Eamonn Brady, MPSI, provides a clinical overview of wound care
Pressure ulcers are lesions caused by unrelieved pressure that results in damage to the underlying tissue. Generally, these are the result of soft tissue compression between a bony prominence and an external surface for a prolonged period of time. Pressure ulcers are among the most common conditions encountered in patients in hospital or requiring long-term institutional care.
American studies have shown that pressure ulcers are also common among patients admitted to nursing homes, with reported rates ranging from 10-to-35 per cent.
Manifestations and diagnosis
Pressure ulcers are usually easy to identify by their appearance and location overlying a bony prominence. It is important to distinguish pressure ulcers from ulcers that result from diabetic neuropathy or arterial or venous insufficiency. They may also be confused with other conditions that cause redness of skin, such as cellulitis. Superficial moisture-induced lesions, such as maceration (softening and whitening of skin) over a bony prominence, should not be labelled as pressure ulcers. Characteristics of lesions that need to be distinguished from pressure ulcers are:
European Pressure Ulcer Advisory Panel grading system:
Unstageable – Full thickness tissue loss in which the base of the ulcer is covered by slough (yellow, tan, gray, green or brown) and/or eschar (tan, brown or black) in the wound bed.
Eschar often covers deep ulcers, making it difficult to determine whether lesions are stage 3 or 4. Until enough slough and/or eschar is removed to expose the base of the wound, the true depth, and therefore stage, cannot be determined.
There are external factors that contribute to pressure ulcers. The four main external factors that lead to the development of pressure ulcers are pressure, shearing forces, friction, and moisture.
Pressure: Pressure applied to the skin in excess of the arteriolar pressure (32mmHg) prevents the delivery of oxygen and nutrients to tissues, resulting in tissue hypoxia, the accumulation of metabolic waste products, and free radical generation. Pressures are greatest over bony prominences where weight-bearing points come into contact with external surfaces. Extensive deep tissue damage may occur with little or no evidence of superficial tissue injury. A deep necrotic wound may be the first evidence of pressure-induced injury, rather than a gradual progression of an ulcer from stages 1 through 4.
Patient factors that may contribute to pressure ulcer development include immobility, incontinence, nutritional status, circulatory factors, and neurological disease.
The European Pressure Ulcer Advisory Panel made the following four points in relation to prevention of ulcers:
Proper positioning of bed-bound individuals is recommended, including a regular turning and repositioning schedule, with particular attention to vulnerable tissue covering bony prominences such as the sacrum. Typically, a two-hour interval is recommended.
In addition to regular turning, the position of bed-bound patients is likely to be important. It is recommended that:
Chair-bound patients may generate considerable pressures over the hip joints; they should be repositioned at least every hour with wheelchair push-ups or with tilting of the seat to reduce contact between the patient’s buttocks and the seat. Patients who are cognitively intact and are able to use their upper extremities can be trained to shift weight even more frequently, using monitoring devices as a reminder.
Support surfaces (mattresses) – these products can be classified as either non-powered, overlays, or powered. Non-powered support surfaces (previously known as static) do not require electricity and consist of mattresses that are made of gel, foam, air, or water, or a combination of these. They work by distributing pressure over a wider body surface area.
Overlays are support surfaces designed to be placed on top of another support surface.
Foam, air, or water overlays may be used for patients who can assume a variety of positions without bearing weight on the ulcer. Powered or dynamic support surfaces require electricity to alternate air currents in order to regulate or redistribute pressure against the body. Examples include alternating pressure mattresses, low air loss beds, and air fluidised mattresses.
For chair-bound patients, appropriate wheelchair cushions are recommended. Donut cushions should not be used, as they increase oedema and venous congestion and concentrate the pressure to surrounding tissue. The three main types of seat cushions include gel and foam seat cushions, non-powered adjustable cushions and powered adjustable seat cushions.
Encouraging patient mobility is key to the prevention of pressure ulcers. Several approaches may be helpful to minimise immobility, including:
If oral intake is not adequate to ensure sufficient calories, protein, vitamins, and minerals, nutritional supplementation with enteral and parenteral nutrition (PEG feed) is recommended to correct deficiencies. Increased dietary protein intake promotes the healing of pressure ulcers. The protein target is usually 1.5g/kg/day. Cubitan is an example of a high-energy, high-protein oral nutritional supplement (ONS) with wound-specific nutrients (arginine, vitamin C, zinc, vitamin E).
It increases healing times of pressure sores in undernourished patients. However, it is important that oral nutritional supplements are reviewed regularly by a dietitian. While high-protein ONS such as Cubitan have an important role in helping heal ulcers and other wounds, they should be discontinued promptly once the wound has healed. Food is the best vehicle for appropriate nutrient consumption.
According to the National Medicines Information Centre in St James’s Hospital, Dublin, no studies have yet determined the optimum usage of ONS in terms of the most appropriate patients, the optimum dose and duration of use. Despite lack of evidence, ONS has a role in many circumstances; therefore, it is important to liaise with nutrition specialists such as dietitians before ONS can be recommended.
For the added reason of the high cost of ONS to the State, the HSE also recommends that ONS is only commenced after the patient is assessed by a dietitian.
There is no conclusive research evidence to guide healthcare professionals’ decision-making about which dressings are most effective in pressure ulcer management. However, professional consensus recommends that modern dressings (ie, hydrocolloids, hydrogels, foams, films, alginates, soft silicones) should be used in preference to basic dressing types, ie, gauze, paraffin gauze and simple dressing pads. Examples of effective silicone dressings include the Mediflex, Mepilex, and Mepitel ranges.
Grade 1 ulcers may be dressed with transparent films for protection, ie, Medisite, Tegaderm, Opsite. Grade 2 pressure ulcers usually require an occlusive or semi-permeable dressing that will maintain a moist wound environment, ie, Comfeel Plus, Granuflex.
Ulcers with heavy exudate require an absorptive dressing to avoid build-up of chronic wound fluid that can lead to wound maceration and inhibit healing. An appropriate wound dressing can remove excess wound exudate while maintaining a moist environment to accelerate wound healing.
Dressings with absorptive qualities include alginates, ie, Kaltostat, foams, ie, Allevyn, Biatain, and hydrocolloids, ie, Aquacel, Comfeel, Granuflex, and the Medipad range of wound pads.
Desiccated ulcers are dry ulcers that lack wound fluids, which help promote healing. Thus, pressure ulcer healing is promoted by dressings that maintain a moist wound environment while keeping the surrounding intact skin dry. Choices for a dry wound include hydrogels, ie, Granugel, Intrasite Gel and hydrocolloids, ie, Aquacel, Comfeel, Granuflex.
Necrotic tissue promotes bacterial growth and impairs wound healing. Wound debridement may involve any of five approaches: Use of sharp dissection (take care when doing this on heels), mechanical debridement (wet-to-dry dressings), application of proteolytic enzymes, autolytic debridement under occlusive dressings (hydrocolloids or hydrogels), or biosurgery with sterilised maggots.
References on request
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