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Introduction To Pressure Injuries

A pressure injury can also be known as a pressure ulcer, pressure sore, decubitus ulcer or bed sore. For ease of reading, this page will refer to the disease state as a pressure injury.

“A pressure injury is defined as localised damage to the skin and/or underlying tissue, as a result of pressure or pressure in combination with shear. Pressure Injuries usually occur over a bony prominence but also may be related to a medical device or other object.”1

Developing damage from pressure injuries and deep tissue injuries is always microscopic, detection in the earliest stages is clinically impossible without technology applications.

Prevention: keeping the skin intact, is therefore not effective under the current standard of care.

Most Common Locations for
Pressure Injuries/Ulcers

Patients may develop pressure injuries in a variety of locations – Vanderwee et al. (2011) identified that the heels and sacrum account for more than 80% of all pressure injuries.2 Occurrence is common over bony prominences but in recent years pressure injury related to medical devices or other object have become more commonly reported.

glassman from the front
glassman from the back

Risk Factors

Patient risk factors should be considered3 when planning patient care.

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Mobility / activity

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Perfusion (including diabetes) and skin/pressure ulcer status

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Skin moisture

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Nutrition and general health status

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Haematological measures

Challenges in pressure injury prevention – keeping the skin intact

Approximately 41% of the admitted adult patient population is at risk of developing a pressure injury4. Figure 1 below (from left to right) shows the transition of patients at risk of developing pressure injuries from being admitted to the hospital towards safe patient discharge, chronic stage pressure injuries requiring enhanced treatment procedures, or death5.

Many patients at risk of developing pressure injuries are missed under the current standard of care. Care pathways are not equipped to detect non-visible tissue damage, meaning those patients with non-visible tissue damage to the left in Figure 1 above remain undetected until damage is manifested on the skin surface. These patients’ anatomies are completely missed under the existing standard of care.

Current risk assessment tools are whole-body rather than anatomy-specific and are subjective to healthcare practitioner experience. Too many patients’ anatomies at risk are misclassified with subjective assessments of risk and, therefore, do not receive appropriate preventive care interventions.

Clinical judgement in detecting a stage 1 pressure injury has a sensitivity of 50.6% and specificity of 60.1 6. Definitive diagnosis of a developing pressure injury, under existing standards of care approach random chance – nearly half of the patient population at risk of developing pressure injuries are either completely missed or do not receive timely, anatomy-specific interventions before damage manifests on the skin surface. In patients with varying skin tones, diagnostic accuracies of detecting stage 1 pressure injuries are even worse, with skin pigmentation obscuring skin and tissue assessments and clinical judgement. In these patient populations, transition probabilities from non-visible tissue damage to stages 2 and above are much higher due to missing diagnosis at stage 1. Reported later-stage pressure injury incidence rates in dark skin tone patients are ~1.8 higher7.

Once a visible stage 1 pressure injury develops, despite enhanced prevention anatomy-specific strategies being provided to patients at this stage, 25.2% progress to a stage 2 pressure injury, 10.5% progress to a stage 3 or 4 pressure injury, and 2.7% require complex treatment procedures including debridement, excision, and surgery8. Transition probabilities from stage 1 pressure injury to more severe broken skin pressure injuries and subsequent pressure injury incidence rates remain unchanged or continue to increase (Figure 2).

Adding new reporting metrics, launching awareness campaigns, Four-eyes Q4, or providing additional training adds burden rather than addressing the root causes of pressure injuries, to detect and treat localized oedema that is known to precede and predict tissue death.

Contemporary Understanding of Pressure Injury Aetiology

Tissue damage in pressure injuries does not appear instantaneously but rather develops from the cell scale, progresses to the tissue level, and finally presents itself on the skin surface and often causes skin and underlying tissue breakdown. Accumulation of interstitial tissue fluid from deformation-induced cell death results in localized oedema that causes further tissue damage.
Sub-epidermal moisture (also known as localized oedema or persistent focal oedema) is the earliest sign of cell death before it manifests on the skin surface.9,10,1

The ICD-10 diagnosis codes in the USA (ICD-10-CM, code L-89) recognize this condition in their definition of a stage I pressure injury as “pre-ulcer skin changes limited to persistent focal oedema.”11 Raised levels of sub-epidermal moisture represent persistent focal oedema, a condition that requires treatment. When left untreated, this localized oedema progresses into visible and palpable stage 1 pressure injuries or deep tissue injuries that rapidly progress into more severe later-stage broken skin pressure injuries that are chronic and debilitating to patients.

Risk Assessment

There are many risk assessment tools available – estimates suggest there could be as many as 90 different versions, however, there is no real consensus as to the optimal risk assessment tools to use.
Risk assessment tools have been reported to be subjective and open to interpretation – additionally results are dependent on the expertise of the assessor.12 In a Cochrane systematic review, Moore et al13 found that neither the Braden nor the Waterlow risk assessment tools made any significant difference to pressure injury incidence rates, when compared to clinical judgement alone.

Skin and Tissue Assessment

The 2019 International Clinical Practice Guidelines1 state that “skin and soft tissue assessment is a key component of pressure injury prevention, classification, diagnosis and treatment”. Routine skin assessment should include for example a visual assessment for erythema, palpation for differences in temperature and tissue consistence1. The same Guidelines note the challenges in assessing darkly pigmented skin where areas of redness may be more difficult to see.

1. EPUAP, NPIAP, PPPIA (2019). Prevention and Treatment of Pressure Ulcers/Injuries: Quick Reference Guide. Emily Hasler (Ed.). EPUAP/NPIAP/PPPIA
2. Vanderwee K, et al. (2011). Assessing the adequacy of pressure ulcer prevention in hospitals: a nationwide prevalence survey. BMJ Qual Saf: 20(3):260-7
3. Guy, H. (2012). Pressure ulcer risk assessment. Nursing Times.
4. Vangilder C., et al. (2008). Results of Nine International Pressure Ulcer Prevalence Surveys: 1989 to 2005. Ostomy Wound Management. Feb;54(2):40-54
5. Padula, W. V., et al. (2020). The cost-effectiveness of sub-epidermal moisture scanning to assess pressure injury risk in U.S. health systems. Journal of Patient Safety and Risk Management, 25, 147-155.
6. Pancorbo-Hidalgo, P. L., et al. (2006). Risk assessment scales for pressure ulcer prevention: a systematic review. J Adv Nurs, 54, 94-110.
7. Oozageer Gunowa, N., et al. (2018). Pressure injuries in people with darker skin tones: A literature review. Journal of Clinical Nursing, 27, 3266-3275.
8. Padula, W. V. et al. (2019). The national cost of hospital-acquired pressure injuries in the United States. Int Wound J, 16, 634-640.
9. Gefen, A. (2018). The Sub-Epidermal Moisture Scanner: the principles of pressure injury prevention using novel early detection technology. Wounds International, Vol 9.
10. Gefen, A. et al. (2018). An Observational, Prospective Cohort Pilot Study to Compare the Use of Subepidermal Moisture Measurements Versus Ultrasound and Visual Skin Assessments for Early Detection of Pressure Injury. Ostomy Wound Manage, 64, 12-27.
11. World Health Organization. (2004). ICD-10-CM United States Clinical Modification: international statistical classification of diseases and related health problems : tenth revision, 2nd ed. World Health Organization.
12. Moore Z., et al. (2019). Risk assessment tools for the prevention of pressure ulcers. Cochrane Database of Systematic Review, Issue 2, Art No: CD006471

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