Cardiac autonomic function during intradialytic exercise training

Objectives: Cardiac autonomic nervous system (ANS) dysfunction is a common feature in patients receiving hemodialysis (HD) therapy, whilst is associated with an increased risk of ventricular arrhythmias and sudden cardiac death. The aim of this study is to investigate and compare the hemodynamic changes and responses of ANS function in HD patients using pupillometry and Heart Rate Variability (HRV) parameters. Methods: Sixteen chronic kidney diseases (CKD) patients receiving HD (52.18 ± 17.7 years) underwent both pupillometric measurements using a portable handheld pupil-measuring device and standard HRV analysis pre HD, every hour and 30 min post-HD session under two different scenarios: at rest while the patient resting at HD bed and when the patient performed a single bout of intradialytic aerobic exercise lasting for 45 min during the second hour of the HD therapy. Results: No significant changes in ANS values were observed in neither of the pupillometric and the HRV values pre HD, for each hour and post-HD session. HRV parameters were significantly correlated with pupillometric parameters at pre HD and immediately after the single bout of intradialytic exercise. ANS activity did not differ during the conventional HD session and during the session included intradialytic exercise. Moreover, sympatho-vagal balance indices deriving from pupillometric assessment showed beneficial changes after the exercise event. Conclusion: Pupillometry is a promising and robust technique with fewer artifacts compared to HRV especially in studies involving exercise sessions. Thus, pupillometry can be used as a complementary tool in the evaluation of cardiac autonomic dysfunction.