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A new noninvasive core-thermometry technique, based on the use of two heat flux sensors with different very low thermal resistances, is proposed. Thermodynamically derived equations, using a pair of skin temperatures and heat fluxes detected from the sensors, can give the estimated deep body temperature (DBT) together with thermal resistance of the skin tissue itself. The validity and accuracy of this method are firstly investigated through in vitro experiments using a tissue phantom model and, secondly, as in vivo comparisons with sublingual (Tsub) or rectal temperature (Trec) measurements in 9 volunteers, attaching the sensors around the upper sternum or the nape. Model experiments showed a good agreement between the measured and estimated temperatures, ranging from approximately 36 to 42 ℃. In vivo experiments demonstrated linear correlations between the estimated DBT and both Tsub and Trec values, though the estimated DBT was 0.13 ℃ higher than Tsub and 0.42 ℃ lower than Trec on average. The results also strongly suggested the possibility to estimate the tissue thermal resistance; this is discussed herein. Although further in vivo experiments under various environmental conditions are necessary, this method appears highly promising as an accurate, useful and convenient core-thermometry system for medical and healthcare settings. Overview drawing of a new deep body thermometry technique from the skin surface using two heat flux sensors with different very low thermal resistances shown in the upper left part. In vivo experiments demonstrated a good agreement between the measured (sublingual and rectal) and estimated temperatures shown in right upper part. The results also strongly suggested the possibility to estimate the skin tissue thermal resistance and this is described in detail in this paper. The present method is highly promising as an accurate, useful and convenient core-thermometry system for medical and healthcare settings and could be used in daily life through further development as shown in the lower right part. [ABSTRACT FROM AUTHOR]

Heatstroke is a concern during sudden heat waves. We designed and prototyped an Internet of Things system for heatstroke prevention, which integrates physiological information, including deep body temperature (DBT), based on the dual-heat-flux method. A dual-heat-flux thermometer developed to monitor DBT in real-time was also evaluated. Real-time readings from the thermometer are stored on a cloud platform and processed by a decision rule, which can alert the user to heatstroke. Although the validation of the system is ongoing, its feasibility is demonstrated in a preliminary experiment. [ABSTRACT FROM AUTHOR]

Aim The study aimed to determine the current status of face mask use, deep body temperature measurement, and active cooling in patients suffering from heat stroke and heat exhaustion in Japan. Methods 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. Results 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. Heat strokes had significantly higher rates of active cooling and lower mortality rates than heat stroke‐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. Conclusions 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.

Purpose: "Ice-mile" swimming presents significant physiological challenges and potential safety issues, but few data are available. This study examined deep body temperature (BT), respiratory rate (RR), and swim performance in 2 swimmers completing an ice-mile swim of 1 mile (1600 m) in water less than 5°C. Methods: Two male cold-water-habituated swimmers completed a 1-mile lake swim in 3.9°C water. For comparative purposes, they completed an indoor 1-mile swim in 28.1°C water. The Equivital physiological monitoring system was used to record BT and RR before, during, and after each swim. Total time to complete the swims and 400-m splits were recorded. Results: One swimmer became hypothermic after 27 min while swimming, reaching BT of 33.7°C at swim's end. On exiting the water the swimmers experienced large BT after-drops of -3.6°C and -2.4°C, reaching low points of 33.2°C and 31.3°C 38 and 23 min postswim, respectively. Respiratory rate and swim pace decreased over the course of the ice-mile swim for both swimmers. Swim pace for 1 swimmer declined sharply in the final 400-m lap of the ice mile when he was hypothermic. Both swimmers remained hypothermic 60 min postswim (34.2°C and 33.4°C). Conclusions: Ice-mile swimmers may become hypothermic while swimming, and the postswim BT after drop may expose them to dangerous levels of hypothermia. Pace and RR should be monitored as proxies for a swimmer's physiological state. Postswim recovery should also be monitored for hypothermia for at least 1 h. [ABSTRACT FROM AUTHOR]

Heatstroke is a concern during sudden heat waves. We designed and prototyped an Internet of Things system for heatstroke prevention, which integrates physiological information, including deep body temperature (DBT), based on the dual-heat-flux method. A dual-heat-flux thermometer developed to monitor DBT in real-time was also evaluated. Real-time readings from the thermometer are stored on a cloud platform and processed by a decision rule, which can alert the user to heatstroke. Although the validation of the system is ongoing, its feasibility is demonstrated in a preliminary experiment.

There is a need to rapidly screen individuals for heat strain and fever using skin temperature (Tsk) as an index of deep body temperature (Tb). This study’s aim was to assess whether Tsk could serve as an accurate and valid index of Tb during a simulated heatwave. Seven participants maintained a continuous schedule over 9-days, in 3-day parts; pre-/post-HW (25.4 °C), simulated-HW (35.4 °C). Contact thermistors measured Tsk (Tforehead, Tfinger); radio pills measured gastrointestinal temperature (Tgi). Proximal-distal temperature gradients (ΔTforehead–finger) were also measured. Measurements were grouped into ambient conditions: 22, 25, and 35 °C. Tgi and Tforehead only displayed a significant relationship in 22 °C (r: 0.591; p < 0.001) and 25 °C (r: 0.408; p < 0.001) conditions. A linear regression of all conditions identified Tforehead and ΔTforehead–finger as significant predictors of Tgi (r2: 0.588; F: 125.771; p < 0.001), producing a root mean square error of 0.26 °C. Additional residual analysis identified Tforehead to be responsible for a plateau in Tgi prediction above 37 °C. Contact Tforehead was shown to be a statistically suitable indicator of Tgi in non-HW conditions; however, an error of ~1 °C makes this physiologically redundant. The measurement of multiple sites may improve Tb prediction, though it is still physiologically unsuitable, especially at higher ambient temperatures.

Highlights • Hypertensive rats do not exhibit bradycardic and hypothermic responses to hypercapnia. • AOA permits a drop in body temperature in hypercapnia-exposed hypertensive rats. • AOA does not alter the cardiovascular response to hypercapnia in hypertensive rats. • Hypercapnic ventilatory response is not changed by AOA in hypertensive rats. Abstract Hydrogen sulfide (H 2 S) is classically known for its toxic effects. More recently H 2 S has been documented as a neuromodulator. Here we investigated the central effects of aminooxyacetate (AOA; inhibitor of the H 2 S-synthesizing enzyme cystathionine β-synthase, CBS) on cardiovascular, respiratory and thermoregulatory responses to hypercapnia in spontaneously hypertensive rats (SHR). To attain this goal we measured mean arterial pressure (MAP), heart rate (HR), ventilation (V E), and deep body temperature (Tb) of SHR and (normotensive) Wistar Kyoto (WKY) rats before and after microinjection of AOA (9 nmol/μL) or saline into the fourth ventricle immediately followed by 30-min hypercapnia exposure (7% inspired CO 2). In saline-treated WKY rats, hypercapnia caused an increase in MAP accompanied by bradycardia, an increase in V E , and a drop in Tb. In AOA-treated WKY rats exposed to hypercapnia, the drug did not affect the increased MAP, potentiated the bradycardic response, attenuated the increased V E , and potentiated the drop in Tb. In saline-treated SHR, in comparison to the saline-treated WKY rats, hypercapnia elicited a minor, shorter-lasting increase in MAP with no changes in HR, evoked a greater increase in V E , and did not induce a drop in Tb. In AOA-treated SHR exposed to hypercapnia, the drug did not change the hypercapnia-induced cardiovascular and ventilatory responses while permitted a drop in Tb. Our findings indicate that AOA, an inhibitor of H 2 S production, modulates cardiorespiratory and thermoregulatory responses to hypercapnia in normotensive rats, whereas hypertension development in SHR is accompanied by suppression of the AOA effect on the cardiovascular and respiratory responses. [ABSTRACT FROM AUTHOR]

Objectives The aim was to ascertain hydration and heat strain of construction workers in Japan during the summer who are at the highest risk of heat-related disorders. Methods The subjects were 23 construction workers, whose average age was 41, average weight was 69 kg, and average height was 170 cm. We measured thermal working conditions with a wet bulb globe temperature (WBGT) measurement instrument affixed to the helmet of each worker, at fixed points outdoors in the sun and indoors. Heat strain was evaluated for water intake, urine specific gravity (Usg), urine temperature (UT), heart rate (HR), and body weight during work. Results The average WBGT measured on the worker helmets over 3 consecutive days was 28.0 ± 0.7, 27.6 ± 0.8, and 27.6 ± 1.1°C. The average water intake was 2.6 l during a work shift. The average Usg, UT, and % HR reserve were the highest in the first half of afternoon work. Seventy-eight percent of the subjects exceeded at least one of the ACGIH TLV physiological guidelines for heat strain in terms of HR and weight loss or a clinically dehydrated level of Usg. Conclusions Heat strain was the highest in the first half of afternoon work. The number of dehydrated workers increased during this shift because of insufficient water intake. Adequate hydration is required to decrease the risk of heat-related disorders among construction workers in the summer. [ABSTRACT FROM AUTHOR]

Background: Cardiovascular (CV) and thermal responses to metabolically demanding multi-day military operations in extreme cold-weather environments are not well described. Characterization of these operations will provide greater insights into possible performance capabilities and cold injury risk. Methods: Soldiers from two cold-weather field training exercises (FTX) were studied during 3-day (study 1, n = 18, age: 20 ± 1 year, height: 182 ± 7 cm, mass: 82 ± 9 kg) and 4-day (study 2, n = 10, age: 20 ± 1 year, height: 182 ± 6 cm, mass: 80.7 ± 8.3 kg) ski marches in the Arctic. Ambient temperature ranged from −18 to −4 °C during both studies. Total daily energy expenditure (TDEE, from doubly labeled water), heart rate (HR), deep body ( T ), and torso ( T ) skin temperature (obtained in studies 1 and 2) as well as finger ( T ), toe ( T ), wrist, and calf temperatures (study 2) were measured. Results: TDEE was 6821 ± 578 kcal day and 6394 ± 544 for study 1 and study 2, respectively. Mean HR ranged from 120 to 140 bpm and mean T ranged between 37.5 and 38.0 °C during skiing in both studies. At rest, mean T ranged from 36.0 to 36.5 °C, (lowest value recorded was 35.5 °C). Mean T ranged from 32 to 35 °C during exercise and dropped to 15 °C during rest, with some T values as low as 6-10 °C. T was above 30 °C during skiing but dropped to 15-20 °C during rest. Conclusions: Daily energy expenditures were among the highest observed for a military training exercise, with moderate exercise intensity levels (~65% age-predicted maximal HR) observed. The short-term cold-weather training did not elicit high CV and T strain. T and T were also well maintained while skiing, but decreased to values associated with thermal discomfort at rest. [ABSTRACT FROM AUTHOR]

Traditional environmental control methods for poultry housing which rely solely on environmental factors fall short in meeting thermal and physiological needs of the animals. New methods are needed that factor in the physiological needs and responses of the animals in order to maximize well-being of the animals and minimize heat stress. Deep body temperature (DBT) has been shown in the literature to be a strong indicator of heat stress, therefore studies are needed that help us gain a deeper understanding of the relationship between this variable and environmental conditions. The aim of this study was to identify the order of the dynamic response of poultry DBT to large step changes in ambient temperature (AT). Temperature steps had to be big enough to take the chickens out of their homeothermic zone. A total of 46 DBT/AT data sets with 23 upward AT steps and 23 downward AT steps were obtained using a biotelemetry system, and involving three chickens. DBT responses of individual chickens to step changes in AT were found to have a 0.88 average Pearson correlation suggesting consistency in chickens' responses to the same stimuli (p<0.0005). The data indicated that DBT responses to AT followed a first order behavior in most cases with an average time constant of 1.6 h, and the curve fitting method was used to validate this observation. There was a 0.88 average correlation between DBT model and measured data (p<0.0005). These results indicate statistical significance in the data used and the model derived from it. In conclusion, it is reasonable to assume that the dynamic response of poultry DBT to large step changes in ambient temperature follows a first order model. Although further studies are needed to more fully derive the model, this study provided a stepping-stone towards gaining a better understanding of the relationship between DBT and AT, therefore taking us one step closer towards making optimal management and risk assessment decisions that are based on physiological needs of the chickens. [ABSTRACT FROM AUTHOR]

Tunnel ventilation has been adopted as an effective approach to combatting heat stress in poultry. Setting tunnel air velocity to levels that ensure bird comfort, while optimizing performance is an important goal. In recent years, biotelemetry has provided a way to effectively evaluate the impact of management practices on poultry physiology. In this study, we present an approach for evaluating the effects of heat stress and tunnel ventilation on poultry deep body temperature (DBT) using biotelemetry. Three consecutive experiments were conducted using 6 broilers, each at the ages of 8.6, 9.0, and 9.4 wk. Experiments spanned approximately 12 h each and led to 18 data sets. DBT responses of birds under no ventilation rose by as much as 3°C as a result of step increases in ambient temperature. Birds exposed to tunnel ventilation maintained a lower DBT by as much as 0.9°C. During experiment days, birds exposed to tunnel ventilation consistently gained weight with a percentage weight gain ranging from 1% to 11%. Birds not exposed to tunnel ventilation behaved less consistently with some gaining as much as 14% while others lost as much as 9%. Although further studies are required to derive more comprehensive and more statistically significant results, this study provided preliminary data that is needed to warrant such studies, and a stepping stone for making optimal management and risk assessment decisions that are based on physiological needs of the birds. [ABSTRACT FROM AUTHOR]

Aim: The study aimed to determine the current status of face mask use, deep body temperature measurement, and active cooling in patients suffering from heat stroke and heat exhaustion in Japan., Methods: 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., Results: 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. Heat strokes had significantly higher rates of active cooling and lower mortality rates than heat stroke-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., Conclusions: 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., (© 2023 The Authors. Acute Medicine & Surgery published by John Wiley & Sons Australia, Ltd on behalf of Japanese Association for Acute Medicine.)

The aims of the present work were to investigate the relationships between radiant heat load, air velocity and body temperatures with or without coincidental exercise to determine the physiological mechanisms that drive thermal comfort and thermoregulatory behaviour. Seven male volunteers wearing swimming trunks in 18 °C, 22 °C or 26 °C air were exposed to increasing air velocities up to 3 m s − 1 and self-adjusted the intensity of the direct radiant heat received on the front of the body to just maintain overall thermal comfort, at rest or when cycling (60 W, 60 rpm). During the 30 min of the experiments, skin and rectal temperatures were continuously recorded. We hypothesized that mean body temperature should be maintained stable and the intensity of the radiant heat and the mean skin temperatures would be lower when cycling. In all conditions, mean body temperature was lower when facing winds of 3 m s −1 than during the first 5 min, without wind. When facing winds, in all but the 26 °C air, the radiant heat was statistically higher at rest than when exercising. In 26 °C air mean skin temperature was lower at rest than when exercising. No other significant difference was observed. In all air temperatures, high correlation coefficients were observed between the air velocity and the radiant heat load. Other factors that we did not measure may have contributed to the constant overall thermal comfort status despite dropping mean skin and body temperatures. It is suggested that the allowance to behaviourally adjust the thermal environment increases the tolerance of cold discomfort. [ABSTRACT FROM AUTHOR]

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 themuscle 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 ?Csystematic 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. [ABSTRACT FROM AUTHOR]

There is a need to rapidly screen individuals for heat strain and fever using skin temperature (Tsk) as an index of deep body temperature (Tb). This study's aim was to assess whether Tsk could serve as an accurate and valid index of Tb during a simulated heatwave. Seven participants maintained a continuous schedule over 9-days, in 3-day parts; pre-/post-HW (25.4 °C), simulated-HW (35.4 °C). Contact thermistors measured Tsk (Tforehead, Tfinger); radio pills measured gastrointestinal temperature (Tgi). Proximal-distal temperature gradients (ΔTforehead–finger) were also measured. Measurements were grouped into ambient conditions: 22, 25, and 35 °C. Tgi and Tforehead only displayed a significant relationship in 22 °C (r: 0.591; p < 0.001) and 25 °C (r: 0.408; p < 0.001) conditions. A linear regression of all conditions identified Tforehead and ΔTforehead–finger as significant predictors of Tgi (r2: 0.588; F: 125.771; p < 0.001), producing a root mean square error of 0.26 °C. Additional residual analysis identified Tforehead to be responsible for a plateau in Tgi prediction above 37 °C. Contact Tforehead was shown to be a statistically suitable indicator of Tgi in non-HW conditions; however, an error of ~1 °C makes this physiologically redundant. The measurement of multiple sites may improve Tb prediction, though it is still physiologically unsuitable, especially at higher ambient temperatures. [ABSTRACT FROM AUTHOR]

Current poultry housing environmental controllers do not directly factor in the state of the birds themselves, such as their deep body temperature (DBT) responses. In this article, we propose and investigate the feasibility of a new approach for real-time closed-loop control of poultry DBT under heat stress condition's using variable air velocity. Using five commercial breed broilers, an experimental tunnel ventilation enclosure placed inside an environmentally controlled chamber, implanted radio telemetry sensors, and a programmable logic controller (PLC), four experimental trials were conducted using a proportional-integral type feedback controller. The results indicated that (1) air velocity has a measurable, dynamic, and almost immediate impact on DBT of birds under heat stress; and (2) DBT of heat-stressed broilers can be maintained below a setpoint by varying air velocity using feedback control These preliminary results suggest that using DBT as a feedback variable to manipulate air velocity within poultry housing is a promising approach. This article represents a first step towards the design of the future poultry environmental controller that responds directly to the physiological needs of the birds. [ABSTRACT FROM AUTHOR]

Of 103 patients who underwent varicocelectomies, 87 underwent all the diagnostic methods: color Doppler ultrasonography (DOP), scrotal deep body temperature (DBT), and scrotal scintigraphy (SSG). Total motile sperm (TM) was calculated. The positivities of DOP, DBT, and SSG were 67, 51, and 90%, respectively. In the patients <30 years old, TM increased in the DBT-positive group. In older patients, positive for DBT indicated poor improvement of TM, whereas positive for DOP indicated better response in the group. Patients older than 30 years and positive for DBT, but not DOP, should be counseled directly to receive intrauterine insemination or in vitro fertilization/intracytoplasmic sperm injection. [ABSTRACT FROM AUTHOR]

Aim: To investigate whether infants with intrauterine growth retardation (IUGR) experience different changes in temperature and cortisol excretion after routine immunization compared with normal healthy infants.Methods: Overnight deep body temperature and urinary cortisol to creatinine ratios were measured on the night after immunization and a control night in normal and IUGR infants.Results: In 60 normal infants, first vaccination at about 10 wk of age led to a significant increase in minumum overnight temperature compared to the control night, mean rise 0.25 degrees C (95% CI, 0.12 to 0.38). In 35 IUGR infants the mean rise in temperature between immunization night and control night was 0.35 degrees C (95% CI, 0.15 to 0.55). The increases in minimum temperature did not differ significantly between the normal and IUGR infants (p = 0.11). Cortisol to creatinine ratios measured from overnight urine samples showed that 23 IUGR infants had consistently higher levels than 39 normal infants: control night medians 34 and 15 (p=0.01) and immunization night medians 56 and 26 (p = 0.02), respectively. However, the percentage increase did not differ significantly between the IUGR infants and the normal infants. A smaller number of second immunizations were studied, but no significant differences were found.Conclusion: These results suggest that although the impact of immunization is the same for IUGR and normal infants, because IUGR infants are less mature and at greater stress before immunization, the absolute levels that they experience after immunization are higher than those for normal infants. [ABSTRACT FROM AUTHOR]

Diary sleep and oral body temperature data are presented for two groups of experienced rotating shiftworkers (2 or 3, and 5 successive night shifts). The data analysis shows for both rotas: a flattened temperature curve on night shift; 'sleep loss' on both morning and night shift; few breaks in sleep for either day or night sleeps, with no significant increase for day sleeps; a marked tendency for no-day sleep to be taken prior to the first night shift; and a shorter latency to sleep onset for day sleep. The night shift body temperature curves and diary sleep data are related to earlier studies. They are interpreted as reflecting partial-not chronic-sleep loss, and an ongoing normal circadian rhythmicity. No particular number of consecutive night shifts is recommended. Rather it is suggested that shift rota selection should be based on an assessment of how the rota will facilitate an acceptable balance between useful free time and sleep duration for individual work groups. [ABSTRACT FROM AUTHOR]