Amplitude of Tissue Oxygenation Index Change Predicts Cerebral Hyperperfusion Syndrome During Carotid Artery Stenting.

Abstract

OBJECTIVE: Hyperperfusion syndrome (HPS) after carotid artery stenting (CAS) is a rare but serious complication. HPS is associated with preoperative hemodynamic impairment as the result of poor collateral flow and intraoperative cerebral ischemia. Filter-type embolic protection devices maintain anterograde carotid flow during CAS and prevent HPS somewhat. The early treatment of patients undergoing CAS and at risk for HPS is essential. Near-infrared spectroscopy allows noninvasive, real-time measurement of frontal lobe regional cerebral O2 saturation (TOI; tissue oxygenation index). METHODS: The perioperative amplitude of TOI was monitored in 130 patients undergoing CAS while using a filter-type embolic protection device. Patients were divided retrospectively into good (n = 110) and poor/no crossflow groups (n = 20), and we compared the amplitude of the TOI change, correlation with ipsilateral regional cerebral blood flow, and clinical results. RESULTS: The incidence of HPS was significantly greater in the poor/no crossflow group (P = 0.019). In 2 patients with HPS, the amplitude of the TOI change was V-shaped, with a decrease after postdilatation and an increase above baseline 5 minutes after reperfusion. The TOI/baseline ratio was significantly decreased after internal carotid artery occlusion for postdilatation in the ipsilateral hemisphere in the poor/no crossflow group (P < 0.05). Significant linear correlations were observed between TOI/baseline ratio changes and preoperative cerebrovascular reactivity and the postoperative asymmetry index (r = -0.346, P = 0.002, r = 0.613, P < 0.001, respectively). CONCLUSIONS: The amplitude of the TOI change measured by near-infrared spectroscopy was an excellent predictor of cerebral HPS after CAS.