Laparoscopic Simulator

JJ Pierce, Kara Boatwright, Trevor Cowan, Lance Jones, Seth Munger, Zach Romney, Terri Bateman, Brady Woolford. Brigham Young University.

The need exists for a fixture that can simulate real intra-abdominal conditions during the early stages of benchmarking, developing, and testing of new innovative products and procedures for laparoscopy. Therefore, a senior engineering team at Brigham Young University is developing a laparoscopic simulator which replicates the conditions found within the human abdomen during laparoscopy. The simulator allows for insufflation of a cavity, heating, and tissue placement for manipulation. The simulator comprises an elastic membrane clamped between a frame and a plate. CO2 gas is insufflated through a trocar inserted through the elastic membrane. Trocar placement in the membrane may mimic typical placement during surgery. CO2 gas collects in a cavity between the elastic membrane and the plate to create a working space. The elastic membrane expands through the frame into a desired volume. The simulator is designed such that it can be used to simulate abdominal conditions for bariatric, normal, and pediatric patients. A recess is located on the plate where various tissues can be placed for cauterization, resection, or manipulation. Heating elements assist in replicating the temperatures encountered within the human abdomen. Instrumentation measures the temperature, humidity, and pressure conditions found within the cavity. Customized software is used to record and analyze the data that is measured. Extensive research has been conducted towards selecting an ideal elastic membrane for the abdominal simulator which will replicate the expansion of the abdomen experienced during laparoscopic surgery. The elastic properties of the membrane are critical to the performance of the laparoscopic simulator because it governs how the membrane expands when insufflated. Preliminary research discovered an average pressure versus deflection curve for an insufflated human abdomen which the simulator has been designed to replicate.  An initial simulator prototype was created to assess the pressure versus deflection curves of different elastic membranes. The abdominal deflection as a function of intra-abdominal pressure for the human studies compares very favorable to the results achieved from  the initial laparoscopoic simulator.

However, at pressures greater than approximately 5 mmHg the human abdomen no longer expands rapidly but instead pressurizes, due to reaching an elastic limit. Therefore, the abdominal deflection as a function of intra-abdominal pressure for the elastic membranes becomes increasingly disparate from that of the human studies at pressures higher than 5 mmHg. Additional testing of other elastic membranes at higher pressures is being performed to improve the comparison between the elastic membrane and the human abdomen. The results of these tests will be presented. A fixture that can simulate intra-abdominal conditions has been developed. Additional research is being conducted to optimize the environment within the simulator. The laparoscopic simulator provides the means for accelerated innovation by offering a unique, convenient test fixture that replicates laparoscopic conditions. 

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