Emergency War Surgery NATO Handbook: Part III: General Considerations of Wound Management: Chapter XVI: Wounds and Injuries of the Soft Tissues
United States Department of Defense
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From the time a wound is inflicted until healing is complete, the surrounding area is in a state of constant change In the first few hours after an extremity is exposed to the violent temporary cavity stretch of the AK-74 wound, a marked vasoconstriction of these tissues is revealed by skin blanching for a distance of 6-8 cm from the skin edges. Marked hyperemia appears around the blanched area and gradually encroaches upon it, eventually replacing it entirely in about four hours. Although less dramatic than the skin changes, increasing perfusion of muscle surrounding the missile path has been clearly demonstrated for up to 72 hours after wounding.
Since blood flow in the muscle around the projectile path is changing, it is difficult -at best for the surgeon, at any point in time, using any set of guidelines, to be certain of excising only (but all of) the nonviable muscle, and not viable muscle. Writings in the past two decades have demanded this judgment of our young surgeons when even the most experienced combat surgeon was not always certain. This was demonstrated in the Vietnam conflict when some wounds, which were treated in accordance with the conventional "4 c" guidelines (color, contraction, consistency, circulation) were noted on arrival at another hospital, a few days later, to have obviously necrotic muscle Some surgeons at this higher echelon of care concluded that the initial debridement had been done improperly. The 5th CINCPAC War Surgery Conference in 1971 corrected that misconception by stating that the later appearance of necrotic tissue in a wound "does not necessarily mean that the original debridement was improperly done," but rather was the result of the transitory dynamics of wound physiology at the time of the original debridement.
From a practical standpoint, the question is not whether or not to excise devitalized tissue, for there is good agreement here, but rather how to accurately differentiate muscle that is injured but will heal from that muscle which is nonviable and should be excised. Generations of surgeons have accepted the assumption that nonviable muscle can be identified by its dark color, its "mushy" consistency, its failure to contract when pinched with forceps, and the absence of brisk bleeding from a cut surface (the 4 c's). The surgeon inclined to err in the direction of radical excision should bear in mind that in all studies in which animals were kept alive long enough to observe and measure wound healing objectively or to evaluate the pathology around the missile wound microscopically, there was less lasting tissue damage than estimated from observation of the wound in the first few hours after the wound was inflicted. The foregoing notwithstanding, the surgeon must base judgment on decisions made at the table at the time of operation. The majority of combat surgeons continue to utilize the 4 c's as guidelines and consider it prudent to excise muscle of questionable viability.
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