Pressure ulcers: assessment and prevention (Part 1)

Dr. Almoutaz Alkhier Ahmed
Saudi Arabia / Gurayat north
Diabetic Center
e.mail:khier2@yahoo.com

Epidemiology:
Pressure ulcers are considered among the main problems in healthcare settings in the United States. Estimates of the prevalence and incidence across all care settings continue to vary, ranging from 0.4 - 38% in general acute care, 2.2 - 23% in long term care and 0.0 - 17% in home care⁽¹⁾.

Pressure ulcer has been defined as any lesion caused by unrelieved pressure resulting in damage to underlying tissue. Although pressure as an external force is a key causative factor, other contributing factors that add insult to skin or tissue integrity cannot be diminished or overlooked.

Kroger at al worked to find the prevalence of pressure ulcers in hospitalized patients in Germany during the year 2005 using the National Statistics published by the Federal Statistical Office. They found that 0.6% were referred with pressure ulcer as principal diagnosis and 1.19% had at least one additional diagnosis pressure ulcer. Also they noticed that pressure ulcers occasionally occurred in elderly people and the most common site for their occurrence was the ischium, the sacrum and the heel respectively⁽²⁾.

Since 1989, results from the International Pressure Ulcer Prevalence Surveys conducted by Hill - Rom, have been used to document aggregate prevalence rates of pressure ulcer⁽³⁾.

During each of the nine surveys conducted between 1989 and 2005, clinical teams, mostly from USA (teams from Canada and Saudi Arabia participated after 2003) assessed admitted patients on assigned dates. The results of these surveys showed that nosocomial pressure ulcer prevalence ranged from 5.6 - 9.2% in the year 1989 and became 15.5% in the year 2003 and dropped to 10% in the year 2004.

Also they noticed in these surveys that the most common sites for pressure ulcer to occurr were the sacrum, heels and buttocks respectively⁽³⁾. Unfortunately no data was available from the Middle East countries on the current situation of pressure ulcers among hospitalized patients. Most of the small data are personal observations or small cross-sectional hospital based studies.

Etiology:
The pathophysiology of pressure ulcers is a complex one. A lot of factors participate in its occurence. Some of them are external and not related to the patient and others are internal factors related to the patient (Table 1).
Good understanding of these factors helps in understanding the pathophysiology of pressure ulcers⁽⁴⁾.

Table 1: factors increase the risk for pressure ulcers:
- Being bedridden or in wheelchair
- Fragile skin
- Having a chronic condition such as diabetes
- Inability to move certain parts such as after spinal injury
- Malnutrition
- Mental disability from certain conditions
- Older age
- Urinary incontinence or bowel incontinence

Due to the importance of the external factors, I will discuss them in some details.
External factors or forces contributing to pressure ulcer formation:
Pressure:
Definition:
It is the perpendicular force that results in compressing the soft tissue over bony prominences against outside surfaces (Figure 1).

Figure 1:

"Reproduction of the National Pressure Ulcer Advisory Panel (NPUAP) materials in this document does not imply endorsement by the NPUAP of any products, organizations, companies, or any statements made by any organization or company."

Pathophysiology:
Usually there is equilibrium between capillary beds and outside pressures. When the external pressure exceeds that of the pressure within the capillary beds, this causes disruption in the flow of blood and nutrients to the body tissues.

Continuation of the pressure and sustained disruption in the flow result in localized ischemia, hypoxia, tissue acidosis, edema and eventually cellular necrosis.

High risk areas:
- Areas over bony prominence such as occipit, shoulders, scapulae and escheat tuberosities.
- Areas in contact with foreign bodies such as catheters or malpositioned extremities.

Shear:
Definition:
This is the force produced when adjacent surfaces slide across one another (Figure 2).

Figure 2:

Pathophysiology:
Skin and superficial fascia remains fixed against the external surface while the deep fascia and skeleton slide down. This situation can cause stretching, pulling and change to the angle of the vessels, resulting in tissue ischemia.

High risk:
- Bed bound individual, particularly when bed heads are elevated more than 30 degrees.
- Chair bound individual.

Friction:
Definition:
This is the force resulting from repeated movement of the skin over surfaces (Figure3).

Figure 3:

Pathophysiology:
This force alone does not account for deeper pressure ulcers, but contributes to the onset of ulceration. Frequent friction could lead to frequent skin breaks resulting in increase potential of bacterial invasion and damage from moisture

High risk:
- Bed bound individuals
- Chair bound individuals

Moisture:
Pathophysiology:
Prolonged exposure to moisture may lead to maceration of skin layers or at worst, denuded or broken skin through prolonged exposure to moisture, particularly moisture from a caustic origin.

High risk:
- Patients with urine and / or fecal incontinence
- Patients with wound drainage

Assessment tools:
Assessment is an essential procedure that helps clinicians to make correct decisions. Ongoing assessment of the patient risk status coupled with the progress in healing may change the needs related to dressing, support surfaces and other interventions. Also assessment of wound healing coupled with assessment of the specific wound parameters will change the choice of topical treatment or adjunctive therapies.

Assessment of pressure ulcer status falls into 3 main categories:

1) Assessment of the degree of tissue destruction or wounding
There are numbers of classification systems which have been developed to assess wounds; some use stages, some use grades and some use wound characteristics and color to determine treatment.

The 4 stage system:
This system has become widely accepted and used. It originated with Shea in 1975⁽⁵⁾ and was updated in 1987 by the International Association of Enterostomal Therapy (now Wound, Ostomy and Continence Nurses Society)⁽⁶⁾. In 1989, the National Pressure Ulcer Advisory Panel (NPUAP) further updated the system⁽⁷⁾. The NPUAP further revised the system in 1998 by adapting a change in the language related to Stage 1 pressure ulcers⁽⁸⁾.

The stages are defined below (Figure 4):
Stage 1: Skin intact but reddened for greater than 1 hour after relief of pressure.
Stage 2: Blister or other break in dermis with or without infection (partial thickness skin loss).
Stage 3: Subcutaneous destruction into muscle with or without infection (full thickness skin loss).
Stage 4: full thickness skin loss with involvement of bone or joint with or without infection.
Stage 5: Unstagable where there is a shear or complete tissues necrosis.

Figure 4: Stages of pressure ulcer

2) Assessment of healing
Through the years, several tools have been developed for assessing the healing wound.
Among them, two tools have been validated.
These tools are:

a) Pressure Sore Status Tool (PSST):
This is a research-based instrument for assessing and documenting pressure ulcers that incorporates multiple indices for pressure ulcer assessment, provides for quantification of observations and allows for tracking the condition of pressure ulcer over time⁽⁹⁾.
The PSST contains 15 wound-assessment indices, with location and shape indicated at the top of the form, then 13 other indices with possible scores of 1-5 for each wound characteristic, with1 being the more positive characteristic and 5 being the least. Upon completion is a total score between 1- 65, with 1 indicating tissue health and 65 indicating wound degeneration.

b) Pressure ulcer scale for healing (PUSH Tool 3.0):
It is validated for use in ulcer healing assessment⁽¹⁰⁾.
The PUSH tool is designed as a quick, reliable tool to monitor changes in pressure ulcer status over time.

The tool comprises 3 different records and directions.
The first record is for assigning sub-scores to 4 different wound characteristics:
i) Length and width of the ulcer
ii) Exudates amount (none, light, moderate and heavy).
iii) Tissue type (closed, epithelial, granulation, slough, necrotic tissue)

Once sub-scores are added, the scores are plotted on pressure ulcer healing records and graph to demonstrate healing status. If the score goes up, the wound is deteriorating, if the scores go down the wound is healing.

c) Pressure ulcer assessment documentation forms:
It is a form that provides an orderly and logical review of important parameters and characteristics of the pressure ulcer. This is the most frequently used method of documentation of a pressure ulcer assessment.

It helps to collect complete, comprehensive information which enables the practitioner to compare subsequent evaluations to confirm improvement in the pressure ulcer or to alert the practitioner to deterioration.

Recommended parameters / characteristics to be included in pressure ulcer assessment in almost all health care settings are:
- Location
- Size
- Peri-wound appearance
- Ulcer edge
- Tissue type
- Exudates description
- Exudates amount
- Odor
- Structure
- Pain

3) Assessment of the wound itself
Reliable wound assessment remains a clinical challenge for wound care clinicians. The MEASURE mnemonic (Table 2) presented a simple conceptual framework that may act as a basis for a consistent approach to local wound assessment⁽¹¹⁾.

Table 2: MEASURE mnemonic

CONCLUSION

Prevention of pressure ulcers is the ultimate goal in all patients who are at risk. Recognition of patients at risk is an important issue. Health care providers work with patients at risk of developing pressure ulcers should be taught how to recognize the risk factors and how to neutralize these factors.

Systematic approach in the assessment of pressure ulcers and documentation of the assessment is an important helper to right decision making. Using tools that assess healing is a good practice that enables health providers to evaluate their plan of management.
Realistic goals must be well thought out and appropriate to the specific patient.

1. Cuddigan J, Ayello EA, Sussman C, eds. Pressure ulcers in America: Prevalence, /incidence and Implication for the Future. Reston, Va: NPUAP; 2001:184
   
2. Bergstrom N, Bennett MA, Carlson CE, et al. Clinical Practice Guideline Number 15: Treatment of Pressure Ulcers. Rockville, Md: Agency for Health Care Policy and Research, US Department of Health and Human Services; 1994. AHCPR publication 95- 0653.
   
3. Kroger K , Niebed W, Maier I, Stausberg J, Gerber V, Schwarzkopf A. Prevalence of pressure ulcers in hospitalized patients in Germany in 2005: Data from the federal statistical office.Gerontology.2008
   
4. Vangilder C, Macfarlane GD, Meyer S. Results of nine international pressure ulcer prevalence surveys: 1989 to 2005.Ostomy Wound Manage.2008;54 (2) : 40- 54.
   
5. Shea, J.D. (1975). Pressure sores classification and management. Clinical Orthopaedics, 112, 89-100.
   
6. International Association of Enterostomal Therapists. (1988). Dermal wounds: Pressure sores: Philosophy of the IAET. Journal of Enterostomal Therapy, 15, 4-17.
   
7. National Pressure Ulcer Advisory Panel (NPUAP). (1989). Pressure ulcer prevalence, cost, and risk assessment. Consensus Development Conference Statement. Decubitus, 2, 24-28.
   
8. National Pressure Ulcer Advisory Panel (NPUAP). (1997). 1997 NPUAP Consensus Development Conference Definition. Washington DC: Author.
   
9. Bates - Jensen BM. Pressure ulcer assessment and documentation: the pressure sore status tool. In: Krasner D, Kane D, eds. Chronic wound care: A clinical source Book for healthcare professionals.2nd Ed. Wayne, Pa: Health Management Publications, Inc: 1997:38.
   
10. The National Pressure Ulcer Advisory Panel > PUSH tool. Available at http://www.npuap.org/pushins.html. Accessed March 6, 2007.
    
11. Keast DH, Bowering K, Evans W and et al. Measure: A Proposed assessment framework for developing best recommendations for wound assessment. Wound Repair Regen. 2004; 12: S1 - S17.