Spiroergometric performance of children and adolescents with chronic renal failure

Abstract

Maximal physical performance (Wmax), maximal oxygen consumption ($\dot V$O₂max), maximal carbon dioxide production ($\dot V$CO₂max) and blood lactate (L) levels were measured in 34 paediatric patients with chronic renal failure (CRF) and 25 controls by spiroergometric testing on a bicycle ergometer. No patient was treated with erythropoietin. The workload was increased step-wise by 0.5 W/3 min up to a Wmax determined from the attainment of$\dot V$O₂max. In patients on conservative treatment (CT), on haemodialysis (HD) and after transplantation (TP) median Wmax per kilogram body weight was reduced to 76%, 73% and 73% of controls (C), respectively. In CT and HD patients$\dot V$O₂max and$\dot V$CO₂max were decreased to an even higher extent. The ventilatory anaerobic threshold, calculated from the levelling off of the respiratory equivalent$\dot V$E/$\dot V$O₂) during increasing workload, was only slightly higher in patients than in C when related to Wmax (NS). The physiological rise in L during exercise was blunted in CRF; 72% of patients on CT or HD did not exceed the expected threshold L level of 4 mmol/l; after TP the L changes normalized. The findings indicate that most children and adolescents with CRF are able to attain maximal physical performance but both the aerobic and the anaerobic capacity are often reduced. Preliminary findings indicate that treatment of renal anaemia with erythropoietin is able to considerably improve Wmax and$\dot V$O₂max in paediatric HD patients.