scholarly journals Canine hyperthermia with cerebral protection

1976 ◽  
Vol 40 (4) ◽  
pp. 543-548 ◽  
Author(s):  
R. W. Carithers ◽  
R. C. Seagrave
Keyword(s):  
Core Temperature ◽  
Cold Water ◽  
Brain Temperature ◽  
Body Core Temperature ◽  
Whole Body ◽  
Similar Time ◽  
Data Points ◽  
Body Core ◽  
Heat Transfer System ◽  
The Brain

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.

Computational model for calculating body-core temperature elevation in rabbits due to whole-body exposure at 2.45 GHz

2008 ◽  
Vol 53 (12) ◽  
pp. 3391-3404 ◽  
Author(s):  
Akimasa Hirata ◽  
Hironori Sugiyama ◽  
Masami Kojima ◽  
Hiroki Kawai ◽  
Yoko Yamashiro ◽  
...  
Keyword(s):  
Computational Model ◽  
Core Temperature ◽  
Body Core Temperature ◽  
Whole Body ◽  
Temperature Elevation ◽  
Body Core

Restoration of thermoregulation after exercise

2017 ◽  
Vol 122 (4) ◽  
pp. 933-944 ◽  
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.

scholarly journals Selective brain hypothermia: feasibility and safety study of a novel method in five patients

Perfusion ◽  
2019 ◽  
Vol 35 (2) ◽  
pp. 96-103 ◽  
Author(s):  
Seyed Mohammad Seyedsaadat ◽  
Silvana F Marasco ◽  
David J Daly ◽  
Robin McEgan ◽  
James Anderson ◽  
...  
Keyword(s):  
Cardiopulmonary Bypass ◽  
Brain Temperature ◽  
The Body ◽  
Body Core Temperature ◽  
Safety Study ◽  
Cardiopulmonary Function ◽  
Cooling Fluid ◽  
Body Core ◽  
Novel Method ◽  
The Brain

Background/objective: Reduction of brain temperature remains the most common method of neuroprotection against ischemic injury employed during cardiac surgery. However, cooling delivered via the cardiopulmonary bypass circuit is brief and cooling the body core along with the brain has been associated with a variety of unwanted effects. This study investigated the feasibility and safety of a novel selective brain cooling approach to induce rapid, brain-targeted hypothermia independent of the cardiopulmonary bypass circuit. Methods: This first-in-human feasibility study enrolled five adults undergoing aortic valve replacement with cardiopulmonary bypass support. During surgery, the NeuroSave system circulated chilled saline within the pharynx and upper esophagus. Brain and body core temperature were continuously monitored. Adverse effects, cardiopulmonary function, and device function were noted. Results: Patient 1 received cooling fluid for an insignificant period, and Patients 2-5 successfully underwent the cooling procedure using the NeuroSave system for 56-89 minutes. Cooling fluid was 12°C for Patients 1-3, 6°C for Patient 4, and 2°C for Patient 5. There were no NeuroSave-related adverse events and no alterations in cardiopulmonary function during NeuroSave use. Brain temperature decreased by 3°C within 15 minutes and remained at least 3.5°C colder than the body core. During a brief episode of hypotension in one patient, the brain cooled an additional 4°C in 2 minutes, briefly reaching 27.4°C. Conclusion: The NeuroSave system can induce rapid brain-targeted hypothermia and simultaneously maintain a favorable body–brain temperature gradient, even during hypotension. Further studies are required to evaluate the function of the system during longer periods of use.

Keeping a Cool Head

Physiology ◽  
1986 ◽  
Vol 1 (2) ◽  
pp. 41-44 ◽  
Author(s):  
M Cabanac
Keyword(s):  
Heat Stress ◽  
Core Temperature ◽  
Heat Exchangers ◽  
The Body ◽  
Body Core Temperature ◽  
Mammalian Brain ◽  
Poor Tolerance ◽  
Selective Cooling ◽  
Body Core ◽  
The Brain

The mammalian brain has poor tolerance to increased temperature. However, when body core temperature rises during exercise or heat stress, the temperature of the brain can remain at a lower level, somewhat independent of the rest of the body. In several mammals the cooling of the brain is related to anatomically well-defined countercurrent heat exchangers. Humans lack these distinct anatomic structures, but significant cooling of the brain can nevertheless occur. Such selective cooling of the brain may have important medical implicantions.

Intracerebral Temperature in Neurosurgical Patients

Neurosurgery ◽  
1991 ◽  
Vol 28 (5) ◽  
pp. 709-713 ◽  
Author(s):  
Pekka Mellergård ◽  
Carl-Henrik Nordström
Keyword(s):  
Rectal Temperature ◽  
Clinical Judgment ◽  
Brain Temperature ◽  
Mean Value ◽  
Body Core Temperature ◽  
Severe Condition ◽  
Neurosurgical Patients ◽  
Body Core ◽  
The Difference ◽  
The Brain

Abstract Recent laboratory results have indicated that the ischemic brain is very sensitive to minor variations in temperature. This has created new interest in hypothermia and brain temperature. There is, however, very little information available regarding human intracerebral temperature and its relation to body core temperature during normal and pathological circumstances. We therefore made continuous measurements of the temperature of the lateral ventricle in 15 neurosurgical patients utilizing a newly developed technique with copper-constantan thermocouples introduced through a plastic catheter also used for monitoring intracranial pressure. The intraventricular temperature was higher than the rectal temperature during approximately 90% of all measurements. The largest temperature gradient measured was 2.3°C. Usually the difference between the temperature of the rectum and the brain was much smaller, the mean value being 0.33°C. For the patients in the most severe condition, the rectal temperature was sufficiently close to the brain temperature to afford a reliable basis for adequate clinical judgment.

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

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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