| OBJECTIVE: Liver and spleen hemorrhage is one of the most common diseases in abdominal trauma, and uncontrolled bleeding is the major cause of death. In this study high intensity focused ultrasound (HIFU) was used as a hemostatic technique to treat various kinds of liver and spleen injury in pig models. The purpose of this study was to investigate the safety, efficacy, and feasibility of HIFU in the treatment of the traumatic hepatic and splenic bleeding, to explore the mechanism of HIFU hemostasis, and to provide significant data for this novel acoustic hemostastic technology and its clinical application.METHODS: (1) Twenty-five healthy pigs were randomly divided into HIFU group (n=20) and control group (n=5). Three types of injury were made on livers as follows: 42 surgical incisions, 40 mm in length and 10-20 mm in depth; 18 perforating wounds, 15 mm in diameter and 10-20 mm in depth; 13 avulsed wounds, 60-100 mm in length and 25 mm in depth. The pigs in FflFU group received HIFU treatment for hemostasis, but the pigs in control group did not receive any intervention. (2) Two types of injury weremade on spleens in 10 pigs as follows: 20 surgical incisions, 40 mm in length and 10-20 mm in depth; 9 perforating wounds, 15 mm in diameter and 10-15mm in depth. (3) After the same injuries as part 1 were made on livers in 10 pigs, temporary block of hepatic blood flow was immediately performed, followed by HIFU hemostasis. (4) Twenty pigs were randomly divided into HIFU group (n=12) and control group (n=8). Using a machine that can produce controlled mechanical impacts on abdomen, the model of blunt liver trauma was established. HIFU treatment for hemostasis was performed in HIFU group, but in control group no intervention was performed. A HIFU hemostatic device with a frequency of 5.68 MHz was used in all treated animals. The therapeutic ultrasound was produced by a 50-mm diameter sphere transducer with focal length of 50 mm. The targettissue was exposed at acoustic focal peak intensities from 3,000 W cm (acoustic power 20W). During the treatment, effects of HIFU on liver and spleen hemorrhage, hemostatic time, and temperature at the treated tissue were recorded. After treatment, histopathologic examination was performed, and the functions of liver and kidney were measured.RESULTS: (1) HIFU can successfully stop the bleeding of various liver injuries. All pigs in HIFU groups survived, and no re-bleeding was detected after HIFU treatment. The animals in control group died of blood losing within 30-80 minutes after liver injuries. The mean hemostatic time for surgical incisions, penetrating wounds, and avulsed wounds was 27s, 71s,and 218s, respectively. The mean temperature was 82℃ in treated tissue immediately after bleeding stop. There was no change in functions of liver and kidney, except a transient elevation of serum AST one day after treatment. Pathological examination revealed that HIFU induced coagulative necrosis of hepatic tissue, including liver cells and blood vessel walls. Red thrombosis was observed in vascular cavity immediately after HIFU, and was gradually replaced by mixed thrombus. (2) HIFU can successfully stop the bleeding of various spleen injuries. The mean hemostatic time for surgical incisions, and penetrating wounds was 86s, and 95s, respectively. The mean temperature was 73℃ in treated tissue immediately after bleeding stop. Pathological changes were same as the changes in the liver. (3) While temporary block of hepatic blood flow was performed, the mean hemostatic time for surgical incisions, penetrating wounds and avulsed wounds in liver was 26s, 66s, and 133s, respectively. Compared with no intervention of blood supply, blocking flow reduced the treatment time for avulsed wounds. There was a significant difference between them. (4) HIFU can successfully stop the bleeding of blunt liver injuries. The mean hemostatic time was 6 minutes. All pigs in control groups died of blood losing within 30-60 minutes after liver injuries, while the animals survived af...
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