Sympathetic Activation and Baroreflex Function during Intradialytic Hypertensive Episodes

BACKGROUND: The mechanisms of intradialytic increases in blood pressure are not well defined. The present study was undertaken to assess the role of autonomic nervous system activation during intradialytic hypertensive episodes. METHODOLOGY/PRINCIPAL FINDINGS: Continuous interbeat intervals (IBI) and systolic blood pressure (SBP) were monitored during hemodialysis in 108 chronic patients. Intradialytic hypertensive episodes defined as a period of at least 10 mmHg increase in SBP between the beginning and the end of a dialysis session or hypertension resistant to ultrafiltration occurring during or immediately after the dialysis procedure, were detected in 62 out of 113 hemodialysis sessions. SBP variability, IBI variability and baroreceptor sensitivity (BRS) in the low (LF) and high (HF) frequency ranges were assessed using the complex demodulation technique (CDM). Intradialytic hypertensive episodes were associated with an increased (n = 45) or decreased (n = 17) heart rate. The maximal blood pressure was similar in both groups. In patients with increased heart rate the increase in blood pressure was associated with marked increases in SBP and IBI variability, with suppressed BRS indices and enhanced sympatho-vagal balance. In contrast, in those with decreased heart rate, there were no significant changes in the above parameters. End-of-dialysis blood pressure in all sessions associated with hypertensive episode was significantly higher than in those without such episodes. In logistic regression analysis, predialysis BRS in the low frequency range was found to be the main predictor of intradialytic hypertension. CONCLUSION/SIGNIFICANCE: Our data point to sympathetic overactivity with feed-forward blood pressure enhancement as an important mechanism of intradialytic hypertension in a significant proportion of patients. The triggers of increased sympathetic activity during hemodialysis remain to be determined. Intradialytic hypertensive episodes are associated with higher end-of-dialysis blood pressure, suggesting that intradialytic hypertension may play a role in generation of interdialytic hypertension

CKD-MBD after kidney transplantation

Successful kidney transplantation corrects many of the metabolic abnormalities associated with chronic kidney disease (CKD); however, skeletal and cardiovascular morbidity remain prevalent in pediatric kidney transplant recipients and current recommendations from the Kidney Disease Improving Global Outcomes (KDIGO) working group suggest that bone disease—including turnover, mineralization, volume, linear growth, and strength—as well as cardiovascular disease be evaluated in all patients with CKD. Although few studies have examined bone histology after renal transplantation, current data suggest that bone turnover and mineralization are altered in the majority of patients and that biochemical parameters are poor predictors of bone histology in this population. Dual energy X-ray absorptiometry (DXA) scanning, although widely performed, has significant limitations in the pediatric transplant population and values have not been shown to correlate with fracture risk; thus, DXA is not recommended as a tool for the assessment of bone density. Newer imaging techniques, including computed tomography (quantitative CT (QCT), peripheral QCT (pQCT), high resolution pQCT (HR-pQCT) and magnetic resonance imaging (MRI)), which provide volumetric assessments of bone density and are able to discriminate bone microarchitecture, show promise in the assessment of bone strength; however, future studies are needed to define the value of these techniques in the diagnosis and treatment of renal osteodystrophy in pediatric renal transplant recipients

Continuous flow peritoneal dialysis: Current state-of-the-art and obstacles to further development

Peritoneal dialysis (PD) is still underutilized as home based renal replacement therapy and in-patient treatment of acute renal failure. Hindering the expansion of PD is poor solute clearance, which is a result of the intermittent dwell technique. Continuous flow PD is an old concept that has demonstrated urea clearances from 2-5 times higher than standard PD. It relies on a 2-31 dwell volume and continuous dialysate flow at 100-300 ml/min. This high flow rate dictates the need for an efficient dual lumen catheter, or two separate catheters with ports separated maximally, as well as a means to generate or regenerate large volumes of fluid. A modified hemodialysis system can easily be adapted to regenerate sterile peritoneal dialysate, and a dual lumen catheter with excellent flow characteristics has been designed. Ultrafiltration control and a means to accurately balance transperitoneal with external ultrafiltration persist as technical challenges. Continuous flow PD remains an attractive modality for daily home dialysis and treatment of acute renal failure. Copyright (c) 2006 S. Karger AG, Basel

Arteriovenous Fistula Toxicity

The arteriovenous fistula (AVF) has been a mainstay of hemodialysis treatments and the preferred access route since its inception in the 1960s, due to its longevity and resistance to infection. However, the AVF is not benign. There is significant primary failure, as well as cardiac, vascular, and other, less well recognized, complications. Together, they represent toxicity, to which considerable morbidity and mortality can be attached. Official policy, based on guidelines where AVF toxicity is given short shrift, drives an increase in use of these devices, and may have undesired consequences. Copyright (C) 2011 S. Karger AG, Base

Guidelines have done more harm than good

Practice guidelines have proliferated in medicine but their impact on actual practice and outcomes is difficult, if not impossible, to quantify. Though guidelines are based largely on observational data and expert opinion, it is widely believed that adherence to them leads to improved outcomes. Data to support this belief simply does not exist. If guidelines are universally ignored, their impact on treatment and outcomes is minimal. The incorporation of guidelines into treatment protocols and performance measures, as is now common practice in nephrology, increases greatly the likelihood that guidelines will influence practice and hence, outcomes. Practice patterns set up this way may be resistant to change, should new evidence emerge that contradicts certain recommendations. Even if guidelines are entirely appropriate, a 'one-size-fits-all' approach is likely to benefit some, but not all. Certain patients may be harmed by adherence to specific guidelines. Guidelines certainly do not encourage clinicians to consider and treat each patient as an individual. They are unlikely to stimulate original research. They are created by a process that is artificial, laborious and cumbersome. This all but guarantees many guidelines are obsolete by the time they are published. Guidelines are produced with industry support and recommendations often have a major impact on sales of industry products. Copyright (c) 2008 S. Karger AG, Basel

Guidelines for guidelines

Practice guidelines are proliferating in medicine. In addition to methodological problems that cause guidelines to be outdated rapidly, they are plagued by conflicts of interest. They are largely consensus opinions of panels of experts, most of whom are supported by industry. Professional societies, health insurers, Centers for Medicare and Medicaide Services, and dialysis providers also benefit from guidelines. Little attention is paid to the potential for harm to patients, and to the profession of medicine, from the widespread use of guidelines. Copyright (c) 2007 S. Karger AG, Basel