Endovascular Embolization Techniques in a Novel Swine Model of Fatal Uncontrolled Solid Organ Hemorrhage and Coagulopathy

Abstract

Endovascular embolization is increasingly used in treating traumatic hemorrhage and other applications. No endovascular-capable translational large animal models exist and coagulopathy's effect on embolization techniques is unknown. We developed a coagulation-adaptable solid organ hemorrhage model in swine for investigation of embolization techniques. Anesthetized swine (n=26, 45±3kg) had laparotomy and splenic externalization. Half underwent 50% isovolemic hemodilution with 6% hetastarch and cooling to 33-35°C (COAG group). All had controlled 20mL/kg hemorrhage and endovascular access to the proximal splenic artery with a 4F catheter via a right femoral sheath. Splenic transection and 5min free bleeding were followed by treatment (n=5/group) with 5mL gelfoam slurry, three 6-mm coils, or no treatment (n=3, control). Animals received 15mL/kg plasma resuscitation and were monitored for 6hr. Splenic blood loss was continuously measured and angiograms were performed at specified times. Coagulopathy was successfully established in COAG animals. Pre-treatment blood loss was greater in COAG (11±6mL/kg) than non-COAG (7±3mL/kg, P=0.04) animals. Splenic hemorrhage was universally fatal without treatment. Non-COAG coil survival was 4/5 (326±75min) and non-COAG Gelfoam 3/5 (311±67min) versus non-COAG Control 0/3 (82±18min, P<0.05 for both). Neither COAG Coil (0/5, 195±117min) nor COAG Gelfoam (0/5, 125±32min) treatment improved survival over COAG Control (0/3, 56±19min). Post-treatment blood loss was 4.6±3.4mL/kg in non-COAG Coil and 4.6±2.9mL/kg in non-COAG Gelfoam, both lower than non-COAG Control (18±1.3mL/kg, P=0.05). Neither COAG Coil (8.4±5.4mL/kg) nor COAG Gelfoam (15±11ml/kg) had significantly less blood loss than COAG Control (20±1.2mL/kg). Both non-COAG treatment groups had minimal blood loss during observation, while COAG groups had ongoing slow blood loss. In the COAG Gelfoam group, there was an increase in hemorrhage between 30 and 60min following treatment. A swine model of coagulation-adaptable fatal splenic hemorrhage suitable for endovascular treatment was developed. Coagulopathy had profound negative effects on coil and gelfoam efficacy in controlling bleeding, with implications for trauma and elective embolization procedures.