Vascular Thoracic Aneurysm & Carotids

Question 1

What is the anatomy associated with Thoracic Aneurysms?

Answer 1

-Located suprarenal, in thoracic cavity.
-If Aortic Arch is involved, lots of nerves and structures there (RLN, Vagus nerve)
-First branch off of Aorta is the Innominate -> Common Carotid and Subclavian

Question 2

What are S/Sx of a Thoracic Aneurysm?

Answer 2

-Asymptomatic
-hoarseness (RLN)
-stridor (RLN)
-dysphagia (RLN)
-dyspnea
-acute sharp pain in the chest, neck, between the shoulders
-Widened mediastinum on CXR

Question 3

How are thoracic aneurysms classified?

Answer 3

The type refers to the anatomy of the aorta involved, and the location of the problem.

Question 4

What is a Type 1 Type A Thoracic Aneurysm?

Answer 4

-70%
-Involves the Ascending Aorta
-Retrograde to the Aortic Valve
-Can cause acute Aortic Regurg due to being so close to the aortic root/valve area
-May require Aortic valve replacement or repair
-Coronary arteries may be involved and may require re-implantation
-Sternotomy, cardio-pulmonary bypass
-Can affect Innominate artery (1st branch off of aorta. Goes to axillary/radial. Can affect right radial pulse).

Question 5

What is a Type 2 Type A Thoracic Aneurysm?

Answer 5

-10%
-Extension is limited to the ascending aortic arch proximal to the left subclavian
-Innominate involvement always
-Sternotomy, cardio-pulmonary bypass

Question 6

What is a Type 3 (Type B) Thoracic Aneurysm?

Answer 6

-20%
-Descending aorta; begins distal to the left subclavian, but may extend to the iliac arteries
-Distal to great vessels but still in thoracic cavity
-Usually asymptomatic since it doesn’t involve great vessels or RLN
-May be able to be done as Left thoracotomy
-Requires ACC, may require partial bypass

Question 7

In general, describe the different locations of thoracic aneurysms.

Answer 7

-Aortic Root Aneurysm: involves aortic valve and can involve coronaries
-Ascending Aortic Aneurysm: Usually proximal to innominate. May or may not involve Aortic Valve
-Aortic Arch Aneurysm: involves great vessels (Carotids). May require hypothermic circ arrest. Very complicated
-Descending Aortic Aneurysm: beyond great vessels but still in thoracic cavity
-Thoracoabdominal Aneurysm: both the thoracic and abdominal aorta is involved. Bad

Question 8

What are the anesthetic goals for management of a Thoracic Aneurysm?

Answer 8

To preserve myocardial, renal, pulmonary, CNS, and visceral organ function.

Question 9

Describe hemodynamic management during a Thoracic Aneurysm repair?

Answer 9

-Control tachycardia, HTN, hypotension, anemia, hypothermia, shivering, give adequate analgesia
-B-blockade is more efficacious in preventing myocardial ischemia and infarction post-op than other anti-ischemic drugs
-If on bypass, has less hypotension in lower extremities compared to open AAA.

Question 10

When could you do a Thoracotomy for a thoracic aortic aneurysm?

Answer 10

If it’s in the Descending Thoracic Aorta.
-Would be in Right Lateral decubitus position
-Double Lumen Tube

Question 11

When do you do a Median Sternotomy for a Thoracic Aortic Aneurysm?

Answer 11

If it’s Ascending Aorta and Aortic Arch.
-Supine position.

Question 12

Describe management of One-Lung Ventilation in a Thoracic Aneurysm repair?

Answer 12

-Paralyzed patient, lateral decubitus position, open chest
-Left double lumen tube
-FiO2 = 100%
-Vt = 10-12cc/kg (maybe 7-10)
-PEEP 5-10cm to dependent lung
-CPAP to the non-ventilated lung is the single most effective maneuver to increase PaO2 during one lung ventilation
-Check ABG’s, watch SpO2
-Communicate with surgeon re: exposure, problems, needs
-Plan to change to a single lumen tube at the end of the case (go to ICU intubated)

Question 13

What is anesthetic management of a Thoracic Aortic Aneurysm?

Answer 13

-Art line always, probably femoral and upper extremity
-Swan (CCO/SvO2), Foley, Temp, 5 Lead ECG, TEE
-2 large bore IVs
-drips available: NTG, Neo, SNP, dopamine, primacor
-heart rate control: esmolol, labetalol, lopressor
-NG tube
-Type & Cross match, rapid infuser, warmer, and lots of blood products available in the room (huge suture lines on aorta and trauma to vasculature)
-FFP, platelets, Cryo

Question 14

Why do you need 2 Art lines during thoracic aortic aneurysm repair?

Answer 14

-Placement is important depending on the location of the aneurysm
-You must be able to monitor proximal and distal to the clamp.
-If you place right radial and aneurysm is involving aortic arch, that will get clamped off and won’t work during case.
-Femoral arterial line placement should be discussed with the surgical team…one groin may be needed for partial CPB

Question 15

Describe an Aortic Root Repair

Answer 15

-Ascending aortic aneurysm repair
-With or without AVR
-DHCA not needed
-Coronaries must be resewn into graft

Question 16

Describe an Aortic Arch Repair

Answer 16

-Requires DHCA and cardiac standstill
-Whenever you clamp off the great vessels, will stop blood flow to brain and upper extremities.
-Can do a bypass using the Axillary artery to the brain. Right radial A-line will monitor brain perfusion
-If you do this, have to have a Left radial or femoral Art Line to monitor body flow during case
-Coagulopathies common due to long time on pump and also have increased risk of bleeding due to suture lines. Need lots of products (Cryo, FFP, Plts, DDAVP)

Question 17

Describe a Hemi Arch Repair with DHCA.

Answer 17

-Involves Retrograde or Antegrade Cerebral Perfusion

Cerebral Protection required:
-Deep, systemic hypothermia (26 degrees)
-Topical cerebral cooling (ice packs)
-Cerebral hyperthermia prevention during rewarming (need nasal probe so brain doesn’t get too hot). Rewarming takes a long time.
-Burst suppression

Lots of suture lines: HTN post-op can be catastrophic: Aggressive BP management

Question 18

What is Retrograde Cerebral Perfusion?

Answer 18

Not as commonly done anymore, difficult.
-Allow flow through SVC to brain (limit Pressure to 25mmhg)

Question 19

What is Antegrade Cerebral Perfusion?

Answer 19

Cannulate axillary artery or innominate to provide “brain perfusion”
-Brain perfusion dependent on intact Circle of Willis. Only goes up Right Carotid, so if not intact COW, only perfuses half of the brain.
-Watch NIRS carefully

Question 20

How do you cause Burst Suppression?

Answer 20

-Monitor EEG for isoelectric or BIS of 0.
-Can administer large amounts of Propofol and Keppra

Question 21

What is Carotid Artery Disease?

Answer 21

-Most common cause: Atherosclerosis
-Patho: Embolism, occlusion, or hypoperfusion

Question 22

What are S/sx of Carotid Artery Disease?

Answer 22

-Amaurosis Fugax: Transient Monocular blindness
-TIA’s, paresthesias, speech problems, clumsiness of extremities, STROKE

Question 23

What is treatment of Carotid Artery Disease?

Answer 23

Medical treatment:
-Platelet inhibitors, Statins
-Mgmt of other risk factors (HTN, DM, Dyslipidemia, Tobacco use, CAD)

Surgical Treatment:
-Carotid Endarterectomy (CEA)
-Carotid Artery stent (CAS)

Question 24

What is Carotid Artery stenting (CAS)?

Answer 24

Less common now than CEA.
-Minimally invasive
-Good for sicker patients who can’t handle open
-Studies show increased risk of 30 day stoke/death compared with CEA in pts over 70

Question 25

What is Anesthetic Management for CEA/CAS?

Answer 25

-GETA or Regional (Cervical block to assess neuro status ASAP)
-Pre induction: routine monitors + Art line
-GETA: Etomidate vs Prop, Esmolol available. Smooth induction with minimal hemodynamic changes
-Keep BP within 20% of baseline even if hypertensive to reduce risk of stroke (Stable, “high normal” BP)
-Maintain normocarbia, normothermia, and avoid hyperglycemia,
-Patients will be heparinized

Question 26

Why would they monitor Stump Pressure during CEA?

Answer 26

Can do stump pressures to decide if they’re going to do a bypass while they’re doing a CEA
-Can check pressure distally and see what it is. If 45 or less, will do a bypass (Indicates cerebral hypoperfusion). Bypass location of CAE before doing surgery.
-Do this because patient will stroke if they’re clamped without bypass.
-Remember: perfusion is dependent on intact circle of willis if only bypassing one side

Question 27

How do you monitor for Ischemic changes/stroke during CEA?

Answer 27

-EEG
-Carotid stump pressure
-Somatosensory-evoked potentials (SSEPs),
-Transcranial Doppler
-Cerebral oximetry

Question 28

What is a Carotid Shunt?

Answer 28

Can be done instead of a bypass during CEA.
-Blood flow exits aorta, goes around where they’re working, and goes up to brain.

Question 29

Describe emergence of a patient from Carotid surgery?

Answer 29

Plan for a prompt emergence: Try to avoid coughing on the tube
Neuro exam as soon as the patient is extubated:
-MAE X 4
-Coherent speech
-Tongue is midline

Bringbacks can be an airway nightmare!
-Hematoma, tracheal swelling and deviation

Question 30

Describe Regional Anesthesia for Carotid Surgery.

Answer 30

-Local infiltration vs superficial and deep cervical plexus block
-Allows on-going assessment of the patients’ neurological status
-LOC is the most effective method of detecting cerebral ischemia
-Limiting factor: Patient acceptance

Question 31

What happens with Carotid sinus manipulation?

Answer 31

Can have bradycardia and hypotension due to baroreceptors in the carotid artery.
-Can use local infiltration at carotid to help with this.

Question 32

When is Cerebral Oximetry used?

Answer 32

-CEAs
-CPB cases in heart rooms

Question 33

What is Near-Infrared Spectroscopy?

Answer 33

-Regional tissue oxygenation
-Differential absorption of near-infrared light: Oxyhemoglobin vs Deoxyhemoglobin
-Regional tissue saturation baseline:70-75%

Question 34

What are the hemodynamics associated with AV grafts?

Answer 34

-Consider patient population: HTN, DM, renal failure
-Patients with A-V fistulas have increased venous return, decreased SVR
-Note widened pulse pressure, low diastolic pressure

Question 35

What is important to assess for patients with renal failure?

Answer 35

-Presence of anemia
-Coagulopathies secondary to decreased platelet adhesiveness
-Consider volume status, last dialysis
-Electrolyte disturbances: increased K+, increased Mg+, decreased Ca++