Freezing and decay effects on material properties of porcine kidney and liver

Abdominal injuries caused by traffic accidents have severe consequences and are major causes of death in the United States. Several experiments were performed in the past on post-mortem human surrogate (PMHS) to quantify the abdominal tolerance under impact loading. However, some concerns were raised regarding the PMHS storage and its influence on the biomechanical response of internal organs. To better examine the freezing and decay effects, this study analyzed the data obtained from indentation performed on porcine abdominal organs. Porcine kidney and liver specimens were cut with a custom blade assembly from fresh organs. Indentation ramp-hold tests were first conducted on fresh specimens, which submerged in physiological saline at room temperature during testing. Specimens were then preserved using two different storage methods (cooling and freezing) and retested after 20 days at the room temperature. Quasi-linear viscoelastic model was utilized to model the indentation data, and statistical analysis was conducted to investigate the significance of the model parameters. Significant differences between freezing and cooling effects were found for liver, and the instantaneous responses were significantly changed for both kidney and liver. It is believed that the results of this study may help in development of appropriate preservation methodologies for abdominal organs and better understanding the published results of the abdominal tests performed under impact loading corresponding to vehicle accidents.