Background. Satisfactory haemodialysis (HD) vascular access flow (Qa) is necessary for dialysis adequacy. High Qa is postulated to increase cardiac output (CO) and cause high-output cardiac failure. Aim of the present prospective study was to evaluate the relationship between Qa of arteriovenous fistulas (AVFs) and CO in order to have a closer insight into this scarcely explored aspect of HD pathophysiology.

COVID-19, a disease caused by a novel coronavirus, is a major global human threat that has turned into a pandemic. This novel coronavirus has specifically high morbidity in the elderly and in comorbid populations. Uraemic patients on dialysis combine an intrinsic fragility and a very frequent burden of comorbidities with a specific setting in which many patients are repeatedly treated in the same area (haemodialysis centres). Moreover, if infected, the intensity of dialysis requiring specialized resources and staff is further complicated by requirements for isolation, control and prevention, putting healthcare systems under exceptional additional strain. Therefore, all measures to slow if not to eradicate the pandemic and to control unmanageably high incidence rates must be taken very seriously. The aim of the present review of the European Dialysis (EUDIAL) Working Group of ERA-EDTA is to provide recommendations for the prevention, mitigation and containment in haemodialysis centres of the emerging COVID-19 pandemic. The management of patients on dialysis affected by COVID-19 must be carried out according to strict protocols to minimize the risk for other patients and personnel taking care of these patients. Measures of prevention, protection, screening, isolation and distribution have been shown to be efficient in similar settings. They are essential in the management of the pandemic and should be taken in the early stages of the disease.

Several studies already stressed the importance of haemodialysis (HD) time in the removal of uraemic toxins. In those studies, however, also the amount of dialysate and/or processed blood was altered. The present study aimed to investigate the isolated effect of the factor time t (by processing the same total blood and dialysate volume in two different time schedules) on the removal and kinetic behaviour of some small, middle and protein-bound molecules. The present study had a crossover design: 11 stable anuric HD patients underwent two bicarbonate HD sessions (~ 4 and ~ 8 h) in a random sequence, at least 1 week apart. The GENIUS single-pass batch dialysis system and the high-flux FX80 dialysers (Fresenius Medical Care, Bad Homburg, Germany) were used. The volume of blood and dialysate processed, volume of ultrafiltration, and dialysate composition were prescribed to be the same. For each patient, blood was sampled from the arterial line at 0, 60, 120, 180 and 240 min (all sessions), and at 360 and 480 min (8-h sessions). Dialysate was sampled at the end of HD from the dialysate tank. The following solutes were investigated: (i) small molecules: urea, creatinine, phosphorus and uric acid; (ii) middle molecule: β(2)M; and (iii) protein-bound molecules: homocysteine, hippuric acid, indole-3-acetic acid and indoxyl sulphate. Total solute removals (solute concentration in the spent dialysate of each analyte × 90 L - the volume of dialysate) (TSR), clearances (TSR of a solute/area under the plasma water concentration time curve of the solute) (K), total cleared volumes (K × dialysis time) (TCV), and dialyser extraction ratios (K/blood flow rate) (ER) were determined. The percent differences of TSR, K, TCV and ER between 4- and 8-h dialyses were calculated. Single-pool Kt/Vurea, and post-dialysis percent rebounds of urea, creatinine and β(2)M were computed. TSR, TCV and ER were statistically significantly larger during prolonged HD for all small and middle molecules (at least, P < 0.01). Specifically, the percent increases of TSR (8 h vs 4 h) were: for urea 22.6.0% (P < 0.003), for creatinine 24.8% (P < 0.002), for phosphorus 26.6% (P < 0.001), and for β(2)M 39.2% (P < 0.005). No statistically significant difference was observed for protein-bound solutes in any of the parameters being studied. Single-pool Kt/Vurea was 1.41 ± 0.19 for the 4-h dialysis sessions and 1.80 ± 0.29 for the 8-h ones. The difference was statistically significant (P < 0.0001). Post-dialysis percent rebounds of urea, creatinine and β(2)M were statistically significantly greater in the 4-h dialysis sessions (at least, P < 0.0002). The present controlled study using a crossover design indicates that small and middle molecules are removed more adequately from the deeper compartments when performing a prolonged HD, even if blood and dialysate volumes are kept constant. Hence, factor time t is very important for these retention solutes. The kinetic behaviour of protein-bound solutes is completely different from that of small and middle molecules, mainly because of the strength of their protein binding.

A significant proportion of patients who suffer from atrial fibrillation and are in need of thromboembolic protection are not treated with oral anticoagulation or discontinue this treatment shortly after its initiation. This undertreatment has not improved sufficiently despite the availability of direct oral anticoagulants which are associated with less major bleeding than vitamin K antagonists. Multiple reasons account for this, including bleeding events or ischaemic strokes whilst on anticoagulation, a serious risk of bleeding events, poor treatment compliance despite best educational attempts or aversion to drug therapy. An alternative interventional therapy, which is not associated with long-term bleeding and is as effective as vitamin K anticoagulation, was introduced over 20 years ago. Because of significant improvements in procedural safety over the years left atrial appendage closure, predominantly achieved using a catheter-based, device implantation approach, is increasingly favoured for the prevention of thromboembolic events in patients who cannot achieve effective anticoagulation. This management strategy is well-known to the interventional cardiologist/electrophysiologist but is not more widely appreciated within cardiology or internal medicine. This article introduces the devices and briefly explains the implantation technique. The indications and device follow-up are more comprehensively described. Almost all physicians who care for adult patients will have many with atrial fibrillation. This practical guide, written within guideline/guidance boundaries, is aimed at those non-implanting physicians who may need to refer patients for consideration of this new therapy, which is becoming increasingly popular.

COVID-19, a disease caused by a novel coronavirus (SARS-CoV-2), is a major global threat that has turned into a pandemic. Despite the emergence of multiple vaccination alternatives and developing therapeutic options, dramatic short- and long-term clinical outcomes have been recorded with more than 250 million infected people and over 5 million deaths as of November 2021. COVID-19 presents various respiratory, cardiovascular, neuropsychiatric, musculoskeletal and kidney features during the acute phase; nevertheless, renal involvement in the post-infection period has recently been emphasized. The present review aims to evaluate the growing literature on kidney involvement in the SARS-CoV-2 infection along with clinical features reported both in the acute phase of the infection and in the post-acute COVID-19 period by assessing potential pathophysiological frameworks explaining such conditions. Chronic kidney disease and development of acute kidney injury (AKI) in the course of initial hospitalization are associated with high mortality and morbidity rates. Moreover, growing evidence suggests a decline in renal function in the 6-to-12-month follow-up period even in patients without any signs of AKI during the acute phase. Despite such concerns there are no guidelines regulating the follow-up period or therapeutic alternatives for such patient population. In conclusion, the burden of COVID-19 on the kidney is yet to be determined. Future prospective large scale studies are needed with long follow-up periods assessing kidney involvement via multiple parameters such as biopsy studies, urinalysis, measurement of serum creatinine and cystatin C, directly measured glomerular filtration rate, and assessment of tubular function via urinary β²-microglobulin measurements. Graphical abstract