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Pediatric CRRT: Ultrafiltration Control. William E. Smoyer, M.D. Pediatric Nephrology University of Michigan. Introduction. Ultrafiltration control not a widely accepted concern for CRRT Often not regulated in adult ICUs No reports of significant volume imbalances - PowerPoint PPT Presentation
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Pediatric CRRT:Ultrafiltration Control
William E. Smoyer, M.D.
Pediatric Nephrology
University of Michigan
Introduction
• Ultrafiltration control not a widely accepted concern for CRRTOften not regulated in adult ICUsNo reports of significant volume imbalances
• Industry standards for pump error - 5-10%
• Few reports on CRRT pump accuracy (in vitro) 1,2
• Anecdotal reports of severe unanticipated volume depletion in several small children on CRRT
1 Jenkins R et al. ASAIO J. 38:808, 1992
2 Roberts M et al. Int J Artif Organs. 15:99, 1992
CRRT Pump Accuracy Study
• Hypothesis: Unanticipated fluid losses with CVVHD are clinically significant and result from variable pressure loads on the pumps
• Study Design:1) To prospectively analyze the accuracy of available IV
pumps during CRRT in vivo 2) To prospectively analyze the effects of blood flow,
total dialysate (D) + ultrafiltrate (UF) flow, and net UF flow rates on pump pressures in vitro
Methods
• Patients4 infants and children requiring CRRT (CVVHD)
• CRRT CircuitHemofilters:
Renal Systems; Renaflo II HF 400 (SA 0.30 m2) Hospal; Multiflow - 60 (SA 0.60 m2) Minntech; Minifilter Plus (SA 0.07 m2)
Blood Flow: 4 cc/kg/min (Gambro AK 10) IV Pumps:
Medex Trilogy / Alaris Gemini / Baxter Colleague 3
Methods
• In Vivo Data CollectionBags weighed on infant scale accurate to +0.5 ml (g)Sequential 1 hour measurements of:
“Set” vs. “Measured” dialysate inflow “Set” vs. “Measured” ultrafiltrate outflow
• In Vivo Data Analysis (1049 total pump-hours)Analysis of absolute hourly error for each pumpAnalysis of mean % error for each pumpComparison of each pump’s mean % error:
At variable pump flow rates During use for dialysate (inflow) vs. ultrafiltrate (outflow)
CRRT Pump Accuracy-Trilogy
0 100 200 250 300 400 500 600 700 800 900 1000-6
-5
-4
-3
-2
-1
0
1
2
3
Pump Flow Rate(ml/min)
Dialysate
Ultrafiltrate
Pump Accuracy over a Range of Flow Rates:Medex Trilogy
(n = 976 pump-hours)
CRRT Pump Accuracy-Gemini
0 100 200 250 300 400 500 600 700 800 900 1000-1
0
1
2
3
4
5
6
7
8Pump Flow Rate
(ml/min)Dialysate
Ultrafiltrate
Pump Accuracy over a Range of Flow Rates:Alaris Gemini
(n = 67 pump-hours)
CRRT Pump Accuracy-Colleague 3
0 100 200 250 300 400 500 600 700 800 900 1000-2
-1
0
1
2
3
4
5
6
7
Pump Flow Rate(ml/min)
Dialysate
Ultrafiltrate
Pump Accuracy over a Range of Flow Rates:Baxter Colleague 3
(n = 6 pump-hours)
CRRT Pump Accuracy-Combined
Trilogy Gemini Colleague 3 Combined-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6Dialysate
Ultrafiltrate
Cumulative
Mean Individual and Combined Pump Accuracyfor All Flow Rates
(n = 1049 pump-hours)
(Cumulative Error = Dialysate + Ultrafiltrate Error = Net Pump Error to Patient)
Results of In Vivo Studies
• Dialysate Pump Error (all pumps):Range: -6.8 +0.5% (-34.3 +4.7 ml/hr)Mean: -4.0%
• Ultrafiltrate Pump Error (all pumps):Range: -1.5 +7.4% (-13.7 +16.2 ml/hr)Mean: +0.9%
• Cumulative Pump Error (all pumps):Range: -7.9 +0.9% (-48.5 +9 ml/hr)Mean: -5.2%
Effect of Blood Flow on CRRT Pump Pressures-Trilogy
0
25
50
75
100
125
0 100 200 300
Blood Flow Rate(ml/min)
Dialysate Pre-Pump
Dialysate Post-Pump
UF Pre-Pump
UF Post-Pump
Blood Flow Rate vs. Pump Pressure:Medex Trilogy
*
*
*
+
+
+
(* = P < 0.05 vs. Blood Flow Rate 100)(+ = P < 0.05 vs. Blood Flow Rate 100)
Effect of Blood Flow on CRRT Pump Pressures-Colleague 3
0
25
50
75
100
125
0 100 200 300
Blood Flow Rate(ml/min)
Dialysate Pre-Pump
Dialysate Post-Pump
UF Pre-Pump
UF Post-Pump
Blood Flow Rate vs. Pump Pressure:Baxter Colleague 3
**
*
++
+
(* = P <0.05 vs. Blood Flow Rate 100)(+ = P <0.05 vs. Blood Flow Rate 100)
Effect of Total Flow on CRRT Pump Pressures-Trilogy
0
20
40
60
80
100
0 200 400 600 800 1000 1200
Total Flow Rate(ml/min)
Dialysate Pre-Pump
Dialysate Post-Pump
UF Pre-Pump
UF Post-Pump
Total Dialysate + Ultrafiltrate Flow Ratevs. Pump Pressure: Medex Trilogy
**
**
(* = P < 0.05 vs. Total Flow Rate 0)(+ = P < 0.05 vs. Total Flow Rate 0)
+
Effect of Total Flow on CRRT Pump Pressures-Colleague 3
0
20
40
60
80
100
0 200 400 600 800 1000 1200
Total Flow Rate(ml/min)
Dialysate Pre-Pump
Dialysate Post-Pump
UF Pre-Pump
UF Post-Pump
Total Dialysate + Ultrafiltrate Flow Ratevs. Pump Pressure: Baxter Colleague 3
**
**
(* = P < 0.05vs. Total Flow Rate 0)
* *
Effect of Net UF Flow on CRRT Pump Pressures-Trilogy
0
20
40
60
80
100
120
140
0 50 100 150 200 250 300 350
Net Flow Rate(ml/min)
Dialysate Pre-Pump
Dialysate Post-Pump
UF Pre-Pump
UF Post-Pump
Net Ultrafiltrate Flow Ratevs. Pump Pressure: Medex Trilogy
****
(* = P < 0.05vs. Net Flow Rate 0)
* *
* **
Effect of Net UF Flow on CRRT Pump Pressures-Colleague 3
0
20
40
60
80
100
120
140
0 50 100 150 200 250 300 350
Net Flow Rate(ml/min)
Dialysate Pre-Pump
Dialysate Post-Pump
UF Pre-Pump
UF Post-Pump
Net Ultrafiltrate Flow Ratevs. Pump Pressure: Baxter Colleague 3
(* = P < 0.05 vs. Net Flow Rate 0)
* *
Results of In Vitro Studies
• Direct correlation between blood flow rate and:D Post-Pump Pressures (80% increase)UF Pre-Pump Pressures (52% increase)
• Correlations with total D + UF flow rate:Direct - UF Post-Pump Pressures (0-15 mm Hg) Inverse - D Pre-Pump Pressures (75-69 mm Hg)
• Correlations with net UF flow rate:Direct - UF Post-Pump Pressures (14-21 mm Hg) Inverse - D Post-Pump Pressures (68-45 mm Hg) Inverse - UF Pre-Pump Pressures (93-71 mm Hg)
Summary
• Pump accuracy variable among available IV pumps for CRRTAll still within industry standards at all flow rates
• All 3 pumps consistently resulted in underinfusion of fluid when used for dialysate (inflow)
• 2 of 3 pumps consistently resulted in excess fluid removal when used for ultrafiltrate (outflow)
• Pump errors are generally additive and result in unanticipated fluid losses (x = -5.2%)
Summary
• Unanticipated fluid losses during CRRT with available IV pumps are clinically significant (>1000 ml/24 hr)
• Clinically relevant changes in blood flow, total dialysate + ultrafiltrate, and net ultrafiltrate flow rates do result in significant alterations in IV pump pressure loads
• Impact of IV pump pressure load changes on pump performance currently being analyzed