How to improve dialysis adequacy in patients with vascular access problems

Blood flow rate is a critical factor in the achievement of an adequate dialysis dose. The aim of this review is to evaluate the possibility of optimizing dialysis dose in terms of Kt/V in patients with reduced vascular access (VA) flow rate, considering effective blood flow (Qb eff), recirculation, access flow and hemodialyzer. In patients where the achievement of adequate blood flow rates are difficult to obtain and no surgical revision is necessary, to avoid under dialysis the increase in the treatment time should be the first choice solution. If such a solution is difficult for various reasons, a forced partial blood flow recirculation, especially in central venous catheters (CVCs) with reversed lines can be useful, on condition that the dialysis session is prolonged. The possibility of increasing the efficiency of dialysis through an increase in filter clearance has to be considered. Monitoring arterial pre-pump pressure (P asp) and optimizing ratio P asp/Qb eff during hemodialysis (HD) is one possible solution to improve blood flow rates, but it is necessary to educate and involve the staff. Recent developments in a new class of highly effective hemodialyzer due to dialysate distribution, has opened up interesting opportunities in terms of dialysis adequacy in patients with reduced VA flow rate.     

Early failure rates of arterovenous fistulas for hemodialysis: evaluation of six-year activity

Maintenance and complications of vascular access (VA) for hemodialysis (HD) represent the leading cause of morbidity and health care cost among end stage renal disease population. To define the reasons for the use of a particular VA at the beginning of replacement treatment, we prospectively evaluated the early failure rate and survival of arterovenous fistula (AVF) in 183 patients. These patients had high prevalence of cardiovascular risk factors and co-morbid conditions, and began HD in our renal unit from the 1st of January 1995. As a part of this study the present analysis focuses on potential predictors of early failure of the first AVF (within the first 7 days after the operation). Overall, 279 AVF were prepared: 193 at the wrist and 86 at the upper arm, including 11 prosthetic grafts; 150 patients (82%) were given a distal AVF in the first operation. Our conservative policy resulted in a relatively high prevalence of native AVF in use among our prevalent HD patients (84.3%). Early failure of the first VA was 10.4%. Multivariate analysis showed that this event was neither significantly associated with all traditional risk factors and co-morbids tested, nor with the operating surgeon. We conclude that in this prospectively studied cohort, the high rate of native AVF created in order to preserve the vascular bed, though associated with a high early failure rate unaffected by traditional cardiovascular risk factors, resulted in a low proportion of permanent catheters and arterovenous grafts in use among prevalent HD patients. (The Journal of Vascular Access 2001; 2: 154-160).     

Factors influencing permanent catheter performance

Permanent dual lumen catheters (PDLC) provide an alternative vascular access in patients considered unsuitable for arteriovenous fistula, graft or peritoneal dialysis. However, the use of PDLC is often complicated by inadequate blood flow. The aim of this study was to identify catheter dysfunctions. We studied prospec-tively 57 chronic hemodialyzed patients, 73+/-11 years of age, with PDLC for 18+/-14 (1-48) months. Catheters were tunneled in silicone (MedComp Tesio n= 40) or in polyurethane (Permcath Quinton n = 11, GamCath Gambro n = 6) in left or right internal jugular (n = 49), in left or right subclavian (n = 3) and in right femoral vein (n = 5). We studied the blood viscosity indices (hematocrit, total protein, cholesterol and triglycerides), catheter intra-dialytic parameters (pre-pump and venous pressure), localization of the catheter tip (superior vena cava = SVC, right atrium = RA, inferior vena cava = IVC), blood pressure before and after hemodialysis during the 3 last dialyses, use of anticoagulant (ACT) or antiaggregant therapy (AAT) and previous infectious episodes. The mean blood flow was 269+/-37 ml/min (median 280 ml/min). The patients were divided according to the median value into groups I (Qb < 280, n = 28) and group II (Qb > 280, n =29). Results: Blood viscosity, patients' mean arterial pressure and venous catheter line pressure did not differ between the two groups. Pre-pump pressure, at the start and at the end of treatment, was higher in group I. ACT, AAT and previous infectious episodes could not explain the low-performance. Blood flows of catheters localized in RA, SVC, and in IVC were respectively 287+/-20, 268+/-39, 244+/-27 ml/min. In the first case the Qb was significantly higher than IVC (p = 0.03) and SVC (p = 0.04). In conclusion, the most important factor influencing blood flow rates seems to be the position of the catheter tip in the venous system. The best blood flows were found in catheters with the tip localized in the right cardiac cavities, while PLDC placed in inferior vena cava showed lower blood flow.     

Lifetime risk of ESRD

Lifetime risk is the cumulative risk of experiencing an outcome between a disease-free index age and death. The lifetime risk of ESRD for a middle-aged individual is a relevant and easy to communicate measure of disease burden. We estimated lifetime risk of ESRD in a cohort of 2,895,521 adults without ESRD from 1997 to 2008. To estimate lifetime risk of ESRD by level of baseline kidney function, we analyzed a cohort of participants who had a serum creatinine measurement. We also estimated the sex- and index age-specific lifetime risk of incident ESRD and accounted for the competing risk of death. Among those individuals without ESRD at age 40 years, the lifetime risk of ESRD was 2.66% for men and 1.76% for women. The risk was higher in persons with reduced kidney function: for eGFR=44-59 ml/min per 1.73 m(2), the lifetime risk of ESRD was 7.51% for men and 3.21% for women, whereas men and women with relatively preserved kidney function (eGFR=60-89 ml/min per 1.73 m(2)) had lifetime risks of ESRD of 1.01% and 0.63%, respectively. The lifetime risk of ESRD was consistently higher for men at all ages and eGFR strata compared with women. In conclusion, approximately 1 in 40 men and 1 in 60 women of middle age will develop ESRD during their lifetimes (living into their 90s). These population-based estimates may assist individuals who make decisions regarding public health policy.     

Regulatory T cells and minimal change nephropathy: in the midst of a complex network

Minimal change nephrosis (MCN) is an important cause of morbidity in children. In spite of successful therapies having been developed in the last three decades, most aspects related to pathogenesis still remain poorly defined. Evolution in basic immunology and results deriving from animal models of the disease suggest a complex interaction of factors and cells starting from activation of innate immunity and continuing with antigen presentation. Oxidants, CD80 and CD40/CD40L have probably a relevant role at the start. Studies in animal models and in human beings also suggest the possibility that the same molecules (i.e. CD80, CD40) are expressed by podocytes under inflammatory stimuli, representing a direct potential mechanism for proteinuria. B and T cells could play a relevant role this contest. Implication of B cells is suggested indirectly by studies utilizing anti‐CD20 monoclonal antibodies as the main therapy. The role of regulatory T cells (T_regs) is supported mainly by results in animal models of nephrotic syndrome (i.e. adriamycin, puromycin, lipopolysaccharide), showing a protective effect of direct T_reg infusion or stimulation by interleukin 2 (IL‐2). Limited studies have also shown reduced amounts of circulating T_regs in patients with active MCN cells. The route from bench to bedside would be reduced if results from animal models were confirmed in human pathology. The expansion of T_regs with recombinant IL‐2 and new anti‐CD20 monoclonal antibodies is the beginning. Blocking antigen‐presenting cells with cytotoxic T lymphocyte antigen (CTLA‐4)–Ig fusion molecules inhibiting CD80 and/or with blockers of CD40–CD40 ligand interaction represent potential new approaches. The hope is that evolution in therapies of MCN could fill a gap lasting 30 years.     

Phytoestrogen‐Rich Natural Preparation for Treatment of Climacteric Syndrome and Atherosclerosis Prevention in Perimenopausal Women

The present study evaluated the risks and benefits of phytoestrogen treatment in healthy perimenopausal women in relation to the dynamics of climacteric syndrome and progression of atherosclerosis. Study participants were treated with placebo or phytoestrogen‐rich natural preparation Karinat based on grape (Vitis vinifera) seeds, green tea (Camellia sinensis) leaves, hop (Hunulus lupulus) cone powder and garlic (Allium sativum) powder. The dynamics of climacteric syndrome was evaluated by Kupperman Index and Utian Quality of Life Scale. Atherosclerosis progression was evaluated by measuring carotid intima‐media thickness. Significant changes of climacteric syndrome's severity in both Karinat and placebo groups (p = 0.005 and p = 0.001) were obtained after 24 months of follow‐up. Detailed analysis of Kupperman Index suggested that Karinat possessed a significant effect on nervousness (p = 0.010), weakness (p = 0.020) and formication (p = 0.010). A significant improvement of medical (p = 0.070) and emotional (p = 0.060) components of Kupperman Index and Utian Quality of Life Scale was also observed in Karinat group. However, difference in carotid intima‐media thickness between the two groups was not statistically significant at follow‐up. A slight positive effect of phytoestrogens on climacteric syndrome manifestations was demonstrated in this study. Karinat can be used for alleviation of climacteric syndrome and cardiovascular disease prevention in perimenopausal women. Copyright © 2017 John Wiley & Sons, Ltd.