Association of Central Venous Oxygen Saturation Variability and Mortality in Hemodialysis Patients

Background: Central venous oxygen saturation (ScvO(2)) is correlated with cardiac output. In most patients, ScvO(2) declines during hemodialysis (HD) due to factors such as reduced preload, myocardial stunning, and intermittent arrhythmias. Previous research has shown that low ScvO(2) is associated with higher mortality in chronic HD patients. In this research, we tested the hypothesis that ScvO(2) variability is associated with all-cause mortality. Methods: We conducted a retrospective study in 232 chronic HD patients with central venous catheter as vascular access. ScvO(2) was recorded 1x per minute during dialysis using the Crit-Line monitor. A 6-month baseline comprising at least 10 dialysis treatments with ScvO(2) recordings preceded a follow-up period of up to 3 years. The coefficient of variation (CV) of ScvO(2) (100 times the ratio of the standard deviation and mean of ScvO(2)) served as a measure of ScvO(2) stability during baseline. Patients were stratified by median population CV of ScvO(2) during baseline, and survival during follow-up was compared between the 2 groups by Kaplan Meier and multivariate Cox analysis. The association between CV of ScvO(2) and all-cause mortality during follow-up was further assessed by Cox analysis with a spline term for CV of ScvO(2). Results: The mean CV +/- standard deviation of ScvO(2) in our population was 6.1 +/- 2.7% and the median was 5.3%. Univariate Kaplan-Meier analysis (p = 0.043) and multivariate Cox analysis (hazard ratio [HR] 1.16; p = 0.0005) indicated that a CV of ScvO(2) > 5.3% was significantly associated with increased mortality. In Cox analysis with spline term, a CV of ScvO(2) > 11% was associated with a significantly increased HR for all-cause mortality. Conclusion: High ScvO(2) variability during dialysis is associated with increased all-cause mortality. (c) 2018 S. Karger AG, Basel