Abstract
Long interdialytic interval in thrice-weekly hemodialysis is associated with excess cardiovascular and all-cause mortality risk. Impaired cardiorespiratory fitness is a strong predictor of mortality in hemodialysis. This study investigated differences in cardiorespiratory fitness assessed with cardiopulmonary exercise testing (CPET) between the end of the 2-day and the 3-day interdialytic interval. A total of 28 hemodialysis patients, randomized in two different sequences of evaluation underwent CPET and spirometry examination at the end of the 2-day and the 3-day intervals. The primary outcome was the difference in oxygen uptake at peak exercise [VO2peak(ml/kg/min)] assessed with CPET. Volume status was assessed with interdialytic-weight-gain, lung-ultrasound, bioimpedance spectroscopy (BIS), and inferior vena cava measurements. A total of 14 age- and sex-matched controls were also evaluated. Comparisons of changes in parameters of interest were performed with paired or independent t-tests, or relevant non-parametric tests, as appropriate. Bivariate correlation analyses and generalized-linear-mixed-models were employed to examine associations between changes in CPET parameters and volume indices. Hemodialysis patients at the end of both 2-day and 3-day intervals presented lower values in all major CPET parameters than controls. VO2peak(ml/kg/min) was significantly higher at the end of the 2-day than the 3-day interval (15.2±4.2 vs 13.6±2.8;p<0.001); similar were the results for VO2peak(ml/min) (1188±257 vs 1074±224;p<0.001) and VO2peak(%predicted) (58.9±9.2 vs 52.3±8.6;p<0.001). Numerical but no statistically significant differences were detected in VO2-anaerobic-threshold(ml/kg/min) and VO2-anaerobic-threshold(ml/min) between the two time-points. Maximal work load (90.1±23.2 vs 79.3±25.1;p<0.001), exercise duration, heart rate at peak exercise and oxygen pulse also showed lower values at the end of the 3-day interval. Forced-expiratory-volume in 1 second levels were similar between the two evaluations. Generalized-linear-mixed-model analysis including interdialytic-weight-gain as random covariate attenuated the observed differences in VO2peak(ml/kg/min). Changes in BIS-derived overhydration indexes were moderately correlated with changes of VO2peak(ml/kg/min). The 3-day interval was associated with further impairment of VO2 at peak exercise. This effect was predominantly driven by excess fluid accumulation during the extra interdialytic day.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have