accuracy of cvvh on ecmo : a comparison of iv pump versus braun diapact driven systems
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
Accuracy of CVVH on ECMO : A comparison of IV pump versus Braun Diapact driven systems
Matthew L. Paden, MDDivision of Pediatric Critical Care
Emory UniversityChildren’s Healthcare of Atlanta at Egleston
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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
Sucosky et al. Awaiting publication. 2008
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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