1 prismaflex crrt intro - seg 1 (2007)
TRANSCRIPT
PrismaFlex STEPP
Basic CRRT Principles
®
Course ObjectivesBy the end of the Gambro CRRT training course
the participant will be able to:
• Define CRRT and the associated therapies
• Discuss the basic CRRT principles
• Discuss the basic principles of the solute transport mechanisms
• Identify the clinical indications for administering CRRT, including
an overview of patient selection and therapy application
• Have a working knowledge of basic CRRT machine set up, run, end
treatment and troubleshooting skills.
• Describe the CRRT machine’s safety management features,
pressure monitoring and fluid balance principles.
Continuous Renal Replacement Therapy (CRRT)
““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, Nov 1996
CRRT closely mimics the native kidney in treating ARF and fluid overload
Why CRRT?
Removes large amounts of fluid and waste products over time
Tolerated well by hemodynamically unstable patients
CRRT Treatment Goals
Maintain fluid, electrolyte, acid/base balance
Prevent further damage to kidney tissue
Promote healing and total renal recovery
Allow other supportive measures; nutritional
support
Determinants of Outcome
Initiation of Therapy• Ronco Study• Gettings Study• ADQI Consensus Initiative - Rifle Criteria
Dose• Ronco Study• Kellum Meta-Analysis• Saudan Study
Risk
Injury
Failure
Loss
ESRD
GFR Criteria Urine Output Criteria
Increased creatinine x 1.5 or GFR decrease >25% UO <,0.5ml/kg/hr x 6 hours
Increased creatinine x 2 or GFR decrease >50%
UO <0.5 ml/kg/hr x 12 hours
Increased creatinine x 3 or GFR decrease >75% or
Serum Creatinine > 4mg/dlUO <0.3 ml/kg/hr x 24 hours
or anuria x 12 hours
Persistent ARF= complete loss of renal function >4 weeks
End-stage renal disease (>3 months)
EarlyInitiation
Summary Evidenced Based Research reports that
patient survival is improved by:
•Early initiation: •Utilization of RIFLE Criteria
•Minimum dose delivery of 35 ml/kg/hr • eg. 70 kg patient = 2450 ml/h
Effects of different doses in CVVH on outcomes of ARF – C. Ronco M.D., R. Bellomo M.D. Lancet 2000; 356:26-30.
Anatomy of a Hemofilter
• 4 External ports • blood and dialysis fluid
• Potting material • support structure
• Hollow fibers • Semi-permeable
membrane
• Outer casing
CRRT Transport Mechanisms
Molecular Transport Mechanisms
Ultrafiltration
Diffusion
Convection
Adsorption
Fluid Transport
Solute Transport}
Ultrafiltration
•Movement of fluid through a semi-permeable membrane caused by a pressure gradient
•Positive, negative and osmotic pressure from non-permeable solutes
Blood Out
Blood Into waste
(to patient)
(From patient)
HIGH PRESSLOW PRESS
Fluid VolumeReduction
Ultrafiltration
Molecular WeightsDaltons
• Inflammatory Mediators (1,200-40,000)
“small”
“middle”
“large”
Diffusion
•Movement of solutes from an area of higher concentration to an area of lower concentration.
•Dialysate is used to create a concentration gradient across a semi-permeable membrane.
Hemodialysis: Diffusion
Dialysate In
Dialysate Out(to waste)
Blood Out
Blood In
(to patient)
(from patient)
HIGH CONCLOW CONC
Convection
•Movement of solutes with water flow, “solvent drag”.
•The more fluid moved through a semi-permeable membrane, the more solutes that are removed.
•Replacement Fluid is used to create convection
to waste
HIGH PRESSLOW PRESS
Repl.Repl.SolutionSolution
Hemofiltration: Convection
Blood Out
Blood In
(to patient)
(from patient)
Electrolytes & pH Balance
Another primary goal for CRRT, specifically:• Sodium• Potassium• Calcium• Glucose• Phosphate• Bicarbonate or lactate buffer
Dialysate and replacement solutions are used in CRRT to attain this goal.
Adsorption
Molecular adherence to the surface or interior of the membrane.
0
20
40
60
80
100
Cle
aran
ce in
%
35.000 55.00020.0005.0002.500Urea(60)
Albumin(66.000)
Myoglobin(17.000)
65.000Creatinine
(113)
Kidney
Convection
Diffusion
Small vs. Large Molecules Clearance
What is the transport mechanism associated
with dialysate and replacement solutions?
Effluent
Pre Blood Pump Replacement: Convection
Blood
Flow Control Unit – Pumps
Dialysate: Diffusion
Effluent Flow Rate
Effluent = Total Fluid Volume:
•Patient Fluid Removal•Dialysate Flow•Replacement Flow•Pre-Blood Pump Flow
CRRT Modes of Therapy
SCUF - Slow Continuous Ultrafiltration
CVVH - Continuous Veno-Venous Hemofiltration
CVVHD - Continuous Veno-Venous HemoDialysis
CVVHDF - Continuous Veno-Venous HemoDiaFiltration
SCUFSlow Continuous UltraFiltration
Primary therapeutic goal:•Safe and effective management of
fluid removal from the patient
SCUFSlow Continuous UltraFiltration
EffluentPump
Infusion or Anticoagul
ant
Blood Pump
PBPPump
Effluent
Access
Return
CVVHDContinuous VV HemoDialysis
Primary therapeutic goal:• Small solute removal by diffusion• Safe fluid volume management
Dialysate volume automatically removed through the Effluent pump
Solute removal determined by Dialysate Flow Rate.
CVVHDContinuous VV HemoDialysis
Hemofilter
EffluentPump
Effluent
Access
Return
DialysatePump
Dialysate
Fluid
Blood Pump
Infusion or Anticoagul
ant
PBPPump
Dialysate Solutions
• Flows counter-current to blood flow
• Remains separated by a semi-permeable membrane
• Drives diffusive transport • dependent on concentration gradient and flow rate
• Facilitates removal of small solutes
• Physician prescribed
• Contains physiologic electrolyte levels
• Components adjusted to meet patient needs
CVVH: Continuous VV Hemofiltration
Primary Therapeutic Goal: • Removal of small, middle and large sized solutes • Safe fluid volume management
• Replacement solution is infused into blood compartment pre or post filter• Drives convective transport• Replacement fluid volume automatically removed
by effluent pump
Solute removal determined by Replacement Flow Rate.
CVVHContinuous VV Hemofiltration
EffluentPump
Blood Pump
Effluent
Access
Return
ReplacementPump 1
Replacement
Pump 2
Replacement 1
Replacement 2
Infusion or Anticoagul
ant
PBPPump
Pre-Dilution Replacement Solution
•Decreases risk of clotting
•Higher UF capabilities
•Decreases Hct. In filter
Hemofilter
EffluentPump
Blood Pump
PBPPump
Effluent
Access
Return
ReplacementPump
Replacement
Fluid
Infusion or Anticoagul
ant
Post-Dilution Replacement Solution
•Consider lowering replacement rates (filtration %)
•Higher BFR (filtration %)
•Higher anticoagulation
•More efficient clearance (>15%)
Hemofilter
EffluentPump
Blood Pump
Effluent
Access
Return
ReplacementPump
Replacement
Fluid
ReplacementPump
Replacement
Fluid
PBPPump
Infusion or Anticoagul
ant
Replacement Solutions
• Infused directly into the blood at points along the blood pathway
• Drives convective transport• Facilitates the removal of small middle and
large solutes• Physician Prescribed • Contains electrolytes at physiological levels • Components adjusted to meet patient needs
CVVHDFPrimary therapeutic goal:
• Solute removal by diffusion and convection• Safe fluid volume management• Efficient removal of small, middle and large
molecules
Replacement and dialysate fluid volume automatically removed by effluent pump
Solute removal determined by Replacement + Dialysate Flow Rates.
CVVHDFContinuous VV HemoDiaFiltration
EffluentPump
Effluent
Access
Return
DialysatePump
Dialysate
Fluid
Blood Pump
ReplacementPump
Replacement
Fluid
PBPPump
Infusion or Anticoagul
ant