Changes in cerebral oxygenation during hemodialysis before and after carotid artery stenting

A 68-year-old man received hemodialysis (HD) for the treatment of end-stage renal failure for 6 years. Five years prior to carotid artery stenting (CAS), a neck ultrasound performed to screen for carotid atherosclerosis revealed an asymptomatic right internal carotid artery stenosis. One month prior, the stenotic lesion progressed to 74% by cerebral angiography; therefore, CAS was performed. To evaluate the influence of right internal carotid artery stenosis on the intradialytic cerebral circulation and oxygenation, cerebral regional oxygen saturation (rSO(2)) at bilateral forehead was measured using the INVOS 5100c oxygen saturation monitor (Covidien Japan, Japan) during HD before and after CAS. Before CAS, right cerebral rSO(2) was maintained during HD, whereas left cerebral rSO(2) gradually increased from the initiation to end of HD. However, the differences of intradialytic cerebral rSO(2) changes between bilateral sides disappeared after CAS. In the present case, before CAS, the intradialytic increase in left cerebral rSO(2) might reflect the increase in the left cerebral blood flow to compensate for the ultrafiltration-associated decreases in the right cerebral blood flow and perfusion pressure. Furthermore, the preserved right cerebral rSO(2) before CAS might reflect the mechanism maintaining the right cerebral blood flow from the collateralized circle of Willis during HD. Throughout our experience, cerebral oxygenation monitoring during HD might disclose intradialytic changes in cerebral blood flow distribution between the ipsilateral and contralateral side in HD patients with carotid artery stenosis.