Volume Management by Renal Replacement Therapy in Acute Kidney Injury

Abstract

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.

THE CLINICAL APPLICATION OF CRRT—CURRENT STATUS: Modalities of Continuous Renal Replacement Therapy: Technical and Clinical Considerations

“…Previous reviews (6,7) have discussed the fundamental operational characteristics of CRRT and will not be reiterated here. More recently, the acute dialysis quality initiative (ADQI) published a consensus on fluid (8) and volume management in AKI (9) relevant to the present discussion.…”

The Wearable Artificial Kidney, Why and How: From Holy Grail to Reality

“…However, CRRT machines are not suitable to treat CKD patients, as they require constant nursing time to treat a single patient. In addition, they are heavy, tethered to a wall electrical outlet, and require large volumes of sterile replacement fluid or dialysate (23). Whilst treated, patients are unable to mobilize and perform their activities of daily life.…”

Can dialyzer membrane selection affect outcomes in patients with acute kidney injury requiring dialysis?

“…18 A new generation of synthetic and semisynthetic dialyzer membranes was introduced in the 1980s, these membranes potentially had variable permeability to both middle-sized solutes and water. Hydraulic permeability was primarily related to membrane thickness, and low flux was defined as K UF o8 mL/ h/mmHg, and high flux above this value.…”