Richard Amerling

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.

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 2-3 l 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.

Clinical experience with continuous flow and flow-through peritoneal dialysis.

Concern over the inherent inefficiency of solute removal by conventional peritoneal dialysis (PD) has led to renewed interest in continuous flow PD (CFPD). We present clinical data from two experiences with CFPD. In the first, two catheters were used to recirculate a fixed intraperitoneal volume through an external circuit comprised of a standard hemodialysis system. The second patient had a dual‐lumen PD catheter and was studied during two sessions of flow‐through PD (FTPD) using sterile PD solution. Urea clearances with both techniques were around 30 ml/min, which is consistent with data reported in the literature. Significant streaming of dialysate from port to port within the peritoneal cavity limited clearances. CFPD offers a potentially safe and effective alternative to daily or nightly home hemodialysis.

Interventional Nephrology and Dialysis: Continuous Flow Peritoneal Dialysis: Principles and Applications

Continuous flow peritoneal dialysis (CFPD) is a technique of renal replacement therapy (RRT) dating back to the 1960s. Its essential features are a fixed intraperitoneal volume and rapid, continuous movement of dialysis solution into and out of the peritoneal cavity. Inlet and outlet catheters and a means of generating a large volume of sterile dialysate are required. External regeneration of dialysate via conventional hemodialysis (HD) equipment or sorbent technology mitigates the need for large volumes of sterile fluid and makes the technique feasible. Clearance depends on the peritoneal mass transfer coefficient, rate of dialysate flow, and efficiency of external regeneration. Studies to date all demonstrate small solute clearances three to eight times greater than conventional automated peritoneal dialysis (PD). Catheter design is crucial to the clinical success of the technique and will be discussed. Potential applications include daily home dialysis, treatment of acute renal failure in the intensive care unit (ICU), and ultrafiltration of ascites. Clinical experience with the latter will be presented in detail.

Advances in Peritoneal Dialysis in Acute Kidney Injury

Peritoneal dialysis (PD) is a simple, safe, cheap, and efficient renal replacement therapy method. It can correct metabolic disorders and fluid overload in acute kidney injury (AKI) patients both in and out of the intensive care unit. Use of PD in AKI is enhanced by placement of a Tenckhoff catheter, which can be safely accomplished at the bedside. Some PD modalities, such as high-volume PD and continuous-flow PD, can provide dialysis doses and efficiency comparable to extracorporeal blood purification methods. PD is particularly suitable for neonates, children, and patients with refractory heart failure or who are otherwise hemodynamically unstable. PD should be considered in situations where systemic anticoagulation and/or vascular access are problematic. PD is limited by a lower efficiency that may produce inadequate renal replacement in larger and/or severely hypercatabolic patients. Fluid removal can be unpredictable, there is a risk of infection, and possible issues with mechanical ventilation. In this article, we discuss the use of PD in AKI, with emphasis on recent advances.

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.

The 2006 K/DOQI Guidelines for Peritoneal Dialysis Adequacy Are Not Adequate

The 2006 National Kidney Foundation K/DOQI guidelines have lowered the peritoneal dialysis adequacy standard of Kt/Vurea from 2.1 to 1.7 in anuric patients, largely based on the patient survival results of 2 clinical trials in Mexico and Hong Kong. It is our contention that the guidelines may be misleading since they have chosen to ignore the bias in these trials and have ignored the adverse outcomes in control groups in the trials on which the guidelines are based, as well as the body size of the subjects in these trials. Body size has changed in the US and Canada over the last few decades and there are similar changes worldwide. We suggest that the minimum targets for peritoneal dialysis be reinstituted at the previous standard Kt/Vurea of 2.0.

The Potential Application of Sorbents in Peritoneal Dialysis

Sorbents have been designed to remove small and middle molecular weight toxins, including low molecular weight proteins, peptides, cytokines and chemokines in patients undergoing renal replacement therapy. Sorbents assist the process of peritoneal dialysate regeneration and have the potential to improve the efficiency of continuous flow peritoneal dialysis.

Validation of the Blood Temperature Monitor for Extracorporeal Thermal Energy Balance during in vitro Continuous Hemodialysis

Continuous renal replacement therapies (CRRT) are today considered a well-tolerated and efficient group of treatments for acute renal failure in critically ill patients [1–12]. The evolution in technology of CRRT has only partially followed the more sophisticated evolution that took place in the equipment for chronic hemodialysis patients. In such patients, the increased morbidity and the progressively increased age, require a gentle and carefully monitored hemodialysis therapy. To achieve such results, on-line monitoring techniques have been developed including urea sensors, temperature sensors, blood volume sensors and biofeedback systems [13]. We will try to analyze how this new technology could have a positive impact in acute patients and how it could be implemented in the present equipment for CRRT [14–16].

Con: On cardiovascular outcomes and the arteriovenous fistula: lesser of evils

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