This document discusses techniques for hemofiltration, blood conservation, and ultrafiltration during cardiopulmonary bypass. It describes: 1. Ultrafiltration and hemofiltration remove fluid and solutes from the bloodstream using semipermeable membranes to create concentration gradients. This can effectively remove edema and concentrate blood. 2. Modified ultrafiltration after bypass can immediately increase hematocrit, decrease right atrial pressure, and improve organ function and hemostasis. 3. Blood conservation techniques during cardiac surgery aim to reduce blood transfusion needs through measures like autologous donation, cell savers to retrieve shed blood, and minimizing priming volume.

1. Hemo filtration &
Blood conservation
technique
MANU JACOB
PERFUSIONIST
KMCT MCH
CALICUT

2. Concept of ultrafiltration
• To remove large volume of fluid from the
intravascular space in short duration
• Movement of water across a membrane due to
hydrostatic pressure gradient
• No dialysate required
• The fluid removed is called ultrafiltrate

3. Concept of dialysis
• It is a process in which blood is separated from
crystalloid solution by a semipermiable membrane
• A solute concentration gradient exsists b/w the blood
and dialysate

4. purpose
• Effective removal of edema fluid in over hydrarted
patients.
• In renal impairment.
• To concentrate hemodiluted blood.
• Blood conservation through preservation of platelets
and coagulation factors.
• Reduced post cpb inflamatory response.

5. Purpose contd.,
• Decreases complement activation and inflamatory
response.
• Improves pulmonary cardiac and neurologic function
• Moderates temperature elevations by removing
circulating pyrogens

6. Advantages of Hemofiltration
• Advantages of Hemofiltration:
• Removal of water.
• -Reduces tissue edema .
• - Increase Hct
• Increase Coagulation factors
• Removal of inflammatory mediators
• -(tissue necrosis factor,C3a,
interleukins –1 & 6 etc)
• Removal of any solutes < Cut off
value(60,000daltons)

7. Physiologic principles
• “Selective seperation of plasma water and low
molecular weight solutes from intravascular cellular
components and plasma protiens of blood using a
semipermiable membrane filter”

8. The Equation
• TMP = Pa + Pv/2 + Ps
• Tmp = Transmembrane pressure
• Pa = inlet blood pressure
• Pv = outlet blood pressure
• Ps = Suction pressure

9. Efficacy of ultrafilter
• Efficacy is determined by the equation
Qf = Uc X TMP _ IP
Qf – ablity to remove fluid
Uc- Ultrafiltration coefficent
Ip- Protien oncotic pressure

10. Factors affecting the
filtration:
• Factors affecting the filtration:
• Diameter of pores(10-35A)
• Number of pores
• Thickness of membrane
• Viscocity of blood, Hct, Protein levels
• Temperature
• Absolute ultration can be increased by:
• Increasing inlet pressure
• Clamping outlet partially
• Increasing filtrate side negative pressure
• Increasing blood flow

11. Effect of CUF with temperature & Hct

12. RATE OF FILTRATION

13. Efficacy contd.,
• The efficiency of the ultrafiltration will depend on
• HB concentration
• Temperature
• Rate of blood flow
• Serum protien concentration
• Membrane structure

14. Sieving co-efficient
• The efficiency of an ultrafiltration device to remove a
soluble molecule is called sieving coefficient and is
directly related to molecular size.
• The larger the molecular size the less eficient the
ultrafiltration device

15. Table
SubstanceSubstance MolecularMolecular
weightweight
SievingSieving
coefficientcoefficient
Na,Na,
K+,urea,creatinK+,urea,creatin
glucoseglucose
AroundAround
10,000daltons10,000daltons
11
Albumin,Hb,fibriAlbumin,Hb,fibri
nogen,rbc,wbcnogen,rbc,wbc
and plateletsand platelets
69,000daltons,669,000daltons,6
8,000 and8,000 and
341,000daltons341,000daltons
Nearly zeroNearly zero
HeparinHeparin 6,000-6,000-
25,000daltons25,000daltons
.5.5

16. Sieving co-efficient

17. Effect of ultrafiltration on drugs
• Heparin
• Decreases serum level of anesthetic agents
• Decreases aprotinin level
• Removes pharmacological agents with low molecular
weight

18. Technical Aspects
• Hollow fiber construction
• Materials:-
1. Polysulfone
2. Polyacrylonitrite
3. Cellulose acetate
• Pore size 180 to 200micrometers in dia
• Pores of the microporous membrane 5 to 10 nm
• Placement in extracorporeal circuit

19. Types of ultrafiltration
1.Conventional ultrafiltration(cuf)
2.Modified ultrafiltration(muf)
3.Zero balance ultrafiltration

20. CUF

21. CUF

22. Indications
1. Free water removal
2. Compromised renal function
3. Preservation of hemostasis
4. To reduce alterations of immune function

23. Contraindications
• No absolute contraindications.
• Theoritically increased rbc damage
• Extra cost

24. Organ effects
• Reduction in PVR, Lung water, Increase in Lung
compliance
• Reduction in HR, Increase Systolic Pressure,
• Inrease in CI
• Better renal function(secondary to removal of mediators)
• Reduced cerebral edema
• Increased cerebral oxygen delivery

25. MUF advantages
• Immediate responses:
• HCt Increase (by 60-70%)
• RA Decrease (by 50-60%)
• LA Decrease (by 25-35%)
• Tidal Volume Increase (by 20—40%)
• P A Decrease (by 30-50%)
• Contractility Improved
• Haemostasis Improved
• Heart size Reduced (to be correlated)
• Blood Sugar Levels Decreased(40-50%)
• Blood transfusion No R C required

26. MUF diaadvantages
• Disadvantages:
• Time Delay
• Temperature drift if Heat Exchanger is not
available
• Homodynamic instability in the initial period
• Air embolism
• -Proper snugger around Aortic Cannula
• -Isolate Oxygenator from MUF circuit
• Disposable Cost

27. MUF circuit without cpg

28. MUF without cpg

29. Hemodialysis during CPB
• Membrane material is similar to ultrafilter
• The difference is dialysate is passed through the
nonblood side of membrane
• Removes diffusible solutes based on concentration
gradient by the dialysate soln
• Water and solutes are removed by convection

30. Circuit design for dialysis in
CPB
• Hemodialysis machine not used in CPB
• Dialyser positioned parallel to the ECC
• Dialysate solution - .9%NS
• Dialysate can be configured so as to achieve efficient
diffusion rate
• Dialysate flow should be 3 times the blood flow

31. Advantages
• Hemodialysis is effective in removing potassium and
small molecular wt solutes
• Small molecules like urea and electrolytes can be
removed.
• Hemofiltration is better for middle molecules .
(because of convection rather than diffusion)

32. Blood conservation Techniques
• Cardiac surgery has propensity of excess blood usage
due to
• Extensive intervention involving major vascular
structures
• Destruction of rbc and coagulation factors during
CPB resulting in increased need of blood
• Extracorporeal circuit

33. Blood conservation stratagies
1. Retropriming and reduction in priming volume
2. Autologus donation
3. Scavenging of shed blood(cell savers)

34. Cell saver outline

35. Retroprime