This document discusses the history and techniques of priming fluids and hemodilution in cardiopulmonary bypass. It notes that early surgeons used whole blood for priming, while later techniques incorporated saline and dextrose solutions to enable hemodilution. Hemodilution provides benefits like reduced blood viscosity and improved oxygen delivery, but can cause issues like decreased oxygen carrying capacity if taken to an extreme. The document examines various priming fluid options and how hemodilution affects viscosity, oxygen transport, and hematocrit. Overall, priming fluids and controlled hemodilution have advanced CPB by enabling adequate organ perfusion in difficult circumstances and reducing complications while conserving blood.

1. Priming Fluids and
hemodilution
Manu Jacob
Perfusionist
KMCT MCH
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2. HISTORICAL PERSPECTIVES
Surgeon Year Priming Soln Technique
Gibbons 1953 Whole blood High Flow
Kirklin 1956 Whole blood High Flow
Lillehei 1955 Whole blood Low Flow
Panico 1959 Saline Haemodilution
Long 1961 Dextran and 5%
Dextrose
Haemodilution and
hypothermia
Dewall & Lillehei 1962 5% Dextrose Haemodilution and
hypothermia
Cooley 1962 5% Dextrose Haemodilution and
normothermia
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3. Prime
 To replace the air in the circuit with fluid
or blood.
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4. Why do we need prime ?
 To fill the circuit
 To check the circuit for leaks or damage
 To test the pump and circuit
 Priming with fluid reduces the blood
dependance.
 Priming fluid causes hemodilution.
 Hemodilution can be beneficial/harmfull.
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5. Necessity to Use Haemodilution
 Homologous Blood Syndrome
 Scarcity and cost of blood
 Oxygenators were inefficient.
Haemodilution increased their efficiency
 To reduce the harmful physiological effect
of blood going through the pump
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6. Advantages of hemodilution
 Decreases blood viscosity
 Improves regional blood flow
 Improved oxygen delivery of tissues.
 Decreased exposure to blood products.
 Improved blood flow at lower perfusion
pressures during hypothermia.
 Decreases bypass related
complications(neurologic,renal and
pulmonary)
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7. Disadvantages of hemodilution
 Extreme hemodilution can cause
1. Decrease in oxygen carrying capacity
2. Tissue edema in various organs
3. Reduces neuro congnitive outcomes
4. Increases the distance between capillaries and
tissues causing tissue necrosis and cell damage
5. Can cause mortality and morbidity
6. Increases lung fluids after CPB
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8. EFFECTS OF HAEMODILUTION
1. Change in Viscosity
Because Flow  Perfusion Pressure
Total Peripheral Resistance
And Total Peripheral Resistance = Vascular resistance x
Viscosity
Then Flow  Perfusion Pressure
Vascular resistance x Viscosity
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9. 13/02/2019 9
RELATIONSHIP OF VISCOSITY
TO PRESSURE DROP

10. 13/02/2019 10
EFFECTS OF HAEMODILUTION
2. Effect on Oxygen Transport

11. EFFECTS OF HAEMODILUTION
3. Effect on Haematocrit
Predicted Hct on bypass =
Patients blood volume before CPB x pre CPB Hct
Patients blood volume before CPB + CPB prime
Where the adult patients blood volume can be
estimated at 70 mls per kg wt and the child at 80
mls per kg.
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12. Basic definition of solution
 A homogenous mixture of two or more
substance called solvents and solutes.
 The substances dissolved in the solvent
are called solutes.
 Based on the concentration of solutes a
solution becomes iso, hyper or hypotonic.
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13. Classification of priming fluids
 Crystalloids : fluids with smaller solutes
and lesser atomic weights. Remains in the
circulation for smaller time ( 15 mts) eg:
Ringers soln, Dextrose etc
 Colloids : Fluids with bigger solutes and
greater atomic weight.colloids contain
larger They help in the preservation of
oncotic pressure. Eg : Hemacell, Albumin
etc
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14. Most commonly used primes
 Balanced Salt solutions
 Colloids (Hestril, albumin, plasma &
blood)
 Mannitol
 Heparin
 Bicorbonate as buffer
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15. Tonicity
 ISOTONIC : A solution that has the same
concentration as the cell. There is no
effect on the cell
 HYPERTONIC :A solution more
concentrated than the cell. So osmosis
occurs water moves out of cell and cell
shrinks
 HYPOTONIC : A solution less concentrated
than cell. water moves into cell.(swells)
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16. Primary Priming Fluid
Our Survey Hett and Smith
Hartmanns Soln 80% 71%
Ringers Soln 10% 13%
Plasmalyte 7% 7%
Colloid 3% 0
Saline 0 9%
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17. Additional Fluids
Our Survey Hett and Smith
Gelatin 45% 44%
Starch 12% 0
Albumin 6% 0
Dextrose Saline 0 2%
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18. Additives
Our Survey Hett and Smith
None 0 8%
Heparin 100% 89%
Mannitol 81% 37%
Bicarbonate 19% 26%
Potassium N/A 10%
Magnesium N/A 3%
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19. CRYSTALLOID SOLUTIONS
Hartmanns Ringers Plasmalyte 148
Sodium 131 147 140
Potassium 5 4 5
Calcium 2 2 -
Magnesium - - 1.5
Chloride 111 155 98
Lactate 29 - -
Gluconate - - 23
Glucose - - 5%
Acetate - - 2713/02/2019 19

20. Crystalloid solutions
 Most commonly used prime.
 Lot of institutional variations
 Similar electrolyte-to-plasma content
 Similar osmolarity.
 Degree of hemodilution to be predicted
with pt wt and Hct.
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21. Colloidal primes
 Hemodilution causes decrease in the
plasma collidal oncotic pressure
 This is due to dilution of circulating
plasma proteins.
 The addition of colloidal primes solves the
issue.
 Colloidal prime stays longer time in
circulation
 Cost and availability is a problem
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22. PLASMA VOLUME EXPANDERS
ALBUMIN GELOFUSINE HAEMACCEL PENTASPAN
SOURCE Naturally
occurring
Bovine
Collagen
Bovine
Collagen
Starch
Polymer
HALF LIFE 15 hours 2 ½ hours 2 ½ hours 4 hours
ELIMINATION Faecal Renal and
Faecal
Renal and
Faecal
Faecal
FREQUENCY
ADVERSE
EFFECTS
0.014 0.115 0.115 N/A
Hespan
0.085
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23. ALBUMIN
- Costly
- Disease Transmission
+ Coats surfaces
Reduced incidence of raised
transoxygenator pressure gradient
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24. COLLAGENS
- Anaphylaxis
- Haemaccel contains Calcium
+ Free radical scavenger
+ Cheap
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25. PENTASPAN
- ? Incorporated in clot formation
- ? Coagulopathies
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26. DEXTROSE
 Increases cerebral damage upon reperfusion
 However cerebral damage on bypass is due
to emboli therefore there is no reperfusion
 Dextrose can act as an osmotic agent
 Complications associated with
hyperglycemia have led to its withdrawal.
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27. MANNITOL
 Increases osmotic pressure and thus
reduces the onset of oedema
 Is an osmotic diuretic
 Is a free radical scavenger
 May help protect the kidneys from the
ischaemic insult of bypass
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28. Experimental priming solutions
 Blood substitues
1. Perflurocarbons
2. Cross-linked Hb
3. Polymerized Hb
4. Conjugated Hb
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29. Contd.,
 They can carry dissolved Oxygen
 They have ability to permit oxygen
delivery in anemic conditions
 Inslouble in blood (must be emulsified)
 Chemically inert substance
 Oxygen sloubility is linear
 They can release O2 irrespective of Ph
and temp
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30. Draw backs
 Unexpected safety concerns
 Unanticipated physiologic effects like
vasoconstriction etc.
 Clinical trials suspended in US
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31. Allowable hemodilution
 Large institutional variations in
“acceptable hemodilution”.
 Most centers try to achieve a hematocrit
below 30 % during CPB.
 Lower hct below 25% preferred if temp is
below 25 deg c.
 For adults hct b/w 22 to 25% is
acceptable.
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32. Assessing adequecy of perfusion
with hemodilution
 Perfusion pressure decreases with CPB.
 Hemodilution results in uncoupling of the
relation b/w perfuion pressure and blood
flow.
 Adequecy of perfusion must be assessed
by means other than BP.
 Flow rates should me modified according
to age,wt and temperature.
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33. Goals of prime in CPB
 To reduce the hemodilution as much as
possible
 To minimize the exposure of blood to
foreign surface
 To reduce the prime to as minimum as
possible
 To preserve the blood components
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34. Commonly used prime
Adult Paediatric
 Ringer lactate
 Heastril or
Gelofusane
 Mannitol (2ogms)
 Bicorbonate (Buffer)
 Heparin
(25mg/500ml)
 Whole blood or PRC
 FFP or Albumin(Oncotic
pressure to be maintained
at 15 mmhg)
 RL
 Bicorbonate (10ml)
 Heparin (25mg)
 Mannitol (.3 to.5gm/kg)
 Steroids
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35. Summary
 Reprsents singnificant avancement in CPB
technique.
 Permits maintenance of organ perfusion
under inadequate circumstances.
 Hemodilution has decreased
complications.
 Has helped in blood conservation.
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