sábado, 20 de marzo de 2010

Wound healing complications associated with lower limb amputation

Wound healing complications associated with lower limb amputation

The majority of patients undergoing amputation of the lower limb have peripheral vascular disease, often resulting in significant morbidity and mortality. The incidence of amputations is higher in smokers, rises with age and is higher in men than women. Furthermore, people with diabetes form just less than half of all amputees. Consequently, it is not surprising to find that such patient risk factors can result in an array of wound-healing difficulties, thus prolonging debilitation and reducing quality of life. The UK's increasingly ageing population means that more elderly patients will be operated on in the future, thus giving rise to a growing trend in postoperative tissue viability problems where skin fragility and multiple pathologies such as diabetes and peripheral vascular disease co-exist. Hence wound healing complications associated with amputation are becoming more commonplace, requiring sophisticated management strategies to meet the needs of these vulnerable patients. The most important factor in ensuring a successful amputation is the correct choice of amputation site based on assessment of limb perfusion and functional requirements. The following factors will affect the outcome of amputation: the patient's nutritional status, age, tissue perfusion, smoking habits, infection and the presence of co-existing diseases such as anaemia and renal failure. This paper describes a number of problems associated with amputation wound healing, including infection, tissue necrosis, pain, difficulties associated with the surrounding skin, bone erosion, haematoma, oedema and dehiscence/wound breakdown. It draws on the available literature to guide best practice in this complex area of surgical wound care and highlights the importance of multidisciplinary team working.

Amputation is the term given to the severance of a limb, or part of a limb, from the rest of the body . Amputations above or below the knee are termed major. Minor amputations involve partial removal of a foot, including toe or forefoot resections . Amputation is performed on patients with advanced critical limb ischaemia who cannot be treated with reconstructive vascular surgery (to restore blood flow to the leg) or in whom vascular surgery has failed, for patients with diabetic foot infections, extensive venous ulceration or following major trauma .

The lower limb amputee population in England is thought to be around 52,000 . Patients who have undergone lower limb amputation account for 92% of all amputees referred to prosthetics centres in the UK . Significant geographical variation in lower extremity amputation rates has been reported in the UK, with variability in clinical decision-making a likely factor (though further research is required to explore the reasons for this) . The incidence of amputation is higher in smokers (6), rises steeply with age, with most amputations occurring in patients aged more than 60 years, and is higher in men than women . Diabetes is a significant factor in lower-limb amputation . People with diabetes constitute 50% of all major lower limb amputees . Diabetes-related lower extremity amputation rates have been found to be 12.5 to 31.6 times those of patients without diabetes.
Approximately 85-90% of lower limb amputations in the developed world are caused by peripheral vascular disease, with the remaining amputations caused by infection secondary to diabetic foot ulceration. The incidence of lower limb amputation arising from vascular impairment or lower limb ischaemia increased from 56% in 1998/99 to 75% in 2004/05 in the UK . The authors point out that this increase could be attributed to improved data recording from prosthetic centres. Table 1 gives statistics from the Amputee Statisitical Database for 2004¬-2005.
Types of lower limb amputation

Amputation is performed at a number of different levels (see Figure 1). The most common continues to be the trans-tibial level, accounting for almost half of all referrals to the prosthetic services in the UK . Determining the ideal level of amputation for a patient depends on a number of factors. An holistic assessment considers factors such as healing potential, rehabilitation potential, prosthetic considerations, the patient's own wishes, discharge arrangements , and the extent of non-viable tissue on the affected limb . Consideration must be given to knee and hip function and the presence of joint prostheses. The final choice of the level of amputation is considered to be a compromise between ensuring primary wound healing and maximising the patient's function postoperatively.
Wherever possible, patients should be empowered to make an informed decision about the level of amputation. People to involve in this process would be the surgeon, the vascular nurse, who can offer pre-operative counselling, the physiotherapist and possibly an 'expert' patient who has undergone amputation.
All patients undergo a vascular surgical assessment before amputation  , which may incvolve a number of procedures, including transcutaneous oxygen (TcP02) measurements , laser Doppler flowmetry and segmental pressures and ankle brachial pressure indices.
Wound healing complications in the lower limb amputee
Surgical wounds that heal by primary intention are expected to heal successfully without complications . However, there is little evidence to demonstrate that this actually happens in practice. Although wound infection is acknowledged to be a significant problem in surgical wounds, there are anecdotal reports that other complications such as dehiscence, the splitting open of a closed wound, and skin blistering occur, yet these problems do not feature widely in the literature.
It has been estimated that over six million operations were undertaken in the NHS in England and Wales in 1998-99 . However, advances in surgery would suggest that the number of surgical procedures and their resulting wounds are set to increase. The National Institute for Health and Clinical Excellence (NICE) estimates that, based on data from a surgical department of a district general hospital, there may be 21,000 difficult-to-heal surgical wounds per annum in England and Wales (25). NICE acknowledge that this number may be a significant underestimate. The UK has an ageing population, which suggests that an increasing number of elderly patients will be operated on in the future, thus producing a rise in postoperative tissue viability problems where skin fragility and multiple pathologies co-exist. Indeed, both Harding (1993) and Mulder et al (1998) have alluded to the need for awareness of demographic changes in relation to woundcare developments – tissue friability and prolonged wound repair associated with ageing are acknowledged to be key problems .
Within the population of patients with peripheral vascular disease, major lower extremity amputation results in significant perioperative morbidity and mortality. Patients are often extremely debilitated, with multiple co-existing cardiovascular risk factors. The prognosis following amputation is poor: nearly a third of unilateral amputees lose the other limb within three years and half of them will die within five years.
Wound healing complications associated with the stump of an amputee are important because in some cases these determine a patient's ability to walk with a prosthetic limb . One study concerning lower limb amputation found that the commonest stump-related complications were wound infection and poor healing (70%), poorly fashioned stumps (20%) and phantom pain (10%) . The healing rates for below- and above-knee amputations vary considerably. It is thought that a total of 90% of above-knee major amputations heal, 70% primarily, whereas for below-knee amputations, primary healing rates range between 30% and 92%, with a re-amputation rate of up to 30%.
Important factors in healing and outcome of amputation include the patient's nutritional status, age, whether or not the patient smokes, the presence of old potentially infected graft material and the presence of co-existing diseases such as renal failure, diabetes and anaemia . Site selection is considered a crucial factor as healing depends on the adequacy of perfusion. Healing also depends on the technical precision of the surgeon . The type of surgical technique used for below-knee amputation has not been found to have an effect on stump healing, wound infection, re-amputation rate or mobility with a prosthetic limb and is considered to be a matter of surgeon preference . Chalmers and Tambyraja conclude that no system is foolproof in predicting amputation healing .

Wounds associated with amputation of the lower extremity continue to be a challenge. Patients who endure such wounds are often in poor health, with co-existing medical pathologies. Wound healing outcomes for amputees can be improved through multidisciplinary teams working together. Such healthcare professionals need to be equipped with the appropriate knowledge and skills in wound management to meet the needs of this vulnerable patient population. Surgical wound management in the lower extremity amputee has moved into a new era where complications such as infection, tissue necrosis and dehiscence are demanding more sophisticated therapies.
Maria Gabriela Medina Maldonado
C.I. 16779553

No hay comentarios:

Publicar un comentario