Core body temperature measurement: a comparison of axilla, tympanic membrane and pulmonary artery blood temperature

Noninvasive and Continuous Monitoring of the Core Body Temperature through the Quantitative Measurement of Blood Perfusion Rate

Core body temperature (CBT) is one of the four vital signs that must be monitored continuously. The continuous recording of CBT is possible through invasive methods by inserting a temperature probe into specific body sites. We report a novel method to monitor CBT through the quantitative measurement of skin blood perfusion rate (ωb,skin). By monitoring the skin temperature, heat flux, and ωb,skin, the arterial blood temperature, equivalent to CBT, can be extracted. ωb,skin is quantitatively evaluated thermally via sinusoidal heating with regulated thermal penetration depth so that the blood perfusion rate is acquired only in the skin. Its quantification is significant because it indicates various physiological events including hyper- or hypothermia, tissue death, and delineation of tumors. A subject showed promising results with steady values of ωb,skin and CBT of 5.2 ± 1.05 × 10-4 s-1 and 36.51 ± 0.23 °C, respectively. For periods where the subject's actual CBT (axillary temperature) did not fall within the estimated range, the average deviation from the actual CBT was only 0.07 °C. This study aims to develop a competent methodology capable of continuously monitoring the CBT and blood perfusion rate at a distant location from the core body region for the diagnosis of a patient's health condition with wearable devices.

A Simple Telemetry Sensor System for Monitoring Body Temperature in Rabbits-A Brief Report

Continuous body temperature measurement is an important means of studying inflammation and metabolic changes using experimental animals. Although expensive telemetry equipment for collecting multiple parameters is available for small animals, readily used devices for mediate- or large-sized animals are rather limited. In this study, we developed a new telemetry sensor system that can continuously monitor rabbit body temperature. The telemetry sensor was easily implanted subcutaneously in rabbits housed in the animal facility while temperature changes were continuously recorded by a personal computer. Temperature data obtained by the telemetry was consistent with the rectal temperature measured by a digital device. Analysis of body temperature changes of unstrained rabbits, either under the normal condition or fever induced by endotoxin confirms the reliability and usefulness of this system.

Hypothermia is an independent risk factor for prolonged ICU stay in coronary artery bypass surgery: an observational study

Maintenance of normothermia is a critical perioperative issue. The warming process after hypothermia tends to increase oxygen demand, which may lead to myocardial ischemia. This study explored whether hypothermia was an independent risk factor for increased morbidity and mortality in patients receiving CABG. We conducted a retrospective observational study of CABG surgeries performed from January 2018 to June 2019. The outcomes of interest were mortality, surgical site infection rate, ventilator dependent time, intensive care unit (ICU) stay, and hospitalization duration. Data from 206 patients were analysed. Hypothermic patients were taller (p = 0.012), had lower left ventricular ejection fraction (p = 0.016), and had off-pump CABG more frequently (p = 0.04). Our analysis noted no incidence of mortality within 30 days. Hypothermia was not associated with higher surgical site infection rate or longer intubation time. After adjusting for sex, age, cardiopulmonary bypass duration, left ventricular ejection fraction, and EuroSCORE II, higher EuroSCORE II (p < 0.001; odds ratio 1.2) and hypothermia upon ICU admission (p = 0.04; odds ratio 3.8) were independent risk factors for prolonged ICU stay. In addition to EuroSCORE II, hypothermia upon ICU admission was an independent risk factor for prolonged ICU stay in patients receiving elective CABG.

Validation of e-Celsius gastrointestinal telemetry system as measure of core temperature

The main objective of this study was to validate gastrointestinal measurement with the e-Celsius® system composed of an ingestible electronic capsule and a monitor. Twenty-three healthy volunteers aged 18-59 years stayed at the hospital for 24 h under fasting conditions. They were only allowed for quiet activity and were asked to keep their sleeping habits. Subjects ingested a Jonah capsule and an e-Celsius® capsule, and a rectal probe and an esophageal probe were inserted. Mean temperature measured by the e-Celsius® device was lower than that measured by Vitalsense® (-0.12 ± 0.22°C; p < 0.001) and the rectal probe (-0.11 ± 0.03°C; p = 0.003) and higher than that measured by the esophageal probe (0.17 ± 0.05; p = 0.006). Mean difference (bias) and 95% confidence intervals between temperature of e-Celsius capsule, Vitalsense Jonah capsule, esophageal probe, and rectal probe were computed using Bland and Altman procedure. The magnitude of the measurement bias is significantly greater when comparing the e-Celsius® and the Vitalsense® device pair with any other device pairs containing the esophageal probe. Amplitude of confidence interval between the e-Celsius® system and the Vitalsense® system was 0.67°C. This amplitude was significantly lower than those of the esophageal probe-e-Celsius® pairing (0.83°C; p = 0.027), of the esophageal probe-Vitalsense (0.78°C; p = 0.046) and of the esophageal probe-rectal probe (0.83°C; p = 0.002). The statistical analysis did not reveal any effect of time on the amplitude of bias, whatever the device concerned. When comparing missing data rate of the e-Celsius® system (0.23 ± 0.15%) and the Vitalsense® devices (0.70 ± 0.11%) during the whole experiment, no differences was observed (p = 0.09). The e-Celsius® system could be used when a continuous following of internal temperature is needed.

Comparisons of healthy human brain temperature predicted from biophysical modeling and measured with whole brain MR thermometry

Brain temperature is an understudied parameter relevant to brain injury and ischemia. To advance our understanding of thermal dynamics in the human brain, combined with the challenges of routine experimental measurements, a biophysical modeling framework was developed to facilitate individualized brain temperature predictions. Model-predicted brain temperatures using our fully conserved model were compared with whole brain chemical shift thermometry acquired in 30 healthy human subjects (15 male and 15 female, age range 18-36 years old). Magnetic resonance (MR) thermometry, as well as structural imaging, angiography, and venography, were acquired prospectively on a Siemens Prisma whole body 3 T MR scanner. Bland-Altman plots demonstrate agreement between model-predicted and MR-measured brain temperatures at the voxel-level. Regional variations were similar between predicted and measured temperatures (< 0.55 °C for all 10 cortical and 12 subcortical regions of interest), and subcortical white matter temperatures were higher than cortical regions. We anticipate the advancement of brain temperature as a marker of health and injury will be facilitated by a well-validated computational model which can enable predictions when experiments are not feasible.

Assessment of Alternative Body Points for Temperature Screening As Precautionary Screening During the Pandemic Using Infrared Thermometry

BACKGROUND

The recent coronavirus disease 2019 (COVID-19) pandemic, which swept across the globe in a short period, demonstrated that disease transmission management is a critical step in preventing an outbreak, as is good viral infectious disease screening. Infrared thermography (IRT) has long been considered ideal for screening body temperatures during pandemics.

METHODS

Single-centre cross-sectional study with 159 participants. Using infrared thermometry, participants were subjected to temperature measurement twice daily on various sites. This was compared to oral temperature.

RESULTS

The findings of the study revealed that infrared thermometry could be utilised as a proxy approach for screening by both individuals and medical professionals when employed at the glabella, cubits, or axillae.

CONCLUSION

 Temperature screening is implied as a prophylactic method during pandemics. Owing to contact limitations, oral thermometry cannot be used for mass screening during the pandemic. Infrared thermometry is a noncontact method of temperature screening that can readily be applied for mass temperature screening in congested venues such as airports, shopping malls, places of public convenience, and other similar locations.

Low Ambient Temperature Exposition Impairs the Accuracy of a Non-invasive Heat-Flux Thermometer

Background

Indirect core body temperature (CBT) monitoring from skin sensors is gaining attention for in-field applications thanks to non-invasivity, portability, and easy probe positioning. Among skin sensors, heat-flux devices, such as the so-called Double Sensor (DS), have demonstrated reliability under various experimental and clinical conditions. Still, their accuracy at low ambient temperatures is unknown. In this randomized cross-over trial, we tested the effects of cold temperature exposition on DS performance in tracking CBT.

Methods

Twenty-one participants were exposed to a warm (23.2 ± 0.4°C) and cold (−18.7 ± 1.0°C) room condition for 10 min, following a randomized cross-over design. The accuracy of the DS to estimate CBT in both settings was assessed by quantitative comparison with esophageal (reference) and tympanic (comparator) thermometers, using Bland–Altman and correlation analyses (Pearson’s correlation coefficient, r, and Lin’s concordance correlation coefficient, CCC).

Results

In the warm room setting, the DS showed a moderate agreement with the esophageal sensor [bias = 0.09 (−1.51; 1.69) °C, r = 0.40 (p = 0.069), CCC = 0.22 (−0.006; 0.43)] and tympanic sensor [bias = 2.74 (1.13; 4.35) °C, r = 0.54 (p < 0.05), CCC = 0.09 (0.008; 0.16)]. DS accuracy significantly deteriorated in the cold room setting, where DS temperature overestimated esophageal temperature [bias = 2.16 (−0.89; 5.22) °C, r = 0.02 (0.94), CCC = 0.002 (−0.05; 0.06)]. Previous exposition to the cold influenced temperature values measured by the DS in the warm room setting, where significant differences (p < 0.00001) in DS temperature were observed between randomization groups.

Conclusion

DS accuracy is influenced by environmental conditions and previous exposure to cold settings. These results suggest the present inadequacy of the DS device for in-field applications in low-temperature environments and advocate further technological advancements and proper sensor insulation to improve performance in these conditions.

The importance of body core temperature evaluation in balneotherapy

It is not wrong to say that there are no application standards or best practices in balneotherapy considering traditional applications. There is not enough information about how changes in body temperature, duration, and frequency of exposure to heat affect therapeutic outcomes of balneotherapeutic applications. Body core temperature (BCT) is probably the best parameter for expressing the heat load of the body and can be used to describe the causal relationship between heat exposure and its effects. There are several reasons to take BCT changes into account; for example, it can be used for individualized treatment planning, defining the consequences of thermal effects, developing disease-specific approaches, avoiding adverse effects, and designing clinical trials. The reasons why BCT changes should be considered instead of conventional measures will be discussed while explaining the effects of balneotherapy in this article, along with a discussion of BCT measurement in balneotherapy practice.

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.

[Thermoregulatory dysfunction in Parkinson's disease]

Thermoregulatory dysfunction is considered to be the least investigated among all the autonomic disorders in Parkinson disease. Pathophysiological mechanisms of this phenomena involve as central, as peripheric parts of nervous system. Dopamine deficiency in combination with peripheric autonomic dysfunction leads to temperature balance disturbance, which may be expressed by various clinical symptoms. Dopaminergic innervation of preoptic-anterior hypothalamus area plays a crucial role in thermoregulation function of central nervous system. Current thermoregulatory tests give possibility not only to reveal sudomotor and heat dissipation disorders in patients with Parkinson disease, but also to make differential diagnosis with other neurodegenerative disorders. Early detection and treatment of thermoregulatory dysfunction may improve quality of life in patients with Parkinson disease.

Smart Face Mask with an Integrated Heat Flux Sensor for Fast and Remote People's Healthcare Monitoring

The COVID-19 pandemic has highlighted a large amount of challenges to address. To combat the spread of the virus, several safety measures, such as wearing face masks, have been taken. Temperature controls at the entrance of public places to prevent the entry of virus carriers have been shown to be inefficient and inaccurate. This paper presents a smart mask that allows to monitor body temperature and breathing rate. Body temperature is measured by a non-invasive dual-heat-flux system, consisting of four sensors separated from each other with an insulating material. Breathing rate is obtained from the temperature changes within the mask, measured with a thermistor located near the nose. The system communicates by means of long-range (LoRa) backscattering, leading to a reduction in average power consumption. It is designed to establish the relative location of the smart mask from the signal received at two LoRa receivers installed inside and outside an access door. Low-cost LoRa transceivers with WiFi capabilities are used in the prototype to collect information and upload it to a server. Accuracy in body temperature measurements is consistent with measurements made with a thermistor located in the armpit. The system allows checking the correct placement of the mask based on the recorded temperatures and the breathing rate measurements. Besides, episodes of cough can be detected by sudden changes in thermistor temperature.

Accuracy of non-invasive body temperature measurement methods in critically ill patients: a prospective, bicentric, observational study

Objective: The accuracy of different non-invasive body temperature measurement methods in intensive care unit (ICU) patients is uncertain. We aimed to study the accuracy of three commonly used methods. Design: Prospective observational study. Setting: ICUs of two tertiary Australian hospitals. Participants: Critically ill patients admitted to the ICU. Interventions: Invasive (intravascular and intra-urinary bladder catheter) and non-invasive (axillary chemical dot, tympanic infrared, and temporal scanner) body temperature measurements were taken at study inclusion and every 4 hours for the following 72 hours. Main outcome measures: Accuracy of non-invasive body temperature measurement methods was assessed by the Bland-Altman approach, accounting for repeated measurements and significant explanatory variables that were identified by regression analysis. Clinical adequacy was set at limits of agreement (LoA) of 1°C compared with core temperature. Results: We studied 50 consecutive critically ill patients who were mainly admitted to the ICU after cardiac surgery. From over 375 observations, invasive core temperature (mostly pulmonary artery catheter) ranged from 33.9°C to 39°C. On average, the LoA between invasive and non-invasive measurements methods were about 3°C. The temporal scanner showed the worst performance in estimating core temperature (bias, 0.66°C; LoA, -1.23°C, +2.55°C), followed by tympanic infrared (bias, 0.44°C; LoA, -1.73°C, +2.61°C) and axillary chemical dot methods (bias, 0.32°C; LoA, -1.64°C, +2.28°C). No methods achieved clinical adequacy even accounting for significant explanatory variables. Conclusions: The axillary chemical dot, tympanic infrared and temporal scanner methods are inaccurate measures of core temperature in ICU patients. These non-invasive methods appeared unreliable for use in ICU patients.

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.

Accuracy of non-invasive body temperature measurement methods in adult patients admitted to the intensive care unit: a systematic review and meta-analysis

Objective: Non-invasive thermometers are widely used in both clinical practice and trials to estimate core temperature. We aimed to investigate their accuracy and precision in patients admitted to the intensive care unit (ICU). Study design: Systematic review and meta-analysis. Data sources: We searched MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials to identify all relevant studies from 1966 to 2017. We selected published trials that reported the accuracy and precision of non-invasive peripheral thermometers (index test) in ICU patients compared with intravascular temperature measurement (reference test). The extracted data included the study design and setting, authors, study population, devices, and body temperature measurements. Methods: Two reviewers performed the initial search, selected studies, and extracted data. Study quality was assessed using the QUADAS-2 tool. Pooled estimates of the mean bias between index and reference tests and the standard deviation of mean bias were synthesised using DerSimonian and Laird random effects meta-analyses. Results: We included 13 cohort studies (632 patients, 105 375 measurements). Axillary, tympanic infrared and zero heat flux thermometers all underestimated intravascular temperature. Only oesophageal measurements showed clinically acceptable accuracy. We found an insufficient number of studies to assess precision for any technique. Study heterogeneity was high (99-100%). Risk of bias for the index test was unclear, mostly because of no device calibration or control for confounders. Conclusions: Compared with the gold standard of intravascular temperature measurement, non-invasive peripheral thermometers have low accuracy. This makes their clinical and trial-related use in ICU patients unreliable and potentially misleading.

Is current body temperature measurement practice fit-for-purpose?

There has been a marked rise in the number of avoidable deaths in health services around the world. At the same time there has been a growing increase in antibiotic resistant so-called "superbugs." We examine here the potential role of body temperature measurement in these adverse trends. Electronic based thermometers have replaced traditional mercury (and other liquid-in-glass type) thermometers for reasons of safety rather than superiority. Electronic thermometers are in general less robust from a measurement perspective than their predecessors. We illustrate the implications of unreliable temperature measurement on the diagnosis and management of disease, including COVID-19, through statistical calculations. Since a return to mercury thermometers is both undesirable and impractical, we call for better governance in the current practice of clinical thermometry to ensure the traceability and long-term accuracy of electronic thermometers and discuss how this could be achieved.

Computer simulation study of the penetration of pulsed 30, 60 and 90 GHz radiation into the human ear

There is increasing interest in applications which use the 30 to 90 GHz frequency range, including automotive radar, 5 G cellular networks and wireless local area links. This study investigated pulsed 30–90 GHz radiation penetration into the human ear canal and tympanic membrane using computational phantoms. Modelling involved 100 ps and 20 ps pulsed excitation at three angles: direct (orthogonal), 30° anterior, and 45° superior to the ear canal. The incident power flux density (PD) estimation was normalised to the International Commission on Non-Ionizing Radiation Protection (1998) standard for general population exposure of 10 Wm⁻² and occupational exposure of 50 Wm⁻². The PD, specific absorption rate (SAR) and temperature rise within the tympanic membrane was highly dependent on the incident angle of the radiation and frequency. Using a 30 GHz pulse directed orthogonally into the ear canal, the PD in the tympanic membrane was 0.2% of the original maximal signal intensity. The corresponding PD at 90 GHz was 13.8%. A temperature rise of 0.032° C (+20%, −50%) was noted within the tympanic membrane using the equivalent of an occupational standard exposure at 90 GHz. The central area of the tympanic membrane is exposed in a preferential way and local effects on small regions cannot be excluded. The authors strongly advocate further research into the effects of radiation above 60 GHz on the structures of the ear to assist the process of setting standards.

Comprehensive Analysis of Temperature in Hospitalized Patients

BACKGROUND

Human body temperature is believed to be linked to clinical diagnoses. However, most of the available data stems from healthy individuals, with no large-scale studies addressing body temperature in the inpatient setting, which is the focus of our study.

MATERIALS AND METHODS

This is a retrospective analysis of a total of 695,107 temperature readings from 16,245 patients hospitalized over a 1-year period at a tertiary medical center, ages 0-105 years, 50% female, with rectal, monotherm, axillary, oral, temporal and tympanic measurement sites. The average temperature (T_ave) per patient and per measurement site was used in all calculations. Descriptive statistics, Student's t-test, and Pearson's correlation were used, where appropriate, with statistical significance set at P < 0.05.

RESULTS

T_ave from all measurement sites was 98.13 ± 0.48(SD)F(36.74 ± 0.27°C). T_ave varied by the site of measurement, in decreasing order highest-to-lowest being rectal, monotherm, axillary, oral, temporal, and tympanic, all of which were higher than the available reported averages for healthy subjects. T_ave decreased as patients' age increased. There was only slight and likely clinically insignificant difference between the sexes. There were differences in T_ave between the intensive care units (ICUs), listed from highest-to-lowest: Neuro ICU, Pediatric ICU, Surgical ICU, Cardiac ICU and Medical ICU. However, there was no difference between all ICU and non-ICU patients.

CONCLUSIONS

Our inpatient data demonstrate that previously identified body temperature trends among healthy subjects are preserved, to an extent, in the inpatient setting. To our knowledge, ours is the first study that evaluates the temperatures of all hospitalized patients at a large tertiary medical center.

Core temperature is not elevated at rest in people with relapsing-remitting multiple sclerosis

PURPOSE

To reassess the notion that people with multiple sclerosis (MS) do not demonstrate an elevated resting core temperature when measured using best-practice precision thermometry.

METHOD

Across two international data collection sites (Australia and USA), twenty-eight relapsing-remitting MS patients and 27 aged-matched controls (CON) were exposed to either 30 °C, 30% relative humidity (RH) (Sydney) or 25 °C, 30% RH (Dallas). Resting rectal (T_re) and esophageal (T_eso) temperature and resting oxygen consumption (VO₂) was measured in MS (n = 28) and CON (n = 27) groups who completed the 25 °C and 30 °C trials. Tympanic membrane (T_tym) temperature was measured in MS (n = 16) and CON (n = 15) groups in the 30 °C condition. A modified fatigue impact scale (MFIS) questionnaire was used to assess subjective measures of psychosocial, physical and cognitive fatigue in the 30 °C condition.

RESULTS

Irrespective of ambient temperature, no group differences were observed for T_re (MS: 37.07 ± 0.30 °C; CON: 37.18 ± 0.30 °C; P = 0.29), T_eso (MS: 36.84 ± 0.42 °C; CON: 36.92 ± 0.29 °C; P = 0.36) or resting VO₂ (MS: 3.89 ± 0.18 ml⋅kg^-1⋅min^-1; CON: 3.98 ± 0.17 ml⋅kg^-1⋅min^-1; P = 0.67). Similarly, no group differences were observed for T_tym (MS: 36.52 ± 0.38 °C; CON: 36.61 ± 0.33 °C; P = 0.55) in the 30 °C condition. Resting T_re did not correlate with subjective measures of fatigue: physical: r = -0.11, P = 0.67; cognitive: r = -0.14, P = 0.60; and psychosocial: r = 0.05, P = 0.84.

CONCLUSION

Contrary to recent reports, resting core temperature is not elevated in relapsing-remitting MS patients compared to healthy controls when measured using precision thermometry. Furthermore, no association was observed between resting T_re and any subjective measures of fatigue in a subset of participants with MS.

Cardiovascular regulation and body temperature: evidence from a nap vs. sleep deprivation randomized controlled trial

In this study we set out to understand is sleep fragmentation affects the cardiovascular regulation and circadian variability of core body temperature more or less than sleep deprivation. 50 healthy men (age 29.0+/-3.1 years; BMI 24.3+/-2.1 kg/m(2)) participated in a 3-day study that included one adaptative night and one experimental night involving randomization to: sleep deprivation (SD) and sleep fragmentation (SF). The evaluation included hemodynamic parameters, measures of the spectral analysis of heart rate and blood pressure variability, and the sensitivity of arterial baroreflex function. Core body temperature (CBT) was measured with a telemetric system. SF affects heart rate (61.9+/-5.6 vs. 56.2+/-7.6, p<0.01) and stroke index (52.7+/-11.1 vs. 59.8+/-12.2, p<0.05) with significant changes in the activity of the ANS (LF-sBP: 6.0+/-5.3 vs. 3.4+/-3.7, p<0.05; HF-sBP: 1.8+/-1.8 vs. 1.0+/-0.7, p<0.05; LF-dBP: 5.9+/-4.7 vs. 3.5+/-3.2, p<0.05) more than SD. Post hoc analysis revealed that after SD mean value of CBT from 21:30 to 06:30 was significantly higher compared to normal night's sleep and SF. In healthy men SF affects the hemodynamic and autonomic changes more than SD. Sympathetic overactivity is the proposed underlying mechanism.

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.

Circadian rhythms in bed rest: Monitoring core body temperature via heat-flux approach is superior to skin surface temperature

Continuous recordings of core body temperature (CBT) are a well-established approach in describing circadian rhythms. Given the discomfort of invasive CBT measurement techniques, the use of skin temperature recordings has been proposed as a surrogate. More recently, we proposed a heat-flux approach (the so-called Double Sensor) for monitoring CBT. Studies investigating the reliability of the heat-flux approach over a 24-hour period, as well as comparisons with skin temperature recordings, are however lacking. The first aim of the study was therefore to compare rectal, skin, and heat-flux temperature recordings for monitoring circadian rhythm. In addition, to assess the optimal placement of sensor probes, we also investigated the effect of different anatomical measurement sites, i.e. sensor probes positioned at the forehead vs. the sternum. Data were collected as part of the Berlin BedRest study (BBR2-2) under controlled, standardized, and thermoneutral conditions. 24-hours temperature data of seven healthy males were collected after 50 days of -6° head-down tilt bed-rest. Mean Pearson correlation coefficients indicated a high association between rectal and forehead temperature recordings (r > 0.80 for skin and Double Sensor). In contrast, only a poor to moderate relationship was observed for sensors positioned at the sternum (r = -0.02 and r = 0.52 for skin and Double Sensor, respectively). Cross-correlation analyses further confirmed the feasibility of the forehead as a preferred monitoring site. The phase difference between forehead Double Sensor and rectal recordings was not statistically different from zero (p = 0.313), and was significantly smaller than the phase difference between forehead skin and rectal temperatures (p = 0.016). These findings were substantiated by cosinor analyses, revealing significant differences for mesor, amplitude, and acrophase between rectal and forehead skin temperature recordings, but not between forehead Double Sensor and rectal temperature measurements. Finally, Bland-Altman analysis indicated narrower limits of agreement for rhythm parameters between rectal and Double Sensor measurements compared to between rectal and skin recordings, irrespective of the measurement site (i.e. forehead, sternum). Based on these data we conclude that (1) Double Sensor recordings are significantly superior to skin temperature measurements for non-invasively assessing the circadian rhythm of rectal temperature, and (2) temperature rhythms from the sternum are less reliable than from the forehead. We suggest that forehead Double Sensor recordings may provide a surrogate for rectal temperature in circadian rhythm research, where constant routine protocols are applied. Future studies will be needed to assess the sensor's ecological validity outside the laboratory under changing environmental and physiological conditions.

Temperature Measurement in Critical Care Adults: A Comparison of Thermometry and Measurement Routes

Purpose. To describe within- and between-subject mean differences between and among temperature sites (oral, axilla, PA) and instruments.

Methods. A convenience sample (N = 35) of volunteering, adult (18 years), 1st-day postcardiac surgery inpatients was obtained. Temperature-sensing instruments included Geratherm DataTherm and SolarTherm, and Abbott Opticath fiber optic PA catheters. For 21 min, simultaneous temperature readings (°C) at 4 temperature sites with 3 thermometry devices were monitored.

Results. Mean difference at 21 min PA and between DataTherm axilla and PA = 0.72°C (SD 0.30); between PA and SolarTherm oral = 0.62°C (SD 0.34); and between PA and SolarTherm axilla = 0.46°C (SD 0.16). Temperature levels were not a factor relative to difference scores between study and reference devices.

Conclusions. Both test devices, SolarTherm (an intermittent-use device) and DataTherm (a temperature-monitoring device), performed well, and correlated strongly with PA temperature assesments.

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.

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.

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.

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.

Accidental cold-related injury leading to hospitalization in northern Sweden: an eight-year retrospective analysis

BACKGROUND

Cold injuries are rare but important causes of hospitalization. We aimed to identify the magnitude of cold injury hospitalization, and assess causes, associated factors and treatment routines in a subarctic region.

METHODS

In this retrospective analysis of hospital records from the 4 northernmost counties in Sweden, cases from 2000-2007 were identified from the hospital registry by diagnosis codes for accidental hypothermia, frostbite, and cold-water drowning. Results were analyzed for pre-hospital site events, clinical events in-hospital, and complications observed with mild (temperature 34.9 - 32°C), moderate (31.9 - 28°C) and severe (<28°C), hypothermia as well as for frostbite and cold-water drowning.

RESULTS

From the 362 cases, average annual incidences for hypothermia, frostbite, and cold-water drowning were estimated to be 3.4/100,000, 1.5/100,000, and 0.8/100,000 inhabitants, respectively. Annual frequencies for hypothermia hospitalizations increased by approximately 3 cases/year during the study period. Twenty percent of the hypothermia cases were mild, 40% moderate, and 24% severe. For 12%, the lowest documented core temperature was 35°C or higher, for 4% there was no temperature documented. Body core temperature was seldom measured in pre-hospital locations. Of 362 cold injury admissions, 17 (5%) died in hospital related to their injuries. Associated co-factors and co-morbidities included ethanol consumption, dementia, and psychiatric diagnosis.

CONCLUSIONS

The incidence of accidental hypothermia seems to be increasing in this studied sub-arctic region. Likely associated factors are recognized (ethanol intake, dementia, and psychiatric diagnosis).

Altered circadian rhythmicity in patients in the ICU

BACKGROUND

Patients in the ICU are thought to have abnormal circadian rhythms, but quantitative data are lacking.

METHODS

To investigate circadian rhythms in the ICU, we studied core body temperatures over a 48-h period in 21 patients (59 ± 11 years of age; eight men and 13 women).

RESULTS

The circadian phase position for 17 of the 21 patients fell outside the published range associated with morningness/eveningness, which determines the normative range for variability among healthy normal subjects. In 10 patients, the circadian phase position fell earlier than the normative range; in seven patients, the circadian phase position fell later than the normative range. The mean ± SD of circadian displacement in either direction (advance or delay) was 4.44 ± 3.54 h. There was no significant day-to-day variation of the 24-h temperature profile within each patient. Stepwise linear regression was performed to determine if age, sex, APACHE (Acute Physiology and Chronic Health Evaluation) III score, or day in the ICU could predict the patient-specific magnitude of circadian displacement. The APACHE III score was found to be significantly predictive of circadian displacement.

CONCLUSIONS

The findings indicate that circadian rhythms are present but altered in patients in the ICU, with the degree of circadian abnormality correlating with severity of illness.

Comparison of three different thermometers in evaluating the body temperature of healthy young adult individuals

The aim of this study was to compare the measurement values obtained with a non-contact infrared thermometer, a tympanic thermometer and a chemical dot thermometer. The research population was composed of students studying in two departments of a university in Ankara. A total of 452 students who fit the inclusion criteria of the study and volunteered to participate were included in the sample. Body temperature measurements with different thermometers were performed by the same researcher at the same room temperature. Data were analyzed in a computerized environment by SPSS 15.0 statistical program pack and Bland-Altman graph. Mean age of healthy young adults participating in the study was 19.66 ± 0.94, and 55.1% of them were female. The agreement limits for non-contact infrared and chemical dot was between -1.30 and 0.32°C; for non-contact infrared and tympanic was between -1.26 and 0.13°C; and for chemical dot and tympanic -0.89 and 0.74°C. It was determined that, although the measurement values of the tympanic membrane and chemical dot thermometers conformed with each other, the conformity of the non-contact infrared thermometer was weak.

Infection in neutropenic patients with cancer

Neutropenic fever sepsis syndromes are common among patients with cancer who are receiving intensive cytotoxic systemic therapy. Recognition of the syndromes and timely initial antibacterial therapy is critical for survival and treatment success. Outcomes are linked to myeloid reconstitution and recovery from neutropenia, control of active comorbidities, and appropriate treatment of the infections that underlie the sepsis syndrome. Hematologists and oncologists must be clear about the prognosis and treatment goals to work effectively with critical care physicians toward the best outcomes for patients with cancer who develop neutropenic sepsis syndromes.

Cold-induced vasodilatation response in the fingers at 4 different water temperatures

We evaluated the cold-induced vasodilatation (CIVD) response at 4 different water temperatures. Nine healthy young male subjects immersed their right hands in 35 °C water for 5 min, and immediately thereafter for 30 min in a bath maintained at either 5, 8, 10, or 15 °C. The responses of finger skin temperatures, subjective ratings of thermal comfort and temperature sensation scores were compared between the 4 immersion trials. The number of subjects who exhibited a CIVD response was higher during immersion of the hand in 5 and 8 °C (100%) compared with 10 and 15 °C water (87.5% and 37.5%, respectively). The CIVD temperature amplitude was 4.2 ± 2.6, 3.4 ± 2.0, 2.1 ± 1.6, and 2.8 ± 2.0 °C at 5, 8, 10, and 15 °C trials, respectively; higher in 5 and 8 °C compared with 10 and 15 °C water (p = 0.003). No differences in CIVD were found between the 5 and 8 °C immersions. However, during immersion in 5 °C, subjects felt “uncomfortable” while in the other trials felt “slightly uncomfortable” (p = 0.005). The temperature sensation score was “cold” for 5 °C and “cool” for the other trials, but no statistical differences were observed. Immersion of the hand in 8 °C elicits a CIVD response of similar magnitude as immersion in 5 °C, but with less thermal discomfort.

Emergency department rectal temperatures in over 10 years: A retrospective observational study

BACKGROUND

Fever in patients can provide an important clue to the etiology of a patient's symptoms. Non-invasive temperature sites (oral, axillary, temporal) may be insensitive due to a variety of factors. This has not been well studied in adult emergency department patients. To determine whether emergency department triage temperatures detected fever adequately when compared to a rectal temperature.

METHODS

A retrospective chart review was made of 27 130 adult patients in a high volume, urban emergency department over an eight-year period who received first a non-rectal triage temperature and then a subsequent rectal temperature.

RESULTS

The mean difference in temperatures between the initial temperature and the rectal temperature was 1.3 °F (P<0.001), with 25.9% of the patients having higher rectal temperatures ≥2 °F, and 5.0% having higher rectal temperatures ≥4 °F. The mean difference among the patients who received oral, axillary, and temporal temperatures was 1.2 °F (P<0.001), 1.8 °F (P<0.001), and 1.2 °F (P<0.001) respectively. About 18.1% of the patients were initially afebrile and found to be febrile by rectal temperature, with an average difference of 2.5 °F (P<0.001). These patients had a higher rate of admission (61.4%, P<0.005), and were more likely to be admitted to the hospital for a higher level of care, such as an intensive care unit, when compared with the full cohort (12.5% vs. 5.8%, P<0.005).

CONCLUSIONS

There are significant differences between rectal temperatures and non-invasive triage temperatures in this emergency department cohort. In almost one in five patients, fever was missed by triage temperature.

Comparability of tympanic and oral mercury thermometers at high ambient temperatures

Background

Body temperature can be measured in seconds with tympanic thermometers as opposed to minutes with mercury ones. The aim of this study was to compare tympanic and oral mercury thermometer measurements under high ambient field temperatures.

Results

Tympanic temperature (measured thrice by 3 operators) was compared to oral temperature measured once with a mercury-in-glass thermometer in 201 patients (aged ≥5 years), on the Thai-Myanmar border. Ambient temperature was measured with an electronic thermo-hygrometer. Participants had a mean [min-max] age of 27 [5–60] years and 42% (84) were febrile by oral thermometer. The mean difference in the mercury and tympanic temperature measurement for all observers/devices was 0.09 (95%CI 0.07-0.12)°C and intra-class correlation for repeat tympanic measurements was high (≥0.97) for each observer. Deviations in tympanic temperatures were not related to ambient temperature.

Conclusion

Clinically significant differences were not observed between oral and tympanic temperature measurements at high ambient temperatures in a rural tropical setting.

A comparison of different methods of temperature measurements in sick newborns

We aimed to compare the accuracy of digital axillary thermometer (DAT), rectal glass mercury thermometer (RGMT), infrared tympanic thermometer (ITT) and infrared forehead skin thermometer (IFST) measurements with traditional axillary glass mercury thermometer (AGMT) for intermittent temperature measurement in sick newborns. A prospective, descriptive and comparative study in which five different types of thermometer readings were performed sequentially for 3 days. A total of 1989 measurements were collected from 663 newborns. DAT and ITT measurements correlated most closely to AGMT (r = 0.94). The correlation coefficent for IFST and RGMT were 0.74 and 0.87, respectively. The mean differences for DAT, ITT, RGMT and IFST were +0.02°C, +0.03°C, +0.25°C and +0.55°C, respectively. There were not any clinical differences (defined as a mean difference of 0.2°C) between both mean AGMT&DAT and AGMT&ITT measurements. Our study suggests that tympanic thermometer measurement could be used as an acceptable and practical method for sick newborn in neonatal units.

Protective facemask impact on human thermoregulation: an overview

The use of protective facemasks (PFMs) negatively impacts respiratory and dermal mechanisms of human thermoregulation through impairment of convection, evaporation, and radiation processes. The relatively minor reported increases in core temperature directly attributable to the wearing of PFMs suggest that associated perceptions of increased body temperature may have a significant psychological component or that regional or global brain temperature changes are involved. Modifications in PFM structure, components, and materials might allow for improved heat dissipation and enhanced compliance with use.

Evidence-based guidelines for empirical therapy of neutropenic fever in Korea

Neutrophils play an important role in immunological function. Neutropenic patients are vulnerable to infection, and except fever is present, inflammatory reactions are scarce in many cases. Additionally, because infections can worsen rapidly, early evaluation and treatments are especially important in febrile neutropenic patients. In cases in which febrile neutropenia is anticipated due to anticancer chemotherapy, antibiotic prophylaxis can be used, based on the risk of infection. Antifungal prophylaxis may also be considered if long-term neutropenia or mucosal damage is expected. When fever is observed in patients suspected to have neutropenia, an adequate physical examination and blood and sputum cultures should be performed. Initial antibiotics should be chosen by considering the risk of complications following the infection; if the risk is low, oral antibiotics can be used. For initial intravenous antibiotics, monotherapy with a broad-spectrum antibiotic or combination therapy with two antibiotics is recommended. At 3-5 days after beginning the initial antibiotic therapy, the condition of the patient is assessed again to determine whether the fever has subsided or symptoms have worsened. If the patient's condition has improved, intravenous antibiotics can be replaced with oral antibiotics; if the condition has deteriorated, a change of antibiotics or addition of antifungal agents should be considered. If the causative microorganism is identified, initial antimicrobial or antifungal agents should be changed accordingly. When the cause is not detected, the initial agents should continue to be used until the neutrophil count recovers.

Measurement of body temperature in adult patients: comparative study of accuracy, reliability and validity of different devices

BACKGROUND AND AIMS

We compared a range of alternative devices with core body temperature measured at the pulmonary artery to identify the most valid and reliable instrument for measuring temperature in routine conditions in health services.

METHODS

201 patients from the intensive care unit of the Candelaria University Hospital, Canary Islands, admitted to hospital between April 2006 and July 2007. All patients (or their families) gave informed consent. Readings from gallium-in-glass, reactive strip and digital in axilla, infra-red ear and frontal thermometers were compared with the pulmonary artery core temperature simultaneously. External factors suspected of having an influence on the differences were explored. The cut-off point readings for each thermometer were fixed for the maximum negative predictive value in comparison with the core temperature. The validity, reliability, accuracy, external influence, the waste they generated, ease of use, speed, durability, security, comfort and cost of each thermometer was evaluated. An ad hoc overall valuation score was obtained from these parameters for each instrument.

RESULTS

For an error of ± 0.2°C and concordance with respect to fever, the gallium-in-glass thermometer gave the best results. The largest area under the receiver operating characteristic (ROC) curve is obtained by the digital axillar thermometer with probe (0.988 ± 0.007). The minimum difference between readings was given by the infrared ear thermometer, in comparison with the core temperature (-0.1 ± 0.3°C). Age, weight, level of conscience, male sex, environmental temperature and vaso-constrictor medication increases the difference in the readings and fever treatment reduces it, although this is not the same for all thermometers. The compact digital axillar thermometer and the digital thermometer with probe obtained the highest overall valuation score.

CONCLUSION

If we only evaluate the aspects of validity, reliability, accuracy and external influence, the best thermometer would be the gallium-in-glass after 12 min. The gallium-in-glass thermometer is less accurate after only 5 min in comparison with the reading taken after being placed for 12 min. If we add the evaluation of waste production, ease-of-use, speed, durability, security, patient comfort and costs, the thermometers that obtain the highest score are the compact digital and digital with probe in right axilla.

Core-temperature sensor ingestion timing and measurement variability

CONTEXT

Telemetric core-temperature monitoring is becoming more widely used as a noninvasive means of monitoring core temperature during athletic events.

OBJECTIVE

To determine the effects of sensor ingestion timing on serial measures of core temperature during continuous exercise.

DESIGN

Crossover study.

SETTING

Outdoor dirt track at an average ambient temperature of 4.4°C ± 4.1°C and relative humidity of 74.1% ± 11.0%.

PATIENTS OR OTHER PARTICIPANTS

Seven healthy, active participants (3 men, 4 women; age  =  27.0 ± 7.5 years, height  =  172.9 ± 6.8 cm, body mass  =  67.5 ± 6.1 kg, percentage body fat  =  12.7% ± 6.9%, peak oxygen uptake [Vo(2peak)]  =  54.4 ± 6.9 mL•kg⁻¹•min⁻¹) completed the study.

INTERVENTION(S)

Participants completed a 45-minute exercise trial at approximately 70% Vo(2peak). They consumed core-temperature sensors at 24 hours (P1) and 40 minutes (P2) before exercise.

MAIN OUTCOME MEASURE(S)

Core temperature was recorded continuously (1-minute intervals) using a wireless data logger worn by the participants. All data were analyzed using a 2-way repeated-measures analysis of variance (trial × time), Pearson product moment correlation, and Bland-Altman plot.

RESULTS

Fifteen comparisons were made between P1 and P2. The main effect of time indicated an increase in core temperature compared with the initial temperature. However, we did not find a main effect for trial or a trial × time interaction, indicating no differences in core temperature between the sensors (P1  =  38.3°C ± 0.2°C, P2  =  38.3°C ± 0.4°C).

CONCLUSIONS

We found no differences in the temperature recordings between the 2 sensors. These results suggest that assumed sensor location (upper or lower gastrointestinal tract) does not appreciably alter the transmission of reliable and repeatable measures of core temperature during continuous running in the cold.

[Prospective study of tympanic temperature in patients undergoing haemopoietic transplant]

OBJECTIVE

During haemopoietic transplant, the patient may be affected by body temperature variations which may be associated with potential or real complications. In this clinical context and due unavoidable changes in values, we established as objectives; to check whether the reference values stated in the literature are adapted to our clinical reality, and to check the possible influence of mucositis in the determination of the tympanic temperature.

METHOD

A prospective descriptive study was performed on 776 cases in the Haemopoietic Transplant Unit of the Hospital Morales Meseguer, of Murcia, from the 13 March to the 15 September of 2002, in patients undergoing stem cells transplant. A 95% confidence level has been applied to the Chi(2) test in the statistical analysis.

RESULTS

The mean tympanic temperature obtained in the right ear was 37.4 degrees C, whereas the axillary mean was 36.54 degrees C. Grade II mucositis was found to be the main associated variable.

CONCLUSIONS

Some authors suggest that the tympanic temperature, despite the speed, reliability and lack of impact on the environment, is subject to many uncertainties that can lead to diagnostic errors and subsequent clinical decision. In our study, the reference values have differed from those previously obtained due to, among other things, them being values associated to healthy people, whereas in our case, the determinations were made in convalescents with mucositis. Therefore, given that the clinical condition affects the reliability of the tympanic readings, this method is not applicable in our clinical care.

Detection and management of hypothermia at a large outdoor endurance event in the United kingdom

OBJECTIVE

Optimum detection of hypothermia in athletes during outdoor exposure events remains controversial. The aims of this study were firstly to assess whether temperature readings affected competitor discharge from the treatment station and secondly to assess agreement between oral and tympanic thermometer measurements.

METHODS

All competitors treated for symptomatic hypothermia at an outdoor endurance event in the United Kingdom during January 2009 were included. Temperature readings were taken using oral (Digitemp digital oral thermometer) and tympanic (Braun Thermoscan IRT 4520 ExacTemp) thermometers, with a temperature <35 degrees C classifying hypothermia.

RESULTS

From 4700 competitors, 64 (1.4%) were treated for symptomatic hypothermia. Of these, 92% were male, the mean age was 26 years, and the mean treatment time was 25 minutes. There was no severe/life-threatening hypothermia, and no competitors required transport to a hospital for hypothermia. At discharge, 19% of competitors were still classed as hypothermic in the oral group and 28% in the tympanic group, despite competitors only being discharged when no longer symptomatic. Oral readings at discharge were significantly lower than tympanic readings (33.8 degrees C [95% CI, 33.2 degrees C to 34.5 degrees C] vs 35.0 degrees C [95% CI, 34.6 degrees C to 35.3 degrees C], respectively, P = .003).

CONCLUSIONS

The use of thermometers had a limited role in discharging competitors at this event, who were apparently safely discharged when no longer symptomatic. Treating clinicians and the thermometers did not always agree on whether a patient was hypothermic or not. Oral and tympanic thermometers had poor agreement. Routine thermometer readings at future events may be unnecessary, although screening competitors of concern will remain useful.

Current practice and knowledge of nurses regarding patient temperature measurement

BACKGROUND

The measurement of patient temperature by nursing staff is a common activity. In recent years this area of practice has been largely under-investigated despite the introduction of new technologies into clinical practice, such as infrared tympanic thermometry (IRTT).

STUDY AIM

To investigate current practice in clinical temperature measurement in general, and the use of IRTT in particular by nursing staff.

SAMPLE AND METHODS

139 nursing staff from a general hospital in the UK were surveyed via a self-administered questionnaire.

MAIN FINDINGS AND CONCLUSIONS

The group most involved in temperature measurement was characterized as nursing auxiliary grades with the fewest years of experience. IRTT was the most frequently-used method for measuring patient temperatures, with high perceived accuracy, reliability, ease of use and acceptability to patients. A poor level of understanding and training in the use of IRTT was revealed across all clinical grades. Recommendations for future investigations are made.

Towards a non-invasive interictal application of hypothermia for treating seizures: a feasibility and pilot study

OBJECTIVES

To evaluate the feasibility and safety of head-neck cooling in conscious normal volunteers (10) and patients with medically refractory epilepsy (5) without causing shivering.

PATIENTS AND METHODS

We used a non-invasive head-neck cooling system (CoolSystems Inc., Lincoln, CA, USA). The tympanic temperature (TT) and intestinal temperature (IT) were measured as two measurements of 'core temperature' (CT), and multi-site external temperatures, several physiologic variables and EEG were monitored. Seizure counts over 4-week precooling, treatment and follow-up phases were compared.

RESULTS

All 15 participants completed all the cooling sessions without significant complaints. At the end of 60 min of cooling, scalp temperature fell on average by 12.2 degrees C (P < 0.001), TT by 1.67 degrees C (P < 0.001), and IT by 0.12 degrees C (P = NS). Average weekly seizure frequency decreased from 2.7 to 1.7 events per patient per week (MANOVA: P < 0.05).

CONCLUSIONS

Non-invasive head-neck cooling is safe and well-tolerated. Initial pilot data in patients suggest that additional therapeutic studies are warranted.