#6009 MUSCLE OXYGENATION AND MICROVASCULAR REACTIVITY ACROSS DIFFERENT STAGES OF CHRONIC KIDNEY DISEASE: A NEAR-INFRARED SPECTROSCOPY STUDY

Abstract

Abstract Background and Aims Previous studies in chronic kidney disease (CKD) showed that vascular dysfunction in different circulatory beds is progressively deteriorating with CKD severity. This study evaluated muscle oxygenation and microvascular reactivity at rest, during an occlusion-reperfusion maneuver, and during exercise in patients with pre-dialysis CKD versus controls, as well as between different CKD stages Method Continuous measurement of muscle oxygenation [tissue saturation index (TSI%)] via near-infrared-spectroscopy at rest, during occlusion-reperfusion, and during a 3-min handgrip exercise(at 35% of maximal-voluntary-contraction). Aortic pulse wave velocity (PWV) and carotid intima-media thickness (cIMT) were also recorded. Results Resting muscle oxygenation did not differ among the study groups (controls: 64.3±2.9 stage-2: 63.8±4.2stage-3a: 64.1±4.1 stage-3b: 62.3±3.3 stage-4: 62.7±4.3%; p = 0.6). During occlusion, no significant differences among groups were detected in TSIocl magnitude- and occlusion-slope. However, during reperfusion, theTSImax and the hyperemic response were significantly lower in groups of patients with more advanced CKD stages (controls: 11.2±3.7 stage-2: 8.3±4.6 stage-3: 7.8±5.5 stage-3b: 7.3±4.4 stage-4: 7.2±3.3; p = 0.04). During handgrip exercise, muscle oxygenation (TSIaverage-decline) was marginally lower in CKD patients than controls, but no significant differences were detected between CKD stages. Conclusion Although no differences were observed in muscle oxygenation at rest and during occlusion, the microvascular hyperemic response during reperfusion was significantly impaired in CKD and deteriorated in more advanced CKD stages. This impaired ability of microvasculature to respond to stimuli may be a crucial component of the adverse vascular profile of CKD patients and may contribute to exercise intolerance