Continuous Renal Replacement Therapy
Continuous Renal Replacement Therapy offers many benefits to AKI patients.
CRRT comes in several forms. They include: slow continuous ultrafiltration, continuous venovenous hemodialysis, hemofiltration, hemodiafiltration, continuous arterio-venous hemofiltration, and slow low-efficiency daily dialysis.
Patients who are hemodynamically unstable
CRRT was invented as a more hemodynamically-stabilizing alternative to IHD.32 Through continuous and slow fluid removal, CRRT mimics the kidneys in regulating water, electrolytes, and wastes 24 hours a day over several days.1,31
Patients with gross fluid overload or receiving large volumes of fluid daily
In CRRT, fluid removal occurs continuously by ultrafiltration at an established hourly rate. Patients with AKI receiving CRRT have had reduced fluid accumulation compared with those on IHD. Preventing fluid overload is important because it is associated with mortality in patients with AKI.6
Patients with increased intracranial pressures
Among CRRT’s advantages, relative to other RRT, is the prevention of changes in intracerebral water.32 One study found an increase in brain water content after IHD but no such change following CRRT.6 With its slower rate of urea clearance, CRRT can be safer than IHD in patients at risk of cerebral edema that is part of dialysis disequilibrium syndrome.32
Patients requiring increased metabolic clearance
CRRT can control acid–base and electrolyte status, including phosphate and calcium balance, while providing protein-rich nutrition and uremic control.32 As such, CRRT prevents or offsets the effects of metabolic abnormalities. It can begin promptly for patients who have these abnormalities and who require renal support.32
Patients requiring clearance of appropriate larger molecules
Depending on its set up, CRRT can perform hemodialysis, hemofiltration, and hemodiafiltration. Hemofiltration and hemodiafiltration can remove larger molecules like myoglobin or cytokines. CRRT’s abilities of hemofiltration and hemodialysis also filter out small solutes and mid-sized molecules, such as interleukin-1β, interleukin-6, and interleukin-8, that are involved in sepsis.31
Patients needing to avoid rebound in certain intoxications
CRRT can treat the effects from nephrotoxins, such as radiocontrast medium for coronary angiography. A type of CRRT, peri-procedural continuous veno-venous hemofiltration (CVVH), can control effects of contrast nephropathy after coronary interventions in high-risk patients with advanced chronic renal insufficiency.32
CRRT is the preferred renal replacement therapy by many clinicians for patients with AKI who are hemodynamically unstable.
CRRT is RRT delivery 24 hours a day. Embodying an extracorporeal process, the CRRT device ensures removal by catheter of blood and its circulation via a peristaltic blood pump through a semipermeable membrane before the blood is returned to the patient.31 Many clinicians prefer to use CCRT for patients with AKI who are hemodynamically unstable. Its slow but continuous urea clearance helps to avoid spikes in blood urea nitrogen (BUN) levels.30 Relative to intermittent RRT, including intermittent hemodialysis (IHD), CRRT may offer more precise fluid management.1,17 CRRT’s other advantages can include improved management of acid–base status, electrolyte balance and the swings associated with intracerebral water.31,32 One study found an increase in brain water content after IHD but no such change following CRRT.18
Use of CRRT for the management of AKI is associated with a lower risk for chronic dialysis compared with IHD.
AKI is associated with an increased risk of long-term dialysis dependence. Acute RTT modality type may impact this risk. Patients with AKI on CRRT have been less likely to require chronic dialysis compared with those treated with IHD.25, 26, 27, 28 Patients receiving CRRT have had reduced fluid accumulation compared with those on IHD.17 Preventing fluid overload is important because it is associated with mortality in patients with AKI.6 CRRT as initial therapy for AKI in the ICU was found to have lower 5-year total costs compared to intermittent RRT. Average base-case cost totals were $37,780 versus $39,448. The difference in cost was due in part to fewer CRRT patients requiring long-term dialysis.11 CRRT can be delivered across different ICUs in the same hospital. Clinicians may want to develop a care model to oversee all RRT regardless of setting. As part of such a model, metrics can be measured, such as time between CRRT order and initiation'.33
Use of CRRT for AKI management has been associated with a lower risk of chronic dialysis compared with IHD.
That's how long CRRT runs compared to IHD which runs 6-12 hours/day.19, 20, 30
That's how much money patients save over five years when they choose CRRT vs. IHD.11
.75 Hazard Ratio
That's the chronic dialysis hazard ratio (95% CI) for CRRT vs. IHD.25