Acute Effect of Moderate-Intensity Interval Intradialytic Exercise on Cerebral Oxygenation in Hemodialysis Patients: A Randomized Crossover Trial.

Background: Cognitive dysfunction in hemodialysis (HD) patients is associated with decreased regional cerebral oxygenation (rSO2). Intradialytic exercise improves cognitive function; nonetheless, the acute effect of intradialytic exercise on cerebral circulation remains unknown. This study aimed to evaluate the acute effect of intradialytic exercise on rSO2 during HD.

Methods: This single-center, open-label, randomized crossover trial included 20 HD patients. Patients received the control condition as usual care and the intradialytic exercise condition in random order. The intradialytic exercise condition involved the performance of anaerobic threshold-intensity interval exercise for 35 min. Cerebral oxygenation (rSO2, oxygenated hemoglobin, deoxygenated hemoglobin, and total hemoglobin) in the prefrontal cortex was measured using near-infrared spectroscopy during HD. Cardiovascular responses, including the heart rate, cardiac index, mean arterial pressure, and blood gas, were also assessed. The two conditions were compared using two-way repeated-measures analysis of variance.

Results: The analysis included 16 patients, four of whom were excluded because of artifacts in the cerebral oxygenation data. The rSO2 (P<0.001), oxygenated hemoglobin (P<0.001), and total hemoglobin (P=0.004) showed significant interactions and were significantly increased at end of exercise (rSO2 1.3%, 95%CI [0.5, 2.1]; oxygenated hemoglobin 0.01 mM, 95%CI [0.00, 0.02]; total hemoglobin 0.01 mM, 95%CI [0.00, 0.03]) and 15-min after exercise (rSO2 1.1%, 95%CI [0.2, 2.0]; oxygenated hemoglobin 0.01 mM, 95%CI [0.00, 0.03]; total hemoglobin 0.02 mM, 95%CI [0.00, 0.03]) in the intradialytic exercise condition compared with the control condition. The rSO2 at the end of HD in the control condition was significantly decreased compared with that during pre-HD (-1.5%, 95%CI [-2.7, -0.3]), but not in the intradialytic exercise condition (-1.2%, 95%CI [-2.8, 0.5]).

Conclusions: Intradialytic exercise significantly increased rSO2 during and after exercise and improved rSO2 to the same extent as pre-dialysis.