Heparinized swine models for better surgical/endoscopic training.

Introduction: Animal experiments with large living animals are essential for the development of medical devices and the training of surgical procedures. Swine are frequently used in animal experiments due to their similar size and anatomy compared to humans. However, it is well known that swine has less local bleeding than humans. The aim of the study was to verify whether animal models with appropriate local bleeding capability could be established. Methods: The activated clotting time (ACT) was measured for eight swine (piglet, 35 kg) under general anesthesia. The flexible endoscope was advanced orally, and the gastric mucosa was intentionally traumatized to bleed by biopsy forceps, and the time until spontaneous hemostasis was obtained (mucosal bleeding time). Then, heparin (50 U/kg) was administered intravenously. After 10 min, the ACT was remeasured, and the gastric mucosa was again damaged to bleed by biopsy forceps. The mucosal bleeding time was remeasured. The above measurements were repeated until the ACT exceeded 200 s. Results: The median ACT values (seconds) were 83 (no heparin), 155 (50 U/kg heparin), and 204 (100 U/kg heparin), which were significantly increased. The median mucosal bleeding times (seconds) were 152 (no heparin), 283 (50 U/kg), and 423 (100 U/kg), which were significantly extended. Conclusion: A bleeding animal model for surgical and endoscopic training was successfully established by bolus heparin administration.