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UBC Theses and Dissertations

Development of a minimally invasive implantable optical sensor to monitor spinal cord oxygenation using near-infrared spectroscopy Askari, Shahbaz


Neurological damage after traumatic spinal cord injury (SCI) occurs in two stages: an acute phase (<48 hours) and a subacute phase (48 hours to 14 days), often causing severe hemorrhage. The primary treatment involves raising mean arterial pressure (MAP) to enhance blood flow and boost oxygenation levels of spinal cord tissue. A crucial challenge in managing acute SCI is the need for techniques that non-invasively measure real-time blood flow and oxygenation. Continuous-wave near-infrared spectroscopy (CW-NIRS) offers benefits such as portability, cost-effectiveness, and safety due to its employment of non-ionizing, near-infrared radiation. However, it has limitations such as moderate spatial resolution, restricted penetration depth, and low signal-to-noise ratio. To counter these challenges, researchers have proposed the use of an implantable NIRS sensor. However, most of the research surrounding this approach has, so far, been mainly conducted in animal models. Hence, the primary objective of my research was to transition this approach from animal models and adapt it for clinical applications in SCI. In my research, I progressed from the SC-NIRS V4 sensor (Spinal Cord NIRS version 4 sensor), designed to validate a fabrication technique for more complex and precise encapsulation fabrication. Next, by developing SC-NIRS V5, I incorporated an implantable silicone elastomer for sensor encapsulation and an implantable connector to simplify the sensor’s implantation and removal process. I also developed the SC-NIRS V6 platform, specifically designed to accommodate a spatially resolved (SR) NIRS algorithm for improved accuracy. My research program was successfully concluded by implanting a SC-NIRS V5 sensor, which I designed and developed in a patient with acute traumatic spinal cord injury for the first time. The sensor effectively monitored and recorded spinal cord tissue oxygenation for 42 hours with a high degree of accuracy, providing valuable data that matched the patient's clinical condition. This is the first reported continuous monitoring of spinal cord oxygenation in a human participant using an implantable sensor.  

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