Standard Intermittent Hemodialysis Research Articles

Choosing a CRRT machine and modality.

Expanded use and steady improvements in continuous renal replacement techniques (CRRT) have enhanced the safety of the application of kidney replacement therapy (KRT) to hemodynamically unstable intensive care unit (ICU) patients. The longer duration of therapy and the personalized prescription provided by continuous therapies are associated with greater hemodynamic stability and a modestly higher likelihood of kidney recovery than standard intermittent hemodialysis (IHD). Studies designed to evaluate the effect on mortality over intermittent therapies lack evidence of benefit. A lack of standardization and considerable variation in how CRRT is performed leads to wide variation in how the technique is prescribed, delivered, and optimized. Technology has progressed in critical care nephrology, and more progress is coming. New CRRT machines are equipped with a friendly user interface that allows easy performance and monitoring, permitting outcome measurements and improved patient quality control. This review discusses the key concepts necessary to guide nephrologists to prescribe and deliver KRT to critically ill ICU patients.

An evaluation of four modes of low-dose anticoagulation during intermittent haemodialysis

IntroductionIntensive care participants that need dialysis frequently suffer from increased risk of bleeding. Standard intermittent haemodialysis (SHD) includes anticoagulation to avoid clotting of the dialysis system. The aim of this study was to clarify which of four different low-dose anticoagulant modes was preferable in reducing the exposure to i.v. unfractionated heparin (heparin) and maintaining patency of the dialysis circuit.MethodsTwenty-three patients on SHD were included to perform haemodialysis with four modes of low-dose anticoagulation. For comparative analyses, patients served as their own control. Haemodialysis with a single bolus of tinzaparin at the start was compared to haemodialysis initiated without i.v. heparin but priming with (1) heparin in saline (H), (2) heparin and albumin in saline (HA), (3) heparin and albumin in combination with a citrate-containing dialysate (HAC), (4) saline and usinga heparin-coated filters (Evodial®). The priming fluid was discarded before dialysis started. Blood samples were collected at 0, 30 and 180 min during haemodialysis. Smaller bolus doses of heparin (500 Units/dose) were allowed during the modes to avoid interruption by clotting.FindingsThe mean activated partial thromboplastin (APTT) time as well as the doses of anticoagulation administered was highest with SHD and least with HAC and Evodial®. Mode H versus SHD had the highest rate of prematurely interrupted dialyses (33%, p = 0.008). The urea reduction rate was less with Evodial® vs. SHD (p < 0.01). One hypersensitivity reaction occurred with Evodial®. Changes in blood cell concentrations and triglycerides differed between the modes.DiscussionIf intermittent haemodialysis is necessary in patients at risk of bleeding, anticoagulation using HAC and Evodial® appeared most preferable with least administration of heparin, lowest APTT increase and lowest risk for prematurely clotted dialyzers in contrast to the least plausible H mode.

Extracorporeal CO2 removal by hemodialysis: in vitro model and feasibility

BackgroundCritically ill patients with acute respiratory distress syndrome and acute exacerbations of chronic obstructive pulmonary disease often develop hypercapnia and require mechanical ventilation. Extracorporeal carbon dioxide removal can manage hypercarbia by removing carbon dioxide directly from the bloodstream. Respiratory hemodialysis uses traditional hemodialysis to remove CO2 from the blood, mainly as bicarbonate. In this study, Stewart’s approach to acid-base chemistry was used to create a dialysate that would maintain blood pH while removing CO2 as well as determine the blood and dialysate flow rates necessary to remove clinically relevant CO2 volumes.MethodsBench studies were performed using a scaled down respiratory hemodialyzer in bovine or porcine blood. The scaling factor for the bench top experiments was 22.5. In vitro dialysate flow rates ranged from 2.2 to 24 mL/min (49.5–540 mL/min scaled up) and blood flow rates were set at 11 and 18.7 mL/min (248–421 mL/min scaled up). Blood inlet CO2 concentrations were set at 50 and 100 mmHg.ResultsResults are reported as scaled up values. The CO2 removal rate was highest at intermittent hemodialysis blood and dialysate flow rates. At an inlet pCO2 of 50 mmHg, the CO2 removal rate increased from 62.6 ± 4.8 to 77.7 ± 3 mL/min when the blood flow rate increased from 248 to 421 mL/min. At an inlet pCO2 of 100 mmHg, the device was able to remove up to 117.8 ± 3.8 mL/min of CO2. None of the test conditions caused the blood pH to decrease, and increases were ≤0.08.ConclusionsWhen the bench top data is scaled up, the system removes a therapeutic amount of CO2 standard intermittent hemodialysis flow rates. The zero bicarbonate dialysate did not cause acidosis in the post-dialyzer blood. These results demonstrate that, with further development, respiratory hemodialysis can be a minimally invasive extracorporeal carbon dioxide removal treatment option.

Continuous Dialysis Therapies: Core Curriculum 2016.

Over the past 2 decades, the development of new renal replacement therapy (RRT) techniques, including continuous RRT (CRRT), has allowed the therapy to be offered to sicker and hemodynamically unstable patients in the intensive care unit (ICU) setting. However, studies designed to compare continuous versus intermittent therapies have not shown a beneficial effect on mortality. Several inherent characteristics of CRRT, including the longer duration of therapy, have been associated with greater hemodynamic stability and a higher likelihood of kidney recovery compared to standard intermittent hemodialysis (IHD). There still exists considerable variation in the application of CRRT in the ICU due to a lack of standardization in this field. To some extent, this reflects the lack of consensus on several aspects of RRT (eg, timing of initiation, dose, session length, and standards for monitoring). Additionally, there is wide variation in how the techniques are prescribed, delivered, and optimized to improve patient outcomes. In this Core Curriculum, we focus on the key concepts to guide nephrologists to prescribe and deliver CRRT and utilize its therapeutic potential. CRRT PRINCIPLES The term CRRT describes blood purification techniquesthatharnesstheinherentprinciplesofsupportof kidney function for achieving solute and fluid homeostasis continuously and are intended to be applied for 24 hours or longer. As with other dialysis techniques, CRRT requires a well-functioning access, a permeable membrane, pumps to circulate blood and various solutions across the membrane with accurate fluid balancing, and pressure monitoring systems. Anticoagulation is generally required to achieve a functional circuit over an extended period. Although the basic components of CRRT are similar to those of IHD, there are significant differences in how these are used to achieve solute and fluid homeostasis. Several techniques are grouped in CRRT and are distinguished by different mechanisms of solute transport, fluid management, type of membrane, and use of dialysate and substitution solution.

A regenerable potassium and phosphate sorbent system to enhance dialysis efficacy and device portability: a study in awake goats.

Patients on standard intermittent haemodialysis suffer from strong fluctuations in plasma potassium and phosphate. Prolonged dialysis with a wearable device, based on continuous regeneration of a small volume of dialysate using ion exchangers, could moderate these fluctuations and offer increased clearance of these electrolytes. We report in vivo results on the efficacy of potassium and phosphate adsorption from a wearable dialysis device. We explore whether equilibration of ion exchangers at physiological Ca 2+ , Mg 2+ and hypotonic NaCl can prevent calcium/magnesium adsorption and net sodium release, respectively. Effects on pH and HCO3- were studied. Healthy goats were instrumented with a central venous catheter and dialysed. Potassium and phosphate were infused to achieve plasma concentrations commonly observed in dialysis patients. An adsorption cartridge containing 80 g sodium poly(styrene-divinylbenzene) sulphonate and 40 g iron oxide hydroxide beads for potassium and phosphate removal, respectively, was incorporated in a dialysate circuit. Sorbents were equilibrated and regenerated with a solution containing NaCl, CaCl 2 and MgCl 2 . Blood was pumped over a dialyser and dialysate was recirculated over the adsorption cartridge in a countercurrent direction. Potassium and phosphate adsorption was 7.7 ± 2.7 and 4.9 ± 1.3 mmol in 3 h, respectively. Adsorption capacity remained constant during consecutive dialysis sessions and increased with increasing K + and PO43-. Equilibration at physiological Ca 2+ and Mg 2+ prevented net adsorption, eliminating the need for post-cartridge calcium and magnesium infusion. Equilibration at hypotonic NaCl prevented net sodium release Fe 2+ and arterial pH did not change. Bicarbonate was adsorbed, which could be prevented by equilibrating at HCO3- 15 mM. We demonstrate clinically relevant, concentration-dependent, pH-neutral potassium and phosphate removal in vivo with small volumes of regenerable ion exchangers in our prototype wearable dialysis device. Application of the selected ion exchangers for potassium and phosphate removal in a wearable dialysis device appears to be effective with a low-risk profile.

Intermittent high-volume predilution on-line haemofiltration versus standard intermittent haemodialysis in critically ill patients with acute kidney injury: a prospective randomized study

The optimal modality of dialysis treatment in critically ill patients with acute kidney injury (AKI) remains unclear. Intermittent high-volume predilution on-line haemofiltration (HF) is not a well-established dialysis modality. The purpose of the study was to compare clinical outcomes between HF and standard intermittent haemodialysis (HD) in this specific population. In this prospective, randomized, controlled single-centre clinical study, we compared mortality and recovery of kidney function between HF and HD in critically ill adult patients with AKI. The primary study outcome was 60-day all-cause mortality. Secondary study outcomes included 30-day and in-hospital all-cause mortality along with recovery of kidney function. Time to kidney function recovery and the number of required dialysis procedures were analyzed in the subgroup of patients with in-hospital recovery of kidney function. Baseline characteristics of the 273 patients in the two study groups were similar. All-cause mortality by Day 60 was 65.0% in the HF group and 65.5% in the HD group (hazard ratio, 0.98; 95% confidence interval, 0.71-1.33; P = 0.87). There were also no significant differences between the two groups in 30-day and in-hospital all-cause mortality or recovery of kidney function. Time to kidney function recovery and the number of required dialysis procedures were similar between the HF and the HD subgroup of patients with in-hospital recovery of kidney function. Dialysis treatment with intermittent high-volume predilution on-line HF in critically ill patients with AKI did not decrease mortality, improve recovery of kidney function or reduce the need for dialysis support compared to standard intermittent HD.

The effect of dialysis modality on phosphate control : haemodialysis compared to haemodiafiltration. The Pan Thames Renal Audit

Hyperphosphataemia is a primary risk factor for patients with end-stage kidney failure. Phosphate clearance by traditional thrice-weekly standard haemodialysis is inadequate for patients achieving recommended dietary protein goals. We investigated whether phosphate control was improved by adding convective clearance with haemodiafiltration. We audited pre-midweek session calcium and phosphate levels in 5366 adult patients, 4515 treated by haemodialysis and 851 by on-line haemodiafiltration. The cohorts were similar for age, sex and dialysis vintage. Serum phosphate was lower in the haemodiafiltration cohort (1.42 +/- 0.61 mmol/l) compared to the haemodialysis cohort (1.53 +/- 0.53 mmol/l; P < 0.001), as was the calcium-phosphate product (3.31 +/- 1.53 vs 3.5 +/- 1.33 mmol(2)/l(2), respectively; P < 0.001) despite a shorter treatment session time (3.68 +/- 0.44 vs 3.92 +/- 0.49 h; P < 0.001). Parathyroid hormone levels were similar. The results of this audit suggest that haemodiafiltration offers improved phosphate control compared to standard intermittent haemodialysis.

THE CLINICAL APPLICATION OF CRRT—CURRENT STATUS: Continuous Renal Replacement Therapies in Patients with Acute Neurological Injury

Acute neurological injury may occur in patients with end-stage kidney disease on dialysis. Less frequently, acute kidney injury requiring renal dialytic support develops following acute neurological injury. Surrounding any site of neurological injury there is a penumbra of damage which is potentially reversible. To maximize full potential neurological recovery in patients requiring renal dialytic support, it is important that treatments do not themselves cause further cerebral ischemia. Standard intermittent hemodialysis is associated with cerebral swelling even in healthy outpatients and often with episodes of intradialytic hypotension. Continuous modes of renal replacement therapy have been shown to cause fewer surges in intracranial pressure and greater stability of cerebral perfusion pressure than standard intermittent techniques. In patients with acute neurological injury, renal replacement therapy should be carefully adapted to minimize cardiovascular instability and reduce the rate of change of serum osmolality.

Practical guidance for dialyzing a hemodialysis patient following acute brain injury

The incidence of acute brain injury in chronic hemodialysis patients is increasing, as the dialysis population is becoming increasingly older, often hypertensive, at risk of ischemic and/or hemorrhagic stroke, and subdural hemorrhage. Standard intermittent hemodialysis treatments typically lead to an increase in cerebral swelling, which can exacerbate underlying cerebral damage. In critically ill patients, continuous modes of renal replacement therapy may be required, but depending upon the clinical condition, simple modifications to standard intermittent therapies may suffice, and allow effective delivery of renal replacement therapy, but ensure that patient outcomes both in terms of mortality and residual functional brain damage is no different between those with normal renal function and those on the chronic dialysis program.

CHRONIC RENAL FAILURE FOLLOWING ORTOTOPIC LIVER TRANSPLANTATION: AN EPIDEMIOLOGICAL STUDY.

P545 Aims: Chronic renal failure (CRF) is a recognized complication of organ transplantation and several risk factors there exist, linked both to patients and the procedure, which can favor its development. The aim of this study was to assess the incidence of post-transplantation CRF in a population of liver transplanted patients and to investigate the presence of possible risk factors for developing renal dysfunction. Methods: We performed a retrospective study on the liver-transplanted patients referring to liver transplantation ambulatory of “Tor Vergata” University of Rome and investigated the incidence of CRF and eventual need for renal replacement therapy (RRT). Furthermore, we searched for some possible risk factors for CRF development, such as systemic hypertension (SH), dyslipidemia, Diabetes Mellitus (DM), HBV and HCV status and calcyneurin inhibitors therapy. Results: From 1992 to today, 261 ortotopic liver transplantation have been performed at our Centre. In the post-transplantation period, 22 patients (8,4 %) developed chronic renal failure and were treated with standard intermittent hemodialysis (for a men time of 3 weeks). Among these, four male patients and one female subject have developed end stage renal disease (ESRD) and at present need chronic RRT. Further data about ESRD patients are reported in the Table below. One of them has died for cardiovascular complications during dialytic session.FigureAmong the remaining 17 patients, 5 subjects (29,5%) were HCV positive, 9/17 (52,9%) showed SH, 2/17 (11,8%) showed DM and 10/17 (58,8%) were treated with CsA. They partially recovered their renal function and are at present under conservative therapy. Conclusions: CRF proved to be a relatively common complication in our liver transplanted patients, confirming data reported in literature. Risk factors for developing renal dysfunction present in our patients are also cardiovascular risk factors and this could lead to an increase in mortality for cardiovascular pathology, particularly incident in uremic patients. It could be useful to pay attention to pre-transplant renal dysfunction, modifiable cardiovascular risk factors and immunosuppressant protocol in order to avoid CRF onset in liver transplanted patients, thus obtaining a reduction of morbidity and mortality and of the costs for the National Sanitary System.

Sustained low-efficiency dialysis for critically ill patients requiring renal replacement therapy

The replacement of renal function for critically ill patients is procedurally complex and expensive, and none of the available techniques have proven superiority in terms of benefit to patient mortality. In hemodynamically unstable or severely catabolic patients, however, the continuous therapies have practical and theoretical advantages when compared with conventional intermittent hemodialysis (IHD). We present a single center experience accumulated over 18 months since July 1998 with a hybrid technique named sustained low-efficiency dialysis (SLED), in which standard IHD equipment was used with reduced dialysate and blood flow rates. Twelve-hour treatments were performed nocturnally, allowing unrestricted access to the patient for daytime procedures and tests. One hundred forty-five SLED treatments were performed in 37 critically ill patients in whom IHD had failed or been withheld. The overall mean SLED treatment duration was 10.4 hours because 51 SLED treatments were prematurely discontinued. Of these discontinuations, 11 were for intractable hypotension, and the majority of the remainder was for extracorporeal blood circuit clotting. Hemodynamic stability was maintained during most SLED treatments, allowing the achievement of prescribed ultrafiltration goals in most cases with an overall mean shortfall of only 240 mL per treatment. Direct dialysis quantification in nine patients showed a mean delivered double-pool Kt/V of 1.36 per (completed) treatment. Mean phosphate removal was 1.5 g per treatment. Mild hypophosphatemia and/or hypokalemia requiring supplementation were observed in 25 treatments. Observed hospital mortality was 62.2%, which was not significantly different from the expected mortality as determined from the APACHE II illness severity scoring system. SLED is a viable alternative to traditional continuous renal replacement therapies for critically ill patients in whom IHD has failed or been withheld, although prospective studies directly comparing two modalities are required to define the exact role for SLED in this setting.

Renal replacement therapy in the patient with acute brain injury

The patient with an acute brain injury requiring renal replacement therapy presents a major problem in that conventional intermittent hemodialysis may exacerbate the injury by compromising cerebral perfusion pressure, either after a reduction in cerebral perfusion or because of increased cerebral edema. Compared with standard intermittent hemodialysis, the continuous forms of renal replacement therapy (CRRT) provide an effective therapy in terms of solute clearance, coupled with improved cardiovascular and intracranial stability. The disadvantage of CRRT is that anticoagulation may be required, and anticoagulants with systemic effects may provoke intracerebral hemorrhage, either at the site of damage or around the intracranial pressure monitoring device. Although peritoneal dialysis does not require anticoagulation, the clearances achieved are often less than those of CRRT, and sudden changes in intraperitoneal volume may provoke cardiovascular and thus intracranial instability.

Renal replacement therapy in the patient with acute brain injury

The patient with an acute brain injury requiring renal replacement therapy presents a major problem in that conventional intermittent hemodialysis may exacerbate the injury by compromising cerebral perfusion pressure, either after a reduction in cerebral perfusion or because of increased cerebral edema. Compared with standard intermittent hemodialysis, the continuous forms of renal replacement therapy (CRRT) provide an effective therapy in terms of solute clearance, coupled with improved cardiovascular and intracranial stability. The disadvantage of CRRT is that anticoagulation may be required, and anticoagulants with systemic effects may provoke intracerebral hemorrhage, either at the site of damage or around the intracranial pressure monitoring device. Although peritoneal dialysis does not require anticoagulation, the clearances achieved are often less than those of CRRT, and sudden changes in intraperitoneal volume may provoke cardiovascular and thus intracranial instability.

Ultrafiltration in Diuretic-Resistant Volume Overload in Nephrotic Syndrome and Patients with Ascites due to Chronic Liver Disease

Patients with nephrotic syndrome and those with cirrhosis are predisposed to salt and water retention due to reduced renal sodium excretion. Despite the prescription of low-sodium diets and diuretics, some patients develop refractory oedema. When other medical treatments have been ineffective, isolated ultrafiltration and hemofiltration have been successfully used to treat refractory nephrotic patients. Following fluid removal, patients become responsive to diuretics. In cirrhotic patients, re-infusion of ascites and paracentesis with albumin infusion have been reported to be equally effective in managing ascites refractory to diuretic and other standard therapies. Although isolated ultrafiltration has not been successful in controlling ascitic fluid, hemofiltration has been shown to be beneficial, whereas standard intermittent hemodialysis has been reported to be ineffective.

Anticoagulation in Patients With Acute Renal Failure Treated With Continuous Renal Replacement Therapies.

Although continuous renal replacement therapy (CRRT) provides greater cardiovascular and cerebrovascular stability compared to standard intermittent hemodialysis and/ or hemofiltration, to provide adequate solute removal, the CRRT circuit must function continuously. Patients with acute renal failure are usually prothrombotic, with activation of the contact coagulation cascade and reduction in the natural anticoagulants. Thus clotting within the extracorporeal circuit can be problematic. Coagulation requires activation of the coagulation protein enzymes, calcium, platelets, and contact with phospholipid cell surface or, in the case of the CRRT circuit, plastic tubing and the dialyzer membrane. This results in a platelet plug stabilized by cross-linking strands of fibrin. Anticoagulation regimes are either directed at trying to prevent contact activation of clotting factors and platelets or the administration of agents designed to prevent coagulation by blocking the coagulation cascade or platelet activation.