Provizio^® SEM Scanner FAQ

The device exploits differences between the dielectric constants of materials that make up tissue.

Dry tissue has a low dielectric constant while water has a dielectric constant that is 20x higher.

When the sensor is pressed against an area on the skin, the SEM Scanner measures the electrical capacitance of the sensor, which is affected by the moisture within the underlying skin tissue to a depth of approximately 4 mm.

If inflammatory markers are raised systemically but there is no pressure injury/ulcer (PI/PU), for example as a result of sepsis, the Delta reading at a certain anatomical site susceptible to PI/PU and an adjacent tissue site where there is no injury would be small - because BBI’s data show the systemic conditions will cause rise in SEM readings at both sites, and hence the Delta will be normal. Likewise, in the case of a large-scale oedema that is not localised, such as the legs in lymphedema, if there is no PI/PU the Delta would be small, as readings will be taken at two sites where fluid contents in tissue are similar and therefore baseline moisture levels will be high at the two sites and again, the difference between sites would be small.

Dr Bates-Jensen et al also investigated this aspect– the results of which were published in WRR 2017; May; 25(3); 502-511.

The Provizio SEM Scanner readings are sensitive to changes in local tissue fluid. Moisturisers and other agents which contain water, may affect local SEM readings on a transient basis for up to 20 minutes after application. It is important to apply product according to manufacturer’s instructions and we recommend that the Provizio SEM Scanner is used on clean and dry skin.*

*Evans P., et al. Wounds UK. Vol 16(2); 29-35

Our clinical data suggests that BMI is not a confounder for Provizio SEM Scanner readings. SEM values may vary in reflecting tissue fluid in skin with a higher or lower fat density. However, because body fat is usually proportionally distributed in local scan areas around the bony prominences, the SEM delta reflects the distribution of measurements performed to assess localised tissue health consistently.

1. Scanning should be undertaken with other care procedures such as structured hygiene
2.During which time the skin under the dressing would be assessed as per care Guidelines
3.Therefore there is no additional dressing removal required to facilitate scanning
4. Advanced dressings have specialised adhesives which ensure the vulnerable skin is not damaged on removal
5. As the scanning is undertaken at the same time there is a very limited impact on nurse time and patient disturbance

Please refer to the Bibliography in the Evidence zone

The Provizio SEM Scanner, a wireless handheld device that is indicated for use as an adjunct to the standard of care when assessing patients who are at increased risk for pressure ulcers. The Provizio SEM Scanner is the world’s first device to objectively alert clinicians to specific anatomical areas of a patient’s body at increased risk for developing pressure damage. This data facilitates earlier, and anatomically specific interventions designed to reverse the damaging effects of pressure and shear and prevent PI/PU from breaking through the skin. Patient risk assessments are performed with the Provizio SEM Scanner before visible damage manifests at the skin surface.*

* Okonkwo H., et al (2020). A blinded clinical study using a subepidermal moisture biocapacitance device for early detection of pressure injuries. Wound Repair Regen, (online) 1-11. Available at: https://doi.org/10.1111/wrr.12790 (Accessed: 21 January 2020)

The Provizio SEM Scanner is packaged with the Instructions For Use, and a Charging Hub.

A Provizio SEM Scanner reading is obtained by placing the sensor against the patient’s skin. When the sensor is applied to the skin with sufficient pressure, a SEM reading is displayed on the screen. The sensor must be in complete contact with the skin to acquire a proper reading. The Provizio SEM Scanner displays the most recent SEM Value and, after the third reading, a delta value is displayed, being the difference between the lowest and highest SEM Values from a series of readings performed for an anatomical location (e.g., heels/sacrum). The readings can be taken during routine clinical care such as when visual skin assessments are undertaken or hygiene care procedures.

The Provizio SEM Scanner’s values change in proportion to the dielectric constant of the material in contact with the sensor. Skin and tissue in direct contact with the sensor changes the displayed value according to the level of skin and tissue’s sub-epidermal moisture (SEM). SEM has been studied as an indicator of localised oedema characteristic of pressure tissue damage. The Provizio SEM Scanner’s values are affected by changes in the dermis to approximately 4 mm. Recorded Provizio SEM Scanner values range from 1.0 to 4.5 within the Provizio SEM Scanner’s scale of 0.0-7.0.*

* Gefen A., et al. JWC. 2020

All adult patients who are at risk for developing PI/PUs.

The Provizio SEM Scanner is designed for use by clinical professionals in the clinical setting (by prescription only). The device may be used by clinical professionals such as nurses, nurse practitioners, healthcare assistants and/or clinical professionals specialising in wound care.

Visual skin assessment is frequently reported in published literature to be challenging in dark skin tone patients as identification of skin redness (typical visual diagnosis of category 1 PU) is difficult. In the Prevention and Treatment of Pressure Ulcers/Injuries Clinical Practice Guideline (CPG) ( EPUAP/NPIAP/PPPIA 2019) recommendation 2.7 states “When assessing darkly pigmented skin, consider assessment of skin temperature and sub-epidermal moisture as important adjunct assessment strategies”. The CPG reference B Bates Jenson WOCN 2009; 36(3);277-284 in their strength of evidence. A descriptive cohort study including pooled data from 2 pervious Nursing Home studies, n=66. Goal was to compare SEM values in persons with dark skin tone versus lighter skin tone. The author concluded:
• Higher SEM Values was associated with both concurrent and incident (1 week later) skin damage in persons with dark skin tones
• When more skin damage was observed, SEM values were higher at all anatomic locations.