1. Pediatric CRRT Terminology
Helen Currier BSN, RN, CNN
Assistant Director, Renal/Pheresis
Texas Children’s Hospital
Houston, Texas
Concepts related to solute removal Convection Diffusion Formulas related to CRRT Sieving coefficient for a solute Ultrafiltrate concentration/plasma concentration Convective clearance (UFR x UF concentration)/arterial concentration Diffusive clearance (DFR x UF concentration)/arterial concentration Fluid replacement rate and net hourly fluid loss Components of a CRRT System Vascular accesses Blood lines Hemofilters Fluid-integrated CRRT systems Priming the CRRT system Anticoagulation of the CRRT system CRRT Procedures Procedures related to initiation of therapy Procedures related to monitoring therapy Procedures related to terminating therapy Potential problems encountered during CRRT Patient related concerns Dehydration Hypotension Electrolyte imbalance Acid/base imbalance Blood loss Air embolism Technical or procedure-related problems Small size of the patient Establishing vascular access Preventing heat loss Small size of pediatric hemofilters can prohibit the rate of replacement fluids in volumes used in adults Large size of extracorporeal priming volume Clotted hemofilter Poor ultrafiltration rate Blood leaks Malfunction of equipment Indications for CRRT in the critical care setting Fluid removal Patients w/acute renal failure (ARF) Patients w/cardiac instability and severe fluid overload Patients w/burns Patients w/rhabdomyolysis Solute removal Patients w/ARF or liver failure Patients w/inborn errors of metabolism (i.e. hyperammonemia) Patients w/toxic ingestions Patients w/pulmonary failure requiring extracorporeal membrane oxygenation (ECMO) CRRT outcomes research

3. History of Continuous Renal Replacement Therapy (CRRT)
Continuous arteriovenous approach first described for treatment of renal failure
Ultrafiltration isolated from hemodialysis circuit and the addition of a hemofilter
Hemofiltration technique proposed
SCUF and CAVH used by Paganini (MD) and Whitman (RN) at Cleveland Clinic
1960 – Belding Scribner first described a continuous arteriovenous approach for treatment of renal failure
1974 – Silversteins used a technique to perform ultrafiltration isolated from hemodialysis circuit and the addition of a hemofilter
1975 – Henderson proposed hemofiltration technique by collecting an ultrafiltrate of plasma and then reconstituting the blood volume with a fluid composition similar to normal plasma

4. History of Continuous Renal Replacement Therapy (CRRT)
1980s CRRT used in pediatrics
Pump-assisted CRRT introduced
CRRT considered state of the art therapy for treatment of acute renal failure
Standards of Clinical Practice for CRRT published by the American Nephrology Nurses’ Association (ANNA) and endorsed by the American Association of Critical Care Nurses (AACN)
Mid 1980s – CRRT used in pediatrics

5. History of Continuous Renal Replacement Therapy (CRRT)
Continued development of integrated blood pump and fluid balance equipment for CRRT
2002 Second pCRRT meeting in Orlando, FL
2004 Third pCRRT meeting in Orlando, FL
Mid 1980s – CRRT used in pediatrics

6. Test your knowledge Pediatric CRRT therapies are approximately
A. 40 years old
B. 30 years old
C. 20 years old
D. 10 years old

7. Test your knowledge Pediatric CRRT therapies are approximately
A. 40 years old
B. 30 years old
C. 20 years old
D. 10 years old

8. Indications for CRRT in the Critical Care Setting
Fluid removal
Solute removal

9. Basic Concepts of CRRT: Concepts Related to Fluid Removal or Ultrafiltration
Blood flow
Arteriovenous
Venovenous
Hydrostatic pressure
Other factors
Hematocrit
Plasma proteins
Transmembrane pressure
Ultrafiltration or fluid removal – removal of plasma volume across membrane driven by hydrostatic pressure

10. Basic Concepts of CRRT: Concepts Related to Solute Removal or Clearance
Convection – solute drag; hemofiltration
Diffusion – concentration gradient; hemodiafiltration
Dialysis or clearance – removal of solute across a membrane driven by diffusion and convention

11. Solute Mass Transfer in CRRT
Post-Dilution CVVH
CVVHD
Pre-Dilution CVVH
CVVHDF Qb
Qeff Qd Qr

12. Solute Molecular Weight and Clearance
Solute (MW) Sieving Coefficient Diffusion Coefficient
Urea (60) 1.01 ± ± 0.07
Creatinine (113) 1.00 ± ± 0.06
Uric Acid (168) 1.01 ± ± 0.04*
Vancomycin (1448) 0.84 ± ± 0.04**
*P<0.05 vs sieving coefficient **P<0.01 vs sieving coefficient

13. Comparison of Urea Clearance: CVVH vs CVVHD (Maxvold et al, Crit Care med. 2000 Apr;28(4):1161-5)
Study design
Fixed blood flow rate - 4 ml/kg/min
HF-400 (0.3 m2 polysulfone)
Cross over for 24 hrs each to pre-filter replacement fluid (CVVH) or Dx (CVVHD) flow at 2000 ml/hr/1.73 m2

14. Comparison of Urea Clearance: CVVH vs CVVHD (Maxvold et al, Crit Care med. 2000 Apr;28(4):1161-5)
p = NS
(mls/min/1.73 m2)
Urea Clearance
BFR = 4 mls/kg/min
FRF/Dx FR = 2 l/1.73 m2/hr
SAM = 0.3 m2

15. Methods of Continuous Renal Replacement Therapy

16. Definition of Acronyms and Terms
SCUF slow continuous ultrafiltration
CAVH continuous arteriovenous hemofiltration
CAVHD continuous arteriovenous hemodialysis
CVVH continuous venovenous hemofiltration
CVVHD continuous venovenous hemodialysis
CVVHDF continuous venovenous hemodiafiltration

17. Continuous Renal Replacement Therapy
Advantages
Slower blood flows
Slower UF rates
Adjust UF rates with hourly patient intake
Increased cytokine (bad humors) removal?
Disadvantages
Prolonged anticoagulation
Increased cytokine (good humors) removal?

18. The Pediatric Ideal: CRRT Equipment
Separate and accurate pumps and scales for each component of CRRT
Range of blood flows with a minimum of 20ml/min
Thermoregulation
Maximum safety features
Separate and accurate pumps and scales for each component of CRRT (i.e., UF, replacement fluid, dialysate)

19. The Pediatric Ideal: CRRT Circuit
Minimum priming volume with low resistance
Exchangeable components
Biocompatible membrane