[Ultrastructural changes in pulmonary microvascular damage in rats inflicted with burn, blast and combined burn-blast injury].

The pathological changes in pulmonary microvasculature in rats inflicted with overpressure blast, 15% third degree burns and combined burn-blast injury, respectively, were studied with electron microscopy and ultrastructural morphometry. Results indicated that the pathological changes in pulmonary microvasculature in 15% third degree burns were slight, and mainly restricted to ultrastructural level. While in severe blast and burn-blast injuries, the damage of pulmonary microvasculature including endothelial swelling and regeneration and dispersal of arteriole wall structure, was prominent. These changes form the basis of pulmonary hemorrhage and edema. Apart from vessel structural damages, arteriole constriction and capillary closure were also observed during 2 to 4 h postinjury. The vessel damage and dysfunction were more severe in combined injury than in blast injury alone. The mechanisms needed to be studied further.