STUDY ON CHARACTERISTICS OF BLAST-FRAGMENT COMBINED INJURY IN DOGS

It is known that blast wave and fragments are the primary causes of ca sualties from explosive weapons, To study the characteristics of blast -fragment combined injuries, functional and morphological changes were investigated in three groups of anesthetized dogs with blast injury, high velocity fragment extremity injury, and combined injuries of both types, The same parameters were also examined in a control group, Sev eral of the functions investigated were systemic pressure, mean pulmon ary arterial pressure (PAP), oxygenic partial pressure of arterial blo od (Po-2), thromboxane B-2(TXB(2)), and 6-keto-prostaglandin F-1 alpha (6-keto-PGF alpha). The morphologic study included gross, light micro scopic, and transmission electronic microscopic observations, In the b last injury group, Po-2 decreased and PAP, levels of blood plasma 6-ke to-PGF alpha and level of TXB(2) increased after injury, whereas PAP a nd level of 6-keto-PGF alpha decreased 24 hours after injury, The leve ls of 6-keto-PGF alpha and TXB(2), in lung tissues, lung/body weight i ndex were higher than those of the control group 24 hours after injury , The TXB(2)/6-keto-PGF alpha level in blood plasma increased slightly after injury, but showed no difference in lung tissue 24 hours after injury compared with the control group, The morphological changes show ed that most of the animals sustained moderate lung injury, In the fra gment injury group, Po-2 decreased slightly and PAP increased slightly after injury; the levels of 6-keto-PGF alpha, TXB(2) and TXB(2)/6-ket o-PGF alpha in blood plasma increased after injury and were higher in lung tissue than in the control group 24 hours after injury, The lung/ body weight index was nearly equal to that of control group, The morph ological changes showed that only a few animals suffered from mild lun g injury, In the combined injury group, Po-2 and PAP changed in a mann er similar to those of the other two injury groups but were more signi ficantly, The level of blood plasma 6-keto-PGF alpha decreased gradual ly, whereas that of TXB(2) increased permanently; thus, the levels of TXB(2)/6-keto-PGF alpha obviously increased after injury and were much higher than those in the other injury groups, The level of TXB(2) in lung tissue was higher than that of the control group 24 hours after i njury, but that of 6-keto-PGF alpha showed no change compared with tha t of the control group, and the level of TXB(2)/6-keto-PGF alpha was h igher than in the other three groups, The morphological changes showed that most of animals sustained severe lung injury, It is concluded th at extremity injury from high velocity fragment will aggravate lung bl ast injury, Changes in the levels of PGI(2) and TXA(2) can be used to determine the extent of injury in the three kinds of wounds, This may be useful for early diagnoses and rational treatment of the victims of explosion.