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Methods of Anesthesia I > On Pump vs. Off Pump Management for Open Heart Surgery > Flashcards

On Pump vs. Off Pump Management for Open Heart Surgery Flashcards

1
Q

what are the 4 types of surgical techniques for cardiac operations?

A

on pump with arrested heart (could be required or preferred)
on pump with beating heart (“pump assisted beating heart surgery”)
off pump (no bypass machine)
endovascular (new for valve repair or replacement)

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2
Q

List the Pump steps

A

1- cardiac induction, 2- BOBCAT, 3- leg incision to harvest saphenous, 4- sternal incision and sternotomy, 5- sternal retraction, 6- harvest LIMA, 7/8- open pericardium and administer heparin, 9- aortic cannulation, 10- venous cannula and open reservoir, 11- CP catheter inserted, 12- aortic cross clamp placed, 13- heart arrested with CP, 14- CABG or valve repair performed, 15- rewarming phase
16- perfusionist partially closes venous reservoir, 17- surgeon removes air from heart, 18- cross clamp removed, 19- heart resumes electrical activity, 20- defibrillation (maybe), 21- NSR established, 22- turn of volatile agent and ventilator, 23- venous reservoir completely closed, 24- venous and aortic cannula removed, 25- reversal of anticoagulant, 26/27- cell saver given and prepare sedation drip for transport, 28- chest closed and chest tube placed, 29- transport ICU with monitors

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3
Q

what are the steps prior to incision

A

1 cardiac induction

2- BOBCAT

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4
Q

cardiac induction 3 options

A

1- higher versed (5mg) and fent 250mcg
2- etomidate (debatable bc adrenal suppression)
3- smaller prop dose and followed by inhalational induction
give drugs more slowly and use aline to guide when to intubate

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5
Q

BOBCAT

A 
baseline labs/ACT
OG insertion and removal
BIS monitor placement
Central line placement
Amicar bolus followed by 1g/hr infusion
TEE regional wall motion abnormalities for ischemia
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6
Q

Amicar bolus at liberty vs lukes

A

liberty 5g

lukes 10g

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7
Q

amicar

A

antifibrinolytic to counteract damage done by bypass machine

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8
Q

what is the alternative to amicar

A

tranexamic acid

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9
Q

sternal incision and sternotomy considerations

A

avoid hypertension bc of intense stimulation, fent or NTG

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10
Q

What should the anesthetist do during sternal incision and sternotomy

A

turn off vent and remove breathing bag from circuit bc we want the lungs down

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11
Q

what happens to intrathoracic pressure during sternal retraction? what should we be concerned about?

A

intrathoracic pressure increases

venous return and cardiac output can decrease

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12
Q

what should we be concerned about for the retractor on the sternum?

A

could compress subclavian artery and cause right radial artery false low readings

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13
Q

harvesting LIMA considerations 3

A

less stimulation
lung expansion may get in the way
left sided radial arterial lines may not function due to compression

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14
Q

tasks during harvesting of the LIMA

A

decrease tidal volume (may need to increase RR for min vent)

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15
Q

when might the patient have a vagal response? why?

A

opening of the pericardium, pericardium is innervated by vagus and phrenic

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16
Q

do surgeons close the pericardium at end of surgery?

A

no, risk of cardiac tamponade

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17
Q

after the pericardium is opened what does the surgeon do?

A

sews it to the chest wall to get it out of the way

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18
Q

when do you give heparin

A

after pericardium opening and before aortic cannulation

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19
Q

what happens after you give heparin

A

1mL blood sample is drawn 3 min later
ACT >450 then ready
ACT <450 may need more heparin

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20
Q

aortic cannulation considerations

A

lead to possible aortic dissection

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21
Q

why is aortic cannulation before venous cannulation

A

incase you need rapid blood resuscitation

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22
Q

task during aortic cannulation

A

lower systolic pressure to 90-100 mmHg

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23
Q

where do you normally place the venous cannula

A

right atrial appendage (RAE)

pt is on pump after venous reservoir is opened

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24
Q

anesthetist task at the onset of bypass

A 
1 turn off ventilator and vaporizer
2 put vasoactive infusions on standby (amicar and insulin continued)
3 measure pre bypass urine output
4 chart BIS, MAP, and temp
5 put monitor on bypass mode
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25
Q

what is the target MAP while on pump? why?

A

50-80mmHG

aortic dissection and cerebral hemorrhage likely with high MAPs

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26
Q

what is the usual way of cardioplegia

A

antegrade cardioplegia is administered via aortic root

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27
Q

arresting the heart with CP

A

typically given every 20-30 min but can be given continuously

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28
Q

when is the patient usually cooled?

A

when the CABG or valve repair is performed

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29
Q

what does perfusionist starting rewarming indicate?

A

surgeon almost done with repairing heart

risk for awareness increases

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30
Q

what are the possible drugs to dose during the rewarming phase

A

versed (increased awareness counteract)
antiarrhythmics (avoid vfib or vtach)
calcium (kick start heart)

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31
Q

when is looking for bubbles especially indicated?

A

operations where the myocardium or aorta was opened

32
Q

when will the heart start beating again

A

when the aortic cross clamp is removed and the CP solution is flushed out

33
Q

what are the two rhythms that the heart will usually go into?

A

bradycardia

vtach/vfib

34
Q

when and how to defibrillate

A

if in vtach or vfib

apply 10-20J shock to heart

35
Q

how can the anesthetist kick start the heart?

A 
give inotrop (calcium, epi, milrinone)
have surgeon place temporary pacing wires
36
Q

what do some people recommend to keep oxygen demand low during recovery?

A

let heart beat in empty state for 20-30 min prior to filling

37
Q

pacing during heart surgery

A

external pacemaker settings
energy 20mA
rate 80-100bpm

38
Q

what are the options for reversal of anticoagulation?

A

protamine

DDAVP (desmopressin)

39
Q

when does heparin reversal occur

A

prior to chest closure bc surgeon wont close unless bleeding is under control

40
Q

why do you give cell saver after protamine?

A

takes time for the blood to be centrifuged

41
Q

what are the options for sedation during transport

A

propofol (20-50mcg/kg/min) (most common)

precedex

42
Q

why is a sedation drip started prior to chest closure?

A

because it is a slow rate and could take up to 20 min for the drug to start getting to the pt

43
Q

what should you have when transporting to the ICU

A

transport monitor
laryngoscope
vasoactive drugs

44
Q

redo sternotomy

A

could be problematic bc heart structures adhere to the back of the sternum
high risk of uncontrollable hemorrhage

45
Q

management steps for a redo sternotomy

A

have blood and blood tubing available
have defibrillator pads placed
ventilation is necessary bc it will take longer (hand ventilate)

46
Q

post op bleeding % of pts

A

2-4% of pts will have post op bleeding

47
Q

most common blood output through chest tube post surgery

A

0.5-1mL/kg/hr

48
Q

what blood output through chest tube post surgery requires immediate surgical intervention??

A

8-10mL/kg/hr

49
Q

reperfusion injury

A

when the heart gets reperfused there is a chance that further injury can occur; contractile dysfunction, infarction, arrhythmias

50
Q

ischemia causes during heart surgery

A

coronary arter blockage

less perfusion during bypass

51
Q

what can reperfusion refer to?

A

occluded coronary artery opened up

reestablishment of perfusion after bypass

52
Q

2 causes of reperfusion injury

A

accumulation of intracellular calcium (calcium should be administered 15 min after aortic cross clamp comes off)
prolonged ischemia period

53
Q

Why is nitrous oxide avoided during bypass surgery

A

potential to expand air bubbles
increase pulmonary vascular resistance and elevate PA pressures
patients require higher FiO2 during bypass

54
Q

what does off pump mean

A

no bypass machine

heart stays beating

55
Q

when is off pump NOT and option?

A

heart needs to be arrested

heart needs to be drained of blood

56
Q

surgical technique for off pump CABG

A

must lift heart occasionally and could lead to:
arrhythmias
decreased CO or EF
hypotension

57
Q

problem of off pump cardiac procedures

A

more difficult for surgeon

more difficult for anesthetist

58
Q

off pump advantages 3

A

faster recovery and shorter hosp stay
post op neuologic deficiencies decreased (less aorta manipulation)
better protection of renal, pulmonary and myocardial tissue

59
Q

disadvantages to off pump CABG 4

A

1 higher degree of hemodynamic instability
2 distal anastomosis may not be as good as when on pump
3 total number of grafts being performed may be less resulting in under vascularization
4 steep learning curve which can result in worse outcomes

60
Q

common procedures for off pump

A

CABG
transmyocardial laser revascularization
endovascular valve repair

61
Q

collateral circulation

A

more distal or severely stenosed arteries are more likely to have collateral flow

62
Q

preoperative cath report

A

we should look at this to locate and assess the severity of coronary lesions so we know which ones are being bypassed

63
Q

more stenotic vessels

A

more collateral circ

less hypotension expected

64
Q

less stenotic vessels

A

undeveloped collateral circ

more hypotension expected

65
Q

when are proximal anastomosis sewn on and what should we do?

A

after the distals

keep systolic BP below 100mmHg

66
Q

when are distal anastomosis sewn on and what should we do

A

before proximals

vasopressors and inotropes usually required to maintain normotension MAP of 90-100

67
Q

off pump CABG management

A

1- prepare to prevent hypotension, arrhythmias, decreased CO
2- doses amicar even though the CPB machine isnt used
3- heparin also administered but the dose differs
4- anesthetist maintains BP in correct range for proximal or distals

68
Q

how to prepare to prevent hypotension, arrhythmias, and decreased CO

A

administer fluid bolus after incision prior to lifting heart
dosing antiarrhytmics prior to incision
dose 1 g calcium prior to lifting heart for distals

69
Q

two antiarrhythmics to give off pump management

A

magnesium 1-2 g

amiodarone 150mg

70
Q

options for when off pump fails

A

place pt on full bypass and arrest heart

place pt on full or patial bypass and leave heart beating

71
Q

main thing to remember for full vs partial bypass

A

full- no ventilation needed

partial- ventilation and volatile agent needed

72
Q

what are the two benefits of pump assisted beating heart surgery over off pump

A

hypotension less likely

better myocardial protection

73
Q

advantages to arresting the heart

A

lower oxygen demand

easier for surgeon

74
Q

disadvantages to arresting the heart

A

aortic cross clamp is placed
worse perfusion (reperfusion injury, hypothermia)
heart must be restarted

75
Q

advantages to beating heart cardiac surgery

A

perfusion better
less neurologic risk (less reperfusion injury, ischemia reduced)
heart doesnt need to be restarted

76
Q

disadvantages to beating heart cardiac surgery

A

higher oxygen demand of heart
higher risk of air and debris embolization bc no cross clamp
more challenging for surgeon

Methods of Anesthesia I (10 decks)

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