Differences In Skin Temperature Research Articles

Integrating artificial intelligence for optimal thermal comfort: A design approach for electric heating textiles aligned with user preferences

Human thermal comfort, crucial for well-being and productivity, is often improved by personal comfort systems that offer tailored control over environmental conditions while promoting energy efficiency. Previous studies have explored various textile technologies in thermoregulation systems according to user preferences. However, limited research has focused on temperature prediction by artificial intelligence to maximize thermal comfort for varied users. This study proposes a design approach to optimize thermal comfort in electric heating textiles using artificial intelligence, considering user preferences related to age and gender differences. A fuzzy logic model is established as a proof of concept for temperature regulation by varying ambient temperature, followed by developing an artificial neural network model to predict the optimal temperature for maximum comfort. Subsequently, a smart electric heating jacket is fabricated to assess preferred heating temperatures among 50 subjects with varying ages and genders. Results from the artificial neural network model show promising temperature prediction, while subject tests reveal significant differences in skin temperatures based on gender. This emphasizes the need for artificial intelligence-based heating e-textiles to accommodate diverse user needs. The study’s findings are expected to contribute to intelligent temperature regulation in thermal textiles and wearables, benefitting both the industry and consumers through customized heating products.

A comprehensive study on the impacts of thermal comfort on occupants’ thermophysiology and cognitive performances in a radiant cooling environment using physiological measurements

Radiant cooling (RC) systems are increasingly implemented in public buildings to enhance human thermal comfort and reduce building energy consumption. The quality of the indoor thermal environment significantly impacts occupants’ learning and work performance. This investigation explores indoor occupants’ dynamic physiological regulation, thermal comfort, and cognitive performance under radiant whole-wall cooling (RWWC) systems. Twenty-eight participants underwent a summer exposure test task at varying ambient temperatures, yielding four collected data types: indoor physical parameters, physiological parameters (including skin temperature (ST), heart rate (HR)/heart rate variability (HRV), and electroencephalography (EEG)), performance index (PI), and thermal perception. Results indicate that the RWWC system notably improves thermal perception and comfort, with 93 % of participants reporting comfort at a target temperature of 24℃. Air temperature (AT) exerted the most significant effect on changes in ST on the right upper arm (p < 0.01) and left hand back (p < 0.01) at 30℃ compared to the 22℃. The difference in whole-body mean skin temperature (MST) is 2.68℃. The HR decline was more pronounced in higher temperatures, and the HRV representativeness index approached ‘1′ at 24℃. PI was affected by temperature and task type, displaying a non-linear correlation with AT (R2 = 0.6056) and an inverted “U” shaped curve with TSV (R2 = 0.9523). Thermal perception correlates with MST, HRV, and EEG. The study carries implications for the reasonable design of comfortable and healthy RC environments.

Brown Adipose Tissue Activity and Childhood Exposure to Cold Are Associated With Hot Flashes at Menopause.

Hot flashes (HFs) are experienced as sudden sensations of heat. We hypothesized that brown adipose tissue (BAT) activation could increase the likelihood of HFs in winter. The aim of this study was to test whether women with more BAT activity were more likely to experience self-reported or biometrically measured HFs. Women aged 45-55 years (n = 270) participated in face-to-face interviews and anthropometric and ambulatory measures. Level of BAT activity was estimated from the difference in supraclavicular skin temperature measured by infrared thermography before and after cooling. Logistic regressions were applied to examine whether bothersome HFs (yes/no) during the past 2 weeks were associated with BAT activity, adjusting for menopausal status, childhood exposure to cold, waist/hip ratio, and self-reported health. Linear regressions were used to examine the frequency of self-reported and biometrically measured HFs during the study period and BAT activity, adjusting for potential confounders. Menopausal status, childhood exposure to cold, waist-to-hip ratio (WHR), and self-reported health were associated with both BAT activity and HFs. After adjusting for potential confounders, an increase in BAT activity almost tripled the likelihood of bothersome HFs (OR 2.84, 95% CI 1.26-6.43). In linear regressions, BAT activity was not associated with frequency of subjective or objective HFs during the study period, but childhood exposure to cold was associated with subjective HF report (β = 0.163, p = 0.010). To our knowledge, this is the first study of BAT activation and HFs. Our results support a role for BAT activity in HF experience. Therefore, we encourage further examination of the role of BAT, as well as childhood exposure to cold, in HFs.

Sex differences in body temperature and thermal perception under stable and transient thermal environments: A comparative study

Sex difference stands as a crucial factor necessitating consideration in personalized thermal environment control, with the mechanisms of its emergence potentially differing across different thermal environments. However, a comparative analysis of sex differences regarding body temperature (skin and core body temperature) and thermal perception across different environments is lacking. A stable environmental experiment (comprising three conditions: 16 °C, 20 °C, and 24 °C) and a transient environmental experiment (involving a whole-body step-change from 19 °C to 35 °C and back to 19 °C) were conducted, with participation from 20 young males and 20 young females. Skin temperature and core body temperature were continuously recorded during the experiments, and three types of thermal perceptions were regularly collected. The results showed that: (1) The impact of thermal environment on females' skin temperature surpassed that on males, in stable environment, with every 1 °C rise in ambient temperature, the mean skin temperature increased by 0.28 °C for males and 0.35 °C for females respectively; in transient environment, females' mean skin temperature raise and fell at a faster rate. (2) Males exhibited stronger thermal regulation abilities than females, particularly evident during sudden increase in ambient temperature (from 19 °C to 35 °C), where the reduction magnitude of males' core body temperature was notably larger. (3) Whether in stable or transient environments, significant sex differences often occurred in skin temperature and thermal sensation at distal parts, particularly at the hand. (4) Males typically fed back higher levels of thermal comfort and thermal acceptability than females, suggesting that in addition to physiological sex differences, psychological sex distinctions also play a role. In summary, personalized design for stable thermal environment can focus on sex differences in skin temperature, while transient thermal environment requires consideration of both skin temperature and core body temperature. A comprehensive consideration of physiological and psychological sex differences aids in creating personalized thermal environments with greater precision.

Effects of fan cooling with an air-perfused rucksack on physiological and perceptual strains in young men while running in uncompensable hot environment.

Cooling devices reduce thermal strain during pre-, between-, and postexercise. However, their efficacy during moderate/intensity runs in hot conditions with airflow equivalent to the running speed remains unclear. This study assessed physiological and perceptual responses to neck and upper back fan-cooling through an air-perfused rucksack under such conditions. Ten young men ran at 60% V̇O<inf>2peak</inf> for 30 min in 35 °C, 50% relative humidity with (FAN) and without (CON) air-perfused rucksacks with a hood in a randomized order. Headwind equal to running speed was provided in both conditions. The fan-cooling trial consisted of upper back and neck fan cooling with airflow at 4-5 m/s via two fans attached on either side of the rucksack. Rectal and skin temperatures, whole-body thermal sensation, thermal comfort, and changes in body mass were measured. Upper back skin temperature and thermal sensation were significantly lower throughout the exercise in the FAN than in the CON, whereas thermal comfort was significantly higher at 15-40 min in the FAN (all P≤0.05). Heart rate elevation during 30 min of running was attenuated in the FAN compared to that in the CON (P≤0.05). No significant differences in rectal and mean skin temperatures, or total body mass loss were observed between the two trials. These results indicate that additional fan-cooling on the upper back and neck during running in uncompensable hot conditions with a headwind had limited physiological benefits. However, whole-body-based thermal sensation and comfort are partially improved with the use of an air-perfused rucksack.

Skin Temperature Following Total Knee Arthroplasty: A Longitudinal Observational Study

BackgroundTotal knee arthroplasty (TKA) is the most effective method of pain relief and increased functional status for end-stage knee arthritis. We aimed to assess in patients undergoing unilateral, primary TKA whether the temperature of the operated limb, compared to the nonoperative limb, remains elevated up to 1 year postoperatively. MethodsUsing a prospective, longitudinal, observational study design, 1,094 patients were enrolled, and 889 patients completed a minimum of 4 out of 5 follow-up appointments. There were 864 patients who had a normal postoperative course, while 25 patients were deemed to have a superficial or deep infection. Skin temperatures were measured using an infrared thermometer on the operated and nonoperated knees preoperatively, at 2, 6, 12 weeks, and 1 year postoperatively. A subgroup analysis was performed on the 25 patients deemed to have a superficial or deep infection. ResultsThere was a statistically significant increase in skin temperature in the operated versus nonoperated knee at every follow-up, with a P < .001. However, the effect size was small at the 1-year follow-up, with a mean difference in skin temperature of 0.3 °C. In the infected subgroup, there was a statistically significant difference in skin temperature at 2, 6, and 12 weeks, with a greater difference in skin temperature between the operated and nonoperated knees (4.05 versus 3.78 °C in the noninfected). However, there was little clinical difference (0.27 °C) at 2 weeks between infected and noninfected patients. ConclusionsThis study could improve postoperative interactions between patients and surgeons. It is normal for skin temperature post-TKA to increase initially and improve over time, but it can take up to 1 year before there is little clinical difference. Because of the small difference in the rise of skin temperature between infected and noninfected patients, there is little indication that skin temperature is a reliable indicator of infection.

Study on personal comfort heating system and human thermal comfort in extremely low-temperature building environments

Exposure to extremely low-temperature building environments around −20 °C causes various hazards to human health. However, few studies have studied human thermal comfort and physiological response in such environments, nor the personal comfort heating system. Thus, this study investigated the heating characteristics of personal comfort heating system and their effects on thermal responses and thermophysiological parameters in extremely low-temperature building environments. We conducted experimental tests and questionnaires in a cryogenic enthalpy difference laboratory with air temperature ranging from −21.2 to −15.6 °C and a relative humidity of 55 %. Eight experimental conditions were designed with several heating measures (heating mat, heating gloves, heating cushion and airwarmer). The heating parameters of the personal comfort heating systems as well as the subjective evaluations and skin temperature of the subjects were recorded and analyzed. The results showed that the airwarmer confinement box condition had a corrective power of up to 38.3 K. The overall thermal sensation vote and overall thermal comfort vote were maintained at 0.25 and −0.25. Further, we found that the face, hands, calves and feet got cold easier with the largest skin temperature difference of −4.9, −8.1, −6.7 and −7.6 °C, respectively. Besides, the relationships between thermal responses and between thermal responses and skin temperature were examined, as well as a thermal comfort assessment methodology was established for extremely low-temperature environments.

Fourteen Days of Cool Water Immersion Does Not Modify an Indirect Index of Brown Adipose Tissue Activation

Military divers often operate in cold water eliciting reductions in skin and core temperatures despite the use of thermal protection. Decreases in body temperatures triggers shivering and non-shivering thermogenesis, the latter of which is largely due to the activation of brown adipose tissue (BAT). Ten days of cool air exposure (15-16°C) and seven days of cold-water exposure (14°C) augments non-shivering thermogenesis. However, it is unknown if repeated exposure to cool head out water immersion (CWI) modifies non-shivering thermogenesis. This study tested the hypothesis that fourteen days of CWI for 4 h/d will increase BAT activation. Healthy adults were randomly assigned to either CWI (n=10, 5 women) or thermoneutral head out water immersion (35°C, TNW, n=9, 5 women). CWI and TNW exposures were 4 h in duration and were completed once daily for 14 d in a 16-d period. CWI consisted of the initial immersion in 28°C water and following a 0.5°C reduction in rectal temperature, the water temperature was increased to up to 30°C so that a mild hypothermic state was maintained during the 4 h. Rectal temperature, oxygen uptake (indirect calorimetry), and supraclavicular and trapezius skin temperatures (thermocouples) were measured preexposure and during the middle 3 h of immersion. This analysis was a part of a larger study. Therefore, during the 3 h period, all participants were exposed to hypoxia (FiO2: 0.14). The supraclavicular-trapezius skin temperature difference (Tsk diff) provided an index of BAT activation. Data collected on Day 1 and Day 14 are presented (mean ± SD). Peak decreases in rectal temperature from preexposure were greater in CWI (-0.7±0.3°C) vs. TNW (-0.2±0.4°C, p&lt;0.001) and did not differ between Day 1 and Day 14 in either group (p=0.923). Average oxygen uptake was higher in CWI (0.54±0.09 L/min) vs. TNW (0.38±0.12 L/min, p&lt;0.001) and did not differ between Day 1 and Day 14 in either group (p=0.443). Average Tsk diff did not differ between groups (CWI: 2.2±0.8°C, TNW: 1.6±0.1.1°C, p=0.090) and did not differ between Day 1 and Day 14 in either group (p=0.111). Peak decreases in rectal temperature were significantly correlated with average oxygen uptake (r=-0.552, p&lt;0.001) but not average Tsk diff (r=-0.152, p=0.362). Fourteen days of CWI did not modify thermogenesis (oxygen uptake) nor BAT activation, as estimated from Tsk diff. However, a potential interaction between moderate hypoxia and BAT activation during CWI cannot be excluded. Future work is required to determine the effect of mild hypothermia, such as that experienced by divers operating in cold water even with thermal protection, on more direct markers of BAT activation. Funding: Offce of Naval Research (N00014-20-1-2593 &amp; N00014-21-1-2276). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effect of a vapor barrier in combination with active external rewarming for cold-stressed patients in a prehospital setting: a randomized, crossover field study

BackgroundUse of a vapor barrier in the prehospital care of cold-stressed or hypothermic patients aims to reduce evaporative heat loss and accelerate rewarming. The application of a vapor barrier is recommended in various guidelines, along with both insulating and wind/waterproof layers and an active external rewarming device; however, evidence of its effect is limited. This study aimed to investigate the effect of using a vapor barrier as the inner layer in the recommended “burrito” model for wrapping hypothermic patients in the field.MethodsIn this, randomized, crossover field study, 16 healthy volunteers wearing wet clothing were subjected to a 30-minute cooling period in a snow chamber before being wrapped in a model including an active heating source either with (intervention) or without (control) a vapor barrier. The mean skin temperature, core temperature, and humidity in the model were measured, and the shivering intensity and thermal comfort were assessed using a subjective questionnaire. The mean skin temperature was the primary outcome, whereas humidity and thermal comfort were the secondary outcomes. Primary outcome data were analyzed using analysis of covariance (ANCOVA).ResultsWe found a higher mean skin temperature in the intervention group than in the control group after approximately 25 min (p < 0.05), and this difference persisted for the rest of the 60-minute study period. The largest difference in mean skin temperature was 0.93 °C after 60 min. Humidity levels outside the vapor barrier were significantly higher in the control group than in the intervention group after 5 min. There were no significant differences in subjective comfort. However, there was a consistent trend toward increased comfort in the intervention group compared with the control group.ConclusionsThe use of a vapor barrier as the innermost layer in combination with an active external heat source leads to higher mean skin rewarming rates in patients wearing wet clothing who are at risk of accidental hypothermia.Trial registrationClinicalTrials.gov identifier: NCT05779722.

Hot, cold, or just right? An infrared biometric sensor to improve occupant comfort and reduce overcooling in buildings via closed-loop control

To improve occupant comfort and save energy in buildings, we have developed a closed-loop air conditioning (AC) sensor-controller that predicts occupant thermal sensation from the thermographic measurement of skin temperature distribution, then uses this information to reduce overcooling (cooling-energy overuse that discomforts occupants) by regulating AC output. Taking measures to protect privacy, it combines thermal-infrared (TIR) and color (visible spectrum) cameras with machine vision to measure the skin-surface temperature profile. Since the human thermoregulation system uses skin blood flow to maintain thermoneutrality, the distribution of skin temperature can be used to predict warm, neutral, and cool thermal states. We conducted a series of human-subject thermal-sensation trials in cold-to-hot environments, measuring skin temperatures and recording thermal sensation votes. We then trained random-forest classification machine-learning models (classifiers) to estimate thermal sensation from skin temperatures or skin-temperature differences. The estimated thermal sensation was input to a proportional integral (PI) control algorithm for the AC, targeting a sensation level between neutral and warm. Our sensor-controller includes a sensor assembly, server software, and client software. The server software orients the cameras and transmits images to the client software, which in turn assesses occupant skin temperature distribution, estimates occupant thermal sensation, and controls AC operation. A demonstration conducted in a conference room in an office building near Houston, TX showed that our system reduced overcooling, decreasing AC load by 42% when the room was occupied while improving occupant comfort (fraction of “comfortable” votes) by 15 percentage points.

Analysis of asymmetric thermal sensation under the coupling effect of temperature difference in multiple parts of human body

Responding to thermal comfort based on physiological indicators is a broad and reliable research method. How to use skin temperature to predict thermal comfort in a non-uniform environment is of great significance. 24 volunteers were selected for testing with local radiant heating in Kitakyushu, Japan. It was found that the most obvious skin temperature difference value occurred between left and right thighs while heating after 30 min, which would exceed 5 °C. The asymmetric thermal sensation votings (ATSV) and the skin temperature difference were significantly influenced while changing radiation intensity and radiation distance, the ATSV of the subjects in the small space was about 0.3 lower than that of the subjects in the large space. Increasing the radiation intensity, the TSV of the small space decreased by about −0.5, which can be seen that higher radiation intensity may bring lower value of the TSV. A prediction model of the ATSV and skin temperature difference was established and the sensitivity analysis was performed on the different body parts that significantly affected the ATSV, and the dominant factors affecting the ATSV were obtained. This paper complements the non-uniform thermal environment prediction method.

Temperature Differences Between Controlled Primary Hypothyroidism and Healthy Patients: An Exploratory Study.

Hypothyroidism is conventionally treated with replacement therapy through levothyroxine (LT4). Despite the improvement in symptoms, cold intolerance persists in some patients. The present study aims to determine whether there is a difference in temperature perception and skin temperature between patients with primary controlled hypothyroidism (PCH) and a group of healthy controls matched for body mass index and age. Secondarily we aimed to determine difference in quality of life. Skin temperature measurements were performed in both groups, both in the central and peripheral regions of the body. In addition, subjects were asked about their perception of temperature in a temperature-controlled room; anthropometric measurements were taken, their quality of life was assessed using the ThyPRO-39, and a thyroid hormone profile was performed. Eleven patients in the PCH group and 30 patients in the control group were studied. It was found that the group with PCH presented a significantly lower palmar temperature than the control group [mean (SD) of 32.05 (1.79) vs 33.10 (1.30) oC, P = .046]. A mediation model showed a direct effect. Temperature perception was equal between groups. The median (interquartile range) of ThyPRO was 8 (5.2) points in the control group vs 21.8 (13.5) in the group of controlled hypothyroidism, P < .001. These results suggest that, despite LT4 treatment, patients continue to present abnormalities in thermogenesis-related thermogenesis, and this may be due to a lack of hormonal adaptation to environmental changes and physiological demands, leading to lower body temperatures and increased sensitivity to cold.

Comparative study on the efficacy of PRP gel and UC-MSCs gel as adjuvant therapies in the treatment of DFU wounds.

Diabetic foot ulcer (DFU) is a common and serious complication of diabetes, and its treatment is challenging. Platelet-rich plasma (PRP) gel and umbilical cord mesenchymal stem cells (UC-MSCs) gel have been concerned as new therapies for DFU in recent years, and comparative studies on the efficacy and mechanisms of these methods, however, are rarely reported. Thirty patients with DFU were selected and divided into the PRP group and the UC-MSCs group, and wound healing, foot blood vessels (ABI index), infection index (CRP), neuropathy symptoms (TCSS score), and foot skin temperature before and after treatment were compared between the two groups. SPSS 21.0 was used for statistical analysis. The results showed that the efficacy of the UC-MSCs gel group was significantly better than that of the PRP group in terms of wound healing rate, time to complete wound closure, ABI index, CRP level and TCSS score. No statistically significant difference in foot skin temperature was observed between the two groups. The efficacy of UC-MSCs gel is significantly superior to that of PRP gel in the treatment of DFU, with shortened time to complete wound closure, increased wound healing rate, better pain and infection control, and improved vascular and neurological symptoms.

Combining protection with skin health: In vivo studies of an innovative gelatin/tannic acid-based hydrogel patch to prevent PPE-related skin lesions

The prolonged use of Personal Protective Equipment (PPE) can lead to skin problems due to persistent pressure, friction, and tension. This issue has prompted the exploration of solutions to protect the skin while maintaining the effectiveness of the PPE. This study aimed to evaluate the in vivo effectiveness of a gelatin/tannic acid-based hydrogel patch positioned beneath a mask to alleviate skin damage resulting from mask-wearing. To understand the pressure exerted by PPE, in vitro tests were conducted to measure the tensile strength of three types of facial masks. The FFP2 masks exhibited the highest tensile strength and were selected for subsequent in vivo biometric investigations. Biometric parameters were evaluated using the Flir E50bx® thermographic camera, Corneometer®, MoistureMap®, Sebumeter®, Tewameter®, and VISIA® systems. The results showed that when the hydrogel patch was used under the mask, there were no significant differences in facial skin temperature, sebum levels, or TEWL values (p > 0.05). However, a statistically significant increase in skin hydration and a decrease in frontal redness (p < 0.05) were observed. Consumer acceptance was assessed through sensory analysis questionnaires. In summary, the observed attenuation of physiological changes in the facial area and the positive consumer feedback suggest that this polymeric film-forming system is a simple yet effective solution to prevent PPE use-related skin issues.

Thermal sensation prediction model for high-speed train occupants based on skin temperatures and skin wettedness.

Passenger thermal comfort in high-speed train (HST) carriages presents unique challenges due to factors such as extensive operational areas, longer travel durations, larger spaces, and higher passenger capacities. This study aims to propose a new prediction model to better understand and address thermal comfort in HST carriages. The proposed prediction model incorporates skin wettedness, vertical skin temperature difference (ΔTd), and skin temperature as parameters to predict the thermal sensation vote (TSV) of HST passengers. The experiments were conducted with 65 subjects, evenly distributed throughout the HST compartment. Thermal environmental conditions and physiological signals were measured to capture the subjects' thermal responses. The study also investigated regional and overall thermal sensations experienced by the subjects. Results revealed significant regional differences in skin temperature between upper and lower body parts. By analyzing data from 45 subjects, We analyzed the effect of 25 variables on TSV by partial least squares (PLS), from which we singled out 3 key factors. And the optimal multiple regression equation was derived to predict the TSV of HST occupants. Validation with an additional 20 subjects demonstrated a strong linear correlation (0.965) between the actual TSV and the predicted values, confirming the feasibility and accuracy of the developed prediction model. By integrating skin wettedness and ΔTd with skin temperature, the model provides a comprehensive approach to predicting thermal comfort in HST environments. This research contributes to advancing thermal comfort analysis in HST and offers valuable insights for optimizing HST system design and operation to meet passengers' comfort requirements.

Venous dilation effect of hot towel (moist and dry heat) versus hot pack for peripheral intravenous catheterization: a quasi-experimental study

BackgroundHeat application before peripheral intravenous catheterization is recommended for venous dilation. Hot pack application enlarges the venous diameter in healthy adults; however, hot towels (moist and dry heat) are used often in some medical cases. However, it is unclear whether hot towel application promotes venous dilation better than hot pack application. This study compared the venous dilation effect of using a hot towel (moist and dry heat) to a hot pack before applying the tourniquet at an access site for peripheral intravenous catheterization.MethodsEighty-eight healthy females aged 18–29 years were recruited for this quasi-experimental study. They underwent three types of heat applications (hot pack, moist hot towel, and dry hot towel [moist hot towel wrapped in a dry plastic bag], all of which were warmed to 40 ± 2 °C and performed for 7 min) to their forearm and tourniquet application for 30 s after each heating. Venous diameter and depth were measured using ultrasonography, and venous palpability and visibility (venous assessment score) was observed as venous dilatation effects. In addition, the skin temperature, stratum corneum hydration, and subjective evaluation of the warmth were measured.ResultsThere were no significant differences in venous diameter and assessment scores after intervention between the dry hot towel and the hot pack groups, and the effect size was negligible (Cohen’s d < 0.20). However, these measurements were significantly lower for the moist hot towel than for the other two heat applications (P < .001). Although there was no significant difference in skin temperature and warmth rating score between the dry hot towel and the hot pack, these were significantly lower for the moist hot towel than for the other two heat applications (P < .001). The amount of change in stratum corneum hydration of the dry hot towel was not significantly different from that of the hot pack; however, that of the moist hot towel was significantly larger than that of the other two heat applications (P < . 001.)ConclusionsA method in which a towel warmed in hot water is wrapped in a dry barrier may be an alternative to a hot pack.Trial registrationThis study was registered with University Hospital Medical Information Network in Japan (Registration No.: UMIN000048308. Registered on July 7, 2022).

Increases in local skin temperature correlate with spontaneous foot lifting and heat hyperalgesia in both incisional inflammatory models of pain.

This study investigated if a localized increase in skin temperature in rat models of incisional and inflammatory pain correlates with the intensity of spontaneous and evoked pain behaviors. Anesthetized rats received either a 20-mm longitudinal incision made through the skin, fascia, and muscle of the plantar hind paw or an injection of complete Freund adjuvant into the plantar hind paw of anesthetized rats to induce local inflammation. Spontaneous and evoked pain behaviors were assessed, and changes in skin temperature were measured using a noncontact infrared thermometer. There were no differences in skin temperature between the ipsilateral and contralateral hind paw before the incision or inflammation. Skin temperature increased at 2 hours after hind paw plantar incision or 1 day after inflammation of the affected paw, which gradually returned to baseline by the first day and fourth days after treatment, respectively. The increase in skin temperature correlated with the intensity of spontaneous pain behaviors and heat but not with mechanical allodynia. Our results suggest that a simple measurement of localized skin temperature using a noncontact infrared thermometer could measure the extent of spontaneous pain behaviors and heat hyperalgesia following plantar incision or inflammation in animals. In the absence of a reliable objective marker of pain, these results are encouraging. However, studies are warranted to validate our results using analgesics and pain-relieving interventions, such as nerve block on skin temperature changes.

Experimental evaluation of partial body cryotherapy unit with gas supply regulation

The partial body cryotherapy is a medical treatment that uses a physical factor to stimulate the main part of body surface. Today physicians do not have the technical ability to improve this method towards predictive and personalized medicine. Different patients have different dimensions and other features (physique, sex, age, adaptation level, etc.). However, physicians are able to set only the exposure duration. In this case, the skin cooling uncertainty and non-uniformity reduces the safety and effectiveness of cryoexposure. The key to upgrade cryotherapy is increasing the number of parameters to achieve a less skin temperature difference at the end of exposure and to plan a given skin cooling for different patients by reducing the intensity of cooling. This article is aimed to experimentally evaluate the novel partial body cryotherapy unit that has the ability to regulate: the gas temperature in the cryocabin; the inlet jet direction and the exposure duration. Based on the proposed model of a human as an object of cooling, using the developed unit, the adopted cryoexposure protocol and the presented approach to the analysis of infrared images, experiments were conducted. Data were obtained on the participant's interview and skin temperature. It is shown that the approach used is safety treatment and make it possible to obtain an improved and controlled skin temperature distribution at the end of cryoexposure. It might be relevant for improving cryotherapy protocols and for equipment development.

Analysing the impact of cloth fabrics on skin temperature during and after exercise using an FDM model

This study presents a 1D finite difference model that examines the influence of cloth fabrics on skin temperature during and after exercise, considering the complex nature of the human body and its susceptibility to infections and viruses. The aim is to design comfortable, high-quality fabrics that minimize potential issues caused by body temperature fluctuations. The model incorporates various physical, physiological, and thermal parameters of cloth to develop protective clothing suitable for exercise. Numerical results were compared to previous studies that analyzed skin temperature without clothing to validate the model’s accuracy. The findings indicate a minimal difference in skin temperature when wearing cotton and polyester cloth, with polyester fabric demonstrating superior characteristics such as stretchability, durability, and sweat resistance. The thermal information obtained from this model can be utilized to design appropriate clothing for diverse weather conditions, ultimately enhancing the performance and comfort of athletes, military personnel, and individuals engaged in physically demanding work. Additionally, the model can aid in developing thermal stress protocols for infection treatment and provide guidelines for physical activity to promote healthy living. This research contributes to the field of materials research by offering valuable insights into the design and development of protective clothing for exercise. By understanding the impact of cloth fabrics on skin temperature, advancements can be made in creating clothing that optimizes human comfort and performance.

Improvement and validation of the Tanabe model to simulate human thermal behaviors in hot environments at high altitudes

Exposure to hypobaric and hyperthermic environments can easily induce heat stress and affect operational efficiency. Thermal manikins represent advanced instruments for simulating human thermal behaviors in complex ambient conditions. However, currently, no thermal manikins are coupled with a human thermoregulatory model adapted for high-altitude environments. This study aimed to develop the traditional Tanabe model by incorporating air pressure into the calculation of the convective and evaporative heat transfer coefficients, therefore local skin temperature and thermal sensation at high altitudes could be predicted. To validate the model, these predicted variables were also measured in human thermal physiology experiments at the altitude of 0 m (101.3 kPa) and 4000 m (56.04 kPa) with an ambient temperature of 35 °C. The results demonstrated that local and weighted average skin temperatures were consistent between simulation and experimental results. The maximum deviation between experiments and simulation did not exceed 0.7 °C at segments except hand and foot, and 2.5 °C at each segment, at the altitude of 0 m and 4000 m respectively. The R2 values of Gaussian distribution and linear regression results concerning the experimental and simulation weighted average skin temperature and the PMV score at the altitudes of 0 m and 4000 m were 0.966, 0.975, 0.857, and 0.851. These findings suggest that differences in skin temperature and thermal sensation at different altitudes are influenced by variations in evaporation and dry heat exchanges. The improved Tanabe model in this study was validated and could be further utilized in investigating heat transfer processes and coefficients between the skin surface and the environment and developing control algorithms for thermal manikins.