Specific hourly intradialytic RBV ranges are associated with lower all-cause mortality in chronic HD patients.

BackgroundCardiac disease is highly prevalent in hemodialysis (HD) patients. Decreased tissue perfusion, including cardiac, due to high ultrafiltration volumes (UFVs) is considered to be one of the drivers of cardiac dysfunction. While central venous oxygen saturation (ScvO2) is frequently used as an indicator of cardiac output in non-uremic populations, the relationship of ScvO2 and UFV in HD patients remains unclear. Our aim was to determine how intradialytic ScvO2 changes associate with UFV.MethodsWe conducted a 6-month retrospective cohort study in maintenance HD patients with central venous catheters as vascular access. Intradialytic ScvO2 was measured with the Critline monitor. We computed treatment-level slopes of intradialytic ScvO2 over time (ScvO2 trend) and applied linear mixed effects models to assess the association between patient-level ScvO2 trends and UFV corrected for body weight (cUFV).ResultsWe studied 6042 dialysis sessions in 232 patients. In about 62.4% of treatments, ScvO2 decreased. We observed in nearly 80% of patients an inverse relationship between cUFV and ScvO2 trend, indicating that higher cUFV is associated with steeper decline in ScvO2 during dialysis.ConclusionsIn most patients, higher cUFV volumes are associated with steeper intradialytic ScvO2 drops. We hypothesize that in a majority of patients the intradialytic cardiac function is fluid dependent, so that in the face of high ultrafiltration rates or volume, cardiac pre-load and consequently cardiac output decreases. Direct measurements of cardiac hemodynamics are warranted to further test this hypothesis.

Background/Aims: Neighborhood walkability is associated with indicators of health in the general population. We explored the association between neighborhood walkability and daily steps in hemodialysis (HD) patients. Methods: We measured daily steps over 5 weeks using Fitbit Flex (Fitbit, San Francisco, CA, USA) and retrieved Walk Score® (WS) data by patient’s home ZIP code (www.walkscore.com; 0 = poorest walkability; 100 = greatest walkability). Results: HD patients took a mean of 6,393 ± 3,550 steps/day (n = 46). Median WS of the neighborhood where they resided was 28. Patients in an above-median WS (n = 27) neighborhood took significantly more daily steps compared to those (n = 19) in a below-median WS neighborhood (7,514 ± 3,900 vs. 4,800 ± 2,228 steps/day; p < 0.001, t test). Daily steps and WS were directly correlated (R = 0.425; p = 0.0032, parametric test; R = 0.359, p = 0.0143, non-parametric test). Conclusion: This is the first study conducted among HD patients to indicate a direct relationship between neighborhood walkability and the actual steps taken. These results should be considered when designing initiatives to increase and improvise exercise routines in HD populations.

BackgroundThe pathophysiology of a paradoxical systolic blood pressure (SBP) rise during hemodialysis (HD) is not yet fully understood. Recent research indicated that 10% of chronic HD patients suffer from prolonged intradialytic hypoxemia. Since hypoxemia induces a sympathetic response we entertained the hypothesis that peridialytic SBP change is associated with arterial oxygen saturation (SaO2).MethodsWe retrospectively analyzed intradialytic SaO2 and peridialytic SBP change in chronic HD patients with arteriovenous vascular access. Patients were followed for 6 months. We defined persistent intradialytic hypertension (piHTN) as average peridialytic SBP increase ≥10 mmHg over 6 months. Linear mixed effects (LME) models were used to explore associations between peridialytic SBP change and intradialytic SaO2 in univariate and adjusted analyses.ResultsWe assessed 982 patients (29 872 HD treatments; 59% males; 53% whites). Pre-dialysis SBP was 146.7 ± 26.5 mmHg and decreased on average by 10.1 ± 24.5 mmHg. Fifty-three (5.7%) patients had piHTN. piHTN patients had lower intradialytic SaO2, body weight and interdialytic weight gain. LME models revealed that with every percentage point lower mean SaO2, the peridialytic SBP change increased by 0.46 mmHg (P < 0.001). This finding was corroborated in multivariate analyses.ConclusionWe observed an inverse relationship between intradialytic SaO2 and the blood pressure response to HD. These findings support the notion that hypoxemia activates mechanisms that partially blunt the intradialytic blood pressure decline, possibly by sympathetic activation and endothelin-1 secretion. To further explore that hypothesis, specifically designed prospective studies are required.

Background: Central venous oxygen saturation (ScvO₂) is correlated with cardiac output. In most patients, ScvO₂ declines during hemodialysis (HD) due to factors such as reduced preload, myocardial stunning, and intermittent arrhythmias. Previous research has shown that low ScvO₂ is associated with higher mortality in chronic HD patients. In this research, we tested the hypothesis that ScvO₂ 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. ScvO₂ was recorded 1× per minute during dialysis using the Crit-Line monitor. A 6-month baseline comprising at least 10 dialysis treatments with ScvO₂ recordings preceded a follow-up period of up to 3 years. The coefficient of variation (CV) of ScvO₂ (100 times the ratio of the standard deviation and mean of ScvO₂) served as a measure of ScvO₂ stability during baseline. Patients were stratified by median population CV of ScvO₂ 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 ScvO₂ and all-cause mortality during follow-up was further assessed by Cox analysis with a spline term for CV of ScvO₂. Results: The mean CV ± standard deviation of ScvO₂ 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 ScvO₂ > 5.3% was significantly associated with increased mortality. In Cox analysis with spline term, a CV of ScvO₂ >  11% was associated with a significantly increased HR for all-cause mortality. Conclusion: High ScvO₂ variability during dialysis is associated with increased all-cause mortality.

Background: Commencing hemodialysis (HD) using a catheter is associated with a higher risk of adverse outcomes, and early conversion from central-venous catheter (CVC) to arteriovenous fistula/graft (non-CVC) improves outcomes. We investigated CVC prevalence and conversion, and their effects on outcomes during the first year of HD in a multinational cohort of elderly patients. Methods: Patients ≥70 years from the MONDO Initiative who commenced HD between 2000 and 2010 in Asia-Pacific, Europe, North-, and South-America and survived at least 6 months were included in this investigation. We stratified by age (70-79 years [younger] vs. ≥80 years [older]) and compared access types (at first and last available date) and their changes. We studied the association between access at initiation and conversion, respectively, and all-cause mortality using Kaplan-Meier curve and Cox regression, and predicted the absence of conversion from catheter to non-CVC using adjusted logistic regression. Results: In 14,966 elderly, incident HD patients, survival was significantly worse when using a CVC at all times. In Europe, the conversion frequency from CVC to non-CVC was higher in the younger fraction. Conversion from non-CVC to CVC was associated with worsened outcomes only in the older fraction. Conclusion: These results corroborate the need for early HD preparation in the elderly HD population. Treatment of elderly patients who commence HD with a CVC should be planned considering aspects of individual clinical risk assessment. Differences in treatment practices in predialysis care specific to the elderly as a population may influence access care and conversion rate.

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Background Pre-dialysis systolic blood pressure (pre-HD SBP) and peridialytic SBP change have been associated with morbidity and mortality among hemodialysis (HD) patients in previous studies, but the nature of their interaction is not well understood. Methods We analyzed pre-HD SBP and peridialytic SBP change (calculated as post-HD SBP minus pre-HD SBP) between January 2001 and December 2012 in HD patients treated in US Fresenius Medical Care facilities. The baseline period was defined as Months 4–6 after HD initiation, and all-cause mortality was noted during follow-up. Only patients who survived baseline and had no missing covariates were included. Censoring events were renal transplantation, modality change or study end. We fitted a Cox proportional hazard model with a bivariate spline functions for the primary predictors (pre-HD SBP and peridialytic SBP change) with adjustment for age, gender, race, diabetes, access-type, relative interdialytic weight gain, body mass index, albumin, equilibrated normalized protein catabolic rate and ultrafiltration rate. Results A total of 172 199 patients were included. Mean age was 62.1 years, 61.6% were white and 55% were male. During a median follow-up of 25.0 months, 73 529 patients (42.7%) died. We found that a peridialytic SBP rise combined with high pre-HD SBP was associated with higher mortality. In contrast, when concurrent with low pre-HD SBP, a peridialytic SBP rise was associated with better survival. Conclusion The association of pre-HD and peridialytic SBP change with mortality is complex. Our findings call for a joint, not isolated, interpretation of pre-HD SBP and peridialytic SBP change.