Module 7

Question 1

Module 7
Anesthesia for Vascular and Endovascular Surgery

Pathophysiology of Atherosclerosis
- Atherosclerosis is defined as the generalized inflammatory disorder of the arterial tree with associated endothelial dysfunction.
- Endothelial damage caused by hemodynamic _______(1).
- Inflammation from _______(2).
- _______(3).
- Hypercoagulability resulting in _______(4).
- Destruction of the fibrous cap over a lipid deposit leading to plaque rupture and _______(5).
- Vasoactive influences can result in spasms and acute _______(6).
- _______(7) play a pivotal role in atherothrombosis after plaque rupture.
- ______(a) derived macrophages act as scavenging and antigen presenting cells and also produce several types of chemical mediators (_______(8), chemokines).
- Adhesion molecules expressed by inflamed endothelium recruit leukocytes, including monocytes, which then penetrate into the intima, predisposing the vessel wall to lipid accretion and _______(9).

Study the Development of Atherosclerosis
Concept Map

Answer 1

Answers:

1. shear stress
2. chronic infections
3. Inflammatory response
4. thrombosis
5. ulceration
6. thrombosis
7. Platelets
   a. Monocyte
8. cytokines
9. vasculitis

Question 2

The Role of LDL
- Primary injurious agents include lipoproteins containing _______(1), the most important of which is LDL.
- These filter into arterial intima through the _______(2).
- Entrapped lipoproteins become modified into _______(3).
- In the subendothelial space enriched with atherogenic lipoproteins, most macrophages transform into foam cells
- Foam cells aggregate to form the _______(4).
- The atheromatous centers become necrotic, consisting of lipids, cholesterol crystals and cell debris.

Risk Factors
- The National Veterans Affairs Surgical Risk Study found the highest predictors of morbidity and mortality after vascular surgery include:
- Low serum _______(5)
- High ASA physical classification

• Additional Risk Factors:
  
  • Abdominal obesity
  • Dyslipidemia: Elevated LDL, Low HDL, Elevated _______(6) and small LDL particles
  • _______(7)
  • Insulin resistance
  • Proinflammatory state
  • Prothrombotic state
  • _______(8)
  • Family history of premature coronary heart disease
  • _______(9)

Please Study the Odds Ratio Image

Answer 2

Answers:
1. apolipoprotein B
2. endothelium
3. proinflammatory substances
4. atheromatous core
5. albumin
6. triglycerides
7. Hypertension
8. Smoking
9. Aging

Question 3

Occurrence
- More than 25 million persons in the US have at least one clinical manifestation of _______(1).
- Coronary artery atherosclerosis has been a major focus of investigation;
- However, atherosclerosis must be recognized as a systemic disease with important sequelae in many regional circulations (_______(2), aorta and extremities).
- How can we optimize the patient prior to _______(3)?

Comorbidity
- [A Venn diagram showing the percentage overlap of coronary artery disease, cerebral artery disease, and peripheral artery disease (PAD) is present but not described due to the limitations of the text-only format]

Answer 3

Answers:
1. atherosclerosis
2. brain
3. surgery

Question 4

Surgery or Cancellation?

(Please study the concept map)

• CAD: _______(1)
• ACS: _______(2)
• GDMT: _______(3) (HF trx)
• MACE: _______(4)
• MET: _______(5)
• NB: _______(6)
• CPG: _______(7) (ie: stent vs angioplasty)

Answer 4

Answers:
1. coronary artery disease
2. acute coronary syndrome
3. guideline directed medical therapy
4. major adverse cardiac event
5. metabolic equivalent
6. no benefit
7. clinical practice guideline

Question 5

Principle Clinical Syndromes
- Abdominal aortic aneurysms (_______(1))
- Aortic _______(2)

• Peripheral _______(3)
• Penetrating aortic _______(4)
• Intramural _______(5)
• Patients with peripheral arterial disease (PAD) can develop disabling symptoms of claudication or critical limb ischemia.
  
  • What is the test to differentiate reynaud vs claudication?
• Prevalence of claudication is 2% among older adults, but 10 times as many elderly patients have asymptomatic lower extremity _______(6).

Answer 5

Answers:
1. AAA
2. dissection
3. atheroembolism
4. ulcer
5. hematomas
6. atherosclerosis

Question 6

Principle Clinical Syndromes
- Abdominal aortic aneurysms (AAA)
- Aortic _______(1)

• Peripheral _______(2)
• Penetrating aortic ulcer
• Intramural hematomas
• Patients with peripheral arterial disease (PAD) can develop disabling symptoms of claudication or critical limb ischemia.
  
  • What is the test to differentiate reynaud vs _______(3)?
• Prevalence of claudication is 2% among older adults, but 10 times as many elderly patients have asymptomatic lower extremity _______(4).

Diagnostic Exams
- PAD affecting the lower extremities can be detected by the ankle-brachial index, the ratio of the highest systolic ankle pressure to the highest systolic arm blood pressure.
- The ankle-brachial index is the single best initial screening test to perform in a patient suspected of having PAD.
- The index is obtained with a blood pressure cuff and a hand held continuous wave doppler.
- It is calculated by dividing the systolic blood pressure at the ankle by the systolic blood pressure in the arm.
- A ratio < 0.9 is considered abnormal and a ratio of < 0.4 is often associated with limb threatening ischemia.
- Catheter based angiography is the standard method for diagnosing PAD, against which all other imaging modalities are compared for _______(5).
- Recent advances in noninvasive angiography (MRI & computed tomographic angiography) enable excellent noninvasive definition of the vascular anatomy.
- Carotid intima-media _______(6) is increasingly used as a surrogate marker for atherosclerosis.
- AAA occur in up to 5% of men older than 65 years most of which are small and require only infrequent follow-up.

Medical Therapy
- Continuation of chronic medical therapy may reduce perioperative morbidity and mortality in vascular surgery:
- Antihypertensives – beta blockers
- Statin drugs – reduce progression of plaque formation and reduce cardiovascular events in high risk patients; improve graft patency, limb salvage and decreased amputation rate
- _______(7)
- Hypoglycemics and/or insulin
- Other therapies:
- Meticulous foot care in diabetics to prevent infections
- Lifestyle changes – weight loss, exercise, _______(8)
- Chronic therapy with aspirin or other anti-inflammatory drugs may slow the progression of atherosclerosis and prevent myocardial vascular events.
- Patients should continue taking aspirin until the day of surgery for carotid _______(9).
- The decision should be individualized for patients scheduled for lower extremity vascular surgery.
- Several studies report that patients undergoing peripheral vascular surgery may benefit from statin therapy up to 48 hours before surgery showed no increase in major bleeding.
- What labs should be used to assess euglycics? AF-Xa Assay
- Urgent situations when patients develop acute ischemia, systemic anticoagulation may be initiated
- Discuss with the team whether heparin should be continued for patient with a high likelihood of clot.

Answer 6

Answers:
1. dissection
2. atheroembolism
3. claudication
4. atherosclerosis
5. accuracy
6. thickness
7. Aspirin
8. smoking
9. endarterectomy

Question 7

CAD + PVD
- The absence of severe coronary stenosis can be predicted with a positive predictive value of 96% for patients without diabetes, prior angina, previous MI or _______(1).
- Short term post op cardiac morbidity and mortality rates after vascular surgery are higher than after other types of non-cardiac _______(2).

• Complications after carotid endarterectomy (CEA) are less frequent than other vascular surgeries but still produce > 50% of the mortality encountered after vascular _______(3).
• Table 40-1 in Barash: In 1000 consecutive patients presenting for elective vascular surgery, a coronary angiography identified an overall prevalence of CAD of approximately 50% in this population. Severe correctable CAD was noted in 25% of the entire _______(4).

Please study Table 40-1

Answer 7

Answers:
1. CHF
2. surgery
3. surgery
4. series

Question 8

• The absence of severe CAD could be accurately predicted, with a predictive value of 96%, by the absence of clinical risk factors such as diabetes, prior angina, previous MI, and a history of congestive heart _______(1).
• Percutaneous coronary interventions (PCI) directed at reducing perioperative cardiac events do not appear to reduce perioperative MI (PMI).
• PCI performed in the distant past may be protective after vascular _______(2).
• Current guidelines recommend waiting at least 60 days following MI before elective noncardiac surgery in the absence of _______(3).
• Specific recommendations are made following PCI, and the ACC/AHA released a focused update on duration of dual antiplatelet therapy (DAPT) for patients with CAD in 2016; suggest delaying elective noncardiac surgery 30 days following _______(4) stent (BMS) placement and ideally 6 months following drug eluting stent (DES) placement.
• Two types of coronary stents: bare metal stents & drug eluting stents
• Drug eluting stents have reduced incidence of _______(5); they are also covered by endothelial cells.
  
  • However, the exposed stent material remains thrombogenic after the vascular trauma stent s needs to be on antiplatelet therapy.

Treatment algorithm for the timing of elective noncardiac surgery in patients with coronary stents.. BMS indicates bare metal stent; DAPT, dual antiplatelet therapy; DES, drug-eluting stent; and PCI, percutaneous coronary intervention.

Answer 8

Answers:
1. failure
2. surgery
3. intervention
4. bare metal
5. restenosis

Question 9

Types of Perioperative Myocardial Infarction (PMI)
- ______(a)-
- resembles that of acute nonsurgical MI probably due to acute coronary occlusion resulting from plaque rupture and _______(1).
- ______(b) -
- associated with sustained elevation of heart rate, absence of chest pain, and prolonged episodes of ST segment depression before overt MI
- associated with increased oxygen demand in the setting of fixed coronary stenosis; and, the O2 supply diminished by anemia or _______(2).

Perioperative Cardiovascular Risk
- Revised guidelines and classifications of clinical predictors of increased perioperative cardiovascular risk (MI, CHF and death)
- Guidelines place aortic and peripheral vascular surgery in the “______(c)” surgery category with an estimated cardiac risk (MI or cardiac related death) exceeding _______(3).
- Guidelines apply a stepwise approach to the evaluation of the patient incorporating clinical risk factors, exercise capacity and urgency of _______(4).

Risk Assessment
- Major predictors:
- active cardiac conditions to include acute MI (<7days)
- recent MI (7-30 days)
- unstable angina
- decompensated CHF
- severe valvular disease and significant arrhythmias
- cancellation of surgery is _______(5).

Answer 9

Answers:
a. Early
1. thrombosis
b. Delayed
2. hypotension
c. high risk
3. 5%
4. surgery
5. highly recommended

Question 10

Preoperative Coronary Revascularization:
- Should coronary revascularization be needed before vascular surgery, then surgical revascularization is a suitable option compared with percutaneous coronary interventions (PCI)
- The safe time interval between coronary revascularization and vascular surgery is:
- _______(1) for CABG
- _______(2) for bare metal stent (BMS)
- _______(3) for drug eluting stent (DES) (2-6 months)
- _______(4) for coronary angioplasty

Please study

Answer 10

Answers:
1. 4 to 6 weeks
2. 6 weeks
3. 1 year
4. 2 weeks

Question 11

Ischemia-Reperfusion Injury (IRI)

• Active process/biphasic process (ischemia and reperfusion)
• Both processes contribute to _______(1)
• The placement of a clamp directly injures perivascular endothelium and intima, including endothelial cells
• Injury and activation of endothelial cells triggers both immune/coagulation activation responses
• Ischemia/reperfusion injury (IRI) is a term used to describe functional and structural changes that become apparent during the restoration of the blood flow after a period of _______(2).
• In addition to the reversal of ischemia, the repair of blood flow can result in potentially very harmful effects such as necrosis of irreversibly damaged cells, marked cell swelling and nonuniform flow restoration to all portions of the _______(3).
• This chaotic restoration of the tissue flow, the _______(4) phenomenon, is the result of a vicious cycle of vascular, endothelial and mitochondrial dysfunction, with reduced local perfusion, intense dysfunctional changes, edema, and many more implications.
• The occurrence of metabolic disorders during ischemia or tissue hypoxia are currently well established, but clinical and experimental evidence shows that the significant events leading to cell and tissue dysfunctions are mostly related to the subsequent _______(5).

Please study the diagram of Ischemia and Reperfusion

Answer 11

Answers:
1. injury
2. ischemia
3. tissue
4. reflow
5. reperfusion

Question 12

Prevention of Myocardial Injury
- Pharmacologic prophylaxis against acute vascular events, in patients undergoing vascular surgery:
- Perioperative _______(1)
- Beta2 _______(2)
- _______(3) therapy
- Calcium channel _______(4)
- _______(5)

• Non-pharmacologic Approaches
  
  • Epidural anesthesia – reduce perioperative myocardial ischemia
  • Red blood cell transfusion – ______(a) is an independent predictor of adverse short and long term outcomes
  • Maintenance of ______(b) is cardio protective (shivering, tachycardia & hypertension should be avoided)
  • Endovascular Aortic Repair (EVAR) – studies may reveal fewer cardiac _______(6)

Answer 12

Answers:
1. beta-blockade
2. agonists
3. Statin
4. blockers
5. Nitroglycerin
a. anemia
b. normothermia
6. events

Question 13

Prevention of Kidney Injury

• _______(1) (AKI) is a common complication of vascular surgery and is associated with high morbidity & mortality
  
  • Incidence 16-22% with aortic surgeries
  • Mortality is 4-5 fold higher with kidney injury
  • Pathophysiology is multifactorial and includes ischemia/reperfusion injury (IRI); the use of nephrotoxic drugs (ACE inhibitors, NSAIDs, aminoglycosides, diuretics); _______(2) to renal arteries; and, _______(3) secondary to injury or immobilization.
• _______(4) is the most powerful predictor of postoperative renal dysfunction
• If patients receive chronic dialysis treatments, they should receive dialysis the day before or the same day as surgery
  
  • Some patients will actually be ______(5) as a result (hypotension on induction)
• ______(6) > Men: increased incidence of perioperative AKI

Acute Kidney Injury

• Intraoperative factors – hemodynamic instability, need for inotropic support and transfusion of > 5 units PC or autologous blood
  
  • Okay to use LR with kidney disease conversion of LR to lactate acid is old thinking
• The level of the ______(7) is correlated with AKI (suprarenal decreases renal blood flow by 80% versus infrarenal 45%) and reduced flow can persist for 30 minutes after release of the cross-clamp.

Answer 13

Answers:
1. Perioperative kidney injury
2. atheroembolization
3. rhabdomyolysis
4. Preoperative renal dysfunction
5. hypovolemic
6. Women
7. aortic clamping

Question 14

Pharmacologic Approaches to Renal Protection
- Unfortunately, despite multiple studies and bench research, there is a dearth of clinical evidence to support pharmacologic interventions and strategies. Regardless, mannitol, loop diuretics and dopamine are still used.
- ______(a) – induced osmotic diuresis, decreases epithelial and endothelial cell swelling, acts as a hydroxyl free-radical scavenger and increases synthesis of prostaglandin resulting in renal _______(1)
- ______(b) – used to maintain urine output not shown to improve renal _______(2)
- Dopamine – 0.5- 2mcg/kg/min renal blood flow, Na+ excretion, and glomerular filtration rate (_______3)

Non-Pharmacologic Approaches

• Goal is to minimize renal _______(4)
  
  • Cold renal artery perfusion to produce local _______(5)
    
    • Remote ischemic preconditioning is thought to prevent _______(6) in multiple organ systems by inducing ischemic protection pathways
• Intermittent cross clamping of the internal _______(7) reduces the incidence of renal insufficiency by 23%
  
  • However, repeated clamping of non-operative arteries in patients with severe atherosclerosis increases the risk of adverse _______(8)
• Endovascular aortic repair (EVAR) decreases kidney _______(9) because of elimination of aortic cross clamping
  
  • However, ______(c)-induced _______(10) is a significant cause of kidney dysfunction
• Preoperative prevention strategies are aimed at minimizing contrast _______(11)
  
  • MRI or ______(d)-based contrast studies have been proposed for patients at risk for contrast mediated _______(12)
  • Ensuring adequate _______(13) is important

Answer 14

Answers:

a. Mannitol
b. Loop Diuretics
1. vasodilation
2. outcome
3. GFR
4. ischemia
5. hypothermia
6. IRI
7. iliacs
8. events
9. IRI
c. contrast
10. neuropathy
11. exposure
d. gadolinium
12. nephropathy
13. hydration

Question 15

Preventing Pulmonary Complications

• Common in vascular surgeries with an incidence of 10-30% in AAA patients; patients with abdominal surgeries lasting > 3 hours; emergency surgeries; pre-op CHF; and, pre-op chronic lung disease
• The most effective preventive measure is postoperative lung expansion, either _______(1) or incentive _______(2)
• Anesthetic technique is an independent _______(3)
• Postoperative _______(4) analgesia reduces post op respiratory failure and duration of mechanical ventilation; there is some discussion of using lower _______(5)

Protect CNS/Spinal Cord
- Vascular surgery patients are at high risk for post-op central nervous system disease, including delirium, stroke, and _______(6) ischemia
- Age, preoperative cognition, depression, alcohol abuse, intraoperative blood transfusions are _______(7) factors
- CVA nearly twice as common in AAA _______(8)
- Open thoracoabdominal aortic aneurysm repair carries a higher risk of _______(9) than AAA repair.
- TEVAR is _______(10)
- Patients with symptomatic carotid stenosis benefit from _______(11) prior to major vascular surgery
- What about patients with _______(12) and discontinuation of antiplatelet therapy?

Answer 15

Answers:

1. CPAP
2. spirometry
3. factor
4. thoracic epidural
5. VT
6. spinal cord
7. risk
8. repairs
9. stroke
10. lower
11. CEA
12. Afib

Question 16

Protecting the Spinal Cord

• Spinal cord ischemia occurs up to 11% in operations involving a distal aortic _______(1)
• Spinal cord is supplied by two posterior arteries, together they supply ______(a)% of spinal cord blood _______(2)
• The anterior spinal _______(3)
  
  • supplies ______(b)% of spinal cord blood flow and is the primary supply to the _______(4) cord
  • The anterior spinal artery is fed by a series of radicular arteries arising from the _______(5), and collateralization is _______(6)
  • The blood supply to the thoracolumbar cord is derived from the _______(7).
    
    • EXAM QUESTION: In 75% of cases, it joins the anterior spinal artery between _______(8) and _______, and in 10% of cases it joins between _______(9) and _______(10)

Answer 16

Answers:
1. repair
a. 25
2. flow
3. artery
b. 75
4. anterolateral
5. aorta
6. poor
7. radicular artery of Adamkiewicz
8. T8
9. T12
10. L1 and L2

Question 17

Protecting the Spinal Cord

• Much of the flow in the anterior spinal artery depends on the artery of _______(1)
• Flow in the spinal arteries is often bidirectional and the blood supply to the spinal cord can be shunted to the rest of the body when perfusion pressures are _______(2)
• Standard measures to prevent spinal cord _______(3)
  
  • a short cross clamp _______(4)
  • maintenance of normal cardiac _______(5)
• high perfusion _______(6)
• Surgeons may place a “______(a)” (a heparinized tube that can decompress the heart and also provide distal _______(7)); however, even with a Gott shunt or partial bypass, there may be a period of visceral _______(8)
• Other surgeons may place a temporary ex vivo right axillofemoral bypass graft before positioning for _______(9).
  
  • After the thoracic surgery, graft is removed, placement of shunt attenuates the hemodynamic response to aortic cross clamping, acidosis, hormonal and metabolic changes with aortic _______(10)
• Partial bypass is another option either from left atrium or ascending aorta to the iliac or femoral artery to provide distal _______(11)
• A heat exchanger is used to induce hypothermia adds to _______(12)
• Segmental sequential surgical repair duration of _______(13)
• Intercostal artery reattachment in hopes of preserving blood flow to the anterior spinal artery may be _______(14)
• Atrial-femoral artery shunt with partial bypass lends for better
  
  • operative field _______(15)
  • Reduces _______(16)
  • Maintains stable distal aortic _______(17)
  • Reduces (but not eliminates) head and neck _______(18)

A markedly decreased incidence of neurologic deficits were reported with distal aortic perfusion combined with drainage of CSF
CSF drainage improves the pressure gradient → allowing spinal cord blood flow as aortic occlusion lowers distal arterial pressures and increases the CVP
CSF drainage is employed in both endovascular/open techniques

Answer 17

Answers:
1. Adamkiewicz
2. low
3. ischemia
4. time
5. function
6. pressures
a. Gott shunt
7. perfusion
8. ischemia
9. thoracotomy
10. occlusion
11. perfusion
12. neuroprotection
13. ischemia
14. beneficial
15. exposure
16. afterload
17. perfusion
18. edema

Question 18

Carotid Stenosis

• Carotid disease is usually a problem with embolization and less often occlusion or insufficiency
• Most common non-invasive test is _______(1).
  
  • Estimated sensitivity and specificity of this test to detect a carotid artery stenosis greater than _______(2) are approximately 94% and 92%, respectively, when using digital subtraction angiography as the reference standard.
    
    • Positive tests are usually followed by confirmatory angiography
• Optimal treatment of asymptomatic carotid stenosis is controversial
• Recommendations for medical therapy include: smoking cessation, aspirin therapy, blood pressure control and statin therapy
• CEA over medical therapy for asymptomatic stenosis only when both the perioperative risk is low, and the patient is expected to live more than _______(3) years
• Symptomatic carotid stenosis – CEA with _______(4) therapy
• Carotid stenting versus open _______(5)
• Carotid Stenosis: high risk of _______(6) or CVA
  
  • CEA reduces stroke risk when carotid stenosis > _______(7)
• _______(8) (temporary one eye blindness) = sign of impending stroke; 25% of pt with high-grade stenosis
• Awake pt is the best method to assess neurologic integrity
• During cross-clamping, maintain a normal to slightly elevated _______(9)
• After the cross-clamp removed, keep SBP under _______(10) mmHg (\ bleeding)

Answer 18

Answers:
1. carotid duplex ultrasound
2. 60%
3. 10
4. aspirin
5. CEA
6. TIA
7. 70%
8. Amaurosis fugax
9. BP
10. 145

Question 19

Carotid Endarterectomy (CEA)

Indications:
- History of _______(1)
- Symptomatic patients with stenosis of more than _______(2) occlusion
- Patients who have suffered a stroke are NOT candidates for CEA in the acute phases of recovery.
- Consideration to chronic issues related to the stroke must be evaluated.

Pre-Op for CEA
- Continue ______(3) until the day of surgery
- Antiplatelet therapy – stop ______(4) days before surgery (generally)
- Not advisable to delay urgent surgery that might prevent a stroke for extensive cardiac evaluation even in patients with known CAD

Answer 19

Answers:
1. TIA
2. 70%
3. aspirin
4. 5

Question 20

Carotid Endarterectomy (CEA)

• What is the leading cause of perioperative mortality after CEA?
  
  • _______(1)
• Remember:
  
  • Myocardial Infarction
  • Normal cerebral blood flow:
    
    • _______(2) ml/100 g/min (15% of cardiac output)
  • Normal CMRO2:
    
    • _______(3) ml/100 g/min (20% of O2 consumption)
  • Cerebral blood flow at which ischemia is apparent on EEG (critical regional CBF)
    
    • _______(4) ml/100g/min
• Regional Cerebral Blood Flow (rCBF)
  
  • Utilizes PET scanning and MRI
  • Can be calculated by measuring the washout of radioisotopes from the distribution of the middle cerebral artery.
  • These studies allow the determination of the critical regional cerebral blood flow, the flow rate below which _______(5) of patients show EEG signs of ischemia.
• Brain receives ~_______(6)% of Cardiac Output (CO)
• CBF average is _______(7) ml/100 g/min
  
  • Gray matter is _______(8) ml/100 g/min
  • White matter is _______(9) ml/100 g/min
• Flow rates below _______(10) ml/100g/min are associated with impairment
• Flow rates between _______(11) ml/100g/min show a flattened EEG.
• Flow rates below _______(12) ml/100g/min are associated with irreversible brain damage.
• What intravenous solution should NOT be given to a patient undergoing CEA?

Isolyte
Lactated Ringer’s
______(13)
Normal Saline
Avoid ______(13)
Moderate hyperglycemia worsens ischemic brain injury.
Elevated blood glucose levels contribute to the development of severe lactic acidosis during brain ischemia in carotid occlusion resulting in unfavorable neurological outcomes.

Answer 20

Answers:
1. Myocardial Infarction
2. 40-60
3. 3-4
4. 18-20
5. 50%
6. 15
7. 50
8. 80
9. 20
10. 20 - 25
11. 15-20
12. 10
13. D5W

Question 21

Carotid Endarterectomy

• Regional anesthesia
  
  • Local infiltration or Superficial/deep cervical plexus block (_______(1))
  • Risk of ipsilateral _______(2) nerve block → dyspnea due to paralysis of the hemidiaphragm
• General anesthesia
  
  • Does not require pt cooperation
  • _______(3) airway
  • Ability to administer agents that reduce cerebral metabolic rate
  • May require monitors of _______(4)
• Monitors of adequate cerebral perfusion
  
  • _______(5): high incidence of false-negatives
  • Cerebral Oximetry: cerebral perfusion at risk when rSO2 ≥ _______(6)% baseline
  • Transcranial doppler: assessment of continuous blood flow velocity _______(7)
  • SSEP: _______(8) pathways only
  • Carotid stump pressures: pressures distal to the clamp
    
    • Special pops: how much stump pressure is your goal? _______(9) mmHg

Answer 21

Answers:
1. C2-4
2. phrenic
3. Controlled
4. CBF
5. EEG
6. 25
7. MCA
8. sensory
9. 50

Question 22

Intra-Op Goals for CEA

• Hyperglycemia (glucose >_______(1) mg/dL) has a documented association with worse outcome after CEA
• All anesthetic agents reduce cerebral metabolism O2 demand of the brain
• Volatile agents provide “preconditioning” by inducing _______(2)
• ______(a) offer a degree of brain protection during periods of regional ischemia
  
  • Thiopental cerebral metabolic O2 requirements to _______(3)% of baseline = silent EEG
• Etomidate and Propofol brain electrical activity and cellular O2 requirements
  
  • Etomidate – preserves _______(4) stability
  • Propofol – allows for rapid awakening with quick neuro assessment
    
    • Comes off pretty fast, we can keep them deep and still _______(5)
• Cerebral autoregulation is impaired by ______(b) but preserved under propofol-remifentanil anesthesia
• Hypothermia can depress neuronal activity
• Temporary occlusion (cross clamp) of the carotid artery acutely disrupts _______(6)
  
  • Important to know adequacy of blood flow in _______(7) carotid
• Continued blood supply to the brain depends on collateral blood flow through the Circle of Willis if a shunt is used
  
  • Patients with bilateral carotid disease > risk of _______(8)
• Keep arterial blood pressure higher during cross-clamp to augment cerebral blood flow
  
  • Blood vessels in ischemic areas of the brain have lost autoregulation
• Stroke is generally due to embolic events not necessarily hypotension or hypertension
  
  • Surgeons will utilize a shunt to provide blood flow during cross clamp
  • IVF, vasoconstrictors (phenylephrine) to maintain BP _______(9)% above baseline
  • Perioperative MI may occur in these patients
• Avoid hypercapnia/hypocapnia during _______(10)

Answer 22

Answers:
1. 200
2. nitric oxide synthase
a. Barbiturates
3. 50
4. cardiovascular
5. wake up rapidly
b. sevoflurane
6. BF (blood flow)
7. OTHER
8. CVA
9. 20
10. GA (general anesthesia)

Question 23

Carotid Endarterectomy (CEA)

• What about PaCO2?
  
  • Inconclusive; current literature reviews describe no benefit from manipulating mechanical ventilation to vasodilate or vasoconstrict cerebral vessels during CEA.
• Therefore, it is currently recommended that PaCO2 should be maintained at near _______(1) values.
• What corrective measures should the nurse anesthetist implement if intraoperative bradycardia & hypotension occurs?
  
  • Surgical manipulation of the _______(2) cause symptomatic bradycardia & hypotension.
  • Request the surgeon locally _______(3) the carotid bifurcation with 1% Lidocaine to control the symptoms.
  • Treat hypotension with _______(4).
• Baroreceptor reflex bradycardia, hypotension; anticholinergic
• Head position → compression of carotid +/or vertebral arteries
• Maintain normocapnia or mild hypocapnia → prevent “steal” phenomenon by shunting blood away from hypoperfused tissue
• Glucose > _______(5) mg/dL DOS → may increase risk of stroke or death
• Post-op complications: hematoma (think _______(6) if unable to grab surgeon!), RLN injury, labile BP (exposed baroreceptor), stroke (embolic, not perfusion); reduced ventilatory response to hypoxia (carotid body denervation)

Techniques for Brain Monitoring

• Carotid Stump Pressures
  
  • Used to predict collateral flow distal to the occluded carotid artery.
  • Defined as “the pressure in the ______(a) stump of the occluded artery.”
  • Pressure and flow do not necessarily correlate.
  • Stump pressures of _______(7) mmHg or above may not adequately ensure adequate regional perfusion.

Answer 23

Answers:
1. normal
2. carotid sinus & baroreceptors
3. infiltrate
4. phenylephrine
5. 200
6. thickened airway
a. distal
7. 40-50

Question 24

Shunts

• Practice variations among surgeons _______(1) vs. asleep
• Placement of shunt associated with embolic related stroke rate of ~ _______(2)%
• Technical problems with shunts include: air embolism, kinking of the shunt, shunt occlusion, injury or disruption of the distal internal carotid artery which may impair surgical access to the artery and increase cross clamp time
• Monitoring for embolic events: _______(3) patient or use of a transcranial doppler, SSEP, EEG, or cerebral oximetry

Techniques for Brain Monitoring

• Changes in ______(a), signals are sensitive parameters for ischemia, because electrophysiologic activity accounts for about _______(4)% of normal cerebral energy expenditure.
• However, these changes in electrical activity are not necessarily specific for ischemia that is severe enough to threaten cellular integrity.
• EEGs/SSEPs
  
  • They are also affected by changes in physiologic parameters to include temperature, PaCO2, and the depth of anesthesia.
• EEG/SSEPs reflect specific parts of the brain.
  
  • EEG – _______(5)
  • SSEPs – specific sensory central nervous pathways (i.e., _______(6) )

Answer 24

Answers:
1. awake
2. 1
3. awake
a. EEG or Somatosensory Evoked Potentials (SSEPs)
4. 60
5. cerebral cortex
6. dorsal columns and lateral funiculus

Question 25

Carotid Endarterectomy (CEA)

• Regional Anesthesia includes a deep & superficial cervical plexus block (C2 - C4)
  
  • Advantages:
    
    • patient is _______(1) & follows commands
    • able to evaluate neurologic status during _______(2)
    • greater hemodynamic stability
  • Disadvantages:
    
    • Length of case
    • Ability of surgeon and instrumentation
    • Ability of the patient to cooperate
• Postoperatively, aim for normotensive to slightly hypotensive blood pressure relative to patient’s _______(3) BP to decrease risk of bleeding & tension on the suture line.
• Acute hypertension occurs as a result of surgical dissection or denervation of the carotid sinus with resultant decreases in baroreceptor _______(4) some sedation during cross clamp
• Goal is to as:
• Postoperative ______(5) - identified as a major risk factor for neurologic deficit and myocardial ischemia, related to impaired carotid baroreceptor function.
• Post-operative respiratory depression after CEA may be caused by:
  
  • _______(6) RLN injury
  • _______(7)
  • Deficient carotid body function, particularly following bilateral CEAs
    
    • which abolishes cardiorespiratory responses to hypoxemia and rendering respiratory regulation totally dependent on changes in PaCO2.

Awake CEA

• Arterial line placement (20% higher during cross clamp)
• Very little sedation/heparin and protamine available
• Cervical plexus block (deep and superficial)
• Neuro checks in the operating room (contralateral side)
• Beach chair position/may or may not need neck roll
• Arms tucked with hand available to do hand grips
• “Verbal” anesthesia
• Carebral oximetry
• Can vagal (surgeon can inject lidocaine in sheath)
• Alterations in baroreceptors can occur
• Avoid _______(8) for cerebral ischemia during clamp

Answer 25

Answers:
1. awake
2. cross-clamping
3. pre-operative
4. activity
5. hypertension
6. Bilateral
7. Massive hematoma
8. excesses

Question 26

GA for CEA

• Arterial line keep B/P ______(a) % higher during cross clamp
• Need vasopressors available (nitro and phenylephrine)
• Cerebral oximetry/EEG/SSEP
• Beach chair /neck roll / arms tucked
• Use drugs allow for “quick wake up” (______(b), avoid versed, precedex gtt)
• Surgeons generally shunt
• Extubate without a lot of bucking or coughing
• May need to titrate ______(c) for wake up as BP increases
• Neuro checks immediately post-op
• Heparin and protamine available
• T & S if H/H is low, EBL is generally <_______(1)cc
• TEE optional in high risk patients

Regional for CEA

• Greater stability of blood pressure
• Easy cerebral monitoring
• Avoidance of tracheal intubation
• Fewer episodes of EEG ischemia compared with GA
• Need to shunt not necessary unless they show confusion during cross clamp
• Hospital costs are lower with RA with _______(2) hr discharge
• Disadvantages: requires a _______(3)
  
  • Surgeon must have specific skill set and instrumentation
  • No brain protection with anesthetics

Common Problems after CEA

• Onset of neurologic dysfunction and hemodynamic instability
• Respiratory insufficiency? Recurrent laryngeal nerve?
• Temporary cranial nerve injuries- vagus/hypoglossal
• Temporary marginal mandibular nerve deficits
• Mild cervical numbness
• Hematomas; Wound infections
• Hyperperfusion syndrome – HTN/headache (treat with steroids)
• Blood pressure abnormalities (Hydralazine is useful, if bradycardia is present)

Answer 26

Answers:
a. 20
b. remifentanil gtt/desflurane
c. nitro
1. 100
2. 24
3. cooperative patient

Question 27

Carotid Stenosis

• Carotid Artery Angioplasty Stenting (CAS)
  
  • Maintain ACT > _______(1) seconds
  • Balloon inflation can activate the ______(a) reflex, leading to bradycardia and hypotension.
    
    • Pretreat with atropine or glycopyrrolate to attenuate response
  • Most common complication is ______(b) due to atherosclerotic debris that lodges in the cerebral _______(2).
  • Trx: recombinant tissue _______(3)
• Subclavian Steal Syndrome
  
  • Occlusion of the subclavian or innominate artery proximal to the origin of the ipsilateral vertebral artery (usually left side)
  • Reversal of blood flow; “stolen” from the ______(c) cerebral circ
  • Blood pressure is much lower in ipsilateral arm
    
    • Take BP in both arms
  • S & S: syncope, vertigo, ataxia, hemiplegia, ischemia to the ipsilateral arm
  • Trx: subclavian endarterectomy

Answer 27

Answers:
1. 250
a. baroreceptor
b. thromboembolic stroke
2. vasculature
3. plasminogen activator
c. posterior

Question 28

Carotid Angioplasty and Stenting

• Performed in vascular interventional suite by team of vascular surgeons, cardiologists, or radiologists
• Frequently anesthesia is not involved although in complex cases, we may be asked to provide sedation
• Patients need to be responsive
• Adequate heparinization is crucial ACT > _______(1)
  
  • Concern for cerebral embolization
    
    • Aspirin and clopidogrel (Plavix) therapy for _______(2) days

Management of Emergencies

• Patients who awaken with a major new neurologic deficit or who develop a suspected stroke immediately _______(3):
• Neuro deficits occasionally are due to inadequate collateral flow
• New deficits warrant re-exploration
• Cerebral protection is considered
• Focal or minor deficits due to microembolization
• Full stomach?
• Wound hematomas - trach/cricothyroid tray available due to potentially difficult airway

Please study the Aortic Reconstruction
Diagram

Answer 28

Answers:
1. 300
2. 30
3. post-op

Question 29

Aortic Reconstruction

• Aneurysms – mortality from rupture is ~_______(1)%. Early recognition and treatment is key.
• Most centers can offer an endovascular approach for infrarenal repairs; while juxtarenal, suprarenal and thoracoabdominal are routinely done open though some centers are changing
• Occlusive disease – some patients present with stenosis; aorta-bifemoral bypass

Risk Factors

• Advanced age
• Smoking > _______(2) years
• Hypertension
• Low serum high density lipoprotein cholesterol
• High level of plasma fibrinogen
• Low blood platelet count
• AAA screening should be done in men aged _______(3) to 75 years of age who smoke.

Answer 29

Answers:
1. 85
2. 40
3. 65

Question 30

Aneurysms

• First successful repair by Dr. Michael DeBakey in 1955.
• Most frequent cause of aortic aneurysms is atherosclerosis.
• Anesthetic management is complicated by aortic cross-clamping that results in increased left ventricular _______(1) & severely compromised organ perfusion distal to the point of occlusion
• Large amount of intraoperative blood loss
• Crawford type ______(a) aneurysms present the most significant perioperative risk, including _______(2) or renal failure following surgery.
• Acute dissection of the ascending aorta is a ______(b) emergency.
  
  • The aortic valve is often affected, so consider aortic _______(3) in your anesthetic plan.
  • Full, Fast, Forward!
• Stanford (Daily) type A: ______(c) dissections involving the ______(d) aorta (nearly always necessitate surgical treatment)
• Stanford (Daily) type B: ______(e) dissections involving ______(f) aorta (distal of the left subclavian artery) – maybe treated medically with aggressive control of blood pressure

Please study the classification of Aortic Dissection diagram

Answer 30

Answers:
1. pre-load
a. 2
2. paraplegia
b. surgical
3. insufficiency
c. Proximal
d. ascending
e. Distal
f. descending

Question 31

Aneurysms

• AAA is generally symptomless. It’s most commonly detected as a pulsatile abdominal mass during routine examination.
  
  • CT, US, MRI
• The mechanisms for the development of AAA are the destruction of elastin and collagen (primary), inflammation, endothelial dysfunction, platelet activation, and atherosclerosis.
• Law of ______(a): vessel radius x transmural pressure = wall stress, ↑ radius ↑ transmural P ↑ wall stress
• Surgical correction is recommended when the aneurysm exceeds _______(1) cm or if it grows more than _______(2) per year
• The classic triad of AAA rupture consists of ______(b).
  
  • This triad is only present in about _______(3)% of patients
• Application of the aortic cross clamp creates central hypervolemia by
  
  • increasing ______(c) and reducing _______(4)
  • shifting a greater proportion of the blood volume _______(5) to the clamp
  • ______(d) MAP, SVR, and CvO2
• Removal of aortic cross clamp creates central hypovolemia by
  
  • restoring venous _______(6) and decreasing venous return
  • shifting blood to the ______(e) body
  • ______(f) CO, MAP, SVR, and SvO2
  • Creating a _______(7) — loss of intravascular tone
  • “______(g)” is defined as a 4-to-7 fold increase in blood flow to tissues deprived of flow during clamping

Answer 31

Answers:

a. Laplace
1. 5.5
2. 0.6 - 0.8
b. hypotension, back pain, and a pulsatile abdominal mass
3. 50
c. venous return
4. venous capacity
5. proximal
d. increases
6. capacity
e. lower
f. Decreases
7. capillary leak
g. Reactive hyperemia

Question 32

Aneurysms

Cross-clamp → anaerobic metabolism
- ______(a) in lactic acid production metabolic acidosis, prostaglandins, activated complement, & myocardial _______(1) factors
- ______(b) in temperature

Compared to open aortic procedures, EVAR has several benefits including shorter operative times, lower rate of transfusion, shorter length of stay, and reduced morbidity
- Regional/local anesthetic
- No need for AoX & avoids respiratory risks re: large midline abd inc.
- IV dye allergic reaction, renal injury
- Complications: activation of baroreceptor reflex, massive hemorrhage, aortic rupture, cerebral embolism
- ________(c) : original graft fails to prevent blood from entering the aortic sac; spontaneous resolution or 2nd graft/open repair
-______(d) spinal arteries → perfuse the posterior 1/3 of the SC
- ______(e) spinal artery → perfuses the anterior 2/3 of the SC
- Artery of Adamkiewicz: most important radicular artery
- Perfuses ______(f) in the thoracolumbar region
- It most commonly originates on the left side between _______(2)

______(g)% of pop = T8-12
______(h)% of pop = L1-2
Cross-clamp above can cause ischemia to lower portion of the anterior SC

• Beck’s Syndrome
  
  • Flaccid paralysis of the lower extremities = ______(i)
  • Bowel and bladder dysfunction = ______(j) fibers
  • Loss of temperature & pain sensation = ______(k) tract
  • Touch and proprioception are preserved = ______(l) column

Answer 32

Answers:
a. Increases
1. depressant
b. Decrease
c. Endoleak
d. 2 posterior
e. 1 anterior
f. anterior SC
2. T11-T12
g. 75
h. 10
i. corticospinal tract
j. autonomic motor
k. spinothalamic
l. dorsal

Question 33

Endo v. Open v. Medical

• Open aortic repair (OAR) along with medical management used to be the only option.
• Stent insertions began ~1991 for infrarenal aortic aneurysms
• Decision for which modality of treatment depends upon:
  
  • AAA size
  • AAA morphology
  • Patient perioperative risk

Abdominal Aortic Aneurysms (AAA)

• Dilatation of the abdominal aorta generally below the renal arteries
  
  • Risk of rupture is directly related to the luminal diameter of the aneurysm
  • Aneurysm can develop an inner lining of mural thrombus
    
    • Risk of rupture >_______(1) to 5 cm
• Size is the most important predictor of subsequent rupture and mortality.
  
  • Risk of rupture is low < _______(2) in diameter
  • Risk rises exponentially >_______(3)
  • AAA between 4 and 5 cm diameter should be followed every 6 to 12 months to determine if increasing in size
  • Interesting finding of baseline hemoglobin concentration in AAA risk stratification is independently associated with AAA size and reduced long term survival following intervention for treatment (anemia present?)
  • In long-term follow-up, survival was significantly lower in patients with anemia as compared to patients without anemia (Hmmm…)

Answer 33

Answers:
1. 4.5
2. 4 cm
3. 5 cm

Question 34

Research re: EVAR

• 30 day mortality to be significantly lower with EVAR than OAR
• EVAR significant reduction in procedure time
• EVAR exposed to fluoroscopy
• Aneurysm related death lower in the EVAR group
• 6 year survival rates were the same, but EVAR had higher rates of secondary interventions
• EVAR did not reduce hospital costs
• Myocardial injury less with EVAR

EVAR

• Regional/local anesthesia or GA
• Arterial line, large bore peripheral IVs (x2) or central line (+/-)
• Before device insertion, systemic anticoagulation with heparin dose ______(a) units with goal ACT >_______(1) secs
• At the time of deployment, awake patients will be asked to hold their breath and mean arterial B/P is often lowered to decrease the risk of distal migration of the stent
• After stent deployment, anticoagulation is _______(2)
  
  • EBL minimal

Conversion from EVAR to OAR

• Incidence of conversion is less than 1%
• Setting of difficult arterial access site, poor anatomic parameters for EVAR such as tortuous iliac arteries
• Stent malposition, stent migration and aneurysm rupture
• Need for cell saver or general anesthesia
• Resuscitative equipment –fluid warmers, blood tubing
• Primary conversion is classified as an open reoperation within 30 days following EVAR and is most commonly associated with type I “_______(3)”
• Secondary conversion is aneurysm rupture despite successful sac exclusion

Answer 34

Answers:
a, 3,000-5,000
1. 200
2. reversed
3. endoleak

Question 35

Complications of EVAR
- ______(a) – most common complication (30%) defined as persistent blood flow outside the wall of the _______(1) graft into the _______(2) sac
- Exposes the weak _______(3) wall to continued flow that may lead to rupture
- Classifications of Endoleaks: Type I - IV

Endoleaks
- Type I – high flow leak adjacent to a _______(4) that is not sealing the sac from the _______(5) circulation (requires _______(6) intervention)
- Type II – low flow leak due to _______(7) branches that have been excluded by the stent (can be treated with _______(8))
- Type III- failure with the stent itself or at its junction with another stent (requires _______(9) recognition and _______(10))
- Type IV- porosity in the stent (often resolves with reversal of _______(11))
- Type V – (endotension) persistent or recurrent _______(12) of the aneurysm sac despite no detectable _______(13)

Types ______(b) are high pressure leaks and generally require urgent management due to high risk of sac _______(14).

Please study the types of Endoleaks

Answer 35

Answers:
a. Endoleaks
1. stent
2. aneurysm
3. aneurysm
4. stent
5. systemic
6. immediate
7. arterial
8. embolization
9. immediate
10. treatment
11. anticoagulation
12. pressurization
13. endoleak
b. I and III
14. rupture

Question 36

Open Aortic Repair
- Arterial line and large bore IV x2; consider CVP/PA for CAD
- NGT (consider using Afrin to reduce bleeding!)
- TEE may be indicated
- Ischemia of the anterior spinal cord is a concern
- Decrease CSF pressures by way of spinal catheter/drain and withdrawal of CSF fluid; be sure to _______(1) it.
- Placed at _______(2) interspace
- Drain 10 ml per hour slowly over an hour for several hours
- Thoracic epidural for pain control – be sure to manage it to allow for _______(3) on lower extremities.
- Surgical approach is through either a transperitoneal or a retroperitoneal approach
- Intraoperative blood loss can be significant T & C 4 units
- Cell saver
- May need _______(4) ventilation if lots of fluid shifts
- Fluid warmers and _______(5) circuits
- Keep the room warm
- _______(6) clamping carries lower risk
- _______(7) clamping carries the highest risk
- Aortic cross clamping increases mean arterial pressure and systemic vascular resistance by ______(a)%
- Preload changes are more _______(8) than blood pressure changes
- Patients with CAD, myocardial dysfunction may occur with cross clamping and increased filling pressures
- Need for nitroglycerin gt to attenuate the increased filling pressures
- Keep fluids at a _______(9) before cross clamp
- During cross clamp, volume load to keep CVP or PAD about ______(b) mmHg higher than baseline

• Reperfusion after unclamping the aorta causes systemic release of an acute load of _______(10).
• Severe arterial hypotension unless aggressive therapy is untaken.
  
  • Calcium Chloride, bicarbonate, vasopressors, fluid loading during cross clamp helps prevent hypotension
  • Gradual unclamping by surgeon helps and gradual sequential release of bilateral femoral pressure or rotating flow to one leg at a time in _______(11) grafts

Answer 36

Answers:
1. transduce
2. L3-4 or L4-5
3. neuro exams
4. postoperative
5. humidified
6. Infrarenal aortic
7. Suprarenal aortic
a. 50
8. variable
9. minimum
b. 3
10. potassium, acid and other mediators
11. aorto-bi-femoral

Question 37

Tips for Open Aortic Repair
- Anticipate the sudden changes in intravascular volume and SVR seen with clamping, unclamping and bleeding
- Prehydration may limit variations in BP
- Keep vital signs within _______(1) baseline
- Keep HR below 90
- Bolus with narcotics to keep HR and BP within range
- Maintain temperature (unless hypothermia for spinal cord protection)
- ______(a) for immediately before cross clamp or deepen agent
- Ensure adequate blood volume at the time of cross clamp removal
- ______(b) for perioperative HR control

Thoracic and Thoracoabdominal Aneurysm Repair
- Most challenging cases to manage
- Many patients have CAD and COPD
- Lung isolation is required for surgical exposure
- Lots of fluid shifts and edema in airway post procedure and may have to switch to single lumen tube or use bronchial blocker/univent tube. Extubate _______(2)!
- Partial bypass
- Perioperative morbidity is _______(3)
- TEVAR is advocated (decreases paraplegia)
- Intrathecal catheter placement
- CVP line/arterial line

Aortomesenteric Revascularization
- Chronic mesenteric ischemia is caused by _______(4)
- Acute mesenteric ischemia is usually ______(c) event
- When 2 main mesenteric vessels become occluded, surgical intervention is necessary
- Dreaded complications – bowel perforation, cardiac events, hemorrhage
- Partial cross clamping of the aorta is preferred
- Potential for intestinal infarction
- High risk of perioperative mortality _______(5)

Answer 37

Answers:
1. 20%
a. Nitro
b. Esmolol or Metoprolol
2. cautiously
3. 20%
4. atherosclerosis
c. acute embolic
5. 7-18%

Question 38

KATI Lower Extremity Revascularization
- May be performed traditionally or endovascular repair
- Hybrid operating rooms/cath labs perform these procedures
- Regional anesthesia may be appropriate for some patients
- GA, may use LMA if appropriate
- Must check if anticoagulation previously used
- Arterial lines +/- depends on length of surgery and patient _______(1)
- Three indications for surgery: _______(2), ______(a), and _______(3)
- May need possible amputation

• ______(b) of the graft for open lower limb procedures is the most stimulating part of the surgery
• Heparin is generally given
• Graft patency is evaluated carefully in the recovery room
• Keep patient warm and hydrated
• Avoid peripheral vasoconstriction
• ______(c) warrants return to surgery
  
  • Graft thrombectomy procedure may cause significant blood volume; need a T&C
• The postoperative period is when most cardiac issues occur

Answer 38

Answers:
1. comorbidities
2. claudication
a. ischemic ulceration
3. gangrene
b. Tunneling
c. Graft thrombosis