SAVING THE ZONE OF STASIS IN BURNS WITH RECOMBINANT TISSUE-TYPE PLASMINOGEN-ACTIVATOR (R-TPA) - AN EXPERIMENTAL-STUDY IN RATS

Hypercoagulability 2-3 h following scald injury and vessel thrombosis are well-known complications of burn injury. The present study was des igned to determine the effect of recombinant tissue-type plasminogen a ctivator (r-tPA) on vessels thrombosis in zones of stasis postburn, Tw enty rats were assigned to experimental and control groups (N:10). Aft er shaving the backs, a 'comb burn' was given bilaterally on the back of the rats 0.5 cm lateral and parallel to the midline by using a bras s probe consisting of four rows (10 x 20 mm) and three interspaces (5 x 20 mm), Standardized full-thickness burns of the experimental group were treated with r-tPA via femoral veins 2 h after the burn, while th e control group rats were infused the same volume of saline. Interspac es between the rows and vertical space area were evaluated as zone of stasis. The skin blood flow measurements of interspaces revealed a dec reased level immediately and 2 h after the burn injury, averaging 11.3 and 9.8 perfusion units, respectively. On day 7, blood flow measureme nts of interspace and vertical space areas significantly differed betw een the groups, averaging 11.9 PU in the experimental and 1.8 PU in th e control groups (P<0.05), To evaluate perfusion, each rat received 3 mCi of technetium-99m methoxyisobutylisonitrile on the first or sevent h day postburn. After 30 min, the entire back skins including the pann iculus carnosus muscle layer were dissected away. Gamma camera images revealed that in the experimental group the interspace areas took up 6 0-90 per cent more radioactivity than the burned areas while in the co ntrol group 20-50 per cent more activity was taken up by the interspac e area when compared to burned areas. Autoradiography gave the exact b orders of the necrotic and survived tissues. The percentage of live in terspace and vertical space areas in the experimental group was 87.8 p er cent on day 7, while it was 31.8 per cent in the control group (P<0 .05). Dry/wet ratios did not reveal any significant difference at 24 h postburn. These results confirm that treatment with this selective fi brinolytic agent (r-tPA) after burn injury would have some benefits on saving the zone of stasis in burns. (C) 1998 Elsevier Science Ltd for ISBI. All rights reserved.