Ultrafiltration rate is an important determinant of microcirculatory alterations during chronic renal replacement therapy

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 (r s = 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.

Effect of ultrafiltration on placental‐fetal blood flow in pregnancy of woman undergoing chronic hemodialysis

“…However, it has been demonstrated that isolated UF or in combination with HD leads to significant microvascular blood flow decrease at the end of HD session and this repeated event during pregnancy can result in placental chronic ischemic lesions and may predispose to prematurity and low birth weight. And high UF rate increase hemodynamic instability and intradialytic hypotension episodes, decrease placental blood flow and can produce acute ischemic injury secondary to a rapid withdrawal of large amounts of intravascular fluid .…”

What lies downstream: Cellular oxygen delivery during hemodialysis

“…Another small study confirmed that the density and proportion of perfused vessels fell significantly over hemodialysis, and that microvascular dysfunction was not reflected in blood pressure or arterial saturations . A third study was only able to replicate the findings of reduced sublingual perfusion in patients undergoing rapid isolated ultrafiltration, perhaps due to differences in baseline volume status …”

“…34 A third study was only able to replicate the findings of reduced sublingual perfusion in patients undergoing rapid isolated ultrafiltration, perhaps due to differences in baseline volume status. 35 Videomicroscopy techniques, including laser Doppler of microvessels, have also been applied to the skin during hemodialysis. 36,37 Numbers are small, and skin microcirculation is unlikely to represent visceral microvasculature.…”

Monitoring skin blood flow to rapidly identify alterations in tissue perfusion during fluid removal using continuous veno-venous hemofiltration in patients with circulatory shock

“…When spontaneous diuresis is inadequate, fluid removal using continuous veno-venous hemodialysis (CVVH) is a valuable therapeutic option to eliminate excess fluid [4,5]. However, aggressive fluid removal can cause hemodynamic compromise resulting in tissue hypoperfusion, and necessitating cessation of fluid removal despite the persistence of tissue edema [2,3,[6][7][8]. In severe cases, hypotension may develop, leading to impaired organ function and increased mortality [9][10][11].…”