Improvement in exercise duration and capacity after conversion to nocturnal home haemodialysis

Background. Patients with end-stage renal disease (ESRD) have a reduced exercise capacity as assessed by peak oxygen uptake (VO2peak). Nocturnal haemo- dialysis (NHD) augments uraemic clearance and vascular responsiveness to nitric oxide and lowers blood pressure (BP) and peripheral resistance. Methods. To assess the impact of NHD on exercise duration and capacity, 13 consecutive ESRD patients (age: 41 � 3; (meanSEM)) and healthy normal subjects (n ¼ 14) matched for age and body mass index exercised to peak effort (VO2peak) as determined by open-circuit spirometry during a graded cycle ergometer test with a ramp increase in work rate (by 17 watts/min). Results. Exercise was performed before, 2 and 3-6 months after conversion from conventional haemodia- lysis (CHD) (3 sessions per week; 4 h per session) to NHD (5-6 sessions per week; 6-8 h per session). Exercise duration increased progressively (from 617 � 50 (CHD) to 634 � 47 (NHD 2 months) to 682 � 55 (NHD 3-6 months), P ¼ 0.03) as did exercise capacity, expressed as percent of predicted (based on age, sex and body size) VO2peak, (from 66 � 8 (CHD) to 72 � 6 (NHD 2 months) to 75 � 6% (NHD 3-6 months), P < 0.05). Conclusion. Enhanced uraemia control by NHD improved both exercise duration and capacity. When coupled with augmented uraemia management, an increase in physical activity, perhaps due to more effective oxygen delivery or improved muscle metabo- lism, has the potential to improve the quality of life of patients with ESRD.