A pressure ulcer is an ischaemic necrosis of the skin and subcutaneous tissue caused by unrelieved and prolonged vascular compression on a specific area of the body, usually between a bony prominence and a supporting item such as a bed or chair.
This external pressure is transmitted through the support (bed, armchair) and affects the part of the body bearing the support. The extent of the pressure ulcer depends on several factors, particularly the intensity of the pressure, the duration, the resistance of the tissue to pressure and the general condition of the patient.
Locally, tissue damage is the result of three forces:
AETIOLOGY (read more...)
Several factors contribute to the development of pressure ulcers. A distinction is made between:
- factors independent of the patient (extrinsic risk factors)
- factors related to the patient's condition (intrinsic risk factors).
EXTRINSIC RISK FACTORS (INDEPENDENT OF THE PATIENT)
Pressure is a perpendicular force applied to a specific area of living tissue. This pressure is applied particularly on bony prominences. Where soft tissues between the bone relief and the underlying support are compressed. These forces correspond to the distribution of the body weight over the contact surface area.
These are forces applied between two surfaces in contact with each other and moving relative to each other. These forces are often responsible for the initial skin abrasion.
These are forces that cause slip and torsion of the subcutaneous layers. They exist especially in an unstable semi-seated position in which subcutaneous layers are subject to a kneading type force.
INTRINSIC RISK FACTORS (RELATED TO THE PATIENT'S CONDITION)
- Elderly patients have a greater risk of developing a pressure ulcer.
Poor skin condition
- Skin resistance is reduced with age, long term corticosteroid treatment and deficiency conditions.
Conditions that reduce sensitivity
- Impaired sensitivity and motor control
- Anaesthesia, hypoesthesia
- Spinal and neurological conditions
- Neurological disorders which prevent pain signals associated with excessive weight-bearing and reflex actions leading to a position change.
- Hypoxia due to arterial disease and/or venous return anomalies, diabetes
- Cancer, infection, anaemia and hyperthermia are all risk factors.
- Maceration due to both urinary and faecal incontinence may cause skin abrasions.
- Malnutrition appears to be a major risk factor in the development of pressure ulcers. All pressure ulcer treatment must be accompanied by appropriate dietary management.
LOCATION (read more...)
80% of pressure ulcers are on the sacrum or heels. Another possible location is the trochanter (hip bone).
PATIENT AT RISK IN A SITUATION CONDUCIVE TO THE DEVELOPMENT OF PRESSURE ULCERS
An orthopaedic or neurological disorder combined with a deterioration in the general condition of the patient causes immobility which will increase bearing pressures (ie: a surgical operation, prolonged immobilisation, age, etc.).
This risk is demonstrated by a local red area that might be reversible and which disappears under pressure. This stage in the formation of pressure ulcers can be avoided by the application of appropriate treatment and preventive measures.
STAGES (read more...)
Pressure ulcers can be broken down into four stages. It is important to consider the four stages as being four manifestations of the pressure ulcer, and not four phases that necessarily follow each other. In some patients, a pressure ulcer can begin with a phlyctena (blister) or a superficial wound, or even a deep lesion (ie: a black necrotic patch on the heel). A pressure ulcer can sometimes develop into a black necrosed spot (deep pressure ulcer).
GRADE 0: BLANCHABLE ERYTHEMA
Patient at risk with no formed lesion may have a stage 0 pressure ulcer.
The sub-clinical stage (no lesion, skin intact) can also be manifested by a red area but a red area that is reversible, in other words this red area will turn white under pressure (see picture).
This stage 0 is a warning stage.
GRADE 1: NON-BLANCHABLE ERYTHEMA
This is a red patch, an oedema, an induration that is sometimes hot and often painful.
This red area (hyperthermia) does not turn white under pressure.
This persistent erythema is a manifestation that the epidermis or even the dermis is affected.
Special care is necessary at this stage. Massaging the area is not recommended as it could exacerbate the situation.
The skin is not broken at this point.
GRADE 2: BLISTER
This stage results in:
- either a phlyctena leading to separation of the epidermis
- or epidermal and then dermal-epidermal erosion
GRADE 3: SUPERFICIAL ULCER
The epidermis, dermis and hypodermis are affected, without the muscle fascia being damaged. The picture shows a pressure ulcer covered with a dry blackish necrotic plaque adjacent to healthy tissue. This is a definitive sign of devitalisation of the underlying tissues.
The external appearance is deceptive and does not provide any indication of the extent or depth of the lesions.
It is delimited by a groove which, as it progresses, will cause separation of the entire plaque. This dry necrosis tends to become wet and subsequently fibrinonecrotic.
GRADE 4: DEEP ULCER
Tissue damage goes beyond subcutaneous tissues and affects underlying structures (muscle fascia, tendons and/or joints).