Deep Body Temperature Measurement Research Articles

Current status of active cooling, deep body temperature measurement, and face mask wearing in heat stroke and heat exhaustion patients in Japan: a nationwide observational study based on the Heatstroke STUDY 2020 and 2021.

The study aimed to determine the current status of face mask use, deep body temperature measurement, and active cooling in patients suffering from heatstroke and heat exhaustion in Japan. This was a prospective, observational, multicenter study using data from the Heatstroke STUDY 2020-2021, a nationwide periodical registry of heat stroke and heat exhaustion patients. Based on the Bouchama heatstroke criteria, we classified the patients into two groups: severe and mild-to-moderate. We compared the outcomes between the two groups and reclassified them into two subgroups according to the severity of the illness, deep body temperature measurements, and face mask use. Cramer's V was used to determine the effect sizes for a comparison between groups. Almost all patients in this study were categorized as having degree III based on the Japanese Association for Acute Medicine heatstroke criteria (JAAM-HS). However, the severe group was significantly worse than the mild-to-moderate group in outcomes like in-hospital death and modified Rankin Scale scores, when discharged. Heatstrokes had significantly higher rates of active cooling and lower mortality rates than heatstroke-like illnesses. Patients using face masks often use them during labor, sports, and other exertions, had less severe conditions, and were less likely to be young male individuals. It is suggested that severe cases require a more detailed classification of degree III in the JAAM-HS criteria, and not measuring deep body temperature could have been a factor in the nonperformance of active cooling and worse outcomes.

Agreement of telemetric temperature capsules ingested 48 hours apart

Telemetric temperature capsules are frequently utilized to measure deep body temperature. Whereas most methods to measure temperature are conducted at a single site (e.g., rectal temperature), the location of ingested telemetry capsules varies. If distinct regions of the gastrointestinal tract have different temperatures, the measurements obtained using telemetry capsules will vary accordingly. This study examined the agreement of two telemetric temperature capsules in fifty-seven Army Ranger School students ingested 64 and 16 h before a cool weather waterborne movement. Twenty-one subjects (37%) (age: 25 ± 4, weight: 81±7 kg) retained both capsules. Subjects completed activities that could increase (e.g. exercise) and decrease (e.g. cold water immersion) body temperature. Agreement between the two capsules was assessed through concordance and Bland Altman analysis using a linear mixed model. Bias between the two capsules was low (0.01 °C, SE = 0.03, before a neck-deep immersion river crossing and −0.09 °C, SE = 0.08, after the river crossing), but there were large differences in the variance components (0.044 vs 0.155 total variance for the pre-crossing vs the post-crossing data). The 95% Limits of Agreement indicate that discordance between the two capsules was lower before the river crossing (−0.40 to +0.42 °C) than after (−0.86 to +0.68 °C). In summary, this study examined telemetry capsule agreement with more time between capsule ingestion (48 h) in a larger sample size than most previous studies on the topic, and found notable (95% LoA>0.4 °C) variability between the two capsules which was exacerbated after crossing a cold river. Differences in gastrointestinal location of telemetry capsules can introduce variability into the measurement of deep body temperature due to regional temperature differences. This variability may be acceptable for some study designs, but unacceptable when small changes in temperature are important to detect. If the convenience of telemetric temperature capsules is desired, an alternative is to use the capsule as a rectal suppository.

A Study on the measurement accuracy of deep body temperature measurement by dual heat flow method

A Study on the measurement accuracy of deep body temperature measurement by dual heat flow method

A Comparative Study of Two Ambulatory Core Temperature Assessment Methods

Background. Given the need to identify reliable non-invasive solutions for core temperature ambulatory monitoring, the purpose of this study was to evaluate the performance of zero-heat-flux (ZHF) temperature sensor on the forehead (TCOzhf) by comparing it with intestinal temperature (TCOpill) in different ambient and physiological conditions.Methods. Seven trained male subjects were followed during a 45-min rest period (STA) and a 25-min self-regulated cycling exercise performed in neutral (TMP, 22.8 °C) and hot (HOT, 38.5 °C) ambient temperature.Results.TCOzhf values differed from TCOpill of −0.23 ± 0.13 in STA, 0.15 ± 0.30 °C in TMP and 0.28±0.38 °C in HOT. The 95% limits of agreement showed an acceptable bias between TCOzhf and TCOpill in STA (±0.26 °C), but not in TMP and HOT (±0.60 and ±0.75 °C).Conclusion. The non-invasive ZHF sensor gave an accurate estimation of TCOpill in steady state but not during exercise. However, complementary results let suppose that ZHF performance is not affected by ambient conditions and could be a relevant alternative for deep body temperature measurement during whole-body heat stress.

A vascular mechanism to explain thermally mediated variations in deep-body cooling rates during the immersion of profoundly hyperthermic individuals.

What is the central question of this study? Does the cold-water immersion (14°C) of profoundly hyperthermic individuals induce reductions in cutaneous and limb blood flow of sufficient magnitude to impair heat loss relative to the size of the thermal gradient? What is the main finding and its importance? The temperate-water cooling (26°C) of profoundly hyperthermic individuals was found to be rapid and reproducible. A vascular mechanism accounted for that outcome, with temperature-dependent differences in cutaneous and limb blood flows observed during cooling. Decisions relating to cooling strategies must be based upon deep-body temperature measurements that have response dynamics consistent with the urgency for cooling. Physiologically trivial time differences for cooling the intrathoracic viscera of hyperthermic individuals have been reported between cold- and temperate-water immersion treatments. One explanation for that observation is reduced convective heat delivery to the skin during cold immersion, and this study was designed to test both the validity of that observation, and its underlying hypothesis. Eight healthy men participated in four head-out water immersions: two when normothermic, and two after exercise-induced, moderate-to-profound hyperthermia. Two water temperatures were used within each thermal state: temperate (26°C) and cold (14°C). Tissue temperatures were measured at three deep-body sites (oesophagus, auditory canal and rectum) and eight skin surfaces, with cutaneous vascular responses simultaneously evaluated from both forearms (laser-Doppler flowmetry and venous-occlusion plethysmography). During the cold immersion of normothermic individuals, oesophageal temperature decreased relative to baseline (-0.31°C over 20min; P<0.05), whilst rectal temperature increased (0.20°C; P<0.05). When rendered hyperthermic, oesophageal (-0.75°C) and rectal temperatures decreased (-0.05°C) during the transition period (<8.5min, mostly in air at 22°C), with the former dropping to 37.5°C only 54s faster when immersed in cold rather than in temperate water (P<0.05). Minimal cutaneous vasoconstriction occurred during either normothermic immersion, whereas pronounced constriction was evident during both immersions when subjects were hyperthermic, with the colder water eliciting a greater vascular response (P<0.05). It was concluded that the rapid intrathoracic cooling of asymptomatic, hyperthermic individuals in temperate water was a reproducible phenomenon, with slower than expected cooling in cold water brought about by stronger cutaneous vasoconstriction that reduced convective heat delivery to the periphery.

Novel Zero-Heat-Flux Deep Body Temperature Measurement in Lower Extremity Vascular and Cardiac Surgery.

The aim of this study was to compare deep body temperature obtained using a novel noninvasive continuous zero-heat-flux temperature measurement system with core temperatures obtained using conventional methods. A prospective, observational study. Operating room of a university hospital. The study comprised 15 patients undergoing vascular surgery of the lower extremities and 15 patients undergoing cardiac surgery with cardiopulmonary bypass. Zero-heat-flux thermometry on the forehead and standard core temperature measurements. Body temperature was measured using a new thermometry system (SpotOn; 3M, St. Paul, MN) on the forehead and with conventional methods in the esophagus during vascular surgery (n = 15), and in the nasopharynx and pulmonary artery during cardiac surgery (n = 15). The agreement between SpotOn and the conventional methods was assessed using the Bland-Altman random-effects approach for repeated measures. The mean difference between SpotOn and the esophageal temperature during vascular surgery was+0.08°C (95% limit of agreement -0.25 to+0.40°C). During cardiac surgery, during off CPB, the mean difference between SpotOn and the pulmonary arterial temperature was -0.05°C (95% limits of agreement -0.56 to+0.47°C). Throughout cardiac surgery (on and off CPB), the mean difference between SpotOn and the nasopharyngeal temperature was -0.12°C (95% limits of agreement -0.94 to+0.71°C). Poor agreement between the SpotOn and nasopharyngeal temperatures was detected in hypothermia below approximately 32°C. According to this preliminary study, the deep body temperature measured using the zero-heat-flux system was in good agreement with standard core temperatures during lower extremity vascular and cardiac surgery. However, agreement was questionable during hypothermia below 32°C.

Evaluation of structural and thermophysical effects on the measurement accuracy of deep body thermometers based on dual-heat-flux method

To help pave a path toward the practical use of continuous unconstrained noninvasive deep body temperature measurement, this study aims to evaluate the structural and thermophysical effects on measurement accuracy for the dual-heat-flux method (DHFM). By considering the thermometer's height, radius, conductivity, density and specific heat as variables affecting the accuracy of DHFM measurement, we investigated the relationship between those variables and accuracy using 3-D models based on finite element method. The results of our simulation study show that accuracy is proportional to the radius but inversely proportional to the thickness of the thermometer when the radius is less than 30.0mm, and is also inversely proportional to the heat conductivity of the heat insulator inside the thermometer. The insights from this study would help to build a guideline for design, fabrication and optimization of DHFM-based thermometers, as well as their practical use.

Theoretical study on the inverse modeling of deep body temperature measurement

We evaluated the theoretical aspects of monitoring the deep body temperature distribution with the inverse modeling method. A two-dimensional model was built based on anatomical structure to simulate the human abdomen. By integrating biophysical and physiological information, the deep body temperature distribution was estimated from cutaneous surface temperature measurements using an inverse quasilinear method. Simulations were conducted with and without the heat effect of blood perfusion in the muscle and skin layers. The results of the simulations showed consistently that the noise characteristics and arrangement of the temperature sensors were the major factors affecting the accuracy of the inverse solution. With temperature sensors of 0.05 °C systematic error and an optimized 16-sensor arrangement, the inverse method could estimate the deep body temperature distribution with an average absolute error of less than 0.20 °C. The results of this theoretical study suggest that it is possible to reconstruct the deep body temperature distribution with the inverse method and that this approach merits further investigation.

Is Oral Temperature an Accurate Measurement of Deep Body Temperature? A Systematic Review

Oral temperature might not be a valid method to assess core body temperature. However, many clinicians, including athletic trainers, use it rather than criterion standard methods, such as rectal thermometry. To critically evaluate original research addressing the validity of using oral temperature as a measurement of core body temperature during periods of rest and changing core temperature. In July 2010, we searched the electronic databases PubMed, Scopus, Cumulative Index to Nursing and Allied Health Literature (CINAHL), SPORTDiscus, Academic Search Premier, and the Cochrane Library for the following concepts: core body temperature, oral, and thermometers. Controlled vocabulary was used, when available, as well as key words and variations of those key words. The search was limited to articles focusing on temperature readings and studies involving human participants. Original research was reviewed using the Physiotherapy Evidence Database (PEDro). Sixteen studies met the inclusion criteria and subsequently were evaluated by 2 independent reviewers. All 16 were included in the review because they met the minimal PEDro score of 4 points (of 10 possible points), with all but 2 scoring 5 points. A critical review of these studies indicated a disparity between oral and criterion standard temperature methods (eg, rectal and esophageal) specifically as the temperature increased. The difference was -0.50°C ± 0.31°C at rest and -0.58°C ± 0.75°C during a nonsteady state. Evidence suggests that, regardless of whether the assessment is recorded at rest or during periods of changing core temperature, oral temperature is an unsuitable diagnostic tool for determining body temperature because many measures demonstrated differences greater than the predetermined validity threshold of 0.27°C (0.5°F). In addition, the differences were greatest at the highest rectal temperatures. Oral temperature cannot accurately reflect core body temperature, probably because it is influenced by factors such as ambient air temperature, probe placement, and ingestion of fluids. Any reliance on oral temperature in an emergency, such as exertional heat stroke, might grossly underestimate temperature and delay proper diagnosis and treatment.

Development of a new method for the noninvasive measurement of deep body temperature without a heater

The conventional zero-heat-flow thermometer, which measures the deep body temperature from the skin surface, is widely used at present. However, this thermometer requires considerable electricity to power the electric heater that compensates for heat loss from the probe; thus, AC power is indispensable for its use. Therefore, this conventional thermometer is inconvenient for unconstrained monitoring. We have developed a new dual-heat-flux method that can measure the deep body temperature from the skin surface without a heater. Our method is convenient for unconstrained and long-term measurement because the instrument is driven by a battery and its design promotes energy conservation. Its probe consists of dual-heat-flow channels with different thermal resistances, and each heat-flow-channel has a pair of IC sensors attached on its top and bottom. The average deep body temperature measurements taken using both the dual-heat-flux and then the zero-heat-flow thermometers from the foreheads of 17 healthy subjects were 37.08 °C and 37.02 °C, respectively. In addition, the correlation coefficient between the values obtained by the 2 methods was 0.970 ( p < 0.001). These results show that our method can be used for monitoring the deep body temperature as accurately as the conventional method, and it overcomes the disadvantage of the necessity of AC power supply.

Deep temperature monitoring using a zero-heat-flow method.

of perforation of the rectum by the probe, especially in children [8]. In 1971, Fox and Solman [9,10] invented a noninvasive deep temperature thermometer using a zero-heat-flow method. This thermometer enables measurement of the deep body temperature indirectly from the intact skin surface. The technique of deep temperature monitoring using this thermometer has been improved, mainly by Togawa’s group and Terumo Co. [11,12]. Monitoring of deep body temperature, especially from the forehead, is now widely used in cardiac surgery in Japan. Deep temperature monitoring has also been used in intensive care units [13] and for monitoring of circulatory failure [14]. The equipment used for deep temperature monitoring has recently been improved, and the disadvantages of the conventional device have been overcome. Here, we review the principle of deep body temperature measurement, its characteristic features and clinical applications, and improvement in the equipment used for measurement.

A method for measuring deep body temperature in avian embryos

Two methods for the measurement of deep body temperature in chicken embryos (21st day of incubation) were compared: temperature of the allantoic fluid near the embryo ( T af) and colonic temperature ( T c). When ambient temperature ( T a) was raised to 40.5°C T af increased shortly after and parallel to T a while T c was kept nearly constant for more than 40 min after the beginning T a-rise. Measuring T c has the advantage of being the only possibility to get information about the embryo’s deep body temperature after external pipping. Measuring T af is sufficient and adequate for experiments concerning thermoregulatory heat production in normal or lowered incubation temperatures.

Validation of subcutaneous temperature as a measure of deep body temperature in small bats

Validation of subcutaneous temperature as a measure of deep body temperature in small bats

The application of intrascrotal deep body temperature measurement for the noninvasive diagnosis of varicoceles

The authors used intrascrotal deep body (intratesticular) temperature measurement in an attempt to make the diagnosis of varicoceles more objective. Two hundred five male patients complaining of infertility were classified into three groups: group A consisted of 84 patients with varicocele; group B of 66 patients without varicocele; and group C of 55 patients after varicocelectomy. The bilateral intrascrotal temperatures were recorded in the supine position and then monitored continuously in the standing position. The maximum temperatures in both positions were compared between each group. The mean temperature of the varicocele group was higher than that of the other two groups in the standing position. The authors studied the difference in temperature (delta T) due to postural change from supine to standing. The mean delta T of the left testis was +0.78 degrees C in the varicocele group, whereas it was approximately -0.5 degrees C in the other two groups. The authors conclude that deep body temperature provides a practical index of the intrascrotal temperature and is useful as one of the objective, clinical criteria for the diagnosis of varicocele.

Mammalian hibernation and the oxygen consumption of a denning black bear ( Ursus americanas)

1. 1. Definitive criteria for mammalian hibernation are reviewed and a new definition based upon specialized metabolic reductions is developed. 2. 2. Results of indirect calorimetry, heart rates and deep body temperature measurements on a denning black bear are discussed with respect to the proposed definition.

A modular expandable implantable temperature biotelemeter.

An implantable biotelemetry system is described for multisite temperature measurements with ease of expansion by use of different master circuit boards to accommodate additional channels. Modular construction of the multichannel FM-FM system allows addition or deletion of channels as the experiment requires. The radio frequency carrer osciUlator is tunable to a "quiet" frequency in the 90-105 MHz range prior to implantation. The telemeter may incorporate enclosed or remote temperature probes which allow deep body temperature measurements in the range of 30-42 °C with an available resolution of ±0.015°C. Transmitters have been utilized in monitoring ovarian and subcutaneous temperatures, and also as an aid in detection of ovulation in the Macaca mulatta.

Analysis of ovulation-oviposition patterns in the domestic fowl by telemetry measurement of deep body temperature.

Continuous temperature records in relation to time of oviposition and behaviour associated with it are summarized for 13 laying strain pullets with a regular pattern of oviposition and for a further 10 pullets which were either 'internal layers' , or natural or induced layers of membranous-shell eggs. The records of five pullets, in which the most recently ruptured follicle was excised within 2-5 h after ovulation, and of four control pullets are also included.

Measurement of deep body temperature from the urine.

1. The relation between urine and rectal temperatures has been studied under a variety of conditions by using the Uritemp bottle, which measures deep body temperature from the urine. 2. This device gives a reliable measurement of deep body temperature and has advantages over both rectal and oral techniques for many clinical applications. 3. The development of a new and more reliable device, the Uritemp meter, is described. Urine is voided through a specially designed and disposable unit, equipped with either a standard mercury-in-glass thermometer or any one of a range of commercially available electronic thermometers. Provision is made to collect a urine sample simultaneously if required.

Comparison of rectal and deep body temperature in the calf.

IN the bovine animal as with other domestic mammals including man, the rectal temperature is generally accepted as a measure of deep body temperature, and it is widely used both in field and laboratory studies for indicating the state of thermal balance of cattle when subjected to climatic stress. Despite the possibility of thermal gradients within the rectum, as has been found in man1, there is no obvious reason for doubting the validity of this assumption, at least as an approximation, when body temperatures are steady. However, under conditions of thermal stress, when body temperatures are rising, a constant and close relationship between rectal and deep-body temperature cannot be assumed, as there is almost certainly a delay before the temperature of the faecal mass reaches equilibrium with that of the rectal wall. Consequently, an investigation has been made ta study the validity of using rectal temperature as a measure of deep body temperature in Ayrshire bull calves, four to six months old. Cattle of this age and breed have already been used in studies of environmental physiology in a climatic chamber in this Institute2.