Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Methods of Anesthesia > Cardiac Surgery Concepts > Flashcards

Cardiac Surgery Concepts Flashcards

1
Q

Procedure that restores normal blood flow to an area of the heart by creating new routes around obstructive coronary arteries

A

Coronary Artery Bypass Graft (CABG)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Explain the steps of a CABG

A
  1. Blood vessel(s) from the body are removed (harvested)
  2. Harvested vessels (grafts) are sewn proximal and distal to an atherosclerotic coronary artery
  3. Blood now flows through the harvested vessel and “bypasses” the blocked coronary artery
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What blood vessels can be harvested for a CABG?

A
  1. Saphenous vein
  2. Left internal mammary artery (LIMA)
  3. Radial artery
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where is the proximal anastomosis in a CABG?

A

On the aorta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where is the distal anastomosis in a CABG?

A

On the coronary artery, distal to the obstruction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What anastomosis does the surgery typically sew on first?

A

Distal (coronary artery)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

The LIMA only requires a (proximal/distal) anastomosis?

A

Distal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Most commonly used graft for CABG

A

Left Internal Mammary Artery (LIMA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where is LIMA usually anastomosed?

A

With the LAD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why are arterial grafts preferred over venous grafts for CABG?

A

Coronary arterial pressure will damage the saphenous endothelium more quickly, leading to a reocclusion rate at 10 years for venous grafts of ~60%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Types of Percutaneous Coronary Intervention (PCI)

A

Balloon angioplasty and cardiac stenting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Alternative to CABG, less invasive, used for less severe cases of CAD

A

Cardiac stenting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Tends to show better 5 year survival and patency rates, but carries a higher risk of stroke at 5 years

A

CABG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Summary of cardiopulmonary bypass (CPB) machine

A

-Functions as both heart and lung by draining deoxygenated blood from the body, oxygenating it and removing CO2, then pumps oxygenated blood back into the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Purpose of the cardiopulmonary bypass machine (reasons to use it)

A

-When the heart needs to be stopped or empty

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why would you want to drain blood from the heart?

A

If you need to open it to expose a valve for open valve repair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

True/false: the heart has to be arrested for heart surgery

A

False. It is not mandatory in all situations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why would a surgeon stop the heart for surgery if it is not necessary?

A

It is easier to operate on a non-moving target

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

When is the heart commonly arrested?

A

When a patient goes on CPB, although it is not required

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Solution used to arrest the heart

A

Cardioplegia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Components of cardioplegia

A

Potassium rich solution with glucose, magnesium, calcium, bicarb, buffers and free radical scavengers (Mannitol)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Can cardioplegia be injected with blood?

A

Yes, cardioplegia can be mixed and injected with blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Most common way of arresting the heart

A

Antegrade cardioplegia via the aortic root

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is antegrade cardioplegia?

A
  • Injecting cardioplegia (CP) into the coronary arteries through the coronary os
  • Can be into the aortic root through a cardioplegia cannula or direct cannulation of the coronary os
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How is CP injected into the aortic root?

A
  • A cross clamp is placed on the ascending aorta to keep the CP from washing out into the body
  • Injected through a cardioplegia cannula
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How can the heart get sufficient oxygen in cases where 1. an ascending aortic cross clamp is placed or 2. the heart needs to be arrested

A

Cardioplegia lines bc they can also infuse blood into the coronary arteries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Where is retrograde CP injected?

A

Coronary sinus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How do you prevent coronary sinus damage with retrograde CP?

A

Measure the pressure within the coronary sinus as CP is injected so it does not rupture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

When is retrograde CP used?

A

For aortic valve replacement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

How is pressure monitored with retrograde cardioplegia?

A
  1. The surgeon throws sterile, non-compliant tubing over the drape
  2. Anesthetist hooks tubing to either CVP or PAP stopcock on triple transducer
  3. When the heart is arrested, stopcock is turned off to the patient and open to the retrograde line
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Why can’t you hook up retrograde cardioplegia monitoring to the A-line transducer?

A

You need to measure the A-line during bypass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

True/false: You can measure CVP/PAP while monitoring retrograde cardioplegia

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What stopcock position can measure CVP/PAP?

A

To the side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What stopcock position can measure retrograde cardioplegia pressure?

A

Up (toward the patient)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Indications for retrograde CP

A
  1. Arrests areas of the heart distal to high grade obstructions
  2. Where antegrade CP would easily wash out (ascending aorta repair, open aortic valve repair)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Describe the CPB machine circuit

A
  1. De-oxygenated blood is drawn away from the heart through a venous cannula
  2. Venous blood is stored in a venous reservoir
  3. The venous blood is sent through an oxygenator, heat exchanger and arterial filter
    4/5. Oxygenated blood is reinfused into the body via a “main pump” that pumps the blood into the aorta through an arterial cannula
  4. An aortic cross clamp is usually placed on the ascending aorta
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Where is the venous cannula is usually placed?

A

In the R atrium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Where can the venous cannula be placed?

A

R atrium
SVC/IVC
Femoral vein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What does the venous reservoir do?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What is the purpose of the aortic cross clamp?

A
  1. Prevent blood from the arterial cannula from backing up into the heart
  2. Allow the heart to stay arrested by keeping the injected cardioplegia in the heart
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What are the components of the bypass machine? (9)

A
  1. Venous cannula(s)
  2. Venous reservoir
  3. Main pump
  4. Oxygenator
  5. Heat exchanger
  6. Arterial filter
  7. Arterial cannula
  8. Ultrafilter
  9. Cell salvage suction (cardiotomy suction, cell saver suction and left ventricular vent)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

When can you NOT use a venous cannula in the R atrium?

A

During R sided heart operations bc it wouldn’t prevent blood from gushing out of the surgical site or keep air from being sucked in

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Where would a venous cannula be placed in the traditional open R sided heart operation?

A

In the superior and inferior vena cavas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

How do you place a venous cannula without opening the chest?

A

Through the femoral vein, threaded up into the R atrium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

How can an arterial cannula be placed without opening the chest?

A

Through the femoral artery, threaded up in the aorta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

When is femoral arterial and venous cannulation particularly useful?

A

When CPB must be initiated emergently

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

2 primary purposes of the venous reservoir in CPB

A
  1. The venous cannula can remove any air that inadvertently enters the venous drainage line
  2. The venous reservoir also stores a surplus of blood in the bypass circuit
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Main pump options

A
  1. Non-pulsatile (more common, uses centrifugal pump)

2. Pulsatile (newer, “roller” or “diagonal” pump

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Purpose of the main pump in CPB

A

Pumps blood to the body via the arterial cannula via pulsatile or non-pulsatile flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Advantages of pulsatile flow

A

Perfusion is better because it is more physiologic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Disadvantages of pulsatile flow

A
  1. Difficult for perfusionist

2. More damage to blood elements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Purpose of the heat exchanger in CPB

A

Cools and heats blood to control temperature of the pt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Modest hypthermia temperature

A

34 C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Purpose of modest hypothermia

A

34 C implemented while the pt is on CPB for organ protection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Advantages of modest hypothermia

A
  1. Decreases O2 requirements

2. Decreases anesthetic requirements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

A decrease in body temperature 1C decreases cerebral O2 consumption by ___%

A

5%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

A decrease in body temperature 10C decreases cerebral O2 consumption by ___%

A

50%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

Disadvantages of hypothermia

A
  1. Increases the chances of coagulopathy (increases bleeding risk)
  2. Increases blood viscocity, which can decrease perfusion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

Role of the oxygenator in CPB

A
  1. Oxygenates the blood
  2. Removes CO2
  3. Site of volatile agent entry into the bypass machine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

2 types of oxygenators in CPB

A
  1. Bubble oxygenator

2. Membrane oxygenator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

Advantages and disadvantages of bubble oxygenators in CPB

A
  1. Simple and lower cost
  2. More trauma to the blood
  3. Rarely used
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

Advantages and disadvantages of membrane oxygenators in CPB

A
  1. Less blood trauma
  2. Increased complexity and cost
  3. Standard oxygenator used today
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

Biggest problem with the oxygenator

A

Damages the blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

Role of the arterial filter in CPB

A

Removes fat globules and air bubbles from the bypass circuit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

Role of the ultrafilter in CPB

A

Sometimes added to the circuit to remove excess water and electrolytes from the circulating volume, concentrating the blood in a pt with undesirably low hematocrit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

Why would you want to use an ultrafilter in CPB?

A

To concentrate blood in a pt with an undesirably low hematocrit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

Types of suction used in CPB

A
  1. Standard (regular OR suction)

2. Blood salvage suction (cardiotomy suction, cell saver suction, left ventricular vent)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

Suctioned blood that will eventually be returned to the patient in CPB

A

Blood salvage suction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

Advantage of blood salvage suction in CPB

A

Decreases the chances of the pt needing a donor transfusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

In CPB, takes blood from the field and returns it to a “cardiotomy reservoir” before ultimately ending up in the venous reservoir

A

Cardiotomy suction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

When is cardiotomy suction used in CPB

A

After the pt is heparinized while the pt is on the bypass machine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

Advantage of cardiotomy suction

A
  1. It is whole blood, so it includes clotting factors, platelets and PRBCs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

Disadvantages of cardiotomy suction

A
  1. Blood going through is damaged by the bypass machine, therefore is associated with a more pronounced systemic inflammatory response and coagulopathy
  2. Significant contributor to the hemolysis and particulate emboli that occurs during CPB
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

In CPB, suctioned blood from the field is washed and centrifuged, which separates RBCs from the plasma, platelets and particulate matter. RBCs are moved to an infusion bag and transfused back to the patient

A

Cell saver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

Hematocrit of cell saver blood

A

50-70%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

Advantages of cell saver

A
  1. Particles such as fat, air and tissue are filtered out of the blood
  2. Blood is less damaged when it gets returned to the patient
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

Disadvantages of cell saver

A
  1. It is NOT whole blood

2. Takes longer before it can be reinfused into the patient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

Removes all venous blood that was not picked up by the venous reservoir (blood from bronchial and Thebesian veins)

A

Left ventricular vent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

Where is the left ventricular vent inserted?

A

Into the left ventricle through the pulmonary vein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

Risk of using left ventricular vent

A

Air embolism

81
Q

Aortic cross clamp location

A

Proximal to the arterial cannula on the ascending aorta

82
Q

Why does the aortic cross clamp need to be placed proximal to the arterial cannula?

A

So perfusion to the head and rest of the body is possible

83
Q

What would happen if you placed the aortic clamp prior to bypass on a beating heart full of blood?

A

The patient would die right away from either a massive heart attack or a ruptured aorta

84
Q

What is the sequence for arresting the heart and going on bypass?

A
  1. Drain the blood from the heart via the venous cannula
  2. Place the aortic cross clamp (while the heart is still beating)
  3. Arrest the heart by injecting cardioplegia
85
Q

When is it okay to clamp the aorta while the heart is beating?

A

If the heart is drained of blood on bypass

86
Q

When can the heart be arrested without a clamp?

A

If the surgeon uses retrograde cardioplegia OR directly cannulates the coronary arteries for cardioplegia

87
Q

Advantages of the aortic cross clamp

A
  1. Easier to arrest the heart (keeps CP in)
  2. Prevents air inside the heart from entering circulation
  3. Prevents re-infused blood (from arterial cannula) from backing up into the heart
88
Q

Disadvantages of aortic cross clamp

A
  1. Physiologic perfusion to the heart is not possible

2. Increases risk of stroke from a possible dislodging emboli

89
Q

Purpose of partial aortic cross clamp

A

Allows a hole to be made in the aorta for a graft to be sewn without blood shooting out everywhere

90
Q

Disadvantage of partial aortic cross clamp

A

Associated with emboli and stroke

91
Q

When is cardiopulmonary bypass necessary?

A

When the heart needs to be emptied of blood or the heart is going to be arrested

92
Q

Advantages of bypass

A
  1. The surgery is “easier” for the surgeon

2. There is more hemodynamic stability

93
Q

Disadvantages of CPB

A
  1. Priming fluid causes hemodilution (Hct decreases)
  2. An aortic cross clamp is usually placed, which can lead to emboli
  3. May be difficult coming off the pump (re-establish an effective heart beat and contractility)
  4. Pulmonary complications are more likely
  5. Tissue perfusion is less effective
  6. The patient’s blood gets damaged by the bypass machine
  7. Large volume shifts can occur
94
Q

How much fluid is used to prime the bypass machine

A

2000 ml

95
Q

Potential contents of priming fluid

A

Heparin, bicarb, mannitol, colloid and possibly steroids or antifibrinolytic agents

96
Q

Why might bypass machines need to be primed with some blood in pediatrics?

A

Peds blood volume is small and priming with some blood can prevent over-dilution

97
Q

What is an open bypass sytem?

A
  • more common
  • venous drainage freely flows by gravity into a venous reservoir that is open to the atmosphere
  • Any air is naturally vented (good), but blood is in direct contact with air (bad)
98
Q

What is a closed bypass system?

A

Either the venous reservoir has been removed from the system or it is in the system but closed to the atmosphere

99
Q

Is the collapsible bag configuration considered open or closed bypass, and why?

A

Closed because the blood in the bag is not exposed to room air

100
Q

Is the hardshell reservoir considered open or closed bypass, and why?

A

Open because the blood in the reservoir is exposed to surrounding air

101
Q

What is the primary perfusion system to CPB?

A

Open

102
Q

What is the priming volume for the mini cardiopulmonary bypass?

A

600 ml

103
Q

Is mini CPB open or closed?

A

Closed

104
Q

Components of the mini CPB

A
  1. Pump
  2. Oxygenator
  3. Reduced tubing length
  4. Arterial filter (usually)
105
Q

What components are missing in the mini CPB?

A
  1. Venous reservoir
  2. Cardiotomy suction
  3. Heat exchanger
106
Q

Advantages of mini CPB

A
  1. All advantages of a closed bypass system
  2. May improve myocardial protection
  3. Associated with less blood transfusion
  4. Associated with earlier recovery times and reduced ICU/total hospitalization time
107
Q

Disadvantages of mini CPB

A
  1. Demanding for the perfusionist

2. May not be beneficial (minimal effect on inflammation and coagulation)

108
Q

How do you limit the motion of the heart while it is beating and being operated on? (off pump surgery)

A

Suction clamps are applied

109
Q

Downside to off pump heart surgery

A

Suction clamps can cause significant hypotension and/or arrhythmias

110
Q

Draining part of the venous blood from the patient’s body while the rest of the blood stays in the heart and travels to the body

A

Partial cardiopulmonary bypass

111
Q

How does partial CPB work?

A

Some blood is removed from the R atrium through the venous cannula. The blood goes through the bypass machine and perfuses the body through the arterial cannula
Some blood stays in the heart and goes to the lungs before being pumped into the L ventricle and out the aorta

112
Q

Why would a patient be put on partial bypass?

A

If the patient cannot tolerate the procedure off pump

113
Q

What are 2 options if a surgeon cannot do a procedure off pump because the patient cannot tolerate it?

A
  1. Place pt on full bypass (non-physiologic perfusion)

2. Place pt on partial bypass (physiologic perfusion)

114
Q

True/false: Partial flow through the arterial cannula in partial CPB is enough to prevent hypotension

A

True

115
Q

Implications of partial CPB

A
  1. Heart must stay beating
  2. Blood that stays in the heart needs to pick up volatile agent and be oxygenated/ventilated
  3. No need for an ascending aortic clamp
116
Q

How does the L heart partial bypass work?

A
  1. Blood travels through the R heart and lungs as normal
  2. Some blood is removed from the L atrium through a “venous” cannula, travels to bypass and perfuses lower extremities through the arterial cannula
  3. Some blood stays in L atrium and goes out the aorta to perfuse the head
117
Q

Implications of L heart partial bypass

A
  1. Only the L heart is bypassed
  2. All blood flowing to bypass is oxygenated
  3. Heart must stay beating and lungs must stay ventilated
118
Q

What is not needed in the bypass machine on L heart partial bypass?

A

Oxygenator, reservoir or heat exchanger

119
Q

Indication for L heart partial bypass

A

Open descending thoracic aortic aneurysm repair

120
Q

Advantages of L heart bypass

A
  1. Heart stays beating and does not need to be restarted (physiologic perfusion)
  2. Lower circuit prime volume leads to:
    - Less hemodilution
    - Less blood damaged
    - Less heparinization needed (target ACT 150-200s)
  3. Lower chances of postop renal failure
  4. Blood pressure can be controlled by perfusionist
  5. No direct blood-air contact in the circuit
121
Q

Disadvantages of L heart bypass

A
  1. No blood or fluid can be added to the bypass system (no reservoir)
  2. The pt cannot be actively warmed or cooled
  3. Systemic air embolization is more likely without the reservoir
122
Q

How does R heart bypass work?

A
  • Venous cannulas from SVC and IVC remove deoxygenated blood from the R side of the heart and send it to bypass
  • Blood is reinfused into the pulmonary artery through an arterial cannula, which is distal to a cross clamp on the pulmonary artery
  • Blood from the machine goes to the lungs
  • The heart stays beating and the lungs are ventilated
123
Q

Why is it okay for the heart to pump against the clamp in R heart bypass?

A

The heart is empty

124
Q

Indications for R heart bypass

A
  1. Tricuspid valve repair
  2. Pulmonic valve repair
  3. R ventricular assist device
125
Q

Advantages to the R heart bypass

A
  1. Does not stop the heart
  2. Does not need to clamp the aorta
  3. Does not need the oxygenator
126
Q

Disadvantages of the R heart bypass

A

Same as the L heart bypass

127
Q

How do you repair aortic aneurysms without clamping?

A
  1. Add another perfusion cannula (retrograde cerebral perfusion or antegrade cerebral perfusion)
  2. Make the patient so cold that their metabolic requirements would be low enough to survive a short period of time with no perfusion (DHCA-deep hypothermic circulatory arrest)
128
Q

What is DHCA?

A

Deep hypothermic circulatory arrest; the perfusionist puts the patient on bypass, makes the patient profoundly hypothermic and then turns the bypass off

129
Q

Indications for DHCA

A
  1. Ascending aorta repair
  2. Aortic arch repair
  3. Descending aorta repair
  4. Clipping of certain complex brain aneurysms
130
Q

How does DHCA work (detailed)

A
  1. Patient is on CPB, heat exchanger decreases patient’s temperature
  2. The heart is arrested, circulation through bypass is slowed to a near standstill
  3. The profound decrease in O2 consumption allows the patient to survive with minimal blood flow
131
Q

Target temperature prior to circulatory arrest

A

15-17 C (the longer the operation, the colder the pt needs to be)

132
Q

How do you use the EEG to monitor hypothermia?

A

Once the EEG is isoelectric (15-20C nasopharygeal), the pt is cooled for 10 minutes before DHCA is initiated to ensure adequate, homogenous cooling of the brain

133
Q

How long is circulatory arrest safe at a temperature of 36, 32, 28, 24, 20 and 16C?

A

36: 1 min
32: 5 min
28: 10 min
24: 20 min
20: 30-40 min
16: 45-60 min

134
Q

What is the generally accepted time for circulatory arrest?

A

<60 minutes

Anything greater and most suffer from irreversible brain injury

135
Q

Who can tolerate longer periods of circulatory arrest?

A

Neonates and children

136
Q

Complications of DHCA

A
  1. Any complication of hypothermia (coagulopathy and profuse bleeding)
  2. Potential neurologic complications (too long, too rapid cooling, too repaid rewarming)
137
Q

What can happen with rapid cooling (<20 min) in DHCA?

A

-Lower neurodevelopmental outcome scores

138
Q

What can happen with rapid re-warming in DHCA?

A
  • Promotes systemic gas bubble formation, cerebral oxygen desaturation and uneven warming
  • Organ damage
  • Deleterious to neurologic outcomes
139
Q

What is the ideal speed of rewarming from DHCA?

A

<1C core temperature rise per 3 minutes of bypass time. Re-warming should end when nasopharyngeal temperature reaches 35C

140
Q

DHCA management

A
  1. Nasal temperature probe

2. Additional brain protection (ice, intermittent cerebral perfusion)

141
Q

What is retrograde cerebral perfusion?

A

The perfusionist can deliver cold blood to the head from the SVC

142
Q

What is antegrade cerebral perfusion?

A

R axillary artery perfusion can perfuse the lower extremities with the regular arterial cannula and the head with the extra perfusion line

143
Q

Disadvantage of antegrade cerebral perfusion compared to DHCA

A

Placement of an extra perfusion line can increase risk of stroke

144
Q

Near infared spectroscopy to measure O2 saturation in cerebral vessels

A

Cerebral oximeter (rSO2)

145
Q

Normal rSO2 value

A

60-80%

The cerebral vascular bed is 75% venous and 25% arterial

146
Q

What indicates that cerebral perfusion has decreased?

A

A low rSO2 value

147
Q

Applications for cerebral oximetry

A
  1. Heart surgery

2. Sitting position/beach chair surgery

148
Q

When should the anesthetist intervene with rSO2 monitoring?

A
  1. An rSO2 value less than 50%
  2. A greater than 20% drop from the individual baseline rSO2
  3. A difference of >30% from the L to R hemispheres
    * <45% absolute or >25% declines results in poor neurologic outcomes
149
Q

Factors that can decrease rSO2 values

A
  1. Decrease in cerebral blood flow (hypotension, dec CO, hyperventilation)
  2. Hypoxemia
  3. Anemia (due to 75% venous)
  4. Mechanical disturbances
150
Q

How can you increase cerebral SpO2?

A
  1. Increase cerebral perfusion pressure (MAP-ICP)
  2. Inc cerebral blood flow (inc PaCO2 by dec minute ventilation, NTG?)
  3. Inc FiO2
  4. Inc CO
  5. Inc Hct
  6. Dec cerebral metabolism (inc anesthetic or dec temperature)
151
Q

Normal PT (prothrombin time)

A

12-15 seconds

152
Q

Normal PTT (partial thromboplastin time)

A

25-40 seconds

153
Q

Normal INR

A

0.9-1.1

154
Q

How does unfractioned heparin work?

A

Binds and enhances the activity of antithrombin III 1000 fold

155
Q

Does heparin affect the intrinsic or extrinsic pathway?

A

Intrinsic

156
Q

What drug reverses heparin?

A

Protamine

157
Q

Can you administer heparin from a peripheral IV for a bypass?

A

No, you must administer it through a central line

158
Q

What is the heparin dose for standard CPB, and when is it dosed?

A

300-400 units/kg dosed just prior to aortic cannulation

159
Q

Used to assess coagulation in the cardiac OR when heparin is given

A

Activated Clotting Time (ACT)

160
Q

Normal ACT

A

100-150 seconds

161
Q

Goal ACT required prior to going on pump for cardiac surgery

A

> 450 seconds

162
Q

When a patient’s immune system develops antibodies against heparin

A

Heparin induced thrombocytopenia

163
Q

What does HIT cause?

A

Thrombocytopenia (low platelet count) and thrombosis

164
Q

HIT occurs with what types of heparin?

A

Standard heparin and (to a lesser extent) with fractioned heparin

165
Q

What is antithrombin III deficiency?

A
  • Low levels of AT-III, shows resistance to heparin

- can be inherited or acquired

166
Q

How do you manage antithrombin III deficiency?

A
  1. Replace the AT-III

2. Administer FFP

167
Q

Most common example of fractioned (LMW) heparin

A

Lovenox (enoxaparin)

168
Q

How is Lovenox different from standard heparin?

A
  1. It is dosed subQ
  2. Longer lasting (12-24 hrs)
  3. Does not affect/prolong PTT as much (used anti-Xa assay)
  4. Not reversed as reliably with protamine
169
Q

How does coumadin work?

A

Vitamin K antagonist that affects the extrinsic pathway

170
Q

How is coumadin dosed?

A

PO

171
Q

What test does coumadin affect?

A

PT and INR (extrinsic)

172
Q

What can reverse coumadin effects?

A
  1. FFP

2. Vitamin K

173
Q

How long does Plavix (clopidogrel) last?

A

5-7 days

174
Q

How is plavix dosed?

A

PO

175
Q

How is plavix reversed?

A

Platelets over a long period of time

176
Q

When should ASA be discontinued prior to elective operations?

A

7 days prior

177
Q

What is the recommendation for pts that underwent balloon angioplasty for managing dual antiplatelet therapy?

A

Dual antiplatelet therapy is required for 14 days

178
Q

Recommendation for dual antiplatelet therapy for bare metal stent nonurgently

A

DAT required for 1 month

  • elective surgery should be delayed for 1 month
  • Urgent surgery may continue with ASA but not plavix
179
Q

Recommendation for dual antiplatelet therapy for bare metal stent urgently

A

DAT required for 1 year

  • Elective surgery delayed for 1 year
  • Urgent surgery continue wtih ASA and not plavix
180
Q

Recommendation for antiplatelet therapy for drug-eluting stent, non urgently

A

DAT required for 6 months

  • elective surgery should be delayed for 6 months
  • urgent surgery may continue with ASA and not plavix
181
Q

Recommendation for antiplatelet therapy for drug-eluting stent, urgently

A

DAT required for 1 year

  • elective surgery should be delayed for 1 year
  • urgent surgery may continue with ASA and not plavix
182
Q

How does Xarelto work?

A

PO direct factor Xa inhibitor, causes anticoagulation by binding factor Xa

183
Q

How is Xarelto (rivaroxiban) reversed?

A

Andexxa

184
Q

When should Xarelto be discontinued prior to surgery?

A

24 hours

185
Q

How does Eliquis (apixaban) work?

A

Direct factor Xa inhibitor

186
Q

How is eliquis reversed?

A

Andexxa

187
Q

When should eliquis be discontinued prior to elective surgery?

A

48 hours

188
Q

Thrombolytic drugs

A

rtPA, Streptokinase, Urokinase

189
Q

When should thrombolytics be discontinued prior to elective surgery?

A

10 days

190
Q

When is a direct thrombin inhibitor used?

A

For anticoagulation in cardiac surgery in pts that cannot receive Heparin due to HIT
-Argatroban

191
Q

When is protamine dosed?

A

After the pt is taken off CPB, given peripherally and slowly over 10 min

192
Q

What is the dose of protamine?

A

1 mg protamine per 100 units of heparin

193
Q

What is the mechanism of protamine?

A

Binds to heparin directly

-Has anticoagulation properties when given by itself

194
Q

Adverse effects of protamine

A
  1. Hypotension
  2. Anaphylactoid reactions (with rapid or central administration)
  3. Possible catastropic pulmonary vasoconstriction
195
Q

What is prothrombin complex concentrate (PCC)?

A
  • Contains vitamin K dependent clotting factors (II, VII, IX, X)
  • Used to treat life threatening hemorrhage in unstable patients
  • Can be given as alternative to FFP as part of a massive hemorrhage protocol
  • Concentrated extract from FFP
196
Q

Each vial of PCC contains the same amount of factor IX that would be found in ___ units of FFP

A

2 units

197
Q

Advantages of PCC

A
  1. Twice as fast as FFP
  2. Single dose every 24 hours, much less volume required
  3. Half the adverse effects of FFP
  4. Faster prep time (does not require thawing)
198
Q

Disadvantages of PCC

A
  1. Up to 20x more expensive than FFP

2. Shorter acting than FFP

Methods of Anesthesia (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions