Comparison of esophageal, rectal, axillary, bladder, tympanic, and pulmonary artery temperatures in children

Accuracy of non-invasive core temperature monitoring in infant and toddler patients: a prospective observational study

PURPOSE

Careful perioperative temperature management is important because it influences clinical outcomes. In pediatric patients, the esophageal temperature is the most accurate indicator of core temperature. However, it requires probe insertion into the body cavity, which is mildly invasive. Therefore, a non-invasive easily and continuously temperature monitor system is ideal. This study aimed to assess the accuracy of Temple Touch Pro™ (TTP), a non-invasive temperature monitoring using the heat flux technique, compared with esophageal (Tesoph) and rectal (Trect) temperature measurements in pediatric patients, especially in infants and toddlers.

METHODS

This single-center prospective observational study included 40 pediatric patients (< 3 years old) who underwent elective non-cardiac surgery. The accuracy of TTP was analyzed using Bland-Altman analysis and compared with Tesoph or Trect temperature measurements. The error was within ± 0.5 °C and was considered clinically acceptable.

RESULTS

The bias ± precision between TTP and Tesoph was 0.09 ± 0.28 °C, and 95% limits of agreement were  - 0.48 to 0.65 °C (error within ± 0.5 °C: 94.0%). The bias ± precision between TTP and Trect was 0.41 ± 0.38 °C and 95% limits of agreement were  - 0.35 to 1.17 °C (error within ± 0.5 °C: 68.5%). In infants, bias ± precision with 95% limits of agreement were 0.10 ± 0.30 °C with  - 0.50 to 0.69 °C (TTP vs. Tesoph) and 0.35 ± 0.29 °C with  - 0.23 to 0.92 °C (TTP vs. Trect).

CONCLUSION

Core temperature measurements using TTP in infants and toddlers were more accurate with Tesoph than with Trect. In the future, non-invasive TTP temperature monitoring will help perioperative temperature management in pediatric patients.

Feasibility and accuracy of pediatric core temperature measurement using an esophageal probe inserted through the gastric lumen of a second-generation supraglottic airway device: a prospective observational study

BACKGROUND

Accurate core temperature measurement in children is crucial; however, measuring esophageal temperature (TE) using a supraglottic airway device (SAD) can be challenging. Second-generation SADs, which have a gastric channel, can measure TE, and reduce gastric air volume. This study aimed to compare TE, measured using a probe inserted through the SAD gastric channel, with tympanic membrane (TTM) and forehead (TZHF) temperatures, measured using a zero-heat-flux cutaneous thermometer, with rectal temperature (TR).

METHODS

Temperature was recorded at 10-min intervals from 10 min after probe insertion until completion of surgery. We performed an equivalence test to evaluate whether the TE, TTM, and TZHF were equivalent to TR, with a margin of 0.3°C. Additionally, intraclass correlation coefficients (ICC) were calculated to assess the reliability of TE and TR at each time point.

RESULTS

We included 41 patients in the final analysis. In all patients, the esophageal probe was successfully inserted through the gastric channel of the SAD. When assessing agreement with TR as a reference, TE demonstrated equivalent results at all time points (P < 0.001 at 0, 10, 20, 30, and 40-min intervals and P = 0.018 at the 50-min interval), except at the completion of surgery (P = 0.697). TE also demonstrated good reliability with TR as a reference throughout the surgery (ICC > 0.75).

CONCLUSIONS

In children with SAD insertion, TE can be accurately and feasibly measured through the SAD's gastric channel, making it suitable for routine application.

Evaluating the Agreement between Oral, Armpit, and Ear Temperature Readings during Physical Activities in an Outdoor Setting

Accurate body temperature measurement is essential for monitoring and managing safety during outdoor activities. Physical activities are an essential consideration for public health, with sports taking up an important proportion of these. Athletes' performances can be directly affected by body temperature fluctuations, with overheating or hypothermia posing serious health risks. Monitoring these temperatures allows coaches and medical staff to make decisions that enhance performance and safety. Traditional methods, like oral, axillary, and tympanic readings, are widely used, but face challenges during intense physical activities in real-world environments. This study evaluated the agreement, correlation, and interchangeability of oral, axillary, and tympanic temperature measurements in outdoor exercise conditions. Systems developed for specific placements might generate different sensor readouts. Conducted as an observational field study, it involved 21 adult participants (11 males and 10 females, average age 25.14 ± 5.80 years) that underwent the Yo-Yo intermittent recovery test protocol on an outdoor court. The main outcomes measured were the agreement and correlation between temperature readings from the three methods, both before and after exercise. The results indicate poor agreement between the measurement sites, with significant deviations observed post-exercise. Although the Spearman correlation coefficients showed consistent temperature changes post-exercise across all methods, the standard deviations in the pairwise comparisons exceeded 0.67 °C. This study concluded that widely used temperature measurement methods are challenging to use during outdoor exercises and should not be considered interchangeable. This variability, especially after exercise, underscores the need for further research using gold standard temperature measurement methods to determine the most suitable site for accurate readings. Care should thus be taken when temperature screening is done at scale using traditional methods, as each measurement site should be considered within its own right.

Esophageal Versus Rectal Temperature Monitoring During Whole-Body Therapeutic Hypothermia for Hypoxic-Ischemic Encephalopathy: Association with Short- and Long-Term Outcomes

OBJECTIVE

To compare the short- and long-term outcomes of infants with hypoxic-ischemic encephalopathy (HIE) treated with whole-body therapeutic hypothermia (TH), monitored by esophageal vs rectal temperature.

STUDY DESIGN

We conducted a secondary analysis of the multicenter High-Dose Erythropoietin for Asphyxia and Encephalopathy (HEAL) trial. All infants had moderate or severe HIE and were treated with whole-body TH. The primary outcome was death or neurodevelopmental impairment (NDI) at 22-36 months of age. Secondary outcomes included seizures, evidence of brain injury on magnetic resonance imaging, and complications of hypothermia. Logistic regression was used with adjustment for disease severity and site as clustering variable because cooling modality differed by site.

RESULTS

Of the 500 infants who underwent TH, 294 (59%) and 206 (41%) had esophageal and rectal temperature monitoring, respectively. There were no differences in death or NDI, seizures, or evidence of injury on magnetic resonance imaging between the 2 groups. Infants treated with TH and rectal temperature monitoring had lower odds of overcooling (OR 0.52, 95% CI 0.34-0.80) and lower odds of hypotension (OR 0.57, 95% CI 0.39-0.84) compared with those with esophageal temperature monitoring.

CONCLUSIONS

Although infants undergoing TH with esophageal monitoring were more likely to experience overcooling and hypotension, the rate of death or NDI was similar whether esophageal monitoring or rectal temperature monitoring was used. Further studies are needed to investigate whether esophageal temperature monitoring during TH is associated with an increased risk of overcooling and hypotension.

Accuracy of a zero-heat-flux thermometer in cardiac surgery, a prospective, multicentre, method comparison study

Accurate measurement of core temperature is of utmost importance during on-pump cardiac surgery, for detection of hypothermia before cardiopulmonary bypass (CPB), guidance of temperature management on CPB, active rewarming on CPB and guidance of warming therapy after CPB. Most temperature measurement methods are known to become inaccurate during rapid changes in core temperature and suffer from delayed detection of temperature changes. Zero-heat-flux temperature (ZHF) measurement from the lateral forehead may be an alternative, non-invasive method quantifying the core temperature. A prospective, observational, multicentre study was conducted in one hundred patients scheduled for on-pump coronary artery bypass grafting. Core temperatures were measured every minute by two zero-heat-flux thermometer (SpotOn™) and a bladder thermometer and a pulmonary artery catheter (PAC) in the period after induction of anesthesia until CPB. Accuracy and precision of both methods were compared against core temperature measured in the pulmonary artery using the method of Bland and Altman. A high accuracy (around 0.1 °C) and a very good precision (Limits of agreement (LoA) - 0.6; 0.4 °C) were found between zero-heat-flux thermometer and core temperature measured by PAC. Among the two ZHF thermometers the bias was negligible (- 0.003 °C) with narrow LoA of - 0.42 °C and 0.41 °C. In contrast, bias between bladder temperature and PAC temperature was large (0.51 °C) with corresponding LoA of - 0.06 °C and 1.1 °C. ZHF thermometers are in contrast to bladder temperature a reliable core temperature monitor in cardiac surgery during the period after induction of anestesia until CPB. The zero-heat-flux method can provide clinicians reliably with continuous and non-invasive measurements of core temperature in normothermic and mild hypothermic temperature ranges and therefore can be helpful to guide temperature management.

Concordance of esophageal and tracheal temperatures in patients using breathing circuit with heated wire humidifier: A prospective observational study

RESULTS

After excluding 4 patients with an anesthesia duration of < 2 hours, data from 34 patients (1163 sets of tracheal and esophageal temperatures) were analyzed. Concordance correlation coefficient was 0.78. The overall mean bias (95% limits of agreement) between the tracheal and esophageal temperatures was -0.16°C (-0.65°C to 0.34°C). The percentage of temperature differences within ± 0.25°C was 73.5% ± 32.3, with a median of 89.4% [0,100]. The linear mixed-effects model revealed that the estimated intercept was 0.17°C with a 95% confidence interval (CI) of 0.13°C to 0.22°C. The duration of anesthesia and the number of temperature measurements were associated with higher concordance between the tracheal and esophageal temperatures in univariate analysis.

Non-Contact Infrared Thermometers and Thermal Scanners for Human Body Temperature Monitoring: A Systematic Review

In recent years, non-contact infrared thermometers (NCITs) and infrared thermography (IRT) have gained prominence as convenient, non-invasive tools for human body temperature measurement. Despite their widespread adoption in a range of settings, there remain questions about their accuracy under varying conditions. This systematic review sought to critically evaluate the performance of NCITs and IRT in body temperature monitoring, synthesizing evidence from a total of 72 unique settings from 32 studies. The studies incorporated in our review ranged from climate-controlled room investigations to clinical applications. Our primary findings showed that NCITs and IRT can provide accurate and reliable body temperature measurements in specific settings and conditions. We revealed that while both NCITs and IRT displayed a consistent positive correlation with conventional, contact-based temperature measurement tools, NCITs demonstrated slightly superior accuracy over IRT. A total of 29 of 50 settings from NCIT studies and 4 of 22 settings from IRT studies achieved accuracy levels within a range of ±0.3 °C. Furthermore, we found that several factors influenced the performance of these devices. These included the measurement location, the type of sensor, the reference and tool, individual physiological attributes, and the surrounding environmental conditions. Our research underscores the critical need for further studies in this area to refine our understanding of these influential factors and to develop standardized guidelines for the use of NCITs and IRT.

Heat stress in horses: a literature review

Healthy adult horses can balance accumulation and dissipation of body heat to maintain their body temperature between 37.5 and 38.5 °C, when they are in their thermoneutral zone (5 to 25 °C). However, under some circumstances, such as following strenuous exercise under hot, or hot and humid conditions, the accumulation of body heat exceeds dissipation and horses can suffer from heat stress. Prolonged or severe heat stress can lead to anhidrosis, heat stroke, or brain damage in the horse. To ameliorate the negative effects of high heat load in the body, early detection of heat stress and immediate human intervention is required to reduce the horse's elevated body temperature in a timely manner. Body temperature measurement and deviations from the normal range are used to detect heat stress. Rectal temperature is the most commonly used method to monitor body temperature in horses, but other body temperature monitoring technologies, percutaneous thermal sensing microchips or infrared thermometry, are currently being studied for routine monitoring of the body temperature of horses as a more practical alternative. When heat stress is detected, horses can be cooled down by cool water application, air movement over the horse (e.g., fans), or a combination of these. The early detection of heat stress and the use of the most effective cooling methods is important to improve the welfare of heat stressed horses.

A Core Body Temperature Retrieval Method for Microwave Radiometry when Tissue Permittivity is Unknown

This paper presents a novel method for core temperature retrieval using microwave radiometry when complex permittivity and heat transfer parameters of the tissue layers of the human subject are unknown. Previous works present methods for core temperature retrieval, but these methods do not account for population variation in the relevant electromagnetic and thermal parameters, which can increase measurement error beyond the clinically acceptable limit of 0.5°C. Pennes' bioheat model of a six-tissue-layer human head model combined with a coherent electromagnetic model simulate experimental data. To retrieve core temperature, nonlinear least squares optimization is then used to minimize the difference between the simulated experimental data and an exponential model for physical temperature and the coherent electromagnetic model. By using 20 frequencies spanning from 1-5 GHz, core temperature is retrieved while accounting for population variation in the permittivity and thermal parameters. A Monte Carlo simulation in which the thermal parameters and permittivity vary according to literature-derived, population-representative distributions and the core body temperature varies from 18-46°C is used to assess the utility of the retrieval method. Different antenna patterns are tested to explore the effect on retrieval accuracy. The retrieval method has a retrieval error of <0.1°C when only the thermal parameters are unknown and a retrieval error of <0.5°C when the thermal parameters and permittivity are unknown, which is within the clinically acceptable error range of 0.5°C. These results help progress the field of medical microwave radiometry toward being a clinically viable noninvasive measurement that is accurate when measuring all patients.

Development of a Coherent Model for Radiometric Core Body Temperature Sensing

This paper examines the utility of a wideband, physics-based model to determine human core body or brain temperature via microwave radiometry. Pennes's bioheat equation is applied to a six-layer human head model to generate the expected layered temperature profile during the development of a fever. The resulting temperature profile is fed into the forward electromagnetic (EM) model to determine the emitted brightness temperature at various points in time. To accurately retrieve physical temperature via radiometry, the utilized model must incorporate population variation statistics and cover a wide frequency band. The effect of human population variation on emitted brightness temperature is studied by varying the relevant thermal and EM parameters, and brightness temperature emissions are simulated from 0.1 MHz to 10 GHz. A Monte Carlo simulation combined with literature-derived statistical distributions for the thermal and EM parameters is performed to analyze population-level variation in resulting brightness temperature. Variation in thermal parameters affects the offset of the resulting brightness temperature signature, while EM parameter variation shifts the key maxima and minima of the signature. The layering of high and low permittivity layers creates these key maxima and minima via wave interference. This study is one of the first to apply a coherent model to and the first to examine the effect of population-representative variable distributions on radiometry for core temperature measurement. These results better inform the development of an on-body radiometer useful for core body temperature measurement across the human population.

A Novel Non-Invasive Thermometer for Continuous Core Body Temperature: Comparison with Tympanic Temperature in an Acute Stroke Clinical Setting

There is a growing research interest in wireless non-invasive solutions for core temperature estimation and their application in clinical settings. This study aimed to investigate the use of a novel wireless non-invasive heat flux-based thermometer in acute stroke patients admitted to a stroke unit and compare the measurements with the currently used infrared (IR) tympanic temperature readings. The study encompassed 30 acute ischemic stroke patients who underwent continuous measurement (Tcore) with the novel wearable non-invasive CORE device. Paired measurements of Tcore and tympanic temperature (Ttym) by using a standard IR-device were performed 3−5 times/day, yielding a total of 305 measurements. The predicted core temperatures (Tcore) were significantly correlated with Ttym (r = 0.89, p < 0.001). The comparison of the Tcore and Ttym measurements by Bland−Altman analysis showed a good agreement between them, with a low mean difference of 0.11 ± 0.34 °C, and no proportional bias was observed (B = −0.003, p = 0.923). The Tcore measurements correctly predicted the presence or absence of Ttym hyperthermia or fever in 94.1% and 97.4% of cases, respectively. Temperature monitoring with a novel wireless non-invasive heat flux-based thermometer could be a reliable alternative to the Ttym method for assessing core temperature in acute ischemic stroke patients.

The agreement of rectal temperature with gingival, ocular and metacarpal pad temperatures in clinically healthy dogs

AIMS

To compare alternative methods of recording body temperature (BT) with rectal temperature (RT) in clinically healthy dogs.

METHODS

This prospective study included 97 healthy mixed-breed dogs (43 females and 54 males). The gingival temperature (GT) was collected by using a human non-contact, infrared forehead thermometer, while ocular temperature (OT) and metacarpal pad temperature (MPT) were obtained with an infrared thermal camera. The degree of agreement was determined using the Bland-Altman method, with RT considered as the reference temperature.

RESULTS

A total of 382 readings were obtained from four different anatomical regions. The mean difference and their 95% limits of agreement for the differences between RT-GT, RT-OT, and RT-MPT were 0.18°C (-0.95 to 1.32°C), 0.79°C (-0.45 to 2.04°C), and 0.50°C (-0.63 to 1.62°C), respectively. The GT, OT, and MPT values were within ±0.5°C of RT for 65.9, 19.5, and 52.5% of dogs, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Although GT, OT, and MPT were a quick way to estimate BT in dogs, these measurements were not comparable with RT. The GT measurement achieved the best agreement with RT measurement (lowest bias and the highest proportion of measurements within ±0.5°C). The GT could be considered an option for monitoring changes to body temperature in clinically healthy dogs where RT measurement is not possible.

Comparative accuracy testing of non-contact infrared thermometers and temporal artery thermometers in an adult hospital setting

Background

NCIT are non-invasive devices for fever screening in children. However, evidence of their accuracy for fever screening in adults is lacking. This study aimed to compare the accuracy of non-contact infrared thermometers (NCIT) with temporal artery thermometers (TAT) in an adult hospital.

Methods

A prospective observational study was conducted on a convenience sample of non-infectious inpatients in 2 Australian hospitals. NCIT and TAT devices were used to collect body temperature recordings. Participant characteristics included age, gender, skin color, highest temperature, and antipyretic medications recorded in last 24-hour.

Results

In 265 patients, a mean difference of ± 0.26°C was recorded between the NCIT (36.64°C) and the reference TAT (36.90°C) temperature devices. Bland-Altman analysis showed that NCIT and TAT temperatures were closely aligned at temperatures <37.5°C, but not at temperatures >37.5°C. NCIT had low sensitivity (16.13%) at temperatures ≥37.5°C. An AUROC score of 0.67 (SD 0.05) demonstrated poor accuracy of the NCIT device at temperatures ≥37.5°C.

Conclusion

This is the first study to compare accuracy of NCIT thermometers to TAT in adult patients. Although mass fever screening is currently underway using NCIT, these results indicate that the NCIT may not be the most accurate device for fever mass screening during a pandemic.

Smart Patch for Skin Temperature: Preliminary Study to Evaluate Psychometrics and Feasibility

There is a need for continuous, non-invasive monitoring of biological data to assess health and wellbeing. Currently, many types of smart patches have been developed to continuously monitor body temperature, but few trials have been completed to evaluate psychometrics and feasibility for human subjects in real-life scenarios. The aim of this feasibility study was to evaluate the reliability, validity and usability of a smart patch measuring body temperature in healthy adults. The smart patch consisted of a fully integrated wearable wireless sensor with a multichannel temperature sensor, signal processing integrated circuit, wireless communication feature and a flexible battery. Thirty-five healthy adults were recruited for this test, carried out by wearing the patches on their upper chests for 24 h and checking their body temperature six times a day using infrared forehead thermometers as a gold standard for testing validity. Descriptive statistics, one-sampled and independent t-tests, Pearson’s correlation coefficients and Bland-Altman plot were examined for body temperatures between two measures. In addition, multiple linear regression, receiver operating characteristic (ROC) and qualitative content analysis were conducted. Among the 35 participants, 29 of them wore the patch for over 19 h (dropout rate: 17.14%). Mean body temperature measured by infrared forehead thermometers and smart patch ranged between 32.53 and 38.2 °C per person and were moderately correlated (r = 0.23–0.43) overall. Based on a Bland-Altman plot, approximately 94% of the measurements were located within one standard deviation (upper limit = 4.52, lower limit = −5.82). Most outliers were identified on the first measurement and were located below the lower limit. It is appropriate to use 37.5 °C in infrared forehead temperature as a cutoff to define febrile conditions. Users’ position while checking and ambient temperature and humidity are not affected to the smart patch body temperature. Overall, the participants showed high usability and satisfaction on the survey. Few participants reported discomfort due to limited daily activity, itchy skin or detaching concerns. In conclusion, epidermal electronic sensor technologies provide a promising method for continuously monitoring individuals’ body temperatures, even in real-life situations. Our study findings show the potential for smart patches to monitoring non-febrile condition in the community.

Toward Non-Invasive Core Body Temperature Sensing

This paper aims to explore the potential of a novel radiometry technique that leverages bio-matched antennas (BMAs), broadband measurements, and forward modeling of layered tissues for non-invasive and accurate core temperature monitoring. Our approach relies on the observation that electromagnetic waves penetrate to different depths depending on their frequency and dielectric properties of the medium and adapts radiative transfer models that have been successfully implemented in the past for layered geophysical media. Preliminary modeling and experimental results confirm feasibility.

Diagnostic test accuracy of new generation tympanic thermometry in children under different cutoffs: a systematic review and meta-analysis

Background

The infrared tympanic thermometer (IRTT) is a popular method for temperature screening in children, but it has been debated for the low accuracy and reproducibility compared with other measurements. This study was aimed to identify and quantify studies reporting the diagnostic accuracy of the new generation IRTT in children and to compare the sensitivity and specificity of IRTT under different cutoffs and give the optimal cutoff.

Methods

Articles were derived from a systematic search in PubMed, Web of Science Core Collection, and Embase, and were assessed for internal validity by the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2). The figure of risk of bias was created by Review Manager 5.3 and data were synthesized by MetaDisc 1.4.

Results

Twelve diagnostic studies, involving 4639 pediatric patients, were included. The cut-offs varied from 37.0 °C to 38.0 °C among these studies. The cut-off 37.8 °C was with the highest sROC AUC (0.97) and Youden Index (0.83) and was deemed to be the optimal cutoff.

Conclusion

The optimal cutoff for infrared tympanic thermometers is 37.8 °C. New Generation Tympanic Thermometry is with high diagnostic accuracy in pediatric patients and can be an alternative for fever screening in children.

Hypothermia as an adjuvant treatment in paediatric refractory or super-refractory status epilepticus

Therapeutic hypothermia is among the adjuvant therapies suggested for refractory or super-refractory status epilepticus (R/SR-SE) in paediatric patients. Experimental evidence of neuroprotective and antiseizure effects provides a strong rationale for using therapeutic hypothermia in patients with status epilepticus. Thus, hypothermia between 20°C and 33°C in animals with status epilepticus is associated not only with significantly less neuronal damage, predominantly in the hippocampal CA1, CA2, and CA3 areas, but also with increased seizure latency and decreased seizure frequency and duration. Therapeutic hypothermia has rarely been used in paediatric R/SR-SE. In the few reported cases, seizure control was markedly improved but nearly half the patients experienced recurrences after rewarming. Studies are needed to clarify the modalities and indications of therapeutic hypothermia in paediatric patients with R/SR-SE. WHAT THIS PAPER ADDS: Hypothermia at 20°C to 33°C is neuroprotective and has antiseizure effects in experimental status epilepticus. In children, antiseizure effects are marked but recurrences after rewarming are common.

Simple calculation of the optimal insertion depth of esophageal temperature probes in children

Placing an esophageal temperature probe (ETP) in the optimal esophageal site is important in various anesthetic and critical care settings to accurately monitor the core temperature of a pediatric patient. However, no reported study has provided a formula to calculate the optimal insertion depth of ETP placement in children based on direct measurement of the optimal depth. The aim of this study was to develop a simple and reliable method to determine the optimal depth of ETP placement in children via their mouth. Using preoperative chest computed tomography scans, intraoperative chest X-rays, and the actual depth of ETP insertion, we measured the optimal depth of ETP placement retrospectively in 181 children aged 3-13 years who underwent minimally invasive repairs of the pectus excavatum and removal of a pectus bar. A linear regression analysis was performed to assess the correlation of the optimal depth of ETP placement with the children's age, weight, and height. The optimal depth of ETP placement had a greater correlation with height than with age or weight, and the best-fit equation was '0.180 × height + 6.749 (cm) (R² = 0.920).' We obtained three simplified formulae, which showed no statistically significant difference in predicting the optimal depth of ETP placement: height/6 + 8 (cm), height/5 + 4 (cm), and height/5 + 5 (cm). The optimal depth of ETP via children's mouths has a close correlation with height and can be calculated with a simple formula 'height/5 + 5 (cm)'.

Dominance rank and the presence of sexually receptive females predict feces-measured body temperature in male chimpanzees

Quantifying the costs of mating is key for understanding life-history trade-offs. As a reflection of metabolic rate, body temperature is one metric for assaying these costs. However, conventional methods for measuring body temperature are invasive and unsuitable for the study of free-living populations of endangered species, including great apes. A promising proxy for body temperature is fecal temperature, the internal temperature of fecal deposits shortly following defecation. We validated this method with humans, finding that maximum fecal temperature is a reliable proxy for rectal temperature. We then applied this method to wild chimpanzees (Pan troglodytes schweinfurthii) at Ngogo, Kibale National Park, Uganda. We collected and analyzed 101 fecal temperature measurements from 43 adult chimpanzees (male: N = 28; female: N = 15). Chimpanzee fecal temperature ranged from 33.4 to 38.9 °C, with a mean of 35.8 °C. Although fecal temperature was not predicted by sex, age, or ambient temperature, male fecal temperature was 1.1 °C higher on days when sexually receptive females were present and was positively correlated with male dominance rank. Post hoc analyses showed that overall copulation rates, but not aggression rates, were positively correlated with fecal temperature, suggesting that sexual physiology and behavior best explain mating-related temperature variation. Together, these results indicate fecal temperature is a reliable proxy for core body temperature in large-bodied mammals, captures metabolic costs associated with male mating behavior, and represents a valuable noninvasive tool for biological field research.

Ingestible sensors correlate closely with peripheral temperature measurements in febrile patients

BACKGROUNDS

Reliable non-invasive methods for measuring body temperature are essential for the diagnosis and monitoring of infectious disease.

METHODS

This study used Intraclass Correlation Coefficients (ICC) and the Bland- Altman plot to analyse the agreement between temperature measurements using an ingestible capsule sensor, a skin sensor and two non-invasive peripheral temperature measurements (axillary and infrared non-contact), collected from a population of febrile patient admitted for infectious disease.

RESULTS

Of the 77 febrile patients screened, 26 patients were enrolled. The ICC between axillary temperature measurements (Taxi) vs. non-contact measurements (Tno-c) were 0.34 [-0.18; 0.63], 0.87 [0.55; 0.94] between Taxi vs. ingestible capsule measurements (Tcap) and 0.12 [-0.09; 0.37] between Taxi vs. Tetac. The mean difference between Taxi vs Tno-c was -1.18 °C with limits of agreement (LoA) from -2.96 to 0.58 °C. The mean difference between Taxi vs Tcap was 0.48 °C, with LoA from -0.60 to 1.56 °C. The mean difference between Taxi vs Tetac was -4.23 °C with LoA from -7.22 to -1.23 °C.

CONCLUSIONS

Ingestible capsule measurements are reliable enough to adequately estimate the core body temperature in clinical practice. Its non-invasiveness, and the real-time remote control offer new opportunities for future research into fever during infectious diseases.

Validation of non-invasive brain temperature estimation models during swine therapeutic hypothermia

OBJECTIVES

This paper introduces a mathematical model that can estimate deep brain temperature during therapeutic hypothermia (TH) based on a double sensor method (DSM). Although the cerebral temperature is more important than the non-cerebral core temperature during TH, pulmonary artery (PA), rectal, and esophageal measurements (i.e. the typical core temperature measurement locations) have all been used for target temperature management. This is because there is no safe means of measuring the exact brain temperature.

APPROACH

We applied a double sensor thermometer to the subject's forehead to measure the cerebral temperature non-invasively. Invasive and non-invasive brain temperature readings were acquired for 11 pigs, seven of which were used to develop an optimal model using jackknife resampling and four of which were used to test the model.

MAIN RESULTS

The logit model exhibited the best performance of 0.134 °C root mean square error and a 0.993 Lin's concordance correlation coefficient (CCC). Each test dataset had acceptable results in that each 95% limit of agreement was within the range of clinical acceptance of [-0.5 °C, 0.5 °C]. Three of the four datasets yielded an 'almost perfect' score for Lin's CCC.

SIGNIFICANCE

Only a small number of studies have compared invasively and non-invasively measured brain temperatures, while most previous studies have concentrated on comparison with the core temperature. Furthermore, the possibility of measuring the exact brain temperature safely during TH using a DSM is shown in this work.

Top 10 Research Questions Related to Preventing Sudden Death in Sport and Physical Activity

Participation in organized sport and recreational activities presents an innate risk for serious morbidity and mortality. Although death during sport or physical activity has many causes, advancements in sports medicine and evidence-based standards of care have allowed clinicians to prevent, recognize, and treat potentially fatal injuries more effectively. With the continual progress of research and technology, current standards of care are evolving to enhance patient outcomes. In this article, we provided 10 key questions related to the leading causes and treatment of sudden death in sport and physical activity, where future research will support safer participation for athletes and recreational enthusiasts. The current evidence indicates that most deaths can be avoided when proper strategies are in place to prevent occurrence or provide optimal care.

Targeted temperature management in the ICU: Guidelines from a French expert panel

Over the recent period, the use of induced hypothermia has gained an increasing interest for critically ill patients, in particular in brain-injured patients. The term "targeted temperature management" (TTM) has now emerged as the most appropriate when referring to interventions used to reach and maintain a specific level temperature for each individual. TTM may be used to prevent fever, to maintain normothermia, or to lower core temperature. This treatment is widely used in intensive care units, mostly as a primary neuroprotective method. Indications are, however, associated with variable levels of evidence based on inhomogeneous or even contradictory literature. Our aim was to conduct a systematic analysis of the published data in order to provide guidelines. We present herein recommendations for the use of TTM in adult and paediatric critically ill patients developed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) method. These guidelines were conducted by a group of experts from the French Intensive Care Society (Société de réanimation de langue française [SRLF]) and the French Society of Anesthesia and Intensive Care Medicine (Société francaise d'anesthésie réanimation [SFAR]) with the participation of the French Emergency Medicine Association (Société française de médecine d'urgence [SFMU]), the French Group for Pediatric Intensive Care and Emergencies (Groupe francophone de réanimation et urgences pédiatriques [GFRUP]), the French National Association of Neuro-Anesthesiology and Critical Care (Association nationale de neuro-anesthésie réanimation française [ANARLF]), and the French Neurovascular Society (Société française neurovasculaire [SFNV]). Fifteen experts and two coordinators agreed to consider questions concerning TTM and its practical implementation in five clinical situations: cardiac arrest, traumatic brain injury, stroke, other brain injuries, and shock. This resulted in 30 recommendations: 3 recommendations were strong (Grade 1), 13 were weak (Grade 2), and 14 were experts' opinions. After two rounds of rating and various amendments, a strong agreement from voting participants was obtained for all 30 (100%) recommendations, which are exposed in the present article.

Targeted temperature management in the ICU: guidelines from a French expert panel

Over the recent period, the use of induced hypothermia has gained an increasing interest for critically ill patients, in particular in brain-injured patients. The term “targeted temperature management” (TTM) has now emerged as the most appropriate when referring to interventions used to reach and maintain a specific level temperature for each individual. TTM may be used to prevent fever, to maintain normothermia, or to lower core temperature. This treatment is widely used in intensive care units, mostly as a primary neuroprotective method. Indications are, however, associated with variable levels of evidence based on inhomogeneous or even contradictory literature. Our aim was to conduct a systematic analysis of the published data in order to provide guidelines. We present herein recommendations for the use of TTM in adult and paediatric critically ill patients developed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) method. These guidelines were conducted by a group of experts from the French Intensive Care Society (Société de Réanimation de Langue Française [SRLF]) and the French Society of Anesthesia and Intensive Care Medicine (Société Francaise d’Anesthésie Réanimation [SFAR]) with the participation of the French Emergency Medicine Association (Société Française de Médecine d’Urgence [SFMU]), the French Group for Pediatric Intensive Care and Emergencies (Groupe Francophone de Réanimation et Urgences Pédiatriques [GFRUP]), the French National Association of Neuro-Anesthesiology and Critical Care (Association Nationale de Neuro-Anesthésie Réanimation Française [ANARLF]), and the French Neurovascular Society (Société Française Neurovasculaire [SFNV]). Fifteen experts and two coordinators agreed to consider questions concerning TTM and its practical implementation in five clinical situations: cardiac arrest, traumatic brain injury, stroke, other brain injuries, and shock. This resulted in 30 recommendations: 3 recommendations were strong (Grade 1), 13 were weak (Grade 2), and 14 were experts’ opinions. After two rounds of rating and various amendments, a strong agreement from voting participants was obtained for all 30 (100%) recommendations, which are exposed in the present article.

Re-visiting the tympanic membrane vicinity as core body temperature measurement site

Core body temperature (CBT) is an important and commonly used indicator of human health and endurance performance. A rise in baseline CBT can be attributed to an onset of flu, infection or even thermoregulatory failure when it becomes excessive. Sites which have been used for measurement of CBT include the pulmonary artery, the esophagus, the rectum and the tympanic membrane. Among them, the tympanic membrane is an attractive measurement site for CBT due to its unobtrusive nature and ease of measurement facilitated, especially when continuous CBT measurements are needed for monitoring such as during military, occupational and sporting settings. However, to-date, there are still polarizing views on the suitability of tympanic membrane as a CBT site. This paper will revisit a number of key unresolved issues in the literature and also presents, for the first time, a benchmark of the middle ear temperature against temperature measurements from other sites. Results from experiments carried out on human and primate subjects will be presented to draw a fresh set of insights against the backdrop of hypotheses and controversies.

Assessment of axillary temperature for the evaluation of normal body temperature of healthy young adults at rest in a thermoneutral environment

Background

The aims of this study were to (1) evaluate whether recently introduced methods of measuring axillary temperature are reliable, (2) examine if individuals know their baseline body temperature based on an actual measurement, and (3) assess the factors affecting axillary temperature and reevaluate the meaning of the axillary temperature.

Methods

Subjects were healthy young men and women (n = 76 and n = 65, respectively). Three measurements were obtained: (1) axillary temperature using a digital thermometer in a predictive mode requiring 10 s (T_ax-10 s), (2) axillary temperature using a digital thermometer in a standard mode requiring 10 min (T_ax-10 min), and (3) tympanic membrane temperature continuously measured by infrared thermometry (T_ty). The subjects answered questions about eating and exercise habits, sleep and menstrual cycles, and thermoregulation and reported what they believed their regular body temperature to be (T_reg).

Results

T_reg, T_ax-10 s, T_ax-10 min, and T_ty were 36.2 ± 0.4, 36.4 ± 0.5, 36.5 ± 0.4, and 36.8 ± 0.3 °C (mean ± SD), respectively. There were correlations between T_ty and T_ax-10 min, T_ty and T_ax-10 s, and T_ax-10 min and T_ax-10 s (r = .62, r = .46, and r = .59, respectively, P < .001), but not between T_reg and T_ax-10 s (r = .11, P = .20). A lower T_ax-10 s was associated with smaller body mass indices and irregular menstrual cycles.

Conclusions

Modern devices for measuring axillary temperature may have changed the range of body temperature that is recognized as normal. Core body temperature variations estimated by tympanic measurements were smaller than those estimated by axillary measurements. This variation of axillary temperature may be due to changes in the measurement methods introduced by modern devices and techniques. However, axillary temperature values correlated well with those of tympanic measurements, suggesting that the technique may reliably report an individual’s state of health. It is important for individuals to know their baseline axillary temperature to evaluate subsequent temperature measurements as normal or abnormal. Moreover, axillary temperature variations may, in part, reflect fat mass and changes due to the menstrual cycle.

Comparison of Gastrointestinal and Rectal Temperatures During Recovery After a Warm-Weather Road Race

CONTEXT

It has been well established that gastrointestinal temperature (TGI) tracks closely with rectal temperature (TREC) during exercise. However, the field use of TGI pills is still being examined, and little is known about how measurements obtained using these devices compare during recovery after exercise in warm weather.

OBJECTIVE

To compare TGI and TREC in runners who completed an 11.3-km warm-weather road race and determine if runners with higher TGI and TREC present with greater passive cooling rates during recovery.

DESIGN

Cross-sectional study.

SETTING

Field.

PATIENTS OR OTHER PARTICIPANTS

Thirty recreationally active runners (15 men, 15 women; age = 39 ± 11 years, weight = 68.3 ± 11.7 kg, body fat = 19.2% ± 5.0%).

MAIN OUTCOME MEASURE(S)

The TGI and TREC were obtained immediately after the race and during a 20-minute passive rest at the 2014 Falmouth Road Race (heat index = 26.2°C ± 0.9°C). Temperatures were taken every 2 minutes during passive rest. The main dependent variables were mean bias and limits of agreement for TGI and TREC, using Bland-Altman analysis, and the 20-minute passive cooling rates for TGI and TREC.

RESULTS

No differences were evident between TGI and TREC throughout passive rest (P = .542). The passive cooling rates for TGI and TREC were 0.046 ± 0.031°C·min(-1) and 0.060 ± 0.036°C·min(-1), respectively. Runners with higher TGI and TREC at the start of cooling had higher cooling rates (R = 0.682, P < .001 and R = 0.54, P = .001, respectively). The mean bias of TGI during the 20-minute passive rest was -0.06°C ± 0.56°C with 95% limits of agreement of ±1.09°C.

CONCLUSIONS

After participants completed a warm-weather road race, TGI provided a valid measure of body temperature compared with the criterion measure of TREC. Therefore, TGI may be a viable option for monitoring postexercise-induced hyperthermia, if the pill is administered prophylactically.

A recommended early goal-directed management guideline for the prevention of hypothermia-related transfusion, morbidity, and mortality in severely injured trauma patients

Hypothermia is present in up to two-thirds of patients with severe injury, although it is often disregarded during the initial resuscitation. Studies have revealed that hypothermia is associated with mortality in a large percentage of trauma cases when the patient's temperature is below 32 °C. Risk factors include the severity of injury, wet clothing, low transport unit temperature, use of anesthesia, and prolonged surgery. Fortunately, associated coagulation disorders have been shown to completely resolve with aggressive warming. Selected passive and active warming techniques can be applied in damage control resuscitation. While treatment guidelines exist for acidosis and bleeding, there is no evidence-based approach to managing hypothermia in trauma patients. We synthesized a goal-directed algorithm for warming the severely injured patient that can be directly incorporated into current Advanced Trauma Life Support guidelines. This involves the early use of warming blankets and removal of wet clothing in the prehospital phase followed by aggressive rewarming on arrival at the hospital if the patient's injuries require damage control therapy. Future research in hypothermia management should concentrate on applying this treatment algorithm and should evaluate its influence on patient outcomes. This treatment strategy may help to reduce blood loss and improve morbidity and mortality in this population of patients.

Zero-Heat-Flux Thermometry for Non-Invasive Measurement of Core Body Temperature in Pigs

Hypothermia is a severe, unpleasant side effect during general anesthesia. Thus, temperature surveillance is a prerequisite in general anesthesia settings during experimental surgeries. The gold standard to measure the core body temperature (T_core) is placement of a Swan-Ganz catheter in the pulmonary artery, which is a highly invasive procedure. Therefore, T_core is commonly examined in the urine bladder and rectum. However, these procedures are known for their inaccuracy and delayed record of temperatures. Zero-heat-flux (ZHF) thermometry is an alternative, non-invasive method quantifying T_core in human patients by applying a thermosensoric patch to the lateral forehead. Since the porcine cranial anatomy is different to the human’s, the optimal location of the patch remains unclear to date. The aim was to compare three different patch locations of ZHF thermometry in a porcine hypothermia model. Hypothermia (33.0°C T_core) was conducted in 11 anesthetized female pigs (26-30kg). T_core was measured continuously by an invasive Swan-Ganz catheter in the pulmonary artery (T_pulm). A ZHF thermometry device was mounted on three different defined locations. The smallest average difference between T_pulm and T_ZHF during stable temperatures was 0.21 ± 0.16°C at location A, where the patch was placed directly behind the eye. Also during rapidly changing temperatures location A showed the smallest bias with 0.48 ± 0.29°C. Location A provided the most reliable data for T_core. Therefore, the ZHF thermometry patch should be placed directly behind the left temporal corner of the eye to provide a non-invasive method for accurate measurement of T_core in pigs.

Comparison of axillary and rectal temperatures for healthy Beagles in a temperature- and humidity-controlled environment

OBJECTIVE

To compare axillary and rectal temperature measurements obtained with a digital thermometer for Beagles in a temperature- and humidity-controlled environment.

ANIMALS

26 healthy Beagles (17 sexually intact males and 9 sexually intact females).

PROCEDURES

Dogs were maintained in a temperature- and humidity-controlled environment for 56 days before rectal and axillary temperatures were measured. Axillary and rectal temperatures were obtained in triplicate for each dog by use of a single commercially available manufacturer-calibrated digital thermometer.

RESULTS

Mean rectal and axillary temperatures of Beagles maintained in a temperature- and humidity-controlled environment were significantly different, with a median ± SD difference of 1.4° ± 0.15°C (range, 0.7° to 2.1°C). Mean rectal and axillary temperatures were 38.7°C (range, 37.6° to 39.5°C) and 37.2°C (range, 36.6° to 38.3°C), respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of this study indicated that the historical reference of a 0.55°C gradient between rectal and axillary temperatures that has been clinically used for veterinary patients was inaccurate for healthy Beagles in a temperature- and humidity-controlled environment. Rectal and axillary temperatures can be measured in veterinary patients. Reliable interpretation of axillary temperatures may accommodate patient comfort and reduce patient anxiety when serial measurement of temperatures is necessary. Further clinical studies will be needed.

Agreement between lower esophageal and nasopharyngeal temperatures in children ventilated with an endotracheal tube with leak

BACKGROUND

A temperature probe placed in the lower third of the esophagus accurately reflects core temperature in anesthetized children. Temperature probes are commonly placed in the nasopharynx in children, but when utilizing an uncuffed endotracheal tube (ETT) with a softly audible leak, ventilated gases from the trachea can escape upwards toward the nasopharynx, thereby potentially causing a cooling effect in the nasopharynx.

OBJECTIVES

We sought to establish if nasopharyngeal and lower esophageal temperatures are in agreement in children undergoing general anesthesia, both in scenarios of ventilation with a cuffed ETT that has minimal or no leak (cuff up), as well as an ETT with leak (cuff down).

METHODS

A prospective, crossover agreement study was performed on anesthetized children. Children were intubated with a MicroCuff(®) ETT and had temperature probes inserted into both the nasopharynx and lower esophagus. Under standardized ventilator and gas flow settings, temperatures were recorded with the ETT cuff inflated, and with the cuff deflated. Bland-Altman plots were utilized to assess agreement of temperatures.

RESULTS

Fifty patients successfully completed this study. The mean difference between esophageal and nasopharyngeal temperature was found to be -0.03°C in the presence of minimal or no leak around the ETT (cuff up), with 95% limits of agreement (LOA) of -0.22 to 0.15°C. The mean difference between esophageal and nasopharyngeal temperature was found to be 0.1°C when a larger leak existed around the ETT (cuff down), with LOA of -0.31 to 0.51°C.

CONCLUSIONS

Nasopharyngeal temperature accurately reflects lower esophageal temperature when there is minimal or no ETT leak. When a larger ETT leak is present, nasopharyngeal temperature is on average 0.1°C cooler than lower esophageal temperature. As the nasopharyngeal temperature probe site confers the advantage of simplicity of accurate placement compared to its esophageal counterpart, our findings support the use of nasopharyngeal temperature probes in children ventilated with both cuffed and uncuffed ETTs.

Comparison of axillary, tympanic membrane and rectal temperature measurement in cats

OBJECTIVES

Rectal temperature (RT) is routinely used to assess body temperature in cats but has limitations and can be poorly tolerated. Axillary temperature (AT) and tympanic membrane temperature (TMT) are reported alternatives. This study aimed to determine the differences between RT and AT, and between RT and TMT in cats. Additional aims were to examine the effect of environmental and patient factors on these differences and to assess patient tolerance to each technique.

METHODS

AT, TMT and RT were measured in immediate succession. Measurement order was randomised, as was the choice of left or right axilla and tympanic membrane. A digital thermometer and a veterinary infrared ear thermometer were used. The subjective tolerance of each procedure was recorded.

RESULTS

One hundred and fifty cats were included. Significantly more conscious cats were tolerant of AT (90.6%) than TMT (81.2%) and RT (53.0%). The rectal-axillary temperature difference ranged from -1.2°C to 1.4°C (median 0.1°C) and was within ± 0.5°C in 78.0% of cats. On multivariable analysis the difference was larger in overweight cats, neutered cats, cats in which the right axilla was used and as the RT increased. The rectal-tympanic membrane temperature difference ranged from -1.6°C to 3°C (median -0.3°C) and was within ± 0.5°C in 51.3% of cats, significantly fewer than for AT (P <0.001). The rectal-tympanic membrane temperature difference increased as the RT increased.

CONCLUSIONS AND RELEVANCE

TMT and AT should not be used interchangeably with RT in cats. When RT measurement is not possible, AT is recommended over TMT as it is better tolerated and significantly fewer cats had clinically unacceptable differences (>0.5°C). AT may more closely reflect RT in normal or underweight cats than it does in overweight cats.

Neonatal oesophageal and axilla temperatures in the neonatal intensive care unit care

AIM

To compare oesophageal and axilla temperatures in routine neonatal intensive care unit (NICU) care.

METHODS

Prospective observational study of NICU infants with indwelling oral/nasogastric tubes. Three simultaneous temperature measurements were taken: Physitemp axilla, digital Premie Faichney axilla in predictive mode and Physitemp oesophageal. Temperatures were measured on two separate days.

RESULTS

Fifty infants were studied over a range of gestational ages (median 28.9 weeks, IQR 25.8-30.6 weeks) and birthweights (median 1140 g, IQR 742-1498 g). Mean Physitemp oesophageal temperatures were 0.3 ± 0.1°C (range 0.1-0.6°C) higher than Physitemp axilla temperatures. After adjustment for weight, the Physitemp oesophageal-Physitemp axilla difference remained constant over the average oesophageal-axilla temperature range studied (p = 0.07). Physitemp oesophageal temperatures were not affected by weight (p = 0.2) or postmenstrual age (p = 0.51). Physitemp axilla temperatures decreased with increasing weight (p = 0.03) and postmenstrual age (p = 0.048). The Physitemp oesophageal-Physitemp axilla difference was greater for infants in cribs (mean ± SD = 0.4 ± 0.1°C) than in incubators (mean ± SD = 0.3 ± 0.1°C, p < 0.001). The relationship between oesophageal and digital Premie Faichney axilla temperature was similar to oesophageal and axilla Physitemp temperatures.

CONCLUSION

Over a range of infant temperatures encountered in routine NICU care, oesophageal temperature is higher than axilla temperature, although the difference is small. Axillary temperatures measured by digital thermometers in predictive mode are comparable to core oesophageal temperatures.

Temperature measurements in trauma patients: is the ear the key to the core?

Introduction

It is important to monitor the core temperature in a severely injured patient. The choice of method is controversial, and different thermometers and sites for measurement are used. The aim of this study was to investigate continuous epitympanic temperature measurement using an auditory canal sensor in potentially severely injured patients and to compare this method with other commonly used devices.

Methods

In this cohort of potentially severely injured patients, the core temperature was registered continuously using an epitympanic sensor in the auditory canal, beginning at the accident scene through the first hours after admittance to the hospital. According to clinical practice, other methods of measurement were employed during pre- and in-hospital diagnostics and therapeutics. The consistency between different methods was analysed using Bland-Altman plots, and the limits of agreement (LOA) and bias between methods was estimated.

Results

During the study period, 18 patients were included. A total of 393 temperature measurements were obtained using seven different methods. We found that temperature measurements in the auditory canal agreed satisfactorily with most other types of measurements. The most consistent measurement was observed with bladder measurements (bias 0.43 °C, LOA −0.47, 1.33 °C), which was constant over the temperature range investigated (30.0 - 38.3 °C).

Conclusion

Epitympanic temperature measurement in potentially severely injured patients was consistent with other methods that were commonly used to measure core temperature. The difference between measurement methods appeared to be constant over the relevant temperature range. Continuous epitympanic thermometry can be considered a reliable, cost-effective and simple alternative compared with more invasive methods of thermometry.

Infrared cameras are potential traceable "fixed points" for future thermometry studies

The National physical laboratory (NPL) requires "fixed points" whose temperatures have been established by the International Temperature Scale of 1990 (ITS 90) be used for device calibration. In practice, "near" blackbody radiators together with the standard platinum resistance thermometer is accepted as a standard. The aim of this study was to report the correlation and limits of agreement (LOA) of the thermal infrared camera and non-contact infrared temporal thermometer against each other and the "near" blackbody radiator. Temperature readings from an infrared thermography camera (FLIR T650sc) and a non-contact infrared temporal thermometer (Hubdic FS-700) were compared to a near blackbody (Hyperion R blackbody model 982) at 0.5 °C increments between 20-40 °C. At each increment, blackbody cavity temperature was confirmed with the platinum resistance thermometer. Measurements were taken initially with the thermal infrared camera followed by the infrared thermometer, with each device mounted in turn on a stand at a fixed distance of 20 cm and 5 cm from the blackbody aperture, respectively. The platinum thermometer under-estimated the blackbody temperature by 0.015 °C (95% LOA: -0.08 °C to 0.05 °C), in contrast to the thermal infrared camera and infrared thermometer which over-estimated the blackbody temperature by 0.16 °C (95% LOA: 0.03 °C to 0.28 °C) and 0.75 °C (95% LOA: -0.30 °C to 1.79 °C), respectively. Infrared thermometer over-estimates thermal infrared camera measurements by 0.6 °C (95% LOA: -0.46 °C to 1.65 °C). In conclusion, the thermal infrared camera is a potential temperature reference "fixed point" that could substitute mercury thermometers. However, further repeatability and reproducibility studies will be required with different models of thermal infrared cameras.

Pregnant women maintain body temperatures within safe limits during moderate-intensity aqua-aerobic classes conducted in pools heated up to 33 degrees Celsius: an observational study

QUESTION

What is the body temperature response of healthy pregnant women exercising at moderate intensity in an aqua-aerobics class where the water temperature is in the range of 28 to 33 degrees Celsius, as typically found in community swimming pools?

DESIGN

An observational study.

PARTICIPANTS

One hundred and nine women in the second and third trimester of pregnancy who were enrolled in a standardised aqua-aerobics class.

OUTCOME MEASURES

Tympanic temperature was measured at rest pre-immersion (T1), after 35minutes of moderate-intensity aqua-aerobic exercise (T2), after a further 10minutes of light exercise while still in the water (T3) and finally on departure from the facility (T4). The range of water temperatures in seven indoor community pools was 28.8 to 33.4 degrees Celsius.

RESULTS

Body temperature increased by a mean of 0.16 degrees Celsius (SD 0.35, p<0.001) at T2, was maintained at this level at T3 and had returned to pre-immersion resting values at T4. Regression analysis demonstrated that the temperature response was not related to the water temperature (T2 r = -0.01, p = 0.9; T3 r = -0.02, p=0.9; T4 r=0.03, p=0.8). Analysis of variance demonstrated no difference in body temperature response between participants when grouped in the cooler, medium and warmer water temperatures (T2 F=0.94, p=0.40; T3 F=0.93, p=0.40; T4 F=0.70, p=0.50).

CONCLUSIONS

Healthy pregnant women maintain body temperatures within safe limits during moderate-intensity aqua-aerobic exercise conducted in pools heated up to 33 degrees Celsius. The study provides evidence to inform guidelines for safe water temperatures for aqua-aerobic exercise during pregnancy.

Body temperature measurements in pigs during general anaesthesia

The aim was to compare rectal, pharyngeal and oesophageal temperature measurements in anaesthetized pigs. Data were compared using the Bland-Altman method, and correlation coefficients and error measures were calculated. Sixty-six sets of data were collected from 16 pigs weighing 16.2 ± 4.2 kg. The bias (and 95% limit of agreement) for rectal and pharyngeal compared with oesophageal temperature were 0.69 (-1.18 to 2.57) ℃ and 0.22 (-0.84 to 1.28) ℃, respectively. The correlation coefficients for rectal and pharyngeal compared with oesophageal temperature were 0.47 and 0.87, respectively. The absolute error for rectal and pharyngeal compared with oesophageal temperature was 0.7 ± 0.9℃ and 0.2 ± 0.5℃, respectively. Pharyngeal temperature measurement may be more suitable than rectal temperature measurement for estimation of oesophageal temperature during general anaesthesia of pigs.

Measurement of body temperature in 300 dogs with a novel noncontact infrared thermometer on the cornea in comparison to a standard rectal digital thermometer

OBJECTIVE

To assess the accuracy of obtaining body temperatures in dogs with a noncontact infrared thermometer (NCIT) on the cornea compared with a rectal digital thermometer (RDT).

DESIGN

Prospective single center study.

SETTING

University teaching hospital.

ANIMALS

Three hundred dogs presented with low, normal, or high body temperatures.

INTERVENTIONS

Three body temperature readings were measured by an RDT and by an NCIT on the cornea of the left eye by 2 investigators (experienced and inexperienced). Results obtained by the 2 methods were compared.

MEASUREMENTS AND MAIN RESULTS

Median body temperature measured by the experienced investigator with the RDT and the NCIT were 38.3°C (range 35.5°C-41.1°C; 95% CI: 38.2-38.4°C) and 37.7°C (35.9°C-40.1°C; 95% CI: 37.7°C-37.9°C), respectively. Measurement of RDT as well as of NCIT correlated well between both investigators (rRDT = 0.94; rNCIT = 0.82; respectively, P < 0.001 for both methods). Mean RDT and NCIT-temperature correlated poorly (r = 0.43; P < 0.001) when taken by the experienced investigator and even less by the nonexperienced investigator (r = 0.38; P < 0.001). Repeatability of the NCIT revealed an unsatisfactory value (0.24°C) compared to RDT measurement (0.12°C). Agreement between both devices in measuring low, normal, and high values, calculated by Cohens-Kappa, was unsatisfactory (к = 0.201; P < 0.001). Calculating the receiver operating characteristic curve to determine the best threshold for fever (defined as RDT temperature >39.0°C) showed an area under the curve of 0.76. Mean discomfort score was significantly lower using NCIT compared to RDT measurement (P < 0.001).

CONCLUSIONS

There was poor agreement between body temperatures obtained by RDT and NCIT. The corneal NCIT measurement tends to underrecognize hypothermic and hyperthermic conditions. Although the use of the NCIT yields faster results and is significantly more comfortable for the dog than the RDT measurement, it cannot be recommended in dogs at this time.

[Systematic review and meta-analyses of diagnostic accuracy of infrared thermometer when identifying fever in children]

PURPOSE

Infrared thermometers are increasingly used as a convenient, non-invasive assessment method for febrile children. However, the diagnostic accuracy of the infrared thermometer for children has been questioned, particularly in relation to sensitivity and specificity. The aim of this study was to evaluate diagnostic accuracy of infrared thermometers in febrile children.

METHODS

Articles published between 1966 and 2012 from periodicals indexed in the Ovid Medline, Embase, CINAHL, Cochrane, KoreaMed, NDSL, KERIS and other databases were selected, using the following keywords: 'infrared thermometer'. The QUADAS-II was applied to assess the internal validity of the diagnostic studies. Selected studies were analyzed using meta-analysis with MetaDisc 1.4.

RESULTS

Nineteen diagnostic studies with high methodological quality, involving 4,304 children, were included. The results of meta-analysis showed that the pooled sensitivity, specificity and AUC (Area Under the Curve) of infrared tympanic thermometers in children over 1 year were 0.80 (95% CI 0.78, 0.81), 0.94 (95% CI 0.93, 0.95) and 0.95 respectively. However the diagnostic accuracy of infrared tympanic thermometers in children with hyperthermia was low.

CONCLUSION

The diagnostic accuracy of infrared tympanic thermometer was similar to axillary and rectal thermometers indicating a need for further research to substantiate these findings in children with hyperthermia.

Monitoring temperature in children undergoing anaesthesia: a comparison of methods

Children undergoing anaesthesia are prone to hypothermia. Perioperative monitoring of patient temperature is, therefore, standard practice. Postoperative temperature is regarded as a key anaesthetic performance indicator in Australian hospitals. Many different methods and sites of temperature measurement are used perioperatively. It is unclear to what degree these methods might be interchangeable. The aim of this study was to determine the relationships between temperatures measured at different sites in anaesthetised children. Two hundred children, 0 to 17 years, undergoing general anaesthesia for elective non-cardiac surgery, were prospectively recruited. Temperature measurements were taken in the operating theatre concurrently at the nasopharynx, tympanic membranes, temporal artery, axilla and skin (chest). Patient age and weight were documented. Temperatures varied according to site of measurement. The mean difference from nasopharyngeal temperature to temperatures at left and right tympanic, temporal, axillary and cutaneous sites were +0.24°C, +0.24°C, +0.35°C, -0.38°C and -1.70°C, respectively. Levels of agreement to nasopharyngeal temperature were similar at tympanic, temporal and axillary sites. Tympanic and temporal temperatures were superior to axillary temperatures for detection of mild hypothermia (<36°C). Skin temperature showed a large variation from nasopharyngeal measurements. Our findings indicate that measured temperatures vary between sites. Understanding these variations is important for interpreting temperature readings.

Effect of magnetic resonance imaging on core body temperature in anaesthetised children

Children undergoing magnetic resonance imaging (MRI) often require general anaesthesia (GA). Children under GA are at risk of decreases in body temperature. This risk may be greater during MRI due to MRI scanners requiring cool ambient temperatures. Conversely, radiofrequency radiation emitted by MRI scanners is absorbed by the patient as heat energy, creating a risk of an increase in body temperature. The aim of this study was to determine the proportion of anaesthetised children undergoing an MRI scan who develop hyperthermia or hypothermia, and the risk factors associated with temperature changes in these children. Pre-scan and post-scan tympanic temperatures were obtained from 193 children (aged three months to six years) undergoing an MRI procedure under GA. No active warming or cooling devices were used during the MRI scans. The median duration for anaesthesia was 42 minutes (35 to 57 minutes). Fifty-two percent of children were hypothermic after their scan, while no subjects were hyperthermic after their scan. The mean (± standard deviation) pre-scan temperature was 36.2°C±0.5°C, and the mean (± standard deviation) post-scan temperature was 35.9°C±0.6°C (an overall mean temperature decrease of 0.28°C was observed [95% confidence interval, -0.36°C to -0.19°C], P <0.001). In conclusion, core body temperature was found to decrease slightly during an MRI scan under GA. These results suggest that more focus is needed regarding the cooling effects of GA agents during MRI, as opposed to the heating effects of the MRI scanner.

The incidence and prevention of hypothermia in newborn bonding after cesarean delivery: a randomized controlled trial

BACKGROUND

Little is known about thermoregulation of the newborn while bonding on the mother's chest immediately after cesarean delivery. Newborn hypothermia is associated with serious complications and should be avoided. Therefore, we evaluated whether newborns develop hypothermia during intraoperative bonding while positioned on their mothers' chests and investigated the effects of active cutaneous warming of the mothers and babies during a 20-minute intraoperative bonding period.

METHODS

We enrolled 40 parturients scheduled for elective cesarean delivery under spinal anesthesia. Mothers and their newborns were randomized to receive either passive insulation or forced-air skin-surface warming during the surgical procedure and bonding period. The primary outcome was neonatal core temperature at the end of the bonding period. Core temperatures of the newborns were measured with a rectal probe. Body temperatures of the mothers were assessed by sublingual measurements. Skin temperatures, thermal comfort of the mothers, and perioperative shivering were evaluated.

RESULTS

Without active warming from the beginning of the surgical procedure until the end of the bonding period, the mean (SD) neonatal core temperature decreased to 35.9 (0.6)°C. Seventeen of 21 (81%) newborns became hypothermic (defined as a core temperature below 36.5°C). Active skin-surface warming from the beginning of the surgical procedure until the end of the bonding period resulted in a neonatal core temperature of 37.0 (0.2)°C and a decreased incidence of hypothermia (1 of 19 (5%) newborns (P < 0.0001)). In addition, active warming increased the mean skin temperatures of the infants, maternal core and skin temperatures, maternal thermal comfort, and reduced perioperative shivering.

CONCLUSIONS

Active forced-air warming of mothers and newborns immediately after cesarean delivery reduces the incidence of infant and maternal hypothermia and maternal shivering, and increases maternal comfort.

Assessment of body temperature measurement options

Assessment of body temperature is important for decisions in nursing care, medical diagnosis, treatment and the need of laboratory tests. The definition of normal body temperature as 37°C was established in the middle of the 19th century. Since then the technical design and the accuracy of thermometers has been much improved. Knowledge of physical influence on the individual body temperature, such as thermoregulation and hormones, are still not taken into consideration in body temperature assessment. It is time for a change; the unadjusted mode should be used, without adjusting to another site and the same site of measurement should be used as far as possible. Peripheral sites, such as the axillary and the forehead site, are not recommended as an assessment of core body temperature in adults. Frail elderly individuals might have a low normal body temperature and therefore be at risk of being assessed as non-febrile. As the ear site is close to the hypothalamus and quickly responds to changes in the set point temperature, it is a preferable and recommendable site for measurement of body temperature.

Comparison of rectal, tympanic membrane and axillary temperature measurement methods in dogs

The aim of this study was to compare axillary and tympanic membrane (TM) temperature measurements to rectal temperature in a large group of clinical canine patients. We also sought to ascertain whether certain factors affected the differences between the measurements and to compare the ease of measurement. Axillary temperatures were easy to obtain but tended to be lower than rectal readings (median difference 0.6°C). In 54.7 per cent of dogs there was a difference of >0.5°C between the two readings. Weight, coat length, body condition score and breed size were significantly associated with the difference between the rectal and axillary temperature. TM temperatures were more similar to rectal temperatures (median difference 0°C) but in 25 per cent of dogs, there was a difference of >0.5°C between rectal and TM readings. TM measurements were less well tolerated than axillary measurements. None of the factors assessed were associated with the difference between the rectal and TM temperature. As a difference of >0.5°C has previously been described as unacceptable for different methods of temperature measurement, neither axillary nor TM temperatures are interchangeable with rectal temperatures for the measurement of body temperature.