1. Accuracy of CVVH on ECMO : A comparison of IV pump versus Braun Diapact driven systems
Matthew L. Paden, MD
Division of Pediatric Critical Care
Emory University
Children’s Healthcare of Atlanta at Egleston

2. The Clinical Problem
Multiple ECMO/CVVH patients who are 10+ liters positive on paper, yet are clinically dehydrated
Hypothesis : Both IV pump and Braun Diapact driven CVVH systems when used with ECMO have error rates greater than 5% / hour.

3. Methods for CRRT on ECMO
Commercially available CRRT machines
B Braun Diapact
Edwards Aquarius
Fresenius
Gambro Prisma/Prismaflex
Advantage – Standardized equipment, “built for the purpose”

4. Methods for CRRT on ECMO
IV Pump Driven
Described by Weber, et al 1998
IV pumps used to create ultrafiltrate and deliver replacement fluid
Ultrafiltrate is measured using a urometer
Advantage – low cost, no additional training for ECMO specialists, less extracorporeal blood volume

7. The Problem
Inaccuracy has been described in CRRT in patients not on ECMO
The pumps are the problem
PCRRT 2000 –
7% extra ultrafiltrate removed
2% less replacement fluid delivered
ASAIO 1992 –
Up to 12.5% error rate
Error correlates with pressure drop across membrane and pump type

8. Alaris Pump Accuracy
Sucosky et al. Awaiting publication. 2008

9. Methods Two identical saline primed ECMO circuits
Stockert S3, ½ inch drain, 3/8 inch return
4.5 m2 Medtronic oxygenator
PAN 6 hemofilter
CVVH prescribed : IV pump vs. Diapact
Net even fluid balance
Varying ultrafiltration rates (0.5 – 2 L / hour)
Hourly weights of UF/Replacement bags, circuit pressures

10. Results 48 hourly measurements 26 hours Alaris 22 hours Diapact
No correlation between error rate and
Prescribed ultrafiltration rate
ECMO flow rate
CVVH blood flow rate

11. Results - Alaris
Created a median 0.8% less ultrafiltrate per hour than prescribed (+7% to -12%)
Delivered a median of 4.3% less replacement fluid per hour than prescribed (+3% to -25%)
NET 3.5% of prescribed UF per hour dehydration to patient

12. Examples with Alaris
4 kg neonate on ECMO with 100 ml/hour prescribed UF rate and even fluid balance
84 ml (21 ml/kg) fluid negative per day
10 kg child on ECMO with 300 ml/hour prescribed UF rate and even fluid balance
252 ml (25 ml/kg) fluid negative per day
45 kg child on ECMO with 2000 ml/hour prescribed UF rate and even fluid balance
1.68 L (37 ml/kg) fluid negative per day

13. Results - Diapact
Created a median 1% more ultrafiltrate per hour than prescribed (+6% to -8%)
Delivered a median of 1% more replacement fluid per hour than prescribed (+10% to -7%)

14. Examples Braun Accurate when looking at medians over time
Hourly variation could be important in a hemodynamically unstable patient
Hourly Fluid Balance -5 35 10
-40
-10
-30

15. Conclusions In this in vitro CVVH/ECMO model
Both the Alaris and Diapact methods had error rates that could be clinically significant
Careful physical assessment of the patient’s volume status is necessary
Further work is needed to develop more a accurate fluid management system for CRRT on ECMO