Comparison Between Experimental and Heart Rate-Derived Core Body Temperatures Using a Three-Dimensional Whole Body Model

2018 ◽  
Vol 11 (2) ◽  
Author(s):  
Rupak K. Banerjee ◽  
Robins T. Kalathil ◽  
Swarup A. Zachariah ◽  
Anup K. Paul ◽  
Amit Bhattacharya ◽  
...  
Keyword(s):  
Heart Rate ◽  
Real Time ◽  
Core Body Temperature ◽  
Three Dimensional ◽  
Thermal Response ◽  
Whole Body ◽  
Body Model ◽  
Thermoregulatory Model ◽  
Core Body ◽  
Whole Body Model

Abstract Determination of core body temperature (Tc), a measure of metabolic rate, in firefighters is needed to avoid heat-stress related injury in real time. The measurement of Tc is neither routine nor trivial. This research is significant as thermal model to determine Tc is still fraught with uncertainties and reliable experimental data for validation are rare. The objective of this study is to develop a human thermoregulatory model that uses the heart rate measurements to obtain Tc for firefighters using a 3D whole body model. The hypothesis is that the heart rate-derived computed Tc correlates with the measured Tc during firefighting activities. The transient thermal response of the human body was calculated by simultaneously solving the Pennes' bioheat and energy balance equations. The difference between experimental and numerical values of Tc was less than 2.6%. More importantly, a ± 10% alteration in heart rate was observed to have appreciable influence on Tc, resulting in a ± 1.2 °C change. A 10% increase in the heart rate causes a significant relative % increase (52%) in Tc, considering its allowable/safe limit of 39.5 °C. Routine acquisition of the heart rate data during firefighting scenario can be used to derive Tc of firefighters in real time using the proposed 3D whole body model.

Influence of Exercise Condition on Tissue Blood Temperature Using Whole Body Model

2013 ◽  
Author(s):  
Swarup A. Zachariah ◽  
Anup K. Paul ◽  
Rupak K. Banerjee ◽  
Liang Zhu
Keyword(s):  
Human Body ◽  
Core Body Temperature ◽  
Thermal Response ◽  
The Body ◽  
Tissue Temperature ◽  
Whole Body ◽  
Transfer Model ◽  
Blood Temperature ◽  
Exercise Condition ◽  
Core Body

Predicting thermal responses of the human body accurately during different exercise conditions is of increasing importance. Computing changes in the core body temperature (T c) during exercise require detailed modeling of both the body tissue temperature and the time-dependent blood temperature. Predicting changes in T c is challenging because the model needs to respond effectively to the changes in perfusion or sweating. Our study was to demonstrate the ability of a recently developed whole body heat transfer model. It simulates the tissue-blood interaction to predict the thermal response of the human body under different exercise intensities. The cases simulated were of a human being walking on a treadmill at 0.9, 1.2 and 1.8 m/s for 30 minutes. It was shown that T c was effectively regulated within 0.17 °C of the steady state value of 37.23 °C for the three cases by means of adjusting the cardiac output; varying between 15 to 25 liters per minute.

scholarly journals Influence of external head cooling on the head, core body and blood temperatures using 3D whole-body model

2018 ◽  
Vol 28 (10) ◽  
pp. 2491-2504
Author(s):  
Surendra Balaji Devarakonda ◽  
Pallavi Bulusu ◽  
Marwan Al-rjoub ◽  
Amit Bhattacharya ◽  
Rupak Kumar Banerjee
Keyword(s):  
Human Body ◽  
Computational Study ◽  
Whole Body ◽  
Content Type ◽  
Body Model ◽  
Head Cooling ◽  
Experimental Values ◽  
Core Body ◽  
The Impact ◽  
Whole Body Model

Purpose The purpose of this study is to evaluate the impact of external head cooling on alleviating the heat stress in the human body by analyzing the temperatures of the core body (Tc), blood (Tblood) and head (Th) during exercise conditions using 3D whole body model. Design/methodology/approach Computational study is conducted to comprehend the influence of external head cooling on Tc, Tblood and Th. The Pennes bioheat and energy balance equations formulated for the whole-body model are solved concurrently to obtain Tc, Tblood and Th for external head cooling values from 33 to 233 W/m2. Increased external head cooling of 404 W/m2 is used to compare the numerical and experimental Th data. Findings Significant reductions of 0.21°C and 0.38°C are observed in Th with external head cooling of 233 and 404 W/m2, respectively. However, for external head cooling of 233 W/m2, lesser reductions of 0.03°C and 0.06°C are found in Tc and Tblood, respectively. Computational results for external head cooling of 404 W/m2 show a difference of 15 per cent in Th compared to experimental values from literature. Originality/value The development of stress because of heat generated within human body is major concern for athletes exercising at high intensities. This study provides an insight into the effectiveness of external head cooling in regulating the head and body temperatures during exercise conditions.

scholarly journals Uncertainty Analysis of the Core Body Temperature Under Thermal and Physical Stress Using a Three-Dimensional Whole Body Model

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Robins T. Kalathil ◽  
Gavin A. D'Souza ◽  
Amit Bhattacharya ◽  
Rupak K. Banerjee
Keyword(s):  
Thermal Conductivity ◽  
Heat Stress ◽  
Body Temperature ◽  
Metabolic Rate ◽  
Core Body Temperature ◽  
Thermal Response ◽  
Whole Body ◽  
Tissue Properties ◽  
The Core ◽  
Core Body

Heat stress experienced by firefighters is a common consequence of extreme firefighting activity. In order to avoid the adverse health conditions due to uncompensable heat stress, the prediction and monitoring of the thermal response of firefighters is critical. Tissue properties, among other parameters, are known to vary between individuals and influence the prediction of thermal response. Further, measurement of tissue properties of each firefighter is not practical. Therefore, in this study, we developed a whole body computational model to evaluate the effect of variability (uncertainty) in tissue parameters on the thermal response of a firefighter during firefighting. Modifications were made to an existing human whole body computational model, developed in our lab, for conducting transient thermal analysis for a firefighting scenario. In conjunction with nominal (baseline) tissue parameters obtained from literature, and physiologic conditions from a firefighting drill, the Pennes' bioheat and energy balance equations were solved to obtain the core body temperature of a firefighter. Subsequently, the uncertainty in core body temperature due to variability in the tissue parameters (input parameters), metabolic rate, specific heat, density, and thermal conductivity was computed using the sensitivity coefficient method. On comparing the individual effect of tissue parameters on the uncertainty in core body temperature, the metabolic rate had the highest contribution (within ±0.20 °C) followed by specific heat (within ±0.10 °C), density (within ±0.07 °C), and finally thermal conductivity (within ±0.01 °C). A maximum overall uncertainty of ±0.23 °C in the core body temperature was observed due to the combined uncertainty in the tissue parameters. Thus, the model results can be used to effectively predict a realistic range of thermal response of the firefighters during firefighting or similar activities.

scholarly journals Estimation of cardiovascular drift through ear temperature during prolonged steady-state cycling: a study protocol

2021 ◽  
Vol 7 (1) ◽  
pp. e000907
Author(s):  
Giovanni Polsinelli ◽  
Angelo Rodio ◽  
Bruno Federico
Keyword(s):  
Heart Rate ◽  
Steady State ◽  
Body Temperature ◽  
Study Protocol ◽  
External Auditory Canal ◽  
Exercise Intensity ◽  
Core Body Temperature ◽  
Cardiovascular Drift ◽  
Core Body ◽  
Steady State Cycling

IntroductionThe measurement of heart rate is commonly used to estimate exercise intensity. However, during endurance performance, the relationship between heart rate and oxygen consumption may be compromised by cardiovascular drift. This physiological phenomenon mainly consists of a time-dependent increase in heart rate and decrease in systolic volume and may lead to overestimate absolute exercise intensity in prediction models based on heart rate. Previous research has established that cardiovascular drift is correlated to the increase in core body temperature during prolonged exercise. Therefore, monitoring body temperature during exercise may allow to quantify the increase in heart rate attributable to cardiovascular drift and to improve the estimate of absolute exercise intensity. Monitoring core body temperature during exercise may be invasive or inappropriate, but the external auditory canal is an easily accessible alternative site for temperature measurement.Methods and analysisThis study aims to assess the degree of correlation between trends in heart rate and in ear temperature during 120 min of steady-state cycling with intensity of 59% of heart rate reserve in a thermally neutral indoor environment. Ear temperature will be monitored both at the external auditory canal level with a contact probe and at the tympanic level with a professional infrared thermometer.Ethics and disseminationThe study protocol was approved by an independent ethics committee. The results will be submitted for publication in academic journals and disseminated to stakeholders through summary documents and information meetings.

“On-” and “off-” cells in the rostral ventromedial medulla of rats held in thermoneutral conditions: are they involved in thermoregulation?

2014 ◽  
Vol 112 (9) ◽  
pp. 2199-2217 ◽  
Author(s):  
Nabil El Bitar ◽  
Bernard Pollin ◽  
Daniel Le Bars
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Body Temperature ◽  
Core Body Temperature ◽  
Rostral Ventromedial Medulla ◽  
Sequence Of Events ◽  
Ventromedial Medulla ◽  
Cyclic Variations ◽  
On And Off Cells ◽  
Core Body

In thermal neutral condition, rats display cyclic variations of the vasomotion of the tail and paws, synchronized with fluctuations of blood pressure, heart rate, and core body temperature. “On-” and “off-” cells located in the rostral ventromedial medulla, a cerebral structure implicated in somatic sympathetic drive, 1) exhibit similar spontaneous cyclic activities in antiphase and 2) are activated and inhibited by thermal nociceptive stimuli, respectively. We aimed at evaluating the implication of such neurons in autonomic regulation by establishing correlations between their firing and blood pressure, heart rate, and skin and core body temperature variations. When, during a cycle, a relative high core body temperature was reached, the on-cells were activated and within half a minute, the off-cells and blood pressure were depressed, followed by heart rate depression within a further minute; vasodilatation of the tail followed invariably within ∼3 min, often completed with vasodilatation of hind paws. The outcome was an increased heat loss that lessened the core body temperature. When the decrease of core body temperature achieved a few tenths of degrees, sympathetic activation switches off and converse variations occurred, providing cycles of three to seven periods/h. On- and off-cell activities were correlated with inhibition and activation of the sympathetic system, respectively. The temporal sequence of events was as follows: core body temperature → on-cell → off-cell ∼ blood pressure → heart rate → skin temperature → core body temperature. The function of on- and off-cells in nociception should be reexamined, taking into account their correlation with autonomic regulations.

scholarly journals Cardiovascular changes during daily torpor in the laboratory mouse

2009 ◽  
Vol 297 (3) ◽  
pp. R769-R774 ◽  
Author(s):  
Steven J. Swoap ◽  
Margaret J. Gutilla
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Core Body Temperature ◽  
Laboratory Mouse ◽  
Caloric Intake ◽  
Peripheral Resistance ◽  
Cardiovascular Changes ◽  
Blood Pressures ◽  
Core Body ◽  
Insight Into

The laboratory mouse is a facultative daily heterotherm in that it experiences bouts of torpor under caloric restriction. Mice are the most frequently studied laboratory mammal, and often, genetically modified mice are used to investigate many physiological functions related to weight loss and caloric intake. As such, research documenting the cardiovascular changes during fasting-induced torpor in mice is warranted. In the current study, C57BL/6 mice were implanted either with EKG/temperature telemeters or blood pressure telemeters. Upon fasting and exposure to an ambient temperature (Ta) of 19°C, mice entered torpor bouts as assessed by core body temperature (Tb). Core Tb fell from 36.6 ± 0.2°C to a minimum of 25.9 ± 0.9°C during the fast, with a concomitant fall in heart rate from 607 ± 12 beats per minute (bpm) to a minimum of 158 ± 20 bpm. Below a core Tb of 31°C, heart rate fell exponentially with Tb, and the Q10 was 2.61 ± 0.18. Further, mice implanted with blood pressure telemeters exhibited similar heart rate and activity profiles as those implanted with EKG/temperature telemeters, and the fall in heart rate and core Tb during entrance into torpor was paralleled by a fall in blood pressure. The minimum systolic, mean, and diastolic blood pressures of torpid mice were 62.3 ± 10.2, 51.9 ± 9.2, 41.0 ± 7.5 mmHg, respectively. Torpid mice had a significantly lower heart rate (25–35%) than when euthermic at mean arterial pressures from 75 to 100 mmHg, suggesting that total peripheral resistance is elevated during torpor. These data provide new and significant insight into the cardiovascular adjustments that occur in torpid mice.

scholarly journals The Impact of Central and Peripheral Cyclooxygenase Enzyme Inhibition on Exercise-Induced Elevations in Core Body Temperature

2017 ◽  
Vol 12 (5) ◽  
pp. 662-667 ◽  
Author(s):  
Matthijs T.W. Veltmeijer ◽  
Dineke Veeneman ◽  
Coen C.C.W. Bongers ◽  
Mihai G. Netea ◽  
Jos W. van der Meer ◽  
...  
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Skin Temperature ◽  
Core Body Temperature ◽  
Exercise Tests ◽  
Hypothalamic Temperature ◽  
Set Point ◽  
Exercise Induced ◽  
Core Body ◽  
The Impact

Purpose:Exercise increases core body temperature (TC) due to metabolic heat production. However, the exercise-induced release of inflammatory cytokines including interleukin-6 (IL-6) may also contribute to the rise in TC by increasing the hypothalamic temperature set point. This study investigated whether the exercise-induced increase in TC is partly caused by an altered hypothalamic temperature set point.Methods:Fifteen healthy, active men age 36 ± 14 y were recruited. Subjects performed submaximal treadmill exercise in 3 randomized test conditions: (1) 400 mg ibuprofen and 1000 mg acetaminophen (IBU/APAP), (2) 1000 mg acetaminophen (APAP), and (3) a control condition (CTRL). Acetaminophen and ibuprofen were used to block the effect of IL-6 at a central and peripheral level, respectively. TC, skin temperature, and heart rate were measured continuously during the submaximal exercise tests.Results:Baseline values of TC, skin temperature, and heart rate did not differ across conditions. Serum IL-6 concentrations increased in all 3 conditions. A significantly lower peak TC was observed in IBU/APAP (38.8°C ± 0.4°C) vs CTRL (39.2°C ± 0.5°C, P = .02) but not in APAP (38.9°C ± 0.4°C) vs CTRL. Similarly, a lower ΔTC was observed in IBU/APAP (1.7°C ± 0.3°C) vs CTRL (2.0°C ± 0.5°C, P < .02) but not in APAP (1.7°C ± 0.5°C) vs CTRL. No differences were observed in skin temperature and heart-rate responses across conditions.Conclusions:The combined administration of acetaminophen and ibuprofen resulted in an attenuated increase in TC during exercise compared with a CTRL. This observation suggests that a prostaglandin-E2-induced elevated hypothalamic temperature set point may contribute to the exercise-induced rise in TC.

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