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Purpose The main aims of this study were to describe the effects of incontinence pad composition on skin wetness, the skin/pad microclimate, and skin barrier function. We also evaluated the potential utility of our methods for future clinical investigation of absorbent pad design. Design Single-blind, quasi-experimental, open cohort design. Subjects and setting Twenty healthy older volunteers (mean age = 72.8 years, SD = 5.8 years; 8 male and 12 female) tested 2 absorbent pad types, with acquisition layers of different compositions (A and B) applied to different sites on the volar aspect of the forearms. One type A pad served as control (A dry) versus 3 pad samples wetted with 3 volumes of saline (A 15 mL, A 35 mL, and B 15 mL). The study was conducted within the clinical laboratory of a university nursing research group in the United Kingdom. Methods Skin barrier function was assessed by measuring transepidermal water loss (TEWL), stratum corneum (SC) hydration by corneometry, and skin surface pH using a standard skin pH electrode. Skin water loading (excess water penetration into the skin) was quantified by measuring TEWL and creating a desorption curve of the water vapor flux density. Calculating the area under the curve of the desorption curve to give skin surface water loss reflected excess water penetration into the skin. In a subgroup of the sample, the temperature and relative humidity (microclimate) at the interface between the skin and test pads were measured using a wafer-thin sensor placed between the skin and pad sample. Proinflammatory cytokine release from the SC was assessed using a noninvasive lipophilic film. The main outcome measures in this study were the differences in biophysical measurements of skin barrier function (TEWL, corneometer, and pH) before and after the application of the different pads. Results Mean ± SD baseline TEWL across all test sites was 10.4 ± 4.4 g/h/m. This increased to 10.6 ± 3.8 g/h/m at the control site, 15.3 ± 6.3 g/h/m for the A 15-mL pad, 15.3 ± 3.9 g/h/m for the A 35-mL pad, and 15.6 ± 3.2 g/h/m for the B 15-mL pad. The mean baseline skin surface pH was 5.9 ± 0.04; cutaneous pH increased to a mean of 6.1 ± 0.06 following all pad applications (P = .16). Mean SC hydration remained unchanged at the control site (A dry). In contrast, SC hydration increased following the application of all wetted pads. Target cytokines were detected in all samples we analyzed. The IL-1RA/IL-1α ratio increased following pad application, except for the wettest pad. Conclusion Study findings suggest that absorbent pad design and composition, particularly the acquisition layer, affect performance and may influence skin health. Based on our experience with this study, we believe the methods we used provide a simple and objective means to evaluate product performance that could be used to guide the future development of products and applied to clinical settings.

The human body has dedicated receptors for sensing temperature and touch, but not wetness. How then is wetness perceived? To test if wetness perception arises from the sensory integration of touch and temperature, and to quantify its measurement in humans, we designed a wetness perception monitor (WPM) which enabled variation of temperature at the fingertips of participants while measuring the pressure exerted on a test surface in the controlled environment of a moisture-free chamber. Thirty randomly selected adults (18+ years) were tested for their perception of dampness/wetness using the WPM. Our data suggest that humans perceive dampness and wetness at average temperatures of 22 ± 0.4°C and 18 ± 0.5°C, respectively, and these sensations are extinguished at temperatures below 16 ± 1°C. Measurements were obtained at an average tactile pressure of 1.5 ± 0.3 kPa. Young adults (18–35 years) sensed wetness at significantly higher temperatures than middle-aged adults (36–55 years) or mature adults (56+ years), who sensed wetness at similar temperatures. We found a surprising sex difference in wetness perception, with females sensing wetness at higher temperatures than males. When the data were screened for outliers, we found that participants whose readings were outside normal ranges, self-reported sensory deficits suggesting that wetness perception could potentially be used as a noninvasive biomarker.

New findings What is the central question of this study? Ageing impairs the skin's thermal and tactile sensitivity: does ageing also induce loss of skin wetness sensitivity? What is the main finding and its importance? Older adults show an average 15% loss of skin wetness sensitivity, with this sensory deficit being mediated by a combination of reductions in skin's tactile sensing and hydration status. These findings increase knowledge of wetness sensing mechanisms across the lifespan. Abstract Humans use sensory integration mechanisms to sense skin wetness based on thermal and mechanical cues. Ageing impairs the skin's thermal and tactile sensitivity, yet we lack evidence on whether wetness sensing also changes with ageing. We mapped local skin wetness and temperature sensitivity in response to cold-, neutral- and warm-wet stimuli applied to the forehead, neck, lower back, dorsal foot, index finger and thumb, in 10 Younger (22.4 ± 1.1 years) and 10 Older (58.2 ± 5.1 years) males. We measured local skin temperature and conductance (i.e., a marker of hydration status) at the tested sites, to establish the role of skin's thermal and mechanical parameters in ageing-induced changes in wetness sensing. Irrespective of body site, Older reported overall lower wetness perceptions than Younger across all wet-stimulus temperatures (mean difference: -14.6 mm; 95% CI: -4.3, -24.9; P = 0.008; ∼15% difference). When considering regional wetness sensitivity, the effect of ageing was more pronounced in response to the cold-wet stimulus over the lover back (mean difference Older vs. Younger: -36.8 mm; 95% CI: -68.4, -5.2; P = 0.014; ∼37% difference) and dorsal foot (mean difference: -37.1 mm; 95% CI: -68.7, -5.5; P = 0.013; ∼37% difference). We found no differences between age groups on overall thermal sensations (P = 0.744) nor local skin temperature (P = 0.372); however, we found that Older presented overall lower skin conductance than Younger (mean difference: -1.56 μS; 95% CI: -0.49, -2.62; P = 0.005), which corresponded to an ∼78% reduction in skin hydration. We conclude that skin wetness sensing decreases with ageing primarily due to age-induced changes in skin mechanics and tactile sensitivity.

Humans often experience wet stimuli using their hands, yet we know little on how sensitive our fingers are to wetness and the mechanisms underlying this sensory function. We therefore aimed to quantify the minimum amount of water required to detect wetness on the human index fingerpad, the wetness detection threshold, and assess its modulation by temperature. Eight blinded participants (24.0 ± 5.2 y; 23.3 ± 3.5 BMI) used their index fingerpad to statically touch stimuli varying in volume (0, 10, 20, 30, 40 or 50 ml) and temperature (25, 29, 33 or 37 °C). During and post contact, participants rated wetness and thermal sensations using a modified yes/no task and a visual analogue scale. The wetness detection threshold at a moisture temperature akin to human skin (33 °C) was 24.7 ± 3.2ml. This threshold shifted depending on moisture temperature (P = 0.002), with cooler temperatures reducing (18.7 ± 3.9ml at 29 °C) and warmer temperatures increasing (27.0 ± 3.0ml at 37 °C) thresholds. When normalised over contact area, the wetness detection threshold at 33 °C corresponded to 1.926x10-4 ml mm-2 (95% CI: 1.873x10-4, 1.979x10-4 ml mm-2). Threshold differences were reflected by magnitude estimation data, which were analysed using linear regression to show that both volume and moisture temperature can predict magnitude estimations of wetness (P < 0.001). Our results indicate high sensitivity to wetness in the human index fingerpad, which can be modulated by moisture temperature. These findings are relevant for the design of products with wetness management properties.

KEY POINTS Skin wetness occurring secondary to the build-up of sweat on the skin provokes thermal discomfort, the precursor to engaging in cool-seeking behaviour. Associative evidence indicates that skin wetness stimulates cool-seeking behaviour to a greater extent than increases in core and mean skin temperatures. The independent contribution of skin wetness to cool-seeking behaviour during heat stress has never been established. We demonstrate that skin wetness augments cool-seeking behaviour during passive heat stress independently of differential increases in skin temperature and core temperature. We also identify that perceptions of skin wetness were not elevated despite increases in actual skin wetness. These data support the proposition that afferent signalling from skin wetness enhances the desire to engage in cool-seeking behaviour during passive heat stress. ABSTRACT This study tested the hypothesis that elevations in skin wetness augments cool-seeking behaviour during passive heat stress. Twelve subjects (6 females, age: 24 ± 2 y) donned a water-perfused suit circulating 34 °C water and completed two trials resting supine in a 28.5 ± 0.4 °C environment. The trials involved a 20 min baseline period (26 ± 3% relative humidity (RH)), 60 min while ambient humidity was maintained at 26±3% RH (LOW) or increased to 67 ± 5% RH (HIGH), followed by 60 min passive heat stress (HS) where the water temperature in the suit was incrementally increased to 50 °C. Subjects were able to seek cooling when their neck was thermally uncomfortable by pressing a button. Each button press initiated 30 s of -20 °C fluid perfusing through a custom-made device secured against the skin on the dorsal neck. Mean skin (Tskin ) and core (Tcore ) temperatures, mean skin wetness (Wskin ) and neck device temperature (Tdevice ) were measured continuously. Cool-seeking behaviour was determined from total time receiving cooling (TTcool ) and cumulative button presses. Tskin and Tcore increased during HS (P

To investigate the effect of heat, moisture transfer, and mechanical tactile properties of fabrics on skin wetness perception when fabrics were in dynamic contact with skin at three velocities, nine knitted fabrics varying in fiber composition, thickness, and surface texture were evaluated by 20 participants using a wetness rating scale. The objective physical properties of the fabrics, namely, heat and moisture transfer and surface texture, and human physiological responses, namely, skin cooling rate and myoelectric signals, under various conditions were measured, and their correlations with the subjective wetness perception were studied. While the results indicated a significant influence of fabric type, water content, and velocity on skin wetness perception, no significant relation between electromyography and wetness perception was found. Fabrics with faster water spreading speeds and lower absorption rates were perceived as less wet, and the maximum transient thermal flow and skin cooling rate had a significant positive correlation with wetness perception. Furthermore, subjective wetness perception was predicted by the physical parameters of the fabric, that is, maximum transient thermal flow, water content, and friction coefficient, with an acceptable goodness of fit ( R2 = 0.82, p

Key points: Humans lack skin receptors for wetness (i.e. hygroreceptors), yet we present a remarkable wetness sensitivity. Afferent inputs from skin cold-sensitive thermoreceptors are key for sensing wetness; yet, it is unknown whether males and females differ in their wetness sensitivity across their body and whether high intensity exercise modulates this sensitivity. We mapped sensitivity to cold, neutral and warm wetness across five body regions and show that females are more sensitive to skin wetness than males, and that this difference is greater for cold than warm wetness sensitivity. We also show that a single bout of maximal exercise reduced the sensitivity to skin wetness (i.e. hygro-hypoesthesia) of both sexes as a result of concurrent decreases in thermal sensitivity. These novel findings clarify the physiological mechanisms underpinning this fundamental human sensory experience. In addition, they indicate sex differences in thermoregulatory responses and will inform the design of more effective sport and protective clothing, as well as thermoregulatory models. Abstract: Humans lack skin hygroreceptors and we rely on integrating cold and tactile inputs from A-type skin nerve fibres to sense wetness. Yet, it is unknown whether sex and exercise independently modulate skin wetness sensitivity across the body. We mapped local sensitivity to cold, neutral and warm wetness of the forehead, neck, underarm, lower back and dorsal foot in 10males (27.8±2.7years; 1.92±0.1m2 body surface area) and 10 females (25.4±3.9years; 1.68±0.1m2 body surface area), at rest and post maximal incremental running. Participants underwent our quantitative sensory test where they reported the magnitude of thermal and wetness perceptions (visual analogue scale) resulting from the application of a cold (5°C below skin temperature) wet (0.8mL of water), neutral wet and warm wet (5°C above skin temperature) thermal probe (1.32cm2) to five skin sites. We found that: (i) females were ∼14% to ∼17% more sensitive to cold-wetness than males, yet both sexes were as sensitive to neutral- and warm-wetness; (ii) regional differences were present for cold-wetness only, and these followed a craniocaudal increase that was more pronounced in males (i.e. the foot was ∼31% more sensitive than the forehead); and (iii) maximal exercise reduced cold-wetness sensitivity over specific regions in males (i.e. ∼40% decrease in foot sensitivity), and also induced a generalized reduction in warm-wetness sensitivity in both sexes (i.e. ∼4% to ∼6%). For the first time, we show that females are more sensitive to cold wetness than males and that maximal exercise induce hygro-hypoesthesia. These novel findings expand our knowledge on sex differences in thermoregulatory physiology.

Sweating efficiency (SE) is essential for evaluating heat strain. The dripping of sweat off the skin surface of a nude subject occurs locally at an area where the secreted sweat exceeds the local evaporative capacity. However, in clothed subjects, “dripping” sweat is absorbed by clothing. In the present paper, the cooling efficiency of the sweating of a clothed subject is analyzed in relation to SE. First, typical patterns for the regional distribution of the sweat rate (SR) and the capacity of evaporation (CE) of a nude subject were introduced, and the dripping sweat rate was derived as a surplus of the SR over the CE; an equation of SE was derived from combinations of the two typical SR patterns and the uniform CE pattern. Then, the values of SE were calculated numerically, and the results were found to be approximately equal to those obtained experimentally by Alber–Wallerström & Holmér and theoretically from the equation of 1 − 0.5wsw 2 used in ISO7933. Based on these results, the SE was improved by arranging the distribution of the CE by controlling air velocities over the body surface. Further, the improved SE was found to contribute to the heat strain alleviation of clothed subjects., We analytically estimated the sweating efficiency of humans based on the surplus of the regional sweat rate over the regional capacity of evaporation. We improved the sweating efficiency by exposing the higher air velocity to the trunk area and proved its effect on heat strain alleviation of a clothed subject by predicting the mean skin temperature.

Undoubtedly, adjusting our thermoregulatory behavior represents the most effective mechanism to maintain thermal homeostasis and ensure survival in the diverse thermal environments that we face on this planet. Remarkably, our thermal behavior is entirely dependent on the ability to detect variations in our internal (i.e., body) and external environment, via sensing changes in skin temperature and wetness. In the past 30 years, we have seen a significant expansion of our understanding of the molecular, neuroanatomical, and neurophysiological mechanisms that allow humans to sense temperature and humidity. The discovery of temperature-activated ion channels which gate the generation of action potentials in thermosensitive neurons, along with the characterization of the spino-thalamo-cortical thermosensory pathway, and the development of neural models for the perception of skin wetness, are only some of the recent advances which have provided incredible insights on how biophysical changes in skin temperature and wetness are transduced into those neural signals which constitute the physiological substrate of skin thermal and wetness sensations. Understanding how afferent thermal inputs are integrated and how these contribute to behavioral and autonomic thermoregulatory responses under normal brain function is critical to determine how these mechanisms are disrupted in those neurological conditions, which see the concurrent presence of afferent thermosensory abnormalities and efferent thermoregulatory dysfunctions. Furthermore, advancing the knowledge on skin thermal and wetness sensations is crucial to support the development of neuroprosthetics. In light of the aforementioned text, this review will focus on the peripheral and central neurophysiological mechanisms underpinning skin thermal and wetness sensations in humans. © 2016 American Physiological Society. Compr Physiol 6:1279-1294, 2016.2016.

Purpose. To investigate the effect of cold stimulation (contacting wet fabric) and tactile stimulation (dynamic friction) on skin wetness perception: (a) wetness perception of fabric with different...

International audience; Our perception of skin wetness is generated readily, yet humans have no known receptor (hygroreceptor) to signal this directly. It is easy to imagine the sensation of water running over our hands or the feel of rain on our skin. The synthetic sensation of wetness is thought to be produced from a combination of specific skin thermal and tactile inputs, registered through thermoreceptors and mechanoreceptors, respectively. The present review explores how thermal and tactile afference from the periphery can generate the percept of wetness centrally. We propose that the main signals include information about skin cooling, signaled primarily by thinly myelinated thermoreceptors, and rapid changes in touch, through fast-conducting, myelinated mechanoreceptors. Potential central sites for integration of these signals, and thus the perception of skin wetness, include the primary and secondary somatosensory cortices and the insula cortex. The interactions underlying these processes can also be modeled to aid in understanding and engineering the mechanisms. Furthermore, we discuss the role that sensing wetness could play in precision grip and the dexterous manipulation of objects. We expand on these lines of inquiry to the application of the knowledge in designing and creating skin sensory feedback in prosthetics. The addition of real-time, complex sensory signals would mark a significant advance in the use and incorporation of prosthetic body parts for amputees in everyday life

Sensing skin wetness is linked to inputs arising from cutaneous cold-sensitive afferents. As thermosensitivity to cold varies significantly across the torso, we investigated whether similar regional differences in wetness perception exist. We also investigated the regional differences in thermal pleasantness and whether these sensory patterns are influenced by ambient temperature. Sixteen males (20 ± 2 yr) underwent a quantitative sensory test under thermo-neutral [air temperature (Tair) = 22°C; relative humidity (RH) = 50%] and warm conditions (Tair = 33°C; RH = 50%). Twelve regions of the torso were stimulated with a dry thermal probe (25 cm2) with a temperature of 15°C below local skin temperature (Tsk). Variations in Tsk, thermal, wetness, and pleasantness sensations were recorded. As a result of the same cold-dry stimulus, the skin-cooling response varied significantly by location ( P = 0.003). The lateral chest showed the greatest cooling (−5 ± 0.4°C), whereas the lower back showed the smallest (−1.9 ± 0.4°C). Thermal sensations varied significantly by location and independently from regional variations in skin cooling with colder sensations reported on the lateral abdomen and lower back. Similarly, the frequency of perceived skin wetness was significantly greater on the lateral and lower back as opposed to the medial chest. Overall wetness perception was slightly higher under warm conditions. Significantly more unpleasant sensations were recorded when the lateral abdomen and lateral and lower back were stimulated. We conclude that humans present regional differences in skin wetness perception across the torso, with a pattern similar to the regional differences in thermosensitivity to cold. These findings indicate the presence of a heterogeneous distribution of cold-sensitive thermo-afferent information.

Although the ability to sense skin wetness and humidity is critical for behavioral and autonomic adaptations, humans are not provided with specific skin receptors for sensing wetness. It has been proposed that we “learn” to perceive the wetness experienced when the skin is in contact with a wet surface or when sweat is produced through a multisensory integration of thermal and tactile inputs generated by the interaction between skin and moisture. However, the individual roles of thermal and tactile cues and how these are integrated peripherally and centrally by our nervous system is still poorly understood. Here we tested the hypothesis that the central integration of coldness and mechanosensation, as subserved by peripheral A-nerve afferents, might be the primary neural process underpinning human wetness sensitivity. During a quantitative sensory test, we found that individuals perceived warm-wet and neutral-wet stimuli as significantly less wet than cold-wet stimuli, although these were characterized by the same moisture content. Also, when cutaneous cold and tactile sensitivity was diminished by a selective reduction in the activity of A-nerve afferents, wetness perception was significantly reduced. Based on a concept of perceptual learning and Bayesian perceptual inference, we developed the first neurophysiological model of cutaneous wetness sensitivity centered on the multisensory integration of cold-sensitive and mechanosensitive skin afferents. Our results provide evidence for the existence of a specific information processing model that underpins the neural representation of a typical wet stimulus. These findings contribute to explaining how humans sense warm, neutral, and cold skin wetness.

Background/purpose: In the absence of humidity receptors in human skin, the perception of skin wetness is considered a somatosensory experience resulting from the integration of temperature (particularly cold) and mechanical inputs. However, limited data are available on the role of the temperature sense. Methods: Wet and dry stimuli at 4 and 8°C above local skin temperature were applied on the back of 7 participants (age 21± 2 years) while skin temperature and conductance, thermal and wetness perceptions were recorded. Results: Resting local skin temperature always increased by the application of the stimuli (+0.5 to +1.4°C). No effect of stimulus wetness was found on wetness perceptions (p>0.05). The threshold (point “-2 slightly wet” on the wetness scale) to identify a clearly perceived wetness was never reached during any stimulations and participants did not perceive that some of the stimuli were wet. Overall, warm temperature stimuli suppressed the perception of skin wetness. Conclusions: We conclude that it is not the contact of the skin with moisture per se, but rather the integration of particular sensory inputs (amongst which coldness seems dominant) which drives the perception of skin wetness during the initial contact with a wet surface.

The central integration of thermal (i.e. cold) and mechanical (i.e. pressure) sensory afferents is suggested as to underpin the perception of skin wetness. However, the role of temperature and mechanical inputs, and their interaction, is still unclear. Also, it is unknown whether this intra-sensory interaction changes according to the activity performed or the environmental conditions. Hence, we investigated the role of peripheral cold afferents, and their interaction with tactile afferents, in the perception of local skin wetness during rest and exercise in thermo-neutral and warm environments. Six cold-dry stimuli, characterized by decreasing temperatures [i.e. -4, -8 and -15 °C below the local skin temperature (T(sk))] and by different mechanical pressures [i.e. low pressure (LP): 7 kPa; high pressure (HP): 10 kPa], were applied on the back of 8 female participants (age 21 ± 1 years), while they were resting or cycling in 22 or 33 °C ambient temperature. Mean and local Tsk, thermal and wetness perceptions were recorded during the tests. Cold-dry stimuli produced drops in Tsk with cooling rates in a range of 0.06-0.4 °C/s. Colder stimuli resulted in increasing coldness and in stimuli being significantly more often perceived as wet, particularly when producing skin cooling rates of 0.18 °C/s and 0.35 °C/s. However, when stimuli were applied with HP, local wetness perceptions were significantly attenuated. Wetter perceptions were recorded during exercise in the warm environment. We conclude that thermal inputs from peripheral cutaneous afferents are critical in characterizing the perception of local skin wetness. However, the role of these inputs might be modulated by an intra-sensory interaction with the tactile afferents. These findings indicate that human sensory integration is remarkably multimodal.

Cold sensations are suggested as the primary inducer of the perception of skin wetness. However, limited data are available on the effects of skin cooling. Hence, we investigated the role of peripheral cold afferents in the perception of wetness. Six cold-dry stimuli (producing skin cooling rates in a range of 0.02 to 0.41°C/s) were applied on the forearm of 9 female participants. Skin temperature and conductance, thermal and wetness perception were recorded. Five out of 9 participants perceived wetness as a result of cold-dry stimuli with cooling rates in a range of 0.14 to 0.41°C/s, while 4 did not perceive skin wetness at all. Although skin cooling and cold sensations play a role in evoking the perception of wetness, these are not always of a primary importance and other sensory modalities (i.e. touch and vision), as well as the inter-individual variability in thermal sensitivity, might be equally determinant in characterising this perception.

Relevance of local skin wettedness (w (local)) to general thermal comfort while wearing clothing was investigated in eight males. In the experiments, skin wettedness of the whole body (w (body)) was controlled to be around the thermal comfort limit, while w (local) in different target locations of equal area (anterior and dorsal torso, arms, and thighs) was pushed beyond the comfort limit using special test garments. Subjects walked on a treadmill at 4.5 km h(-1) under 22 degrees C 50% RH. Arms and thighs were thermally in discomfort when their w (local) exceeded 0.32. On the other hand, discomfort in the anterior and dorsal torso was initiated when their w (local) arrived at 0.42 and 0.45. That is, the relation of the local comfort limit with w (local) differed depending upon the location. It was observed; however, that general discomfort was not induced when w (body) remained below 0.36 even if w (local) was higher than its local comfort limit.

Background/purpose: Excessive skin hydration from occlusive coverings such as absorbent articles, bandages, etc. has been known to compromise the skin's barrier properties. Damage to the stratum corneum occurs from prolonged exposure to wetness and limited product breathability, which reduces evaporation. Protection from wetness may be imparted by barrier materials, such as lotions and ointments on the skin. Barrier materials are traditionally applied by hand from bulk containers (bottle or tube). In recent years, diapers have been made that contain barrier ointments designed to transfer to the skin during wear. The purpose of this research was to develop a reliable in vivo method for evaluating skin wetness protection when using personal products. Method: The means for evaluating wetness protection in vivo is dye exclusion evaluation on human skin. Dye exclusion involves application of a barrier material, followed by dye application and skin staining evaluation. The dye exclusion method may be conducted on adult forearms with direct application of the barrier material or on infant or adult torsos after wearing a diaper or incontinence product (or other personal products) that contains the barrier material. Dye exclusion on infants used cosmetic dyes (safe for use in the eye area). Results: Dye exclusion demonstrated skin protection on both adult forearms and on infant buttocks. Ointments in diapers protected the skin from the dye when diapers were worn from a few hours to several days (with appropriate changes of product). Conclusion: The dye exclusion method was able to demonstrate the advantage of barrier ointments for wetness protection and also to discriminate between ointment formulations.

Humans sense the wetness of a wet surface through the somatosensory integration of thermal and tactile inputs generated by the interaction between skin and moisture. However, little is known on how wetness is sensed when moisture is produced via sweating. We tested the hypothesis that, in the absence of skin cooling, intermittent tactile cues, as coded by low-threshold skin mechanoreceptors, modulate the perception of sweat-induced skin wetness, independently of the level of physical wetness. Ten males (22 yr old) performed an incremental exercise protocol during two trials designed to induce the same physical skin wetness but to induce lower (TIGHT-FIT) and higher (LOOSE-FIT) wetness perception. In the TIGHT-FIT, a tight-fitting clothing ensemble limited intermittent skin-sweat-clothing tactile interactions. In the LOOSE-FIT, a loose-fitting ensemble allowed free skin-sweat-clothing interactions. Heart rate, core and skin temperature, galvanic skin conductance (GSC), and physical ( wbody) and perceived skin wetness were recorded. Exercise-induced sweat production and physical wetness increased significantly [GSC: 3.1 μS, SD 0.3 to 18.8 μS, SD 1.3, P < 0.01; wbody: 0.26 no-dimension units (nd), SD 0.02, to 0.92 nd, SD 0.01, P < 0.01], with no differences between TIGHT-FIT and LOOSE-FIT ( P > 0.05). However, the limited intermittent tactile inputs generated by the TIGHT-FIT ensemble reduced significantly whole-body and regional wetness perception ( P < 0.01). This reduction was more pronounced when between 40 and 80% of the body was covered in sweat. We conclude that the central integration of intermittent mechanical interactions between skin, sweat, and clothing, as coded by low-threshold skin mechanoreceptors, significantly contributes to the ability to sense sweat-induced skin wetness.

Objective Pressure ulcers often occur at sites subjected to pressure and wetness. Although skin wetness is a risk factor for pressure ulcers,the mechanisms and effects of wetness versus urine constituents on skin breakdown is unclear. The hypothesis that wetness reduces skin hardness and, thereby, increases vulnerability of underlying blood vessels to pressure-induced flow reductions was tested in this study. Design Pads saturated with water and with a water solution mixed with the main chemical constituents of urine (synthetic urine; s-urine) were applied to forearm skin of 10 healthy subjects for 5.5 hours. Skin hardness, blood flow change caused by 60 mm Hg of pressure, erythema, and temperature were compared among dry, water, and s-urine test sites. Participants 10 healthy women. Setting Research Center, Nova Southeastern University, Health Professions Division, Fort Lauderdale, FL. Main results S-urine and water caused significant reductions in initial hardness and caused greater initial perfusion decreases during pressure load when compared with dry sites. Skin temperature and erythema were lower at wet sites when compared with dry sites. Conclusions The findings of this study are consistent with the concept that sustained skin wetness increases vulnerability to pressure-induced blood flow reduction. The effect appears to be mainly dependent on wetness, but urine constituents may exacerbate the effect. In addition, wetness-related skin cooling may play a role. In the healthy subjects studied, the blood flow decrease was not sustained due to perfusion recovery under pressure. Skin wetness would likely have more sustained effects in patients with compromised recovery mechanisms. Measures to diminish skin exposure to wetness in these patients, whatever the wetness source, are an important consideration in a multifaceted strategy to reduce the risk of pressure ulcers.

Human skin is innervated with a variety of receptors serving somatosensation and includes the sensory sub-modalities of touch, temperature, pain and itch. The density and type of receptors differ across the body surface, and there are various body-map representations in the brain. The perceptions of skin sensations outside of the specified sub-modalities, e.g. wetness or greasiness, are described as 'touch blends' and are learned. The perception of wetness is generated from the coincident activation of tactile and thermal receptors. The present study aims to quantify threshold levels of wetness perception and find out if this differs across body sites. A rotary tactile stimulator was used to apply a moving, wetted stimulus over selected body sites at a precise force and velocity. Four wetness levels were tested over eight body sites. After each stimulus, the participant rated how wet the stimulus was perceived to be using a visual analogue scale. The results indicated that participants discriminated between levels of wetness as distinct percepts. Significant differences were found between all levels of wetness, apart from the lowest levels of comparison (20 μl and 40 μl). The perception of wetness did not, however, differ significantly across body sites and there were no significant interactions between wetness level and body site. The present study emphasizes the importance of understanding how bottom-up and top-down processes interact to generate complex perceptions.

Skin wetness is proportional to diaper wetness, and with increased skin wetness, the potential for diaper dermatitis is increased. This study evaluated a wide range of infant diaper products. Eighty healthy volunteers wore 2-inch wetted diaper patches on their volar forearm for two hours. An evaporimeter was used to measure excess skin wetness attributed to the patches. The amount of moisture retained in the patch was also calculated. We found that superabsorbent (SA) disposable diapers kept the skin drier and retained more synthetic urine than cloth reusable and conventional disposable brands, and thus have the greatest potential for helping prevent diaper dermatitis. The SA brands evaluated did an equally adequate job in keeping the skin dry and in retaining moisture. Conventional disposable diapers were less able to keep the skin dry than SA diapers and were not superior to cloth products in most instances. Cloth diapers” performance depended on their composition. Those with several layers of the same fabric were less successful in keeping the skin dry than ones that contained middle layers of different nonwoven components.

During the 1990s, emphasis on the health and safety of people who exercise in hot, humid conditions increased and many organizations became aware of the need for protection against heat-related disorders. A practical, pre-cooling strategy applicable to several sporting codes, which is low cost, easy to use, light-weight and which enhances cooling of the human body prior to and following exercise, was developed and tested. Eight males and eight females participated in a maximal oxygen consumption (VO2max) test and four trials: a control (without cooling) and wearing each of three different cooling vests (A, B, C). Vests were worn during the rest, stretch, warm-up (50% VO2max) and recovery stages of the protocol, but not during the 30 min run (70% VO2max). Core and skin temperatures during exercise were reduced (by approximately 0.5 degrees C, rectal; 0.1-1.4 degrees C, abdominal skin temperature) and sweat rates were lower (by approximately 10-23%). Endurance times for running at 95% of VO2max were increased by up to 49 s. Perceptions of the thermal state and skin wetness showed changes to greater levels of satisfaction. Physiological and sensory responses were related to design features of the vests.

The strength of the association between diaper dermatitis and measurements of skin wetness and skin pH was evaluated by statistical analysis of four diaper trials involving 1601 infants. Although the strength of the association between skin wetness and diaper dermatitis was greater than that between skin pH and diaper dermatitis, increases in wetness and pH were both significantly associated with elevated mean grades for diaper dermatitis. The skin environment least likely to be associated with diaper dermatitis is one In which Increases In both skin wetness and skin pH are minimized.

In a skilled nursing facility, 36 patients (chiefly elderly) with persistent urinary incontinence were the subjects of this study. In their management, the usual disposable pads were compared with a new launderable bed sheet (Kylie) which absorbs urine in the second layer while maintaining a dry surface next to the patient's skin. There was a 42 percent reduction in the frequency of bedding changes with the new bed sheets. The patients experienced increased comfort due to decreased skin wetness and decreased creasing of the sheets. The reduced frequency of bed linen changes permitted longer undisturbed periods for the patient. Management costs were reduced by 40 percent with the launderable bed sheets. There were no adverse effects on the condition of the patients or in the quality of care.

Wearing dry and wet cloth and disposable diaper materials has certain effects on the degree of skin wetness. These, in turn, affect the coefficient of skin friction, the skin's susceptibility to abrasion damage, its permeability, and its support of microbial growth. These effects were explored using an adult model wearing forearm patches. The adult model was validated by comparisons of skin wetness and friction values for infants and adults determined under similar conditions. Skin wetness was proportional to diaper wetness. With increased skin wetness, there were increased coefficients of friction and increased abrasion damage, skin permeability, and microbial growth. Cloth diaper material produced wetter skin than did disposable diaper material at equivalent loadings.

Diaper dermatitis results from the action of a number of physical and chemical factors on the skin. While its etiology is complex, there is agreement that prolonged contact between wet diapers and the skin leading to excessive hydration of the stratum corneum and reduced barrier function is a primary factor. Recent research also indicates that pH elevation resulting from ammonia production increases the probability of skin damage due to fecal enzyme activity. New diapers containing absorbent polymers blended with cellulose fluff in the absorbent core have been developed. The absorbent polymer binds fluids and controls pH in the diaper environment. To assess the effectiveness of these diapers, a clinical study was conducted with approximately 150 infants over 15 weeks, using fluff diapers and absorbent polymer diapers. The results clearly showed that the diapers with absorbent polymer provide a better skin environment than those with fluff only with respect to lower skin wetness and pH control (instrumental measurements). In addition, the clinicians' grades indicated a directional reduction in diaper rash severity.