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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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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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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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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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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