Association of cerebral oxygenation with estimated glomerular filtration rate and cognitive function in chronic kidney disease patients without dialysis therapy

Background A decline in estimated glomerular filtration rate (eGFR) is reportedly associated with increased prevalence rates of cognitive impairment. However, data concerning the association between the cerebral saturation of oxygen (rSO(2)) and cognitive function of patients with chronic kidney disease (CKD) is limited. This study aimed to (i) elucidate the clinical factors associating with cerebral rSO(2) and (ii) investigate the association between cerebral rSO(2) and cognitive assessment in CKD patients. Methods A total of 40 CKD patients not requiring dialysis (26 men and 14 women; mean age, 61.0 +/- 2.7 years) were recruited. The numbers of patients at each CKD stage were as follows: G1, 5; G2, 8; G3a, 6; G3b, 5; G4, 11; and G5, 5. Cerebral rSO(2) was monitored at the forehead using the oxygen saturation monitor INVOS 5100C. The cognitive function of each patient was confirmed using the Mini-Mental State Examination (MMSE). Results Cerebral rSO(2) levels were significantly higher in CKD patients than in hemodialysis patients (63.8 +/- 1.5% vs. 44.9 +/- 2.2%, p < 0.001). Multiple regression analysis showed that cerebral rSO(2) was independently associated with eGFR (standardized coefficient: 0.530), serum albumin concentration (standardized coefficient: 0.365), and serum sodium concentration (standardized coefficient: 0.224). Furthermore, MMSE showed a significantly positive correlation with cerebral rSO(2) (r = 0.624, p < 0.001). Conclusions Cerebral rSO(2) was affected by eGFR and serum albumin and sodium concentrations in CKD patients. Furthermore, cerebral rSO(2) monitoring, which reflected MMSE scores, might be a useful method for assessing cognitive function in CKD patients.