Changes in frontal lobe regional oxygen saturation in cases of intradialytic hypotension

Dialysis patients are at increased risk of cerebrovascular disease and cognitive dysfunction. Many studies have suggested that cerebral blood flow declines during hemodialysis (HD), and HD procedures themselves may have deleterious effects on the brain. Here, we report 3 cases of intradialytic hypotension, in which frontal lobe regional oxygen saturation (FL‒rSO2), which is used as a proxy for cerebral blood flow, was measured. Case 1 involved a 76‒year‒old male with diabetic nephropathy, who underwent online hemodiafiltration. Two hours after the start of dialysis, two rapid reductions in blood pressure and a reduction in FL‒rSO2 were observed. Case 2 involved a 65‒year‒old female with chronic glomerulonephritis, who underwent intermittent infusion hemodiafiltration (slow‒IHDF) with 50 mL of fluid replacement every 15 minutes. Her blood pressure and blood volume (BV) remained low from the start of the dialysis, while her FL‒rSO2 remained stable between 40％ and 50％. Although her BV decreased slightly, her blood pressure decreased from 3 hours after the start of the dialysis, and her FL‒rSO2 changed in response to the substitution of the IHDF fluid. The mechanism responsible for regulating cerebral blood flow during dialysis is complex. Therefore, it is difficult to use blood pressure or BV as indicators of cerebral blood flow. Monitoring FL‒rSO2 during dialysis may be useful for cerebral circulation management.