Technology update The use of larval therapy in modern wound care


PRACTICAL TIPS


n Before the application of larvae, the patient’s verbal consent should be gained and all aspects of the treatment fully explained. This should include informing them that live larvae will be applied, how they work and the possibility of an elevation in pain levels.


n Dry necrotic wounds are generally not suitable for larval therapy as they require softening first. Larvae are unable to begin any mechanical breakdown if the wound surface is hard and dry[11]


.


n Larvae should not be applied to patients with clotting disorders and those receiving anticoagulant therapy, unless they are under constant medical supervision in a healthcare facility. Rapid debridement through larval therapy can increase bleeding in patients who have problems with blood clotting once the wound bed is exposed, due to small vessels being damaged by the actions of the larvae [3]


. n Pain levels should be considered, and analgesia prescribed, on a regular basis and before dressing changes. Larval


secretions can change the pH level within the wound and this may affect pain receptors in proximal healthy tissue [12]


. The most commonly reported minor effects are transient pyrexia and increased pain. The aetiology of the pyrexia has never been satisfactorily explained[13]


.


n The wound should be thoroughly irrigated with saline before the application of larvae to ensure any previous autolytic applications have been completely removed[14]


.


n Monitor the surrounding skin as the enzymes produced by the larvae can cause excoriation if they are in contact with skin around the margin of the wound. This can be avoided by protecting the surrounding skin — with a barrier film or hydrocolloid dressing — before application.


References


7. Parnes A, Lagan KM. Larval therapy in wound management: a review. Int J Clin Pract 2007; 61(3): 488–93.


8. Amit Gupta MS. A review of the use of larvae in wound therapy. Ann Plast Surg 2008; 60(2): 224–27.


subsequently ingest[15] . The mandibles and


spicule (hook-like appendages that dorsally project from each body segment of the larvae) stimulate the wound tissue as the larvae move across it distributing digestive enzymes[10]


. The commonest uses of larval therapy are


debridement of chronic wounds (most typically leg ulcers), pressure ulcers, infected surgical wounds, dehisced wounds and diabetic ulcers [Fig 1].


WHEN TO USE LARVAL THERAPY Larval therapy is presently used to treat a variety of acute and chronic wounds in patients, both in hospital and community settings. In the UK as well as in the EU, US and Australia, larval therapy has been used to treat most types of infected, sloughy or necrotic wounds, irrespective of aetiology. Wounds that have been treated with larvae include leg ulcers, pressure ulcers, infected surgical wounds, dehisced wounds and diabetic ulcers as these wounds are usually covered with sloughy, necrotic tissue[16–22]


. Larval therapy has also been used as a


diagnostic tool to ascertain the extent of tissue damage in an ischaemic wound, and assess if a limb is worth saving[23]


. The speed at which


the larvae work can often expose the scope of a problem within a few days. In the case of a diabetic foot ulcer, the size of the wound on the surface may mask large quantities of devitalised tissue within the foot itself. Larvae will feed only as far as the dead tissue extends within the foot and will reveal how much healthy tissue is present[24,25]


. There are no known systemic medications


that interfere with or destroy the larvae whilst they are on the wound (see 'Practical Tips' box above for contraindications).


APPLICATION OPTIONS Larval therapy products are most commonly


available in two forms: n Free-range: where the larvae are applied directly to the wound and are not contained in any form of dressing


n Dressing form: where the larvae are contained within a netted pouch or bag. Use of free-range larvae is not subject to any


9. Robinson W, Norwood VH. The role of surgical larvae in the disinfection of osteomylitis and other infected wounds. J Bone Joint Surg 1933; 15: 409–412.


10. Fleischmann MD, Grassberger M, Sherman R. Maggot Therapy. Thieme, New York.


11. Rodgers, A. Maggots for the management of purpura fulminans in a paediatric patient. 2009;Wounds 5(4): 141–45.


12. Jones M, Thomas S. Larval therapy. Nurs Stand 2000; 14: 47–51.


13. Thomas S, Jones M, Wynn K, Fowler T. The current status of larval therapy in wound healing. Br J Nurs 2001; 10(22): S5–12.


14. Sherman RA. A new dressing design for use with maggot therapy. Plast Reconstr Surg 1997; 100: 451–56.


15. Chambers L, Woodrow S, Brown AP et al. Degradation of extracellular matrix components by defined proteinases from the greenbottle larva Lucilia sericata used for clinical debridement of non-healing wounds. Br J Dermatol 2003; 148(1): 14–23.


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