Real-Time Monitoring of Cerebrovascular Insufficiency due to Emergent Large Vessel Occlusion Using Near-Infrared Spectroscopy Based on the Modified Beer-Lambert Law: A Retrospective Study.

Abstract

Near-infrared spectroscopy (NIRS) is commonly used to assess brain tissue oxygen levels during surgery, but its applicability in the acute phase of stroke remains uncertain. We examined the usefulness of NIRS for rapid identification of acute large vessel occlusion (LVO) on hospital arrival. This pilot, single-center, retrospective study used a prospective database including all patients with suspected stroke. We performed NIRS upon hospital arrival. Based on the modified Beer-Lambert law, which enables high-frequency signal analysis, we used a newly defined index, pulse-oxygenation (PlsO₂), representing hemoglobin oxygen saturation derived from the pulsatile component of the NIRS signal. The primary outcome was the diagnostic accuracy of NIRS in distinguishing LVO from other conditions, assessed using the PlsO₂ ratios between the affected and unaffected sides. Data from 114 (40.4%) patients were analyzed. Relative PlsO₂ was lower in the LVO (n = 35) than in the non-LVO group (n = 79; 0.975 [0.874-0.991] vs. 1.022 [0.986-1.055], P < 0.001). The area under the receiver operating characteristic curve for relative PlsO₂ in LVO was 0.778 with sensitivity, specificity, positive predictive value, and negative predictive value of 74.3%, 69.6%, and 52.0%, and 85.9%, respectively, using an optimal cutoff. NIRS shows potential utility in detecting LVO in patients with suspected stroke. The results of this study provide a critical foundation for the future application of NIRS in the early identification and prehospital triage of LVO. Further large-scale studies are indispensable to establish its utility for early triage of emergency prehospital LVO.