4 surgical techniques for Cardiac operations
- On pump with an arrested heart
- sometimes arresting the heart is required and sometimes the surgeon will arrest the heart if its not required
- On pump with a beating heart
- pump assisted beating heart surgery
- can be performed with total or partial bypass
- Off pump
- patient is not put on the bypass machine
- heart stays beating
- new technique available for valve repair/ replacement
Anesthetic Management for On PUMP cardiac surgery with an Arrested heart:
What are the first two steps prior to incision?
- Cardiac Induction
Cardiac Induction On pump:
Large doses of this drug is rarely used for induction?
What are 3 alternative techniques for achieving a cardiac induction?
1. high doses of versed (5 mg) and fentanyl (250 mcg)
- produces less hypotension on induction
- causes adrenal suppression
- linked to worse postoperative outcomes
- small propofol dose followed by inhalation induction with bag mask ventilation
- slower onset of hypotension after induction
What is an advantage of using etomidate on cardiac induction?
produces less hypotension on induction
what is a disadvantage of using etomidate on cardiac induction?
causes adrenal suppression and may be linked to worse postop outcomes
on Cardiac induction it is common to give the drugs (slow/fast) and use the _____ _____ pressure as a guide for when to intubate
on cardiac induction, intubation is indicated once the induction drugs have lowered the BP to an acceptable level so as not to produce ______ from intubation
first B in BOBCAT
O in BOBCAT
insertion and removal
-possibly reinsert the OG at the end of the case
where should you avoid placing the OG in cardiac patients? why?
in the nare
-patient is heparinzed
2nd B in BOBCAT
BIS monitor placement
C in BOBCAT
Central line placement
A in BOBCAT
When is Amicar bolused?
after central line placement
What is the dose of the Amicar bolus?
What do you follow the bolus with?
followed by 1g/hour infusion
T in BOBCAT
what is the most common anti-fibrinolytic drug used in cardiopulmonary bypass?
Amicar (epsilon-aminocaproic acid)
What drug may be used as an alternative to Amicar?
Why are anti-fibrinolytic used in cardiac surgery?
They counteract the damaging effects of the bypass machine on the blood and reduce bleeding post-cardiopulmonary bypasss by inhibiting fibrinolysis
Why is a TEE placed during cardiac surgery?
Regional wall motion abnormalities on TEE have been shown to be the earliest and most sensitive sign to detect myocardial ischemia
What is the first step of cardiac surgery after induction and BOBCAT?
Leg incision to harvest the saphenous vein
- long step and can take up to an hour
- only applicable if doing a CABG
Which type of procedures do not require the harvesting of the saphenous vein?
What is the next step after harvesting the saphenous vein (if needed)
Sternal incision and sternotomy
What patient consideration should you try to avoid during the sternal incision/sternotomy?
-intense stimulation during this period
What are 2 of the most popular drug options for preventing hypertension during a sternal incision/sternotomy?
fentanyl or nitroglycerin
What are the 2 steps the anesthetist MUST do during the sternal incision/ sternotomy?
- turn off the ventilator
- remove the breathing bag from the circuit
- do not want the lungs to inflate while the saw is in the chest
What step comes after the sternal incision?
After sternal retraction, what happens to intrathoracic pressure?
becomes the same as atmospheric pressure
-not negative anymore
What changes does the increase in intrathoracic pressure cause to the patient?
an (increase/decrease) in venous return
an (increase/decrease) in cardiac output
decrease in venous return
decrease in cardiac output
During sternal retraction, the retractors can cause compression of the ______ artery which may cause (right/left) radial artery arterial lines to show a falsely ____ number
After sternal retraction, what is the next step?
Harvesting the LIMA
-only applicable for CABG
3 considerations when the surgeon is harvesting the LIMA:
- There is (less/more) stimulation during this period
- ____ _____ can get in the surgeon’s way
- (right/left) sided radial arterial lines may not function during LIMA dissection due to compression of the _____ artery from sternal retraction
-same may be true with right sided arterial line and RIMA
What is the main task of the anesthetist while the surgeon is harvesting the LIMA?
Decreasing the patients tidal volume to keep the lungs out of the surgeons way
-may need to increase respirations to keep minute ventilation the same
What is the next step after the LIMA is harvested?
Opening of the pericardium
What response may the patient elicit when the pericardium is opened?
-the nerves innervating the pericardium are derived from the vagus and the phrenic
Why will the surgeon choose not to close the pericardium at the end of the surgery?
higher chance of cardiac tamponade
Why must the LIMA be harvested BEFORE the pericardium is opened?
because the pericardium is sewn to the chest wall and would be in the way
When must heparin be administered?
prior to aortic cannulation
-right after the pericardium is opened
____ minutes after heparin is given, ____ mL of blood sample is drawn from the arterial line to check the _____
if the ACT is _____, the patient is ready for bypass
if the ACT is _____, additional heparin may need to be given
What is the next step right after heparin is given?
a consideration during aortic cannulation is that it can lead to _____ ______
(venous/arterial) cannulation is established before (venous/arterial) cannulation to allow rapid intravascular volume or blood rescusitation if necessary
What is the main task of the anesthetist during arterial cannulation?
Lower the systolic BP to 90-100 mmHg prior to cannulation to decrease the risk of disection
What step comes right after the arterial cannulation?
Venous cannulation and opening of the venous reservoir
venous cannulation usually occurs in the _____ _____ _____
right atrial appendage (RAE)
When is the patient considered “on pump”?
once the venous reservoir is opened
What are the 4 tasks of the Anesthetist at the ONSET of full bypass
- Turn off the ventilator and the vaporizer off
- only during full bypass
- Measure pre-bypass urine output
- allows the anesthetist and perfusionist to know how much urine is produced on pump
- Put the monitor in “bypass” mode
- will turn off the alarms
- Put vasoactive infusions on standby
- can run if the perfusionist requests to help control BP
What are the 2 drugs the anesthetist should keep infusing at the onset of bypass?
What is the optimal MAP while a patient is on bypass?
What button do you hit on the monitor to change the mode from “open heart” off pump to “bypass” while on pump
After the venous reservoir is opened and the patient has gone “on pump” what is the next step?
Placement of the cardioplegia catheter
________ cardioplegia is usually administered via the ____ _____
After the cardioplegia catheter is placed, what is the next step?
aortic cross clamp placement
-strain on the heart is minimized because the heart is empty
What happens after the cross clamp is placed?
the heart is arrested with cardioplegia
-typically given intermittently every 20-30 minutes but may be given continuously
Once the cross clamp is placed, the surgeon can now do what?
repair the CABG or valve
-patient is typically cooled to a degree at this point
What is the indication that the surgeon is almost done repairing the heart?
When the perfusionist starts rewarming the patient
What risk increases during rewarming of the patient
-lose the anesthetic effects of hypothermia
What are 3 drugs the anesthetist will possibly dose in the rewarming phase?
- increased risk of awareness
- Antiarrhythmics (magnesium, amiodarone, lidocaine)
- help decrease the chance of the heart going into V-fib/Vt-tach when the heart resumes electrical activity
- helps to kick start the heart when it starts beating again
What is the first step to coming off bypass once the patient starts re-warming?
The perfusionist refills the heart with blood by partially closing the venous reservoir
Once the heart is filled back up with blood from the venous reservoir, what does the surgeon do next?
Looks for and removes any air bubbles
-especially in surgeries where the aorta or myocardium was opened
Once all the air bubbles are removed, what happens next?
the aortic cross clamp is removed
after aortic cross clamp removal, the blood from the _____ _____ will rush into the heart and flush out all the _______ and allow the heart to start beating again
As soon as the cardioplegia washes out, the heart will usually go into what 2 rhythms
2. Vtach, Vfib
If the heart goes into Vtach/Vfib, the surgeon will apply a _______ shock to the heart
Once a re-establishment of an effective sinus rhythm is established, the heart may not initially beat effectively.
What are 2 things the anesthetist can do to help the heart beat more effectively?
- Give inotropic drugs
- calcium, epi, milrinone, dobutamine
- have the surgeon place temporary pacing wires
In order to keep oxygen demand low while allowing the heart to recover, some recommend having the heart (full/empty) for _____ minutes prior to filling the heart with blood again
What amperage and rate should the external pacemaker settings be?
Once the patient has a heart beat and is oxygenating their own blood, what should the anesthetist do?
Turn back on the ventilator and and Isoflurane
Once the anesthetist turns the ventilator and volatile agent back on coming off bypass, what does the perfusionist do?
completely close the venous reservoir so that all the blood is flowing through the patient’s heart and lungs
After closure of the venous cannula, what is the next step?
removal of venous and aortic cannulas
-patient is now “off pump”
Once the patient is officially off bypass, what step comes next?
Reversal of Heparin Anticoagulation
What are the 2 drug options for the reversal of Heparin anticoagulation?
2. DDAVP (desmopressin)
What is the primary drug used to reverse anticoagulation after cardiopulmonary bypass?
If the patient is still bleeding more than expected after administer of Protamine, what else can be administered?
-will cause clotting factor release and can promote coagulation
Heparin reversal occurs (prior/after) chest closure
-surgeon will not close the chest until the bleeding is controlled
What is administered after protamine?
Cell saver blood
What is the reason cell saver blood is given after protamine?
Takes time for the blood to be centrifuged and by the time the cell saver blood is ready, protamine will have already been administered
After the cell save blood is given, what should the anesthetist do next?
Start a sedation drip for transport
What are 2 options for a sedation drip for transport?
- Propofol (20-50 mcg/kg/min)
- most common
is the sedation drip started before or after closure?
-the infusion runs at a slow rate and could take several minutes for the drug to reach the patient after the time it starts running
What is the infusion rate for propofol sedation drip for transport post cardiac surgery?
After the sedation drip is started, what comes next?
the chest is closed and a chest drainage tube is placed
After the chest is closed and chest drainage is placed, what is the next step?
transport the patient to the ICU with a transport monitor
What 2 things should the anesthetist remember to take while transferring the patient to the ICU post cardiac surgery?
laryngoscope and vasoactive meds
If a patient requires a 2nd heart surgery, they may require a 2nd sternotomy. Why may this be problematic?
Risk of uncontrollable hemorrhage as the heart and major vessels may be injured
-after a primary sternotomy, heart structures develop post-op adhesions with the back of the sternum
What are 3 things necessary for management of a redo sternotomy?
- preparation for hemorrhage by having blood and blood tubing available
- have defibrillator pads placed BEFORE induction
- will take longer than a primary sternotomy and ventilation (lung expansion) is necessary
- anesthetists will gently hand ventilate to prevent the lungs from inflating too much (decreases the chance of lung injury)
What percent of patients will require surgical re-exploration?
how much blood output will MOST patients have in the chest tube after cardiac surgery
What amount of chest tube drainage usually prompts immediate surgical intervention?
Chest tube drainage exceeding 8-10 mL/kg/hr
What are 2 places that ischemia could have come from in patients who have heart surgery?
- coronary artery blockage
2. less perfusion during bypass
What is reperfusion and what are 2 ways in which it can happen?
- reperfusion injury can cause further injury to the heart
1. an occluded coronary artery being opened up
2. re-establishment of perfusion after being weaned from bypass
_________ of previously ischemic myocardium has been shown to cause further injury that is expressed as contractile dysfunction, infarction…and arrhythmias. Reperfusion injury may contribute significantly to the morbidity and mortality after cardiac surgery
What are 2 causes of reperfusion injury?
- accumulation of intracellular calcium
- prolonged ischemia period
- the greater the severity of ischemia, the greater the reperfusion injury
according to the BOOK, when should calcium be administered in cardiac surgery?
Only after the heart has been reperfused (15 minutes after aortic cross-clamp release)
In the CLINICAL setting, when is calcium usually administered?
during the rewarming phase to ensure the heart is beating effectively before the aortic cross clamp is taken off
this inhalation agent is avoided during bypass surgery
3 reasons why nitrous oxide is avoided during bypass surgery
- because of its potential to expand air bubbles
- it can increase pulmonary vascular resistance and elevate PA pressures
- worsens right heart output
- many patients require a higher FiO2 during this period
When are Off Pump cardiac procedures not an option?
- when the heart needs to be arrested
- the heart needs to be drained of blood
- not feasible with open valve repair
When is Off Pump surgery most common?
During CABG the surgeon must lift the heart to get to the coronary arteries. This irritates the heart and can lead to what 3 things
- profound decrease in EF and cardiac output
4 advantages of off pump procedures
- Patients may experience a faster recovery and shorter hospital stay
- post operative neurological deficiencies appear to be decreased
- less manipulation of the aorta
- better renal, pulmonary, and myocardial protection
- physiologic cardiac perfusion is maintained throughout the operation
4 disadvantages of off pump procedures
- distal anastomosis may not be as good as those performed on pump
- leads to increased platelet deposition at the anastomosis site, faster re-occlusion of the bypass graft (graft thrombosis), and chance of needing subsequent vascularization
- higher degree of hemodynamic instability because of decreased cardiac output, hypotension, and arrhythmias
- total number of grafts being performed may be less on these patients, resulting in “under vascularization”
- surgeon more reluctant to perform as many grafts than when on pump
- There is a steep learning curve associated with performing “off pump” bypass surgery and can result in worse outcomes
What are the 3 procedures where off pump technique is most common?
- Coronary Artery Bypass Graft (CABG)
- Transmyocardial Laser Revascularization (TMR)
- Endovascular valve repair
severely stenosed arteries are more likely to have _______ flow
vessels that are proximally diseased or less severely stenosed can result in severe _____ ______ and adverse ______ consequences
preoperatively the anesthetist should read the Cath report to assess the severity of ____ lesions
-so they know which vessels to expect the most hypotension with
more stenotic vessels have (better/worse) collateral circulation, so (less/more) hypotension is expected when the surgeon lifts the heart
less stenotic vessels have (better/worse) collateral circulation, so (less/more) hypotension is expected when the surgeon lifts the heart
-collateral circulation is under developed
proximal anastomosis are usually sewn into the aorta (before/after) the distal anastomoses
At what pressure should the anesthetist keep the blood pressure during the proximal anastomosis?
under 100 mmHg systolic
-to prevent aortic dissection
distal anastomoses are sewn in (before/after) the proximally anastomoses
During the distal anastomosis, the surgeon must apply suction to the heart. What 2 types of drugs are needed during this to maintain normotension?
Vasopressors and inotropes
At what pressure should the anesthetist keep the blood pressure during the distal anastomosis?
normal BP with a MAP of 90-100 mmHg
-to maintain coronary perfusion
During Off Pump CABG management, what should the anesthetist administer after incision but before the surgeon lifts the heart?
- 2 liters crystalloid and 500 mL 5% Albumin
- prevents hypotension
- if the fluid is administered to early, the patient will pee it off
During Off Pump CABG management, what 3 drugs should the anesthetist dose prior to the surgeon lifting the heart
Amiodorone (150 mg)
-these drugs are antiarrythmics and decrease the patient going into arrhythmia when off pump equipment is used
-gives inotropic support and helps prevent hypotension when the heart is lifted
What 2 drugs are still administered in Off Pump CABG even though the bypass machine is not being used?
-may turn into a bypass surgery
When the Off Pump CABG technique fails because the patient will not tolerate it, what 2 other surgical options are available?
- place the patient on full bypass and arrest the heart
- requires aortic cross clamp and to restart the heart
- place the patient on full or partial bypass and leave the heart beating
- aka “pump assisted beating heart surgery”
- does not require an aortic cross clamp or to restart the heart
If the patient is placed on full bypass, the lungs (do/do not) need to be ventilated and volatile agent (does/ does not) need to be administered
If the patient is placed on partial bypass, the lungs (do/do not) need to be ventilated and volatile agent (does/does not) need to be administered
2 advantages to pump assisted beating heart surgery over Off pump
- reduce hypotension effects
- perfusion can control the patients BP
- offers better myocardial protection because there is less oxygen demand when the heart is beating in an empty state
What are 2 advantages to arresting the heart
- Lower oxygen demand
- easier for the surgeon
- can lead to a more complete heart repair
3 disadvantages to arresting the heart
- aortic cross clamp is placed
- higher risk of neurologic complications
- worse perfusion in CP cannulas
- leads to higher re-perfusion injury risk
- implementation of modest hypothermia to offset this which has its own compilations
- heart must be re-started
- leads to longer CPB times
- may require multiple defibrillation attempts
3 advantages to beating heart surgery (on or off pump)
- perfusion is better
- constant and physiologic
- less chance of reperfusion injury
- perfusion to other organs is better (kidneys)
- no need for hypothermia
- less neurologic risk
- aortic cross clamp is not placed
- the heart does not need to be restarted
- shorter bypass times if using on pump technique
3 disadvantages to beating heart surgery (on or off pump)
- heart has higher oxygen demand
- can be offset by better perfusion with beating heart
- higher risk of air and debris embolization
- no aortic cross clamp
- more challenging for the surgeon
- could lead to less complete surgical repair