Background: Near-infrared spectroscopy (NIRS) is an alternative monitoring method during carotid artery stenting (CAS). NIRS has been reported to be effective in emergency care; however, it is unknown whether it can predict intraoperative ischemic intolerance and cerebral hyperperfusion during CAS. Perioperative ischemic intolerance and cerebral hyperperfusion are potential events during CAS for carotid artery stenosis. We evaluated whether perioperative monitoring of the tissue oxygenation index (TOI) using NIRS with the NIRO system can predict the occurrence of ischemic intolerance and cerebral hyperperfusion.
Methods: The TOI of 27 patients was measured during CAS. The relationship between the TOI and ischemic intolerance or cerebral hyperperfusion was analyzed, and the cutoff TOI was calculated to predict their occurrence.
Results: Ischemic intolerance occurred in 5 patients during balloon protection. The TOI in the presence of ischemic intolerance was significantly lower than that without ischemic intolerance. The cutoff TOI to detect ischemic intolerance was 50% and that of the TOI change rate before and after balloon protection was 80%. The ischemic symptoms in all patients had resolved immediately after balloon deflation. The cerebral hyperperfusion phenomenon was detected using single-photon emission computed tomography in 4 patients. These patients showed a transient increase in the TOI immediately after CAS; however, none of these patients showed symptomatic cerebral hyperperfusion phenomenon. The cutoff TOI to detect cerebral hyperperfusion was 109% compared with the TOI before CAS.
Conclusion: Monitoring of the TOI using the NIRO system could be useful for the detection of ischemic intolerance and cerebral hyperperfusion during CAS and to prevent perioperative adverse events.
Keywords: Carotid artery stenting; Hyperperfusion; Near-infrared spectroscopy; Tissue oxygenation index.
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