Dexamethasone decreases the incidence of shivering after cardiac surgery: a randomized, double-blind, placebo-controlled study

Shivering after cardiac surgery is common, and may be a result of intraoperative hypothermia. Another possible etiology is fever and chills secondary to activation of the inflammatory response and release of cytokines by cardiopulmonary bypass. Dexamethasone decreases the gradient between core and skin temperature and modifies the inflammatory response. The goal of this study was to determine whether dexamethasone can reduce the incidence of shivering. Two hundred thirty-six patients scheduled for elective coronary and/or valvular surgery were randomly assigned to receive either dexamethasone 0.6 mg/kg or placebo after the induction of anesthesia. All patients received standard monitoring and anesthetic management. After arrival in the intensive care unit (ICU), nurses unaware of the treatment groups recorded visible shivering, as well as skin and pulmonary artery temperatures. Analysis of shivering rates was performed by using chi2 tests and logistic regression analysis. Compared with placebo, dexamethasone decreased the incidence of shivering (33.0% vs 13.1%; P = 0.001). It was an independent predictor of reduced incidence of shivering and was also associated with a higher skin temperature on ICU admission and a lower central temperature in the early postoperative period. IMPLICATIONS: Dexamethasone is effective in decreasing the incidence of shivering. The effectiveness of dexamethasone is independent of temperature and duration of cardiopulmonary bypass. Shivering after cardiac surgery may be part of the febrile response that occurs after release of cytokines during cardiopulmonary bypass.     

Effects of skin surface temperature distribution of thermal manikin on clothing thermal insulation

Effects of the distribution of skin surface temperature were investigated on thermal insulation of clothing for whole and each body part. The experiments were carried out with a thermal manikin in a climatic chamber. The two types of clothing ensemble were measured. The measurement with nude thermal manikin were also conducted. The three variations of skin temperature distribution were set with the thermal manikin. The values of the thermal insulation of nude skin surface (Ia), the total thermal insulation of clothing (It) and the basic thermal insulation of clothing (Icl) were measured with this thermal manikin under each skin temperature distribution. As a result, the values of Ia and It were not affected by skin temperature distributions of the range of typical experimental conditions. However, It is necessary to carefully use the values of the thermal insulation of clothing for the body parts, because these values were more influenced by the skin temperature distribution than those for the whole body.     

Racemate and enantiomers of ketoprofen: phase diagram, thermodynamic studies, skin permeability, and use of chiral permeation enhancers

The role of intrinsic and extrinsic factors on transport of a chiral drug through the skin was studied. Ketoprofen (KP) was chosen as a model chiral drug. A possible relationship between the melting characteristics and the flux values of S- and RS-KP was investigated. The potential use of chiral enhancers, menthol and linalool, was also investigated. Thermal analyses were carried out for individual enantiomers and the racemate of KP. The melting temperature of each enantiomer was 22 degreesC lower than that of the racemic compound. Peak temperatures from the melting endotherms were plotted as a function of enantiomeric composition to give the binary phase diagram. The phase diagram suggested the presence of a racemic compound, and it was verified by calculations of the liquidus curve in the dystectic region using reported methods. Powder X-ray diffraction studies also confirmed that the racemate of KP is a racemic compound. The permeability of individual enantiomers and the racemate of KP through mice skin was determined in vitro using side-by-side diffusion cells. Transfer of R- and S-KP from aqueous solutions of both the racemate and pure enantiomer showed no significant differences in the rates of permeation, indicating that the rate of transfer of KP across the mice skin from these solutions was independent of the stereochemistry of the drug. No evidence of racemization during the transfer process was observed. The permeation-enhancing ratio of linalool was higher, but not significant, than that of l-menthol. The predicted ratio of enantiomer to racemate flux through the skin by the MTMT concept (1. 97) is in close agreement with the experimentally determined ratio (1.79) across mouse skin.     

Freezing temperature of finger skin

In 45 subjects, 154 frostnips of the finger were induced by cooling in air at -15 degrees C with various wind speeds. The mean supercooled skin temperature at which frostnip appeared was -9.4 degrees C. The mean skin temperature rise due to heat of fusion at ice crystallization was 5.3 degrees C. The skin temperature rose to what was termed the apparent freezing point. The relation of this point to the supercooled skin temperature was analyzed for the three wind speeds used. An apparent freezing point for a condition of no supercooling was calculated, estimating the highest temperature at which skin freezes at a given wind speed. The validity of the obtained differences in apparent freezing point was tested by an analysis of covariance. Although not statistically significant, the data suggest that the apparent freezing point with no supercooling decreases with increasing wind velocity. The highest calculated apparent freezing point at -15 degrees C and 6.8 m/s was 1.2 degrees C lower than the true freezing point for skin previously determined in brine, which is a statistically significant difference.     

Stability, controllability and observability of arterial circulation

Six subjects exercised on a bicycle ergometer at 60-70% of maximal aerobic power in a 25 degrees C ambient. Experiments on each subject were conducted at night (4:00-5:30 A.M.) and in daytime (noon-4:30 P.M.). Chest sweating rate (msw) was measured with resistance hygrometry. Forearm blood flow (BF), with an arm skin temperature of 35.5 +/- 1.2 degrees C (SD), was measured with electrocapacitance plethysmography. Esophageal temperature (Tes) was measured with a thermocouple at the level of the left atrium, and mean skin temperature (Tsk) was calculated from a weighted average of temperatures at three sites. Tes was corrected to a skin temperature of 33 degrees C as follows: T'es = Tes + (Tsk - 33 degrees C)/8. This correction reflects the relative contributions of Tes and Tsk to control of msw:T'es and BF:T'es relations were not consistently changed. In any given subject, thresholds for sweating and vasodilation were shifted about equally. These shifts averaged 0.57 degrees C (range: 0.23-0.93 degrees C)for msw and 0.63 degrees C (range: 0.17-0.98 degrees C) for BF.     

The effect of noradrenaline and 5-hydroxytryptamine injected into a lateral cerebral ventricle, on thermoregulation in the new-born lamb

1. Respiratory frequency, shivering, ear skin temperatures and rectal temperatures were observed following intraventricular injections of noradrenaline (NA), 5-hydroxytryptamine (5-HT) and saline (NaCl) into new-born lambs exposed to ambient temperatures of 4, 21, or 30 degrees C. 2. Intraventricular NA caused respiratory rate to decrease and body temperature to increase in the 30 degrees C environment. At 21 degrees C, it increased ear skin temperature but did not significantly affect rectal temperature. At 4 degrees C, NA decreased shivering and rectal temperature fell. 3. 5-HT elevated respiratory rate in the 30 degrees C environment and increased ear skin temperature in the 21 and 4 degrees C environments. In the 4 degrees C environment rectal temperature decreased. 4. In general, the change in rectal temperature was related to the dosage of drug administered. Control injections of NaCl had no significant effect on any of the variables measured. 5. The monoaminergic pathways involved in thermoregulation in the new-born lamb appear to be organized in a manner similar to that of the adult sheep and are functional at birth.     

Autonomic nervous system activity in autistic, schizophrenic, and normal men: Effects of stimulus significance.

Deficits in attention and cognition in autistic children have been attributed to problems in the early stages of stimulus processing and to autonomic dysregulation, but the evidence is conflicting. Our study addressed this problem by recording skin conductance, skin temperature, respiration rate, and heart rate (HR) during (a) a rest period, (b) a series of nonsignal tones, and (c) a simple warned reaction time (RT) task in autistic, schizophrenic, and normal men; we sought to remove extraneous sources of variance by testing only high-functioning autistic men (n?=?13); age?=?18–39). Control subjects were age-matched normal men (n?=?19) and schizophrenic men (n?=?13) not chronically hospitalized. Autistic men had higher respiration rates, lower skin temperature, and higher HR variability at rest than controls. They were not different on other arousal measures or generally in responding to nonsignal tones but had severely impaired tonic and phasic autonomic responses and motor responses in the RT task. Schizophrenic subjects were also impaired but significantly less so in some aspects of responding. The results do not suggest problems in stimulus processing, but there is evidence of autonomic dysregulation and a pronounced inability to mobilize processing resources appropriately, perhaps a common problem with schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Calculation of mean skin temperature and changes in body heat content during paediatric anaesthesia

Mean skin temperature and changes in body heat content were calculated in several different ways from measurements made in five children during operation. Mean skin temperatures were calculated from 162 sets of measurements using 15, 12, eight, seven and four skin sites with various formulae modified according to age. The results of other formulae were compared with age-adjusted, area-weighted 15-site mean skin temperature which was used as a reference. Changes in body heat content were calculated from Burton's equation in different ways and errors from different variables in the formula were evaluated. Mean skin temperature from 12 skin sites was within 0.5 degrees C of the 15-point reference method, and that from four sites within 1 degree C. The core temperature selected and the weighting coefficients used in calculating mean body temperature were more important sources of error in the determination of change in body heat content than was mean skin temperature.     

Characterization of the foot withdrawal response to noxious radiant heat in the rat

The rat foot withdrawal response to noxious radiant heat has been used as a model of nociception that is particularly useful for measurements of unilateral changes in nociceptive responses. The purpose of these studies was to characterize the foot withdrawal response to graded rates of noxious skin heating. Response latencies and both surface and subsurface temperatures produced by 6 different intensities of radiant heat were measured to determine whether response latency is an appropriate measure of nociceptive threshold. With constant intensity heating, the temperature of the skin surface increased as logarithmic function of time, while subsurface temperature increased linearly with time. In contrast, a heating function that linearly increased the temperature at the skin surface increased the subsurface temperature as an exponential function of time. These results and published reports of nociceptive afferent recordings which used similar skin heating parameters, indicate that nociceptive foot withdrawal responses occur at about the same skin temperature as the activation of nociceptors. These results also indicate that since constant intensity heating produces linear increases in the subsurface temperature, then response latency can be used as an accurate measure of changes in nociceptive threshold produced by drug treatments. These observations lead to the conclusion that the foot withdrawal response latency is a valid and useful measure of nociceptive threshold in rodents.     

Methodological studies of the estimation of loss of sodium, potassium,calcium and magnesium through the skin during a 10 km run

An estimation of the electrolytic losses through the skin was evaluated in a run over a distance of 10 km on a 400 m Tartan-trac. Na, K, Ca, and Mg excreted by the skin were collected in standardised clothing and thereafter washed out. The remaining electrolytes on the skin were collected by washing the body with deionized water. In addition, the concentrations of hormones and metabolites in blood before and after the race were ascertained. Mean ambiant temperature and relative humidity amounted to 21 degrees C and 35%, respectively. The mean performance was 40.5 min. and the average body weight loss was 1.45 kg. The only significant changes in the serum concentrations were the increases of free fatty acids and glycerol. This can be explained, together with a slight increase of glucose and a decrease of insulin, by a higher sympathoadrenergic activity. In the mean 20 mg calcium, 5 mg magnesium, 200 mg potassium, and 800 mg sodium were lost by the skin per kg body weight loss. Those amounts compared well with corresponding data found in literature. The described method can be proposed for further experiments.     

Punctate pressure sensitivity: effects of skin temperature

The dependence on skin temperature of tactile sensitivity to punctiform (hair) stimulation of the finger tip came under study in five subjects. Their data show that punctate sensitivity is relatively stable over a wide range of thermal environments. On the average, some elevation of touch threshold occurred at a skin temperature of 20 degrees C (i.e., about 10 degree below normal), but severe loss of sensitivity first occurred at 10 degrees C. A small but possibly insignificant loss appeared at skin temperatures of 40 and 43 degrees C. The relatively stable behavior of the punctate threshold between about 20 and 40 degrees C contrasts with that of the vibrotactile threshold, which, at least for high frequencies, depends strongly on the skin temperature.     

Physiological and psychological effects of head heating during rest and work

The purpose of this study is to obtain some knowledge related to physiological and psychological effects of head heating by radiation on the vital body under varying conditions of the environmental temperature and physical activity. The study was proceeded with experiments 1 and 2 using 8 women, all in good health as subjects. In experiment 1, firstly the subject at rest was kept at an ambient temperature of 28 degrees C for 40 minutes. The, moving to a room kept at an ambient temperature of 18 degrees C or 28 degrees C, the state at rest was maintained with head heating at 3 radiant intensities (without radiation, 35 degrees C and 40 degrees C of globe temperature) for a further 40 minutes. In experiment 2, continued from the same procedure of experiment 1, work on the ergometer was performed for 30 minutes with head heating at 2 radiant intensities (without radiation and 35 degrees C of globe temperature). Items measured were tympanic temperature, skin temperatures, heart rate, and subjective sensations. The principal results obtained are as follows: 1) Tympanic temperature, forehead skin temperature and score of thermal sensation of head increased, while the others decreased at 18 degrees C. 2) Decrease of scores was inhibited by head heating in finger skin temperature, toe skin temperature and heart rate. 3) When radiant intensities at 35 degrees C and 40 degrees C were compared, statistical significant difference was noted in forehead skin temperature only, the difference of radiant conditions gives a little effect to the vital body. 4) Effects brought by head heating during rest decreased owing to the addition of work.     

Striatal dopamine dynamics are altered following an intranigral infusion of iron in adult rats

Exercise has a noted effect on skin blood flow and temperature. We aimed to characterize the normal skin temperature response to exercise by thermographic imaging. A study was conducted on ten healthy and active subjects (age=25.8+/-0.7 years) who were exposed to graded exercise for determination of maximal oxygen consumption (VO2 max), and subsequently to constant loads corresponding to 50%, 70%, and 90% of VO2 max. The skin temperature response during 20 min of constant load exercise is characterized by an initial descending limb, an ascending limb and a quasi-steady-state period. For 50% VO2 max, the temperature decrease rate was - 0.0075+/-0.001 degrees C/s during a time interval of 390+/-47 s and the temperature increase rate was 0.0055+/-0.0031 degrees C/s during a time interval of 484+/-99 s. The level of load did not influence the temperature decrease and increase rates. In contrast, during graded load exercise, a continuous temperature decrease of -0.0049+/-0.0032 degrees C/s was observed throughout the test. In summary, the thermographic skin response to exercise is characterized by a specific pattern which reflects the dynamic balance between hemodynamic and thermoregulatory processes.     

Prediction of equivalent environments by energy exchange and assessments of physiological strain and discomfort

The described equivalence postulate was confirmed experimentally by examining physiological responses as well as discomfort sensation in a series of predicted equivalent conditions during exercise (congruent to 3 met). ET or the equivalent Ta at 50% RH is a single independent variable that is uniquely related to the mean skin temperature (Tsk), skin wettedness (w), body core temperature (Tcore) and sense of discomfort.     

电渣连铸锭表面质量的影响因素

渣皮的厚度、均匀性和力学性能是影响抽锭电渣钢锭表面质量的主要因素。薄而均匀渣皮是获得良好连铸锭表面质量的关键。文中分析了渣池电流密度分布、结晶器壁附近的热传导条件、渣成分和"高温区"温度变化等因素对渣皮厚度的影响。生产试验表明,通过控制操作温度和渣系成分获得薄而均匀的渣皮,并确保渣系具备长渣形式和适当的高温强度及塑性可得到良好表面质量的电渣连铸锭。     

Effects of local restriction of evaporation and moderate local ventilation on thermoregulatory responses in exercising humans

Ten healthy young men participated in two series of three trials: series 1 (C1) with, or without, local restriction of evaporation (either on the trunk or on the legs) and series 2 (C2) with, or without, local moderate nitrogen ventilation (40 l.min-1) under an impermeable garment (trunk or leg ventilation). After 60-min rest in a thermoneutral environment, the subjects exercised in a warm environment [30 degrees C, 47% relative humidity (rh) during C1 and 29% rh during C2] on a cycle ergometer for 60 min at 70 W during C1 or at 60 W during C2. During C1, local covering with plastic foil did not increase internal temperature, but increased the mean skin temperature with a higher effect in the case of leg restriction. The trunk skin temperature was affected by the leg covering while the leg skin temperature was not changed by the trunk covering. Only the local sweat rate of the trunk was increased by the two restriction conditions. During C2, internal temperature was decreased by local ventilation while mean skin temperature was reduced only by trunk ventilation. The local ventilation affected only trunk skin temperature with a greater decrease during trunk ventilation. Trunk ventilation did not influence the skin temperature of the legs while ventilation of the legs decreased trunk skin temperature. In addition, leg ventilation decreased the sweat rate of the legs. The impermeable suit worn during C2 led to a greater physiological strain compared to the plastic film worn during C1 even with local ventilation under the impermeable garment. As expected, limiting sweat evaporation led to an increase in physiological strain. Microclimate ventilation at a rate of 40 l.min-1 was not sufficient to allow total heat dissipation but allowed 60-min exercise in a warm environment to be completed without excessive heat accumulation. It would appear that ventilation of the trunk locally was the best solution because of the smaller increase in skin temperature and higher sweating capacity of the trunk.     

Individual differences and autonomic control: Absorption, hypnotic susceptibility, and the unilateral control of skin temperature.

Proposed to (a) replicate earlier findings that human Ss could voluntarily control peripheral skin temperature, (b) test the hypothesis that hypnotic susceptibility and the capacity for absorbed, imaginative attention would enhance autonomic learning and performance, and (c) demonstrate a learning effect, if one exists. A comparison was made with 7 Ss who scored high and 7 Ss who scored low on both a modified version of the Harvard Group Scale of Hypnotic Susceptibility and the Tellegen Absorption Scale. Auditory feedback was used to train Ss to produce a difference in skin temperature in one hand relative to the other in a direction specified by the E. Large and reliable performance and learning effects were found, but they were unrelated to hypnotic susceptibility or the capacity for absorbed, imaginative attention. Variables that might account for individual differences in learning and performance are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of skin temperature on multifrequency bioelectrical impedance analysis

This study assessed the effects of changes in skin temperature on multifrequency bioimpedance analysis (MF-BIA) and on the prediction of body water compartments. Skin temperature (baseline 29.3 +/- 2.1 degrees C) of six healthy adults was raised over 50 min to 35.8 +/- 0.6 degrees C, followed by cooling for 20 min to 26.9 +/- 1.3 degrees C, by using an external heating and cooling blanket. MF-BIA was measured at both distal (conventional) and proximal electrode placements. Both distal and proximal impedance varied inversely with a change in skin temperature across all frequencies (5-500 kHz). The change in proximal impedance per degree centigrade change in skin surface temperature was approximately 60% of distal impedance. The change in measured impedance at 50 kHz erroneously increased predicted total body water (TBW) by 2.6 +/- 0.9 liters (P < 0.001) and underpredicted fat mass by 3.3 +/- 1.3 kg (P < 0.0001). Computer modeling of the MF-BIA data indicated changes in predicted water compartments with temperature modifications; however, the ratio of extracellular water (ECW) to TBW did not significantly change (P < 0.4). This change in impedance was not due to a change in the movement of water of the ECW compartment and thus probably represents a change in cutaneous impedance of the skin. Controlled ambient and skin temperatures should be included in the standardization of BIA measurements. The error in predicted TBW is < 1% within an ambient temperature range of 22.3 to 27.7 degrees C (72.1-81.9 degrees F).     

Correlation study on infrared thermography and nerve root signs in lumbar intervertebral disk herniation patient: a short report

OBJECTIVE: To determine whether infrared skin thermography is an objective measurement reflecting the seriousness of nerve root irritation in lumbar disk herniation patients. DESIGN: Quantified nerve root signs by physical examination were collected from the patients along with the infrared skin temperature measurement on the lumbosacral region and posterior part of thighs. A correlation study was applied to observe the relation between the nerve root signs and the skin temperature before a successful conservative treatment (mainly spine manipulation), and between the alteration of nerve root signs and that of skin temperature after the treatment. SETTING: Hospitalized care. PATIENTS: Twenty-seven hospitalized samples with computed tomography or magnetic resonance approval were consecutively selected during the latter half of 1990. MAIN OUTCOME MEASURE: Changes in nerve root signs. RESULTS: The temperature difference between a troubled thigh and healthy one is significantly correlated to the score of the nerve root signs before the treatment; and the reduction of temperature difference between two thighs is also significantly correlated with decreasing score of nerve root signs after the treatment. The correlation between the temperature difference on the left and right sides of the lumbosacral region and the nerve root signs before the treatment is insignificant; and the variation of the temperature difference of the same region after the treatment is not correlated with the decreasing score of the nerve root signs. CONCLUSION: Infrared skin thermography of lower extremities might be an objective sign in signaling the soothing process of the nerve root irritation in lumbar disk herniation patients, which may help a doctor in checking the responses of the patient to treatment.     

Influence of localized auxiliary heating on hand comfort during cold exposure

There is a need for a hand-heating system that will keep the hands warm during cold exposure without hampering finger dexterity. The purpose of this study was to examine the effects of torso heating on the vasodilative responses and comfort levels of cooled extremities during a 3-h exposure to -15 degreesC air. Subjects were insulated, but their upper extremities were left exposed to the cold ambient air. The effect of heating the torso [torso-heating test (THT)] on hand comfort was compared with a control condition in which no torso heating was applied, but Arctic mitts were worn [control test (CT)]. The results indicate that mean finger temperature, mean finger blood flow, mean toe temperature, mean body skin temperature, body thermal comfort, mean finger thermal comfort, and rate of body heat storage were all significantly (P < 0.05) higher on average (n = 6) during THT. Mean body heat flow was significantly (P < 0.05) lower during THT. There were no significant differences (P >/= 0.05) in rectal temperature between CT and THT. Mean unheated body skin temperature and mean unheated body heat flow (both of which did not include the torso area in the calculation of mean body skin temperature and mean body heat flow) were also calculated. There were no significant differences (P >/= 0.05) in mean unheated body skin temperature and mean unheated body heat flow between CT and THT. It is concluded that the application of heat to the torso can maintain finger and toe comfort for an extended period of time during cold exposure.