Title : Measuring transepidermal water loss: Tewameter?, vapometer?, h4500?, and battery-free sensors?
Abstract:
Background: Tewameter?, Vapometer?, H4500?, and battery free NFC sensors are effective in measuring TEWL and each may be preferential instrument for different indications.
Purpose: Compare current alliteration on four such instruments, and identify which has been documented for use during measurement of a specific physiological indication.
Methods: Compiled 20 recent publications that narrowed to those exploring the specific TEWL instrument specific condition. Search engines and 1-2 word phrases were used to identify such studies.
Results: Tewameter depicted TEWL decreases while scars healed and appears an efficient TEWL tool in this compromised skin. VapoMeter appears reliable for measuring hyperhidrosis disability. H4500 is a practical instrument that may provide similar results in measuring TEWL as Tewameter and VapoMeter. Finally, battery-free sensory tags appear reliable to measure a trend in TEWL levels.
Conclusion: Tewameter, VapoMeter, Model H4500, and Battery-free sensor tags measure TEWL; each may be better equipped to handle certain skin conditions. Sensory tags are portable compared to the well-used tools like Tewatmere and Vapometer. More detailed comparative instrument efficiency assays in differing conditions should aid comparison of data from one instrument to an other for differing experimental circumstances.
Background: Stratum corneum acts as a protective structure against harmful exogenous agents and transepidermal water loss documents the efficiency of skin water barrier function (Gardien et al., 2016). Tewameter?, Vapometer?, H4500?, and battery free NFC sensors are currently used to measure TEWL. A common technique used to measure TEWL utilizes open chamber diffusion (De Paepe et al., 2005). A limitation to open chamber systems are external confounding variables and vertical probes positioned on skin (Gardien et al., 2016). Other less expensive instruments, are more portable: Tewameter, Vapometer, H4500, battery free NFC sensors, and hollow cone probe are effective in measuring TEWL, but each may be better for different experimental skin conditions. H4500 is the least expensive of the four and sensory tags the most portable. Tewameter and Vapormeter are the most studied and documented for particular skin conditions. A review of recent studies on these devices was conducted to compare them and understand their individuality.
Methods: Research studies were obtained through search engines: Pubmed, Science Direct, and Google Scholar. Strategically, one word or a short phrase was used to search research studies to find more inclusive data. Human studies were chosen over animal studies. The most recent articles were gathered with the oldest study done in 2016 and the latest in 2020. To narrow down search results, key terms were used that decreased the studies identified. Terms included: transepidermal water loss, tewameter, vapometer, sensors, and probes. After obtaining 20 articles that provided a broader understanding of the tools used to record TEWL, seven were reviewed.
Results: Tewameter utilized on burns Gardien investigated the relationship between TEWL and burn scars in 55 adults with healthy, scared, and collateral skin. Tewameter TM300 is an open chamber system and is especially helpful when measuring compromised skin such as burns scars (Gardien et al., 2016). Water loss increases with burn scars severity (Gardien et al., 2016). Mean TEWL in burn scars was significantly higher than healthy skin with a p-value lower than 0.01 (Gardien et al., 2016). The correlation between TEWL and burn scars decreased at the r-value of -0.61 documenting that as scar heals, there is decreased water loss (Gardien et al., 2016). The p-value at the 3-month mark was .021 and at the 12-month mark, 0.002 showing a rapid increased correlation (Gardien et al., 2016). Water loss decreases as skin heals from scars and is accurately depicted with Tewameter measurements.
VapoMeter: Axillary hyperhidrosis takes an emotional, financial, and social toll (Larson, 2011). Larson, used a VapoMeter to measure the course of hyperhidrosis and recovery before and after axillary shaving. Eight (8) patients qualified for study and the patient's age was between 18 and 31 years. Vapometer measured 473 g/m2/h preoperatively and 58 g/m2/h documenting TEWL decrease. Thus Vapometer was an effective tool to measure TEWL, diagnose hyperhidrosis, and confirm surgical success.
H4500: H4500 is a closed chamber system like Tewameter. Fifteen healthy volunteers were enrolled and measurements taken from volar forearms before and after producing artificial barrier damaged skin using stratum corneum tape stripping (Kikuchi et al., 2017). Barrier damage was also produced by 0.5% aqueous sodium lauryl sulfate solution. The results show a confidence interval of 0.835 to 0.978 which means that when utilizing Vapometer, Tewameter, and H4500, all found correlated TEWL measurements on healthy and barrier damaged skin.
Battery-Free NFC sensors: Ali utilized a near field communication (NFC) enabled, battery free, sensor in smartphones like android. These sensors included a skincare sensor tag that measured skin wettedness factor (SWF), and was then plugged into two equations on the smartphone app that computed TEWL levels (Ali et al., 2020). The experiment was collected on eight subjects indoors and six outdoors. Readings were taken multiple times daily and resulted in a trend of increased SWF correlated with increased TEWL. This was an expected result that suggested that the sensors correctly measured TEWL. During the outdoor hours, due to the heat the subjects released more eccrine sweat and therefore had a higher SWF and TEWL levels. This device is portable, battery free, and appears reliable to measure trends in TEWL levels.
Discussion and Conclusion: This manuscript summarized recent experimental data used to measure TEWL and barrier efficacy. The first study focused on testing the Tewameter TM300 and showed that this instrument appeared reliable to use on burn scars. Using Tewameter to measure TEWL multiple times during the healing process assessed healing. Future research can focus on investigating such instruments with a larger sample size, different body sites, and different scar types. VapoMeter was effective in documenting healing; Gardien et al. showed accurate readings taken periodically over months. The readings, if decreasing in number and therefore decreased TEWL, will provide patients reassurance that they are healing. H4500 may provide similar results when compared to Tewameter and Vapometer. Kikuchi et al. found a confidence interval range documenting the correlation between the TEWL measurements between the three tools, but for future studies, it is important to focus on skin conditions that might preferentially be recorded with each instrument. Burn scars and axillary hyperhidrosis are conditions that used Tewameter; Vapometer respectively and it would be beneficial to test H4500 on such skin types to assess if the tool is just as effective in measuring TEWL. It is a practical tool for measuring TEWL on healthy skin and artificially barrier-damaged skin by tape stripping, but it would be relevant to understand if the barrier damage was more extreme would H4500 function efficiently. NFC-enabled battery free sensory tags in a smartphone device that also has an application on the phone to calculate TEWL and SWF is an interesting new and compact device that could have a future in measuring TEWL. Due to its novel nature, it should be compared to devices like Tewameter and Vapometer and compared in a larger population and clinical research situations. In conclusion, Tewameter, VapoMeter, Model H4500, and Battery-free sensor tags measure TEWL effectively. Each maybe better equipped to handle certain skin conditions. Sensory tags are portable compared to the well-used Tewameter and Vapometer. The value of current TEWL measurements suggests not only the need for more informative comparative data, but also methods for comparing data from one instrument to another.
