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Methods of Anesthesia I > "On Pump" vs. "Off Pump" Management > Flashcards

"On Pump" vs. "Off Pump" Management Flashcards

1
Q

What are different Surgical Techniques for Cardiac Operations? (4)

A
  1. On pump with arrested heart
  2. On pump with beating heart
  3. Off pump
  4. Endovascular
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2
Q

Anesthetic Management for a Traditional On Pump Cardiac Surgery with an Arrested Heart

Steps Prior to Incision (1-2)

A
  1. Cardiac induction
    - Higher versed (5mg)/fentanyl (250mcg)
    - Etomidate (beware of adrenal suppression)
    - Small propofol dose followed by mask ventilation
  2. BOBCAT
    - Baseline labs/ACT
    - OG insertion and removal
    - BIS monitor placment
    - Central line placement
    - Amicar bolus, followed by 1g/hr infusion (5-10g bolus dose after central line placement)
    - TEE monitoring
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3
Q

What is Amicar, and what is it used for?

A
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4
Q

What is the purpose of TEE monitoring?

A
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5
Q

Anesthetic Management for a Traditional On Pump Cardiac Surgery with an Arrested Heart

Steps From Incision Up To Cardiopulmonary Bypass (3-10)

A
  1. Leg Incision to Harvest the Saphenous Vein (only if CABG)
  2. Sternal Incision and Sternotomy
    - Avoid hypertension (use of fentanyl and NTG)
    - Turn off the vent and remove breathing bag from ventilator
  3. Sternal Retraction
    - Intrathoracic pressure is now equal to atmospheric (This “increase” in intrathoracic pressure should cause a decrease in venous return and cardiac output )
  4. Harvesting the LIMA (only if CABG)
    - Decrease tidal volume to keep lungs out of surgeons view (May need to increase the RR to keep minute ventilation normal)

7/8. Opening the Pericardium
-May see vagal stimulation

7/8. Heparin Administration

  • Heparin must be administered prior to aortic cannulation
  • A 1mL blood sample is drawn from the arterial line 3 minutes later
  • If ACT>450, patient is ready for bypass
  • If ACT<450, patient may need more heparin
  1. Aortic Cannulation
    - The anesthetist should lower the systolic blood pressure to 90-100mmHg prior to cannulation to decrease the risk of dissection
  2. Venous Cannulation & Opening of the Venous Reservoir
    - Cannulation usually occurs in the right atrial appendage (RAE), and the patient is “on pump” once the venous reservoir is opened
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6
Q

Anesthetic Management for a Traditional On Pump Cardiac Surgery with an Arrested Heart

Anesthetist Tasks at the Onset of Bypass (1-5)

A
  1. Turn the ventilator and the vaporizer off
  2. Put vasoactive infusions in standby (but keep Amicar & insulin going)
  3. Measure pre-bypass urine output
    –This allows the anesthetist and perfusionist to know how much urine is produced on pump
  4. Chart BIS, MAP, and temperature while the patient is on pump
    –The target MAP should be in the 50-80mmHg range. Aortic dissection & cerebral hemorrhage are possible with high MAPs
  5. Put the monitor in “Bypass” mode (see next slide)
    –This turns off all the alarms
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7
Q

How do you change the monitor to bypass mode?

A
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8
Q

Anesthetic Management for a Traditional On Pump Cardiac Surgery with an Arrested Heart

Steps While On Bypass (11-15)

A
  1. Placement of the Cardioplegia Catheter
    - Antegrade cardioplegia is usually administered via the aortic root
  2. Aortic Cross Clamp Placement
    - Strain on the heart is minimized at this time because the heart is empty
  3. The Heart is Arrested with Cardioplegia
    - “Cardioplegia is typically given intermittently every 20 to 30 min, but may be given continuously”
  4. The CABG and/or Valve Repair is Performed by the Surgeon
    - Patient is usually cooled to some degree at this point
  5. Rewarming Phase
    - The risk for awareness increases during rewarming (due to the patient losing the anesthetic effects of the hypothermia)
    - Surgery is almost completed
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9
Q

What are possible drugs given during the rewarming phase?

A
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10
Q

Anesthetic Management for a Traditional On Pump Cardiac Surgery with an Arrested Heart

Steps to Coming Off Pump (16-24)

A
  1. The Perfusionist Refills The Heart With Blood By Partially Closing the Venous Reservoir
    - This will allow the surgeon to look for air bubbles prior to releasing the aortic cross clamp
  2. The Surgeon Looks for and Removes Any Air Bubbles
  3. The Aortic Cross Clamp is Removed
    - After aortic cross clamp removal, all the blood from the arterial cannula will rush into the heart and flush out all the cardioplegia, which will allow the heart to start beating again
  4. The Heart Comes Out of Asystole and Resumes Electrical Activity
    - Bradycardia/V-tach is expected
  5. Defibrillation (if Applicable)
    - If the heart goes into Vfib/Vtach, the surgeon will apply a 10-20J shock directly to the heart
  6. Reestablishment of an Effective Sinus Rhythm
    - Giving inotropic drugs (calcium, epi, milrinone, etc)
    - Having the surgeon place temporary pacing wires
  7. The anesthetist turns on the ventilator & Isoflurane
    - Now, because the heart is beating and the patient is oxygenating their own blood again, they will be ready to come off bypass
  8. The venous reservoir is completely closed
  9. The venous & aortic cannulas are removed
    - The patient is now “off-pump”
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11
Q

What are the pacing settings during surgery if needed?

A
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12
Q

Anesthetic Management for a Traditional On Pump Cardiac Surgery with an Arrested Heart

Steps After Bypass (25-29)

A
  1. Reversal of Heparin Anticoagulation
    - Protamine
    - Possible DDAVP (desmopressin)

26/27. Cell Saver Blood is Given (if Applicable)

26/27. Start a Sedation Drip for Transport

  • Propofol (20-50mcg/kg/min) Most common
  • Precedex
  1. The Chest is Closed and a Chest Drainage Tube is Placed
  2. Transport to the ICU with a Transport Monitor
    - Make sure to take a laryngoscope & vasoactive meds
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13
Q

Summary of pump steps (1-29)

A
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14
Q

What are concerns with a redo sternotomy?

A

“PRBCs (2 units) should be immediately available, and external defibrillation pads should be positioned before preparation and draping…If a complication does occur during sternotomy or exposure of the heart and cannulation sites, emergency bypass may be established by cannulating a femoral artery and vein.”

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15
Q

How do you manage a redo sternotomy?

A
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16
Q

What is normal blood loss after an open heart out of the chest tube?

A
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17
Q

What is reperfusion injury?

A
18
Q

What are causes of reperfusion injury?

A
19
Q

Why do you avoid using nitrous oxide during bypass surgery?

A
20
Q

What is an “off-pump” procedure, and when is it contraindicated?

A
21
Q

What can the Surgical Technique For A Off Pump CABG cause?

A
22
Q

Why is “off-pump” more difficult for the surgeon and the anesthetist?

A
23
Q

What are the advantages to “off-pump”?

A
24
Q

What are Disadvantages To Off Pump CABG Surgery?

A
  1. There is a much higher degree of hemodynamic instability throughout the procedure
    - Because the heart is often lifted, it is more challenging (and sometimes impossible) to prevent hypotension, arrhythmias, and decreased cardiac output, all of which can lead to myocardial ischemia
  2. The distal anastomosis may not be as good as those performed on pump
    - This may lead to increased platelet deposition at the anastomosis site, faster re-occlusion of the bypass graft (higher chance of graft thrombosis), and a higher chance of needing subsequent revascularization
  3. The total number of grafts being performed may be less on these patients, resulting in “under vascularization”
  4. There is a steep learning curve associated with performing off-pump bypass surgery, which can result in worse outcomes (such as the less complete revascularization)
25
Q

What are the most common procedures where “off-pump” might be indicated?

A
26
Q

During off pump CABG, what is the risk of proximal stenotic vessels?

A
27
Q

What is the main reason to read the preoperative Cath lab report?

A
28
Q

Which have better collateral circulation, stenotic or less stenotic vessels?

A
29
Q

How does the anesthetist prevent aortic disection during the proximal anastomose?

A
30
Q

What MAP should the anesthetist strive for during the distal anastomose?

A
31
Q

Off-pump CABG management

A
  1. The anesthetist should prepare to prevent hypotension, arrhythmias, and decreased cardiac output by doing the following:
    - 1a. Administering a fluid bolus after incision but prior to lifting the heart. Up to 2L crystalloid & 500mL colloid (If the fluid is administered too early, the patient is more likely to “pee it off” prior to the lifting of the heart)
    - 1b. Dosing antiarrhythmics prior to incision. Magnesium (1-2g) and Amiodarone (150mg)
    - 1c. Dosing calcium (1g) prior to lifting the heart for the distal anastomosis
    - 1d. Dosing vasopressors and/or inotropes while the heart is lifted
  2. The anesthetist doses Amicar, even though the CPB machine isn’t used
    - At Liberty, we use the same Amicar dose as the dose used in on pump cases (probably because all planned “off pump cases” can turn into “on pump cases”)
  3. Heparin is also administered, but the dose differs among institutions
    - Some use the same amount and require the same ACT as if the patient were going on pump; while others request a lower dose
  4. The anesthetist maintains blood pressure in the correct range, based on whether it is the proximals or distals being worked on
32
Q

What are Options When The Off Pump Technique Fails?

A
  1. Place the patient on full bypass and arrest the heart
  2. Place the patient on full or partial bypass and leave the heart beating
33
Q

Which is usually preferred? Full Bypass vs. Partial Bypass When The Heart Is Left Beating?

A
34
Q

Although the patient is exposed to bypass, pump assisted beating heart surgery has two benefits over the off pump technique. What are they?

A
35
Q

What are advantages to arresting the heart?

A
36
Q

What are disadvantages to arresting the heart?

A
37
Q

What are Advantages to Beating Heart Cardiac Surgery
(On or Off Pump)?

A
38
Q

What are Disadvantages to Beating Heart Cardiac Surgery
(On or Off Pump)?

A
39
Q

Which technique prevents myocardial damage more? “Pump Assisted Beating Heart” vs. “Arrested Heart” Surgery?

A
40
Q

Which technique has better success postoperatively? “Pump Assisted Beating Heart” vs. “Arrested Heart” Surgery?

A
41
Q

Which technique is better for patients with left ventricular dysfunction? “Pump Assisted Beating Heart” vs. “Arrested Heart” Surgery?

A

Methods of Anesthesia I (9 decks)

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