Establishment of a high-velocity fragment-induced penetrating liver injury model in landrace pigs / 中华危重病急救医学

ABSTRACT

Objective:To establish a stable fragment-induced penetrating liver injury model in landrace pigs and evaluate the characteristics of deep tissue injury.Methods:According to the different positioning methods of aiming points, twelve healthy adult landrace pigs were divided into group A (the relative height "h" of the aiming point and the highest point of the body surface on the tracing line was set to 5 cm) and group B ("h" was set to 6 cm). Ultrasonography was used to determine the direction of fragment projection, and an experimental ballistic gun was used to project high-velocity fragments to cause injury to animals. The vital signs of the two groups were monitored, and whole blood cell count, blood gas analysis, and liver and renal function were tested. Damages to the liver and adjacent organs, as well as the amount of bleeding and survival time were analyzed.Results:For the overall analysis of the two groups, the liver hit rate of fragment simulating projectiles was 100% (right anterior lobe and right lateral lobe injury), the hit rate of other organs in the abdominal cavity was 25% (3/12), and the incidence of hemothorax or pneumothorax was 8% (1/12). The wounds were mainly characterized by liver lacerations, with total or partial disconnection of the distal liver lobe. There was no significant difference in wound length and bleeding amount between groups A and B [wound length (cm) 9.8±1.7 vs. 11.2±3.8, bleeding amount (g) 597.0±477.1 vs. 1 032.0±390.3, both P > 0.05]. The depth of liver parenchymal laceration in group B with the aiming point closer to the anterior median line was significantly longer than that in group A (cm 2.8±0.4 vs. 1.9±0.6, P = 0.015). Mean arterial pressure (MAP), pH value, residual arterial blood base (BE), hemoglobin (Hb) and hematocrit (HCT) levels decreased after the fragment-induced injury, and then reached a trough level [MAP (mmHg, 1 mmHg ≈ 0.133 kPa) 87.0±33.6, pH 7.26±0.15, BE (mmol/L) -6.65±8.48, Hb (g/L) 9.86±1.10, HCT 0.309±0.029, all P < 0.05] in the first hour. Blood lactate (Lac), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) levels increased over time, and reached a peak level [Lac (mmol/L) 10.21±4.40, LDH (U/L) 1 417.0±223.3, AST (U/L) 234.5 (162.5, 357.5), both P < 0.05] at 1 hour after injury. Pearson's correlation analysis showed that the total amount of bleeding was correlated with the depth of liver parenchyma laceration ( r = 0.684, P = 0.014). The Kaplan-Meier survival curve showed that the 3 hours survival rate in group A was higher than that in group B, but the difference was not statistically significant [83.3% (5/6) vs. 33.3% (2/6), P > 0.05]. Conclusions:The high-velocity fragment-induced penetrating liver injury model established by striking landrace pigs closer to the anterior median line with fragment simulating projectiles is reproducible and the degree of damage is controllable, and the model is applicable to further relevant research of hepatic ballistic trauma.