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Methods of Anesthesia I > Cardiac Surgery Concepts > Flashcards

Cardiac Surgery Concepts Flashcards

1
Q

CABG

A

coronary artery bypass

procedure where normal blood flow is restored to an area of the heart that has an obstructed coronary artery

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2
Q

3 steps for CABG

A

1- blood vessels are harvested
2- grafts are sewn proximal and distal to blockage
3- blood flows through graft and bypasses the blockage

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3
Q

what are the 3 vessels that can be harvested for CABG?

A 
radial artery (not common)
saphenous vein
left internal mammary artery (LIMA)
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4
Q

where is proximal anastomosis

A

on the aorta

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5
Q

where is distal anastomosis

A

on the coronary artery distal to obstruction

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6
Q

In what case would you have 1 proximal anastomosis and 3 distal anastomosis’?

A

triple bypass using the LIMA

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7
Q

Which anastomosis’ usually get sewn on first?

A

the distals

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8
Q

What is the most commonly used graft?

A

left internal mammary artery LIMA

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9
Q

what is the LIMA usually anastomosed to?

A

LAD

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10
Q

Are arterial or venous grafts preferred for CABG?

A

arterial because they have to carry arterial blood

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11
Q

10 year rate of reocculsion for saphenous (%)

A

60% rate of reocculsion

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12
Q

10 year patency rate for LIMA (%)

A

90%

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13
Q

which is more patent the LIMA or radial artery?

A

LIMA

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14
Q

what is the most likely reason for the high patency of the LIMA?

A

it is a “live graft” meaning that the proximal origin is left intact

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15
Q

which is less invasive PCI or CABG?

A

PCI- percutaneous coronary intervention

balloon angioplasty or stenting (alternative to CABG)

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16
Q

better 5 year survival and patency? CABG or PCI?

A

CABG

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17
Q

lower risk of stroke at 5 years? CABG or PCI?

A

PCI

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18
Q

drug eluting stents

A

newer stents that slowly release a drug in order to slow the narrowing process

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19
Q

cardiopulmonary bypass machine

A

“heart lung machine”

functions as heart and lungs bc drains deox blood and oxygenates and removes CO2 then pumps back into body

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20
Q

purpose of CPB machine

A

some cardiac surgeries require the heart to stop or drain blood from heart
the CPB machine allows the pt to stay alive

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21
Q

does the heart have to be arrested for cardiac surgery?

A

it is not mandatory but it is common and sometimes the surgeon will do it anyway

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22
Q

does the heart have to be arrested when the patient goes on cardiopulmonary bypass?

A

no, it is possible for the heart to remain beating while on bypass

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23
Q

how is the heart arrested?

A

surgeons inject cardioplegia into heart

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24
Q

what is in cardioplegia?

A

potassium
other additives:
glucose, magnesium, calcium, bicarb, buffers, and free radical scavengers (mannitol)
it can be mixed and injected with blood

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25
Q

when do you need to drain the blood from the heart?

A

any surgery where you have to open up the heart

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26
Q

6 parts of the CPB machine circuit

A

1- deox blood is drawn from heart through venous cannula
2- venous blood is stored in venous reservoir
3- blood sent through oxygenator/heat exchanger and arterial filter
4/5- blood reinfused into the body via “main pump” that pumps blood into aorta through “arterial cannula”
6- aortic cross clamp is usually placed on ascending aorta

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27
Q

what are the places that the venous cannula is placed?

A

right atrium (most common)
SVC
IVC
femoral vein

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28
Q

what does the venous reservoir do?

A

stores a surplus of blood and helps remove any air that inadvertently entered the bypass circuit

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29
Q

what happens during step 3 of the CPB machine (4)

A

fat globules and air particles are filtered out
temp is controlled
blood oxygenated
CO2 removed

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30
Q

what are the two reasons that an aorta crossclamp is placed?

A

1-prevent blood from backing up into the heart

2- keep heart arrested by keeping cardioplegia solution in heart

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31
Q

what are the 8 bypass machine components?

A 
venous cannula(s)
venous reservoir
main pump
oxygenator
heat exchanger
arterial filter
arterial cannula
ultrafilter
cell salvage suction
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32
Q

when can you not use a venous cannula in the RA?

A

when you have right sided heart operation

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33
Q

what is the most common venous cannulas to use for open right sided heart surgeries?

A

SVC and IVC cannulas

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34
Q

what cannula can you place without having to open the chest?

A

femoral cannula (venous and arterial)

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35
Q

when is the femoral and arterial cannulation for CPB particularly useful?

A

when bypass must be initiated emergently

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36
Q

what are the two primary purposes of the venous reservoir?

A

1-remove air that enters the venous drainage line

2- stores a surplus of blood in the bypass circuit

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37
Q

does the traditional venous reservoir remove all air in the venous blood?

A

no

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38
Q

what does the reservoir act as a buffer for?

A

imbalances between venous return and arterial flow, when the heart and lungs are exsanguinated the reservoir may need to hold as much as 1-3 L

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39
Q

main pump

A

pumps blood to the body via arterial cannula and it has the option of pulsatile flow or non pulsatile flow

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40
Q

non pulsatile flow

A

more common since 2016

centrifuge pump

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41
Q

pulsatile flow

A 
new technique (less common since 2016)
roller or diagonal pumps
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42
Q

advantage of pulsatile flow

A

perfusion is better because it is more physiologic and stimulates the endothelium

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43
Q

disadvantage of pulsatile flow

A

achieving pulsatile flow from CPB machine is difficult

you could damage the blood elements

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44
Q

heat exchanger

A

cools and heats blood

allows perfusionist to control the temp of pt

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45
Q

what can form when blood is heated?

A

air bubbles bc gas solubility decreases as temp increases

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46
Q

what type of temp control is implemented during CPB

A

modest hypothermia ~34 degrees C for organ protection

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47
Q

advantages to modest hypothermia (2)

A

decreases oxygen requirements

decreases anesthetic requirements (hypothermia acts as anesthetic)

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48
Q

decreasing body temp by 1 degree decreases cerebral oxygen consumption by how much

A

5%

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49
Q

decreasing body temp by 10 degree decreases cerebral oxygen consumption by how much

A

50%

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50
Q

disadvantages of hypothermia (2)

A

more likely coagulopathy (more bleeding)

increased blood viscosity (decrease perfusion)

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51
Q

3 things oxygenator does

A

oxygenates blood
removes co2
site for volatile agent entry into bypass machine (perfusionist controls volatile agent)

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52
Q

2 types of oxygenators

A

bubble oxygenator

membrane oxygenator

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53
Q

bubble oxygenator

A

simple and low cost
more trauma to blood
RARELY USED

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54
Q

membrane oxygenator

A

increased complex and cost
less blood trauma
USED MORE COMMON

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55
Q

what is the main problem with oxygenator

A

damages blood
inflammatory respinse/organ dysfunction
decrease white blood cells and platelets and increased PAP

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56
Q

arterial filter

A

removes fat globules and air bubbles from circuit

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57
Q

what causes the spontaneous formation of microbubbles in the extracorpreal circuit?

A

excessive negative pressure in particular in the venous part of circuit

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58
Q

ultrafilter

A

hemoconcentrator that is sometimes added

removes excess water and electrolytes when low Hct

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59
Q

what are the two types of suction used during CPB?

A

standard suction

blood salvage suction

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60
Q

what are the three types of blood salvage suction

A

cardiotomy suction
cell saver suction
left ventricular vent

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61
Q

blood salvage suction definition

A

blood that will eventually return to pt, decreases chance of pt needing donor transfusion

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62
Q

cardiotomy suction

A

aspirated blood from chambers and surgical field
prevents distension and air embolism
returned to extracorporeal circuit via cardiotomy reservoir

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63
Q

where does the blood go after it is in the cardiotomy reservoir?

A

venous reservoir

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64
Q

Is cardiotomy used before or after the patient is heparinized?

A

after

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65
Q

can cardiotomy suction be used when the patient is off the bypass machine?

A

No

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66
Q

cardiotomy suction advantage

A

it is whole blood

includes: clotting factors, platelets and PRBC

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67
Q

cardiotomy suction disadvantage (2)

A

1- blood is damaged by the bypass machine

2-contributes to hemolysis and particulate emboli during CPB

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68
Q

what type of suction is associated with a more pronounced systemic inflammatory response?

A

cardiotomy

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69
Q

How does the cardiotomy suction cause hemolysis, GME, fat globule formation, activation of coagulation and fibrinolysis, cellular aggregation and platelet injury or loss?

A

amount of room air that is aspirated with blood causes turbulence and high sheer stress that causes damage

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70
Q

cell saver suction definition (2)

A

1- blood suctioned from field, washed and centrifuged

2- RBCs moved to infusion bag and transfused back into patient

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71
Q

what is the Hct of cell saver blood?

A

50-70%

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72
Q

cell saver advantages 2

A

1- particles (fat, air, tissue) are filtered out

2- blood is less damaged bc it does not go through bypass machine

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73
Q

cell saver disadvantages 2

A

1 it is not whole blood (mostly PRBC)

2 takes longer before it can be reinfused

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74
Q

can you use cardiotomy and cell saver?

A

yes this is a good option to use both, choose one depending on the type of fluid

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75
Q

left ventricle vent placement

A

inserted into the left ventricle through the pulmonary vein

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76
Q

what blood does the LV vent remove?

A

venous blood not picked up by venous reservoir (bronchial and thebesian veins)

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77
Q

purpose of LV vent

A

prevent left ventricular distension

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78
Q

what is the most likely time to get an air embolism with LV vent? prevention?

A

insertion or removal of the vent, or excessive suction

prevention by letting heart fill before insertion and flooding the field with fluid during removal

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79
Q

what does excessive suction lead to?

A

air introduction drawn from purse string sutures in left atrium or aorta

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80
Q

what is the most common way of arresting the heart?

A

antegrade cardioplegia (CP)

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81
Q

antegrade cardioplegia definition

A

arresting the heart by injecting cardioplegia into the coronary arteries through the coronary ostia (os)

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82
Q

coronary ostia (os)

A

the openings from the aorta to the coronary arteries

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83
Q

what is the most common way to do antegrade cardioplegia?

A

CP is injected into the aortic root via cardioplegia cannula
cross clamp is needed to keep CP from washing out into the body

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84
Q

what is the less common way to do antegrade CP?

A

direct cannulation of the coronary os and CP is injected through those

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85
Q

how do we perfuse the heart during CPB?

A

the CP line can also infuse blood into the coronary arteries so the heart is perfused

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86
Q

what are the the two reasons that you would need to perfuse the heart via the CP line?

A

ascending aortic clamp is placed

heart needs to be arrested

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87
Q

retrograde CP definition

A

CP being injected retrograde through the coronary sinus

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88
Q

what is the main risk with retrograde CP?

A

coronary sinus is more likely to rupture during CP injection because its a vein, surgeon will measure pressure during injection

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89
Q

steps to monitoring pressure with retrograde cardioplegia (3)

A

1- surgeon throws sterile non compliant tubing over drape (attached to CP line)
2- anesthetist hooks tubing to either CVP or PAP stopcock on triple transducer
3- during phase when heart is arrested the stopcock will be off to the pt and open to the retrograde line

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90
Q

Stopcock on transducer is turning to the side; what are you measuring?

A

CVP or PAP

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91
Q

stopcock on transducer is turned up; what are you measuring?

A

retrograde cardioplegia (if attached)

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92
Q

what are the two indications for retrograde CP?

A

1- helps arrest areas of heart distal to high grade obstruction
2- helps arrest heart when antegrade CP would wash out easily

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93
Q

what situations would antegrade CP wash out easily?

A

ascending aorta repair

open aortic valve repair

94
Q

where does the aortic cross clamp need to be placed in reference to the arterial cannula

A

proximal to the arterial cannula on the ascending aorta

95
Q

what would happen if you placed the aortic cross clamp while the heart was beating and full of blood?

A

heart attack or aortic rupture and death

96
Q

sequence for arresting the heart and going on bypass (3)

A

drain blood from heart via venous cannula
place aortic cross clamp
then arrest heart with CP solution

97
Q

When can you place an aortic cross clamp on a beating heart?

A

when the heart has been drained of blood

this will happen when going on and coming off pump

98
Q

what two ways can the heart be arrested without using an aortic cross clamp?

A

retrograde CP

directly cannulating the coronary os for CP

99
Q

advantages of aortic cross clamp 3

A

1 easier to arrest heart
2 prevents air from entering circulation
3 prevents reinfused blood from backing up into heart

100
Q

disadvantage to aortic cross clamp 2

A

1physiologic perfusion to the heart is not possible
is perfused through CP cannula
2 increases risk of stroke from possible dislodging of emboli

101
Q

partial aortic cross clamp

A

used when graft is sewn in and hole must be made

also associated with emboli and stroke

102
Q

when are the two times that CPB is necessary

A

heart needs to be empty

heart is going to be arrested

103
Q

what are the two advantages to bypass

A

easier for surgeon

more hemodynamic stability

104
Q

what are the 7 disadvantages of CPB

A 
1-priming fluid causes hemodilution (Hct decrease)
2- aortic clamp usually placed
3- difficulty coming off pump
4- pulm complications more likely
5- perfusion less effective
6- pt blood is damaged
7- large volume shifts may occur`
105
Q

how much fluid is the bypass machine primed with?

A

2,000mL

106
Q

what % of the pts circulating blood volume is the hemofilutional bolus equal to

A

30-50%

107
Q

what are the contents of the priming fluid

A 
heparin
bicarb
mannitol
colloid
possible steroids or antifibrinolytics
108
Q

when would the machine be primed with blood?

A

pediatrics, to prevent over dilution of blood

109
Q

what are the two pulmonary complications that could be seen with bypass

A

pulmonary edema more likely from activation of complement

reduces the effectiveness of natural surfactant

110
Q

what are the two organs that have decreased perfusion on bypass and why does it matter

A

renal, hepatic

drugs arent cleared well

111
Q

3 causes of blood damage on bypass

A

hemolysis
platelet conc is reduced and clotting factor function decrease
intense inflammatory response

112
Q

what can the intense inflammatory response cause?

A

disturbances in vascular tone, permeability, fluid shifts and organ dysfunction
heart function compromised when coming off pump

113
Q

what can a large volume shift cause?

A

transient cerebral edema

114
Q

what is the part of the machine that determines whether it is an open or closed bypass system

A

the type of venous reservoir

115
Q

is an open or closed bypass system more common?

A

open bypass system

116
Q

open bypass system definition

A

venous drainage flows by gravity into venous reservoir thats open to atmosphere
air naturally vented but in direct contact with air (bad)
hardshell reservoir

117
Q

closed bypass system definition

A

venous reservoir removed from system or is closed to atmosphere
collapsible bag

118
Q

benefits to using the open bypass system

A

automatically eliminates air (less risk of air embolism)
volume delineation is clear
actively purging air from closed system is distracting

119
Q

advantages of closed bypass system 3

A

limited contact with air (limits injurt to elements of blood)
decreased inflammatory response and fewer hematological disruptions
some have smaller priming volumes

120
Q

disadvantages of closed bypass 3

A 
less precise visual monitoring of venous return
air is not automatically purged (requires additional systems)
less filters (more microemboli exiting)
121
Q

what parts does a mini CPB circuit have

A

pump
oxygenator
reduced tubing length (reduction of priming volume)
arterial filter (usually)

122
Q

what parts does a mini CPB circuit NOT have

A

venous reservoir
cardiotomy suction
heat exchanger

123
Q

what is the priming volume reduced to in a mini cardiopulmonary bypass circuit?

A

600mL

124
Q

Is the mini CPB circuit open or closed?

A

closed (limits air contact)

125
Q

advantages of mini CPB circuit 4

A

advantages of closed system
improves myocardial protection (less problems restoring SR and less afib)
associated with less blood transfusion
associated with earlier recovery times and reduced ICU and hosp time

126
Q

why is mini CPB circuit associated with less blood transfusion

A

lower priming volume

less hemodilution

127
Q

disadvantages of mini cardiopulmonary bypass

A

demanding for perfusionist (must pay more attention to air handling)
some studies say it isnt beneficial

128
Q

off pump heart surgery

A

suction clamps applied
good bc no negative effects from bypass machine
bad bc clamps may cause significant hypotension and/or arrhythmias

129
Q

partial CPB

A

only drains part of venous blood and goes through the bypass machine and some blood goes through the pulmonary circulation

130
Q

if a surgeon attempts an off pump and the pt cant tolerate it what are the two options?

A

full bypass: heart arrested and heart perfusion non physiologic
partial bypass: heart beating and heart perfusion physiologic

131
Q

3 implications of partial CPB

A

heart must stay beating
pt needs to be oxygenated/ventilated/ volatile agent delivered
aortic clamp doesnt need to be placed

132
Q

left heart partial bypass 6

A

1-blood travels through right heart and pulm
2-some blood removed from left atrium and travels through machine and perfuses lower extremities
3-some blood stays in left atrium and goes out the aorta to perfuse the head
4- only left heart bypassed
5- blood already oxygenated
6- heart must stay beating and lungs must be ventilated

133
Q

left heart bypass circuit parts

A

tubing

centrifugal pump

134
Q

indication of left heart partial bypass

A

open descending thoracic aortic aneurysm repair

135
Q

what perfuses the head during partial left heart bypass

A

the heart

136
Q

what perfuses the lower body during partial left heart bypass

A

arterial cannula

137
Q

left/right heart bypass advantages 5

A

1 heart stays beating (physiological perfusion remains)
2 lower circuit prime volume
3 lower chance of postop renal failure
4 blood pressure is controlled by perfusionist
5 no air blood contact

138
Q

what does lower circuit prime volume lead to? 3

A

less hemodilution
less blood damage
less heparinization needed

139
Q

what is the target ACT?

A

150-200 seconds

140
Q

what are the % chance of renal failure for left heart bypass, simple cross clamp, and CPB?

A

left- 4%
simple- 9%
CPB- 11%

141
Q

left/right heart bypass disadvantages

A

no blood or fluid can be added to the bypass system (without reservoir)
pt cant be warmed or cooled by machine
air embolization may be more likely

142
Q

right heart bypass 4

A

1- venous cannula in SVC and IVC remove blood and sent to machine
2- reinfused blood though arterial cannula in pulm artery, cross clamp on pulm artery
3- blood goes to lungs thus we need to ventilate and oxygenate
4- heart stays beating and lungs are ventilated

143
Q

why is there a lower stroke risk with right heart bypass

A

no aortic cross clamp is needed

144
Q

3 indications for right heart partial bypass

A

tricuspid valve repair
pulmonic valve repair
right ventricle assist device (RVAD) placement

145
Q

when on right heart partial bypass the surgeon can complete surgery without: (3)

A

arresting heart
clamping aorta
using oxygenator

146
Q

where do they place the cross clamps for ascending or aortic arch aneurysms?

A

proximal and distal to aneurysm

147
Q

what are the options to protect the brain when total body perfusion isnt feasible with arterial cannula due to clamp location (3)
can you use these together?

A

deep hypothermic circulatory arrest (DHCA)
retrograde cerebral perfusion
antegrade cerebral perfusion
** yes you can use more than one of these techniques

148
Q

deep hypothermic circulatory arrest

A

perfusionist makes pt so cold that oxygen demands are so low they can survive a short amount of time without perfusion

149
Q

indications for DHCA

A

ascending aorta repair
aortic arch repair
descending aorta repair
clipping certain complex brain aneurysms

150
Q

how does the circ arrest process work?

A

1- pt put on bypass
2- heat exchanger decreases temp
3- heart is arrested and circulation is slowed to near stand still
4- decrease in oxygen consumption allows for the pt to have minimal blood flow

151
Q

during circ arrest where is the arterial cannula placed?

A

femoral artery or axillary artery

152
Q

what is the target temp before starting circ arrest?

A

15 to 17 degrees C

longer the operation they may need to be colder

153
Q

what monitors are used to monitor the depth of hypothermia and ensure electrial silence during DHCA

A

BIS and EEG

154
Q

when is the EEG usually isoelectric?

A

between 15-20 degrees C

155
Q

how much longer is the patient cooled after they are isoelectric?

A

10 minutes to ensure homogenous cooling of brain

156
Q

how long is circ arrest safe? chart

A

temp – mins
20- 30-40
16- 45-60

157
Q

circ arrest should not be performed for longer than?

A

60 min

158
Q

time limit for most have no neurologic complications

A

<30 min

159
Q

time limit for increased incidence of brain injury

A

> 40 min

160
Q

time limit for most suffer from irreversible brain damage

A

> 60min

161
Q

who can tolerate longer periods of circ arrest?

A

neonates and children

162
Q

complications of DHCA 3

A

complications of hypothermia
neurologic complications
potential neurologic complications from cooling or rewarming pt too rapidly

163
Q

what can rapid cooling cause

A

<20 min to deep hypothermia

lower neurodevelopmental outcome scores

164
Q

what can rapid rewarming cause 4

A

organ damge
deleterious to neurologic outcome
promotes gas bubble formation (solubility decrease and temp increase)
cerebral desaturation and uneven warming

165
Q

what is the rewarming rate not to exceed?

A

1C core temp per 3 min of bypass time

166
Q

when should rewarming stop?

A

nasopharyngeal temp reaches 35C

167
Q

DHCA anesthetic management 2

A

1- must use nasal temp probe (reflection of brain temp)
2- additional brain protection
- periop steroids
-hyperoxygenation before
- 20 min of cooling for adequate cerebral protection
- pack head in ice
-intermittent cerebral perfusion in 15-20 min periods

168
Q

what are the two temp probes to have for circ arrest?

A

nasal (brain)

bladder (core)

169
Q

retrograde cerebral perfusion during circ arrest

A

extra perfusion line, perfuses head through SVC

170
Q

normothermic antegrade cerebral perfusion

A

extra perfusion line is placed in right axillary artery to perfuse head
USED WITHOUT CIRC ARREST

171
Q

antegrade cerebral perfusion

A

used with normothermia or circ arrest

disadvantage: may increase incidence of stroke

172
Q

cerebral oximetry

A

near infrared spectroscopy (NIRS) measure oxygen saturation in cerebral vessels (rSO2)

173
Q

what is the normal rSO2?

A

60-80%

174
Q

why is rSO2 lower than normal SO2?

A

cerebral vascular bed is 75% venous and 25% arterial

175
Q

what is cerebral oximetry an indicatory of?

A

cerebral perfusion

176
Q

if there is a low rSO2 value and cerebral perfusion has decreased what should you do?

A

increase blood flow and oxygenation to the head

177
Q

what are two applications for cerebral oximetry

A 
heart surgery (alerts the moment perfusion is disrupted to better intervene the issue)
sitting/beach chair surgery (easier to know if you are perfusing the brain rather than using the BP)
178
Q

when should the anesthetist intervene?

A

rSO2 < 50%
>20% drop from baseline rSO2
difference >30% from the left and right hemispheres

179
Q

what are the rSO2 values that correspond to poor neurologic outcomes

A

<45% absolute

>25% declines

180
Q

4 factors that decrease rSO2 values

A

decrease in cerebral blood flow (hypotension/low CO, hyperventilation)
hypoxemia
anemia
mechanical disturbances

181
Q

ways to increase cerebral SpO2 (6)

A 
1- increase cerebral perfusion pressure (MAP-ICP)
2- increase cerebral blood flow
3- increase FiO2
4- increase cardiac output
5- increase hematocrit
6- decrease cerebral metabolism
182
Q

ways to increase the cerebral perfusion pressure

A 
increase MAP (if hypotensive)
potentially decrease intracranial pressure ICP
183
Q

how do you decrease intracranial pressure ICP?

A

mannitol- decreases CSF production, shrinks brain cell volume
place lumbar drain

184
Q

how do you increase cerebral blood flow

A

increase PaCO2

nitroglycerin?

185
Q

PT

A

prothrombin time
examines extrinsic pathway of coagulation cascade
12-15sec

186
Q

PTT

A

partial thromboplastin time
examines intrinsic pathway of cascade
25-40 sec

187
Q

INR

A

international normalized ratio
standardized PT result
0.9-1.1

188
Q

standard unfractioned heparin

A

binds and enhances activity of antithrombin III 1000 fold

effects intrinsic pathway

189
Q

what can heparin be reversed by

A

protamine

190
Q

lovenox (enoxaparin)

A 
LMWH
dosed subcutaneously
longer lasting 12-24 hr
doesnt prolong PTT as much
not reversed reliably with protamine
191
Q

what is the half life of standard heparin?

A

1 hr when dosed intravenously

192
Q

what is a good test for lovenox

A

anti- Xa assay

193
Q

coumadin

A

warfarin
by mouth vitamin K antagonist
effects extrinisic pathway
effects PT and INR more

194
Q

what can warfarin be reversed with?

A

FFP

vitamin K

195
Q

plavix

A

clopidogrel
by mouth antiplatelet
not reliably reversed (usually with platelets)
half life 5-7 days

196
Q

dual antiplatelet therapy

A

aspirin and plavix

indicated for recent coronary balloon angioplasty or stent

197
Q

pt that is on dual antiplatelet therapy should wait how long for elective surgery if balloon angioplasty?

A

at least 14 days

198
Q

pt that is on dual antiplatelet therapy should wait how long for elective surgery if metal stent placed

A

at least 6 weeks

199
Q

pt that is on dual antiplatelet therapy should wait how long for elective surgery if drug eluting stent placed

A

at least a year

200
Q

what if the pt is on dual antiplatelet therapy and has to have emergency surgery?

A

aspirin usually continued and surgeon/cardio make plan for pt needs

201
Q

xarelto (rivaroxiban)

A

by mouth direct Xa inhibitor

reversed with prothrombibn complex concentrates (PCC)

202
Q

when should xarelto be discontinued before surgery?

A

at least 24 hours before

203
Q

eliquis (apixaban)

A

direct factor Xa inhibitor

reversed with PCC

204
Q

when should eliquis be discontinued before elective surgery?

A

at least 48 hours before

205
Q

heparin dose for standard CPB

A

300-400 units/kg dosed before aortic cannulation

206
Q

ACT

A

activated clotting time; blood test used to measure coagulation during cardiac surgery when heparin is given

207
Q

normal ACT

A

100-150 sec

208
Q

goal ACT prior to going on pump

A

> 450 sec

209
Q

heparin induced thrombocytopenia (HIT)

A

patients immune system has antibodies against heparin which:
thrombocytopenia (lack of platelets)
thrombosis (clotting)
usually occurs with standard heparin

210
Q

what is used for anticoagulation in patients that have HIT?

A

direct thrombin inhibitors (argatroban)

more difficult to control post op bleeding

211
Q

antithrombin III deficiency

A

low levels of ATIII and show resistance to heparin

can be acquired as a result of recent heparin administration

212
Q

anesthetic management of ATIII deficiency

A 
replaced AT III (concentrates available)
administer FFP (if concentrates are not available)
213
Q

protamine

A

salmon sperm
reverses heparin
brings ACT back to normal

214
Q

when is protamine given during cardiac surgery?

A

when the pt is taken off bypass

215
Q

dose of protamine

A

1mg per 100 units heparin

216
Q

how is heparin given?

A

peripherally and slowly over 10 min

217
Q

protamine mechanism of action

A

binds heparin and it is no longer bound to ATIII

218
Q

what does protamine do when given without prior administration of heparin?

A

it is an anticoagulant

219
Q

what could excess protamine cause?

A

increase bleeding especially in thrombocytopenia or low VIII

220
Q

2 adverse effects of protamine

A

(with rapid/central admin)
hypotension
anaphylactoid reaction

221
Q

when is a anaphylactoid reaction to protamine more likely?

A

prior exposure to protamine
allergic to fish
male pts with vasectomy
diabetics exposed through insulin

222
Q

why does a male with vasectomy have reaction to protamine?

A

because they can develop antibodies to sperm

223
Q

what reverses the effects of warfarin?

A

FFP and vitamin K
FFP and PCC work quickest but they dont reverse they just replace the clotting factors
vitamin K will help the patient make their own clotting factors

224
Q

Prothrombin Complex Concentrates (PCC)

A

contains vitamin K dependent clotting factors

reverse the effects of coumadin, xarelto, eliquis

225
Q

What can PCC replace in massive transfusion protocol?

A

FFP

226
Q

how much higher of a concentration are the clotting factors in PCC compared to FFP

A

25 fold higher

227
Q

1 vial of PCC= _?__ units FFP?

A

2

228
Q

advantages of PCC

A

twice as fast as FFP
single dose every 24 hours (less volume required)
half the adverse effects of FFP
faster prep time (no thawing)

229
Q

disadvantages of PCC

A

20x more expensive
shorter acting than FFP
(should be administered with vitamin K)

230
Q

FFP vs PCC???

A

jury still out
some studies say half blood products used for PCC
some studies say higher mortality rate at 45 days for PCC

Methods of Anesthesia I (10 decks)

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