Background Both baseline fluid overload (FO) and fluid depletion are associated with increased mortality risk and cardiovascular complications in haemodialysis patients. Fluid status may vary substantially over time, and this variability could also be associated with poor outcomes. Methods In our retrospective cohort study, including 4114 haemodialysis patients from 34 Romanian dialysis units, we investigated both all-cause and cardiovascular mortality risk according to baseline pre- and post-dialysis volume status, changes in pre- and post-dialysis fluid status during follow-up (time-varying survival analysis), pre–post changes in volume status during dialysis and pre-dialysis fluid status variability during the first 6 months of evaluation. Results According to their pre-dialysis fluid status, patients were stratified in the following groups: normovolaemic with an absolute FO (AFO) compartment between −1.1 and 1.1 L, fluid depletion with an AFO below −1.1 L, moderate FO with an AFO compartment >1.1 but <2.5 L and severe FO with the AFO compartment >2.5 L. Baseline pre-dialysis FO and fluid depletion patients had a significantly elevated risk of all-cause mortality risk {hazard ratio [HR] 1.53 [95% confidence interval (CI) 1.22–1.93], HR 2.04 (95% CI 1.59–2.60) and HR 1.88 (95% CI 1.07–3.39) for moderate FO, severe FO and fluid depletion, respectively}. In contrast, post-dialysis fluid depletion was associated with better survival [HR 0.71 (95% CI 0.57–0.89)]. Similar results were found when using changes in pre- or post-dialysis fluid status during follow-up (time-varying values): FO patients had an increased risk of all-cause [moderate FO: HR 1.39 (95% CI 1.11–1.75); severe FO: HR 2.29 (95% CI 2.01–3.31] and cardiovascular (CV) mortality [moderate FO: HR 1.34 (95% CI 1.05–1.70); severe FO: HR 2.34 (95% CI 1.67–3.28)] as compared with normohydrated patients. Using pre–post changes in volume status during dialysis, we categorized the patients into six groups: Group 1, AFO <−1.1 L pre- and post-dialysis; Group 2, AFO between −1.1 and 1.1 L pre-dialysis and <−1.1 L post-dialysis (the reference group); Group 3, AFO between −1.1 and 1.1 L pre- and post-dialysis; Group 4, AFO >1.1 L pre-dialysis and <−1.1 L post-dialysis; Group 5, AFO >1.1 L pre-dialysis and between −1.1 and 1.1 L post-dialysis; Group 6, AFO >1.1 L pre- and post-dialysis. Using the baseline values, only patients in Groups 1, 5 and 6 maintained an increased risk for all-cause mortality as compared with the reference group. Additionally, CV mortality risk was significantly higher for patients in Groups 5 and 6. When we applied the time-varying analysis, patients in Groups 1, 5 and 6 had a significantly higher risk for both all-cause and CV mortality risk. In the last approach, the highest risk for the all-cause mortality outcome was observed for patients with high-amplitude fluctuation during the first 6 months of evaluation [HR 2.75 (95% CI 1.29–5.84)]. Conclusion We reconfirm the association between baseline pre- and post-dialysis volume status and mortality in dialysis patients; additionally, we showed that greater fluid status variability is independently associated with higher mortality.

IntroductionChronic heart failure (HF) represents a major global public health problem, and despite significant advances in diagnosis and management over the past two decades, HF patients still have a poor prognosis. The aim of the study was to evaluate the relationship between lung congestion, as assessed by lung ultrasonography (LUS), bioimpedance spectroscopy, body fluid compartments, and echocardiographic parameters, and to determine the effect of these associations on all-cause mortality in HF patients.Material and methodsEligible patients with a left ventricular ejection fraction (LVEF) below 45% were identified via daily echocardiography assessments. Lung ultrasonography was performed with patients in the supine position, for a total of 28 sites per complete examination. The extracellular water (ECW) was determined using a BIS device.ResultsOur study included 122 patients (67.2% males) with a mean age of 67.2 years. In the multivariable linear regression analysis, including all the univariable predictors of lung congestion, only New York Heart Association (NYHA) class, ECW, estimated glomerular filtration rate (eGFR), and LVEF levels maintained an independent association with the number of B-lines. During the follow-up, 33 patients died. In multivariable Cox analysis, a B-line number of at least 15 remained significantly associated with all-cause mortality, independently of age, sex, diabetes, LVEF, estimated glomerular filtration rate, C-reactive protein, N-terminal pro-brain natriuretic peptide, or ECW values (adjusted HR = 3.84, 95% CI: 1.12–13.09).ConclusionsWe show for the first time in HF patients that pulmonary congestion, as assessed by LUS, is associated with the severity of NYHA class, LVEF, eGFR, and ECW, and it identifies those at increased risk of death.