Application of Electrical Impedance Tomography for Continuous Monitoring of Retroperitoneal Bleeding After Blunt Trauma

Retroperitoneal bleeding is commonly associated with blunt trauma to the abdomen. Current medical tools cannot be used for continuous monitoring of the bleeding. In the study, electrical impedance tomography (EIT) was applied to monitoring the retroperitoneal bleeding of an animal model. Six healthy swine were used. The process of retroperitoneal bleeding was simulated by the continuous injection of anticoagulated blood. For each subject, total blood of 200 mL or more was injected within different time periods ranging from tens of minutes to two hours. The bleeding was detected and monitored continuously by EIT system with 16 electrodes at a rate of one image per second. EIT images were reconstructed by dynamic back-projection algorithm. Mean resistivity value (MRV) of the bleeding region in EIT images was calculated and plotted over time. We found that impedance changes caused by the bleeding could be revealed by EIT images and MRV curves. MRV curve varied approximately linearly with the quantity of blood injected using regression analysis (R2 = 0.90 to 0.99, p < 0.05). In total, 20 mL of blood volume changes could be identified by EIT. The progression of the retroperitoneal bleeding can be monitored by EIT in the proposed animal model. It suggests EIT is potential as a useful tool for continuous monitoring of retroperitoneal bleeding after blunt trauma.