Exam 7 - Vent / Suction / Prime Flashcards

1
Q

Normal return to Ventricles

A
- Right: systemic venous return
              coronary sinus drainage
              \+/- small cardiac vein
- Left:  Bronchial circulation
- Both:  Thebesian veins
              Cardioplegia
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2
Q

Abnormal return to Ventricles

A
  • Right: LSVC
    Atrial/Ventricular septal defects
    -Left: PDA (bypass lungs)
    Systemic to PA shunt
    Anomalous systemic venous drainage to heart
    AI
    Atrial/ventricular septal defects
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3
Q

Bronchial circulation

A
  • nutrients to lungs
  • Normal: 1-3% CO
    - can be up to 10% if COPD / lung infection / lung inflammation
  • Bronchial veins empty to pulmonary veins then back to LA
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4
Q

Small cardiac vein

A
  • usually empties to coronary sinus but may also to:

- RA / middle cardiac vein / or may not be there

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5
Q

Thebesian Veins

A
  • Spongy veins in endocardium of heart
  • blood bleeds through these into all 4 chambers of heart
  • only minor blood return to heart
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6
Q

Antegrade Cardioplegia

A
  • Left coronary
    - drains into coronary sinus and RA
  • Right coronary
    - drains into RA via small cardiac vein
  • Some flow return to all chambers via thebesian veins
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7
Q

Retrograde Cardioplegia

A
  • Most empty into aortic root / L ventricle via left coronary ostia
  • not that good at protecting heart (not protecting R heart)
  • can’t do at same time as antegrade…heart will blow
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8
Q

LSVC

A
  • normally drains into coronary sinus (92%)
  • 0.3-0.5% of pop but 2-10% of patients w/ heart disease
  • Problem if opening right heart or bi-caval cannulation
  • Problem w/ retrograde cardioplegia
    • delivery up the LSVC and/or dilution of solution from return
  • Failure of L. Brachiocephalic vein to develop
  • Failure of L common cardinal vein to disappear
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9
Q

Blalock-Taussig Shunt

A
  • Right subclavian to Right PA
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10
Q

Waterston Shunt

A
  • Posterior ascending aorta to anterior R PA
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11
Q

AI

A
  • not a problem if heart is beating
    - X-clamp stops regurgitation from arterial cannula
  • can occur during cardioplegia delivery (low aortic root pressure)
  • can cause LV distension in fib or arrested heart
  • makes putting in balloon pump not worth it
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12
Q

Vent purpose

A
  • prevent ventricular distension
  • improve exposure
  • aid in myocardial protection
  • remove air
  • prevent pulmonary venous hypertension
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13
Q

Where to vent

A
  • Both R and L ventricles

- PA vent used if blood is coming back to RV

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14
Q

Myocardial protection

A
  • Keep heart empty
  • Decompression: reduces resting O2 use by reducing stretch
    40% of protection
  • Increased subendocardial perfusion: keeping LV empty is optimal for LV coronary perfusion
  • Prevent myocardial rewarming: 10% / remove systemic return keeps cool
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15
Q

Air removal

A
  • Venting removes air that got in after closure but before x-clamp removal
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16
Q

Venous cannulation and Return Concerns

A
  • must collect from: SVC / IVC / Coronary sinus
  • Bi-caval cannot collect from coronary sinus
  • Improper cannula placement
  • wrong cannula size
  • improper height gradient
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17
Q

Vent locations

A
  • Aortic root: can add cardioplegia line if want
  • Right Superior Pulmonary vein: can go into LA or LV
  • Main PA: can interfere with Swan catheter (rarely used)
  • Apex of LV (least common)
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18
Q

Mechanical drainage

A
  • roller pump
  • one way valve to prevent air backflow
  • OK to use high RPM w/ vacuum relief valve (prevent hickies)
  • Must use low RPM in no vacuum relief valve
    - best to monitor LA pressure (to prevent hickies)
  • just occlusive
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19
Q

Gravity drainage

A
  • Wye vent line into venous return line
  • vent line must be primed to prevent air lock
  • creates venturi effect
  • surgeon controls vent on and off
  • Can also use solo siphon drainage tubing
    • may not vent enough depending on venous return
20
Q

Cardiotomy / Pump Suction

A
  • Separate cardiotomy filter reduces microemboli
  • More coag factors / endotoxins / complements / Interleukins
  • Profound drop in arterial bp often seen when suction blood is infused into patient
  • just non-occlusive: don’t want to squish blood
  • might be better to use cell savers instead of suckers
    - reduction in post op bleeding
    - reduction in cerebral fat emboli and stroke rate (SCADs)
21
Q

Cell-Saver guidelines

A
  • 40-150 micron filter
  • vacuum should not exceed -120 mmHg
  • Anticoagulant drip must be used: heparin saline / CPD / Bivalirudin
  • Washed product returned through filter
  • Should be washed with at least 1000 mls of saline - clear effluent
  • washed product into separate reinfusion bag - less air
    ~bag labeled w/ patient name ID / exp time / volume / autologous note
  • never use pressure bag to speed reinfusion time
22
Q

Transfusion practices

A
  • product hematocrit > 40%
  • product K < 3.0 mEq/L
  • product free hemo [ ] < 100 mg/dL
  • product heparin [ ] < 0.5 units/ml
23
Q

Colloid

A
  • Mixture
  • Larger insoluble molecules
  • Blood
24
Q

Crystalloid

A
  • aqueous solution of mineral salts or other water soluble

- Normal saline

25
Q

Colloid osmotic pressure (oncotic pressure)

A
  • Protein [ ] that pulls fluid into capillary system
26
Q

Osmotic pressure

A
  • pressure needed to prevent inward flow of water across semi-permeable membrane
27
Q

History of prime

A
  • Used to be primed with fresh haparinized blood
  • now crystalloid is used
  • no simple consensus on what is best
28
Q

Crystalloid base prime

A
  • Dextrose, pH balanced crystalloids, Mannitol
  • mimic normal plasma electrolyte concentrations
  • Most lack oncotic activity (except Mannitol)
  • easy to handle / cheaper / no allergic reactions
  • improve post-op pulmonary and renal function
29
Q

Crystalloid solution examples

A
  • Plasmalyte
  • Normosol
  • 0.9% NS (overtime will become acidodic)
  • LR (added lactate-convert to bicarb IF liver works-good for acidosis)
  • D5 (with diff % NS)
30
Q

Colloid Primes

A
  • contain protein or starch
  • can maintain high colloid oncotic pressure and reduce edema
  • can increase incidence of allergy rxns and coag
31
Q

Colloid prime examples

A
  • albumin (most common)
  • dextrans
  • gelatins
  • hespan
32
Q

Hypertonic

A
  • Osmolarity > 350 mOsm/L
  • raise serum osmolarity…pulls fluid from cells
  • D10 is temporarily hypertonic
33
Q

Hypotonic

A
  • Osmolarity < 250 mOsm/L

- 0.45% NS and 0.25% NS

34
Q

Isotonic

A
  • 285-295 mOsm/L

- 0.9% NS

35
Q

Hydrostatic pressure

A
  • Pressure of intravascular fluid against wall of vessel

- higher at proximal end (oncotic higher at distal)

36
Q

1 L of H20 at 4C

A
  • 1 Kg

- this means for dilute aq solutions…osmolarity=osmolality

37
Q

Colloid Osmotic Pressure (COP)

A
  • Normally higher in capillaries due to proteins

- CPB hemodilution disrupts this balance

38
Q

Hemodilution considerations

A
  • decreases bypass related complications
    - or maybe it is fact that you are not giving blood?
  • affects the properties of drugs used in CPB
    - changes protein binding through dilution of plasma proteins
  • can cause edema (not good)
39
Q

Advantages of hemodilution

A
  • decrease blood viscosity
  • improve regional blood flow / oxygen delivery
  • decrease exposure to blood products
  • improved flow at lower perfusion pressures (lower shear stress)
    • especially at low temps
40
Q

Allowable hemodilution

A
  • most try to keep Hct below 30%
  • can get this with 1000-1500 mls of prime
  • big patients or high Hct may need more dilution while on pump
41
Q

Optimal fluid for priming

A
  • not known
  • most blood free
  • albumin can increase colloid oncotic pressure while attenuating the platelet lowering effects of CPB
42
Q

Basic Prime ingredients for Adults

A
  • Normosol/Plasmalyte
  • Hetastarch (JeWtns) / Albumin
  • Antibiotic
  • NaHCO3 (makes more alkaline)
  • Mannitol
  • Heparin 10 K units
43
Q

Basic Prime ingredients for Peds

A
  • Normosol
  • 25% albumin (pacification of tubing) (large molecule)
  • Antibiotic
  • Solumedrol - corticosteroid
  • NaHCO3
  • Heparin 100 units
  • Mannitol
  • CaCl
  • PRBC
44
Q

NaHCO3 calculation for PRBC

A

= 0.3 x kg x BE

BE should be 0…if acidic…BE is negative

45
Q

Mannitol

A
  • Osmotic diuretic
  • elevates osmolarity rapidly
  • dilutes a lot more than just crystalloid
  • oxygen radical scavenger?
  • 0.25 g/kg in prime
  • can drop BP more than just CPB
  • lose reservoir volume
  • will always end up giving more blood….bad
46
Q

CaCl normal

A
  • 0.7-0.8 mM/L
47
Q

Glucose

A
  • 75 to 115