ClimApp-Integrating Personal Factors with Weather Forecasts for Individualised Warning and Guidance on Thermal Stress.

This paper describes the functional development of the ClimApp tool (available for free on iOS and Android devices), which combines current and 24 h weather forecasting with individual information to offer personalised guidance related to thermal exposure. Heat and cold stress assessments are based on ISO standards and thermal models where environmental settings and personal factors are integrated into the ClimApp index ranging from -4 (extremely cold) to +4 (extremely hot), while a range of -1 and +1 signifies low thermal stress. Advice for individuals or for groups is available, and the user can customise the model input according to their personal situation, including activity level, clothing, body characteristics, heat acclimatisation, indoor or outdoor situation, and geographical location. ClimApp output consists of a weather summary, a brief assessment of the thermal situation, and a thermal stress warning. Advice is provided via infographics and text depending on the user profile. ClimApp is available in 10 languages: English, Danish, Dutch, Swedish, Norwegian, Hellenic (Greek), Italian, German, Spanish and French. The tool also includes a research functionality providing a platform for worker and citizen science projects to collect individual data on physical thermal strain and the experienced thermal strain. The application may therefore improve the translation of heat and cold risk assessments and guidance for subpopulations. ClimApp provides the framework for personalising and downscaling weather reports, alerts and advice at the personal level, based on GPS location and adjustable input of individual factors.

The (in)dependency of blood and sweat sodium, chloride, potassium, ammonia, lactate and glucose concentrations during submaximal exercise.

PURPOSE: To reduce the need for invasive and expensive measures of human biomarkers, sweat is becoming increasingly popular in use as an alternative to blood. Therefore, the (in)dependency of blood and sweat composition has to be explored. METHODS: In an environmental chamber (33 °C, 65% relative humidity; RH), 12 participants completed three subsequent 20-min cycling stages to elicit three different local sweat rates (LSR) while aiming to limit changes in blood composition: at 60% of their maximum heart rate (HRmax), 70% HRmax and 80% HRmax, with 5 min of seated-rest in between. Sweat was collected from the arm and back during each stage and post-exercise. Blood was drawn from a superficial antecubital vein in the middle of each stage. Concentrations of sodium, chloride, potassium, ammonia, lactate and glucose were determined in blood plasma and sweat. RESULTS: With increasing exercise intensity, LSR, sweat sodium, chloride and glucose concentrations increased (P ≤ 0.026), while simultaneously limited changes in blood composition were elicited for these components (P ≥ 0.093). Sweat potassium, lactate and ammonia concentrations decreased (P ≤ 0.006), while blood potassium decreased (P = 0.003), and blood ammonia and lactate concentrations increased with higher exercise intensities (P = 0.005; P = 0.007, respectively). The vast majority of correlations between blood and sweat parameters were non-significant (P > 0.05), with few exceptions. CONCLUSION: The data suggest that sweat composition is at least partly independent of blood composition. This has important consequences when targeting sweat as non-invasive alternative for blood measurements.

Two isothermal challenges yield comparable physiological and subjective responses.

PURPOSE: Ventilated vests are developed to reduce thermal stress by enhancing convective and evaporative cooling from skin tissue underneath the vest. The purpose of this study is to investigate whether thermal stress is equal when a ventilated vest is worn compared to a no-vest situation with similar dry thermal resistance. METHODS: Nine healthy males walked on a treadmill (7 km h-1) for 45 min in a desert climate (34 °C, 20% relative humidity) with and without ventilated vest. Gastrointestinal temperature (Tgi), heart rate (HR), and skin temperature (Tsk) were continuously monitored. Local sweat rate (LSR) was assessed two times on six skin locations. Subjective ratings were assessed every 10 min. RESULTS: Final Tgi (37.6 ± 0.1 °C for vest and 37.6 ± 0.1 °C for no-vest), HR (133 ± 7 bpm and 133 ± 9 bpm) and mean Tsk (34.8 ± 0.7 °C and 34.9 ± 0.6 °C) were not different between conditions (p ≥ 0.163). Scapula skin temperature (Tscapula) under the vest tended to be lower (baseline to final: ΔTscapula = 0.35 ± 0.37 °C) than without vest (ΔTscapula = 0.74 ± 0.62 °C, p = 0.096). LSR at locations outside the vest did not differ with and without vest (p ≥ 0.271). Likewise, subjective responses did not differ between conditions (χ2 ≥ 0.143). CONCLUSIONS: We conclude that two systems with similar dry thermal resistance and, therefore, similar required evaporation, resulted in similar thermal stress during paced walking in a hot-dry environment. Local ventilation did not alter the sweating response on locations outside the vest.

Hyperoxia enhances self-paced exercise performance to a greater extent in cool than hot conditions.

NEW FINDINGS: What is the central question of this study? Hyperoxia enhances endurance performance by increasing O2 availability to locomotor muscles. We investigated whether hyperoxia can also improve prolonged self-paced exercise in conditions of elevated thermal and cardiovascular strain. What is the main finding and its importance? Hyperoxia improved self-paced exercise performance in hot and cool conditions. However, the extent of the improvement (increased work rate relative to normoxia) was greater in cool conditions. This suggests that the development of thermal and cardiovascular strain during prolonged self-paced exercise under heat stress might attenuate the hyperoxia-mediated increase in O2 delivery to locomotor muscles. ABSTRACT: The aim of this study was to determine whether breathing hyperoxic gas when self-paced exercise performance is impaired under heat stress enhances power output. Nine well-trained male cyclists performed four 40 min cycling time trials: two at 18°C (COOL) and two at 35°C (HOT). For the first 30 min, participants breathed ambient air, and for the remaining 10 min normoxic (fraction of inspired O2 0.21; NOR) or hyperoxic (fraction of inspired O2 0.45; HYPER) air. During the first 30 min of the time trials, power output was lower in the HOT (∼250 W) compared with COOL (∼273 W) conditions (P < 0.05). In the final 10 min, power output was higher in HOT-HYPER (264 ± 25 W) than in HOT-NOR (244 ± 31 W; P = 0.008) and in COOL-HYPER (315 ± 28 W) than in COOL-NOR (284 ± 25 W; P < 0.001). The increase in absolute power output in COOL-HYPER was greater than in HOT-HYPER (∼12 W; P = 0.057), as was normalized power output (∼30%; P < 0.001). The peripheral capillary percentage oxygen saturation increased in HOT-HYPER and COOL-HYPER (P < 0.05), with COOL-HYPER being higher than HOT-HYPER (P < 0.01). Heart rate was higher during the HOT compared with COOL trials (P < 0.01), as were mean skin temperature (P < 0.001) and peak rectal temperature (HOT, ∼39.5°C and COOL, ∼38.9°C; P < 0.01). Thermal discomfort was also higher in the HOT compared with COOL (P < 0.01), whereas ratings of perceived exertion were similar (P > 0.05). Hyperoxia enhanced performance during the final 25% of a 40 min time trial in both HOT and COOL conditions compared with normoxia. However, the attenuated increase in absolute and normalized power output noted in the HOT condition suggests that heat stress might mitigate the influence of hyperoxia.

Relation between finger cold-induced vasodilation and rewarming speed after cold exposure.

PURPOSE: The risk for local cold injuries has been linked to poor cold-induced vasodilation (CIVD) during cold exposure and to poor rewarming after cold exposure. The purpose of this study is to establish the relation between CIVD and rewarming speed. METHODS: Twelve participants immersed one hand in ice water for 30 min to evoke CIVD and the other hand in ice water for 10 min to investigate the rewarming profile. The ring, middle and index fingertip temperatures were monitored during hand immersion and the resistance index of frostbite (RIF) was calculated. RIF depends on minimal (Tmin) and mean (Tmean) finger skin temperature and onset time. Rewarming was quantified using an infrared imaging system and the rewarming speed over 19 min was determined. RESULTS: Tmin (5.8 ± 3.0 °C) and Tmean (10.4 ± 3.0 °C) caused non-distinctive contributions to the total RIF-scores so that onset time (12.7 ± 3.1 min) became the dominant factor. A significant negative correlation between RIF and rewarming speed was found (rs = - 0.60, p = 0.041). CONCLUSIONS: The negative relation between RIF and rewarming speed may be explained by the common observation that onset time relates to the temperature of fingertip tissue, while Tmin, Tmean and rewarming speed relates to body thermal status. The rewarming test is to be preferred over the CIVD test in terms of ease of use, but the predictive value of the rewarming test for cold injuries is limited, cannot replace the RIF since onset time of finger vasodilation is not included and should be further investigated.

Comparison of two telemetric intestinal temperature devices with rectal temperature during exercise.

OBJECTIVE: The discomfort caused by rectal probes and esophageal probes for the estimation of body core temperature has triggered the development of gastrointestinal (GI) capsules that are easily accepted by athletes and workers due to their non-invasive characteristics. We compare two new GI capsule devices with rectal temperature during cycle ergometer exercise and rest. APPROACH: Eight participants followed a protocol of (i) 30 min exercise with a power output of 130 W, (ii) 5 min rest, (iii) 10 min self-paced maximum exercise, and (iv) 15 min rest. Core temperature was measured using two GI-capsule devices (e-Celsius and myTemp) and rectal temperature. MAIN RESULTS: The myTemp system provided only slightly different temperatures to the rectal temperature probe during rest and exercise. However, the factory-calibrated e-Celsius system showed a systematic rectal temperature underestimation of 0.2 °C that is corrected in the 2018 versions. Both GI capsules reacted faster to temperature changes in the body compared to the rectal temperature probe during the rest period following maximum exercise. SIGNIFICANCE: The GI-capsules react faster to temperature changes in the body compared to the rectal temperature probe, in particular during the rest period following exercise.

Optimal bus temperature for thermal comfort during a cool day.

A challenge for electric buses is to minimize heating and cooling power to maximally extend the driving range, but still provide sufficient thermal comfort for the driver and passengers. Therefore, we investigated the thermal sensation (TS) and thermal comfort (TC) of passengers in buses during a cool day (temperature 13.4 ± 0.5 °C, relative humidity (RH) 60 ± 5.8%) typical for the Dutch temperate maritime climate. 28 Males and 72 females rated TS and TC and gave information on age, stature, body weight and worn garments. The temperature in the bus of 22.5 ± 1.1 °C and RH of 59.9 ± 5.8% corresponded to a slightly warm feeling (TS = 0.85 ± 1.06) and TC of 0.39 ± 0.65. TS related significantly to bus temperature, clothing insulation and age. Linear regression based on these parameters showed that the temperature in the bus corresponding to TC = 0 and TS = 0 would have been 20.9 ± 0.6 °C. In conclusion, a 1.6 °C lower bus temperature during the investigated cool day probably would have led to less thermal discomfort and energy savings of electrical busses. The methodology to relate climatic measurements to subjective assessments is currently employed in a wider climatic range and may prove to be useful to find a better balance between thermal comfort and energy savings of the bus.

Quantification of continual anthropogenic pollutants released in swimming pools.

Disinfection in swimming pools is often performed by chlorination, However, anthropogenic pollutants from swimmers will react with chlorine and form disinfection by-products (DBPs). DBPs are unwanted from a health point of view, because some are irritating, while others might be carcinogenic. The reduction of anthropogenic pollutants will lead to a reduction in DBPs. This paper investigates the continual release of anthropogenic pollutants by means of controlled sweat experiments in a pool tank during laboratory time-series experiments (LTS experiments) and also during on-site experiments (OS experiments) in a swimming pool. The sweat released during the OS and LTS experiments was very similar. The sweat rate found was 0.1-0.2 L/m(2)/h at water temperatures below 29 °C and increased linearly with increasing water temperatures to 0.8 L/m(2)/h at 35 °C. The continual anthropogenic pollutant release (CAPR) not only consisted of sweat, particles (mainly skin fragments and hair) and micro-organisms, but also sebum (skin lipids) has to be considered. The release of most components can be explained by the composition of sweat. The average release during 30 min of exercise is 250 mg/bather non-purgeable organic carbon (NPOC), 77.3 mg/bather total nitrogen (TN), 37.1 mg/bather urea and 10.1 mg/bather ammonium. The release of NPOC cannot be explained by the composition of sweat and is most probably a result of sebum release. The average release of other components was 1.31 × 10(9) # particles/bather (2-50 µm), 5.2 µg/bather intracellular adenosine triphosphate (cATP) and 9.3 × 10(6) intact cell count/bather (iCC). The pool water temperature was the main parameter to restrain the CAPR. This study showed that a significant amount of the total anthropogenic pollutants release is due to unhygienic behaviour of bathers.

Cold-induced vasodilatation in cold-intolerant rats after nerve injury.

PURPOSE: Cold-induced vasodilatation (CIVD) is a cyclic regulation of blood flow during prolonged cooling of protruding body parts. It is generally considered to be a protective mechanism against local cold injuries and cold intolerance after peripheral nerve injury. The aim of this study was to determine the role of the sympathetic system in initiating a CIVD response. METHODS: Eight rats were operated according to the spared nerve injury (SNI) model, eight underwent a complete sciatic lesion (CSL) and six underwent a sham operation. Prior to operation, 3, 6 and 9 weeks postoperatively, both hind limbs were cooled and the skin temperature was recorded to evaluate the presence of CIVD reactions. Cold intolerance was determined using the cold plate test and mechanical hypersensitivity measured using the Von Frey test. RESULTS: No significant difference in CIVD was found comparing the lateral operated hind limb for time (preoperatively and 3, 6 and 9 weeks postoperatively; p = 0.397) and for group (SNI, CSL and Sham; p = 0.695). SNI and CSL rats developed cold intolerance and mechanical hypersensitivity. CONCLUSION: Our data show that the underlying mechanisms that initiate a CIVD reaction are not affected by damage to a peripheral nerve that includes the sympathetic fibres. We conclude that the sympathetic system does not play a major role in the initiation of CIVD in the hind limb of a rat. CLINICAL RELEVANCE: No substantial changes in the CIVD reaction after peripheral nerve injury imply that the origin of cold intolerance after a traumatic nerve injury is initiated by local factors and has a more neurological cause. This is an important finding for future developing treatments for this common problem, as treatment focussing on vaso-regulation may not help diminish symptoms of cold-intolerant patients.

Effects of wind application on thermal perception and self-paced performance.

Physiological and perceptual effects of wind cooling are often intertwined and have scarcely been studied in self-paced exercise. Therefore, we aimed to investigate (1) the independent perceptual effect of wind cooling and its impact on performance and (2) the responses to temporary wind cooling during self-paced exercise. Ten male subjects completed four trials involving 15 min standardized incremental intensity cycling, followed by a 15-km self-paced cycling time trial. Three trials were performed in different climates inducing equivalent thermal strain: hot humid with wind (WIND) and warm humid (HUMID) and hot dry (DRY) without wind. The fourth trial (W3-12) was equal to HUMID, except that wind cooling was unexpectedly provided during kilometers 3-12. Physiological, perceptual and performance parameters were measured. Subjects felt generally cooler during the WIND than the HUMID and DRY trials, despite similar heart rate, rectal and skin temperatures and a WBGT of ~4 °C higher. The cooler thermal sensation was not reflected in differences in thermal comfort or performance. Comparing W3-12 to HUMID, skin temperature was 1.47 ± 0.43 °C lower during the wind interval, leading to more favorable ratings of perceived exertion, thermal sensation and thermal comfort. Overall, power output was higher in the W3-12 than the HUMID-trial (256 ± 29 vs. 246 ± 22 W), leading to a 67 ± 48 s faster finish time. In conclusion, during self-paced exercise in the heat, wind provides immediate and constant benefits in physiological strain, thermal perception and performance. Independent of physiological changes, wind still provides a greater sensation of coolness, but does not impact thermal comfort or performance.

Effect of warm-up and precooling on pacing during a 15-km cycling time trial in the heat.

PURPOSE: The best way to apply precooling for endurance exercise in the heat is still unclear. The authors analyzed the effect of different preparation regimens on pacing during a 15-km cycling time trial in the heat. METHODS: Ten male subjects completed four 15-km time trials (30°C), preceded by different preparation regimes: 10 min cycling (WARM-UP), 30 min scalp cooling of which 10 min was cycling (SC+WARM-UP), ice-slurry ingestion (ICE), and ice slurry ingestion + 30 min scalp cooling (SC+ICE). RESULTS: No differences were observed in finish time and mean power output, although power output was lower for WARM-UP than for SC+ICE during km 13-14 (17 ± 16 and 19 ± 14 W, respectively) and for ICE during km 13 (16 ± 16 W). Rectal temperature at the start of the time trial was lower for both ICE conditions (~36.7°C) than both WARMUP conditions (~37.1°C) and remained lower during the first part of the trial. Skin temperature and thermal sensation were lower at the start for SC+ICE. CONCLUSIONS: The preparation regimen providing the lowest body-heat content and sensation of coolness at the start (SC+ICE) was most beneficial for pacing during the latter stages of the time trial, although overall performance did not differ.

Volunteer kinematics and reaction in lateral emergency maneuver tests.

It is important to understand human kinematics and muscle activation patterns in emergency maneuvers for the design of safety systems and for the further development of human models. The objective of this study was to quantify kinematic behavior and muscle activation in simulated steering tests in several realistic conditions. In total 108 tests were performed with 10 volunteers undergoing purely lateral maneuvers at 5 m/s^2 deceleration or simulated lane change maneuvers at 5 m/s^2 peak acceleration and peak yaw velocity of 25 °/s. Test subjects were seated on a rigid seat and restrained by a 4-point belt with retractor. Driver subjects were instructed to be relaxed or braced and to hold the steering wheel while passenger subjects were instructed to put their hands on their thighs. Subjects were instrumented with photo markers that were tracked with 3D high- speed stereo cameras and with electromyography (EMG) electrodes on 8 muscles. Corridors of head displacement, pitch and roll and displacement of T1, shoulder, elbow, hand and knee were created representing mean response and standard deviation of all subjects. In lane change tests for the passenger configuration significant differences were observed in mean peak of head left lateral displacement between the relaxed and the braced volunteers, i.e. 171 mm (σ=58, n=21) versus 121 mm (σ=46, n=17), respectively. Sitting in a relaxed position led to significantly lower muscle activity of the neck muscles. It was concluded that significantly more upper body motion and lower muscle activity was observed for relaxed subjects than for braced subjects.

Telemetry pill versus rectal and esophageal temperature during extreme rates of exercise-induced core temperature change.

Core temperature measurement with an ingestible telemetry pill has been scarcely investigated during extreme rates of temperature change, induced by short high-intensity exercise in the heat. Therefore, nine participants performed a protocol of rest, (sub)maximal cycling and recovery at 30 °C. The pill temperature (T(pill)) was compared with the rectal temperature (T(re)) and esophageal temperature (T(es)). T(pill) corresponded well to T(re) during the entire trial, but deviated considerably from T(es) during the exercise and recovery periods. During maximal exercise, the average ΔT(pill)-T(re) and ΔT(pill)-T(es) were 0.13 ± 0.26 and -0.57 ± 0.53 °C, respectively. The response time from the start of exercise, the rate of change during exercise and the peak temperature were similar for T(pill) and T(re.) T(es) responded 5 min earlier, increased more than twice as fast and its peak value was 0.42 ± 0.46 °C higher than T(pill). In conclusion, also during considerable temperature changes at a very high rate, T(pill) is still a representative of T(re). The extent of the deviation in the pattern and peak values between T(pill) and T(es) (up to >1 °C) strengthens the assumption that T(pill) is unsuited to evaluate central blood temperature when body temperatures change rapidly.

Optimising the acquisition and retention of heat acclimation.

Heat acclimation (HA) often starts in a moderately hot environment to prevent thermal overload and stops immediately prior to athletic activities. The aims of this study were (1) to establish whether acclimation to a moderately hot climate is sufficient to provide full acclimation for extreme heat and (2) to investigate the physiological responses to heat stress during the HA decay period. 15 male subjects exercised for 9 consecutive days at 26° C Wet Bulb Globe Temperature (WBGT) and 3 days at 32° C WBGT on a cycle ergometer for up to 2 h per day and repeated the exercise 3, 7 and 18 days later in 26° C WBGT. Rectal temperature (T (re)) and heart rate (HR) were measured during 60 min of steady state exercise (∼45% of maximum oxygen uptake). During days 1-9, end-exercise T (re) was reduced from 38.7±0.1 to a plateau of 38.2±0.1° C (p<0.05), HR was reduced from 156±10 to 131±11 bpm (p<0.05). No changes in HR and T (re) occurred during the 3 days in the very hot environment. However, T (re) during rest and exercise were significantly lower by 0.4-0.5° C after HA compared with day 9, suggesting that heat acclimation did not decay but resulted in further favourable adaptations.

Limitations of temperature measurement in the aural canal with an ear mould integrated sensor.

Aural canal temperature measurement using an ear mould integrated sensor (T(ac)) might be a method suited for continuous non-invasive core temperature estimation in operational settings. We studied the effect of ambient temperature, wind and high intensity exercise on T(ac) and its ability to predict esophageal (T(es)) and rectal temperatures (T(re)). Seven subjects performed a protocol of rest at 21, 10 and 30 °C, followed by exercise and recovery at 30 °C. The subjects performed the protocol twice: with and without face-wind from halfway through the 30 °C rest period. Extra auricle insulation was applied at one side. Ambient temperature changes affected T(ac) significantly, while T(es) and T(re) remained stable. Insulating the auricle reduced but did not abolish this effect. Wind had an immediate cooling effect on T(ac) independent of auricle insulation. During exercise and recovery in 30 °C, T(ac) provided acceptable group predictions of T(re) in trials without wind (bias: -0.66 ± 0.21 °C covered, -1.20 ± 0.15 °C uncovered). Bias was considerably higher with wind, but variability was similar (-1.73 ± 0.11 °C covered, -2.49 ± 0.04 °C uncovered). Individual predictions of T(es) and T(re) showed more variation, especially with wind. We conclude that T(ac) may be used for core temperature assessment of groups in warm and stable conditions.

Non-invasive continuous core temperature measurement by zero heat flux.

Reliable continuous core temperature measurement is of major importance for monitoring patients. The zero heat flux method (ZHF) can potentially fulfil the requirements of non-invasiveness, reliability and short delay time that current measurement methods lack. The purpose of this study was to determine the performance of a new ZHF device on the forehead regarding these issues. Seven healthy subjects performed a protocol of 10 min rest, 30 min submaximal exercise (average temperature increase about 1.5 °C) and 10 min passive recovery in ambient conditions of 35 °C and 50% relative humidity. ZHF temperature (T(zhf)) was compared to oesophageal (T(es)) and rectal (T(re)) temperature. ΔT(zhf)-T(es) had an average bias ± standard deviation of 0.17 ± 0.19 °C in rest, -0.05 ± 0.18 °C during exercise and -0.01 ± 0.20 °C during recovery, the latter two being not significant. The 95% limits of agreement ranged from -0.40 to 0.40 °C and T(zhf) had hardly any delay compared to T(es). T(re) showed a substantial delay and deviation from T(es) when core temperature changed rapidly. Results indicate that the studied ZHF sensor tracks T(es) very well in hot and stable ambient conditions and may be a promising alternative for reliable non-invasive continuous core temperature measurement in hospital.

Infrared thermal imaging of the inner canthus of the eye as an estimator of body core temperature.

Several studies suggest that the temperature of the inner canthus of the eye (T(ca)), determined with infrared thermal imaging, is an appropriate method for core temperature estimation in mass screening of fever. However, these studies used the error prone tympanic temperature as a reference. Therefore, we compared T(ca) to oesophageal temperature (T(es)) as gold standard in 10 subjects during four conditions: rest, exercise, recovery and passive heating. T(ca) and T(es) differed significantly during all conditions (mean ΔT(es) - T(ca) 1.80 ±â€Š0.89°C) and their relationship was inconsistent between conditions. Also within the rest condition alone, intersubject variability was too large for a reliable estimation of core temperature. This poses doubts on the use of T(ca) as a technique for core temperature estimation, although generalization of these results to fever detection should be verified experimentally using febrile patients.

How to measure thermal effects of personal cooling systems: human, thermal manikin and human simulator study.

Thermal effects, such as cooling power and thermophysiological responses initiated upon application of a personal cooling system, can be assessed with (i) humans, (ii) a thermal manikin and (iii) a thermophysiological human simulator. In order to compare these methods, a cooling shirt (mild cooling) and an ice vest (strong cooling) were measured using human participants and a thermal manikin. Under all conditions, cooling was provided for 45 min, while resting at a room temperature of 24.6-25.0 degrees C and a relative humidity of 22-24%. Subsequently, the thermophysiological human simulator was used under the same conditions to provide data on thermophysiological responses such as skin and rectal temperatures. The cooling power determined using the thermal manikin was 2 times higher for the cooling shirt and 1.5 times higher for the ice vest compared to the cooling power determined using human participants. For the thermophysiological human simulator, the cooling power of the cooling shirt was similar to that obtained using human participants. However, it was 2 times lower for the ice vest when using the thermophysiological human simulator. The thermophysiological human simulator is shown to be a useful tool to predict thermophysiological responses, especially upon application of mild cooling intensity. However, the thermophysiological human simulator needs to be further improved for strong cooling intensities under heterogeneous conditions.

Digital rewarming patterns after median and ulnar nerve injury.

PURPOSE: Posttraumatic cold intolerance (CI) is a frequent and important sequel after peripheral nerve injury. In this study, it is hypothesized that altered rewarming patterns after peripheral nerve injury are related to the degree of posttraumatic CI. This hypothesis is tested by quantitatively comparing rewarming patterns of the digits in controls and in median or ulnar nerve injury patients and by investigating relationships between rewarming patterns, sensory recovery, and CI. METHODS: Twelve median or ulnar nerve injury patients with a follow-up of 4 to 76 months after nerve repair and 13 control subjects had isolated cold stress testing of the hands. Video thermography was used to analyze and compare rewarming patterns of the injured and uninjured digits after cold stress testing. Temperature curves were analyzed by calculating the Q value as an indicator of heat transfer (temperature added during the first 10 minutes after start of active rewarming) and the maximum slope. RESULTS: Test-retest reliability was 0.64 and 0.79, respectively, for the Q value and maximum slope. High Q values and maximum slopes were interpreted as the presence of active rewarming. Patients with return of active rewarming had better sensory recovery and lower Blond McIndoe Cold Intolerance Severity Scale (CISS) scores. Better sensory recovery was correlated with lower CISS scores. CONCLUSIONS: Test-retest reliability of cold stress testing was good, and we found a difference in rewarming patterns between nerve injury patients and controls. The presence of active rewarming in the nerve injury patients was related to sensory recovery and fewer complaints of posttraumatic CI.

Cold intolerance following median and ulnar nerve injuries: prognosis and predictors.

This study describes the predictors for cold intolerance and the relationship to sensory recovery after median and ulnar nerve injuries. The study population consisted of 107 patients 2 to 10 years after median, ulnar or combined median and ulnar nerve injuries. Patients were asked to fill out the Cold Intolerance Severity Score (CISS) questionnaire and sensory recovery was measured using Semmes-Weinstein monofilaments. Fifty-six percent of the patients with a single nerve injury and 70% with a combined nerve injury suffered abnormal cold intolerance. Patients with no return of sensation had dramatically higher CISS-scores than patients with normal sensory recovery. Females had higher CISS scores post-injury than males. Cold intolerance did not diminish over the years. Patients with higher CISS scores needed more time to return to their work. Age, additional arterial injury, site or type of the injury and dominance of the hand were not found to have a significant influence on cold intolerance.