Optical brain pulse monitoring of microvascular blood flow during endovascular treatment for acute ischemic stroke

BackgroundEndovascular treatment (EVT) of large vessel occlusion (LVO) strokes improves patient outcomes. However, significant challenges remain including detection of microvascular no reflow phenomena, emboli to new territories and improving neuro-prognostication. Real time monitoring of the brain microcirculation could assist in addressing these challenges. This first-in-human cohort study evaluated Optical Brain Pulse Monitoring (OBPM) of microvascular blood flow during EVT. MethodsOBPM is a non-invasive device using red and infrared light to capture brain pulse waveforms, reflecting the relative arteriole and venous pressure levels driving microvascular blood flow. OBPM brain pulse classes - Arterial, Hybrid, Venous I, Venous II and Monotonous - represent a continuum of blood flow states from normal (Arterial) to critically low blood flow (Monotonous). OBPM sensors were positioned bilaterally over the middle cerebral artery territories of LVO stroke patients undergoing EVT. Data on patient demographics, imaging and clinical outcomes were collected. ResultsEleven patients (mean age 71, NIHSS 13) were enrolled. The most common brain pulse class at presentation was the Venous I (64%). The brain pulse class at presentation was associated with the hypoperfused tissue volume (p = 0.005). The brain pulse class following EVT was associated with long-term patient outcomes, including length of hospital stay (p = 0.04), the modified Rankin Score (p = 0.06) and hospital death (p = 0.02). In one patient, OBPM detected an embolization to a new territory that occurred during internal carotid artery stenting. ConclusionThe OBPM brain pulse waveforms demonstrated venous circulation features in patients presenting with LVO stroke. These waveforms were also associated with clinical outcomes, such as stroke size at presentation, hospital LOS and mortality. Monitoring of the brain pulse during EVT could improve intra-procedural evaluation of microvascular no reflow, detection of complications and neuro-prognostication. OBPM also has potential as a simple method for earlier LVO stroke detection. Clinical trial registrationURL:https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=384769&isReview=true; Unique identifier: ACTRN12622001320741