Abstract Body (Do not enter title and authors here): Background: Early detection and intervention of stroke have been shown to significantly reduce the burden of stroke-related disability and healthcare costs. The challenge, however, is that early detection is limited by currently available monitoring technologies. Non-invasive optical brain pulse monitoring (OBPM) offers bilateral, continuous measurement of brain pulse waveforms, from which cerebral oxygen saturation (StO₂%), intracranial pressure (ICP), and brain compliance can be derived. The use of OBPM in high-risk cardiac surgery may enable real-time identification of cerebral events and allow for early intervention.

Aims: To observe and characterise the OBPM signal changes in cardiac surgery patients during the perioperative period.

Methods: Eight patients aged between 59 and 85 underwent coronary artery bypass graft procedures with OBPM measurements taken pre-, intra-, and post-operatively for up to 12 hours. Three patients had simultaneous procedures: one mitral valve repair and one left atrial appendage ligation.

Results: Cardiopulmonary bypass time ranged from 68 to 151 minutes, with 53 to 120 minutes of cross-clamp time. Seven patients underwent continuous flow bypass, and one underwent pulsatile flow bypass. No OBPM device-related adverse events were reported during the study. The OBPM showed distinct waveforms pre-, intra-, and post-operatively, with unique signals during pulsatile and continuous bypass. One patient experienced two intraoperative cardiac arrests, with the OBPM demonstrating signatures of significant cerebral hypoxia during both episodes. Three patients showed reduced brain compliance intraoperatively, which normalized before sternal closure. Six episodes across two patients of transient reduction in cerebral oxygen saturation (<10%) were identified.


Conclusion: OBPM successfully identified distinct waveform patterns and provided indications of cerebral hypoxia during cardiac arrest, and changes in brain compliance in patients undergoing high-risk cardiac surgery with no device-related adverse events.
Continuous, non-invasive optical brain pulse monitoring is a safe and effective tool in the perioperative management of high-risk cardiac surgery patients. The benefits of early detection and informed clinical decision-making will significantly impact both clinical and economic value for healthcare stakeholders.