Priming Solutions

4 Major Factors to consider when selecting Priming Solution?

- Osmolarity
- Electrolytes
- Dilution
- Morbidity

What % is water of body weight in adults

• Males = 65% water

• Females = 55% water

What are the Two Major Compartments for Body Water Distribution?

- Intracellular Fluid (ICF) (40% of body weight) (2/3 of body water)
- Extracellular Fluid (ECF) (20% of body weight) (1/3 of body water)

What two subdivision is the Extracellular Fluid (ECF) divided into?

- Intravascular Fluid (IVF)
- Interstitial Fluid (ISF)

What are 3 three types of Concentration of Solutions?

- Moles/L or mmol/L
(Weight or volume per volume)

- mEq/L
(Charge per volume)

- mOsm/L
(Osmotic Activity per volume)

Osmolarity

Total concentration of all solutes per liter of solution

(Osmolarity (Osm/L) = Osmole / 1 L of solution

Osmole

Number of moles of solute that contributes to the osmotic pressure of a solution

Osmosis

movement of water through a semipermeable membrane from an area of Low solute to High solute Concentration

(Solvent follows Solute)

What does Tonicity mean?

The ability of a solution to cause a cell to gain or lose water

(Basically comparing the osmolarity of 2 solutions)

Hypertonic
Isotonic
Hypotonic

Osmotic Pressure

Minimum Pressure Applied to a solution to prevent Osmosis

Oncotic pressure

• Pressure created by the presence of large protein molecules which tend to retain fluids in the capillaries

  • Albumin

  • immunoglobulins

  • fibrinogen

What are the 5 main types of Priming Solutions?

- Crystalloids
- Colloids
- Blood and blood products
- Oxygen Carrying solutions
- Additives to the prime

Crystalloids

Contain electrolytes dissolved in water

• Na, K, Ca, Cl

• Can by Hypertonic, Hypotonic, Isotonic

• Both water and electrolytes will cross semi-permeable membrane into interstitial space and achieve equilibrium in ~2-3 hours

Hypotonic Crystalloid solutions

• A crystalloid soln that has a lower concentration of electrolytes than body plasma

• will cause fluid to leave vasculature for the interstitial & intracellular spaces

• may result in edema over time

Isotonic crystalloids

• A crystalloid soln that has an equal concentration of electrolytes as body plasma

• Will not cause any significant fluid shifts across cellular or vascular membranes

What is the major Osmotic Active substance?

Na+

Colloid solutions characteristics

• Contain large proteins that keep water in the vascular system

• Do not ionize in solution (remain uniformly distributed)

• Plasma volume expanders

• Remain in vascular compartment for long periods of time (~2-8 hrs)

What is the first thing we should watch when giving blood or drugs?

Blood pressure

(Because it can indicate is there is a reaction going on [Vasodilation])

Why do add Bicarbonate (HCO3) when giving prime, instead of putting it into the solutions directly when storing it?

It can precipitate out if stored on a shelf (IV bag)

What are two important things to look at on a Priming Solution bag?

- Expiration Date
- Caution/Use Label

What 4 main Blood Products do we give?

- Packed Red Blood Cells (PRBC's)
- Fresh Frozen Plasma (FFP)
- Platelets
- Cryoprecipitate

Why do we give Platelets at room temperature?

When colder it denatures them and makes them less effective for coagulation

What are the main Prime Additives?

• Heparin

• Mannitol

• Sodium Bicarbonate

• Corticosteroids

• Glucose

• Calcium (peds)

If we give Heparin and it is not working to anticoagulate, what drug can we give to help it?

Antithrombin III (ATIII)

(It is very expensive though)

What can be used as a temporary version of ATIII if it is not available?

Fresh Frozen Plasma (FFP)

What is a Normal Heparin Dose?

400 Units per kg

Example:
(60kg Patient x 400 = 24,000 Units)

(We have 10,000 units already in our prime but do not count it, just add the 24,000 to our prime now)

(Technically 34,000)

Why do we give Corticosteroids on CPB?

• To attenuate (lessen) the patients activation of inflammatory response

• 30 mg/kg in prime if used

Blood volume by weight

• males = 70 mL/kg

• females = 65 mL/kg

• infant = 75-100 mL/kg

What is PDHCT?

The hematocrit level after a patient has undergone fluid dilution

What is the PDHCT equation?

PDHCT = RBCV / TBV

RBCV = Hct x PBV

TBV = PBV + Prime vol + anest. vol - urine output - RAP/VAP

What are some ways to minimize hemodilution?

- Decrease Circuit Volumes
- Decrease tubing length
- Use an oxygenator with a smaller priming volume
- RAP
- VAP

Retrograde Autologous Prime (RAP)

• uses pt’s blood to displace some of the circuit prime vol into a collection bag

• flow is retrograde thru the arterial line/cannula

Venous Autologous Prime (VAP)

• Uses pt’s blood to displace some of the circuit prime vol into a collection bag

• Flow is antegrade thru the venous line/cannula

Osmalality

total concentration of all solutes per kg of solvent

osmolality = osmoles / 1 kg of solvent

Crystalloid soln examples

• Plasmalyte

• Normosol

• Isolyte

• Lactated Ringers

• 0.9% normal saline

• 5% dextrose in water (D5W)

Prime solns ideal characteristics

• Balanced electrolytes

• pH balanced

• Isotonic

Colloid solution examples

• 5% & 25% Albumin

• Dextran 40 (low MW) & Dextran 70 (high MW)

• 5% Plasma Protein Fraction (PPF)

• 6% hydroxyethyl starch (HES)

• Human Plasma (FFP)

Dextran warnings

• Potential coagulation problems

• anaphylactic rxns

• renal failure

• need to monitor glucose levels

6% HES warnings

• Renal dysfunction

• coagulopathies

• hypersensitivities

• ↑ mortality

Crystalloid ADVs

• - Low Molecular Weight ions

• - Readily cross capillary membranes

• - Short half life (30 minutes)

• -↓ plasma COP

• - No anaphylactic reaction (Just electrolytes and sugar water)

• - Cheap

• - Readily available and easy to store

Crystalloid DisADVs

• ↓ plasma COP

• risk of tissue edema

Colloid ADVs

• - Higher Molecular weight Substances

• - Do not readily cross capillary membranes

• - Longer Half Life (2-2.5 hours)

• - ↑ COP

• - Insignificant risk of Edema

Colloid DisADVs

• - Risk of Anaphylactic Reaction (Animal Proteins (Albumin))

• - Expensive

• - Less available in some settings

• ↑ COP

Potential ADVs of synthetic O2 carrying solns

• Readily available

• long shelf life

• do not require blood typing & cross matching

• free of infectious contamination

• does not cause immunosuppression

• relieve blood shortage problems

Potential alternatives to normal priming solns

• O2 carrying solutions

• Hgb based O2 carrying solns

Heparin

• Polysaccharide molecule

• binds to antithrombin III (ATIII)

  • inactivates coagulation enzymes

• 10,000 units in prime typically

Mannitol

• Sugar alcohol

• osmotic diuretic

• elevate blood plasma osmolarity

• Oxygen free radical scavenger

• can lower blood pressure

Antibiotics to reduce surgical site infection

• Cefazolin

  • 25 mg/kg

• Ampicillin

  • 50 mg/kg

• Gentamicin

  • 2 mg/kg

• Vancomycin

  • 10-15 mg/kg

Potential benefits of hemodilution

• ↓ blood viscosity

  • ↓capillary sludging

  • ↑ O2 delivery to tissues

• ↓ exposure to blood products

  • ↓ cerebral, pulmonary, & renal complications

Potential problems of hemodilution

• ↓ Hct

  • ↓O2 carrying capacity (↓ CaO2)

  • ↓ O2 delivery to tissues (↓ DO2)

• ↓ plasma protein concentration (↓COP)

  • fluid shift from plasma to interstitial spaces (possible edema)

Calculate PDHCT

• Female = 65 kg

• • Prime volume = 900 mL

• • Anesthesia volume = 1500 mL

• • Pre-CPB Hct = 32%

= 20.4%

Calculate PDHCT

• Oxygenator: 250mL

• • Arterial filter: 125mL

• • Venous reservoir: 150mL

• • Hemoconcentrator: 90mL

• • Circuit tubing: 6’ arterial, 6 ‘ Venous

• • Cardioplegia circuit: 280mL

• • Female = 65 kg

• • Prime volume = ?

• • Anesthesia volume = 1500 mL

• • Pre-CPB Hct = 32%

Prime vol = 1255 mL

PDHCT = 19.4%