Skin changes in CVI are clinically observable, but have now been quantified using non-invasive techniques including the The DermaLab Combo® (Cortex Technology ApS), the Skin-pH-Meter® (Courage + Khazaka electronic GmbH) and skin blotting (University of Tokyo). Skin blotting is a non-invasive technique using moistened nitrocellulose membrane strips to quantify specific proteins on intact skin and has been previously used to identify proteins associated with skin tears 1, pressure injuries 2-5 and itch 6.

The aim of the study was to objectively quantify changes in skin morphology and physiology, as well as changes in proteins on the lower legs of individuals with a venous leg ulcer as compared to individuals without chronic venous insufficiency (CVI). A pilot study was conducted on the lower legs of individuals with a venous leg ulcer compared to healthy controls. Sixty participants were recruited, 30 in each arm. Non-invasive measurements of: skin hydration, trans-epidermal water loss (TEWL), melanin, skin thickness, intensity (of ultrasound reflection), temperature and pH, were recorded at three positions: 5 cm above the medial malleolus (LL), laterally half way between the lateral malleolus and the crease of the knee (ML), and the abdomen as a control site. Skin blotting samples were collected from skin above the lateral malleolus to quantify types 1, 3, 4, 7 and 17 collagen, fibronectin, plasminogen activator inhibitor 1 (PAI1), heat shock protein 90 alpha (HSP90α), interleukin 1 alpha (IL1α) and vascular endothelial growth factor C (VEGF-C). Data were analysed using Bayesian ordinal regression due to substantial non-normality across most variables. Age, gender, and body mass index were included as covariates. Site was included as a within-subjects factor where measures were taken at multiple sites. Posterior mean estimates (±0.95 credible interval [CI]) of the difference between CVI and controls from the model are presented.

Melanin, TEWL, skin thickness, and hydration were elevated in the CVI group consistent with lipodermatosclerosis and oedema. Melanin levels followed the gravitational pattern of skin changes in the lower leg in CVI compared to the abdomen. Abdominal temperature was lower in the CVI group, but there were no differences at the leg sites. As expected, skin thickness was increased in the leg in the CVI group. However, 17 of the 60 leg measurements were out of range of the probe sensitivity depth (3.4mm). Collagen 1, 4, IL1α and albumin were higher in CVI compared to controls. Results are presented in Table 1: Skin morphology and Table 2: Skin proteins

Quantification of the skin changes associated with CVI is now possible. This comparative study has demonstrated significant changes in skin morphology in individuals with CVI as compared to healthy controls which was consistent with known pathophysiology and lipodermatosclerosis. Detection of cytokine IL1α probably reflects tissue injury. Further studies are needed to determine whether change is detectable earlier than visible clinical change, enabling timely application of compression and endovenous intervention if relevant, before irreversible damage leads to ulceration, disability, social isolation and cost.

1. Rayner R. Skin Tear Prediction in the Elderly; A Cohort Study Curtin University, 2017. 2. Tamai N, Minematsu T, Maeda T, Yabunaka K and Sanada H. The relationship between skin ultrasound images and muscle damage using skin blotting in wheelchair basketball athletes. Spinal Cord. 2020; 58: 1022-9. 3. Arisandi D, Ogai K, Urai T, et al. Development of recurrent pressure ulcers, risk factors in older patients: a prospective observational study. Journal of wound care. 2020; 29: S14-S24. 4. Kimura N, Nakagami G, Minematsu T, et al. Non-invasive detection of local tissue responses to predict pressure ulcer development in mouse models. Journal of tissue viability. 2020; 29: 51-7. 5. Nakai A, Minematsu T, Tamai N, Sugama J, Urai T and Sanada H. Prediction of healing in Category I pressure ulcers by skin blotting with plasminogen activator inhibitor 1, interleukin-1α, vascular endothelial growth factor C, and heat shock protein 90α: A pilot study. Journal of tissue viability. 2019; 28: 87-93. 6. Sari DW, Minematsu T, Yoshida M, et al. Validity of skin blot examination for albumin and nerve growth factor β to detect itching of the skin in Indonesian older adults. Journal of tissue viability. 2021; 30: 42-50.