PRESSURE SORES

Pressure sores (decubitus ulcers) affect 20% of terminally ill patients. They occur over bony prominences and weight-bearing areas, most commonly sacrum, hips, heels (but also elbows, spine, side of knee, ears and back of head).

There are two types:

  1. Superficial (capillary damage)

  2. Deep (large vessel damage)

Superficial sores begin with capillary damage. They can occur on normal skin if excess pressure is applied (within 30 minutes on a hard surface for an elderly patient or a diabetic). They are painful. They can become deep if neglected.

Deep sores (usually seen only in chronically bedridden patients) start with deep tissue damage. The overlying skin appears intact until it dies and breaks down to reveal a large necrotic cavity. They are full thickness from the beginning and can go down to bone. They are rare in terminally ill patients and will not be discussed further.

Pathophysiology — Pressures on the skin above 30mm Hg (capillary blood pressure) cause tissue damage. After 1 to 2 hours there is irreversible cell damage. Early redness (hyperemia) which still blanches on digital pressure (showing the capillaries are intact) will reverse after 4 hours of pressure relief. Non-blanching hyperemia takes 48 hours of pressure relief to reverse.

«  Pressure damage occurs more rapidly if the skin is also subject to friction (skin damage) or lateral shearing forces (capillary damage) - both of which occur if patients are pulled instead of lifted. All carers should be taught the correct techniques of lifting and turning.

«  Prevention is better than cure (which is often impossible).

Prevention:

The principles of prevention are relief of pressure and friction, which are aided by the following:

  • Whirlpool baths (to relieve pressure)

  • Spenco chair cushions

  • Careful lifting and turning (to avoid friction or shear)

  • Regular turning in bed (at least every 2 hours)

  • Sheepskin mattress and chair covers

  • Spenco (siliconized) mattress covers to reduce friction

  • Ripple or water mattresses

  • Heel and elbow protective siliconized pads

A simple baby sponge taped onto the sacrum (and changed regularly) can bring considerable relief when a bony sacral prominence makes sitting uncomfortable.

Avoid ring cushions which restrict blood flow and increase the risk of tissue damage.

Specialized Dressings:

«  Specialized dressings promote healing only if pressure is relieved.

The concept of moist wound healing was developed in the 1960s. The aim of these newer specialized (and expensive) dressings is to accelerate healing by promoting the ideal micro-environment in terms of temperature, moisture and oxygen supply, and by preventing adherence which damages new granulation tissue.

  Stage of Damage Dressing
1. Blanching erythema Semi-permeable membrane
2. Red ulceration Hydrocolloid dressing
3. Yellow exudate and cavitation Absorbent dressing plus foam covering
4. Black necrotic tissue

Irrigate with streptokinase and treat as in #3

1. Semi-permeable membranes (Opsite, Bioclusive, Tegaderm) are useful for early pressure areas with little exudate, particularly on elbows, hips and insides of the knees. They can reduce pain. The membrane is waterproof and protects the skin if there is incontinence. It can be used successfully on the sacral area but it needs to be skillfully applied.

The area must be carefully cleaned to remove skin grease, avoiding broken skin and the anal margin. Two carers are needed: one to hold the skin tight and the other to apply the membrane. Several overlapping pieces may be needed to cover awkward areas. A piece of stomahesive plaster cut to a triangle can be used to fill the sacral cleft. If the membrane is applied unevenly it can cause friction and more damage.

Small amounts of exudate can be aspirated with a needle (the hole is sealed with another piece of membrane). Larger amounts of exudate prevent the membrane from adhering.

Unfortunately, a significant number of patients develop an allergic reaction to these membranes.

2. Impermeable hydrocolloid dressings (Duoderm, Comfeel) are occlusive, adhesive and waterproof. They have an inner layer that converts to gel when in contact with wound exudate. This provides a good environment for moist wound healing. The lack of oxygen transfer promotes formation of granulation tissue.

The indications for use are:

  • Partial thickness skin loss

  • No infection

  • Little or moderate exudate

The dressing should overlap normal skin by 3cm to 4cm. It can be used alone as it is adhesive. It is changed when the liquid becomes visible as a yellow bubble (when the dressing begins to disintegrate). It can be left in place for 4 to 5 days, but may need changing more frequently. On changing the dressing, yellow gel may be found on the wound surface. This is normal (it is not pus) and should be washed off with normal saline.

The brands of dressings vary in pliability and absorbency.

3. Alginate dressings (FDA approval pending for Kaltostat, Kaltocarb) are particularly useful in promoting healing of deeper pressure sores. The dressings are highly absorbent and convert to a gel which promotes moist wound healing. It is important to pack loosely.

The material conforms to the cavity and is non-adherent and easily washed off with normal saline. It is also hemostatic and controls capillary bleeding. It can be used to hold fluid (such as metronidazole to control smell) in contact with the wound. It needs a secondary covering, preferably a foam dressing.

These dressings need to be changed daily.

Foam dressings (Lyofoam, Synthaderm) absorb excess exudate and maintain a warm, moist environment conducive to healing. Lyofoam-C is impregnated with activated carbon to reduce smell. The foam should overlap the wound by 3cm and is held down by hypoallergenic adhesive tape.

Absorbent powders (Debrisan beads, Duoderm granules) and pastes (Debrisan Wound Cleaning Paste) are occasionally useful if there is a large quantity of exudate. These can cause discomfort. If used excessively they dry out the wound and can be difficult to remove.

4. Black necrotic tissue delays healing and can become infected causing odor. Enzymatic debridement with streptokinase is better than using acidic desloughing agents which can damage granulation tissue. Streptokinase is expensive, but it is superior to chemical debriding agents, and is only occasionally needed. Streptokinase can be applied on an alginate dressing. A dry hard black area (on the heel, for example) can be softened and removed by applying a hydrocolloid dressing.

«  It is important to understand that a pressure area will heal if it is kept clean and relieved of pressure.

Healing can be enhanced by some of the newer dressings which promote moist wound healing — but only if pressure-relieving techniques are adequate.

Routine irrigation of pressure sores with warm saline is recommended to remove exudate. Antiseptics can delay healing. Infected or smelly exudate is best removed with 10% Betadine solution, diluted to 5% with normal saline to avoid damage to new tissue. (Avoid hypochlorites which damage granulation tissue.)

Avoid “remedies” like sugar, honey, oxygen, wine or egg white. There is no evidence that they help, and they distract from the essential treatment, which is pressure relief.

Pressure relieving aids (specialized cushions, mattresses or beds) are useful for both prevention and treatment. A large cell ripple mattress, properly inflated, will reduce interface pressures between skin and surface, as measured by pressure sensors. Sequentially inflated chamber mattresses can reduce pressure enough to heal pressure sores without turning the patient. However, the effect of surface pressure on capillary flow remains poorly understood. More study of preventive techniques is needed to develop optimum methods.

Physical methods of treatment are sometimes used (in addition to pressure relief) to promote granulation tissue and speed healing. They include ice therapy (to reduce the skin edema in early pressure areas with redness only), ultraviolet light, ultra-sound, ionized water vapor and pulsed high-frequency energy. (These methods should not be used to deslough or treat infected wounds.)

Avoid massage which can increase skin damage — any benefit it seems to have is due to associated pressure relief.

Surgical excision of black necrotic tissue may be necessary to reduce infection and smell. Pain in a deep pressure sore is unusual and suggests pus under a necrotic slough, which can be painlessly excised without local anesthetic to release the pus.

Drugs — There is some evidence that oral zinc (such as zinc gluconate tablets) improves skin healing. Zinc is an essential trace element, and it is low in 80% of patients with chronic disease.

In the treatment of pressure sores it is logical to give Vitamin C daily if nutrition has been poor for several months. Vitamin C is essential for the maintenance of healthy collagen and connective tissue in skin. White cell Vitamin C levels are low in 70% of patients with chronic disease.

Broad spectrum antibiotics with anti-staphlococcal action should be given if there is cellulitis.

Comfort care — Even with a short prognosis of a few weeks, wound healing may still be an important aim (to maintain positive attitudes for both patient and carers). During the last few days of life wound healing is secondary to comfort.

Simple and effective management of superficial pressure sores in the last few days of life can be achieved with one of the barrier creams, applied generously and covered with soft gauze. It is cooling and soothing, and reduces friction and lateral shearing forces on the skin. Combined with pressure-relieving techniques it can still produce gradual healing of the skin. Turning routines should be relaxed in the terminal phase if the patient is most comfortable on one side, or if turning causes discomfort.

Patients find washable Spenco (siliconized fiber) mattress covers very comforting, as these reduce pressure and lateral shearing forces.


The author and publisher have taken precautions to ensure that the information in this book is error-free. However, readers must be guided by their own personal and professional standards of good practice in evaluating and applying recommendations made herein. The contents of this book represent the views and experience of the author, and not necessarily those of the publisher.


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