CRRT

MRZ

Introduction to CRRT - DefinitionsCRRT = Continuous Renal Replacement

Therapy

Defined as“Any extracorporeal blood purification

therapy intended to substitute for impaired renal function over an extended period of time and applied for or aimed at being applied for 24 hours /day.” *

* Bellomo R., Ronco C., Mehta R, Nomenclature for Continuous Renal Replacement Therapies, AJKD, Vol 28, No. 5, Suppl 3, November 1996

Modalities The various CRRT treatment modalities

are: SCUF: Slow continuous

ultrafiltration CVVH: Continuous veno-venous

hemofiltration CVVHD: Continuous veno-venous

hemodialysis CVVHDF: Continuous veno-venous

hemodiafiltration

Indications for CRRT Renal Indications Non-obstructive oliguria (u/o<400 ml/24h) or

anuria Severe acidemia (pH,<7.1) due to metabolic

acidosis Azotemia(urea>30 mmol/l) Hyperkalemia Progressive severe dysnatremia Rhabdomyolysis (Crush Injuries) Hyperphosphatemia ARF in the context of MSOF

Indications for CRRT cont,d• Potential Non-Renal Indications• Significant organ edema (especially lung)• Sepsis• SIRS (Systemic Inflammatory Response Syndrome)• MSOF (Multi System Organ Failure)• ARDS• Fulminant hepatic failure• Severe burns• Cerebral edema• Tumor lysis syndrome• Coagulopathy requiring large amounts of blood products in

patients at high risk of developing ARDS or pulmonary edema• Cardiopulmonary bypass• Suspected uremic organ involvement (percarditis)• CHF (Congestive Heart Failure)• Lactic acidosis• Drug overdose with a toxin removable by extracorporeal

therapy

CRRT Treatment Goals

Maintain fluid, electrolyte, acid/base balance.

Prevent further damage to kidney tissue.

Promote healing and renal recovery

Allow other supportive measures; nutritional support

Therapy Options

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Effluent

Replacement(pre or post dilution)

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Effluent

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Effluent

Dialysate

Replacement(pre orpost dilution)

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Effluent

Dialysate

SCUF CVVH CVVHD CVVHDF

SCUFSlow Continuous Ultrafiltration

Maximum Patient Fluid RemovalRate = 2000 ml/hr

Therapy OptionsAccess

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Effluent

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SCUF Slow Continuous Ultrafiltration

Primary therapeutic goal:Safe management of fluid removal

UF rate ranges up to 2 L/Hr No dialysate No replacement fluids Large fluid removal via ultrafiltration Blood Flow rates = 10-180 ml/min

CVVH

Continuous Veno-Venous Hemofiltration

Replacement(pre or post dilution)

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Effluent

Therapy Options

When prime with CVVH mode, Maximum Replacement Flow = 4500 ml/hrMaximum Patient Fluid Removal Rate = 1000 ml/hr

CVVHContinuous VV Hemofiltration

• Primary therapeutic goal:

• convective solute removal and safe mgmt. of fluid volume

• UF rate ranges 12-20 L/24 hours (>500 ml/hr)

• Requires replacement solution to drive convection

• No dialysate

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Replacement

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Effluent

• Pre-Dilution – Lowers HCT, decreases risk

of clotting– Higher UF– UF chemistries do not reflect

true plasma solute losses

Replacement Fluids

CVVHD

Continuous Veno-Venous Hemodialysis

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Effluent

Dialysate

Therapy Options

Maximum Patient Fluid Removal Rate = 1000 ml/hrMaximum dialysate flow = 2500ml/hr

• Primary therapeutic goal:• Solute removal by diffusion

• Safe fluid volume management

• Requires dialysate solution

• UF rate ranges 2-7 L/24 hours (~300 ml/hr)

• Dialysate Flow rate = 15-45 ml/min (~1-3 L/hr)

• Blood Flow rate = 10-180 ml/min

• No replacement solution

• Solute removal determined by Dialysate Flow rate.

CVVHDContinuous VV Hemodialysis

CVVHDF

ContinuousVeno-VenousHemodiafiltration

Replacement(pre or post dilution)

Dialysate

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Effluent

Therapy Options

Maximum Pt. fluid removal rate = 1000 ml/hr

Maximum Replacement Flow = 2000 ml/hr

Maximum Dialysate Flow = 2500 ml/hr

CVVHDFContinuous VV Hemodiafiltration• Primary therapeutic goal:• Solute removal by diffusion and convection

• Safe fluid volume mgmt.

• Combines CVVH and CVVHD therapies

• UF rate ranges 12-20L/24hr

• Uses dialysate solution

• Uses replacement solution

• Blood Flow rate = 10-180ml/min

• Dialysate Flow rate = 15-45 ml/min

Therapy Options

TPETherapeuticPlasmaExchange

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Plasma

Replacement

Effluent

Maximum plasma exchange rate =2000ml/h

Maximum patient plasma loss = 1000ml/h

Transport principle

Diffusive vs. Convective therapies

diffusion convectiondiffusion +convection

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