High-voltage electrical injury: chronic wound evolution.

A chronic electrical burn model employing documentary and diagnostic techniques was designed in the primate for investigating wound evolution up to 10 days after injury. A standardized 40-kJ, 3500-V, 4.2-A, 2.5-s bilateral, symmetrical upper extremity electrical injury was performed. Gross observation studies documented tissue injury extending more proximally on the deep surfaces of individual muscles and between muscle layers. Specific regions, or "choke" points, in the forearm exist in which decreased cross-sectional areas and highly resistant tissue composition resulted in increased heat production and more severe tissue damage. Muscle injury was analyzed using light microscopy, revealing patchy cellular necrosis intermixed with viable cells. Digital subtraction angiography demonstrated segmental narrowing and "pruning" of large vascular trunks with a significant decrease in nutrient vessels in affected areas. Ulnar nerve conduction studies showed loss of conduction proximal to the cubital fossa with no recovery. Although characteristic patterns of injury were documented in skin, muscle, vessels, and nerves, no experimental evidence was found for progressive necrosis.