PID Controlled Epidural Electrical Stimulation for Managing Orthostatic Hypotension in Individuals with Spinal Cord...

Hemodynamic instabilities, such as orthostatic hypotension, are under-appreciated consequences of high-level spinal cord injuries (SCI), increasing cardiovascular disease risk and reducing quality of life. We previously demonstrated that epidural electrical stimulation (EES) has shown efficacy in managing hypotensive complications by eliciting pressor responses through targeted thoracic spinal cord stimulation in 14 individuals with SCI. This system enables users to select stimulation programs from a predefined library for daily activities. However, the burden of manual control and self-monitoring limits its usability.To address this, we leveraged the closed-loop capabilities of an implantable EES system to develop patient-optimized proportional-integral-derivative (PID) controllers in 8 individuals with SCI. In this paper, we detail how the system dynamically adjusts stimulation amplitudes in real-time based on continuous blood pressure monitoring. We designed a framework to interface with the EES system and evaluated its performance in extreme orthostatic challenges involving dynamic tilt-table tests. Compared to continuous stimulation, closed-loop modulation reduces systolic pressure variability, reduces battery consumption of the implanted device, and increases EES reactivity to rapid hemodynamic changes.These findings demonstrate the efficacy and safety of closed-loop EES for managing orthostatic hypotension and establish methods for continuous, autonomous blood pressure regulation in real-world conditions.Clinical Relevance-This establishes the potential for closed-loop strategies to manage hypotension in daily-life settings.