Dialyzer and machine technologies: application of recent advances to clinical practice

Market Consolidation and Innovation in US Dialysis

While patients with end-stage kidney disease have benefited from innovations in clinical therapeutics and care delivery, these changes have been primarily incremental and have not fundamentally transformed care delivery. Dialysis markets are highly concentrated, which may impede innovation. Unique features of the dialysis industry that have contributed to consolidation can help to explain links between consolidation and innovation. We discuss these unique features and then provide a framework for considering the effects of consolidation on innovation in dialysis that focuses on the following economic considerations: (1) industry characteristics, composition, and stage of consolidation, (2) innovation characteristics and relative profitability, (3) the role of government regulation, and (4) innovation from smaller providers and new entrants. We present examples of how these considerations have influenced the adoption of alternative dialysis technologies such as peritoneal dialysis and erythropoietin-stimulating agents, and we discuss how consolidated markets can both help and hinder recent policy initiatives to transform dialysis care delivery. Only by considering these important drivers of consolidation, future efforts can be successful in transforming end-stage kidney disease care.

Less Complexity in Hemodialysis Machines Reduces Time and Physical Load for Operator Actions

Purpose

Innovative hemodialysis systems are designed to ensure user safety and reduce operational time to allow health-care personnel to focus on patient care. The 6008 CareSystem has been developed to simplify the extracorporeal circuit of the system through a disposable cassette, automate operation steps, and facilitate handling in comparison to its predecessor - the 5008 CorDiax. The present investigations were performed with the aim of evaluating usability, safety, and ergonomic aspects of the new therapy system.

Methods

A time-motion study compared these two hemodialysis systems with video and time recording of handling steps required to prepare, operate, and dismantle a dialysis machine. The ergonomic burden on hands and finger joints was evaluated in a second study, again by video-recording the simulated operation of both dialysis systems.

Results

The number of handling steps required for the 6008 CareSystem and critical contact points were reduced by 26% in comparison to the 5008 CorDiax for patients with arteriovenous fistula used for vascular access and by 22% for those with a catheter used for vascular access. Total process time was reduced by 2.83 and 2.57 minutes using fistulae and catheters for vascular access, respectively. The number of hand grips and finger and thumb presses was reduced by approximately 50% and required less strength to execute.

Conclusion

The most recent hemodialysis system confirmed its ease of use and user safety through fewer handling steps and less physical burden on the user. Shorter operational time should enable more patient-focused care.

Drug Dosing in Critically Ill Patients with Acute Kidney Injury and on Renal Replacement Therapy

Acute kidney injury (AKI) complicates in around 40-50% of patients in intensive care units (ICUs), and this can account for up to 80% mortality, especially in those patients requiring renal replacement therapy (RRT). Appropriate drug dosing in such patients is a challenge to the intensivists due to various factors such as patient related (appropriate body weight, organ clearance, serum protein concentration), drug related [molecular weight (MW), protein binding, volume of distribution (V _d), hydrophilicity, or hydrophobicity], and RRT related (type, modality of solute removal, filter characteristics, dose, and duration). Therapeutic drug monitoring (TDM) of drugs can be a promising solution to this complex scenario to titrate a drug to its clinical response, but it is available only for a few drugs. In this review, we discussed drug dosing aspects of antimicrobials, sedatives, and antiepileptics in critically ill patients with AKI on RRT.

How to cite this article

Saran S, Rao NS, Azim A. Drug Dosing in Critically Ill Patients with Acute Kidney Injury and on Renal Replacement Therapy. Indian J Crit Care Med 2020;24(Suppl 3):S129-S134.

Volume Management by Renal Replacement Therapy in Acute Kidney Injury

Management of fluid balance is one of the basic but vital tasks in the care of critically ill patients. Hypovolemia results in a decrease in cardiac output and tissue perfusion and may lead to progressive multiple organ dysfunction, including the development of acute renal injury (AKI). However, in an effort to reverse pre-renal oliguria, it is not uncommon for patients with established oliguric acute renal failure, particularly when associated with sepsis, to receive excessive fluid resuscitation, leading to fluid overload. In patients with established oliguria, renal replacement therapy may be required to treat hypervolemia. Safe prescription of fluid loss during RRT requires intimate knowledge of the patient's underlying condition, understanding of the process of ultrafiltration and close monitoring of the patient's cardiovascular response to fluid removal. To preserve tissue perfusion in patients with AKI, it is important that RRT be prescribed in a way that optimizes fluid balance by removing fluid without compromising the effective circulating fluid volume. In patients who are clinically fluid overloaded, it is equally important that the amount of fluid removed be as exact as possible. Fluid balance errors can occur as a result of inappropriate prescription, operator error or machine error. Some CRRT machines have potential for significant fluid errors if alarms can be overridden. Threshold values for fluid balance error have been developed which can be used to predict the severity of harm. It is important that RRT education programs emphasize the risk associated with fluid balance errors and with overriding machine alarms.

Three-Dimensional Dialysate flow Analysis in a Hollow-Fiber Dialyzer by Perfusion Computed Tomography

Perfusion computed tomography (PCT) is a means to rapidly and easily evaluate cerebral perfusion in patients presenting with acute stroke symptoms, which provides insights into capillary-level hemodynamics. In this study, we used PCT to analyze the 3-dimensional dialysate flow in a low-flux hemodialyzer equipped with a standard fiber bundle. The dynamic CT studies were performed with 64-channel multi-detector row CT (MDCT) at a dialysate flow rate of 500 ml/min and a 1.0 ml/sec injection rate of contrast agent. Central volume principle was used to calculate hydrodynamic parameters by deconvolution of time-density curves (TDCs). Functional maps of dialysate flow (DF), dialysate volume (DV), and mean transit time (MTT) could quantitatively describe the dialysate flow maldistribution, variations in fiber packing, and perfusion pressure distribution in a hemodialyzer, respectively. PCT by means of analysis was able to overcome the limitations of conventional imaging techniques for analyzing dialysate flow distributions in hollow-fiber dialyzers. Not only local hydrodynamic phenomena at microscopic level but also macroscopic flow behavior of dialysate were visualized quantitatively. Therefore, we concluded that PCT is a quantitative analysis method to provide better insights into hydrodynamics of hollow-fiber dialyzers and is expected to contribute to optimization of artificial kidneys.

Nomenclature for renal replacement therapy and blood purification techniques in critically ill patients: practical applications

This article reports the conclusions of the second part of a consensus expert conference on the nomenclature of renal replacement therapy (RRT) techniques currently utilized to manage acute kidney injury and other organ dysfunction syndromes in critically ill patients. A multidisciplinary approach was taken to achieve harmonization of definitions, components, techniques, and operations of the extracorporeal therapies. The article describes the RRT techniques in detail with the relevant technology, procedures, and phases of treatment and key aspects of volume management/fluid balance in critically ill patients. In addition, the article describes recent developments in other extracorporeal therapies, including therapeutic plasma exchange, multiple organ support therapy, liver support, lung support, and blood purification in sepsis. This is a consensus report on nomenclature harmonization in extracorporeal blood purification therapies, such as hemofiltration, plasma exchange, multiple organ support therapies, and blood purification in sepsis.

International differences in hemodialysis delivery and their influence on outcomes

There are many variations in the delivery of hemodialysis. These variations include components of conventional dialysis, such as membrane type, dialysis dose, and session duration. In addition, alternative approaches to dialysis, such as hemodiafiltration, nocturnal hemodialysis, and short daily hemodialysis, also may be considered. For some of these practice variations, data exist to support one approach over another (eg, fistulas rather than grafts and catheters), but for many, no such data exist. Very few practice variations have been examined in randomized trials, and we are reliant predominantly on observational data. This review examines some practice variations in hemodialysis delivery, attempting to highlight which of these may be appropriate to consider when optimizing dialysis delivery in the clinic.

In vitro utilization of ferromagnetic nanoparticles in hemodialysis therapy

The in vitro utilization of biocompatible ferromagnetic nanoparticles (BFNs) in hemodialysis (HD), routinely used today for the treatment of end stage renal disease (ESRD), is introduced in this work. The proposed strategy is termed magnetically assisted hemodialysis (MAHD) and it aims to become a more efficient development of conventional HD. The method is based on the production of biocompatible ferromagnetic nanoparticles-targeted binding substances conjugates (BFNs-TBSs Cs) constructed of BFNs and specifically designed TBSs that should have high affinity and binding capacity for target toxic substances (TTSs) which must be removed from the ESRD patient subjected to HD. Antibodies or even specific proteins could serve as the TBS of the desired BFNs-TBSs Cs. The BFNs-TBSs Cs should be administered to the patient timely prior to the MAHD session so as to bind with the desired TTSs during their free circulation in the vascular network. Eventually, the complete BFNs-TBSs-TTSs structure can be selectively removed during the MAHD session by means of an external inhomogeneous magnetic field that is applied either at the dialyzer or at other collection point(s) along the blood circulation line of the dialysis machine. The advantages of MAHD over conventional HD regarding the patient's comfort and overall health status are discussed in detail among practical issues. To examine this proposition we employed Fe(3)O(4) and bovine serum albumin (BSA) as the BFN and the TBS constituents respectively, since they are both highly biocompatible. By means of x-ray diffraction, atomic force microscopy, circular dichroism spectropolarimetry, UV-vis spectrophotometry, SQUID magnetometry, and nuclear magnetic resonance we evaluated (i) the structural/morphological characteristics, (ii) the magnetic retraction efficiency, and most importantly (iii) the toxin binding affinity and capacity of both bare Fe(3)O(4) BFNs and Fe(3)O(4)-BSA Cs by performing in vitro experiments on specific TTSs. Homocysteine and p-cresol were chosen as representative TTSs and were investigated in great detail. The results obtained prove the in vitro applicability of the proposed MAHD method. Corrections were made to this article on 6 November 2007 (see figure 10 caption and lines 10 and 11 of page 11). The corrected electronic version is identical to the print version.