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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