Morphologic changes in soft tissues after ischmic insult, like those following trauma and injuries of thermic, pharmicologic or bacteriotoxic causation, have been studied as to their nature by a number of authors. Recent experimental evidence has been that two major factors determine the final outcome of a temporary ischemic insult; the resistance of parenchymal cell to ischenia and the abliity of blood vessel to maintain blood flow when the cause of ischemia is removed.
Generally, the duration of ischemia is prolonged, recovery is less likely in spite of restoration of circulation. Two hours has been generally accepted as the maximum time that a tourniquet may be left on extremity with safety during surgical procedure and ischemia for than 4 hours produce neuromucular functional impairment and delayed return of the temperature of skin and muscle of extremity.
We examine the histopathologic change of all soft tissue on limb of rat under ischemic condition of different duration and this study covers the morphologd change of immediate postichemic phase of different duration anp also phase of three days after restoration of circulation.
The purpose of this investigation is to study the overall effects of ischemia on the skin, subcutaneous tissues, muscle, tendon, nerve and than to focus on the histopathologic changes following ischemia, and also determine the critical time of ischemia on individual tissue, the time when the each tissue undergoes irreversible change during ischemic condition.
The results are as follows:
1. The least tolerable tissue to ischemic insult is muscle, and the most tolerable tissue is nerve.
2. The ischemic time when the individual tissue undergoes reversible change are 4 hours in muscle, 6 hours in skin and subcutaneous tissue, 8 hours in tendon, 8 to 12 hours in nerve.
3. The ischemic time when the each tissue shows irreversible change are 6 hours in muscle, 8 hours in skin and subcutaneous tissue, 8 to 12 hours in tendon, 8 to 12 hours in nerve.
4. Safe tourniquet ischemic time is maximum 4 hours, when the muscle degenerates.
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