Higher Skin Temperature Research Articles

Sweat Response During Submaximal Aerobic Exercise in Persons With Multiple Sclerosis

ABSTRACT The relationship between the metabolic, thermal load of exercise, sudomotor (sweat) response, and core temperature was examined in 20 individuals with multiple sclerosis (MS) and eight non-MS control subjects. Participants performed an incremental bicycle test of maximal aerobic power (VO2peak) fiom which 50% of VO2peak was calculated. A 50% VO2peak endurance test was performed while subject wore a full-body water garment. Initial circulating water temperature of 27°C was increased 2°C every three minutes to enhance the thermal load. Core, skin, and circulating water temperatures were monitored. Onset of sweating was measured at five sites. Results showed that 50% of the subjects with MS had an abnormally low sweat response in spite of relatively high skin temperatures (> 35°C) at several sites. The thermal load (kJ/kg) of these subjects at test termination was 89% higher than that of the MS subjects with a normal sweat response. Clinicians should be aware that sweat response may be blunted or absent in many patients with MS. Guidance for ways to enhance heat dissipation under adverse climatic conditions or during activities that increase whole body metabolism should be provided to patients with MS. Perhaps of even greater importance was the finding that increased core and skin temperature during exercise did not result in the appearance of any MS-related symptom in 95% of our sample. This finding is in direct conflict with much of the clinical literature. (Int J MS Care. 2001; 3(4): 26–33.)

Antibiotic Prophylaxis in Clean Surgery: Clean Non-Implant Wounds

Wound infection after clean surgery (the majority being hernia, varicose vein and breast surgery) is often greatly underestimated. If a trained and blinded observer is involved using close and prolonged surveillance to at least 30 days postoperatively with appropriate definitions or wound scores, an infection rate of up to 15% or more may be found. Equally controversial is the value of prophylactic antibiotics in preventing postoperative wound infection; there is no clear cut evidence of efficacy and some random controlled trials (RCTs) have shown no differences at all. There is a need for guidelines to be drawn up but further RCTs may be needed.An alternative to antibiotics is the systemic warming of patients or the local warming of the operative site prior to surgery. In day case surgery in particular, patients may have been deprived of fluids for 12h prior to surgery; they may become cold whilst waiting for surgery dressed in a theatre gown; and their apprehension may not be controlled with anxiolytics. The inflammatory response may be obtunded with an increased risk of superadded infection or poor healing in cutaneous tissue resulting in wound separation and fat necrosis. Only a third of sampled purulent discharges grow skin organisms such as Staphylococcus aureus or epidermidis.In a study of 421 patients the 138 randomly assigned to local warming (Warm Up, Augustine Medical) had a wound infection rate of 3.6% compared with another group of 139 randomly assigned to systemic warming (Bair Hugger, Augustine Medical) of 5.8%. A standard-treated third group of 139 had a wound infection rate of 13.7% (P<0.001). The warmed patients also had significantly lower wound scores based on 4 systems, had higher skin temperatures and capillary flow prior to surgery and were prescribed fewer postoperative antibiotics by their family doctors in the 6 postoperative weeks (15.9% vs 6.5%; P=0.002).Wound infections are more common than generally accepted if they are looked for by close surveillance. Antibiotics may be avoided by the use of warming with the lessening of the risks of allergy, resistance and emergence. It is uncertain whether antibiotic prophylaxis has a role in clean wound surgery. Breast surgery carries the highest risk of wound infection and this may risk delay in receiving planned adjuvant chemotherapy or radiotherapy. Perioperative warming of the operative site may be of greatest value in this group of patients.

Mitigation of Fouling in Bitumen Furnaces by Pigging

Processing of Athabasca oil sands bitumen requires preheating of the feed to temperatures in the range of 350−500 °C. At these temperatures significant amounts of solid foulant can be deposited on the walls of the furnaces. Ultimately, buildup of the deposit causes premature shutdown of the process, either because of excessively high tube skin temperatures or because of high pressure drop across the furnace. Steam/air de-coking, which has been practiced in the past, is unable to eliminate all the deposit since the foulant contains significant quantities of non-carbonaceous material. Currently, the preferred method to address this problem is pigging assisted by high-pressure water. The feed to the furnaces typically contains close to 0.5 wt % inorganic solids originating from the mineral matrix from which the bitumen is extracted. Elemental analysis of the feed identifies 300−450 ppm iron, much of which can be attributed to the components of the inorganic matrix, such as pyrite, iron carbonate, and iron-bearing clays. However, it is expected that soluble organic iron species, such as naphthenates and carboxylates, are more likely to decompose at the temperatures in the furnaces and to convert to iron sulfide and deposit within the furnace. Samples of foulant were collected from two furnace pigging operations, one at the Suncor Energy Inc. coker furnace and one at the Syncrude Canada Ltd. LC Finer furnace. The samples were taken at timed intervals that allowed a profile of the foulant within the cross-section of the furnace tube to be completed. After washing and drying, the foulant samples were analyzed for carbon, sulfur, and a variety of metals and inspected by optical petrography. Coker furnace foulants exhibited high concentrations of both carbonaceous material and iron sulfide. The iron sulfide concentration was highest at the wall and declined as the distance from the wall increased. The carbon content showed the reverse trend, suggesting that coke formation became the more important factor as the deposition process proceeded. This reverse trend coincided with the increase in tube skin temperature. Fluid and skin temperatures are much lower in the LC Finer furnace than in the coker furnace; therefore, the tendency to coke formation is reduced. As a result, the composition of the foulant from the LC Finer furnace was more constant and consisted almost entirely of iron sulfide. It was estimated that the amount of iron deposited as foulant corresponded to about 0.05 wt % of the total iron in the feed that passed through these furnaces.

A New Approach to an Accurate Wind Chill Factor

Abstract Winter weather often shows a severity marked by low dry-bulb temperature combined with high wind speed. The wind chill factor is now a standard meteorological term to express this severity. This factor, or more appropriately the wind chill temperature, represents that air temperature without wind that would effect the same heat loss rate from bare human skin as that due to the actual combined dry-bulb temperature and wind. Currently used wind chill factors derive from a study conducted by the U.S. Antarctic Service over 50 years ago. The data then collected was used to develop a cooling rate as a function of wind speed, which in turn was used to formulate an equation still in use today. The equation is based on primitive experiments with a container of freezing water and an unrealistically high human skin temperature. A more appropriate estimate of the thermal properties of the skin and implementation of modern heat transfer theory can provide a more realistic wind chill factor. Recent research s...

Perfusion of the human finger during cold-induced vasodilatation.

We have investigated the effect of severe local cooling on the vasomotor activity of the arteriovenous anastomoses (AVAs) and other finger vessels. The right third finger was subjected to local cooling (3 degrees C) for 30-45 min in 21 healthy, thermoneutral subjects. Blood velocity in the third finger arteries of both hands was simultaneously recorded using ultrasound Doppler, and skin temperature and laser-Doppler flux from the pulp of the cooled finger were also recorded. The results demonstrate that the initial cold-induced vasoconstriction during severe local cooling involves constriction of the AVAs as well as the two main arteries supplying this finger. During cold-induced vasodilatation (CIVD), the maximum velocity values were not significantly different from those before cooling. Furthermore, the velocity fluctuations in the cooled finger were in most subjects found to be synchronous with the velocity fluctuations in the control finger. This indicates that the large blood flow to the finger and the high skin temperature during CIVD are caused by relaxation of the smooth muscle cells of the AVAs.

Preharvest exposure to the sun influences postharvest responses of ‘Hass’ avocado fruit

‘Hass’ avocados (Persea americana Mill.) exposed to direct sunlight (sun fruit) had diurnal temperature cycles with flesh tissue reaching as high as 43°C under ambient temperatures of 15–25°C. The response of sun and shaded fruit to postharvest treatments differed significantly. External damage from hot water treatments of 50°C for up to 10 min, was lower in sun fruit, particularly on the exposed side of the fruit. Similarly, while shaded fruit had high levels of external chilling injury when stored at 0.5°C for up to 28 days, the exposed side of the fruit was undamaged. Leakage of electrolytes from skin tissue from the exposed side of sun fruit did not increase during storage, while that from shaded fruit increased by about 60%. In addition, for fruit ripened without storage, sun fruit took longer to ripen than shade fruit. Changes in heat shock protein (hsp) gene expression and specific protein bands reflected the diurnal temperature cycle, with up-regulation of hsp mRNA and synthesis of specific proteins at flesh temperatures >30°C. Thus, exposure of fruit to the sun results in high skin and flesh temperatures, and consequently reduced incidence of postharvest heat and chilling injuries. These beneficial effects are similar to those found following postharvest heat treatments.

Dexamethasone Decreases the Incidence of Shivering After Cardiac Surgery

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 chi squared 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. (Anesth Analg 1998;87:795-9)

Metabolic and hormonal changes during the molt of captive gray seals (Halichoerus grypus).

Body mass, resting metabolic rates (RMRs), and serum thyroid hormones concentrations of six captive gray seals (Halichoerus grypus) were measured at regular intervals before, during, and after the annual molt. Changes in body mass suggested that the animals had increased energy expenditures during the last stage of the molt. These were associated with significantly elevated RMRs during the molt, the increase being more pronounced in juveniles ( < or = 53%) than in adults ( < or = 17%). The increase in RMR probably reflects the cost of generating a new pelt or to sustain a high skin temperature. Serum total and free thyroxine concentrations were elevated for all animals during the molt, but only juveniles had elevated serum triiodothyronine concentration. The increase in thyroid hormones occurred only during the last stage of the molt, suggesting that the role of thyroid hormones during the molt may be to sustain rapid hair growth in the last stage of molt or to maintain elevated heat production, rather than to initiate hair growth.

A standard test of heat-pain responses using CASE IV

Heat-pain threshold and stimulus response characteristics can be evaluated with graduated heating pulses from a radiant heat source or a contact thermode. Results may be used to: (1) evaluate differences in sensation among anatomical sites, sides of the body, and with development and aging; and (2) provide an end-point for the study of the efficacy of drugs; or to follow the course of sensory alteration in disease (medical practice, epidemiologic studies, and controlled clinical trials). Because there is great variability in how tests of this kind are performed and scored, comparisons of results among medical centers are difficult. To meet this need, we have developed, and here describe, a standardized and validated test of heat-pain. We use both pyramidal and trapezoid-shaped stimuli. The range of stimulus magnitudes we recommend is sufficient to test heat-pain at a sensitive region (the face) of young people and an insensitive region (the foot) of healthy old people. From tests on healthy subjects and patients, we find that neither our previously published forced-choice or 4, 2, and 1 stepping algorithms are suitable for testing heat-pain sensation. We, therefore, introduce the Non-Repeating Ascending with Null Stimuli (NRA-NS) algorithm which performs satisfactorily. The graphed data points of responses to increasingly stronger heat pulses were made up of two components-the no pain (0) response line and the heat-pain response line (≥1 numerical scaling of the pain responses graded from 1 [least] to 10 [greatest]). For the pain responses, we found that usually a curve could be fit using a quadratic equation. Using this equation, or interpolation where necessary, it is possible to compute the heat-pain detection threshold (HPDT or HP:0.5), an intermediate heat-pain response (HP:5.0), and the difference between the two (HP:5.0 − 0.5). Our studies show that a certain time is needed between successive stimuli and tests to minimize changing basal skin temperature or threshold. We also demonstrated that low or high baseline skin temperatures can affect heat-pain responses, therefore, we advocate specific testing conditions. Based on a study of 25 healthy subjects, the reproducibility of the test falls within ±1 stimulus steps 88% of the time for HP:5.0 and 76% of the time for HP:0.5. The precise approaches employed to make the test standard and reproducible are described. We illustrate that the algorithm and testing system is able to document altered pain threshold with skin abrasion, with intradermal injection of nerve growth factor, and with diabetic polyneuropathy.

Physiological and perceptual responses to forearm immersion in cold water

Endeavours to determine the physiological and perceptual responses to forearm cold water immersion as influenced by the use of an experimental fireproof carbonaceous insulation (ECI), Thinsulate (a commercial insulation), and Nomex flight gloves. The primary objective was to determine if ECI could provide adequate protection from cold water immersion while providing superior protection from fire. Physiological responses including rectal and skin temperatures to –1 degree C water were recorded. Perceptions of thermal discomfort and grip strength were also measured. The experimental carbonaceous insulation was able to provide better thermal protection as evidenced by significantly higher skin temperatures than the Thinsulate. Subjects perceived the Thinsulate gloves to be only slightly more comfortable than the ECI gloves. Both ECI and Thinsulate provided negligible loss of grip strength. The Nomex gloves provided virtually no thermal protection and substantial loss of grip strength post‐immersion.

Effects of music on physiological and affective responses to graded treadmill exercise in trained and untrained runners

The influence of music on physiological and affective exercise responses was studied in 8 trained and 8 untrained runners under three music conditions (“no”, “sedative”, and “fast”) during low, moderate, and high intensity exercise. Repeated measures ANOVA revealed increased respiratory frequency (F R) during fast music as compared to the no music and sedative music conditions ( p < 0.01). Plasma cortisol levels did not differ at baseline across the music conditions; however, following high intensity exercise, higher cortisol levels were associated with fast music as compared to no music and sedative music (music × intensity interaction, p < 0.01). Affective measures during exercise (FEELING scale) showed no overall training group differences; however, there was a music × group × intensity interaction ( p < 0.05) in which untrained subjects reported more positive affect compared to trained subjects while listening to fast music during low and high intensity exercise. Data collected at voluntary exhaustion revealed significantly more positive affect and higher skin temperature ( p values < 0.01) in untrained compared to trained subjects. Collectively, these results suggest listening to fast, upbeat music during exercise may be beneficial for untrained runners but counterproductive for trained runners.

Influences of Foliage Plants on Human Stress during Thermal Biofeedback Training

Twelve 20-minute thermal biofeedback sessions were conducted with 26 university students. Visual stimuli were provided by a living foliage plant, a life-sized color photograph of that plant, or a metal stool (control). Of the participants, 38% responded positively to the presence of a live plant or plant photograph, while 23% showed lower stress in the control room. Stress reduction, as indicated by higher skin temperatures, occurred within the first 5 to 8 minutes of a 20-minute thermal-biofeedback session. A nonplant visual stimulus was not part of the experiment. The results are not intended as comparative, nor do they attribute unique or superior effects to plants. Due to the small number of participants, no significant results were obtained, but the trends were important and are being reported to help further research in this area.

Intrathecal phentolamine increases blood flow and skin temperature in the hind limbs of dogs.

Spinal anesthesia with local anesthetics increases blood flow and skin temperature in the lower extremities. Although the effect of α2 adrenoceptor agonists on the spinal cord has been confirmed, there has been no such report of the effects of α-adrenoceptor antagonists. We studied the effects of intrathecal administration of phentolamine on the blood flow in the femoral artery and skin temperature in the hind limbs of seven dogs. One ml of 3% lidocaine (L group) or 1 ml of 0.1% phentolamine (P group) was injected into the intrathecal space. Blood flow significantly increased at 3 min in both groups, and no significant difference was observed between the groups at any phase. Pad skin temperature in the hind limbs increased significantly at 5 min in the L group and at 3 min in the P group (P<0.05). The only significant difference was observed at 30 min. High pad skin temperature continued for 60 min in the L group and for 90 min in the P group. With phentolamine i.v. (1 mg), there were no changes in blood flow in the femoral artery or pad skin temperature; there was only a decrease in blood pressure. In conclusion, the intrathecal α-adrenoceptor antagonist, phentolamine, increases blood flow in the femoral artery and pad skin temperature in hind limbs in dogs similar to lidocaine.

Effect of insulin concentration, subcutaneous fat thickness and skin temperature on subcutaneous insulin absorption in healthy subjects.

Subcutaneous insulin absorption kinetics were assessed in 50 healthy study subjects (21 female, 29 male; age 26 +/- 3 years, BMI 22.5 +/- 1.8 kg/m2; mean +/- SD) during 45 min after periumbilical injection of soluble human U40- or U100-insulin (0.15 IU/kg). Subcutaneous fat thickness was measured by ultrasound, and skin temperature at the injection site was registered. Serum insulin concentrations increased within 30 min from basal values of 37 +/- 15 to 140 +/- 46 pmol/l after U40-insulin and from 36 +/- 10 to 116 +/- 37 pmol/l after U100-insulin (p < 0.001). After 45 min serum insulin concentrations were 164 +/- 43 pmol/l with U40-insulin and 128 +/- 35 pmol/l with U100-insulin (p < 0.001). Decline in blood glucose levels and suppression of C-peptide were comparable. The serum insulin levels reached 30 and 45 min after U40- and U100-insulin injection were positively correlated with skin temperature (p < 0.0008), and negatively correlated with subcutaneous fat thickness (p < 0.009). In conclusion, the lower insulin concentration of U40-insulin, higher skin temperature, and a thinner subcutaneous fat tissue at the injection site are associated with accelerated and enhanced subcutaneous insulin absorption.

The effect of evaporative cooling of respiratory protective devices on skin temperature, thermal sensation, and comfort.

High skin temperature of the face is a major source of discomfort while wearing respiratory protective devices. In this paper theoretical considerations of thermal exchange between the face and the environment with and without a mask are discussed to elucidate factors that may improve the design of masks to increase their acceptability. Comfort thresholds have been related to skin temperature for both resting and exercising subjects. Skin temperature below 34.5 degrees C at rest, and 31 degrees C during exercise, is rated as comfortable. In a previous study it was determined that evaporative cooling could reduce skin temperature and decrease discomfort in a dummy mask. In the present study evaporative cooling of a more sophisticated dummy mask and a modified Scott model 66 twin-cartridge respirator was tested in resting and exercising subjects. Skin temperature was significantly reduced when wet felt covered the surface of both masks and at rest the masks were rated as significantly more comfortable than with dry felt on the outer surface. It is concluded that evaporative cooling of an existing face mask can reduce skin temperature to the comfort threshold in resting subjects. Data suggest that similar results are attainable for exercising subjects.

The Effect of Evaporative Cooling of Respiratory Protective Devices on Skin Temperature, Thermal Sensation, and Comfort

High skin temperature of the face is a major source of discomfort while wearing respiratory protective devices. In this paper theoretical considerations of thermal exchange between the face and the environment with and without a mask are discussed to elucidate factors that may improve the design of masks to increase their acceptability. Comfort thresholds have been related to skin temperature for both resting and exercising subjects. Skin temperature below 34.5°C at rest, and 31°C during exercise, is rated as comfortable. In a previous study it was determined that evaporative cooling could reduce skin temperature and decrease discomfort in a dummy mask. In the present study evaporative cooling of a more sophisticated dummy mask and a modified Scott model 66 twin-cartridge respirator was tested in resting and exercising subjects. Skin temperature was significantly reduced when wet felt covered the surface of both masks and at rest the masks were rated as significantly more comfortable than with dry felt on the outer surface. It is concluded that evaporative cooling of an existing face mask can reduce skin temperature to the comfort threshold in resting subjects. Data suggest that similar results are attainable for exercising subjects.

Human tolerance to heat strain during exercise: influence of hydration.

This study determined whether 1) exhaustion from heat strain occurs at the same body temperatures during exercise in the heat when subjects are euhydrated as when they are hypohydrated, 2) aerobic fitness influences the body temperature at which exhaustion from heat strain occurs, and 3) curves could be developed to estimate exhaustion rates at a given level of physiological strain. Seventeen heat-acclimated men [maximal oxygen uptake (VO2max) from 45 to 65 ml.kg-1.min-1] attempted two heat stress tests (HSTs): one when euhydrated and one when hypohydrated by 8% of total body water. The HSTs consisted of 180 min of rest and treadmill walking (45% VO2max) in a hot-dry (ambient temperature 49 degrees C, relative humidity 20%) environment. The required evaporative cooling (Ereq) exceeded the maximal evaporative cooling capacity of the environment (Emax); thus thermal equilibrium could not be achieved and 27 of 34 HSTs ended by exhaustion from heat strain. Our findings concerning exhaustion from heat strain are 1) hypohydration reduced the core temperature that could be tolerated; 2) aerobic fitness, per se, did not influence the magnitude of heat strain that could be tolerated; 3) curves can be developed to estimate exhaustion rates for a given level of physiological strain; and 4) exhaustion was rarely associated with a core temperature up to 38 degrees C, and it always occurred before a temperature of 40 degrees C was achieved. These findings are applicable to heat-acclimated individuals performing moderate-intensity exercise under conditions where Ereq approximates or exceeds Emax and who have high skin temperatures.

Clinical evaluation of thermography in the diagnosis of malignant tumors in the oral and maxillo-facial region

Thermographic images of 48 cases of malignant tumors were analyzed and compared with those of other lesions: 93 cases of acute inflammation, 48 cases of chronic inflammation, 48 cases of benign tumors and 28 cases of cystic lesions. The majority of the cases with malignant tumors showed higher skin temperature over the affected area, but usually not so remarkable such as those of the cases with acute inflammation. The border of the thermal pattern of the tumors showed the tendency to be unclear. Both malignant tumors and acute inflammation appeared to cause an increase in skin temperature of the common carotid artery region on the affected side as compared with the opposite side. Malignant tumors showed the tendency that the temperature of the common carotid artery region of the affected side is equal or lower than the affected region in many cases. It is suggested that with further sophistication of the system suitable for the maxillofacial region, thermography may serve a role in the clinical diagnosis of malignant tumors.

Pain, thermal sensation and cooling rates of hands while touching cold materials.

Hand cooling and resulting comfort and pain were studied in 12 subjects, while touching six different materials (polyurethane foam, wood, nylon, rustproof steel, aluminium, and temperature-controlled metal) which were initially at ambient temperature. This was done for three ambient temperatures (-10 degrees, 0 degree and 10 degrees C), after pre-exposure exercise or rest, with bare hands or while wearing gloves. The observed cooling curves were analysed as Newtonian cooling curves. The observed time constants appeared to be significantly related to the materials' contact coefficients, the presence of hand protection, the preceding activity, and the interaction between contact coefficient and the presence of hand protection. These parameters also allowed a good description of the time constant (r2 = 0.8) of the related cooling curves. Thermal and pain sensation could be described in terms of the local skin temperature, ambient temperature and hand protection. Equal pain and thermal levels were associated with lower temperatures of the back of the hand than of the contact side. The slightly painful condition was associated with a skin temperature of 16 degrees C for the back and 19 degrees C for the palm of the hand. The pain level appeared to be inversely related to cooling speed. Skin freezing occurred at higher skin temperatures when touching cold objects than when exposed to cold air as a result of reduced supercooling. The regression equations determined allowed calculations to be made of safety limits for hand cooling while in contact with a wide range of materials.

腰神経根ブロック前後の皮膚温変化パターンの定性的検討

41 patients (lumbar canal stenosis: 21, lumbar disc herniation: 18, others: 4) with lumbosacral radicular symptoms were examined for skin temperature before and after the nerve root infiltration (L5: 31 roots, S1: 10 roots). Before the nerve root infiltration, the low skin temperature areas were observed in 15 patients (36.5%). After infiltoration, skin temperature rose in 26 patients (63.4%). 62 patients (all lumbar disc herniation L5: 36, S1: 26) with single root disturbance were examined for the area of sensory disturbance. The high skin temperature areas were similar to the area of sensory disturbance at both L5 and S1. We thought that one of the causes of increased skin temperature was sympathetic nerve system.