Introducing the Detection, Treatment and Prevention Effects of Sub-Epidermal Moisture Assessments

Provizio® SEM Scanner detects and measures this localized edema or sub-epidermal moisture. Brunetti et al validated the ability of the device to measure and detect microscopic sub-epidermal moisture changes in a novel ex vivo porcine soft tissue model of localized oedema. When tissue fluid, representative of an oedematous condition in response to early subdermal pressure injury damage, was induced in an ex-vivo porcine skin model, sub-epidermal moisture delta (∆) values correlated with observed healthy tissue and induced localized oedematous tissue in an ex vivo model. Localized fluid volumes above 1 ml result in statistically significant differences in sub-epidermal moisture values between experimental (induced oedema) and control sites (healthy tissue).

These results in addition to bench studies and clinical studies describing the algorithms of sub-epidermal moisture assessment technology, align with the theoretical frameworks laid down in the aetiology chapter of the international clinical practice guidelines for pressure injury prevention in that the device is able to quantify localized edema/persistent focal edema or sub-epidermal moisture, a pathophysiological consequence of pressure-induced damage occurring at the cellular level.

Results from these studies demonstrate the ability of sub-epidermal moisture assessment technology in detecting and measuring localized edema/persistent focal edema or sub-epidermal moisture. These subdermal fluid volumes are not visible until greater fluid volumes are locally present. These data show that skin and tissues absent of visual or tactile symptoms of damage, but which have an SEM delta (Δ) above the clinical threshold (SEM delta (Δ) ≥0.6) are locally oedematous, indicating the development of early pressure-induced tissue damage, which, when left untreated may develop into more severe broken skin pressure injuries or deep tissue injuries.

Outcome: The Provizio® SEM Scanner can be used to detect, monitor, and measure sub-epidermal moisture

This treatment effect is significantly evident in real world settings where the device was deployed alongside existing standards of care. In 69% of patients, nurses reported that the SEM delta (∆) value had changed their clinical decision making (22 sites; 1,591 patients scanned) and 72% of patients received additional interventions based on SEM delta (∆) readings (27 sites; 1,830 patients scanned).¹⁴

This data was further explored by Ousey et al^12,15 in their meta-analyses. Results from this analysis demonstrated that an SEM delta (Δ) prompt was a more decisive call for action than skin reddening: in cases where a high SEM delta (Δ) reading (i.e., ≥0.6) but no skin reddening was recorded, 34.8% (2829/8141) of cases resulted in nurse action, compared with 29.7% of cases (114/384) in which skin reddening was observed but no SEM delta (Δ) prompt was reported.

When a raised SEM delta Δ (≥0.6), is detected by using the device, clinicians should be trained to treat the specific anatomy as if it were a visible stage I pressure injury (skin redness). The Interventions that subsequently follow this clinical action treat the detected increased level of localized edema (persistent focal edema or SEM) condition and subsequently prevent the incidence of broken skin pressure injuries. When the scanner was implemented alongside existing standard pressure injury care pathways a statistically significant 3-fold decrease in risk of pressure injury incidence post-implementation of SEM assessment technology was reported in 28 global facilities (RR=0.38; 95% CI: 0.26 – 0.56; p<0.001).

Outcome 1: Treat raised levels of sub-epidermal moisture as you would treat a stage 1 pressure injury based on your facility protocol.

Outcome 2: Anatomy specific data informs clinicians to treat raised SEM delta (Δ) values with known interventions before visible signs of tissue damage on the skin surface.

1. Raizman et al (2018)¹⁶ conducted a consecutive series study of 284 patients with the objective to evaluate the clinical utility of the SEM assessment technology. The authors concluded that use of the SEM assessment technology to influence clinical interventions resulted in a 93% decrease in HAPI and the Hawthorne effect did not influence the improvements in pressure injury incidence.

2. A real-world case series of 35 patients on a single medical-surgical unit over a two-month period was conducted to evaluate the impact of the SEM assessment technology use for early pressure injury detection on clinical outcomes. When compared to risk assessment tools, several patients were assessed to be “at-risk” by the tools, but their sub-epidermal moisture delta (∆) values indicated no damage was present. The authors concluded that daily scanned proved to be a more effective method of assessing damage objectively as opposed to using visual assessment alone.¹⁷

3. A formal, repeatable, pragmatic framework (a study framework designed to mimic routine clinical care and practices in the real-world care settings) was conducted at Chelsea and Westminster hospitals in the UK¹⁸ to evaluate the impact on reportable pressure injury incidence and the healthcare practitioner experience, changes in decision making and the interventions prompted by SEM results. Six hundred and ninety-seven (697) patients were enrolled during a 6-month period in 4 different wards. Zero pressure injuries were recorded in three wards resulting in an 81% incidence (p=0.011, 95%CI: 0.38-1.77) reduction across all four wards. Improved clinical decisions from clinical judgement based on SEM data were reported in 83% patients (n=578/697).

4. Roper R¹⁹ undertook a 6-week Improvement project comparing the impact on pressure injury incidence and use of Dynamic Therapy Systems. Two pathways were implemented in 7 wards – the first included SEM assessment technology into the standard of care and the second utilized a newly developed equipment pathway. The SEM assessment technology wards (n=2) achieved zero hospital acquired pressure injuries and a 100% reduction in pressure injuries relative to prior year with 75%/79% of patients changed the clinical decision making of the staff introducing additional interventions with 33%/11% reduction in dynamic therapy usage sustained for 6 weeks post project. Whilst the equipment pathway wards (n=5) achieved zero hospital acquired pressure injuries and an 86% reduction in pressure injuries relative to prior year with 64% reduction in dynamic therapy usage for 2 wards, however this was not sustained post project and a 40% increase in 3 wards sustained post project. Roper also estimated potential cost savings of £1,204,708 offset against device purchase related to reduction in spend for dynamic therapy systems, reduction in staff time, cost of dressings, medication, and occupied bed days.

5. Scafide et al²⁰ published a full systematic review of bed side accessible technologies including: ultrasound (n=5), thermography (n=7), Sub-epidermal moisture (n=5), reflectance spectrometry and Laser Doppler (n=1). There is significant detail in the publication with regard to the outcomes of the 5 Sub-epidermal moisture publications included in this evaluation, these publications include 581 patients. The authors state that “evidence from our review supports the use of Sub-epidermal moisture measurement as a potential tool for the early identification of pressure injuries”, they go onto comment that “a body of research regarding SEM measures, which includes multiple, high-quality studies increases the reliability of our findings identified in our review”. They also point out the value in darker skin toned patients.

6. Chaboyer et al²¹ published an independent systematic review to analyze studies that reported the association between oedema measurement and pressure injuries. The rapid systematic review design, quality assessment methodology, GRADE assessment and reporting of meta-analyses uses globally peer reviewed and accepted frameworks. The systematic review showed a strong association between oedema, as a prognostic indicator, and pressure injuries incidence (sacrum and heels) using the SEM assessment technology. Evidence suggested that an abnormal SEM delta (∆) (≥0.6) results in a large increase in the risk of developing pressure injuries and that an abnormal SEM delta (∆) (≥0.6) is a strong indicator of a pressure injury occurring 4 to 5 days later.

7. Mersey Care Foundation Trust, UK²² successfully integrated the technology into every day clinical practice as part of patient’s individual holistic assessment. During their pilot study period, improved clinical decision-making, early implementation of standard of care interventions as a direct result of SEM delta (∆) readings, resulted in a reduction in community acquired pressure injury incidence of 26.7%. The impact of this pilot analysis enabled MCFT to directly correlate implementing SEM assessment technology to their pressure injury incidence reduction objectives.

8. Raine²³ implemented the technology in palliative care (Marie Cure Hospices, UK). The 6-month study period resulted in a 47% reduction incidence rates. Post-study conclusion, patient safety incident reports indicated a consistently decreasing pressure injury incidence rate after fully implementing the device into routine clinical practice. Facility nurses reported a 69% pressure injury incidence reduction in year one of implementing SEM assessments in routine clinical care: 15 months post-study completion. During a period of 6 months in 2020 (year two, pre-COVID-19), a 100% pressure injury incidence reduction was demonstrated for several months.

9. Lustig et al²⁴ developed a novel machine learning algorithm for early detection of heel deep tissue injuries, which was trained using a database comprising six consecutive daily sub-epidermal moisture measurements recorded from 173 patients in acute and post-acute care settings using the SEM assessment technology. On observational analysis of the database the “acceleration effect” was identified – In patients who eventually developed a heel deep tissue injury, SEM delta (∆) values generally increased over time before a deep tissue injury was confirmed through a skin and tissue assessment, the SEM delta (∆) value in the day preceding the discovery of the DTI on the skin surface was typically greater than the average of the SEM delta (∆) readings in the prior measurement days.

10. Oliveira et al²⁵ evaluated the predictive ability of sub-epidermal moisture assessment as a means of detecting early pressure injury damage development among adults undergoing surgery and confirmed early pressure-induced tissue damage in surgical patients in the operating room. Regression analysis of SEM data from 231 patients indicated, a.) the odds of developing an abnormal SEM delta (∆) was likely to increase by 45% with an increase in surgery time (p<0.05), b.) patients undergoing orthopedic surgery were 53% more likely to have an abnormal SEM delta (∆) than non-orthopedic surgery patients (p<0.05), c.) patients having spinal anesthesia were twice as likely to develop abnormal SEM delta (∆) (p<0.05), and, d.) the Braden and Waterlow mobility scores were associated with high sub-epidermal moisture results (p<0.05).

11. Moore et al²⁶ conducted a systematic review to analyze all quantitative animal and human studies that focused on early detection of pressure injuries and studies that reported the association between oedema measurement and pressure injuries. Early detection of pressure injuries using SEM measurement versus VSA was statistically significant; up to 8 days earlier with a median of 4.6 days (95% CI 3.94, 5.28, p<0.05)- this mirrors the results from the earlier study by Okonkwo et al. Sensitivity ranged from 48.3% to 100% while specificity ranged from 32.9% to 83%, the mean sensitivity across four reviewed studies was 72.07%. The mean specificity was 51.96%.

12. Osborne et al²⁷ evaluated 140 adult patients admitted to a critical care unit (CCU) over a 24-week period with a majority of admitted patients being African American with varying skin tones. Pre implementation HAPI incidence was 8.9% (N= 8/90). A 100% reduction in hospital acquired pressure injury incidence was achieved in the implementation period which included 35 African American patients (p<0.05). The relative risk of pressure injury incidence was 1.6 times higher in the pre-implementation group period (95% confidence interval).

Outcome 1: Raised levels of SEM/LO/PFO when left untreated, results in more severe pressure injuries.

Outcome 2: Implementing SEM assessment technology results in up to 100% reduction in hospital acquired pressure injury incidence in multiple care settings.