Mechanism Of Avulsion Injury Tissue Necrosis In Pig Hind Leg And Its Prevention And Treatment

Skin avulsion injury is one of the common traumas. There is not ideal method in the treatment. It is very important to study the mechanism of avulsed tissue necrosis and search ideal circulation and viability prediction technique for keeping viable tissue maximaly while reducing the secondary necrosis minimally.In this study, We mimiced traffic accident, and have developed a machine with which we have created an avulsion injury pattern in hind leg of pig. The velocity of the mechine is 23.68km/h, intensity of pressure is 2.8kg/cn~2 . A 4×10cm random avulsed flap was created in the avulsed area for keeping ischemia Level of the avulsed tissue equally.Samples were took from the avulsed tissue immediately, 12, 24, 48, 72, hours and 7 days posttrauma, and were observed under light and electron microscope. It was found that the epidermides were partially or totally scaled in some avulsion areas, callagenous fibers of dermis were dissolved. Congestion and hemorrhage could be found in the dermis and subcutaneous. Endothelial cells were damaged in some vessels. The injury of proximal part of the avulsed skin flaps gradually renovated, while the distal part degenerated and became necrobiosis after injury. Focal necrosis happened in distal part 24 hours posttrauma. Junction Zone of survival and necrosis, which was caracterized by many inflammatory cells infiltration and thrombosis, could be found 48 hours after injury in the avulsed skin flaps. As compared with normal skin flap, avulsed skin flap's congestion, edema, inflammatory cells infiltration, degeneration and necrosis happaned early, seriously and developed quickly.The malanyldialehyde ( MDA) in serum and avulsed tissue was measured 1, 2, 4, 8, 12, 24 hours after trauma. The results showed the MDA increased constantly after trauma. It means that the free radicals may play a very important role in the necrosis of avulsed tissue. The amount of calcium in avulsed tissue also increased greatly. This results suggested that there was calcium over-load happened in avulsed tissue.We adopted thermometer, laser Doppler blood flowmeter and fluorescein to predict the viability of avulsed skin flap. The results showed that when surface temperature of the avulsed skin flap descended 2. 4℃, Doppler index was lower...