Intracranial temperature recordings in human subjects. The contribution of the neurosurgeon to thermal physiology

Mariak, Zenon

doi:10.1016/s0306-4565(01)00087-0

Cited by 22 publications

(19 citation statements)

References 38 publications

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“…In clinical studies applying LH, temperature monitoring is not standardized (Hachimi-Idrissi et al, 2001;Liu et al, 2006). Under pathological conditions, the temperature of the brain tissue are insufficiently represented by the trunk core or the tympanic temperature (Mariak, 2002;Mellergard and Nordström, 1990). Our results suggest, that the ideal reference point for temperature monitoring to control the success of LH is at least 2 cm below the cortical surface.…”

Section: Discussionmentioning

confidence: 84%

Theoretical evaluations of therapeutic systemic and local cerebral hypothermia

Keller

Mudra²,

Gugl

et al. 2009

Journal of Neuroscience Methods

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Section: Discussionmentioning

confidence: 84%

Theoretical evaluations of therapeutic systemic and local cerebral hypothermia

Keller

Mudra²,

Gugl

et al. 2009

Journal of Neuroscience Methods

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“…But this does not significantly affect brain temperature because more efficient heat removal is provided by higher CBF, the dominant effect in temperature regulation. Thus cerebral metabolic activity does not markedly affect brain temperature, and, indeed, it has been reported that patients in whom cerebral metabolism was reduced to 55% of normal did not show a larger brain-rectal temperature difference (15). A corollary is that body temperature is the primary determinant of deep brain temperature.…”

Section: Discussionmentioning

confidence: 90%

How the body controls brain temperature: the temperature shielding effect of cerebral blood flow

Zhu¹,

Ackerman²,

Sukstanskiı̆³

et al. 2006

Journal of Applied Physiology

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. How the body controls brain temperature: the temperature shielding effect of cerebral blood flow. J Appl Physiol 101: [1481][1482][1483][1484][1485][1486][1487][1488] 2006. First published July 13, 2006; doi:10.1152/japplphysiol.00319.2006.-Normal brain functioning largely depends on maintaining brain temperature. However, the mechanisms protecting brain against a cooler environment are poorly understood. Reported herein is the first detailed measurement of the brain-temperature profile. It is found to be exponential, defined by a characteristic temperature shielding length, with cooler peripheral areas and a warmer brain core approaching body temperature. Direct cerebral blood flow (CBF) measurements with microspheres show that the characteristic temperature shielding length is inversely proportional to the square root of CBF in excellent agreement with a theoretical model. This "temperature shielding effect" quantifies the means by which CBF prevents "extracranial cold" from penetrating deep brain structures. The effect is crucial for research and clinical applications; the relationship between brain, body, and extracranial temperatures can now be quantitatively predicted.brain temperature regulation; cerebral metabolism; hypothermia; bioheat equation BLOOD FLOW SERVES VARIOUS roles in brain functioning. It delivers nutrients, removes waste products and, importantly, supports brain temperature regulation. Indeed, the temperature of incoming arterial blood is the main determinant of the brain temperature (9). Although this is correct for deep brain structures, it is not clear how the temperature distribution in superficial brain structures depends on the extracranial temperature. How deeply an external "cold assault" penetrates into the functioning brain remains an open question. This issue is especially important because of numerous current attempts to use mild hypothermia for treatment of stroke, multiple sclerosis, and other brain injuries (see, for example, Refs. 6,[10][11][12]17,23,24). Therapeutic results have been conflicting, in large part because quantifying the resultant cooling of human brain in vivo is beyond current technology. Therefore, developing a biophysical framework describing the determinants of heat flow, thus temperature regulation, in human brain would be a substantial achievement. Within such a framework one could predict the brain temperature response, or lack thereof, to external devices designed to impose mild hypothermia. Herein we report experimental measurements of the brain temperature profile that together with theoretical considerations quantitatively establish a general phenomenon: the temperature shielding effect of blood flow, which is responsible for brain protection against external cooling.Major mechanisms responsible for body temperature regulation in mammals are well known (see, for example, Ref. 28). In our experiments, the body temperature was kept constant by circulating warm water as described in MATERIALS AND METHODS. Blood flow acts as a heat exchanger with pip...

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“…They discussed that regional heat flow is probably the most powerful factor influencing tympanic temperature because the local metabolism of the tympanic membrane should have only a very small influence on tympanic temperature; the vascularization of tympanic membrane is not homogeneous; and the blood supply is poorest in its deepest region. Since the human brain is known to produce 20 times more heat than other tissues at rest, excluding kidney, heart, and liver 19) , the excessive heat from the head needs to be removed and dissipated to avoid any excessive increase in brain temperature 17) . Herein, it is reasonable to assume that the temperature of the surrounding ear canal wall reaches values similar to that of the tympanic membrane when the subject's head is encapsulated by the vapor impermeable PVC hood.…”

Section: Discussionmentioning

confidence: 99%

“…It seems that the higher IR T ty than T re in the present study was attributed to the protective hood over the head that inhibited heat loss from the human head at T a of 32°C or during exercise. Despite long arguments on the validity of T ty as a thermal index, there are reports that T ty followed brain temperature more closely than the rectal temperature 17) , and T ty was consistent to the patterns of the brain temperature but T re was abandoned as unpredictable in their relation to temperature in the cranium temperature 9) . Given findings from present and previous studies, the following conclusion could be drawn: IR T ty is a valid index to reflect the thermal burden of workers wearing impermeable protective clothing with a hood in heat.…”

Section: Discussionmentioning

confidence: 99%

“…Because of its anatomical proximity to the hypothalamus, it is reported that tympanic temperature follows brain temperature more closely than rectal temperature or esophageal temperature 16,17) . Even though some have doubted that tympanic thermometry is sufficiently accurate to measure core temperature 18) , there are also many reports that tympanic temperature is a good index of core temperature when measured accurately [19][20][21] .…”

Section: Introductionmentioning

confidence: 99%

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Validity of Infrared Tympanic Temperature for the Evaluation of Heat Strain While Wearing Impermeable Protective Clothing in Hot Environments

et al. 2011

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The purpose of this study was to investigate the validity of infrared tympanic temperature (IR T ty ) as a thermal index to evaluate the heat strain of workers in hot environments, in comparison with rectal temperatures at various depths (T re-4, -8, and -16 for 4, 8 and 16 cm from the anal sphincter). Eight males underwent twelve experimental conditions: two activities (rest and exercise) × three clothing levels [Control, HDPE (high-density polyethylene coverall) and PVC (polyvinyl chloride coverall) condition] × two air temperatures (25 and 32°C with 50%RH). The results showed that 1) in the conditions with most heat strain (HDPE or PVC condition at 32°C), IR T ty was equal to or even higher than T re ; 2) during exercise, physiological strain index (PSI) using IR T ty did not underestimate PSI-values using T re-16 , and overestimated those PSI-values from T re-16 in HDPE and PVC conditions at 32°C; 3) during exercise, the relationships between IR T ty and heart and total sweat rate were stronger than those between T re-16 and heart and total sweat rate. These results indicated that IR T ty is valid as a thermal index to evaluate the heat strain of workers wearing impermeable protective coveralls in hot environments. However, the application of IR T ty is limited only for strenuous works wearing encapsulated personal protective clothing with a hood in heat.

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Intracranial temperature recordings in human subjects. The contribution of the neurosurgeon to thermal physiology

Cited by 22 publications

References 38 publications

Theoretical evaluations of therapeutic systemic and local cerebral hypothermia

Theoretical evaluations of therapeutic systemic and local cerebral hypothermia

How the body controls brain temperature: the temperature shielding effect of cerebral blood flow

Validity of Infrared Tympanic Temperature for the Evaluation of Heat Strain While Wearing Impermeable Protective Clothing in Hot Environments

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