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Core Temperature (core + temperature)
Selected AbstractsORIGINAL ARTICLE: A randomised single blinded study of the administration of pre-warmed fluid vs active fluid warming on the incidence of peri-operative hypothermia in short surgical procedures,ANAESTHESIA, Issue 9 2010J. C. Andrzejowski Summary We compared the effect of delivering fluid warmed using two methods in 76 adult patients having short duration surgery. All patients received a litre of crystalloid delivered either at room temperature, warmed using an in-line warming device or pre-warmed in a warming cabinet for at least 8 h. The tympanic temperature of those receiving fluid at room temperature was 0.4 °C lower on arrival in recovery when compared with those receiving fluid from a warming cabinet (p = 0.008). Core temperature was below the hypothermic threshold of 36.0 °C in seven (14%) patients receiving either type of warm fluid, compared to eight (32%) patients receiving fluid at room temperature (p = 0.03). The administration of 1 l warmed fluid to patients having short duration general anaesthesia results in higher postoperative temperatures. Pre-warmed fluid, administered within 30 min of its removal from a warming cabinet, is as efficient at preventing peri-operative hypothermia as that delivered through an in-line warming system. [source] Cerebral oxygenation is reduced during hyperthermic exercise in humansACTA PHYSIOLOGICA, Issue 1 2010P. Rasmussen Abstract Aim:, Cerebral mitochondrial oxygen tension (PmitoO2) is elevated during moderate exercise, while it is reduced when exercise becomes strenuous, reflecting an elevated cerebral metabolic rate for oxygen (CMRO2) combined with hyperventilation-induced attenuation of cerebral blood flow (CBF). Heat stress challenges exercise capacity as expressed by increased rating of perceived exertion (RPE). Methods:, This study evaluated the effect of heat stress during exercise on PmitoO2 calculated based on a Kety-Schmidt-determined CBF and the arterial-to-jugular venous oxygen differences in eight males [27 ± 6 years (mean ± SD) and maximal oxygen uptake (VO2max) 63 ± 6 mL kg,1 min,1]. Results:, The CBF, CMRO2 and PmitoO2 remained stable during 1 h of moderate cycling (170 ± 11 W, ,50% of VO2max, RPE 9,12) in normothermia (core temperature of 37.8 ± 0.4 °C). In contrast, when hyperthermia was provoked by dressing the subjects in watertight clothing during exercise (core temperature 39.5 ± 0.2 °C), PmitoO2 declined by 4.8 ± 3.8 mmHg (P < 0.05 compared to normothermia) because CMRO2 increased by 8 ± 7% at the same time as CBF was reduced by 15 ± 13% (P < 0.05). During exercise with heat stress, RPE increased to 19 (19,20; P < 0.05); the RPE correlated inversely with PmitoO2 (r2 = 0.42, P < 0.05). Conclusion:, These data indicate that strenuous exercise in the heat lowers cerebral PmitoO2, and that exercise capacity in this condition may be dependent on maintained cerebral oxygenation. [source] Dietary phytoestrogens improve stroke outcome after transient focal cerebral ischemia in ratsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2006María C. Burguete Abstract As phytoestrogens are postulated as being neuroprotectants, we assessed the hypothesis that dietary isoflavone-type phytoestrogens are neuroprotective against ischemic stroke. Transient focal cerebral ischemia (90 min) was induced by middle cerebral artery occlusion (MCAO) following the intraluminal thread technique, both in rats fed with soy-based diet and in rats fed with isoflavone-free diet. Cerebro-cortical laser-Doppler flow (cortical perfusion, CP), arterial blood pressure, core temperature, PaO2, PaCO2, pH and glycemia were measured before, during and after MCAO. Neurological examination and infarct volume measurements were carried out 3 days after the ischemic insult. Dietary isoflavones (both glycosides and aglycones) were measured by high-performance liquide chromatography. Neither pre-ischemic, intra-ischemic nor post-ischemic CP values were significantly different between the soy-based diet and the isoflavone-free diet groups. Animals fed with the soy-based diet showed an infarct volume of 122 ± 20.2 mm3 (19 ± 3.3% of the whole ipsilateral hemisphere volume). In animals fed with the isoflavone-free diet the mean infarct volume was significantly higher, 191 ± 26.7 mm3 (28 ± 4.1%, P < 0.05). Neurological examination revealed significantly higher impairment in the isoflavone-free diet group compared with the soy-based diet group (3.3 ± 0.5 vs. 1.9 ± 0.5, P < 0.05). These results demonstrate that dietary isoflavones improve stroke outcome after transient focal cerebral ischemia in such a way that a higher dietary isoflavone content results in a lower infarct volume and a better neurological status. [source] Effects of induced hyperthermia on pharmacokinetics of ropivacaine in ratsFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 4 2010Romain Guilhaumou Abstract Ropivacaine is a local anaesthetic used for epidural anaesthesia and postoperative pain relief. Hyperthermia is a very common sign of infection associated with variations in physiological parameters, which may influence drugs pharmacokinetics. The aim of this study was to determine the effects of induced hyperthermia on ropivacaine pharmacokinetics in rats. Two groups of six rats were given a single subcutaneous ropivacaine injection. Hyperthermia-induced animals were placed in a water bath to obtain a stable mean core temperature of 39.7 °C. After blood samples collection, ropivacaine serum concentrations and pharmacokinetic parameters were determined. Two other groups of six rats were sacrificed 30 min after ropivacaine injection to determine serum and tissues (brain and heart) concentrations. Our results (median ± inter quartile range) reveal a significant increase of the total apparent clearance (0.0151 ± 0.000800 L/min vs. 0.0134 ± 0.00134 L/min), apparent volume of distribution (Vd) (2.19 ± 0.27 L vs. 1.57 ± 0.73 L) and a significant decrease in exposure (488 ± 50.6 mg.min/L vs. 572 ± 110 mg.min/L) in induced-hyperthermia group. We observed a significant increase in brain ropivacaine concentration in hyperthermic rats (8.39 ± 8.42 ,g/g vs. 3.48 ± 3.26 ,g/g) and no significant difference between cardiac concentrations in the two groups (5.38 ± 4.83 ,g/g vs. 3.73 ± 2.44 ,g/g). Results suggest a higher tissular distribution of ropivacaine and an increase in blood,brain barrier permeability during hyperthermia. The hyperthermia-induced increase in Vd could be responsible for an increase in cerebral ropivacaine toxicity. These experimental data provide a basis for future clinical investigations in relation to local anaesthetic use in hyperthermic patients. [source] Effect on Sleep of Posterior Hypothalamus Stimulation in Cluster HeadacheHEADACHE, Issue 7 2007Roberto Vetrugno MD Objective.,To evaluate the structure and quality of sleep and the circadian rhythm of body core temperature (BcT°) in patients with drug-resistant chronic cluster headache (CH) before and during deep brain stimulation (DBS) of the posterior hypothalamus. Background.,Chronic CH is a severe primary headache and frequently associated with disturbances in sleep. Posterior hypothalamus DBS is performed as an effective treatment of drug-resistant chronic CH. The effects of posterior hypothalamus DBS on sleep and the circadian rhythm of BcT° are unknown. Methods.,Three male patients with chronic drug-resistant CH underwent 48-hour consecutive polysomnography (PSG) by means of the VITAPORT® system with determination of BcT° by means of a rectal probe. Recordings were done before electrode implantation in the posterior hypothalamus and after optimized DBS of posterior hypothalamus. Results.,Before electrode implantation PSG showed nocturnal CH attacks, reduced sleep efficiency, fragmented sleep and increased periodic limb movements in sleep (PLMS). During DBS nocturnal CH attacks were abolished and sleep efficiency and PLMS improved. BcT° circadian rhythm was normal both before and during DBS. Conclusions.,Our data show that DBS of posterior hypothalamus in drug-resistant chronic CH is effective in curtailing nocturnal CH attacks, and is associated with improved sleep structure and quality. Chronic CH displays a normal circadian rhythm of BcT°, unchanged during hypothalamic DBS. [source] Prophylactic steroids for paediatric open-heart surgery: a systematic reviewINTERNATIONAL JOURNAL OF EVIDENCE BASED HEALTHCARE, Issue 4 2008Suzi Robertson-Malt BHSc PhD Background, The immune response to cardiopulmonary bypass in infants and children can lead to a series of post-operative morbidities and mortality, that is, hemodynamic instability, increased infection and tachyarrhythmias. Administration of prophylactic doses of corticosteroids is sometimes used to try and ameliorate this pro-inflammatory response. However, the clinical benefits and harms of this type of intervention in the paediatric patient remain unclear. Objectives, To systematically review the beneficial and harmful effects of the prophylactic administration of corticosteroids, compared with placebo, in paediatric open-heart surgery. Search strategy, The trials registry of the Cochrane Heart Group, the Cochrane Central Register of Controlled Trials in The Cochrane Library (Issue 4, 2006), MEDLINE (1966 to January 2007), EMBASE (1980 to January 2007) were searched. An additional hand-search of the EMRO database for Arabic literature was performed. Grey literature was searched, and experts in the field were contacted for any unpublished material. No language restrictions were applied. Selection criteria, All randomised and quasi-randomised controlled trials of open-heart surgery in the paediatric population that received corticosteroids pre-, peri- or post-operatively, with reported clinical outcomes in terms of morbidity and mortality. Data collection and analysis, Eligible studies were abstracted and evaluated by two independent reviewers. All meta-analyses were completed using RevMan4.2.8. Weighted mean difference (WMD) was the primary summary statistic with data pooled using a random-effects model. Main results, All cause mortality could not be assessed as the data reports were incomplete. There was weak evidence in favour of prophylactic corticosteroid administration for reducing intensive care unit stay, peak core temperature and duration of ventilation (WMD (95% confidence intervals) ,0.50 h (,1.41 to 0.41); ,0.20°C (,1.16 to 0.77) and ,0.63 h (,4.02 to 2.75) respectively). [source] Abstracts of the 8th Meeting of the Italian Peripheral Nerve Study Group: 84JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2003V Donadio The aim of the study is to determine the site of autonomic lesion in a patient with Holmes-Adie Syndrome (HAS) who subsequently developed generalized anhydrosis. We describe a 38-year-old woman who from age 33 showed a right pupil larger than the left and from age 34 complained of focal and, a year later, generalized anhydrosis. Neurological examination showed absent tendon reflexes and right mydriatic pupil. Brain MRI, EEG, motor and sensory conduction studies were normal. Serologic screening for autoimmune disease was negative. To determine the site of the autonomic lesion the patient underwent the following investigations: pupillary tests with a diluted solution of pilocarpine (0.062%) and adrenaline (0.1%); cardiovascular reflexes; thermoregulatory sweat test (TST); circadian rhythm of body core temperature (CRT°); sympathetic skin response (SSR); microneurography recording of skin sympathetic activity (SSA) from median and peroneal nerves, and muscle sympathetic activity (MSA) from peroneal nerve; skin biopsy to evaluated the eccrine glands. Pupillary tests showed postganglionic parasympathetic and sympathetic denervation only of the right pupil. TST showed complete anhydrosis, SSR and SSA were absent and skin biopsy revealed normal morphology of the eccrine glands with hypotrophy of their structures. These results indicated a lesion of the postganglionic skin sympathetic fibers. Mechanisms for heat loss and conservation, cardiovascular reflexes and MSA were normal excluding a hypothalamic dysfunction or a more diffuse involvement of the autonomic nervous system. In conclusion, our patient showed a HAS associated with generalized anhydrosis and the autonomic investigations suggested underlying postganglionic parasympathetic and sympathetic autonomic lesions. [source] Rhythms of Mental PerformanceMIND, BRAIN, AND EDUCATION, Issue 1 2008Pablo Valdez ABSTRACT, Cognitive performance is affected by an individual's characteristics and the environment, as well as by the nature of the task and the amount of practice at it. Mental performance tests range in complexity and include subjective estimates of mood, simple objective tests (reaction time), and measures of complex performance that require decisions to be made and priorities set. Mental performance tasks show 2 components, a circadian rhythm and the effects of time awake. The circadian rhythm is in phase with the rhythm of core temperature and there is evidence for a causal link. Increasing time awake results in performance deterioration and is attributed to fatigue. The relative contribution of these 2 components depends upon the task under consideration; simple tasks generally show smaller effects due to increasing time awake. These contributions have been assessed by constant routines and forced desynchronization protocols and have formed the basis of several mathematical models that attempt to predict performance in a variety of field conditions. Mental performance is negatively affected by sleep loss; although short naps are beneficial, sleep inertia limits their value immediately after waking. The processes involved in cognition include attention (tonic and phasic alertness, and selective and sustained attention), working memory (phonological, used for speech, reading, and writing; and visuospatial, used for spatial processing, drawing, and mathematics), and executive function (initiative, decision making, and problem solving). These processes are illuminated by analysis of the regions of the brain involved, the presence of circadian rhythmicity, and the effects of sleep loss. The results from such laboratory- and field-based observations are relevant to the issue of learning in schoolchildren and lead to suggestions for improving their performance. [source] Cardiopulmonary resuscitation after near drowning and hypothermia: restoration of spontaneous circulation after vasopressinACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 3 2003G. Sumann Recent animal data have challenged the common clinical practice to avoid vasopressor drugs during hypothermic cardiopulmonary resuscitation (CPR) when core temperature is below 30°C. In this report, we describe the case of a 19-year-old-female patient with prolonged, hypothermic, out-of-hospital cardiopulmonary arrest after near drowning (core temperature, 27°C) in whom cardiocirculatory arrest persisted despite 2 mg of intravenous epinephrine; but, immediate return of spontaneous circulation occurred after a single dose (40 IU) of intravenous vasopressin. The patient was subsequently admitted to a hospital with stable haemodynamics, and was successfully rewarmed with convective rewarming, but died of multiorgan failure 15 h later. To the best of our knowledge, this is the first report about the use of vasopressin during hypothermic CPR in humans. This case report adds to the growing evidence that vasopressors may be useful to restore spontaneous circulation in hypothermic cardiac arrest patients prior to rewarming, thus avoiding prolonged mechanical CPR efforts, or usage of extracorporeal circulation. It may also support previous experience that the combination of both epinephrine and vasopressin may be necessary to achieve the vasopressor response needed for restoration of spontaneous circulation, especially after asphyxial cardiac arrest or during prolonged CPR efforts. [source] A thousand and one nova outburstsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007Noya Epelstain ABSTRACT A full nova cycle includes mass accretion, thermonuclear runaway resulting in outburst and mass-loss, and finally, decline. Resumed accretion starts a new cycle, leading to another outburst. Multicycle nova evolution models have been calculated over the past twenty years, the number being limited by numerical constraints. Here we present a long-term evolution code that enables a continuous calculation through an unlimited number of nova cycles for an unlimited evolution time, even up to 1.5 × 1010 yr. Starting with two sets of the three independent nova parameters , the white dwarf (WD) mass, the temperature of its isothermal core, and the rate of mass transfer on to it , we have followed the evolution of two models, with initial masses of 1 M, and 0.65 M, through over 1000 and over 3000 cycles, respectively. The accretion rate was assumed constant throughout each calculation: 10,11 M, yr,1 for the 1 M, WD, and 10,9 M, yr,1 for the 0.65 M, one. The initial temperatures were taken to be relatively high: 30 × 106 and 50 × 106 K, respectively, as they are likely to be at the onset of the outburst phase. The results show that although on the short-term consecutive outbursts are almost identical, on the long-term scale the characteristics change. This is mainly due to the changing core temperature, which decreases very similarly to that of a cooling WD for a time, but at a slower rate thereafter. As the WD's mass continually decreases, since both models lose more mass than they accrete, the central pressure decreases accordingly. The outbursts on the massive WD change gradually from fast to moderately fast, and the other characteristics (velocity, abundance ratios, isotopic ratios) change, too. Very slowly, a steady state is reached, where all characteristics, both in quiescence and in outburst, remain almost constant. For the less massive WD accreting at a high rate, outbursts are similar throughout the evolution. [source] Stimulated single fiber electromyography in the mouse: Techniques and normative dataMUSCLE AND NERVE, Issue 7 2001Clifton L. Gooch MD Abstract As the number of new transgenic mouse models of human neuromuscular disease continues to increase, the development of sophisticated electrophysiologic techniques for assessing the peripheral nervous system in these models has become important. Neuromuscular junction (NMJ) dysfunction, in particular, is often not detectable by morphologic or other techniques. To enable sensitive testing of murine NMJ function, we developed and tested a method for stimulated single fiber electromyography (S-SFEMG) in the gastrocnemius muscles of anesthetized mice. Jitter was assessed by measuring the mean consecutive latency difference (MCD) of single fiber responses to sciatic nerve stimulation at 2 HZ. Mean MCD values in normothermic mice were in the range of 6,8 ,s for different strains, with no MCD values exceeding 25 ,s. Reduced core temperature (to 29°,30°C) resulted in increased jitter, whereas intubation and mechanical ventilation of mice did not alter these values. Intraperitoneal and intravenous injection of vecuronium, however, resulted in progressively increased jitter followed by blocking in continuously monitored fibers. These observations validate the utility of S-SFEMG in mice as an index of NMJ function under a variety of physiologic conditions, and suggest that a high safety factor for neuromuscular transmission exists at mouse NMJs. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 941,945, 2001 [source] Physiological and performance effects of glycerol hyperhydration and rehydrationNUTRITION REVIEWS, Issue 12 2009Simon P Van Rosendal Studies have shown that beverages containing glycerol can enhance and maintain hydration status and may improve endurance exercise performance by attenuating adverse physiological changes associated with dehydration. Improvements to performance include increased endurance time to exhaustion by up to 24%, or a 5% increase in power or work. However, some studies have found no performance benefits during either prolonged exercise or specific skill and agility tests. In studies that have shown benefits, the improvements have been associated with thermoregulatory and cardiovascular changes. These include increased plasma volume and sweat rates, as well as reduced core temperature and ratings of perceived exertion. In a very small number of subjects, glycerol consumption has been associated with side-effects including nausea, gastrointestinal discomfort, dizziness, and headaches. In summary, while glycerol and fluid ingestion results in hyperhydration, the documented benefits to exercise performance remain inconsistent. [source] Heat penetration characteristics and shelf-life studies of mushrooms in brine processed in retort pouchesPACKAGING TECHNOLOGY AND SCIENCE, Issue 4 2004V. Chandrasekar Abstract White button mushrooms were washed, blanched and cut longitudinally into two halves. 100,g mushroom halves was placed into each retort pouch and 90,ml hot brine (2% salt, 0.1% citric acid) was added. Retort pouches (105,µm thick) had an outer polyester layer (12.5,µm), a middle aluminium layer (12.5,µm) and an inner cast polypropylene layer (80,µm); pouch size was 20 × 16,cm, seal size 10,mm and lip size 4,mm. Pouches were fixed with thermocouples for recording the core temperature of the mushroom pieces, using a data recorder and a computer. After sealing and over-pressure retorting at F0 = 9.6, the pouches were stored at the ambient conditions. The heat penetration parameters were calculated. The heating curve obtained was logarithmic in nature. Sensory evaluation of mushroom curry prepared from the stored mushrooms showed that the product had high acceptability (7.9 on a scale of 10) which reduced very slightly (to 7.5) during storage for 12 months. No deformity, leakage or spoilage was noticed and the product remained sterile and acceptable even after 12 months of storage at the ambient conditions (20,30°C). Copyright © 2004 John Wiley & Sons, Ltd. [source] Chlorpyrifos-Induced Hypothermia and Vasodilation in the Tail of the Rat: Blockade by Scopolamine,BASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 1 2000Christopher J. Gordon Organophosphate pesticides such as chlorpyrifos reduce core temperature (Tc) in laboratory rodents. The mechanism(s) responsible for the chlorpyrifos-induced hypothermia are not well known. This study assessed the role of a key effector for thermoregulation in the rat, vasomotor control of heat loss from the tail, and its possible cholinergic control during chlorpyrifos-induced hypothermia. Tc and motor activity were monitored by telemetry in female Long-Evans rats maintained at an ambient temperature (Ta) of 25°. Tail skin temperature (Tsk(t)) was measured hourly. Rats were dosed with chlorpyrifos (0 or 25 mg/kg orally). Two hr later the rats were dosed with saline or scopolamine (1.0 mg/kg intraperitoneally). Two hr after chlorpyrifos treatment there was a marked elevation in Tsk(t) concomitant with a 0.5° reduction in Tc. Scopolamine administered to control rats led to a marked elevation in Tc with little change in Tsk(t). Rats treated with chlorpyrifos and administered scopolamine underwent a marked vasoconstriction and elevation in Tc. Vasodilation of the tail is an important thermoeffector to reduce Tc during the acute stages of chlorpyrifos exposure. The blockade of the response by scopolamine suggests that the hypothermic and vasodilatory response to chlorpyrifos is mediated via a cholinergic muscarinic pathway in the CNS. [source] Partial-body exposure of human volunteers to 2450,MHz pulsed or CW fields provokes similar thermoregulatory responses,BIOELECTROMAGNETICS, Issue 4 2001Eleanor R. Adair Abstract Many reports describe data showing that continuous wave (CW) and pulsed (PW) radiofrequency (RF) fields, at the same frequency and average power density (PD), yield similar response changes in the exposed organism. During whole-body exposure of squirrel monkeys at 2450 MHz CW and PW fields, heat production and heat loss responses were nearly identical. To explore this question in humans, we exposed two different groups of volunteers to 2450,MHz CW (two females, five males) and PW (65,,s pulse width, 104,pps; three females, three males) RF fields. We measured thermophysiological responses of heat production and heat loss (esophageal and six skin temperatures, metabolic heat production, local skin blood flow, and local sweat rate) under a standardized protocol (30,min baseline, 45,min RF or sham exposure, 10,min baseline), conducted in three ambient temperatures (Ta,=,24, 28, and 31°C). At each Ta, average PDs studied were 0, 27, and 35,mW/cm2 (Specific absorption rate (SAR),=,0, 5.94, and 7.7,W/kg). Mean data for each group showed minimal changes in core temperature and metabolic heat production for all test conditions and no reliable differences between CW and PW exposure. Local skin temperatures showed similar trends for CW and PW exposure that were PD-dependent; only the skin temperature of the upper back (facing the antenna) showed a reliably greater increase (P,=,.005) during PW exposure than during CW exposure. Local sweat rate and skin blood flow were both Ta - and PD-dependent and showed greater variability than other measures between CW and PW exposures; this variability was attributable primarily to the characteristics of the two subject groups. With one noted exception, no clear evidence for a differential response to CW and PW fields was found. Bioelectromagnetics 22:246,259, 2001. © 2001 Wiley-Liss, Inc. [source] Fluid shifts during cardiopulmonary bypass with special reference to the effects of hypothermiaBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 7 2000J. K. Heltne Background Generalized overhydration, oedema and organ dysfunction occurs in patients undergoing open heart surgery using cardiopulmonary bypass (CPB) and hypothermia. Inflammatory reactions induced by contact between blood and the foreign surfaces of the extracorporeal circuit are commonly held responsible for the disturbances in fluid balance (,capillary leak syndrome'). Using the CPB circuit reservoir as a fluid gauge (measuring continuous extracorporeal blood volume), fluid shifts between the intravascular and the extravascular space, and differences between normothermic and moderately hypothermic CPB, were examined. Methods Piglets were placed on CPB (thoracotomy) under general anaesthesia. In the normothermic group (n = 7) the core temperature was kept at 38°C before and during 2 h on CPB, whereas in the hypothermic group (n = 7) the temperature was lowered to 29°C during bypass. In addition to accurate recording of fluid during operation, the extracorporeal blood volume was kept constant by maintaining a certain blood level in the CPB circuit's reservoir. Acetated Ringer was used as priming solution in the CPB, as maintenance fluid and for adding fluid to the reservoir if necessary. Results Cardiac output, serum electrolytes and arterial blood gases were all similar in the two groups. Haematocrit fell significantly following the start of CPB in both groups. The reservoir fluid level fell markedly in both groups necessitating fluid supplementation. This extra fluid requirement was transient in the normothermic group, but persisted in hypothermic animals. At the end of 2 h of CPB the hypothermic animals had received seven times more extra fluid than the normothermic pigs. Conclusion There were strong indications of a greater fluid extravasation induced by hypothermia. The model described, using the PBC circuit reservoir as a fluid gauge, provides the opportunity for further study of fluid volume shifts, their causes and potential ways to manipulate fluid pathophysiology related to hypothermia and to PBC. © 2000 British Journal of Surgery Society Ltd [source] Exercise-induced hyperthermia in childhood: a case report and pilot studyACTA PAEDIATRICA, Issue 7 2009T Kallinich Abstract Hyperthermia is characterized by an increase of body core temperature due to exogenous heat exposure and/or endogenous heat production. Contrary to fever the hypothalamic-controlled temperature set point remains unchanged. Aim: To demonstrate that exercise-induced hyperthermia is a common phenomenon in childhood. Case: We describe a 5-year-old boy, who attended our outpatient clinic with a 6-month observation period of exercise-induced hyperthermia with rectal temperatures up to 39.0°C. Characteristically temperature dropped to normal values after cessation of exercise. Method: In eight children aged 5,8, tympanic and rectal temperatures were measured before and after exercise. Results: The rectal temperature increases frequently after exercise (p < 0.001), whereas tympanic temperature did not (p = 0.2). Conclusion:, Benign hyperthermia should be considered in children with increased body temperature of unknown sources. The site of temperature measurement might be critical in the identification of this condition. [source] Triadic bed-sharing and infant temperatureCHILD: CARE, HEALTH AND DEVELOPMENT, Issue 2002H. L. Ball Abstract The effects on infants of sleeping with their parents is currently the subject of much debate. One concern regarding infants who sleep in their parents' bed involves the possibility of overheating. Previous research reported a significantly greater core temperature of 0.1°C among a cohort of bed-sharing infants compared with a matched cohort of infants sleeping alone. This paper presents a preliminary analysis of the overnight rectal temperature of 12 of the 20 infants who were monitored sleeping alone and with their parents on separate nights at the University of Durham Parent-Infant Sleep Lab. No significant differences were found in all night rectal temperature, or temperature from 2 h after sleep onset between bed-sharing and cot sleeping nights. These preliminary analyses suggest a night-time difference in rectal temperature between routine bed-sharers and routine cot sleepers, however, these findings will be further explored in the full analyses for this study. [source] Successful treatment of profound hypothermia of the newbornACTA PAEDIATRICA, Issue 1 2009P Konopova Abstract We report a case of a profoundly hypothermic newborn with a core temperature of 25°C with a successful recovery and normal neurological outcome at 3 and 6 months. This term male infant had been exposed to a temperature of ,3°C for approximately 30 min. Slow re-warming, using external modalities was used in addition to volume expansion, heparinization, antibiotics and sedation. There is limited information available concerning the safest and most effective method of re-warming hypothermic newborns. Slow re-warming has been advocated as it replicates the normal physiological process in a neonate, which minimizes a negative therapy impact. Conclusion: The most significant decision regarding treatment is the identification of the most appropriate method and speed of re-warming. This report supports recommendations for gradual re-warming of a severely hypothermic newborn. Physiological cardiovascular mechanisms seemed to be intact during slow re-warming; this might be applicable to the treatment of profound hypothermia of the newborn. [source] Original article: Apparent thermal diffusivity estimation for the heat transfer modelling of pork loin under air/steam cooking treatmentsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 9 2010Massimiliano Rinaldi Summary Apparent thermal diffusivity linear functions vs. product temperature were estimated for pork cooked under two different treatments (forced convection, FC and forced convection/steam combined, FC/S) at 100, 110, 120 and 140 °C by means of experimental time,temperature data and a developed finite-difference algorithm. Slope and intercept of each function were employed to calculate apparent thermal diffusivity at 40, 55 and 70 °C. Generally, FC/S treatments gave significantly higher apparent thermal diffusivities in comparison with FC conditions. Apparent thermal diffusivities were used to develop a model for cooking time and final core temperature prediction on the basis of oven setting. The model was validated by means of additional cooking tests performed at different temperatures of those employed for model development. Root mean square error values lower than 3.8 °C were obtained comparing predicted and experimental temperature profiles. Percentage errors lower than 3.1% and 3.5% were, respectively, obtained for cooking times and final core temperatures. [source] The impact of mergers on relaxed X-ray clusters , III.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2008Effects on compact cool cores ABSTRACT We use the simulations presented in Poole et al. to examine the effects of mergers on the properties of cool cores in X-ray clusters. Motivated by recent Chandra and XMM,Newton observations, we propose a scheme for classifying the morphology of clusters based on their surface brightness and entropy profiles. Three dominant morphologies emerge: two hosting compact cores and central temperatures which are cool [CCC (compact cool core) systems] or warm [CWC (compact warm core) systems] and one hosting extended cores which are warm [EWC (extended warm core) systems]. In the cases we have studied, CCC states are disrupted only after direct collisions with merging cluster cores. This can happen in head-on collisions or during second pericentric passage in off-axis mergers. By the time they are relaxed, our remnant cores have generally been heated to warm core (CWC or EWC) states but subsequently recover CCC states by the end of the simulation. The only case resulting in a long-lived EWC state is a slightly off-axis 3:1 merger for which the majority of shock heating occurs during the accretion of a low-entropy stream formed from the disruption of the secondary's cool core. Since tdyn,tcool for all our relaxing merger remnant cores, compression prevents their core temperatures from falling until after they relax to the compact states allowed by their remnant central entropies. This naturally explains the population of relaxed CWC systems observed in recent Chandra and XMM,Newton observations with no need to invoke active galactic nuclei feedback. The morphological segregation in the Lx,Tx scaling relation noted by McCarthy et al. is qualitatively reflected in the results of our mergers as well. However, none of the cases we have studied produces systems with sufficiently high central entropies to account for the most underluminous EWC systems observed. Lastly, mergers do not efficiently mix the intracluster medium in our simulations. As a result, merging systems which initially host central metallicity gradients do not yield merger remnants with flat metallicity profiles. Taken together, these results suggest that once formed, compact core systems are remarkably stable against disruption from mergers. It remains to be demonstrated exactly how the sizable observed population of extended core systems was formed. [source] Soret Diffusion and Non-Ideal Dufour Conduction in Macroporous Catalysts with Exothermic Chemical Reaction at Large Intrapellet Damköhler NumbersTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2007Laurence A. Belfiore Abstract The adiabatic temperature rise in catalytic pellets is predicted from a modified version of the Prater equation. Onsager reciprocal relations for coupled heat and mass transfer are violated in an analysis of thermal diffusion in macroporous catalysts with exothermic chemical reaction when Dufour conduction (i.e., the diffusion-thermo effect) is neglected. In this contribution, Dufour conduction is analyzed for both ideal and non-ideal pseudo-binary gas mixtures that simulate the production of methanol from carbon monoxide and hydrogen. In the diffusion-controlled regime at large intrapellet Damköhler numbers where intermolecular collisions provide the dominant resistance to mass transfer within the catalytic pores, temperatures in the catalytic core could be much greater than predictions based on the original Prater equation when the Prater number exceeds 0.30. The molecular flux of thermal energy includes Fourier's law, the interdiffusional flux, and Dufour conduction. Diffusional mass flux includes Fick's law and the Soret effect. All physicochemical properties of the reactive gas mixture exhibit temperature dependence. There is essentially no difference between maximum intrapellet temperature predictions that include or neglect ideal Dufour conduction when external catalytic surface temperatures range from 300-400 K and thermal diffusion enhances the flux of "smaller" reactants toward the centre of the catalyst. For "large-molecule reactants" that participate in exothermic reactions, thermal diffusion opposes Fick's law and Dufour conduction opposes Fourier's law. Under these conditions, it is demonstrated that core temperatures are overestimated by neglecting both off-diagonal coupling mechanisms (i.e., Soret diffusion and Dufour conduction). Prater numbers greater than unity and unrealistically high gas pressures are required to distinguish between maximum intrapellet temperatures for ideal and real gas simulations, where the latter consider two-body interactions for Lennard-Jones molecules in the virial equation of state. On prédit l'augmentation de la température adiabatique dans les pastilles catalytiques à partir d'une version modifiée de l'équation de Prater. Les relations réciproques d'Onsager pour le transfert de chaleur et de matière couplé sont violées dans une analyse de la diffusion thermique dans les catalyseurs macroporeux avec réaction chimique exothermique lorsque la conduction de Dufour (p.ex., l'effet de thermo-diffusion) est négligée. Dans cet article, on analyse la conduction de Dufour pour des mélanges de gaz pseudo-binaires idéaux et non idéaux qui simulent la production de méthanol à partir d'oxyde de carbone et d'hydrogène. Dans le régime à diffusion contrôlée à grand nombre de Damköhler entre les pastilles pour lesquels les collisions entre les molécules fournit la résistance dominante au transfert de matière à l'intérieur des pores catalytiques, les températures dans le noyau catalytique pourraient être bien plus grandes que les prédictions basées sur l'équation de Prater originale lorsque le nombre de Prater excède 0,30. Le flux moléculaire de l'énergie thermique inclut la loi de Fourier, le flux interdiffusionnel, et la conduction de Dufour. Le flux massique diffusionnel inclut la loi de Fick et l'effet Soret. Toutes les propriétés physicochimiques du mélange de gaz réactif montre une dépendance thermique. Il n'y a essentiellement pas de différence entre les prédictions des températures maximales entre les pastilles qui incluent ou négligent la conduction de Dufour idéale quand les températures de surface catalytiques externes sont comprises entre 300 et 400 K; la diffusion thermique améliore le flux des réactifs «plus petits» vers le centre du catalyseur. Pour les «réactifs composés de grandes molécules» qui participent aux réactions exothermiques, la diffusion thermique s'oppose à la loi de Fick et la conduction de Dufour à la loi de Fourier. Dans ces conditions, il est démontré que les températures de noyau sont surestimées en négligeant les deux mécanismes de couplage hors-diagonales (c.à-d. la diffusion de Soret et la conduction de Dufour). Des nombres de Prater plus grands que l'unité et des pressions de gaz élevées peu réalistes sont nécessaires pour distinguer les températures maximales entre les pastilles entre les simulations de gaz idéales et réelles, en considérant pour ces dernières les interactions à deux corps pour les molécules de Lennard-Jones dans l'équation d'état du viriel. [source] | ||||||||||||||||||||||||||||