Abstract
BackgroundHemodialysis (HD) with ultrafiltration (UF) in chronic renal replacement therapy is associated with hemodynamic instability, morbidity and mortality. Sublingual Sidestream Dark Field (SDF) imaging during HD revealed reductions in microcirculatory blood flow (MFI). This study aims to determine underlying mechanisms.MethodsThe study was performed in the Medical Centre Leeuwarden and the Lithuanian University of Health Sciences. Patients underwent 4-h HD session with linear UF. Nine patients were subject to combinations of HD and UF: 4 h of HD followed by 1 h isolated UF and 4 h HD with blood-volume-monitoring based UF. Primary endpoint: difference in MFI before and after intervention. During all sessions monitoring included blood pressure, heartrate and SDF-imaging. Trial registration number: NCT01396980.ResultsBaseline characteristics were not different between the two centres as within the HD/UF modalities. MFI was not different before and after HD with UF. Total UF did not differ between modalities. Median MFI decreased significantly during isolated UF [2.8 (2.5–2.9) to 2.5 (2.2–2.8), p = 0.03]. Baseline MFI of each UF session was correlated with MFI after the intervention (rs = 0.52, p = 0.006).ConclusionDuring HD with UF or isolated HD we observed no changes in MFI. This indicates that non-flow mediated mechanisms are of unimportance. During isolated UF we observed a reduction in MFI in conjunction with a negative intravascular fluid balance. The correlation between MFI before and after intervention suggests that volume status at baseline is a factor in microvascular alterations. In conclusion we observed a significant decrease of sublingual MFI, related to UF rate during chronic renal replacement therapy.
Highlights
Hemodialysis (HD) with ultrafiltration (UF) in chronic renal replacement therapy is associated with hemodynamic instability, morbidity and mortality
Intermittent hemodialysis (HD) with concomitant ultrafiltration (UF) in chronic renal replacement therapy is associated with hemodynamic instability, usually referred to as ‘intradialytic hypotension’
UF rate was significantly higher in isolated UF (p < 0.001) in comparison to combined HD/UF modalities (Table 3)
Summary
Hemodialysis (HD) with ultrafiltration (UF) in chronic renal replacement therapy is associated with hemodynamic instability, morbidity and mortality. Intermittent hemodialysis (HD) with concomitant ultrafiltration (UF) in chronic renal replacement therapy is associated with hemodynamic instability, usually referred to as ‘intradialytic hypotension’. The incidence of this phenomenon ranges between 30 and 90% depending on the definition on clinically relevant intradialytic hypotension. Apart from non-circulatory effects of HD this discordance represents a fundamental problem within the current clinical assumption that blood pressure is directly related to organ perfusion To overcome this problem direct visualisation and quantification of the sublingual microcirculation with a hand-held device has been suggested by Bemelmans and co-workers, as a noninvasive tool to trace ‘organ’ perfusion during HD [8]. Direct in-vivo microscopy of the sublingual area with sidestream dark field (SDF) imaging during HD revealed marked reductions in microcirculatory blood flow in the absence of intradialytic hypotension in the vast majority of patients. Are the observed microcirculatory alterations the result of UF, HD or a combination?
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