Microvascular Dilatation after Haemodialysis Is Determined by the Volume of Fluid Removed and Fall in Mean Arterial Pressure

Abstract

Background/Aims: The effects of haemodialysis on the microcirculation are poorly understood. This study examined the changes in small vessel calibre. Methods: 24 patients (including 12 males, median age 62.5 years, range 30–87) underwent digital retinal photography immediately before and after routine haemodialysis. Arteriolar and venular calibres were measured from the images by a trained grader using a highly reproducible, computer-assisted method. Results: Patients had an average 2.0 ± 0.3 litres of fluid removed with dialysis, and their mean arterial blood pressure fell by 6.8 mm Hg (CI 13.8–0.2, p = 0.06). Retinal arteriole calibre did not change (mean difference 2.3 µm, CI –1.1 to 5.7, p = 0.17) but the venules dilated (mean difference 12.7 µm, CI 7.3–18.3, p < 0.001). Calibre returned to baseline by 2 h. Venules dilated less in diabetics than non-diabetics (mean difference –6.2 µm, CI –9.6 to –2.9, p < 0.01). Retinal venular dilatation correlated positively with the volume of fluid removed per kilogramme body weight (5.9, CI 0.2–11.5, p = 0.04), and negatively with the fall in mean arterial pressure (–0.36, CI –0.72 to –0.01, p < 0.05) after adjusting for age, gender, diabetes and dyslipidaemia. Conclusion: Haemodialysis is associated with systemic venular dilatation.

Changes in skeletal muscle microcirculation after a hemodialysis session correlates with adequacy of dialysis

“…The increased cell metabolism seen at the end of a HD session could be caused by the acute withdrawal of liquid taking place during HD, which reduces interstitial edema and the external pressure on the microcirculation, also triggering an increased dilatation of the peripheral capillaries. 19 Vascular dilatation can be further provoked by complement activation and endothelial production of cytokines and prostacyclins, which occurs during HD, 17,20 as well as by administration of vasodilating antihypertensives, 4 which were common in our patient sample (70% of the ESRD patients were on calcium antagonist therapy). The improvement in thenar cell metabolism may also be related to the increase in oxygenated hemoglobin levels at the end of the HD session.…”

“…Patients with ESRD are permanently exposed to uremic toxins which are poorly removed by HD and induce endothelium-dependent vasodilatation, elevated soluble biomarkers of endothelial dysfunction, and increased oxidative stress. 19,28,29 Traditional risk factors, such as age and hypertension, have been associated with changes in endothelial function, 30,31 and therefore might be responsible for modification of vascular elasticity. Further, hypertensive patients on HD may have more severe vascular damage, because in parallel with progression of endothelial impairment, these patients show a decrease in total vascular dilatative capacity.…”

Optical coherence tomography angiography analysis of changes in the retina and the choroid after haemodialysis

“…Tow et al . demonstrated that the central retinal venules were maximally dilated immediately after haemodialysis by measuring the retinal vascular calibre on the retinal fundus photograph 41 . These changes may influence the results of our study.…”

Microvascular Disease After Renal Transplantation

“…Moderate features were hemorrhage, microaneurysms, cotton wool spots and exudates, and severe retinopathy was characterized by optic disc swelling. However these abnormalities are not permanent, and hemorrhage, exudates and papilledema may resolve, and small vessel caliber, even in CKD5, can increase in response to stressors such as dialysis [26]. Improvements in small vessel damage could occur post-transplantation because of better blood pressure control and resolution of renal failure-induced inflammation.…”