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

BACKGROUND: Use 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. METHODS: In 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). RESULTS: We 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. CONCLUSIONS: The 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 REGISTRATION: ClinicalTrials.gov identifier: NCT05779722.

Inspiratory muscles pre-activation in young swimmers submitted to a tethered swimming test: effects on mechanical, physiological, and skin temperature parameters.

Inspiratory muscles pre-activation (IMPA) has been studied to improve subsequent performance in swimming. However, the effects of IMPA on various parameters in swimmers are still unknown. Therefore, this study aimed to investigate the effects of IMPA on the mechanical parameters, physiological responses, and their possible correlations with swimming performance. A total of 14 young swimmers (aged 16 ± 0 years) underwent a 30-s all-out tethered swimming test, preceded or not by IMPA, a load of 40% of the maximal inspiratory pressure (MIP), and with a volume of 2 sets of 15 repetitions. The mechanical (strength, impulse, and fatigue index) and physiological parameters (skin temperature and lactatemia) and the assessment of perceived exertion and dyspnea were monitored in both protocols. The IMPA used did not increase the swimming force, and skin temperature, decrease blood lactate concentration, or subjective perception of exertion and dyspnea after the high-intensity tethered swimming exercises. Positive correlations were found between mean force and blood lactate (without IMPA: r = 0.62, P = 0.02; with IMPA: r = 0.65, P = 0.01). The impulse was positively correlated with blood lactate (without IMPA: r = 0.71, P < 0.01; with IMPA: r = 0.56, P = 0.03). Our results suggest that new IMPA protocols, possibly with increased volume, should be developed in order to improve the performance of young swimmers.

Plateau in Core Temperature during Shorter but Not Longer Work/Rest Cycles in Heat.

This study compared physiological responses to two work/rest cycles of a 2:1 work-to-rest ratio in a hot environment. In a randomized crossover design, fourteen participants completed 120 min of walking and rest in the heat (36.3 ± 0.6 °C, 30.2 ± 4.0% relative humidity). Work/rest cycles were (1) 40 min work/20 min rest [40/20], or (2) 20 min work/10 min rest [20/10], both completing identical work. Core temperature (Tc), skin temperature (Tsk), heart rate (HR), nude body mass, and perception of work were collected. Comparisons were made between trials at equal durations of work using three-way mixed model ANOVA. Tc plateaued in [20/10] during the second hour of work (p = 0.93), while Tc increased in [40/20] (p < 0.01). There was no difference in maximum Tc ([40/20]: 38.08 ± 0.35 °C, [20/10]: 37.99 ± 0.27 °C, p = 0.22) or end-of-work Tsk ([40/20]: 36.1 ± 0.8 °C, [20/10]: 36.0 ± 0.7 °C, p = 0.45). End-of-work HR was greater in [40/20] (145 ± 25 b·min-1) compared to [20/10] (141 ± 27 b·min-1, p = 0.04). Shorter work/rest cycles caused a plateau in Tc while longer work/rest cycles resulted in a continued increase in Tc throughout the work, indicating that either work structure could be used during shorter work tasks, while work greater than 2 h in duration may benefit from shorter work/rest cycles to mitigate hyperthermia.

Influences of Indoor Air Temperatures on Empathy and Positive Affect.

The consequences of climate change are already visible, and yet, its effect on psychosocial factors, including the expression of empathy, affect, and social disconnection, is widely unknown. Outdoor conditions are expected to influence indoor conditions. Therefore, the aim of this study was to investigate the effect of indoor air temperature during work hours on empathy, positive and negative affect, and social disconnection. Participants (N = 31) were exposed, in a cross-over design, to two thermal conditions in a simulated office environment. Questions on empathy and social disconnection were administered before and after the exposure to each condition, while affect was measured throughout the day. Subjective thermal sensation and objective measures of mean skin temperature were considered. The results indicated a significant difference in empathy (F(1, 24) = 5.37, p = 0.03, with an η2 = 0.126) between conditions. Participants reported increases in empathy after exposure to the warm condition compared to the cool condition, in which reductions in empathy were reported. Although the same pattern was observed for positive affect, the difference was smaller and the results were not significant. Thermal sensation had a significant effect on changes in empathy too (F(1, 54) = 7.015, p = 0.01, with an R2 = 0.115), while mean skin temperature had no effect on empathy (F(1, 6) = 0.53, p = 0.89, with an R2 = 0.81). No effects were observed for positive and negative affect and social disconnection. Longitudinal studies are needed to support these findings.

A thermoregulation model based on the physical and physiological characteristics of Chinese elderly.

Given the increasing aging population and rising living standards in China, developing an accurate and straightforward thermoregulation model for the elderly has become increasingly essential. To address this need, an existing one-segment four-node thermoregulation model for the young was selected as the base model. This study developed the base model considering age-related physical and physiological changes to predict mean skin temperatures of the elderly. Measured data for model optimization were collected from 24 representative healthy Chinese elderly individuals (average age: 67 years). The subjects underwent temperature step changes between neutral and warm conditions with a temperature range of 25-34 °C. The model's demographic representation was first validated by comparing the subjects' physical characteristics with Chinese census data. Secondly, sensitivity analysis was performed to investigate the influences of passive system parameters on skin and core temperatures, and adjustments were implemented using measurement or literature data specific to the Chinese elderly. Thirdly, the active system was modified by resetting the body temperature set points. The active parameters to control thermoregulation activities were further optimized using the TPE (Tree-structured Parzen Estimator) hyperparameter tuning method. The model's accuracy was further verified using independent experimental data for a temperature range of 18-34 °C for Chinese elderly. By comprehensively considering age-induced thermal response changes, the proposed model has potential applications in designing and optimizing thermal management systems in buildings, as well as informing energy-efficient strategies tailored to the specific needs of the Chinese elderly population.

Blood pressure, pulse rate, and skin temperature during hot-water bathing in real-world settings among community-dwelling older adults: the HEIJO-KYO Study.

BACKGROUND: Home hot-tub bathing substantially increases drowning mortality rates among older adults in Japan. Previous laboratory studies on hemodynamic responses during hot-tub bathing have been inconsistent depending on the thermal conditions. Furthermore, real-world hemodynamic changes that occur during bathing remain poorly understood. This study investigated the association between individual thermal states and hemodynamic parameters during hot-tub bathing among community-dwelling older adults. METHODS: In this cross-sectional study conducted between January 2016 and April 2019, which involved 1,479 older adults (median [range] age, 68 [40-90] years), skin temperature on the abdominal surface was measured every minute. Ambulatory blood pressure and pulse rate were recorded at 15-min intervals for 24 h. Participants underwent simultaneous living room temperature measurements in their homes, and the time and methods of bathing were recorded. Associations between skin temperature and hemodynamic parameters during bathing and between the pre-bath living room temperature and in-bath maximum proximal skin temperature were evaluated using mixed-effects and linear regression models, respectively. RESULTS: A 1 °C increase in skin temperature was significantly associated with a 2.41 mmHg (95% confidence interval [CI]: 2.03-2.79) increase in systolic blood pressure and a 2.99 bpm (95% CI: 2.66-3.32) increase in pulse rate, after adjusting for potential confounders, including age, sex, body mass index, antihypertensive medication use, dyslipidemia, diabetes, and living room and outdoor temperatures. Significant interactions were not observed between sex and skin temperature in relation to systolic blood pressure and pulse rate (P = 0.088 and 0.490, respectively). One standard deviation lower living room temperature before bathing was significantly associated with a 0.41 °C (95% CI: 0.35-0.47) higher maximum skin temperature during bathing. CONCLUSIONS: Our findings suggest that pre-bath cold exposure may increase the skin temperature during hot-tub bathing, possibly resulting in excessive hemodynamic changes. This provides a framework for future interventions that utilize pre-bath thermal conditions and bathing environments to prevent bath-related deaths.

Activation of cardiac parasympathetic and sympathetic activity occurs at different skin temperatures during face cooling.

Sufficiently cold-water temperatures (<7°C) are needed to elicit the sympathetic response to the cold pressor test using the hand. However, it is not known if stimulating the trigeminal nerve via face cooling, which increases both sympathetic and cardiac parasympathetic activity, also has a threshold temperature. We tested the hypothesis that peak autonomic activation during a progressive face cooling challenge would be achieved when the stimulus temperature is ≤7°C. Twelve healthy participants (age: 25 ± 3 yr, four women) completed our study. Six pliable bags, each containing water or an ice slurry (34°C, 28°C, 21°C, 14°C, 7°C, and 0°C) were applied sequentially to participants' forehead, eyes, and cheeks for 5 min each. Mean arterial pressure (photoplethysmography; index of sympathetic activity) and heart rhythm (3-lead ECG) were averaged in 1-min increments at the end of baseline and throughout each temperature condition. Heart rate variability in the time [(root mean square of successive differences (RMSSD)] and frequency [high-frequency (HF) power] domains was used to estimate cardiac parasympathetic activity. Data are presented as the increase from baseline ± SD. Mean arterial pressure only increased from baseline in the 7°C (13.1 ± 10.3 mmHg; P = 0.018) and 0°C (25.2 ± 7.8 mmHg; P < 0.001) conditions. Only the 0°C condition increased RMSSD (160.6 ± 208.9 ms; P = 0.009) and HF power (11,450 ± 14,555 ms2; P = 0.014) from baseline. Our data indicate that peak increases in sympathetic activity during face cooling are initiated at a higher forehead skin temperature than peak increases in cardiac parasympathetic activity.

Enhancing physiological recovery and subsequent exercise performance in the heat using a phase-change material cooling blanket.

This study aimed to assess the effect of a phase-change material (PCM) cooling blanket for cooling between exercise bouts on recovery of physiological parameters and subsequent exercise performance in the heat. Eighteen male volunteers were recruited to participate in human trials involving two exhaustive treadmill running bouts (Bout1 for 3 km and Bout2 for 1.5 km) in a climate chamber (temperature = 33 °C; relative humidity = 40%). Participants were randomly subjected to one of two cooling conditions for a 10-min period between exercise bouts: CON: natural cooling; 10-min PCM: with a PCM cooling blanket for 10 min. Several physiological parameters including mean skin temperature (Tskin), oral temperature (Toral), core temperature (Tcore), heart rate (HR), mean arterial pressure (MAP), respiratory rate (RR), peripheral capillary oxygen saturation (SpO2), average running speed and rating of perceived exertion (RPE) scale score were analyzed. The results showed that compared to the CON group, participants in the 10-min PCM group had a significant lower Tskin, Tcore, HR and RR at post-cooling, as well as greater reductions in mean skin temperature (ΔTskin) and core temperature (ΔTcore) from post-Bout1 to post-cooling. Additionally, the 10-min PCM group exhibited significantly lower peak Tcore, peak HR and RPE scale score during Bout2, while the average running speed during Bout2 was significantly higher. The present study suggests that cooling with a PCM cooling blanket can enhance physiological recovery and subsequent exercise performance in the heat.

Mixed-Method Precooling Enhances Self-Paced 20-km Cycling Time-Trial Performance When Apparent Temperature Is >46 °C but May Not Be a Priority in <46 °C.

PURPOSE: Precooling (PreC) may only benefit performance when thermal strain experienced by an individual is sufficiently high. We explored the effect of mixed-method PreC on 20-km cycling time-trial (CTT) performance under 3 different apparent temperatures (AT). METHODS: On separate days, 12 trained or highly trained male cyclists/triathletes completed six 20-km CTTs in 3 different ATs: hot-dry (35 °C AT), moderately hot-humid (40 °C AT), and hot-humid (46 °C AT). All trials were preceded by 30 minutes of mixed-method PreC or no PreC (control [CON]). RESULTS: Faster 2.5-km-split completion times occurred in PreC compared with CON in 46 °C AT (P = .02), but not in 40 °C AT (P = .62) or 35 °C AT (P = .57). PreC did not affect rectal and body temperature during the 20-km CTT. Skin temperature was lower throughout the CTT in PreC compared with CON in 46 °C AT (P = .01), but not in 40 °C AT (P = 1.00) and 35 °C AT (P = 1.00). Heart rate had a greater rate of increase during the CTT for PreC compared with CON in 46 °C AT (P = .01), but not in 40 °C AT (P = .57) and 35 °C AT (P = 1.00). Ratings of perceived exertion (P < .001) and thermal comfort (P = .04) were lower for PreC compared with CON in 46 °C AT only, while thermal sensation was not different between PreC and CON. CONCLUSION: Mixed-method PreC should be applied prior to 20-km CTTs conducted in hot-humid conditions (≥46 °C AT). Alternatively, mixed-method PreC may be a priority in moderately hot-humid (∼40 °C AT) conditions but should not be in hot-dry (∼35 °C AT) conditions for 20-km CTT.

Effects of palm cooling on thermoregulatory-related and subjective indicators during exercise in a hot environment.

Palm cooling is a simple and easily implemented intervention strategy during exercise. We aimed to examine the effects of bilateral palm cooling before and during exercise on thermoregulatory-related and subjective indicators in a hot environment. Ten active men (age: 21 ± 1 years; height 172.2 ± 5.7 cm; weight 67.4 ± 7.2 kg) underwent three experimental trials at the same time of the day, consisting of palm cooling with 12°C (ICE12°C), palm cooling with 0°C (ICE0°C) where vasoconstriction is supposed to occur, and control (CON) trials. After 30 min rest at ambient temperature, participants performed 20 min exercise at 33°C, 60% relative humidity. Rectal temperature, skin temperature, rate of perceived exertion, heart rate, local sweat rate, oxygen uptake, carbon dioxide production, and respiratory exchange ratio did not differ between the trials. Thermal sensation and comfort were lower in the ICE12°C and ICE0°C trials than in the CON trial, but the ICE0°C trial showed a longer duration of cold sensation than the ICE12°C trial. Palm cooling at 12°C and 0°C improved thermal sensation and thermal comfort during exercise in a hot environment, although there was no effect on core body temperature, sweating, and cardiorespiratory function. Bilateral palm cooling at 12°C and 0°C improve subjective indicators during exercise in a hot environment and these effects are slightly greater at 0°C than at 12°C cooling, while having no effect on thermoregulatory-related indicators. These results suggest that bilateral palm cooling at lower temperatures may safely reduce the perception of warmth during exercise in a hot environment.

Mechanistic involvement of noradrenergic neuronal neurotransmitter release in cutaneous vasoconstriction during autonomic dysreflexia in persons with spinal cord injury.

INTRODUCTION: Autonomic dysreflexia (AD) is a potentially life-threatening consequence in high (above T6) spinal cord injury that involves multiple incompletely understood mechanisms. While peripheral arteriolar vasoconstriction, which controls systemic vascular resistance, is documented to be pronounced during AD, the pathophysiological neurovascular junction mechanisms of this vasoconstriction are undefined. One hypothesized mechanism is increased neuronal release of norepinephrine and co-transmitters. We tested this by examining the effects of blockade of pre-synaptic neural release of norepinephrine and co-transmitters on cutaneous vasoconstriction during AD, using a novel non-invasive technique; bretylium (BT) iontophoresis followed by skin blood flow measurements via laser doppler flowmetry (LDF). METHODS: Bretylium, a sympathetic neuronal blocking agent (blocks release of norepinephrine and co-transmitters) was applied iontophoretically to the skin of a sensate (arm) and insensate (leg) area in 8 males with motor complete tetraplegia. An nearby untreated site served as control (CON). Cutaneous vascular conductance (CVC) was measured (CVC = LDF/mean arterial pressure) at normotension before AD was elicited by bladder stimulation. The percent drop in CVC values from pre-AD vs. AD was compared among BT and CON sites in sensate and insensate areas. RESULTS: There was a significant effect of treatment but no significant effect of limb/sensation or interaction of limb x treatment on CVC. The percent drop in CVC between BT and CON treated sites was 25.7±1.75 vs. 39.4±0.87, respectively (P = 0.004). CONCLUSION: Bretylium attenuates, but does not fully abolish vasoconstriction during AD. This suggests release of norepinephrine and cotransmitters from cutaneous sympathetic nerves is involved in cutaneous vasoconstriction during AD.

Observations of cold-induced vasodilation in persons with spinal cord injuries.

STUDY DESIGN: Acute experimental study. OBJECTIVES: Cold-induced vasodilation is a local mechanism of protection against frostbite in non-injured persons. We assessed whether an increase in skin blood flow (SkBF) during local cooling (LC) was observed in individuals with spinal cord injuries (SCIs) and if the response patterns differed between region levels or sites. SETTING: Laboratory of Wakayama Medical University and the affiliated clinics, Japan. METHODS: A local cooler device (diameter 4 cm) was placed on the chest (sensate) and right thigh (non-sensate) in persons with cervical (SCIC; n = 9) and thoracolumbar SCIs (SCITL; n = 9). After the surface temperature under the device was controlled at 33 °C for 10 min (baseline), LC (-0.045 °C/s) was applied and the skin temperature was maintained at 15 and 8 °C for 15 min of each stage. SkBF (laser Doppler flowmetry) was monitored using a 1-mm needle-type probe inserted into its center. RESULTS: The percent change in SkBF (%ΔSkBF) on the chest remained unchanged until the end of 15 °C stage; thereafter, it increased to a level at least 70% greater than the baseline during the 8 °C stage in both groups. The %ΔSkBF on the thigh in both SCIC and SCITL notably increased from 8 and 6 min respectively, during the 8°C stage, compared to 1 min before the stage; however, it did not exceed the baseline level. CONCLUSIONS: An increase in SkBF during LC was observed both in the sensate and non-sensate areas in SCIs, although the magnitude was larger in the sensate area.

Effect of wet clothing removal on skin temperature in subjects exposed to cold and wrapped in a vapor barrier: a human, randomized, crossover field study.

BACKGROUND: Prehospital care for cold-stressed and hypothermic patients focuses on effective insulation and rewarming. When encountering patients wearing wet clothing, rescuers can either remove the wet clothing before isolating the patient or isolate the patient using a vapor barrier. Wet clothing removal increases skin exposure but avoids the need to heat the wet clothing during rewarming. Leaving wet clothing on will avoid skin exposure but is likely to increase heat loss during rewarming. This study aimed to evaluate the effect of wet clothing removal compared to containing the moisture using a vapor barrier on skin temperature in a prehospital setting. METHODS: This randomized crossover experimental field study was conducted in a snow cave in Hemsedal, Norway. After an initial cooling phase of 30 min while wearing wet clothes, the participants were subjected to one of two rewarming scenarios: (1) wet clothing removal and wrapping in a vapor barrier, insulating blankets, and windproof outer shell (dry group) or (2) wrapping in a vapor barrier, insulating blankets, and windproof outer shell (wet group). The mean skin temperature was the primary outcome whereas subjective scores for both thermal comfort and degree of shivering were secondary outcomes. Primary outcome data were analyzed using the analysis of covariance (ANCOVA). RESULTS: After an initial decrease in temperature during the exposure phase, the dry group had a higher mean skin temperature compared to the wet group after only 2 min. The skin-rewarming rate was highest in the initial rewarming stages for both groups, but increased in the dry group as compared to the wet group in the first 10 min. Return to baseline temperature occurred significantly faster in the dry group (mean 12.5 min [dry] vs. 28.1 min [wet]). No intergroup differences in the subjective thermal comfort or shivering were observed. CONCLUSION: Removal of wet clothing in combination with a vapor barrier increases skin rewarming rate compared to encasing the wet clothing in a vapor barrier, in mild cold and environments without wind. TRIAL REGISTRATION: ClinicalTrials.gov ID NCT05996757, retrospectively registered 18/08/2023.

Skin temperature of the knee was effectively reduced when using a new continuous cold-flow cryocompression device: a randomised controlled crossover trial.

OBJECTIVE: To determine which temperature settings on a new continuous cold-flow cryocompression device effectively reduce knee skin temperature to 10-15 °C, where pain and swelling are expected to be attenuated. DESIGN: Randomised controlled crossover trial. SETTING: University laboratory. PARTICIPANTS: 32 healthy adult participants recruited (1 dropout) with no contraindications to cryocompressive therapy. INTERVENTION: A k-type thermocouple was used to record skin temperature at baseline and every five minutes during a 30-minute cryocompression treatment in a control condition and when using four different device temperature settings (6 °C, 8 °C, 10 °C, and 12 °C) on a continuous cold-flow cryocompression device. Conditions were labelled Control, Con-6, Con-8, Con-10, and Con-12, respectively. MAIN OUTCOME MEASURES: Skin temperature change (°C) throughout cryocompression; time taken (mins) to achieve skin temperature < 15 °C; and the difference between final skin temperature and device temperature setting (°C). RESULTS: Median (IQR) skin temperature after cryocompression was 32.1 °C (29.3-33.4), 12.8 °C (12.1-14.6), 14.3 °C (13.8-15.7), 16.1 °C (15.2-17.3), and 17.7 °C (16.9-18.9) for the Control condition and Con-6, Con-8, Con-10 and Con-12, respectively. It took 20 min (Con-6) and 25 min (Con-8) for skin temperature to reach < 15 °C. A median (IQR) difference of 6.8 °C (6.1-8.6), 6.3 °C (5.8-7.7), 6.1 °C (5.2-7.3), and 5.7 °C (4.9-6.9) for Con-6, Con-8, Con-10, and Con-12, respectively was observed between device temperature setting and final skin temperature. CONCLUSIONS: The device is recommended as it reduced skin temperature to the therapeutic range of 10-15 °C during a 30-minute treatment when using the 6 °C or 8 °C device temperature settings. Future research should determine optimal treatment lengths for cryocompression. CONTRIBUTION OF THE PAPER.

A new noninvasive technique for heat-flux-based deep body thermometry together with possible estimation of thermal resistance of the skin tissue.

A new noninvasive core-thermometry technique, based on the use of two heat flux sensors with different very low thermal resistances, is proposed. Thermodynamically derived equations, using a pair of skin temperatures and heat fluxes detected from the sensors, can give the estimated deep body temperature (DBT) together with thermal resistance of the skin tissue itself. The validity and accuracy of this method are firstly investigated through in vitro experiments using a tissue phantom model and, secondly, as in vivo comparisons with sublingual (Tsub) or rectal temperature (Trec) measurements in 9 volunteers, attaching the sensors around the upper sternum or the nape. Model experiments showed a good agreement between the measured and estimated temperatures, ranging from approximately 36 to 42 ℃. In vivo experiments demonstrated linear correlations between the estimated DBT and both Tsub and Trec values, though the estimated DBT was 0.13 ℃ higher than Tsub and 0.42 ℃ lower than Trec on average. The results also strongly suggested the possibility to estimate the tissue thermal resistance; this is discussed herein. Although further in vivo experiments under various environmental conditions are necessary, this method appears highly promising as an accurate, useful and convenient core-thermometry system for medical and healthcare settings.

A randomised crossover trial of five cryocompression devices' ability to reduce skin temperature of the knee.

BACKGROUND: The application of cold and pressure to the knee is a common part of post-operative rehabilitation. Skin temperature should be reduced to within 10-15 °C to optimise the therapeutic benefits of cryocompression. The purpose of this study was to investigate the ability of five different cryocompression devices to reduce skin temperature to within this therapeutic range. MATERIALS AND METHODS: 32 healthy adult participants (mean (SD): age 26.3 (7.9) years; BMI 24.8 (2.7) kg/m2; 20 males) were recruited for this randomised crossover study. Skin temperature was measured 20 mm distal to the patella using a k-type thermocouple every five minutes during a 30-minute treatment with one of five different cryocompression devices (Physiolab S1, GameReady, Cryo/Cuff, VPulse, and a Gel Wrap). Changes in skin temperature over time were compared to baseline within and between conditions. A subjective rating of comfort was also recorded for each device. RESULTS: The Physiolab S1 and GameReady devices caused significantly lower skin temperatures compared to the VPulse, Gel Wrap, and Cryo/Cuff after 30 minutes (p<0.05). 87-96% reported a positive comfort rating for the Physiolab S1, VPulse, Cryo/Cuff and Gel Wrap, whereas 53% of participants reported a positive comfort rating for the GameReady. CONCLUSIONS: Only the Physiolab S1 and GameReady devices reduced skin temperature of the knee to within the target range of 10-15 °C. The Physiolab S1 was reportedly more comfortable than the GameReady. Clinicians should be aware of the performance differences of different cryocompression devices to understand which is most likely to provide an effective dose of cold therapy to a joint.

Response of skin temperature, blood ammonia and lactate during incremental exercise until exhaustion in elite athletes.

The study aimed to evaluate the lower limb skin temperature (Tsk) and blood concentrations of lactate (LA) and ammonia (NH3) during exercise and recovery. Eleven elite sprint athletes (25 ± 3.4 yrs) and 11 elite endurance athletes (24.45 ± 5.4 yrs) performed an incremental running test until exhaustion. Body composition was estimated using the DXA method. Thermograms of the anterior and posterior surfaces of the lower limbs were recorded at rest, before each test stage (every 3 min, starting from 10 km h-1 and increasing by 2 km h-1), and in the 5th, 10th, 15th, 20th, and 30th minute of recovery. Endurance athletes had a higher maximum oxygen uptake than sprint athletes (5.0 ± 0.7 vs 4.3 ± 0.4 l·kg-1, p = 0.018), lower percentage of lean content (79 ± 2 vs 83 ± 2%, p < 0.001), and a higher percentage of fat content in the lower limbs (17 ± 2 vs 12 ± 2%, p < 0.001). In both groups, a significant decrease in Tsk was observed compared to resting value (endurance athletes-31.5 ± 0.6 °C; sprint athletes-32.3 ± 0.6 °C), during exercise (p < 0.001) and rewarming during recovery (p < 0.001). However, endurance athletes had a lower Tsk than sprint athletes at the exhaustion point (30.0 ± 1.1 vs 31.6 ± 0.8 °C, p < 0.05) and the pattern of change in Tsk differed between groups (p < 0.001). Tsk in the endurance athletes group decreased throughout the exercise protocol and returned more rapidly to initial values during recovery, while Tsk in the sprint group stabilised between moderate intensity and exhaustion, recovering more slowly after exercise. Both LA (endurance athletes-max 10.2 ± 1.5; sprint athletes-max 10.1 ± 1.4 mmol⋅L-1, p < 0.001) and NH3 (endurance athletes-max 75.6 ± 11.5; sprint athletes-max 76.7 ± 9.0 mmol⋅L-1, p < 0.001) increased during exercise and decreased during recovery (p < 0.001). During exercise, lower levels and slower increases in LA were observed during exercise in the endurance athletes' group (p < 0.05). A negative correlation was revealed between Tsk and fat percentage (r = -0.43 to -0.71, p < 0.05). Tsk was positively correlated with LA during recovery (r = 0.43 to 0.48, p < 0.05), and negatively during recovery (r = -0.45 to -0.54, p < 0.05). Differences between groups in maximum aerobic capacity, the pattern of change in Tsk, and the correlation between Tsk and LA suggest that individuals who decrease less Tsk during exercise and higher Tsk during recovery are those with better aerobic capacity. In addition, athletes with less body fat dissipate heat from their tissues more efficiently.

The effect of exposure to cold on dexterity and temperature of the skin and hands.

Objectives. This study aimed to determine the impact of low temperature (-1 °C, +5 °C) on manual dexterity and hand skin temperature after 1 h of exposure when using two types of protective gloves. Methods. Ten male participants wore double gloves or single gloves, when spending 1 h in a climatic chamber at -1, +5 or +20 °C. Before and after the cold exposure, measurements of mean weighted body skin temperature, hand skin temperature, the Purdue Pegboard Test and hand grip strength were performed. Results. There were statistically significant differences in the values of mean weighted body skin temperature and left and right hand skin temperature between the study variants. Conclusion. No effect of cold exposure (-1 °C, +5 °C) on manual dexterity was observed, but there was an effect of -1 °C temperature change on weighted mean skin temperature and hand skin temperature during 1 h of exposure. The decrease in both right and left hand skin temperature after cold exposure was the largest for -1 °C while using single gloves, and differed significantly from the other variants.

Investigating intestinal mast cell dynamics during acute heat stress in growing pigs.

Objectives were to examine the temporal pattern of intestinal mast cell dynamics and the effects of a mast cell stabilizer (ketotifen [Ket]) during acute heat stress (HS) in growing pigs. Crossbred barrows (n = 42; 32.3 ±â€…1.9 kg body weight [BW]) were randomly assigned to 1 of 7 environmental-therapeutic treatments: (1) thermoneutral (TN) control (TNCon; n = 6), (2) 2 h HS control (2 h HSCon; n = 6), (3) 2 h HS + Ket (2 h HSKet; n = 6); (4) 6 h HSCon (n = 6), (5) 6 h HSKet (n = 6), (6) 12 h HSCon (n = 6), or (7) 12 h HSKet (n = 6). Following 5 d of acclimation to individual pens, pigs were enrolled in two experimental periods (P). During P1 (3 d), pigs were housed in TN conditions (21.5 ±â€…0.8 °C) for the collection of baseline measurements. During P2, TNCon pigs remained in TN conditions for 12 h, while HS pigs were exposed to constant HS (38.1 ±â€…0.2 °C) for either 2, 6, or 12 h. Pigs were euthanized at the end of P2, and blood and tissue samples were collected. Regardless of time or therapeutic treatment, pigs exposed to HS had increased rectal temperature, skin temperature, and respiration rate compared to their TNCon counterparts (1.9 °C, 6.9° C, and 119 breaths/min; P < 0.01). As expected, feed intake and BW gain markedly decreased in HS pigs relative to their TNCon counterparts (P < 0.01). Irrespective of therapeutic treatment, circulating corticotropin-releasing factor decreased from 2 to 12 h of HS relative to TNCon pigs (P < 0.01). Blood cortisol increased at 2 h of HS (2-fold; P = 0.04) and returned to baseline by 6 h. Plasma histamine (a proxy of mast cell activation) remained similar across thermal treatments and was not affected by Ket administration (P > 0.54). Independent of Ket or time, HS increased mast cell numbers in the jejunum (94%; P < 0.01); however, no effects of HS on mast cell numbers were detected in the ileum or colon. Jejunum and ileum myeloperoxidase area remained similar among treatments (P > 0.58) but it tended to increase (12%; P = 0.08) in the colon in HSCon relative to TNCon pigs. Circulating lymphocytes and basophils decreased in HSKet relative to TN and HSCon pigs (P ≤ 0.06). Blood monocytes and eosinophils were reduced in HS pigs relative to their TNCon counterparts (P < 0.01). In summary, HS increased jejunum mast cell numbers and altered leukocyte dynamics and proinflammatory biomarkers. However, Ket administration had no effects on mast cell dynamics measured herein.

Heat stress (HS) affects various physiological, metabolic, and endocrine parameters, ostensibly due to reduced intestinal barrier integrity and the ensuing immune response. Evidence indicates that generalized "stress" may be a critical component of HS-induced leaky gut, a mechanism likely mediated by mast cells. Mast cell activation has been extensively associated with various stress-related intestinal inflammatory conditions; however, its contribution to intestinal barrier dysfunction during HS remains unclear. Thus, this study was designed to evaluate mast cell dynamics during an acute HS challenge and to assess the effects a mast cell stabilizer on biomarkers of intestinal inflammation. Herein, HS induced a rapid increase in circulating cortisol, increased jejunum mast cell numbers, and altered metabolism, leukocyte dynamics, and proinflammatory biomarkers. Contrary to our hypothesis, HS did not alter circulating histamine (a biomarker of mast cell activation), and mast cell stabilization did not affect mast cell numbers nor altered histamine concentrations. Altogether, our observations support a connection between HS and intestinal mast cell infiltration that may contribute to the pathophysiology of intestinal dysfunction during a heat load.

Pressure Injury Mitigation in Prolonged Care: A Randomized Noninferiority and Superiority Trial.

INTRODUCTION: Combat casualties are at increased risk for pressure injuries (PIs) during prolonged casualty care. There is limited research on operational PI risk mitigation strategies. The purpose of this study was to (1) compare a prototype mattress (AirSupport) designed for operational conditions versus the foldable Talon litter and Warrior Evacuation Litter Pad (WELP) on PI risk factors and (2) determine whether the Talon + AirSupport pad was noninferior and superior to the Talon + WELP on skin interface pressure. MATERIALS AND METHODS: Healthy adults (N = 85; 20 men and 65 women), aged 18 to 55 years, were stratified based on body fat percentage and randomized into three groups: Talon (n = 15), Talon + AirSupport (n = 35), and Talon + WELP (n = 35). The participants were asked to lie in a supine position for 1 hour. The outcomes included skin interface pressure (body surface areas: Sacrum, buttocks, occiput, and heels), sacral and buttock skin temperature and moisture, and discomfort and pressure. The study was approved by the University of Washington Institutional Review Board. RESULTS: Aim 1: The Talon had significantly higher peak skin interface pressure versus the AirSupport and WELP on the sacrum, buttocks, occiput, and heels. Skin temperature increase over the 1-hour loaded period was significantly lower on Talon versus AirSupport or WELP, reflecting a lower temperature-induced ischemic load. There was no significant difference in skin moisture changes or discomfort between the surfaces. Aim 2: The upper confidence limits for the difference in skin interface pressure (all body surface areas) for AirSupport versus WELP were below 25 mm Hg, establishing noninferiority of the AirSupport to the WELP. AirSupport was also superior to WELP for the peak interface pressure on the sacrum, occiput, and heels but not on the buttocks. Skin temperature changes (sacrum or buttocks) were not significantly different between the AirSupport and WELP. CONCLUSIONS: The Talon litter presents a PI risk because of increased skin interface pressure, and hence, immediate action is warranted. The decreased PI risk associated with the lower skin interface pressures on the AirSupport and WELP was offset by the higher skin temperature, which may add the equivalent of 20 to 30 mm Hg pressure to the ischemic burden. Thus, any pressure redistribution intervention must be evaluated with a consideration for skin interface pressure, temperature, and moisture. Data from this study were applied to a predictive model for skin damage. Under operational conditions where resources and the environment may limit patient repositioning, it would be expected that casualties would suffer skin damage within 2 to 5 hours, with the occiput as the highest risk area. The severity of predicted skin damage is lowest on the AirSupport, which is consistent with the noninferiority and superiority of the AirSupport mattress compared to the WELP and Talon. Operational utility: The AirSupport and WELP, which were both superior to the Talon, are operationally feasible solutions to mitigate PI risk. The smaller size of the Talon (2.7 kgs compressible) versus the WELP (5 kgs noncompressible) may make them appropriate for different levels of the operational setting.