R. L. McCauley

Bactericidal and wound-healing properties of sodium hypochlorite solutions : the 1991 Lindberg award

Toxic effects of sodium hypochlorite on wound healing elements have been confined to a restricted range of sodium hypochlorite concentrations. We investigated concentrations of sodium hypochlorite for antibacterial activity and tissue toxicity at varying time intervals. We attempted to find the efficacious therapeutic concentration that was both microbicidal and nontoxic. Gram-negative and gram-positive isolates (0.1/ml of 1 x 10(8)/ml) were introduced into various concentrations of buffered and unbuffered sodium hypochlorite solutions for determinations of bactericidal activity at 5-, 10-, 15-, and 30-minute intervals. Concentrations of sodium hypochlorite were 0.25%, 0.025%, and 0.0125%. In vitro assays with fibroblasts at the same concentrations were also performed to determine toxicity at the same time intervals. An in vivo incisional model was also used to determine the effects of sodium hypochlorite therapy on wound healing. Bactericidal effects were observed for concentrations as low as 0.025%. Tissue toxicity, both in vitro and in vivo, was observed at concentrations of 0.25% but not at a concentration of 0.025%. Although concentrations below this level were nontoxic, they were not bactericidal. Therefore a modified Dakins solution at a concentration of 0.025% is therapeutically efficacious as a fluid dressing, since it preserves bactericidal properties and eliminates the detrimental potential on wound healing.

Lack of long-term durability of cultured keratinocyte burn-wound coverage: a case report.

Cultured epithelial autografts have been advocated for permanent closure of skin surfaces after massive thermal injuries. A 10-year-old boy sustained a nearly 100% total body surface area burn (98% full-thickness) in an explosion accident. Cultured epithelial autograft was used to cover 70% of the total body surface area on postburn day 26. In spite of early success of coverage, 60% of cultured epithelial autograft areas blistered and sloughed over the ensuing weeks. Electron microscopic examination of a biopsy specimen of the healed cultured epithelial autograft (80 days after placement) revealed a lack of dermal attachments of the anchoring fibrils. Additionally, blister fluid that was taken from the bullae of the cultured epithelial autograft revealed levels of 18 ng/ml thromboxane and 24 ng/ml prostaglandin E2. These levels are significantly higher than those seen in acute burn blister fluid and indicate an ongoing inflammatory process. Cultured keratinocytes, although they provide early wound closure, may not provide adequate long-term coverage for patients with massive burns.

In vitro toxicity of topical antimicrobial agents to human fibroblasts

Topical antimicrobial agents are essential to optimal burn care. However, exposure of WI-38 human diploid fibroblasts (ATCC CCL 75) and fresh donor human dermal fibroblasts to silver sulfadiazine and mafenide acetate results in a significant reduction in cell proliferation, as determined by hemocytometer cell counts and total matrix protein assays, within 48 hr of exposure. Changes in cellular morphology and progressive deterioration of cytoplasmic organelles and the nucleus are seen with phase-contrast microscopy and transmission electron microscopy. These findings may explain the clinical observation of delayed wound healing after the use of topical antimicrobial agents.

Differential inhibition of human basal keratinocyte growth to silver sulfadiazine and mafenide acetate

The impact of topical antimicrobial agents on improving the survival of patients with major thermal injuries is significant. However, the effects of these agents on cells responsible for wound healing has only recently received attention. Fresh human basal keratinocytes were grown in serum-free modified MCDB 153 medium under standard tissue culture conditions. Cells were subsequently exposed to concentrations of silver sulfadiazine and mafenide acetate as low as 1/100 of that used clinically over a period of 5-7 days. Cellular responses documented with hemocytometer cells counts, cellular protein assays, phase-contrast microscopy, and transmission electron microscopy show only severe toxicity to mafenide acetate. Such data imply that inhibition of wound epithelialization is greater with the use of mafenide acetate than with the use of silver sulfadiazine.

Dural reconstruction of a class IV calvarial burn with decellularized human dermis

Calvarial burns involving the brain (Class IV) are reported to be rare. They represent a treatment challenge. Wound coverage can be accomplished with serial debridement of bone and grafting over granulating tissue, local flaps and free tissue transfer. The former techniques are often not feasible in the young infant. We present a successful case of a six-week-old female patient affected of full thickness burns involving the skull and brain. The bone, dura mater and superficial brain were debrided and the defect covered with AlloDerm and split thickness grafts. The area engrafted completely and no complications or CSF leak occurred. An acellular human allogeneic dermis (AlloDerm) can be successfully used to replace dura mater in burn patients.

The scalp as a donor site: Revisited

The scalp cannot be used as skin graft donor site with impunity. A review of 2,620 charts identified 194 pediatric patients whose scalps served as donor sites for split-thickness skin grafts for the treatment of acute burns. The overall incidence of alopecia was 32%. However, the incidence of alopecia in unburned scalps was 13%. The occurrence of alopecia in this group was associated with larger burn area requiring more frequent use of the scalp and shorter intervals between graft harvests (p less than 0.05). Among this group of patients (n = 15), nine had mild spotty alopecia, four had surgically correctable alopecia, and two had global patchy alopecia not amenable to surgical correction. In the patients with concomitant burns to their scalps, the incidence of alopecia was 61%. Whether the burn or the graft harvest caused alopecia could not be established. Meticulous donor site care is mandatory in this latter group when the scalp donor site is indicated.

In vitro alterations in human fibroblast behavior secondary to silicone polymers

The etiology of fibrous capsular contractures in patients with silicone prostheses is unclear. However, cellular responses to the silicone polymers of the prostheses have not been examined. The exposure of human dermal fibroblasts to the components of the silicone gel prosthesis results in a significant change in cellular configuration and a progressive reduction in cell proliferation as determined by total matrix protein assays and hemocytometer cell counts. Transmission electron microscopy, however, documents a twofold increase in the rough endoplasmic reticulum when cells are exposed to the silicone gel. These findings suggest significant alterations in the behavior of human fibroblast subpopulations in response to silicone polymers.

Management of Pediatric Perineal and Genital Burns: Twenty-Year Review

Between 1966 and 1986, fifty-seven pediatric patients with partial and/or full-thickness perineal and genital burns with a minimum of 1-year follow-up were identified. Fifty percent of the patients with genital burns and 20% of the patients with perineal and/or buttock burns required skin grafting in the acute stage. No patient required suprapubic cystostomies, diverting colostomies, or local flap coverage of exposed testicles. Burn scar contractures were the most frequent complications. Thirty-two patients (56%) required contracture release of the perineum and coverage with either skin grafts or local skin flaps. In three patients (6%) contracture required release of the penis and scrotum. One patient lost a testicle. Three patients developed rectal prolapse and were treated without surgery. Four patients developed rectal stenosis with fecal incontinence because of burn scar contracture and were treated by anal dilatation, local transposition flaps, and/or excision of the scar and primary closure. Acute management of pediatric patients with such injuries can be conservative. Delayed complications of contractures of the perineum and genitals can be easily corrected with scar excisions, skin grafts, or the use of local skin flaps.

Cadaveric allograft discards as a result of positive skin cultures

INTRODUCTIONnThe availability of cadaveric allograft is often limited by potentially pathogenic microbial organisms. Little data exists on cadaveric allograft discard rates related to positive microbiology. The purpose of this retrospective review was to determine the cadaveric allograft discard rates related positive microbiology and the subsequent breakdown of those organisms involved.nnnMETHODSnFrom January 1995 to June 1997, 1112 donors were screened and procured after informed consent had been obtained. The procedures used were in accordance with American Association of Tissue Banks (AATB) standards and guidelines. The number of discards due to positive skin cultures was reviewed and analyzed for type of microbial organism.nnnRESULTSnFifty-four donors (4.9%) were discarded due to positive skin cultures. Methicillin resistant Staphylococcus epidermidis, (MRSE), was the most predominant organism (22.2%), followed by gram negative rods as a group (18.5%), with Aspergillus species being the least predominant isolate.nnnCONCLUSIONnDespite the strict adherence to AATB protocol, microbial contamination of cadaveric allograft skin does not reach zero. It is not surprising that S. epidermidis was the predominant isolate, since skin is one of its common habitats. Continued vigilance in microbial testing remains paramount to ensure the quality of the allograft.

Use of previously burned skin as random cutaneous local flaps in pediatric burn reconstruction

Reconstruction after post-burn scarring remains a challenge. It is especially true in the severely burned patient, who normally presents with a paucity of donor sites. Healed skin from areas that had been burned and skin from grafted areas (termed as previously burned skin) have been occasionally used as flaps, but their safety is still in debate. We studied all patients undergoing burn reconstruction with normal skin flaps and previously burned skin flaps in the same operative procedure between April 1998 and October 1998 to determine the safety of flaps including burned and healed tissues. Patients served as their own controls. Three hundred and fifty-three local flaps were studied in 74 patients. These included 238 previously burned skin flaps and 115 normal skin flaps. There were no differences in complication rates between groups and only one previously burned skin flap suffered from complete necrosis. The use of local previously burned skin as flaps in burn reconstruction is safe. Reconstruction with flaps should be considered as first choice in burn reconstruction regardless of the quality of the local tissue.