The Role of Larval Therapy as an Alternative to Conventional Treatment for Acute or Chronic Wounds - Essay Example

Who was the first man who recognised benefits of using maggots for treatment infected wounds? Ancient Greek? Was it the medicine men of Australian tribes (SMTL, 2003)? Or the great French surgeon Ambroise Paré? We can only suppose – only few historical references were dedicated to this issue. But what is the reality and undoubted fact it is increased interest to the alternative approaches in the wound healing. British researchers and health care patricians participate very actively in the process of developing this “new old” method of wound debridement. An official history of larval therapy started in the early 1930s when American surgeon William Baer introduced the maggot therapy into the clinical practice (SMTL, 2003). He and his followers used sterile maggots and proved the efficiency of larval therapy of purulent surgical infection. But in spite of the huge amounts of articles published before the Second World War we cannot use them for current analysis of evidence. The medicine passed long distance since the first attempts to manage heavy wounds were made and simple methods of maggot sterilization were introduced. When era of antibiotics started medical community forgot about larvae. When surgeons faced the problem of antibiotic resistance and nosocomial infections they thinks were turned back to the larval therapy. But is this medical technology evidence based? To answer this question there was performed information search in the modern electronic databases Medline, Ovid, Direct Science and CIHAHL. The used keywords are presented as follows: “larval therapy”, “wound healing”, “maggot”, and “evidence-based practice”. Appropriate Boolean operands “OR”, “AND” and “NOR” were used also. To optimise search results and increase their relevance and pertinence the MeSH (Medical Subject Headings) thesaurus was applied, e.g. subheadings “Wound Healing/physiology"[MeSH] and "Larva"[MeSH]. The preferences were given to the systematic reviews, meta-analyses and primary data of randomised clinical trials, i.e. to the information sources of the I level of evidence, as well as to the clinical guidelines based on the best evidence. Evidence based practice can be determined as the concept of integrating the most current scientific evidence in making decisions about the delivery of health care services. There are several levels of evidence depending on the qualitative characteristics and the design of study. The highest level of evidence is represented by meta-analyses and/or systematic reviews. They are developed by synthesizing of the experience obtained during randomized controlled clinical trials. Unfortunately, their use in surgery and related fields of medicine is restricted. The second level of evidence is presented by cohort studies (see fig. 1 in the Appendix). Prior to discuss pro- et contra of larval therapy let’s do short overview of the pathophysiology of wound healing. There are two types of wound healing – healing by primary and secondary intention (Bryant, 2000; Sedlarick, 2001). The distinction between these two variant of healing can be described by some factors including the peculiarities of blood supply, immune response and presence of infection. If less volume of tissues is damaged than the conditions for wound healing are more favourable. Generally, the hack is healing faster than the avulsed wound or chopped wound. By the expert opinion (Lewis, 2001) “the best prognosis for successful wound healing [i.e. proceeding by first intention healing] is found with smooth, closely abutting incision wounds without substantial tissue loss or presence of foreign bodies, in well-vascularised areas of the organism” (p. 1). If listed conditions are not present than wound healing by secondary intention will occur. Because of the significant tissue defect the developing and growth of granulation tissue is necessary. Of course, the process of healing by secondary intention is slower and could require special measures including the debridement – the removal of devitalised, necrotic tissue or fibrin from a wound. Another element, which is important for understanding the pathophysiology of wound healing, is inflammation. This phase of wound healing is characterized by Galen’s pentad: redness, heat, swelling, pain, and loss of function. The complicate chain of biochemical reactions including the activation of kallikrein-kinins system, the pathways of arachidonic acid transformation, the coagulation cascade, which maintains the inflammatory phases (Scholar & Stadelmann, 2003). There are three distinct phases of inflammation: alteration, exudation and proliferation. In the initial inflammatory phase platelets aggregation stimulates releasing proinflammatory active substances (e.g. tissue growth factor-beta (TGF-beta) and platelet-derived growth factor (PDGF). After this plasma exudation and leukocytaric infiltration occurs and the production of fibroblasts is stimulated. In the proliferative phase there are granulations form and the process of epithelialization begins. The key role in this phase is played by fibroblasts, which maintain processes of the proliferation and synthesis of collagen. Finally defect of tissue is filled out and wound is healed. The distinction between acute and chronic wounds is grounded on the efficacy of proliferation and scar maturation. If wound proceeds successfully through reparative process and anatomic and functional integrity of injured tissues is restored than wound can be determined as an acute one. But if the processes of healing were failed in any stage than term “chronic wound” is used for characterising. Of course, in such cases the healing process is prolonged and incomplete. What role of maggots in wound healing? Devitalised, necrotic tissue (detritus) and fibrin in presence of pathogens became an important risk factor. Detritus and bacteria are the sources of toxic substances which suppress normal healing and result in chronization of wounds. When surgeons use differne techniques of the debridement (classical dressings, osmoactive solutions, antibiotics, surgical interventions etc) they eliminate the threat of the dangerous complications and improve prognosis. Unfortunately, sometimes the efforts of specialists are not enough effective (Heaas, 2002). Reintroducing of larval therapy gives the alternative to existing methods of wound healing. Dr. Thomas S. from Princess of Wales Hospital (Bridgend, UK) describes (2000) the sterile medicinal maggots as "living chemical factories" (p. 104). The mechanisms of wound debriding are still unclear but some investigators (Beasley & Hirst, 2004; Horobin et al., 2003; Thomas et al., 2000, 2001; Sherman et al., 2000, 2001, 2002, 2003; Prete P., 1997 etc) consider that the maggots can produce proteolytic enzymes that destroy necrotic masses, can consume exudates containing bacteria and change wound pH to alkaline reaction which is unfavourable for bacteria (due to secreting allantoin, ammonia and calcium carbonate by alive maggots). It was shown in in-vitro and in-vivo studies that maggots can eradicate or inhibit the growth of a range of pathogenic bacteria (Steenvorde & Jukema, 2004; Wollina et al., 2000), especially of gram-positive ones (e.g. Staphylococcus aureus and Streptococci) but can be useful also for the treatment of wounds infected by gram-negative bacteria (e.g. Pseudomonas aeruginosum, Escherichia coli or Proteus vulgaris). Generally, the benefits of medicinal maggots for wounds debriding could be explained by following hypotheses: Dissolving necrotic and infected tissues Disinfecting wound, by killing bacteria Stimulating wound healing By the assessment of the specialists there are more than 3,000 followers of larval therapy worldwide. Of course, maggots cannot replace conventional therapy completely but every year the number of patients treated with the use of bio-therapeutic technologies is increased (Thomas et al., 2000, 2001). These circumstance made to be possible the official accepting of larval therapy by the Food and Drug Administration (USA) and the British National Health Service (UK) in 2004 (Thomas et al., 2005). The last event is very important for developing larval therapy in the Great Britain. Actually, British doctors got official permission to prescribe maggot therapy if their patients require it. It means that patients could get care they need on the sites without referring to the regional specialized hospitals. The technique of the application of maggot dressings is very simple, thus this method could be used even in small health facilities or in outpatient institutions. The maggot therapy is well-controlled method; consequently the risk of complications is minimal. If at the beginning of the use of larval therapy the risk of infectious complications was significant than this method is very safe in nowadays. Usually they put cage-like dressing over the wound for 2-4 days (Thomas et al., 2005). There are two variants of the intervention: the maggots may be allowed to move freely within the cage, with the wound floor acting as the bottom of the cage or the maggots may be contained within a sealed pouch, placed on top of the wound. The modern protocols of the use of maggot therapy include following indications: for treatment of chronic and infected wounds, i.e. pressure sores, leg ulcers, diabetic foot ulcers, traumatic wounds and lacerations, amputation sites, dehisced surgical wounds, infected wounds of all types that have failed to respond to conventional treatments etc (Jones & Thomas, 2000). Because maggots need oxygen for normal vital functions than only brightly open wounds can be treated successfully with biosurgery. The contraindications for larval therapy are presented by such conditions like the wounds having insufficient blood supply (e.g. due to arterial obliterations), gangrenous wounds, fistulae, penetrating wounds, bleeding wounds and wounds located close to major blood vessels or nerves. There is absolutely prohibited to use non-sterile maggots for larval therapy of wounds (Thomas et al., 2005). The cases of allergy or idiosyncrasy to the larval excreta were not reported yet, but theoretically, these conditions should be considered as contraindications too, and caution should be exercised to this issue. Allergies could occur not only to the native proteins of maggots (Thomas et al., 1996) but also to soybean and ovalbumin using for maggot breeding. The standard procedure of larval therapy includes the use of two-layered cage-like dressing. After the pad is affixed to the surrounding healthy skin than young, sterile medicinal maggots are introduced into the wound (Wollina U. et al. (2000). The bottom layer of this pad is then covered by a fine chiffon or nylon net which permits oxygen to reach the maggots and allows to inspect the wound as well as to facilitate drainage of exudates. This dressing is usually left in wound for 2-3 days until the maggots will be almost fully grown. To debride the wound completely there are usually necessary several weeks, but the duration of treatment depends on the size of the wound and the number of maggots applied to wound surface. Nowadays larval therapy is considered to be an effective medical intervention, which can be used for debridement, disinfection and stimulation of healing especially in chronic wounds of skin, subcutaneous tissue and osteomyelitis. It can easily be combined with other techniques. Only a few side effects were reported in the recent publications (Wollina et al., 2000; Thomas S., 2001) e.g. minor discomfort because of the movement of maggots on the wound margins in hypochondriac patients, and malodour during the first dressing change. The numerous articles were published in the last decade (see References list) but only a few of them have high rate of clinical evidence. After specialized search in Medline (PubMed database) using the tool “Clinical queries” there were only 3 items retrieved for the query “larval therapy” AND “wound healing” systematic[sb]. This fact can be explained by the difficulties in organizing randomized controlled trials (e.g. ethical issues). Otherwise the general quantity of articles related to the problems of maggot therapy, which were published in the world after 1995, is more than 500 items. Systematic review prepared by Smith (2002) was dedicated to the problem of the treatment of diabetic foot ulcerations. There was not enough evidence to get conclusion about any significant benefits of larval therapy of diabetic foot ulcers. Non-peer-reviewed article prepared by Raynor, Dumville & Cullum (2004) reported the preliminary results of the VenUS II trial which is the first large prospective clinical study to investigate the effect of larval therapy on the healing of leg ulcers. This trial is aimed to compare the clinical and cost effectiveness of two loose and bagged types of larval therapy with a standard debridement intervention (hydrogel). There were studied time of the debridement, wound microbiology, cost of treatment and health-related quality of life. Unfortunately this trial is not finished yet and its findings will be reported only in the next year. A critical review by Leach (2004) is dedicated to the use of “natural” therapy in clinical surgery for healing wounds. He wrote about the deficiency of well-designed clinical trials and necessity of further researches on the cost-effectiveness of larval therapy methods. MacDougall & Rodgers (2004) form Clydebank Health Centre in Glasgow reported a case study related to the used of larval therapy by district nurses. This ase study is presented of a patient with a wound in anterior tibial region occurred after fasciotomy. This chronic wound was treated by routine methods without success before to apply the larval therapy. Authors consider that sterile maggots are the effective and safe debriders of wound tissue for wound bed preparation. Unfortunately the level of evidence of this research is low. Results of another case report study was recently published by Tanyuksel et al. (2005). The authors examined the efficacy of maggot therapy in the debridement of chronic wounds in a military hospital. The larval therapy was applied for 1-9 days to 7 male and 4 female patients having chronic wounds. Complete debridement of wound was achieved in the absolute majority of patients. Success in the use of maggots for therapy of necrotizing fasciitis of the neck was achieved by the team from Germany (Preuss, Stenzel & Esriti, 2004). The authors used standard set of sterile medicinal maggots produced by the company BioMonde. They found that the use of sterile maggots for wound is an efficient alternative method for wound debridement. The significant improvement of the course of disease was obtained on 3rd-4th day of treatment by maggots. An attempt to assess the cost-effectiveness of larval therapy was made by Thomas & Jones (2001). These researchers compared the published evidence on the clinical and economical effectiveness of larval therapy with the conventional dressings using to promote autolytic wound debridement. By their opinion the benefits of larval therapy include high cost-effectiveness of the treatment. The similar point of view was expressed by Richardson (2004). He sees benefits of the use of larval therapy in wound care in the possibility to use this alternative method of the treatment for eliminating methicillin-resistant strains of Staphylococcus aureus. This ideas are very close to the Thomas’ opinion (2000). This British surgeon is one of the world leaders in the field of clinical researches related to the use of larval therapy. Steenvoorde & Jukema (2004) reported the results of clinical trial on the antimicrobial activity of maggots. Their in-vivo results showed high effectiveness of the maggot therapy in the treatment of surgical infection. It was shown that maggot therapy is more effective in the treatment of infection caused by gram-positive microflora. On the contrary, the gram-negative bacteria were not so sensitive to the larval therapy. Authors proposed to use a higher number of maggots for treatment of gram-negative infected wounds. Sherman’s (2003) report about the results of his prospective trial of conventional wound care followed by larval therapy contains data that the use of maggots is more efficient than conventional treatment by hydrogel. In his small randomised controlled trial Mumcuoglu (200s) found also that maggot therapy debrided the venous ulcers more quickly and effectively than standard hydrogel dressings. He also assessed the economic benefits of the implementation of the larval therapy. Wolff & Hansson (2003) investigated the effects of larval therapy on wounds in the study of 74 patients with necrotic or sloughed chronic ulcers of different aetiologies. They found that maggot therapy was effective in 86% of the cases, and that the failure of wound debriding was related to larval death. The authors consider that larval therapy is “effective for debriding ulcers, easy to use and well accepted by the patients” (p. 134). The positive patients perception of larval therapy was reported also by Kitching M. (2004). She considers that the relationships between nurse and patient are a significant factor in acceptance of this type of wound treatment. Today maggot therapy is still unconventional method. Some health providers and institution could accept these methods, some of them can not. The problem that the rule of “golden standard” may not be applied for the researches in the field of clinical application of larval therapy. Medical community read reviews based on the huge amount of case reports (III level of evidence). There are no randomised clinical trials, no cohort studies and, consequently, no meta-analyses and systematic reviews. The intuition is “bad” counsellor for advanced clinical practice. Probably the best approach is evidence based practice which can be defines as a process by which nurses make clinical decisions using the best available research evidence, their clinical expertise and patient preferences, in the context of available resources. Evidence-based practice is designed to be a systematic means of combating the biases that arise from uninformed decision-making. Consequently, for successful decision making medical community should have access to the researches of the highest possible evidence. An active participation of the members of multidisciplinary teams will be helpful in spreading positive experience and best clinical practice in the national health care system. General approach of nurse practitioner could be described as follows. If the patient suffered of serious wound that is unresponsive for conventional therapy than the alternative care should be chosen. Because many types of wounds cannot be treated with maggots nurse should assess the current state of wound and patient. An important question, which should be answered – the optimum number of maggots using for treatment. After larval therapy was started the nurse should provide monitoring of exudation. For example during the first dressing the excessive exudation results in increasing of fetid odour. Some patients could feel mild pain during maggot therapy. In such cases the maggots can be removed prior to usual term (3rd day). The removal of larvae from a wound is generally easier to do simultaneously with the removal of hydrocolloid and net. After all maggots were removed than reassessment of the wound may be necessary. Clinical decision is done between two alternatives – continuing larval therapy or change it for conventional therapy. In any case patient’s interests have the highest priority. References: 1. Beasley WD, Hirst G. (2004) Making a meal of MRSA-the role of biosurgery in hospital-acquired infection. J Hosp Infect. Vol. 56 Issue 1 pp. 6-9. 2. Bryant R. (2000) Acute & Chronic Wounds: Nursing Management C.V. Mosby; 2nd edition 558 p. 3. Heaas C. (2002) Clinical Guide to Wound Care Lippincott Williams & Wilkins; 4th Spiral edition. 487 p. 4. Horobin AJ et al. (2003) Maggots and wound healing: an investigation of the effects of secretions from Lucilia sericata larvae upon interactions between human dermal fibroblasts and extracellular matrix components. Br J Dermatol. Vol. 148 Issue 5 pp. 923-933. 5. Husain ZS & Fallat LM. (2003) Maggot therapy for wound debridement in a traumatic foot-degloving injury: a case report. J Foot Ankle Surg. Vol. 42 Issue 6 pp. 371-376. 6. Jones M. & Thomas S. (2000) Larval therapy. Nurs Stand. Vol. 14 pp. 47-51. 7. Kitching M. (2004) Patients perceptions and experiences of larval therapy. J Wound Care. Vol. 13 Issue 1 pp. 25-29. 8. Leach MJ. (2004) A critical review of natural therapies in wound management. Ostomy Wound Manage. Vol. 50 Issue 2 pp. 36-40 9. Lewis R. et al. (2001) A rapid and systematic review of the clinical effectiveness and cost-effectiveness of debriding agents in treating surgical wounds healing by secondary intention. Health Technology Assessment Vol. 5: No. 14 (Available at the web-site http://www.ncchta.org/execsumm/summ514.htm on 21.05.2005) 10. MacDougall KM & Rodgers FR. (2004) A case study using larval therapy in the community setting. Br J Nurs. Vol. 13 Issue 5 pp. 255-260. 11. Mumcuoglu KY. (2001) Clinical applications for maggots in wound care. Am J Clin Dermatol. Vol. 2 pp. 219-227. 12. Prete P. (1997) Growth effects of Phaenicia sericata larval extracts on fibroblasts: Mechanism for wound healing by maggot therapy. Life Sciences, Vol. 60, Issue 8, pp. 505-510 13. Preuss SF, Stenzel MJ, Esriti A. (2004) The successful use of maggots in necrotizing fasciitis of the neck: a case report. Head Neck. Vol. 26 Issue 8 pp. 747-750. 14. Raynor P, Dumville J, Cullum N. (2004) A new clinical trial of the effect of larval therapy. J Tissue Viability. Vol. 14 Issue 3 pp. 104-105. 15. Richardson M. (2004) The benefits of larval therapy in wound care. Nurs Stand. Vol. 19 Issue 7 pp. 70-72 16. Scholar A. & Stadelmann W. (2003) Wound Healing, Chronic Wounds. (Available at the web-site http://www.emedicine.com/plastic/topic477.htm on 20.05.2005) 17. Sealby N. (2004) The use of maggot therapy in the treatment of a malignant foot wound. Br J Community Nurs. Vol. 9 Issue 3 S. 16-19. 18. Sedlarik, K. (2001) The processes of wound healing. (Available at the web-site http://www.hartmann-online.de/english/produkte/wundbehandlung/wundforum/default.htm on 20.05.2005) 19. Semple L. (2003) Use of larval therapy to treat a diabetic patients pressure ulcer. Br J Nurs. Vol. 12 Suppl. 15 S.6-13. 20. Sherman RA et al. (2001) Maggot debridement therapy in outpatients. Arch Phys Med Rehabil. Vol. 82 pp.1226-1229. 21. Sherman RA, Hall MJ, Thomas S. (2000) Medicinal maggots: an ancient remedy for some contemporary afflictions. Annu Rev Entomol. Vol. 45 pp. 55-81. 22. Sherman RA & Shimoda KJ. (2004) Presurgical maggot debridement of soft tissue wounds is associated with decreased rates of postoperative infection. Clin Infect Dis. Vol. 39 pp. 1067-1070. 23. Sherman RA. (2002) Maggot therapy for foot and leg wounds. Lower Extremity Wounds. Vol. 1 pp. 135-142. 24. Sherman RA. (2003) Maggot therapy for treating diabetic foot ulcers unresponsive to conventional therapy. Diabetes Care. Vol. 26 Issue 2 pp. 446-451. 25. Sherman RA. (2000) Maggot therapy - The last five years. Eur Tissue Repair Soc. Vol. 7 pp. 97-98. 26. Smith J. (2002) Debridement of diabetic foot ulcers. Cochrane Database Syst Rev. Issue 4 27. SMTL (2003) History of Maggot Therapy. (Available at the web-site http://www.larve.com/maggot_manual/docs/history.html on 19.05.2005) 28. Steenvoorde P. & Jukema GN. (2004) The antimicrobial activity of maggots: in-vivo results. J Tissue Viability. Vol. 14 Issue 3 pp. 97-101. 29. Tanyuksel M et al. (2005) Maggot debridement therapy in the treatment of chronic wounds in a military hospital setup in Turkey. Dermatology. Vol. 210 Issue 2 pp. 115-118. 30. Thomas S. et al. (1996). Using larvae in modern wound management. J Wound Care. Vol. 5 pp. 60-69. 31. Thomas S. & Jones M. (2001) Wound debridement: evaluating the costs. Nurs Stand. Vol. 15 Issue 22 pp. 59-61. 32. Thomas et al. (2005) Protocol for the use of sterile maggots in wound management. Bridgend, Wales, UK. 12 p. 33. Thomas S. & Jones M. (2000) Maggots can benefit patients with MRSA. Practice Nurse Vol. 20 Issue 2 pp. 101-104. 34. Wolff H. & Hansson C. (2003) Larval therapy--an effective method of ulcer debridement. Clin Exp Dermatol. Vol. 28 Issue 2 pp. 134-137. 35. Wollina U. et al. (2000) Biosurgery in wound healing--the renaissance of maggot therapy. J Eur Acad Dermatol Venereol. Vol. 14 pp. 285-289. Appendix: Figure 1. Pyramid of clinical evidence. Read More