On Pump vs. Off Pump Management for Open Heart Surgery Flashcards
what are the 4 types of surgical techniques for cardiac operations?
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)
List the Pump steps
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
what are the steps prior to incision
1 cardiac induction
2- BOBCAT
cardiac induction 3 options
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
BOBCAT
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
Amicar bolus at liberty vs lukes
liberty 5g
lukes 10g
amicar
antifibrinolytic to counteract damage done by bypass machine
what is the alternative to amicar
tranexamic acid
sternal incision and sternotomy considerations
avoid hypertension bc of intense stimulation, fent or NTG
What should the anesthetist do during sternal incision and sternotomy
turn off vent and remove breathing bag from circuit bc we want the lungs down
what happens to intrathoracic pressure during sternal retraction? what should we be concerned about?
intrathoracic pressure increases
venous return and cardiac output can decrease
what should we be concerned about for the retractor on the sternum?
could compress subclavian artery and cause right radial artery false low readings
harvesting LIMA considerations 3
less stimulation
lung expansion may get in the way
left sided radial arterial lines may not function due to compression
tasks during harvesting of the LIMA
decrease tidal volume (may need to increase RR for min vent)
when might the patient have a vagal response? why?
opening of the pericardium, pericardium is innervated by vagus and phrenic
do surgeons close the pericardium at end of surgery?
no, risk of cardiac tamponade
after the pericardium is opened what does the surgeon do?
sews it to the chest wall to get it out of the way
when do you give heparin
after pericardium opening and before aortic cannulation
what happens after you give heparin
1mL blood sample is drawn 3 min later
ACT >450 then ready
ACT <450 may need more heparin
aortic cannulation considerations
lead to possible aortic dissection
why is aortic cannulation before venous cannulation
incase you need rapid blood resuscitation
task during aortic cannulation
lower systolic pressure to 90-100 mmHg
where do you normally place the venous cannula
right atrial appendage (RAE)
pt is on pump after venous reservoir is opened
anesthetist task at the onset of bypass
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
what is the target MAP while on pump? why?
50-80mmHG
aortic dissection and cerebral hemorrhage likely with high MAPs
what is the usual way of cardioplegia
antegrade cardioplegia is administered via aortic root
arresting the heart with CP
typically given every 20-30 min but can be given continuously
when is the patient usually cooled?
when the CABG or valve repair is performed
what does perfusionist starting rewarming indicate?
surgeon almost done with repairing heart
risk for awareness increases
what are the possible drugs to dose during the rewarming phase
versed (increased awareness counteract)
antiarrhythmics (avoid vfib or vtach)
calcium (kick start heart)
when is looking for bubbles especially indicated?
operations where the myocardium or aorta was opened
when will the heart start beating again
when the aortic cross clamp is removed and the CP solution is flushed out
what are the two rhythms that the heart will usually go into?
bradycardia
vtach/vfib
when and how to defibrillate
if in vtach or vfib
apply 10-20J shock to heart
how can the anesthetist kick start the heart?
give inotrop (calcium, epi, milrinone) have surgeon place temporary pacing wires
what do some people recommend to keep oxygen demand low during recovery?
let heart beat in empty state for 20-30 min prior to filling
pacing during heart surgery
external pacemaker settings
energy 20mA
rate 80-100bpm
what are the options for reversal of anticoagulation?
protamine
DDAVP (desmopressin)
when does heparin reversal occur
prior to chest closure bc surgeon wont close unless bleeding is under control
why do you give cell saver after protamine?
takes time for the blood to be centrifuged
what are the options for sedation during transport
propofol (20-50mcg/kg/min) (most common)
precedex
why is a sedation drip started prior to chest closure?
because it is a slow rate and could take up to 20 min for the drug to start getting to the pt
what should you have when transporting to the ICU
transport monitor
laryngoscope
vasoactive drugs
redo sternotomy
could be problematic bc heart structures adhere to the back of the sternum
high risk of uncontrollable hemorrhage
management steps for a redo sternotomy
have blood and blood tubing available
have defibrillator pads placed
ventilation is necessary bc it will take longer (hand ventilate)
post op bleeding % of pts
2-4% of pts will have post op bleeding
most common blood output through chest tube post surgery
0.5-1mL/kg/hr
what blood output through chest tube post surgery requires immediate surgical intervention??
8-10mL/kg/hr
reperfusion injury
when the heart gets reperfused there is a chance that further injury can occur; contractile dysfunction, infarction, arrhythmias
ischemia causes during heart surgery
coronary arter blockage
less perfusion during bypass
what can reperfusion refer to?
occluded coronary artery opened up
reestablishment of perfusion after bypass
2 causes of reperfusion injury
accumulation of intracellular calcium (calcium should be administered 15 min after aortic cross clamp comes off)
prolonged ischemia period
Why is nitrous oxide avoided during bypass surgery
potential to expand air bubbles
increase pulmonary vascular resistance and elevate PA pressures
patients require higher FiO2 during bypass
what does off pump mean
no bypass machine
heart stays beating
when is off pump NOT and option?
heart needs to be arrested
heart needs to be drained of blood
surgical technique for off pump CABG
must lift heart occasionally and could lead to:
arrhythmias
decreased CO or EF
hypotension
problem of off pump cardiac procedures
more difficult for surgeon
more difficult for anesthetist
off pump advantages 3
faster recovery and shorter hosp stay
post op neuologic deficiencies decreased (less aorta manipulation)
better protection of renal, pulmonary and myocardial tissue
disadvantages to off pump CABG 4
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
common procedures for off pump
CABG
transmyocardial laser revascularization
endovascular valve repair
collateral circulation
more distal or severely stenosed arteries are more likely to have collateral flow
preoperative cath report
we should look at this to locate and assess the severity of coronary lesions so we know which ones are being bypassed
more stenotic vessels
more collateral circ
less hypotension expected
less stenotic vessels
undeveloped collateral circ
more hypotension expected
when are proximal anastomosis sewn on and what should we do?
after the distals
keep systolic BP below 100mmHg
when are distal anastomosis sewn on and what should we do
before proximals
vasopressors and inotropes usually required to maintain normotension MAP of 90-100
off pump CABG management
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
how to prepare to prevent hypotension, arrhythmias, and decreased CO
administer fluid bolus after incision prior to lifting heart
dosing antiarrhytmics prior to incision
dose 1 g calcium prior to lifting heart for distals
two antiarrhythmics to give off pump management
magnesium 1-2 g
amiodarone 150mg
options for when off pump fails
place pt on full bypass and arrest heart
place pt on full or patial bypass and leave heart beating
main thing to remember for full vs partial bypass
full- no ventilation needed
partial- ventilation and volatile agent needed
what are the two benefits of pump assisted beating heart surgery over off pump
hypotension less likely
better myocardial protection
advantages to arresting the heart
lower oxygen demand
easier for surgeon
disadvantages to arresting the heart
aortic cross clamp is placed
worse perfusion (reperfusion injury, hypothermia)
heart must be restarted
advantages to beating heart cardiac surgery
perfusion better
less neurologic risk (less reperfusion injury, ischemia reduced)
heart doesnt need to be restarted
disadvantages to beating heart cardiac surgery
higher oxygen demand of heart
higher risk of air and debris embolization bc no cross clamp
more challenging for surgeon
