Abstract Body: Introduction:
Stroke is a leading cause of global mortality and morbidity, affecting approximately 15 million people annually, with ischemic stroke accounting for 85% of cases. Endovascular clot retrieval (ECR) has become a key treatment for large vessel occlusion (LVO) strokes. While ECR significantly improves outcomes, it carries risks, including emboli to new territories. This cohort study evaluates the feasibility of Optical Brain Pulse Monitoring (OBPM) for detecting stroke-related events during ECR, aiming to enhance patient safety by providing real-time feedback on cerebral blood flow changes.

Methods:
Sensors from a non-invasive OBPM (Cyban, Australia) were placed bilaterally over the middle cerebral artery (MCA) territories in 11 LVO stroke patients undergoing ECR. The OBPM uses both red and infrared light to detect brain pulse waves associated with blood volume and oxygen changes with each cardiac pulse. A qualitative assessment of unique brain pulse waveforms associated with stroke was completed.

Results:
Abnormal brain pulse waveforms were observed in all 11 strokes. Changes were present over the ipsilateral and contralateral hemispheres. The brain pulse waveforms were similar to waveforms found in the central venous circulation. Abnormal waveforms were split into two categories based on the degree of venous features; 1) The Hybrid waveform which demonstrated a mix of arterial and venous features and 2) The Venous waveform in which venous features dominated (Figure 1). All patients displayed one or both of these abnormal waveform classes. Patients exhibiting the Venous waveform were more likely to have a larger stroke at presentation and worse outcomes, with more days in hospital (adjusted for death), compared to individuals displaying the Hybrid waveform (p<0.05).

Discussion
This study underscores the use of OBPM during ECR. The brain pulse waveforms may also offer pathophysiological insights suggesting the venous circulation has a dominate influence on the cerebral microcirculation in LVO strokes due to reduced arterial pressure levels. The presence of the Venous waveform may indicate a large region with very low arterial pressure and cerebral blood flow, as well as larger stroke and poor prognosis.

Conclusion:
OBPM shows promise during ECR by characterizing abnormal waveforms, providing insights into the pathophysiological mechanisms underlying stroke and brain injury, thus offering new avenues for early detection and prognostication in stroke.