Topical silver treatment after escharectomy of infected full thickness burn wounds in rats.

White male Sprague Dawley rats (200 g.) with 20% full thickness scald burns seeded with 10 Pseudomonas aeruginosa, strain 59-1244, were used as experimental animals. Studies including the following: (1). Control groups. (2). DC pretreatment groups. (3). Treatment groups. P. aeruginosa infected burn wounds were excised, and then treated with either autograft or silver-nylon dressings, with (SNDC) or without (SN) application direct current. Excision and treatment were initiated 1, 2, 3, 4 or 5 days after burning and inoculation. (4). Groups for antimicrobial barrier function study. Mortality of each group was recorded at 21 days PB. With burns alone, there was no mortality. Without treatment 19 of 20 burn inoculated controls died. In the pretreatment study, the mortality of the group pretreated with SN was 95% while that of the group pretreated with SNDC was only 30%. With excision and autografting, PB mortality rose from 5/20 at day 2 PB to 19/20 at day 3 PB. In the excision and SN groups, mortality rose from 5/20 at day 3 PB to 18/20 at day 4 PB. In the excision and SNDC groups, mortality rose from 5/20 at day 3 PB to 18/20 at day 4 PB. In the antimicrobial barrier function study, the 10% mortality in the SN dressing group was significantly less than that of 95% in the plain nylon dressed group. Histologic examination revealed progressively deepening colonization of non-viable wound tissue, progressing to invasion of underlying viable tissue by PB day 4. With wound excision, SN, SNDC, and autografting were equally protective for the first two days, but only SN and SNDC extended this effect to the third PB day. In conclusion, SN and SNDC have a strong local anti-microbial effect on the burn wound when applied within 72 hours of the time of bacterial inoculation, but little effect if applied after the bacteria have invaded unburned vessels and viable tissue adjacent to the burn.

Integra as a dermal replacement in a meshed composite skin graft in a rat model: a one-step operative procedure.

BACKGROUND: Current use of Integra, the collagen-based dermal analogue, requires a two-step grafting procedure to achieve wound closure with an "ultrathin" autograft. METHODS: A one-step operative procedure of meshed composite skin graft (MCSG) using Integra as a dermal template for a meshed split thickness autograft was developed in rats. The silicon layer of Integra was removed, the resulting dermal analogue was meshed (1:1.5), expanded, and placed on excised full thickness wound and covered with a meshed (1:1.5 or 1:6) split thickness autograft. Grafted wounds were dressed with BioBrane, Vaseline gauze, silver-impregnated nylon, or silver-nylon and direct current (SNDC). At scheduled intervals up to 3 months postgrafting, wounds were examined for epithelialization, collagen deposition and fibrosis, hair growth, and contraction. The results of wound closure and healing following the one-step procedure were compared with the outcome of the two-step grafting procedure where application of meshed Integra (step one) was followed in 14 days by removal of the silicon layer and application of the meshed autograft (step two). RESULTS: The one-step procedure applied to meshed autograft/Integra (1:1.5/1:1.5) composite graft accelerated wound closure by 6-19 days when compared with the two-step procedure. At 3 months postgrafting, the contraction of the healed wound dressed with SNDC, BioBrane, or Vaseline gauze was reduced by 13-16% following the one-step procedure compared with the two-step procedure (p < 0.05). The one-step procedure allowed the expansion of the autograft layer to 1:6 while achieving wound healing results similar to grafting with 1:1.5 meshed autograft layer using the two-step grafting procedure. CONCLUSION: Single-step application of meshed, thin, split thickness autograft over meshed Integra-derived dermal substitute allows more rapid wound closure with less contraction and more efficient use of graft donor skin than can be obtained with the commonly used two-step grafting procedure.