EUROPEAN PRESSURE ULCER ADVISORY PANEL

MEDICAL MANAGEMENT OF PRESSURE ULCERS. Part 2

Dr Mary Bliss, London, adapted from a talk given at the Fifth Oxford European
Wound Healing Summer School held at St Anne's College, Oxford, 28 June - 1 July 2000

PRESSURE RELIEF

Grab bars and bed cradles
Two simple measures which help pressure relief and make patients more comfortable which have largely been forgotten are the grab bar (or monkey pole) and the bed cradle.

Providing it is carefully positioned above the patient with the arms at full stretch, the grab bar [Figure 5] is an invaluable aid to assisting a weak patient to lift himself and relieve his own pressure areas. Posture in bed, particularly assisting patients to sit upright when they experience discomfort, is vitally important. A bed cradle over the legs and feet removes the weight of the covers from these vulnerable areas and makes it easier for the patient to move to relieve pressure pain in the heels.

Repositioning
If no part of the body remains in contact with a resistant surface for long enough, pressure necrosis will not occur. But it is important to realise that the length of time which the tissues can withstand ischaemia and recover may be much less in an acutely ill patient than in a healthy person. In a patient with a new spinal cord injury, less than half an hour of unrelieved pressure may be sufficient to cause a sore.²⁴ Thus, if a patient is found to have a red heel (a Grade 1 pressure sore), it should immediately be propped off the bed surface, e.g., by means of a pillow under the calf.

However, except in intensive care wards or private nursing homes with 1:1 nurse patient ratios, reliance on regular repositioning alone as a method of pressure relief is unlikely to be successful. Individual care should be the aim of every nurse, but it is impracticable for preventing sores in the very large number of patients at risk in geriatric and orthopaedic wards and in the long stay units and nursing homes. It is labour intensive and is often difficult or impossible for patients who have to sit up, or who have numerous catheters or monitoring lines, or unstable fractures. Elderly patients dislike being turned (or tilted) and usually beg to be returned to lie on their backs, or move out of position. The lateral position also causes high pressures over the greater trochanter. This can cause severe pressure injuries in sick patients if maintained for an hour or more. Longer periods may be safe if the patient is also nursed on an effective pressure relieving mattress.²⁵

If it is practicable and the patient can tolerate it, repositioning should be carried out as often as possible whether he has a pressure relieving support or not. Changes of posture have many benefits besides relieving pressure, e.g., improving lymph flow,²⁶ helping to prevent joint pain and contractures, and reducing stasis in the lungs²⁷ and bladder²⁸ as well as providing an opportunity for personal care.

Pressure relieving supports
An effective support which prevents prolonged pressure on the body is an invaluable aid for nursing a sick patient but it must be able to prevent tissue breakdown very ill as well as less ill patients. As we have seen, a patient's condition can deteriorate rapidly so that there is no place for partially effective or 'first line' supports on which he is at risk of developing a tissue injury before he can be transferred to a more effective machine. This approach is like treating a patient with pneumonia with a cough linctus until he becomes sufficiently ill to be given an antibiotic.
Although the idea of giving a powerful support to all vulnerable patients in the first instance may seem expensive, the money saved by their more rapid recovery if they do not develop sores, and the reduced nurse time and cost of expensive dressings, to say nothing of the patient's comfort and the risk of litigation, is likely to outweigh the initial cost. (The Touch Ross Report in 1993²⁹ which concluded that it was cheaper to treat than to prevent sores was based on calculation of the nurse time required for regular repositioning of at-risk patients assuming that there were no effective pressure relieving supports, which was and is untrue.^25,30 Furthermore, pressure relieving machines do not need to be particularly costly or sophisticated to be effective. Simple alternating pressure overlays are not much more expensive than less efficient soft static supports if the latter are cared for and replaced in accordance with manufactures' instructions.³⁰ Finally, a pressure relieving support is usually only necessary for the first week of a patient's illness whist he is most at risk. It can safely be removed once he has regained his normal level of mobility. Of course, if he has been allowed to develop a sore during this time, pressure relief and continued bed rest may be needed for much longer. Some chronically ill or dying patients may need supports indefinitely.

If we exclude turning bed which are mainly only useful for spinal injury patients, pressure relieving supports fall into two categories: low pressure (soft) supports and alternating pressure supports. It is important to understand the distinction because they work on entirely different principles.

Low pressure supports
Figure 6 shows a diagram of a low pressure support. These aim to adapt to the body contours so as to distribute the weight as widely as possible thus preventing high pressures over bony prominences. The oldest, and one of the most effective, was the waterbed.³¹ Providing the bath was sufficiently deep and the cover protecting the patient from the water was sufficiently loose, so that patients were able to sink into it as if they were floating, pressures were equalised over the whole of the under surface of the body and they did not get sores. However, the water bed's instability made it very difficult for nursing patients and it has since be superseded by the low air loss and air fluidised bead bed.³²

These achieve a similar floating action by means of automatically inflated air sacs of air fluidised beads respectively. Their advantage over the waterbed is that their floating action can be controlled or stopped when necessary to permit nursing procedures. Their main disadvantages are: the enforced immobility of the patient which reduces reactive hyperaemia and lymph flow and their size and cost which prohibit their use for preventing sores in the very large number of patients at risk in hospitals and the community. They are mainly used for healing. Low air loss mattress replacements and overlays which are easier to manage than flotation beds are available but their effectiveness has not yet been tested in a clinical trial.

Efforts have been made to find cheaper, more portable low pressure alternatives to flotation beds, e.g., slit foam, static air, fibre, gel, but none have shown to be able to prevent sores in very ill patients.^25,30,34 Although many appear to provide low interface pressure profiles in healthy volunteers,³⁵ they are apparently unable to modify pressure over internal bony prominences sufficiently to prevent deep tissue distortion and ischaemia in illness. They should therefore be avoided unless they can be used in conjunction with regular repositioning.

Alternating pressure mattresses
Alternating pressure mattresses [Figure 7] work on a different principle to soft supports. They have more in common with the method of repositioning than that of reducing of pressure over bony prominences. Instead of preventing pressure, they aim to continually change the supporting areas of high pressure on the body so that no part remains ischaemic long enough to cause cell death. Alternate air cells inflate and deflate about every 5-10 minutes, thus constantly changing the points of support, and therefore pressure [Figure 8] on the body. The mattresses are not designed to be particularly soft: indeed they must have sufficient air pressure to lift the patient off the surface of the underlying bed or mattress so that areas overlying deflated cells are effectively relieved of pressure. The continual movement on the body also helps to stimulate reactive hyperaemia and lymph flow.⁵ Simple large celled alternating pressure overlays (cells 10 cm or more in diameter) have been shown in randomised controlled trials to prevent pressure injuries in intensive care patients³ and in deteriorating long term elderly patients.²⁵

Alternating pressure overlays are light and portable and easy to install for patients at risk in hospital or in the community. They have a reputation for being uncomfortable, but this is largely because they are often used inappropriately. Most patients who are sufficiently alert to complain about the discomfort of alternating pressure are well enough not to be at risk of developing a pressure injury. Comfort is not important in an unconscious patient, and most geriatric patients, the largest group at risk, have so much sensory inattention that they are unaware that they are lying on special supports.

However, some patients with non neurological diseases, such as cancer or rheumatoid arthritis cannot tolerate the continual movement of an alternating pressure mattress and for these a low pressure support such as a low air loss overlay may be more appropriate. As with other life support equipment, pressure relieving mattresses can safely be removed in the majority of patients when they have recovered from their acute illness. This prevents unnecessary discomfort and facilitates rehabilitation as well as freeing the supports for use for other patients.

Deep and double layered alternating pressure mattress replacements are available and are widely used for intensive care patients and for healing sores. However, they are less portable, and except for heavy or bony patients who are liable to 'bottom through' single layer supports, there is no evidence that they are move effective than good quality overlays to justify their considerable extra cost.

Policy and education
It is not sufficient simply to have pressure relieving supports which work. They must be immediately available, in hospital or in the community, whenever a patient is found to be at risk, and removed when they are no longer needed. Like all medical equipment, they must be correctly installed and continually checked to ensure that they are working properly. They must be robust enough to withstand constant use, have warning indicators in the event of failure and be regularly serviced.

The National Health Service continues to fail on nearly all of these counts. Training in pressure care is still almost non existent for doctors and is deteriorating generally for nurses. In 1989, a British Standard for Alternating Pressure Air Mattresses was published which resulted in stronger machines than had been previously available, but at the same time servicing was mainly relegated to manufactures. This has not only put up costs but has had the effect of putting pressure care largely into the hands of industry.

As the use of support surfaces for preventing and treating pressure sores has become widespread, competition between manufactures has intensified. Marketing methods have become more subtle. Unfortunately, because doctors and nurses have a poor understanding of pressure injuries, manufacturers are able to make recommendations which are seldom challenged. Indeed, many health authorities and nursing schools have come to rely on manufacturers to provide, not only the supports, but a complete package of education and in-service training to go with them. Some firms have even had the temerity to offer to indemnify users if patients get patient sores. This means that they hope to prevent - and heal - sores, but at their own price.

Healthcare dynamics are complicated. Although we like to think that doctors and nurses and manufacturers are primarily interested in preventing pressure sores, this is not necessarily so. The challenges and status of healing sores may be more rewarding. Industry exploits this. It wants to help nurses and patients but also to make money. The latter is essential because otherwise businesses will fail. Thus manufacturers are not greatly interested in preventing sores. If patients develop sores on a 'first line' low pressure supports they can then sell the service more profitable low air loss or alternating pressure mattresses to heal them. They can also recommend that all very ill patients are nursed on 'second line' mattress replacements or even on flotation beds from the start. As rental in the UK of an air fluidised bed is about £70 per day, compared with a purchase price of about £700 for an alternating pressure overlay which is likely to last for about five years, this can make a big difference to hospital budgets. Rental and purchase of pressure relieving equipment is now one of the three top items on the NHS purchasing bill, along with pacemakers and equipment for diabetics. The presence of sores also gives industry the opportunity for developing and marketing a 'bewildering array of complex wound interventions'.³⁶

Sadly, the NHS Centre for Reviews and Dissemination did not help this situation when it published its Effective Healthcare Bulletin in 1996³⁷ in which it concluded that none of the clinical trials which had been carried out up until that time had been sufficiently rigorously controlled to prove that any system of pressure relief was better than another. This has not only discouraged further research but has given manufacturers carte blanche to say what they like about their products because there is no accepted evidence to the contrary. Worst of all, it has prevented nurses who have found particular supports useful in practice, from incorporating this knowledge into training schemes because 'there is no evidence'. As a result, despite a plethora of 'guidelines', training in pressure care in the nursing profession is more confused than it has ever been. Few manuals contain any practical instructions about how to relieve pressure in a vulnerable patient, and least of all about the continually changing equipment which all nurses are expected to use.

Both the medical and nursing professions need to return to the patient. For patients, the primary need is to prevent illness, or, if they are ill, to recover as quickly and safely as possible. Every clinical observation and every strategy must be harnessed to achieve this. Effective antibiotics are prescribed by doctors as first line treatment for sick patients (has penicillin ever been tested in a randomised controlled trial?) so why not effective pressure relieving supports?

References

1-23 can be found with the first part of this essay, on page 21 of the EPUAP Review, Volume 3/1.

24. Gunnewicht BR. Management of pressure sores in a spinal injuries unit. Journal of Wound Care 1996; 5(1): 36-39.
25. Bliss MR. Preventing pressure sores in elderly patients: a comparison of seven mattress overlays. Age and Ageing 1995; 24: 297-302.
26. Ryan TJ. Cellular responses to tissue distortion. In: Bader DL (ed). Pressure sores. Clinical practice and scientific approach. Basingstoke: Macmillan Press 1990: 141-152.
27. Summer WR, Curry P, Haponik EF, Nelson S, Elston R. Continuous mechanical turning of intensive care patients shortens length of stay in diagnostic related groups. Journal of Critical Care 1989; 4: 45-53.
28. Guttman L. The prevention and treatment of pressure sores. In: Kenedi RM, Cowden JM, Scales JT (eds). Bedsore biomechanics. London: Macmillan Press 1976: 153-159.
29. Touch Ross and Company: The costs of pressure sores. Report to the Department of Health December 1993.
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35. Rondorf-Klym LA M, Langemo D. Relationship between body weight, body position, support surface and tissue interface pressure at the sacrum. Decubitus 1993; 6(1): 22-30.
36. Harding K. Challenges for skin and wound care in the New Century. Advances in Skin and Wound Care 2000; 13(5): 212-215.
37. Cullum N, Deeks L, Fletcher A, Long A, Mouneimne H, Sheldon T, Song F. The prevention and treatment of pressure sores. Effective Health Care 1995; 2(1) (Churchill Livingstone).