Medical Aspects of Chemical Warfare (2008) - The Black Vault

Medical Aspects of Chemical Warfarewound debridement have included powered dermabrasion,sharp surgical excision, laser debridement,and enzymatic debridement. 172–180 Powered dermabrasionhas been shown to speed up the reepithelializationprocess of cutaneous HD injuries. Kjellstrom et alfound sharp surgical excision with primary suturing ofthe skin defect to be effective in decreasing healing timeof HD vapor lesions in guinea pigs. 174, 175,177 Powereddermabrasion, pulsed CO 2laser ablation and erbium:yttrium-aluminium-garnet (Er:YAG) laser ablationhave been shown to accelerate the rate of healing offull-thickness cutaneous lewisite vapor burns in swinewithout the need for split-thickness skin grafting. 176,178Eldad et al found that excimer laser ablation and Debridase(Biotechnology General Ltd, Kiryat Malchi, Israel)enzymatic debridement were efficacious in improvingthe healing of partial-thickness nitrogen mustard burnsin a guinea pig model. 179Laser debridement of cutaneous vesicant woundshas proven to be an effective method of improvingthe rate of wound healing in pig models. Graham etal showed that viability, thickness, and organizationof the epidermis were all significantly improved bypartial-thickness pulsed CO 2laser debridement ofsmall, mild to moderately severe cutaneous HD vaporinjuries. 180 Laser debridement followed by skingrafting was as efficacious in improving the woundhealing of deep HD burns as sharp surgical tangentialexcision followed by grafting (the “gold standard”in human deep dermal/full-thickness thermal burnsmedicine). 172,173 Middermal debridement by sharp excisionor laser ablation without grafting produced lessdesirable results but was better than no treatment. 172,173A 4-fold improvement in reepithelialization of lewisiteinjuries was achieved at 1 week following laser dermabrasion,with almost 100% reepithelialization by 3weeks. 178 It is not apparent why these full-thicknesslewisite injuries (10 cm 2 ) did not require grafting, asdid HD injuries (12.6 cm 2 ) or as would a full-thicknessthermal burn. 172,173 There are differences in biochemicalaction and rates of spontaneous reepithelializationbetween lewisite and HD. 178 Further studies must beconducted to fully examine the comparative healingof deep lewisite, HD, and thermal injuries.Laser debridement offers additional benefits, includinghemostatic control during surgery, minimalrisk of exposure to aerosolized pathogens, and time efficiency.Another major advantage to the use of lasers isthe ability to control the amount of normal perilesionalskin that is removed. Eldad et al noted that controllingthe amount of tissue removed by surgical tangentialexcision is technically difficult, and laser ablation ofnitrogen mustard burns in a guinea pig model enabledcontrol of the amount of tissue removed with minimalblood loss. 179 Minimizing the amount of tissue removedis a cosmetic benefit to the patient.A number of lasers manufactured in the UnitedStates, Canada, and Europe may be considered forroutine debridement of vesicant injuries. Acland andBarlow have reviewed the current uses of lasers indermatological practice and list the types of lasersused for specific procedures. 181 They list CO 2and Er:YAG lasers as the most appropriate for cutaneousresurfacing. Er:YAG lasers have been used for a widevariety of procedures, ranging from facial resurfacingto burn debridement. 181–185 They have been shown tobe particularly useful in the debridement of partialthicknessburns and the management of deep lewisiteinjuries. 179,186 Unlike the Gaussian beam profiles createdby CO 2lasers, Er:YAG laser beams tend to be uniformand produce uniform depths of ablation. 185 (These techniquesrequire trained and skilled personnel taking allnecessary precautions including eye protection.)Another alternative under consideration for debridementof HD injuries is enzymatic debridement.The enzymes, categorized as proteolytics, fibrinolytics,and collagenases, are designed to dissolve necrotictissue from wounds, and they are often used to debridechronic wounds (eg, decubitus ulcers, venousstasis ulcers, arterial insufficiency ulcers, diabeticfoot ulcers). 186 Many have been found to be safe andeffective in removing devitalized tissue and acceleratinghealing in burns. 187–194 Any burn eschar present istypically surgically cross-hatched to allow the agentto penetrate into the wound. Other agents, such asthe bacterial proteolytic enzymes streptokinase andstreptodornase, have given disappointing results indeep burns because they do not break down the collagenthat separates vital from nonvital tissue. 195 Use offibrinolytics may impair wound healing of HD lesions,because fibrin is an early matrix protein essential forwound healing. Fibrinolysin is typically combinedwith deoxyribonuclease, and this combination alsodigests DNA in the dividing fibroblasts that play a rolein healing. 186 Some effective enzymes have producedbetter results than others, with enzyme concentration,skin moisture level, and the presence of certain antibacterialagents affecting results. Secondary dressingsare needed to keep the wound moist and to allow theseagents to work. 186 Klasen offers an excellent review ofthe use of enzymatic debridement agents in burns. 195The most popular and effective agents on the markettoday are collagenases and papain/urea combinations.A promising proteolytic enzyme extracted from thestem of the pineapple plant is in US and Europeanclinical trials for the treatment of deep partial- andfull-thickness burns. Enzymatic debridement of HDinjuries is a promising and cheaper alternative to laser284