1. Norma J Maxvold Pediatric Critical Care
PCRRT on ECMO
Norma J Maxvold
Pediatric Critical Care

2. PCRRT on ECMO What is the incidence of PCRRT in ECMO?
How does it differ to standard PCRRT
Where do you put the filter?
What are the risks?
What factors effect solute clearance?
Weaning ECMO in an anuric child
What outcome data is available?

3. PCRRT on ECMO Incidence (ELSO registry 1997)
Neonatal ECMO = 14% require PCRRT
Pediatric ECMO = 31% require PCRRT

4. PCRRT on ECMO vs Standard PCRRT

5. PCRRT on ECMO vs Standard PCRRT

6. Hemofiltration on ECMO

7. Risks of PCRRT on ECMO
Excessive ultrafiltration (VA ECMO will support hemodynamics independent of volume status)
due to ultrafiltration controller error
due to higher then greater blood flow rate

8. RESULTS (Smoyer et al, CRRT 1997)
Trilogy Pump: Accuracy over Range of Flow Rates
% Error
IV Pump Flow Rate (ml/hr)

9. Clinical Scenario 3 kg infant on VA ECMO
SCUF for 4 days at 250 cc/day net
K 4.5 mEq/L, Phos 5.7 mg/dl
Albumin 3.8 gm/dl
Na prior to SCUF 139
IVF were TPN, antibiotics

10. Clinical Scenario Lab data-4 days later
Euvolemic, Anuric
Na 118 mEq/L, Cl 74 mEq/L

11. Clinical Scenario
3 kg child with intravascular blood volume of 240 ccs
Net Na loss was based upon Na content of ultrafiltrate/day ~120 mEq or 40 mEq/kg
Without adequate replacement fluid or counter current dialysis excessive solute loss occurs

12. What determines Solute Clearance?
Blood Flow Rate (BFR)
Dialysate Flow Rate (DxFR) in CVVHD or Replacement Flow Rate (ReplFR) in CVVH
Surface Area of membrane/porosity of the membrane

13. Comparison of Urea Clearance: CVVH vs CVVHD (Maxvold et al, Crit Care Med April 2000)
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

14. Impact of Surface Area of hemofilter-1 (Maxvold et al, ELSO 1994)
70 kg child on VA ECMO and anuric
PCRRT BFR 200 mls/min
mls/hr
HF with 0.24 m2

15. Impact of Surface Area of hemofilter-2 (Maxvold et al, ELSO 1994)
Over 24 hours of hemofiltration the following metabolic changes occurred
Bun dropped from mg/dl
Potassium increased from meq/l
HCO2 dropped from meq/l
(we be in trouble!!)

16. Impact of Surface Area of hemofilter-3
The hemofilter was changed from the 0.24 m2 to a 1.7 m2 HD membrane and over the next 24 hours
Bun dropped mg/dl (to rapid of a shift)
K meq/l
HCO2 22-> 40 meq/l
pH increase from 7.15 to 7.75

17. Metabolic consequences when weaning ECMO
Mixed metabolic and respiratory acidosis
hypotension
need for blood transfusions with secondary hypocalcemia and hyperkalemia

18. Anticipate Metabolic Consequences
plan to decrease the serum potassium
plan to make alkalotic
THESE ARE MOST IMPORTANT IN A PATIENT WHO IS ANURIC/OLIGURIC
COMMUNICATION PRIOR TO DECISION

19. Post ECMO Renal Effect (Meyers et al, Peds Crit Care Coll, Portland, OR 1999)
35 children requiring HF on ECMO/8 yrs
20 died (withdrawn) on ECMO and CRRT due to lack of recovery of underlying cause
15 survived ECMO requiring ongoing PCRRT
14/15 had recovery of renal function within 7-10 days post discontinuation of ECMO

20. PCRRT and ECMO
Especially in the smaller children and infants solute clearance on ECMO is greater then standard PCRRT due to the relatively high blood flow rates
Ultrafiltration error may not be easily recognized due to the maintenance of hemodynamic stability that ECMO gives

21. PCRRT and ECMO These are the sickest of the sick
ECMO is not a substitution for dialysis
Recovery of renal function will occur in majority of patients within days in those who had normal renal function prior to need for ECMO