Monitoring of Venous Ulcers Using a Bioimpedance Measurement Based Method and System (WoundWatch™)

The purpose of this study is to investigate the functionality of a new type of wound monitoring method and measurement system for monitoring healing of venous ulcers. The system is consisted of a wound dressing with electrodes (eDressing), a bioimpedance measurement device and a mobile phone application.

The technical principle of the monitoring method is based on the quasimonopolar bioimpedance measurement. The measurement system consists of a bioimpedance measuring device, a wound dressing with electrodes (eDressing) and a mobile application for use with a mobile phone. The electrode dressing is placed on top of a wound, in contact with the wound tissue. The other necessary dressing layers (such as absorbent dressings and compression bandages) are placed over the electrode dressing. The aim is to keep the electrode bandage on the wound for seven consecutive days. Other dressings can be changed when necessary. However, the electrode dressing can be removed and replaced whenever due to medical necessity. During a study subject visit, the bioimpedance measurement is made, the uppermost dressings are opened carefully and it is ensured that the wound condition is as expected. Upon the replacement of the electrode dressing, the wound is photographed and documented. The wound area is measured, and the findings are recorded. A maximum of 20 subjects (10 to 20 subjects) with venous ulcers will be recruited for the study. Adults with venous ulcer who are applicable for compression therapy treatment and whose wound(s) fit on the area of no larger than 5 x 5 cm and whose wounds are do excrete excessively can be recruited to the study. Previous surgical venous procedure is not an exclusion criteria for enrollment, but surgical procedure can not be performed during the study. A subject shall visit the clinic 2-3 times a week, according to the doctor's or study nurse's assessment. Wound healing is monitored until the wound re-epithelized (>90% of initial wound surface area) or maximum two months. Thus, there will be a maximum of 24 study visits per subject.

The subjects will be monitored using the WoundWatch wound management system two to three study visits per week until the venous ulcer has healed (surface area has decreased at least 90%) or up to two months.

eDressing will be applied along with the compression therapy and the standard absorbing dressings. The subjects will be monitored using the WoundWatch wound management system. The subjects will have two to three study visits per week until the venous ulcer has healed (surface area has decreased at least 90%) or up to two months.

Correlation analysis between the WSI and the wound surface area. The WSI is derived from the bioimpedance measurement results.

Inclusion Criteria: Age at least 18 years The subject has a chronic lower extremity ulcer with a primary etiology of venous insufficiency. The previous venous procedure is not an obstacle to the study Compression therapy can be implemented The wound has a maximum surface area of 5 x 5 cm and can fit in an area of 5 cm x 5 cm. The wound should be located above the ankle, on the skin area where the electrode dressing can be placed properly. The wound is not deep with steep edges or cavity-like The wound is not highly excreting The wound can be expected to heal within two months (area reduced ≥ 90% from baseline) The subject gives consent to the study and commits to following the instructions of the medical staff Exclusion Criteria: Clinical wound infection at the time of the study The subject has an intravenous procedure within 2 months Significant arterial circulatory disorder or adherence problem that prevents compression therapy Subject movement 2-3 times a week during the study to the study site is difficult to arrange Diagnosed epoxy resin allergy Any other reasons of potential study subject non-compliance by the opinion of the investigator

Kekonen A, Bergelin M, Eriksson JE, Vaalasti A, Ylanen H, Kielosto S, Viik J. Bioimpedance method for monitoring venous ulcers: Clinical proof-of-concept study. Biosens Bioelectron. 2021 Apr 15;178:112974. doi: 10.1016/j.bios.2021.112974. Epub 2021 Jan 7.

Kekonen A, Bergelin M, Johansson M, Kumar Joon N, Bobacka J, Viik J. Bioimpedance Sensor Array for Long-Term Monitoring of Wound Healing from Beneath the Primary Dressings and Controlled Formation of H2O2 Using Low-Intensity Direct Current. Sensors (Basel). 2019 May 31;19(11):2505. doi: 10.3390/s19112505.

Kekonen A, Bergelin M, Eriksson JE, Vaalasti A, Ylanen H, Viik J. Bioimpedance measurement based evaluation of wound healing. Physiol Meas. 2017 Jun 22;38(7):1373-1383. doi: 10.1088/1361-6579/aa63d6.