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Pediatric CRRT: Ultrafiltration Control William E. Smoyer, M.D. Pediatric Nephrology University of Michigan.

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Presentation on theme: "Pediatric CRRT: Ultrafiltration Control William E. Smoyer, M.D. Pediatric Nephrology University of Michigan."— Presentation transcript:

1 Pediatric CRRT: Ultrafiltration Control William E. Smoyer, M.D. Pediatric Nephrology University of Michigan

2 Introduction Ultrafiltration control not a widely accepted concern for CRRT ä Often not regulated in adult ICUs ä No reports of significant volume imbalances Industry standards for pump error % 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, Roberts M et al. Int J Artif Organs. 15:99, 1992

3 CRRT Pump Accuracy Study Hypothesis: Unanticipated fluid losses with CVVHD are clinically significant and result from variable pressure loads on the pumps Study Design: ä 1) To prospectively analyze the accuracy of available IV pumps during CRRT in vivo ä 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

4 Methods Patients ä 4 infants and children requiring CRRT (CVVHD) CRRT Circuit ä Hemofilters: Renal Systems; Renaflo II HF 400 (SA 0.30 m 2 ) Hospal; Multiflow - 60 (SA 0.60 m 2 ) Minntech; Minifilter Plus (SA 0.07 m 2 ) ä Blood Flow: 4 cc/kg/min (Gambro AK 10) ä IV Pumps: Medex Trilogy / Alaris Gemini / Baxter Colleague 3

5 Methods In Vivo Data Collection ä Bags weighed on infant scale accurate to +0.5 ml (g) ä Sequential 1 hour measurements of: Set vs. Measured dialysate inflow Set vs. Measured ultrafiltrate outflow In Vivo Data Analysis (1049 total pump-hours) ä Analysis of absolute hourly error for each pump ä Analysis of mean % error for each pump ä Comparison of each pumps mean % error: At variable pump flow rates During use for dialysate (inflow) vs. ultrafiltrate (outflow)

6 CRRT Pump Accuracy-Trilogy

7 CRRT Pump Accuracy-Gemini

8 CRRT Pump Accuracy-Colleague 3

9 CRRT Pump Accuracy-Combined

10 Results of In Vivo Studies Dialysate Pump Error (all pumps): ä Range: % ( ml/hr) ä Mean: -4.0% Ultrafiltrate Pump Error (all pumps): ä Range: % ( ml/hr) ä Mean: +0.9% Cumulative Pump Error (all pumps): ä Range: % ( ml/hr) ä Mean: -5.2%

11 Effect of Blood Flow on CRRT Pump Pressures-Trilogy

12 Effect of Blood Flow on CRRT Pump Pressures-Colleague 3

13 Effect of Total Flow on CRRT Pump Pressures-Trilogy

14 Effect of Total Flow on CRRT Pump Pressures-Colleague 3

15 Effect of Net UF Flow on CRRT Pump Pressures-Trilogy

16 Effect of Net UF Flow on CRRT Pump Pressures-Colleague 3

17 Results of In Vitro Studies Direct correlation between blood flow rate and: ä D Post-Pump Pressures (80% increase) ä UF Pre-Pump Pressures (52% increase) Correlations with total D + UF flow rate: ä Direct - UF Post-Pump Pressures (0-15 mm Hg) ä Inverse - D Pre-Pump Pressures (75-69 mm Hg) Correlations with net UF flow rate: ä Direct - UF Post-Pump Pressures (14-21 mm Hg) ä Inverse - D Post-Pump Pressures (68-45 mm Hg) ä Inverse - UF Pre-Pump Pressures (93-71 mm Hg)

18 Summary Pump accuracy variable among available IV pumps for CRRT ä All 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%)

19 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


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