#1551 The presence of proteinuria is associated with impaired cerebral oxygenation during exercise in chronic kidney disease

Abstract

Abstract Background and Aims Cognitive impairment and reduced exercise tolerance are common in patients with chronic kidney disease (CKD), in part due to reduced brain function. Cerebral perfusion and oxygenation are significant determinants of brain activation and have been shown to be significantly impaired in CKD. This analysis aims to examine the impact of proteinuria on cerebral oxygenation during a mild physical stress in patients with pre-dialysis CKD. Method 66 patients with CKD stage 2-4 were included in this post-hoc analysis; 24-h urine samples were used for evaluation of proteinuria. All participants underwent a 3-min intermittent handgrip exercise (HG) at 35% of their maximal voluntary contraction. Changes in cerebral oxygenation (oxyhemoglobin-O2Hb) and deoxyhemoglobin-HHb) and regional blood volume (total hemoglobin-tHb) were continuously recorded during HG-exercise by near-infrared spectroscopy (NIRS). Results No significant differences between the 2 groups were detected in age (proteinuric vs nonproteinuric: 68.4 ± 10.6 vs 67.2 ± 10.8; p = 0.676), eGFR (41.3 ± 18.9 vs 46.3 ± 14.8; p = 0.248) and BMI (28.4 ± 4.9 vs 28.1 ± 4.8; p = 0.803). The MMSE score (proteinuric vs nonproteinuric: 28.0 ± 1.6 vs 28.0 ± 1.7; p = 0.938) and MVC (22.3 ± 7.0 vs 23.9 ± 7.5; p = 0.416) were not significantly different between groups. The average response in cerebral oxygenation during exercise was lower in patients with proteinuric CKD (O2Hb: 1.02 ± 0.87 vs 1.61 ± 0.95; p = 0.018 and diffO2Hb 1.53 ± .97 vs 2.07 ± 1.25; p = 0.065). The average tHb response (index of regional-blood-volume) was also lower in patients with proteinuria (0.51 ± 1.08 vs 1.16 ± 0.92 p = 0.013); however, no differences in HHb (-0.50 ± 0.55 vs -0.45 ± 0.54; p = 0.717) –an index of oxygen extraction capacity- among groups were detected. In univariate linear analysis the level of proteinuria did not show significant correlations with NIRS parameters. Conclusion The presence and not the level of proteinuria is associated with impaired brain activation during a mild physical task in patients with predialysis CKD. Future studies evaluating the role of proteinuria in the decline of cerebral function and cognitive impairment are needed.