Thesis Defence: Optimization of a Lower Body Negative Pressure Chamber to Control the Left Ventricular Pressure of Rodents

Nasim Hajati, supervised by Dr. Rudolf Seethaler, will defend their thesis titled “Optimization of a Lower Body Negative Pressure Chamber to Control the Left Ventricular Pressure of Rodents” in partial fulfillment of the requirements for the degree of Master of Applied Science in Electrical Engineering.

An abstract for Nasim Hajati’s thesis is included below.

Defences are open to all members of the campus community as well as the general public. Registration is not required for in person defences.

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ABSTRACT

Assessing the performance of cardiovascular system is a crucial part of testing new medications and biomedical devices. To ensure the safety of these new medictaions, it is important that their impact on performance factors, such as the strength of heart muscles or the elasticity of heart cells when filled with blood, be evaluated. These tests are typically performed on animals; specifically, rodents have been playing a significant role in such biomedical experimentations. Traditional methods of studying the cardiovascular system involve invasive surgeries to reach the heart and its vessels, to manually manipulate the blood return flow to the left ventricle and monitor the change in the patterns of ventricular or arterial pressure and volume through plotting pressure-volume graphs. These surgical methods often lead to blood loss or damage to vessels and organs of the rodents, which affects the test results, making them less accurate, and are subject to human error.

Considering the issues of the traditional approaches, one solution in the literature is to use a Lower Body Negative Pressure (LBNP) chamber, sealed around the lower body of the rodents, and create suction inside the chamber to control the blood flow to the heart by drawing the blood toward the lower body, as a result of the negative pressure. To remove the direct human intervention, an automated servo-controlled system was built by previous UBC students, which controlled the blood pressure level, to be later plotted against the measured volume. This study aims to optimize the previously built system, to increase the speed and safety of the device. In addition, this study performs system identification on the automated chamber and rodents’ left ventricular pressure models and designs an optimal robust controller for the system based on the derived models.