The relationship between directly measured human cerebral and tympanic temperatures during changes in brain temperatures (original) (raw)
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Brain temperature, body core temperature, and intracranial pressure in acute cerebral damage
Journal of Neurology, Neurosurgery & Psychiatry, 2001
Objectives-To assess the frequency of hyperthermia in a population of acute neurosurgical patients; to assess the relation between brain temperature (ICT) and core temperature (Tc); to investigate the eVect of changes in brain temperature on intracranial pressure (ICP). Methods-The study involved 20 patients (10 severe head injury, eight subarachnoid haemorrhage, two neoplasms) with median Glasgow coma score (GCS) 6. ICP and ICT were monitored by an intraventricular catheter coupled with a thermistor. Internal Tc was measured in the pulmonary artery by a Swan-Ganz catheter. Results-Mean ICT was 38.4 (SD 0.8) and mean Tc 38.1 (SD 0.8)°C; 73% of ICT and 57.5% of Tc measurements were >38°C. The mean diVerence between ICT and Tc was 0.3 (SD 0.3)°C (range −0.7 to 2.3°C) (p=0. 0001). Only in 12% of patients was Tc higher than ICT. The main reason for the diVerences between ICT and Tc was body core temperature: the diVerence between ICT and Tc increased significantly with body core temperature and fell significantly when this was lowered. The mean gradient between ICT and Tc was 0.16 (SD 0.31)°C before febrile episodes (ICT being higher than Tc), and 0.41 (SD 0.38)°C at the febrile peak (p<0.05). When changes in temperature were considered, ICT had a profound influence on ICP. Increases in ICT were associated with a significant rise in ICP, from 14.9 (SD 7.9) to 22 (SD 10.4) mm Hg (p<0.05). As the fever ebbed there was a significant decrease in ICP, from 17.5 (SD 8.62) to 16 (SD 7.76) mm Hg (p=0.02). Conclusions-Fever is extremely frequent during acute cerebral damage and ICT is significantly higher than Tc. Moreover, Tc may underestimate ICT during the phases when temperature has the most impact on the intracranial system because of the close association between increases in ICT and ICP. (J Neurol Neurosurg Psychiatry 2001;71:448-454)
Brain temperature and its fundamental properties: a review for clinical neuroscientists
Brain temperature, as an independent therapeutic target variable, has received increasingly intense clinical attention. To date, brain hypothermia represents the most potent neuroprotectant in laboratory studies. Although the impact of brain temperature is prevalent in a number of common human diseases including: head trauma, stroke, multiple sclerosis, epilepsy, mood disorders, headaches, and neurodegenerative disorders, it is evident and well recognized that the therapeutic application of induced hypothermia is limited to a few highly selected clinical conditions such as cardiac arrest and hypoxic ischemic neonatal encephalopathy. Efforts to understand the fundamental aspects of brain temperature regulation are therefore critical for the development of safe, effective, and pragmatic clinical treatments for patients with brain injuries. Although centrally-mediated mechanisms to maintain a stable body temperature are relatively well established, very little is clinically known about brain temperature's spatial and temporal distribution, its physiological and pathological fluctuations, and the mechanism underlying brain thermal homeostasis. The human brain, a metabolically "expensive" organ with intense heat production, is sensitive to fluctuations in temperature with regards to its functional activity and energy efficiency. In this review, we discuss several critical aspects concerning the fundamental properties of brain temperature from a clinical perspective.
Brain surface temperature under a craniotomy
Journal of Neurophysiology, 2012
Many neuroscientists access surface brain structures via a small cranial window, opened in the bone above the brain region of interest. Unfortunately this methodology has the potential to perturb the structure and function of the underlying brain tissue. One potential perturbation is heat loss from the brain surface, which may result in local dysregulation of brain temperature. Here, we demonstrate that heat loss is a significant problem in a cranial window preparation in common use for electrical recording and imaging studies in mice. In the absence of corrective measures, the exposed surface of the neocortex was at ∼28°C, ∼10°C below core body temperature, and a standing temperature gradient existed, with tissue below the core temperature even several millimeters into the brain. Cooling affected cellular and network function in neocortex and resulted principally from increased heat loss due to convection and radiation through the skull and cranial window. We demonstrate that const...
Clinical review: Brain-body temperature differences in adults with severe traumatic brain injury
Critical Care, 2013
Surrogate or 'proxy' measures of brain temperature are used in the routine management of patients with brain damage. The prevailing view is that the brain is 'hotter' than the body. The polarity and magnitude of temperature diff erences between brain and body, however, remains unclear after severe traumatic brain injury (TBI). The focus of this systematic review is on the adult patient admitted to intensive/neurocritical care with a diagnosis of severe TBI (Glasgow Coma Scale score of less than 8). The review considered studies that measured brain temperature and core body temperature. Articles published in English from the years 1980 to 2012 were searched in databases, CINAHL, PubMed, Scopus, Web of Science, Science Direct, Ovid SP, Mednar and ProQuest Dissertations & Theses Database. For the review, publications of randomised controlled trials, non-randomised controlled trials, before and after studies, cohort studies, case-control studies and descriptive studies were considered for inclusion. Of 2,391 records identifi ed via the search strategies, 37 were retrieved for detailed examination (including two via hand searching). Fifteen were reviewed and assessed for methodological quality. Eleven studies were included in the systematic review providing 15 brain-core body temperature comparisons. The direction of mean brain-body temperature diff erences was positive (brain higher than body temperature) and negative (brain lower than body temperature). Hypothermia is associated with large brain-body temperature diff erences. Brain temperature cannot be predicted reliably from core body temperature. Concurrent monitoring of brain and body temperature is recommended in patients where risk of temperature-related neuronal damage is a cause for clinical concern and when deliberate induction of below-normal body temperature is instituted.
Deep-forehead” temperature correlates well with blood temperature
Canadian Journal of Anaesthesia-journal Canadien D Anesthesie, 2000
Purpose: To evaluate the accuracy and precision of “deep-forehead” temperature with rectal, esophageal, and tympanic membrane temperatures, compared with blood temperature. Methods: We studied 41 ASA physical status 1 or 2 patients undergoing abdominal and thoracic surgery scheduled to require at least three hours. “Deep-forehead” temperature was measured using a Coretemp® thermometer (Terumo, Tokyo, Japan). Blood temperature was measured with a thermistor of a pulmonary artery. Rectal, tympanic membrane, and distal esophageal temperatures were measured with thermocouples. All temperatures were recorded at 20 min intervals after the induction of anesthesia. We considered blood temperature as the reference value. Temperatures at the other four sites were compared with blood temperature using correlation, regression, and Bland and Altman analyses. We determined accuracy (mean difference between reference and test temperatures) and precision (standard deviation of the difference) of 0.5°C to be clinically acceptable. Results: “Deep-forehead” temperature correlated well with blood temperature as well as other temperatures, the determination coefficients (r 2) being 0.85 in each case. The bias for the “deep-forehead” temperature was 0.0°C which was the same as tympanic membrane temperature and was smaller than rectal and esophageal temperatures. The standard deviation of the differences for the “deep-forehead” temperature was 0.3°C, which was the same as rectal temperature. Conclusions: We have demonstrated that the “deep-forehead” temperature has excellent accuracy and clinically sufficient precision as well as other three core temperatures, compared with blood temperature. Objectif: Évaluer l’exactitude et la précision de la température frontale «cutanée profonde» et les températures rectale, œsophagienne et tympanique, comparées à la température du sang. Méthode: L’étude a porté sur 41 patients d’état physique ASA I ou II devant subir une intervention chirurgicale abdominale et thoracique d’au moins deux heurs. La température «cutanée profonde» a été mesurée à l’aide du thermomètre Coretemp® (Terumo, Tokyo, Japon). Celle du sang a été prise avec une thermistance d’une artère pulmonaire et les températures rectale, tympanique et œsophagienne distale, avec des thermocouples. Elles ont toutes été enregistrées à 20 min d’intervalle après l’induction de l’anesthésie. La température du sang a servi de référence. Les températures des quatre autres sites ont été comparées avec celle du sang à l’aide d’analyses de corrélation, de régression et des analyses de Bland et Altman. Nous avons reconnu une exactitude (différence moyenne entre la température de référence et les autres) et une précision (écart type de la différence) de 0,5 °C près comme une différence acceptable en clinique. Résultats: La température «cutanée profonde» était en corrélation avec celle du sang, et avec celle des autres sites, le cofficient de détermination (r 2) étant de 0,85 dans chaque cas. Le biais de la température «cutanée profonde» était de 0,0 °C, comme celui de la température tympanique, et plus faible que ceux des températures rectale et œsophagienne. L’écart type de la différence pour la température «cutanée profonde» était de 0,3 °C, comme pour la température rectale. Conclusion: Nous avons démontré que la température frontale pronfonde présentait une grande exactitude et une précision utile suffisante, autant que les trois autres températures centrales, comparée à la température du sang.
Intracerebral temperature monitoring in severely head injured patients
Acta Neurochirurgica, 1995
In a series of 6 severely head injured patients, intraventricular as well as rectal, bladder and jugular vein temperature is recorded. The relationship between these temperatures in different conditions is evaluated. Intracerebral temperature is 0.5 +0.2~ (mean + SD) higher than bladder temperature except in conditions such as brain death. It is concluded that rectal temperature is not representative and therefore not a good alternative to the measurement of brain temperature. More data on human intracerebral temperature are mandatory as well as prospective studies correlating intracerebral temperature with final outcome in head injury.
Critical Care, 2009
Introduction Temperature measurement is important during routine neurocritical care especially as differences between brain and systemic temperatures have been observed. The purpose of the study was to determine if infra-red temporal artery thermometry provides a better estimate of brain temperature than tympanic membrane temperature for patients with severe traumatic brain injury. Methods Brain parenchyma, tympanic membrane and temporal artery temperatures were recorded every 15-30 min for five hours during the first seven days after admission. Results Twenty patients aged 17-76 years were recruited. Brain and tympanic membrane temperature differences ranged from-0.8 °C to 2.5 °C (mean 0.9 °C). Brain and temporal artery temperature differences ranged from-0.7 °C to 1.5 °C (mean 0.3 °C). Tympanic membrane temperature differed from brain temperature by an average of 0.58 °C more than temporal artery temperature measurements (95% CI 0.31 °C to 0.85 °C, P < 0.0001). Conclusions At temperatures within the normal to febrile range, temporal artery temperature is closer to brain temperature than is tympanic membrane temperature.
Temperature Changes in the Brain of Patients Undergoing MRI Examination
International Journal of Sciences: Basic and Applied Research, 2013
Magnetic Resonance Imaging scanners have become important tools in modern day health care. During the imaging process, total radiofrequency power is transferred from the RF coil to the brain tissues resulting in increase in temperature in the subject being imaged. Currently, reliable and validated means to predict RF heating are not unavailable.This research was conducted to determine temperature changes in the human brain during MRI examination.This study was carried out at two MRI Units in Ghana. One hundred and twenty-six patients were investigated. Data collected include preand post-scan tympanic temperatures and specific absorption rates values. The average preand post-scan tympanic temperatures measured for Centre A were 36.5±0.1 °C and 37.0±0.1 °C respectively with an average change in temperature of 0.5±0.1 °C for 30.68 minutes scan and an average SAR value of 1.25 W/kg. Centre B measured average preand post-scan tympanic temperatures of 36.4±0.1 °C and 36.8±0.1 °C respectiv...
Natural selective cooling of the human brain: evidence of its occurrence and magnitude
The Journal of Physiology, 1979
1. The technique of perceptual rating of thermal stimuli was used, in eight human subjects immersed in warm water, in order to appreciate whether they were hypo-, normoor hyperthermic. Oesophageal, tympanic and forehead skin temperatures were recorded, as also was the temperature of the skin above the angularis oculi vein.
International Journal of Statistics in Medical Research, 2013
There is uncertainty about the reliability of using body temperature readings as a 'surrogate' measure of brain temperature. Aim: To determine the temporal interrelationship between body and brain temperature after severe traumatic brain injury (TBI). Setting and Patients: Large University teaching hospital in the North West of England. Patients admitted for emergency neurocritical care. All patients received dual-modality monitoring of brain tissue pressure and temperature via invasive intracerebral micro-sensors. Body temperature was measured using an indwelling thermistor inserted in to the rectum. Methods: Temperature was monitored continuously with values stored to a bedside data acquisition system at intervals of 10 minutes. Data were transferred to a spreadsheet at end of each individual's monitoring period for further analysis under Matlab routines. The method of functional principal components was used to determine the time-dynamics of brain and body temperature relationships. Results: In the period after severe TBI, median body and brain temperature for all readings and in all patients was 37.6 o C and 37.7 o C respectively; a statistical (p <0.001) but not clinically significant difference. A strong regression relationship between brain and body temperature was demonstrated (functional coefficient of determination, R 2 = 0.7623, p< 0.0020). Conclusions: Body temperature is a good early predictor of brain temperature but only during the first two days after severe TBI. The results will be of value for future predictive modeling of brain temperature changes, particularly where brain tissue monitoring is not clinically justified or available. In particular, results demonstrate the uncertainty in using body temperature as a surrogate for brain temperature beyond the first two days after severe traumatic brain injury.