Renal replacement therapy

See Hemodialysis The main objective renal replacement therapy is to mitigate life-threatening consequences, thereby preventing death from uremia.

Achieved by dialysis or renal transplantation.

Transplantation improves longevity, lifestyle and improves cost compared to dialysis.

Indications for renal replacement therapy in patients with chronic kidney disease include:

Severe metabolic acidosis




Intractable volume overload

Failure to thrive and malnutrition

Peripheral neuropathy

Intractable gastrointestinal symptoms

In asymptomatic adult patients, a glomerular filtration rate (GFR) of 5-9 mL/min/1.73 m², irrespective of the cause of the CKD or the presence of absence of other comorbidities.

Among critically ill patients with acute kidney disease, and accelerated renal replacement treatment is not associated with a lower risk of death at 90 days than a standing strategy (theSARRT-AKI investigators).

Extracorporeal kidney replacement therapy requires vascular access and pump driven extracorporeal circuit that perfuses blood over a semipermeable membrane across which accumulated solutes, salt, and water are exchanged.

The hemodialyzers used as  artificial kidneys during kidney replacement therapy are generally composed of a semi permeable cellulose or synthetic polymer membranes fabricated as hollow fibers through which blood is perfused.

They allow for an exchange surface of 1 to 2.5 m² in a compact cartridge.

Vascular access utilizes a large-bore, double lumen catheter inserted into internal jugular vein or femoral vein.

These vascular sites are equivalent in terms of efficacy, safety, and similar risks of hemorrhage.

Femoral catheters carry a higher risk of infection than  rates with jugular catheters in patients with BMI greater than 28.

Subclavian vein cannulation is not preferred because of greater risk of complications.

Extracorporeal kidney replacement therapy is provided as prolonged intermittent hemodialysis or a form of continuous kidney replacement therapy.

Continuous kidney replacement therapy mitigates the risk of hemodynamic instability during intermittent hemodialysis.

observational studies suggest advantages of continuous treatment with respect to hemodynamic tolerance, patient survival, and recovery of kidney function these findings were not confirmed in a randomized control trial which found at 60 days survival rate was similar to intermittent hemodialysis and continuous replacement therapy at 32 and 33%, respectively, with no significant difference in the incidence of treatment associated hypertension or recovery of kidney function.

in patients with increased cerebral pressure, intracerebral edema, or both who are susceptible to impaired cerebral perfusion from osmotic dysequilibrium in dialytic hypotension during intermittent hemodialysis; continuous kidney replacement therapy is preferred for these patients.

With intermittent hemodialysis, solute is removed predominately by diffusion and treatment is provided 3 to 7 times a week, with each session lasting 3 to 6 hours.

To achieve sufficient volume and solute removal a high dialysate and blood flow rate is required.

A rapid solute removal can help in treating life-threatening acid base and electrolyte disturbances and drug intoxication or poisonings that are due to dialyzable substances.

Rapid ultrafiltration to decrease volume overload during relatively short treatment sessions predisposes to hypertension.

The rapid lowering of serum urea levels, particularly in the case of prolonged elevations, may result in neurologic symptoms ranging from headache to impaired sensorium and rarely seizures as a result of delayed equilibration of solutes which leads to cerebral cells swelling from osmotic shifts of fluid.

The rapid reduction of antibiotics may require more prolonged intermittent kidney replacement.

Anticoagulant therapy is often provided due to the common complication of clotting in the extracorporal circuit: it seeks to maintain circuit patency but it can increase the risk of bleeding and sometimes is omitted, particularly when treatment is shorter or higher blood flow rates are used as with the case of intermittent hemodialysis.

Anticoagulation is most commonly utilized with unfractionated or low molecular weight heparin or, during continuous treatment by regionally inhibiting the coagulation cascade with an infusion of citrate into the extracorporeal circuit to chelate calcium and calcium infusion to maintain systemic ionized calcium levels.


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