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Hemoconcentration Hemofiltration Diafiltration Ultrafiltration CAVH CAVH D Hemofiltration Diafiltration Ultrafiltration CAVH CAVH D.

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Presentation on theme: "Hemoconcentration Hemofiltration Diafiltration Ultrafiltration CAVH CAVH D Hemofiltration Diafiltration Ultrafiltration CAVH CAVH D."— Presentation transcript:

1 Hemoconcentration Hemofiltration Diafiltration Ultrafiltration CAVH CAVH D Hemofiltration Diafiltration Ultrafiltration CAVH CAVH D

2 Hemofiltration Structure and Function F Glorified sieve FMolecules move across according to size (molecular wt.) FPlasma binding FTransmembrane pressure (TMP) F Glorified sieve FMolecules move across according to size (molecular wt.) FPlasma binding FTransmembrane pressure (TMP)

3 Hemofilters vs Dialysis FDialysis FSemipermeable membrane FConcentration gradient (osmosis) FConductive exchange of solutes FDialysate FSome convective force FDialysis FSemipermeable membrane FConcentration gradient (osmosis) FConductive exchange of solutes FDialysate FSome convective force

4 Molecular Clearance Dialysis Vs. Hemofiltration

5 Conventional Dialysis on ECMO FConventional Dialysis on ECMO is performed by accessing the circuit by stopcocks, taking blood from the arterial side of the circuit and returning it to the venous side or into a venous access line in the patient. FDialysis Service controls solute and fluid removal rates. FDialysis blood flow rates vary with size of patient and access. FConventional Dialysis on ECMO is performed by accessing the circuit by stopcocks, taking blood from the arterial side of the circuit and returning it to the venous side or into a venous access line in the patient. FDialysis Service controls solute and fluid removal rates. FDialysis blood flow rates vary with size of patient and access.

6 Hemofiltration Rate FBlood Flow FTMP = (P in + P out)/2 + vacuum on HF side, ex ( )/2 =110+(-75) = 185 mmHg FHematocrit FProtein concentration FResists fluid removal FBlood Viscosity FTemperature FBlood Flow FTMP = (P in + P out)/2 + vacuum on HF side, ex ( )/2 =110+(-75) = 185 mmHg FHematocrit FProtein concentration FResists fluid removal FBlood Viscosity FTemperature

7 Hemofiltration Rates Vs Blood Flow

8 Minifilter for ECMO F10 cm plastic tube FContains 25 Polysulfone hollow fiber (exchange membrane) FPrimes with 6 ml. (150cm2) FTMP 500 mmHg FBlood flow 500ml/min F10 cm plastic tube FContains 25 Polysulfone hollow fiber (exchange membrane) FPrimes with 6 ml. (150cm2) FTMP 500 mmHg FBlood flow 500ml/min

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11 Molecular Cut Off FDevice acts as a sieve FSolutes (molecules) dissolved in plasma are either retained or removed according to their size (molecular Wt. MW) FMW cut off 50,000 daltons FElectrolytes daltons FTherapeutic drugs 6, ,0000 daltons FNote - Dalton is unit of atomic Wt. 1Da = 1.66X FDevice acts as a sieve FSolutes (molecules) dissolved in plasma are either retained or removed according to their size (molecular Wt. MW) FMW cut off 50,000 daltons FElectrolytes daltons FTherapeutic drugs 6, ,0000 daltons FNote - Dalton is unit of atomic Wt. 1Da = 1.66X10 -24

12 Solute Clearance FSolutes in hemofiltrate are in the same concentration as the pts. Blood (if below the MW cut off) FThe amount removed is equal to the hemofiltration rate time the concentration of solute in question in the filtrate FAmount removed = (Concentration in filtrate) X (HR) FSolutes in hemofiltrate are in the same concentration as the pts. Blood (if below the MW cut off) FThe amount removed is equal to the hemofiltration rate time the concentration of solute in question in the filtrate FAmount removed = (Concentration in filtrate) X (HR)

13 Solute Clearance FIf large amounts of volume are removed with Hemofiltration, the actual amount of a given solute removed from a baby may be substantial

14 Solute Clearance FWhile the concentration of a solute in the HF may not be known, its concentration in the blood is routinely measured. F Ex. Sodium. 134 mEq/l FIf the MW is below the cut off of the fiber the concentration in the HF is essentially the same as the blood. Then: amount removed = (Conc.in blood) X (HF Rate) FWhile the concentration of a solute in the HF may not be known, its concentration in the blood is routinely measured. F Ex. Sodium. 134 mEq/l FIf the MW is below the cut off of the fiber the concentration in the HF is essentially the same as the blood. Then: amount removed = (Conc.in blood) X (HF Rate)

15 Sieving Coefficient FSC - The ratio of the amount of a given solute in the UF to that amount in the Blood. FEx 1. Sodium - amount in UF is 135 mEq/L and amount in the blood is 135 mEq/L the Sieving Coef. is 1.0. FEx 2. Albumin Serum = 5 gm/dl Blood Albumin UF = 0 gm/dl SC = ? FOther large molecules: F Total Bilirubin , erythromycin- 0.37, calcium FSC - The ratio of the amount of a given solute in the UF to that amount in the Blood. FEx 1. Sodium - amount in UF is 135 mEq/L and amount in the blood is 135 mEq/L the Sieving Coef. is 1.0. FEx 2. Albumin Serum = 5 gm/dl Blood Albumin UF = 0 gm/dl SC = ? FOther large molecules: F Total Bilirubin , erythromycin- 0.37, calcium

16 Sieving Coefficients for Selected Molecules

17 Sieving Coefficient & Protein Binding FCalculation of Solute clearance is complicated if molecule is protein bound. Monitoring of medication blood level is advised when aggressive HF is used. FProtein binding data is available for many medication used during ECMO. FCalculation of Solute clearance is complicated if molecule is protein bound. Monitoring of medication blood level is advised when aggressive HF is used. FProtein binding data is available for many medication used during ECMO.

18 Calculating Solute Clearance FIt turns out to be easier to calculate the amount of a substance being removed if you know its Sieving Coefficient using: FAmount lost = (Conc. In blood) X (SC) X (HR) FIt turns out to be easier to calculate the amount of a substance being removed if you know its Sieving Coefficient using: FAmount lost = (Conc. In blood) X (SC) X (HR)

19 Dialysis With Hemofiltration FDialysate solution may be used on the Hemofiltrate side of the cartridge to the remove solutes by osmotic gradients (conduction) and filtration(convection). Concentration of molecules in Dialysate control removal of various solutes from the blood. FEx. If Potassium is high in blood Dialysate will be low in Potassium the rest of the molecules will be balanced. FDialysate solution may be used on the Hemofiltrate side of the cartridge to the remove solutes by osmotic gradients (conduction) and filtration(convection). Concentration of molecules in Dialysate control removal of various solutes from the blood. FEx. If Potassium is high in blood Dialysate will be low in Potassium the rest of the molecules will be balanced.


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