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IL DEBRIDEMENT-CONOSCENZE ATTUALI E RICERCA

Introduction

Debridement is defined as the removal of dead/or necrotic tissue and foreign material from a wound (Kennedy and Tritch, 1997). Arnold (1995) reported that the presence of devitalized tissue inhibits healing in several ways: 1) it demands that the body carry out autologous debridement; 2) it facilitates infection/proliferation of bacteria which produce ‘toxins’ competing for oxygen and nutrients; 3) it increases the expression of inflammatory cytokines and proteases, which may interfere with the healing process. Slough and necrotic tissue come in a wide variety of forms, ranging from hard, black/brown, necrotic eschar to white/yellow, soft slough. Debridement of devitalised necrotic tissue  surgically, at the bedside or in the theatre;§can be achieved in several ways:   bio-surgically, using§ mechanically, scrabbing, or with wet-to-dry gauze; §  chemically, with solutions such as hypochlorites or Betadine;§maggot therapy;   autolytically, using§ enzymatically, with products such as Varidase or Elase; § dressings and gels.

Debridement in the diabetic foot ulcer

A distinction should be made with regard to aetiology: i.e. whether the cause is ischaemia or neuropathy (the signs and symptoms of either neuropathy or ischaemia may predominate), both of which set the scene for pressure necrosis, ulceration, infection, and gangrene. Treatment will differ accordingly. Another distinction exists between superficial debridement and deep debridement. Sage (1994) distinguishes between these two types of debridement when treating infection. Examples of infections that only require superficial debridement are: plantar keratosis, calluses, or chronic digital corns. Deep debridement is needed when abscesses and deep fascia are involved. A further distinction exists between sharp debridement and surgical debridement. Surgical debridement is deep debridement which at times may be carried out in theatre with general anaesthesia. Debridement can be carried out with scissors or scalpel, and with blade or rong when debriding bone.

The ischemic foot

Elkeles R. and Wolfe J. (1991) and Levin (1996) found that ischaemia in a diabetic foot was caused by: 1) atherosclerosis, 2) formation of microthrombi due to infection resulting in gangrene, and 3) cholesterol emboli. Signs of decreased circulation are usually visible. There may be small pale punched-out ulcers over pressure points and patches of gangrenous skin at the tips of the toes. Bale (1997), Jones (1998), and Apelqvist et al (1994) specified that it may not always be appropriate to debride necrotic tissue. A gangrenous toe, for example, may be best left to “fall off” naturally. Where there is the suspicion that necrosis may be caused by vascular disease, a vascular surgeon should be consulted. Logerfo et al (1992) reported that part of their protocol was to investigate all diabetic patients for ischaemia. The goal was to restore perfusion. Wagner (1984) found that when some portions of the grade IV foot were gangrenous (toe/toes, forefoot, or heel), it could be possible to cut away the gangrenous tissue or lesions at the tips of the toes. In such cases, only gangrenous tissue is cut and the skin contracts well over the end. The bone must be cut with a rongeur below the surface for the skin to close over the area.

It is evident that the problems encountered when treating diabetic ulcers with a predominance of vascular disease are different from those met with in the neuropathic ulcer, because unless blood supply is restored to the wound, healing cannot take place. The responsibility for caring for such ulcers falls to specialised clinicians such as vascular surgeons. Once revascularization has been achieved, the same wound care principles apply as in the case of the neuropathic ulcer.

The neuropathic foot

Elkeles and Wolfe (1991) reported that peripheral neuropathy was the most important factor in the development of foot ulcers. Reduction or loss of sensation was found to result in the inability to perceive damage induced by mechanical trauma. Pressure on the plantar skin of the foot is thereby greater and calluses develop under the heads of one or more metatarsals. (A callus is defined as an excessive formation of keratin caused by tissue subjected to stress/pressure.) A cavity becomes filled with plasma, blood accumulates, and eventually ruptures onto the skin surface. The ulcerated opening may be small compared with the larger lesion beneath. Booth (1997) and many of his colleagues are of the opinion that sharp debridement of a callus with a scalpel is the first line of treatment.

Infection in the diabetic foot

Elkeles and Wolf (1991) pointed out that in addition to having problems with pressure, poor perfusion, and infection, diabetic patients suffer from impaired healing. Their high tissue glucose concentrations impedes the activity of leukocytes and macrophages, which are unable to produce enough fibroblasts to synthesise the collagen. Often the depth of the infected pedal ulcers is masked by infected, necrotic tissue, and gentle probing is necessary to determine whether the ulcer extends to underlying bone (Grayson et al, 1995). Infection in the diabetic foot ulcer can spread very rapidly, leading to amputation – as reported by Foster (1996) and Frykberg (1991) – and therefore it is generally agreed that when infection or suspicion of infection exists, aggressive debridement should be performed. “Infected ulcers, regardless of their underlying aetiology, require prompt surgical debridement and antibiotic therapy” – Sage (1994). Levin (1996), Laing (1994), Eyser (1992), and Bisà and Poli (1993) all advocate that in patients with undrained pus or extensive tissue necrosis, incision, drainage, debridement and occasionally partial forefoot open amputation must be performed.

As Rosenblum B. et al (1994) noted, there are no current studies that compare the success of surgical versus nonsurgical debridement in the diabetic foot. Piaggesi (1998) supported this view and noted that comparative randomised trials were still lacking. In addition, Arnold (1995) points out that it is extremely difficult to define ‘adequate’ debridement. How extensive should the debridement be? This poses problems for surgical training and research.

In a prospective randomised study, Piaggesi (1998) attempted to evaluate the efficacy and safety of superficial debridement against deep debridement in 41 diabetic patients with neuropathic ulcers. Group A availed of conventional management: initial debridement of lesions and elimination of surrounding hyperkeratosis; the wound was then dressed with saline gauze. Patients were advised to change the dressing every 24 hours. Group B underwent surgical excision of the ulcer, which consisted of the removal of the ulcer through conic ulcerectomy. This process removes both the walls and the bottom of the lesion; in cases where bone segments may interfere with the closure of the wound margins, their debridement or removal was performed with scalpels or a rong. The objectives were to evaluate a) the healing rate in a 6-month follow-up period; b) the duration of healing time; c) the prevalence of recurrence and of infective complications. General therapy for group B patients differed from group A in that systemic parenteral wide-spectrum antibiotics were given 5 days after surgery. The author’s conclusion was that although the majority of neuropathic foot ulcers in this study did heal with the conventional treatment as well, the longer healing time and the higher incidence of infections in this group of patients made such treatment less convenient and less safe than the surgical approach. One could question why the author chose saline gauze as the dressing of choice. Saline gauze dressing tends to dry out, adhere to the wound and retard healing, according to Madden et al (1989) and Alvarez (1989); also, changing the saline gauze once in 24 hours may not be sufficient. Furthermore, it is not clear why antibiotic therapy was administered only to group B, considering the high rate of infection in Group A (the group receiving conservative treatment).

Georges Ha Van (1996) carried out an investigation on 67 diabetic patients with foot ulcers with osteomyelitis once vascular involvement (requiring reconstruction) had been excluded. He compared medical treatment – which was composed of antibiotic therapy, offloading and wound care (the author does not specify what this consisted of, other than topical metranidazol or clavulanic acid when peripheral vascular disease was present) – for one group from 1986 to 1993 versus medical treatment using conservative orthopaedic surgery in another group from 1993 to 1995. The latter treatment consisted of limited resectioning of the infected part of the phalanx or the metatarsal bone under the wound. The healing rate in the surgical treatment group was 78% as opposed to 57% in the medical treatment stand-alone group. It would appear from this study that the author does not consider topical dressings to have made any contribution with regard to healing as he does not even specify which dressings the patients availed of. Donaghue (1998), on the other hand, compared two topical dressings – saline gauze dressing against an alginate dressing – in 75 diabetic patients and found a better outcome in the patients availing of the alginate dressing: 48% complete healing versus 36%.

In 1996, Steed carried out a study examining the effect that extensive debridement of diabetic foot ulcers had on the healing rate. Some 118 patients from 10 centres were allocated to two groups, one treated with topical rhPDGF and the other with a placebo. A better response rate was achieved with more frequent debridement, independent of the treatment group – although the group that received rhPDGF had a better healing rate. In the patients receiving moderate debridement there was no obvious correlation between frequency of debridement rate and healing rate. The influence of debridement was evaluated by reviewing patient's records. One of the author’s conclusions was that surgical debridement was an essential adjunct in the care of patients with diabetic foot ulcers. However, the fact remains that we do not know the exact extent of debridement required; nor is it clear why more frequent debridement produced outcomes that differed from those achieved with less frequent debridement.

Salaman J.H. (1995) reported that the length of time needed to achieve debridement was an important factor in the choice of the debridement method: the more rapid method should always be considered before the slower. The time required for conservative debridement is 14-28 days, according to Collin et al (1996), Flanagan(1995) and Pastre et al (1996), therefore this method would be too slow an option as a stand-alone treatment for debridement in a foot with a high risk of infection. Correct assessment is therefore of extreme importance not only in establishing the aetiology, but also in evaluating whether or not we are dealing with an unhealing ulcer.

Goode (1995) advocates conservative debridement in patients who cannot tolerate surgery. The available literature describes anecdotal and case reports of conservative debridement in special cases. Sherman (1995) advocated maggot therapy in patients who could not undergo surgical debridement or pre-surgical debridement. Thomas (1996) describes the case of an infected diabetic ulcer in which the surgeon was hesitant to do surgical debridement and which was successfully treated with larvae therapy. Hyams (1995) describes the conservative debridement of an extensive infected diabetic ulcer caused by pressure. The patient was 92 years of age and living in a psycho-geriatric institution. The vascular surgeon hesitated to perform an amputation on the patient and, recommended soaks with deking solution; however, the nurses continued to use autolytic debridement. The patient died shortly afterwards from other complications.

It is clear that many factors must be taken into consideration and each case must be analysed individually. In diabetic patients where vascular intervention is no longer an option, either due to failure of reconstructive surgery or for other reasons, in the presence of non-viable tissue it may be decided to avail of conservative debridement. Westerhof (1992) reports on two such cases. However even conservative debridement has generated considerable controversy. Due to fear of infection, clinicians use soaks with deking solution or Betadine in spite of the fact that they are known to have damaging effects. Laing (1994) reported that there is an ongoing debate over the timing of local foot procedures after revascularization of non-healing foot ulcers. Deeper ulcers, especially those with infected bone, are best treated with local resection, while superficial ulcers may heal with conservative care once perfusion to the foot has been restored. Unfortunately, there are no current studies that compare the success of surgical versus nonsurgical management of these problems. “Each approach has been reported to be successful in capable hands”.

Legal issues

There is often an overlap of roles in the care of patients with diabetic ulcers and the question remains as to who should carry out the debridement. An overlap exists between doctors, physical therapists, podiatrists and nurses. There is no doubt that it is within the scope of practice of doctors and it would seem that it is also within the scope of practice of podiatrists to carry out sharp/surgical debridement – Knowles et al (1996) and Tyrrell (1995). However, it is not clear whether it is within the scope of practice of nurses or physical therapists. Historically, the role of nurses has changed and evolved and has become more complex; therefore according to some State regulation in the U.S.A., for example, the nurse may perform complex procedures as long as they are delegated by the doctor and as long as the nurse has the skills and education to perform them. As there are no international standards, the legal issues remain unsettled and will become more complex where these issues are not addressed. Therefore nurses must abide by the rules and regulations of the specific local area in which they are practising. In a survey (Fowler, 1997) of 49 States carried out in the U.S.A. as to whether it was the role of nurses to perform instrument sharp debridement, 30 answered ‘yes’. Three of the States specified that it was an overlapping area and stated that the nurses that did it required special preparation and should have the written consent and delegation of a doctor. Are nurses legally covered to carry out surgical debridement? How extensive is the debridement that they can do? And in the event of bleeding in a patient’s home care, can they cope with the complications? These questions remain unanswered. One other important consideration however should be made – as Zederfelt (1995) points out – and that is that surgical or sharp debridement may often be missed out on because wound care is provided by personnel who have not had sufficient surgical training or have a limited knowledge of anatomy.

Conclusion

Many clinicians advocate aggressive surgical debridement as part of the treatment for neuropathic foot ulcers once significant vascular involvement has been excluded or addressed: Wagner (1984), Knowles (1997), Laing (1994), Steed (1996), Piaggesi (1998), Levin (1996). Attempts to try and save the limb from amputation are a main concern in treating such patients. It would appear from reviewing the literature that sharp/surgical debridement is the most accepted method of debridement and is based on long clinical experience and some evidence derived from research. However, since research on conservative debridement in diabetic foot ulcers is lacking, against what does surgical debridement measure itself? Some attempts have, in any event, been made to explain why surgical/sharp debridement is efficient.

Arnolds (1995) states that “surgical debridement results in platelet adhesion and degranulation, which may in itself release growth factors, transforming a chronic wound into an acute wound”. Steed (1996) says that even when granulation tissue may seem “normal” (in the chronic wound), fibroblasts and other cells may become senescent and produce less cytokines and collagen. Piaggesi (1998) found that there was a correlation between the conservative approach and variables such as ulcer size, duration of the ulcer, position, patient compliance, frequency of dressing changes, and occurrence of systemic infections, and noted that with deep debridement these variables were eliminated. He also hypothesised that one possible contributor to the success of deep surgical debridement, in his study, was the reduced need for compliance, through self-care. This observation indicates that there are important aspects beyond the purely physiological to take into account in measuring outcomes from methods of debridement.

Many clinical trials on various aspects of diabetes have been published, but none comparing conservative non-surgical debridement against sharp/surgical debridement in diabetic foot ulcers (Rosenblum et al, 1994). Studies on surgical debridement in the treatment of diabetic ulcers are few. Some are based on historical data (Ha Van) or result from studies in which debridement was not the aim of the study, such as Steed’s study (using information from patients records); in other cases, studies were imperfectly designed because it was difficult to measure the exact effect debridement had on healing or for other reasons.

However, the extent of debridement required and its frequency still need to be agreed upon. As Arnold (1995) points out, methods of standardisation may need to be defined.

Conservative debridement is practised for various reasons, such as in cases where doctors hesitate to fully debride necrotic tissue due to general pessimism about salvaging the leg in patients with diabetes, as Keyser (1992) points out; or when surgical debridement is not an option, as Westerhof (1992) points out; or for various other reasons, such as lack of knowledge or resources. However, one should remember that there is no research upon which to base this practice and careful attention to fast-spreading infection and deterioration should be given.

Nevertheless, there is also controversy over the best conservative debridement. Conservative debridement may well have a place as an adjunct therapy to surgical debridement (Ricci, 1997).

Another controversy surrounds the legal aspects involved when nurses, even specialised foot nurses, carry out debridement. The nurse in question will be held legally accountable and would have to prove that he/she avails of specialised training to justify the undertakings. There is an enormous difference from one country to the next as to what nurses are allowed to do. Clear definitions are lacking with respect to laws, accountability and the preparation nurses need in order to carry out deep debridement.

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