FDTD analysis of body-core temperature elevation in children and adults for whole-body exposure

Extreme whole-body hyperthermia was achieved without lasting side effects in canines by elevating body core temperature to 42 degrees C, using a warm water bath. Cold water irrigation of the nasal alar fold permitted an additional core temperature elevation of 0.5–1.0 degrees C above brain temperature for periods up to 1.5 h. The brain-core temperature differential was maintained by a physiological arteriovenous heat exchanger located at the base of the brain. The maximum tolerable core temperature for the 21 nonirrigated dogs was 42 degrees C for 60–90 min, whereas that for the 28 irrigated dogs was 42.5–43 degrees C for similar time intervals. A mathematical model of the total heat transfer system described the observed dynamic temperature responses. It was the solution of a differential equation which fit the normalized experimental data points and predicted reasonable values for known and unknown experimental parameters.

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Restoration of thermoregulation after exercise

Journal of Applied Physiology ◽

10.1152/japplphysiol.00517.2016 ◽

2017 ◽

Vol 122 (4) ◽

pp. 933-944 ◽

Cited By ~ 32

Author(s):

Glen P. Kenny ◽

Ryan McGinn

Keyword(s):

Heat Loss ◽

Core Temperature ◽

Current Knowledge ◽

Thermal Control ◽

The Body ◽

Body Core Temperature ◽

Whole Body ◽

Temperature Sensitive ◽

Internal Core ◽

Body Core

Performing exercise, especially in hot conditions, can heat the body, causing significant increases in internal body temperature. To offset this increase, powerful and highly developed autonomic thermoregulatory responses (i.e., skin blood flow and sweating) are activated to enhance whole body heat loss; a response mediated by temperature-sensitive receptors in both the skin and the internal core regions of the body. Independent of thermal control of heat loss, nonthermal factors can have profound consequences on the body’s ability to dissipate heat during exercise. These include the activation of the body’s sensory receptors (i.e., baroreceptors, metaboreceptors, mechanoreceptors, etc.) as well as phenotypic factors such as age, sex, acclimation, fitness, and chronic diseases (e.g., diabetes). The influence of these factors extends into recovery such that marked impairments in thermoregulatory function occur, leading to prolonged and sustained elevations in body core temperature. Irrespective of the level of hyperthermia, there is a time-dependent suppression of the body’s physiological ability to dissipate heat. This delay in the restoration of postexercise thermoregulation has been associated with disturbances in cardiovascular function which manifest most commonly as postexercise hypotension. This review examines the current knowledge regarding the restoration of thermoregulation postexercise. In addition, the factors that are thought to accelerate or delay the return of body core temperature to resting levels are highlighted with a particular emphasis on strategies to manage heat stress in athletic and/or occupational settings.

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Modeling of Differences Between Body Core and Forehead Temperatures Measured by Infrared Thermometers

2017 Design of Medical Devices Conference ◽

10.1115/dmd2017-3439 ◽

2017 ◽

Author(s):

Oleg Vesnovsky ◽

Yiyong Li ◽

L. D. Timmie Topoleski ◽

Liang Zhu

Keyword(s):

Heat Transfer ◽

Core Temperature ◽

Ebola Virus ◽

Thermal Environment ◽

Surface Condition ◽

The United States ◽

The Body ◽

Body Core Temperature ◽

Whole Body ◽

Body Core

In recent years, outbreaks of highly contagious diseases, like the Ebola virus, have motivated vigorous efforts to screen travelers entering the United States, especially at airports. Screening involves monitoring the body temperature of entering travelers, and blocking entry of those showing a fever, indicating a potential infection. Typically, screening is performed using commercially available non-contact infrared thermometers (NCITs). These thermometers require specific use protocols (e.g., working distances) to provide accurate results, which may not be followed by inspectors reluctant to approach potentially contagious travelers. Furthermore, the NCITs’ accuracy is based on an assumption that the NCIT readings from a forehead will predict the body core temperatures using a simple common one-size-fits-all correction offset. Unfortunately, the temperature detected on the forehead surface by an NCIT may not represent the true body core temperature, due to the changing conditions of the external environment and/or surface conditions of the forehead skin. It is not clear whether the correction factor is able to adjust to the thermal environment, or whether the surface condition of the forehead, including sweat and skin tone, affects the NCIT readings. Before a clinical study is conducted to understand the differences between the forehead temperatures and the body core temperatures, a computational model to simulate temperature distribution inside and on the surface of the body is a cost-effective way to identify factors that influence the temperatures and to study the reasons for their deviations. The objectives of this study were to 1) develop a numerical whole-body model and perform computational heat transfer simulations of different body geometries and 2) perform parametric studies to evaluate the effect of environmental factors, such as air temperature and heat transfer coefficient, on the differences between the forehead temperature and body core temperature. This data can be used to evaluate correction factors or needed to use the measured forehead temperature to predict the body core temperature.

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FDTD analysis of human body-core temperature elevation due to RF far-field energy prescribed in the ICNIRP guidelines

Physics in Medicine and Biology ◽

10.1088/0031-9155/52/16/020 ◽

2007 ◽

Vol 52 (16) ◽

pp. 5013-5023 ◽

Cited By ~ 36

Author(s):

Akimasa Hirata ◽

Takayuki Asano ◽

Osamu Fujiwara

Keyword(s):

Core Temperature ◽

Human Body ◽

Body Core Temperature ◽

Field Energy ◽

Far Field ◽

Temperature Elevation ◽

Body Core

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Faculty Opinions recommendation of Circadian disruption of body core temperature and rest-activity rhythms after general (propofol) anesthesia in rats.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1162503.624034 ◽

2009 ◽

Author(s):

Misha Perouansky

Keyword(s):

Core Temperature ◽

Circadian Disruption ◽

Body Core Temperature ◽

Activity Rhythms ◽

Body Core ◽

Rest Activity

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The recommended Threshold Limit Values for heat exposure fail to maintain body core temperature within safe limits in older working adults

Journal of Occupational and Environmental Hygiene ◽

10.1080/15459624.2017.1321844 ◽

2017 ◽

Vol 14 (9) ◽

pp. 703-711 ◽

Cited By ~ 13

Author(s):

Dallon T. Lamarche ◽

Robert D. Meade ◽

Andrew W. D'Souza ◽

Andreas D. Flouris ◽

Stephen G. Hardcastle ◽

...

Keyword(s):

Core Temperature ◽

Heat Exposure ◽

Body Core Temperature ◽

Limit Values ◽

Threshold Limit Values ◽

Working Adults ◽

Threshold Limit ◽

Body Core ◽

Safe Limits

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Hypothalamic paraventricular nucleus is critical for renal vasoconstriction elicited by elevations in body temperature

AJP Renal Physiology ◽

10.1152/ajprenal.00488.2007 ◽

2008 ◽

Vol 294 (2) ◽

pp. F309-F315 ◽

Cited By ~ 12

Author(s):

Joo Lee Cham ◽

Emilio Badoer

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Blood Flow ◽

Renal Blood Flow ◽

Core Temperature ◽

Paraventricular Nucleus ◽

Hypothalamic Paraventricular Nucleus ◽

Body Core Temperature ◽

Control Group ◽

Body Core

Redistribution of blood from the viscera to the peripheral vasculature is the major cardiovascular response designed to restore thermoregulatory homeostasis after an elevation in body core temperature. In this study, we investigated the role of the hypothalamic paraventricular nucleus (PVN) in the reflex decrease in renal blood flow that is induced by hyperthermia, as this brain region is known to play a key role in renal function and may contribute to the central pathways underlying thermoregulatory responses. In anesthetized rats, blood pressure, heart rate, renal blood flow, and tail skin temperature were recorded in response to elevating body core temperature. In the control group, saline was microinjected bilaterally into the PVN; in the second group, muscimol (1 nmol in 100 nl per side) was microinjected to inhibit neuronal activity in the PVN; and in a third group, muscimol was microinjected outside the PVN. Compared with control, microinjection of muscimol into the PVN did not significantly affect the blood pressure or heart rate responses. However, the normal reflex reduction in renal blood flow observed in response to hyperthermia in the control group (∼70% from a resting level of 11.5 ml/min) was abolished by the microinjection of muscimol into the PVN (maximum reduction of 8% from a resting of 9.1 ml/min). This effect was specific to the PVN since microinjection of muscimol outside the PVN did not prevent the normal renal blood flow response. The data suggest that the PVN plays an essential role in the reflex decrease in renal blood flow elicited by hyperthermia.

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MK801 impairs thermoregulation in the heat

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y02-055 ◽

2002 ◽

Vol 80 (3) ◽

pp. 226-232 ◽

Cited By ~ 5

Author(s):

Frédéric Canini ◽

Nadine Simler ◽

Lionel Bourdon

Keyword(s):

Locomotor Activity ◽

Nmda Receptor ◽

Receptor Antagonist ◽

Core Temperature ◽

Exposure Duration ◽

Heat Exposure ◽

Nmda Receptor Antagonist ◽

Dopamine Metabolism ◽

Body Core Temperature ◽

Body Core

The effects of MK801 (dizocilpine), a glutamate NMDA receptor antagonist, on thermoregulation in the heat were studied in awake rats exposed to 40°C ambient temperature until their body core temperature reached 43°C. Under these conditions, MK801-treated rats exhibited enhanced locomotor activity and a steady rise in body core temperature, which reduced the heat exposure duration required to reach 43°C. Since MK801-treated rats also showed increased striatal dopaminergic metabolism at thermoneutrality, the role of dopamine in the MK801-induced impairment of thermoregulation in the heat was determined using co-treatment with SCH23390, a dopamine D1 receptor antagonist. SCH23390 normalized the locomotor activity in the heat without any effect on the heat exposure duration. These results suggest that the MK801-induced impairment of thermoregulation in the heat is related to neither a dopamine metabolism alteration nor a locomotor activity enhancement.Key words: heatstroke, NMDA receptor, thermoregulation, dopamine, locomotion.

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