Near-infrared spectroscopy monitoring during endovascular treatment for acute ischaemic stroke

Introduction: The aim of endovascular treatment (EVT) for acute ischaemic stroke is to relieve the cerebral tissue hypoxia in the area supplied by the occluded artery. Near-infrared spectroscopy (NIRS) monitoring is developed to assess regional cerebral tissue oxygen haemoglobin saturation (rSO(2)). We aimed to investigate whether NIRS can detect inter- and intra-hemispheric rSO(2) differences during EVT. Patients and methods: In this prospective, observational study, patients undergoing EVT for a proximal intracranial occlusion of the anterior circulation between May 2019 and November 2020, were included. A four-wavelength NIRS monitor (O3((R)) Regional Oximeter (Masimo, Irvine, CA)) was used to measure rSO(2) during EVT with sensors placed over the temporal lobes in 20 patients and over the frontal lobes in 13 patients. The Wilcoxon signed-rank test was used to test for inter-hemispheric rSO(2) differences after groin puncture and after recanalisation, and intra-hemispheric rSO(2) changes before and after recanalisation. Results: In the temporal cohort, no inter-hemispheric rSO(2) differences were observed after groin puncture (median [IQR] rSO(2) affected hemisphere, 70% [67-73] and unaffected hemisphere, 70% [66-72]; p = 0.79) and after recanalisation. There were no intra-hemispheric rSO(2) changes over time. In the frontal cohort, no inter- and intra-hemispheric rSO(2) differences or changes were found. Discussion and conclusion: A NIRS monitor could not detect inter- and intra-hemispheric rSO(2) differences or changes during EVT, irrespective of the sensor position. It is likely that even with temporal sensor application, a significant proportion of the received NIRS signal was influenced by oxygenation of surrounding tissues.