In situ production of a synthetic barrier dressing for burn wounds in rats

We describe the in situ production of a burn wound dressing applied to eschar that completely isolates burned tissue from contamination with Pseudomonas aeruginosa. Anesthetized, adult rats were subjected to a scald burn over 10% of their body surfaces. One-half hour later a test dressing presumed to be a barrier to bacterial contamination of the wound was applied to the burned surface. Tannic acid, vaseline, ethyl linoleate, collodion, and polyhydroxethylmethacrylate (PHEMA) were evaluated. Each agent was applied directly to the burned surface. A solid film of the PHEMA was produced on the eschar by addition of solvent and a powdered form of the polymer. The surface of each synthetic dressing was contaminated 30 min after application by the addition of 10(8) P. aeruginosa. Also, a control set of rats was burned and their eschars were directly contaminated without application of the test dressing. Seven days later the contaminated muscle under the burned area in 10 control rats had P. aeruginosa counts of 10(7) to 10(8) per g of muscle (wet weight). Of the materials tested, only PHEMA consistently acted as an effective barrier dressing, reducing bacteria in the muscle to undetectable levels in 11 of 14 tests. It was also possible to treat contaminated eschar through this synthetic dressing by topical application of antibiotics to the barrier surface. The results suggest a novel clinical approach in which a barrier dressing could be used to isolate a burn eschar from environmental and subject contamination until the wound site is ready for grafting.