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CV Perfusion Tech I > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q

Colloid

A

a substance microscopically dispersed evenly throughout another substance. Colloids contain larger insoluble molecules, such as gelatin or albumin. Blood is a colloid; mixture of two different phases of matter

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2
Q

Crystalloids

A

are aqueous solutions of mineral salts or other water-soluble molecules. Normal saline is a crystalloid; dissolved- no suspended

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3
Q

Osmolality

A

is a measure of the osmoles of solute per kilogram of solvent (osmol/kg or Osm/kg); per mass

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4
Q

Osmolarity

A

is the measure of solute concentration, defined as the number of osmoles (Osm) of solute per liter (L) of solution (osmol/L or Osm/L); per volume

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5
Q

Colloid Osmotic Pressure (Oncotic Pressure)

A

osmotic pressure exerted by proteins in blood plasma that pulls water into the circulatory system

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6
Q

Tonicity

A

the state of being hypertonic, hypotonic, and isotonic, is related to how much osmotic pressure is exerted on a membrane by a fluid; measure of the osmotic pressure gradient (defined by water potential of the 2 solutions) of two solutions separated by semipermeable membrane

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7
Q

Osmotic Pressure

A

is the pressure which needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane

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8
Q

What was the ECC primed with during early years?

A

“Fresh” heparinized homologous blood

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9
Q

Mannitol

A

aka. Osmitrol; oncotic agent, pulls fluid into blood stream; crystalloid

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10
Q

Crystalloid Prime Consists of….

A

Dextrose
pH balanced crystalloid fluids
mannitol (Osmitrol)

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11
Q

Advantages of crystalloid prime

A

Easy to handle during priming/de-airing
Cheaper
No anaphylactoid reactions

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12
Q

Crystalloid Solution Examples

A 
Plasmalyte
Normosol
0.9% Normal Saline
Lactated Ringers
D5 0.9% NS
D5 0.45%NS
D5 0.33% NS
D5 0.18% NS
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13
Q

PlasmaLyte Characteristics

A

Closely mimics human plasma
Electrolytes, osmolality & pH (similar to human)
Buffer capacity
Anions: Acetate, gluconate, lactate converted to bicarb, Co2 and water
No evidence that it is superior to other crystalloids

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14
Q

Plasmalyte Advantages

A

Volume/Electrolyte deficit correction

Addresses acidoses

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15
Q

PlasmaLyte Disadvantages

A 
Fluid overload
Edema with weight gein
Lung edema
Worsening of ICP
Magnesium: PVR, HR, worsen ischemia
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16
Q

Magnesium in Prime

A

Book says its a problem
Works in concert with calcium
Partially replenishes myocytes
No substantial effect on SVR based on research

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17
Q

Lactated Ringer’s

A

“Balanced” electrolyte solution with lactate added

Lactate converted into bicarbonate by a functioning liver into bicarbonate

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18
Q

Normal Saline (0.9% saline solution)

A

Must add bicarb because its so acidic
Matches blood tonicity
Just sodium chloride

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19
Q

Colloid Prime Characteristics

A

Contains protein or starch

Preserve high COP in the blood

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20
Q

Colloid Prime Advantages

A

Maintain COP and reduce tissue edema

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21
Q

Colloid Prime Disadvantages

A

Colloids associated with increased incidence of anaphylactoid reactions and clinical coagulopathy

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22
Q

Colloid Examples

A

Albumin
Dextrans
Gelatins
Hydroxyethyl starch (Hespan)

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23
Q

How is albumin sterilized?

A

Cold filtered

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24
Q

Hypertonic

A

Osmolarity > 350 mOsm/L
Solution cannot be “hypertonic” unless there is some indication of what it might be hypertonic to; greater amt of solbe more hypertonic

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25
Q

Is D10-10% Dextrose has what tonicity?

A

Hypertonic (temporarily)
Becomes hypotonic metabolizes sugar
Becomes water

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26
Q

Hypotonic

A

Osmolarity <250 mOsm/L
Distilled water is hypotonic to everything
Causes fluid to shift, lowers osmolarity, allows fluid to shift out of vessel into cells and interstitial space
Hypotonic fluids have the potential to cause sudden fluid shifts out of bloodvesels

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27
Q

Examples of Hypotonic Fluids

A

0.45% NS and 0.25% NS

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28
Q

Istonic

A

~285-295 mOsm/L

Freely move into and out of the intravascular compartments and increase circulating volume in the cells

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29
Q

Osmosis

A

Movement of water through a semipermeable membrane from an area of lower concentration of solute to higher concentration of solute

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30
Q

Osmotic Pressure

A

pressure which needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane

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31
Q

Oncotic Pressure

A

Created by the presence of large protein molecules such as albumin (55%) Immunoglobulins (38%) Fibrinogen (7%) and other regulatory and clotting factors tend to retain fluid in the capillaries
*Note: oncotic pressure is a type of osmotic pressure

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32
Q

Hydrostatic Pressure

A

pressure of the intravascular fluid against hte wall of the vein

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33
Q

How to convert L to kg?

A

1 Liter of H20 at 4 degrees C = 1 kg (2.205 lbs)

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34
Q

Advantages of Hemodilution

A

Decreased blood viscosity
Improved regional blood flow
Improved oxygen delivery to tissues
Decreased exposure to homologous blood products
improved blood flow at lower perfusion pressure (lower shear stress), especially during hypothermic perfusion

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35
Q

How much do you hemodilute?

A

Most centers try to achieve hematocrits below 30% during CPB.

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36
Q

What’s the normal priming volume range?

A

1000-1500 mL

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37
Q

Advantage of Albumin in Prime

A

Increases COP white at the same time (at least temporarily) attenuating the platelet-lowering effects of CPB

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38
Q

Basic Prime Constituents: Adults

A 
Normosol/PlasmaLyte
Hetastarch/Albumin
Antibiotic
NaHCO3
Mannitol
Heparin 10k units
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39
Q

Basic Prime Constituents: Pediatrics

A 
Normosol
25% Albumin
Antibiotic
Solumedrol
NaHCO3
Heparin 100 units
Mannitol
CaCl
PRBCs
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40
Q

25% Albumin

A 
Large molecule
Aids pacificiation of tubing
Elevates COP and serum osmolarity
Good osmotic "Pull" from tissues (1.3:1)
A Jehovah's Witness "no-no"
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41
Q

Pacification

A

Foreign surface pacification may significantly reduce the detrimental effects of the CPB circuit
*Without albumin, pacification will lead to low circulating proteins
To date, albumin is the only intervention consistently shown to be beneficial

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42
Q

What two constraints does siphonage place on venous drainage?

A
  1. venous reservoir must be below the level of the patient

2. lines must be full of blood (or fluid) or an air lock can occur and disrupt the effect

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43
Q

What influences CVP?

A

Intravascular Volume

Venous compliance

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44
Q

What influences venous compliance?

A

Medications
Sympathetic Tone
Anesthesia

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45
Q

Solutions to Chattering/Fluttering/Chugging

A

Partially occlude clamp on venous line

Increase the systemic blood flow

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46
Q

What is the ultimate limit to venous flow?

A

Amount of blood returning to the great veins from the body

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47
Q

Newton’s Law of Universal Gravitaiton

A

F=G (m1m2/r^2)

F=ma

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48
Q

How to calculate mass

A

volume x density

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49
Q

How to calculate weight

A

mass x gravity

50
Q

What is the constant for gravity

A

9.8 m/sec^2

51
Q

What is the density of water

A

1 @ 37 degrees C

52
Q

Principle of transmission of fluid-pressure

A

pressure exerted in a confined incompressible fluid is transmitted equally in all directions throughout the fluid so pressure variations remain the same

53
Q

Pascal’s Law

A

1mmHg for every 13.6 mm heigh
Potential energy to do work

P=pgh

54
Q

What is the normal siphon gradient?

A

30 to 40 mmHg

55
Q

What three factors affect the siphon gradient?

A

CVP
Cannula Resistance
Height (to end of venous inlet tube)

56
Q

Why use augmented venous return (AVR)?

A
  • smaller diameter cannula and venous line (minimal volume)
  • Long, narrow cannula (peripheral access)
  • generate venous return using smaller heigh differential, smaller diameter cannula, smaller diameter venous line, no fluid in venous line
  • Allow minimally invasive surgery
57
Q

Methods of Augementation

A

VAVR
KAVR
Modified Roller Pump

58
Q

Where do you monitor pressure in augmented return?

A

10 cm before pump inlet OR within hard-shell reservoir

59
Q

Max negative pressure in augmented return

A

-60 to -100 mmHg

60
Q

What could happen if the pump head is not occlusive?

A

Could pull retrograde

61
Q

Why would you want shunt around roller pump to be partially occluded?

A

Prevent build-up of excessive negative pressure

62
Q

Relief valve pressure limits

A 
Low positive (+15 mmHg)
High negative (-150 mmHg)
63
Q

Augmented Venous Return complications

A

Hemolysis
Decreased flow
Damage to vascular structures
Air aspiration
Over-pressurization of hard-shell venous reservoir (too much positive pressure)
Under-pressurization of hard-shell venous reservoir (too much negative pressure)
Imbalance between venous and arterial flows

64
Q

When do we use AVR?

A 
Minimally invasive surgeries
Femoral venous cannulation
unprimed venous lines (w.o VAP)
small heigh differential
smaller prime circuits (3/8'' venous)
pediatrics
possibly all cases
65
Q

Calculating Effective Negative Pressure Gradient

A

Effective negative pressure gradient = negative pressure (VAVR) + Gravity Drainage

Effective negative pressure = Negative pressure (KAVR) + Gravity drainage

66
Q

Range from the regulator in VAVR

A

-20 to -80 mmHg Range from regulator

67
Q

Because pressurization is a risk in CPB and VAVR, what should you set the alarm to?

A

+10

68
Q

In KAVR, what RPMs relate to what pressure

A

700-1100 RPM related to -50 to -80 mmHg

69
Q

Actions of the Real Lung

A

Gas exchange
Filtration
Immune Function
Biochemical function

70
Q

Actions of the Artificial Lung

A 
Gas exchange
Secondary actions (filtration; drug delivery)
71
Q

Diffusion proportion

A

Diffusion prop (PAS)/(Distance sq rt MW)

72
Q

Only True membrane

A

Silicone

73
Q

Surface Area of Natural vs Membrane

A 
Natural= 70 m^2
Membrane= 0.6-4 m^2
74
Q

Blood Path Width Natural vs Membrane

A

Natural 8 um

Membrane 200 um

75
Q

Blood path length Natural vs membrane

A

Natural 200 um

Membrane 250,000 um

76
Q

Membrane thickness Natural vs membrane

A

Natural 0.5 um

Membrane 150 um

77
Q

Maximum O2 Transfer Natural vs membrane

A

Natural 2,000 ml/min

Membrane 400-600 ml/min

78
Q

Oxygen gradient Natural vs membrane

A 
Natural 105 (alv) - 40 (ven) = 65
Membrane [160 to 760] - 40= [120 to 720]
79
Q

Carbon dioxide gradient natural vs membrane

A

Natural 40-45 = 5

Membrane 45 - 0 = 45

80
Q

CO2 during gas exchange

A

Chemical Reaction 0.4 seconds
Red Cell (including chemical reaction)
Plasma (lease amount of time)
Alveolar Wall

81
Q

O2 during gas exchange

A 
Alveolar Wall (most time) 0.25 seconds
Plasma (third most) 0.1 second
Red Cell (second most) 0.2 seconds
Chemical reaction (least)
82
Q

Who made the film oxygenator?

A

Gibbon

83
Q

Who made the rotating screen?

A

Dennis

84
Q

Who made the bubble oxygenator?

A

DeWall-Lillehei

85
Q

Who made the coil membrane?

A

Kolf

86
Q

How do you remove bubbles with a bubble oxygenator?

A

Separation

Absorption

87
Q

How do you defoam a bubble oxygenator?

A

Silicon Antifoam-A (96% liquid polymer dimethylpoysiloxane and 4% particulate silica)
Bubble mechanically restrained by mesh net
Area low blood flow velocity-allow bubble chance to rise to surface

88
Q

Pressure drops for bubble oxygenator & membrane oxygenator

A

30 mmHg bubble oxygenator

100 + mmHg membrane oxygenator

89
Q

Where is a bubble oxygenator placed?

A

Placed before the arterial pump head

90
Q

What materials does the defoaming/dububbling area have?

A

Steel wool
Polyurethane foam
Silicone Antifoam-A

91
Q

What does a heat exchanger do in a bubble oxygenator?

A

Transfer heat
Additional gas exchange
Additional air removal

92
Q

Basic components of a bubble oxygenator system

A 
Gas sparger
Mixing column (turbulence)
Defoaming/Debubbling area
Heat exchanger
Arterial reservoir
93
Q

Archimedes Principle

A

principle that states that a body immersed in a fluid is buoyed up by a force equal to the weight of the displaced fluid.

Buoyancy- used to eliminate air bubbles in the arterial reservoir

94
Q

Bubble Size and Surface Area

A

Small: Surface: Volume ratio is high
Large: Surface: Volume ratio is low

95
Q

What size bubbles has faster equilibration?

A

Small bubbles

96
Q

Bubble size and O2 exchange

A

Small: O2 exchange efficient
Larger: O2 exchange less efficient

97
Q

Bubble size and CO2 exchange

A

Small: Co2 exchange inefficient
Large: CO2 exchange efficient

98
Q

Bubble size and GME potential

A

GME potential is high with small bubbles and low with large bubbles

99
Q

What is FiO2 always set to?

A

100%

100
Q

What is the purpose of turbulence?

A

Increases efficiency of gas exchange

101
Q

Where does secondary gas exchange occur?

A

Heat exchanger/ defoamer

102
Q

LOW Gas:Blood Flow

A

Decrease O2 transfer
Decreased CO2 transfer
Arterial PO2 goes down
Arterial PCO2 goes up

103
Q

HIGH Gas: Blood Flow

A

Increased O2 transfer
increased co2 transfer
arterial PO2 goes up
arterial PCO2 goes down

104
Q

Bubble Oxygenator Disadvantages

A

Balance O2 and CO2 transfer difficult to achieve
GME
Defoaming/filter increase foreign surface exposure w.o significant contribution to gas exchange efficiency
Direct blood:gas interaction damaging to plasma proteins and blood components

105
Q

Membrane Types

A

Coil
Flat Plate
Capillary

106
Q

“True Membrane”

A

Complete barrier between the gas side and the blood side

Ex. Silicon

107
Q

Hollow Fiber Oxygenators

A 
Fibers:
200-250um in diameter
10-15 cm long
25-50 um thick
Blood flow Extra luminal/Intraluminal
108
Q

Extraluminal Blood Flow

A

Blood outside, gas inside

Greater surface area: less prime volume, decrease resistance to blood flow

109
Q

Intraluminal Blood Flow

A

Blood inside, gas outside

110
Q

Permeability Equation

A

Solubility x Rate of diffusion

111
Q

Membrane Performance

A 
Gas transfer characteristics of "membrane"
(gas exchange occurs at "pores")
Surface area
Fiber design- size & flow pattern
Gas flow: Blood flow ratio
(Influence co2 exchange only)
Gas blender (100% oxygen & room air)
FiO2:O2
112
Q

Hollow Fiber Oxygenator Durability

A

long term use leads to “wetting” of the membrane surface resulting in plasma leakage through the pores; deterioration of oxygenator performance

113
Q

Hollow Fiber Oxygenator Efficiency

A

Still 2-8 times less efficient as the natural lung

Primary limitation to gas exchange is gas diffusion in the blood phase

114
Q

Capillaries: Natural Lung

A

0.5 to 1.0 um length

3 to 7 um diameter

115
Q

Capillaries: Artificial Lung

A

10-15 cm in length

150-250 um diameter

116
Q

Flow Patterns: Natural Lung

A

Minimize shear forces

Maximize RBC contact with capillary (1:1)

117
Q

Flow Patterns: Artificial Lung

A

High shear forces

RBC contact with “capillaries” is low

118
Q

Contact Time: Natural Lung

A

Not a limitation in gas exchange even at extreme exercise

119
Q

Contact Time: Artificial Lung

A

Gas exchange efficiency decrease with higher blood flows

120
Q

Biocompatibility is associated with…

A 
Type and composition of surface
Shear Forces
Pressure drop across oxygenator
surface area-to-volume ratio
Duration of exposure
patient status...

CV Perfusion Tech I (5 decks)

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