Transcript Slide 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
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.
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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”
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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
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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
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Alaris Pump Accuracy
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Sucosky et al. Awaiting publication. 2008
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
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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
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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
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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
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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%)
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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
10
35
-40
-5
0
-10
-30
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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
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