51 patients by 153 observers. Temperatures of the pulmonary artery (PA) measured with the thermistor of right heart catheters (tempPAs) ranged from 96.5 to 102.6 degrees F, with a mean (-/+ SD) of 99.3+/-1.1 degrees F. The intraobserver variabilities (correlation coefficients) of the tempTTs ranged from 0.90 for those measured by FNs/CCPs, to 0.92 for those measured by CCNs, to 0.98 for those measured by the CCN/Ed. Accuracy, arbitrarily defined as within a deviation of -/+0.5 degrees F of the tempPA, was 100% for the rectal mercury thermometer and 98.0% for the infrared TT when used by the CCN/Ed. The accuracy of the infrared TT was 80% when measured by CCNs and 61% when measured by FNs/CCPs. Differences between tempPAs and tempTTs measured by the CCN/Ed ranged from 0 to 0.7 degrees F, with a mean of 0.2 degrees F. Similarly, differences between tempPAs and tempTTs measured by CCNs ranged from 0 to 2.4 degrees F, with a mean difference of 0.3 degrees F. However, differences between tempPAs and tempTTs measured by FNs/CCPs ranged from 0 to 3.0 degrees F, with a mean of 0.6 degrees F (greater differences than those obtained by the CCNs; p < 0.01). The accuracy of rectal mercury thermometry was 100%. If a temperature > or = 101.0 degrees F had been considered as the threshold at which a fever is present, and if the mean of three measurements had been used to designate temperature, workups that were either inappropriately performed or omitted would have resulted from 2% of tempTTs measured by the CCN/Ed, 1% of those measured by CCNs, and 4% of those measured by FNs/CCPs.

CONCLUSION

When used properly, both tympanic and rectal thermometry are very accurate. However, the infrared TT produced measurements that were both less accurate and less reproducible when used by nurses who routinely used it in clinical practice.

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.

Oesophageal, rectal, axillary, tympanic and pulmonary artery temperatures during cardiac surgery

PURPOSE

The gradient between temperatures measured at different body sites is not constant; one factor which will change this gradient is rapid changes in body temperature. Measurement of this gradient was done in patients undergoing rapid changes in body temperature to establish the best site to measure temperature and to compare two brands of commercial tympanic thermometers.

METHOD

A total of 228 sets of temperatures were measured from probes in the oesophagus, rectum, and axilla and from two brands of tympanic thermometer and compared with pulmonary artery (PA) temperature in 18 adults during cardiac surgery.

RESULTS

Measurements from the oesophageal site was closest to PA readings (mean difference 0.0 +/- 0.5 degree C) compared with IVAC tympanic thermometer (mean difference -0.3 +/- 0.5 degree C), Genius tympanic thermometer (mean difference -0.4 +/- 0.5 degree C), axillary (mean difference 0.2 +/- 1.0 degrees C) and rectal (mean difference -0.4 +/- 1.0 degree C) readings. When data during cooling were analysed separately, all sites had similar gradients from PA except for rectal, which was larger. On rewarming, oesophageal readings were closest to PA readings; tympanic readings were closer to PA than were rectal or axillary readings. Readings from the two brands of tympanic thermometer were equivalent.

CONCLUSION

Oesophageal temperature is more accurate and will reflect rapid changes in body temperature better than tympanic, axillary, or rectal temperature. When oesophageal temperature cannot be measured, tympanic temperature done by a trained operator should become the reading of choice.

Can training improve the results with infrared tympanic thermometers?

BACKGROUND

Infrared tympanic thermometry (ITT) is a method for body temperature measurement. Correct measuring technique is said to be important to achieve good results with this method. The objective of this study was to investigate the accuracy and effect of training in the use of infrared tympanic thermometry (ITT) on the measurement results.

METHOD

Nurses trained in the use of ITT, and nurses not trained performed measurement sequences on 65 patients: one rectal and two ITT measurements in each sequence.

RESULTS

Mean rectal temperatures were significantly (P < 0.01) higher than with ITT (0.44 +/- 0.42 (SD) degree C for trained, 0.56 +/- 0.4 (SD) degree C for untrained). Coefficient of repeatability for ITT measurements was +/- 0.54 degree C for trained nurses, and +/- 0.48 degree C for untrained. With ITT temperatures adjusted upwards of 0.5 degree C, the sensitivity of ITT for detecting fever as defined by rectal measurements would be 70% for trained, and 54% for untrained nurses. Repeatability and sensitivity for trained and untrained nurses were not significantly (P > 0.05) different.

CONCLUSION

Training had little effect on the accuracy of the measurements. According to our results, ITT is often unreliable and should be used with caution.

Comparison of infrared ear thermometer derived and equilibrated rectal temperatures in estimating pulmonary artery temperatures

OBJECTIVES

To investigate the clinical accuracy of infrared ear thermometer derived and equilibrated rectal temperatures in estimating core body temperature. The clinical bias (i.e., mean difference between body sites), and variability (SD of the differences) of simultaneous temperatures were compared with pulmonary artery temperatures. Clinical repeatability (pooled SD of triplicate reading differences) was also examined for three ear infrared thermometers.

DESIGN

Prospective clinical study.

SETTING

A multidisciplinary, adult intensive care unit.

PATIENTS

Twenty patients with an existing pulmonary artery catheter were studied in a multidisciplinary, adult intensive care unit.

INTERVENTIONS

A single operator using optimum ear infrared technique and masked to ear and rectal temperatures recorded triplicate measurements with each of three infrared ear thermometers, each over a 4-min period with each infrared thermometer, while an assistant recorded temperatures. Infrared and rectal temperatures were compared with a simultaneous pulmonary artery temperature.

MEASUREMENTS AND MAIN RESULTS

Infrared ear thermometers and rectal thermometers were calibrated daily, and pulmonary artery catheters were calibrated on removal from the patient. Patients were grouped into afebrile and febrile groups, based on initial pulmonary artery temperature. Bias and variability were compared between thermometers using analysis of variance. Clinical bias, but not variability, was significantly different between three ear infrared thermometers (0.16 +/- 0.46 degrees C, 0.07 +/- 0.38 degrees C, and -0.22 +/- 0.47 degrees C). The repeatability was not different between ear infrared thermometers (range 0.13 degrees C to 0.14 degrees C). Rectal temperature had a significantly greater bias (average 0.3 degrees C), but less variability (average 0.2 degrees C). Bias was increased, and variability decreased for both rectal and infrared ear temperatures when pulmonary artery temperature was increased.

CONCLUSIONS

The three infrared ear thermometers studied provided a closer estimate of core body temperature than equilibrated rectal temperature. Clinical bias was greatest in febrile vs. afebrile intensive care unit patients.

Tympanic thermometry and minor ear surgery

Infra-red tympanic thermometry is a relatively new technique for measuring body temperature which requires the minimum of co-operation and is quick and easy to use. It is therefore ideal for use in children. Its use is becoming more widespread and as it is theoretically possible that minor ear surgery may interfere with function its reliability in these patients may be in question. Twenty-two children (mean age 5.3 years) who underwent myringotomy +/- grommet insertion had the tympanic temperature of each ear measured immediately before, and 15 minutes after, surgery on the recovery ward. No difference was found between the pre- and post-operative temperatures (mean difference--0.1 degree C, p > 0.1, paired t-test, hypothesized difference of 0). This thermometer appears to be a reliable way of monitoring body temperature on a paediatric ENT recovery ward in patients who have undergone minor ear surgery.