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Concepts 2 > Anesthesia for Vascular Surgery > Flashcards

Anesthesia for Vascular Surgery Flashcards

1
Q

Major Co-existing diseases of PVD

A

Coronary artery disease
May require preoperative coronary revascularization
COPD
Hypertension
Renal insufficiency
Uncontrolled Diabetes
Liver disease

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2
Q

____________ remains the single most important cause of morbidity following vascular surgery

A

Myocardial dysfunction

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3
Q

Goals of Vascular Anesthesia

A

Minimize patient morbidity and maximize surgical benefit
Considerations: CNS – Renal – Liver – Gut

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4
Q

Predictors of M&M after vascular surgery

A

Low serum albumin levels
ASA status (comorbid conditions)

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5
Q

Perioperative Monitoring Goals
for vascular surgery patients

A

Detect myocardial ischemia
Identify abnormalities
Preload -afterload -ventricular function

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6
Q

Pharmacologic Interventions for Vascular Surgery

A

** beta-blockers** (metoprolol -atenolol –esmolol)
alpha-2 agonists (pretreatment with clonidine 300 mcg 90min before surgery)
Calcium channel blockers (diltiazem – Clevidipine)
**Nitroglycerin **(used to treat arterial hypertension, elevated cardiac filling pressures and vasospasm)

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7
Q

Patho of the chornic inflammation in vascular disease

A

Adhesion molecules
Leukocytes: Lipid accretion & vasculitis
Markers of inflammation
High-sensitivity C-reactive protein (hs-CRP)

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8
Q

Major risk factors for chronic inflammation in vascular disease

A

Metabolic syndromes - insulin resistance - DM – pro-inflammatory state - HTN - Abd. Obesity
**Cigarette smoking **(vaping, marijuana ect.)
**Elevated LDL-C **(low-density lipoprotein-cholesterol: “bad” chol. )
Small LDL particles increase CAD risk
Penetrate endothelial barrier 2X more than large particles
Associated with high triglycerides, Low HDL, metabolic syndromes
**Low HDL ** (high-density lipoprotein: “good” chol. )
Absorbs and transports to the liver
High levels are best
Genetics
Aging

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9
Q

Pathophysiology of Atherosclerosis

A

Generalized inflammatory disorder
Endothelial dysfunction
Vaso-protective effects - Nitric Oxide
Formation of intimal plaques
Oxidative lipids -inflammatory cells -smooth muscle cells -connective tissue fibers -calcium deposits
Endothelial damage
Inflammation
Hypercoagulability
Low-density lipoproteins
Vasoactive influences

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10
Q

Medical Management of Atherosclerosis

A

Antihypertensives
beta-blockers - ACE inhibitors
Statin drugs
Antiplatelet
ASA - Plavix - glycoprotein Iib/IIIa inhibitors
Cessation of smoking

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11
Q

Normal Cerebral Vascular System and its disease state

A

Cerebral Blood Flow & Metabolism
* Primarily responsible for the Delivery of O2 and glucose
Cerebral circulation (CBF)
* Internal carotids arteries give 80% of flow to the head
* Vertebral arteries give 20% of flow to the head
* Collateral channels come off of these

Auto-regulated: CBF/CMRO2 coupling they match each other. They are in balance and go up and down together.
* To match cerebral metabolic rate of oxygen CMRO2
3 ml O2 to every 100Gm brain flow per min
* Coupled: increased and decreased together
* In which situations are they Uncoupled? (pathology/medications)

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12
Q

Carotid Disease

A

Bilateral in about 1/2 of all cases
Atherosclerotic plaque - Lateral aspect of the bifurcation and extends into the internal and external arteries
Primarily a problem of embolization
May manifest as asymptomatic bruit or Amaurosis fugax (monocular transient blindness)
TIA vs RIND (resolution 24 vs > 24hrs)

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13
Q

Carotid Disease

A

Bilateral in about 1/2 of all cases
Atherosclerotic plaque - Lateral aspect of the bifurcation and extends into the internal and external arteries
Primarily a problem of embolization
May manifest as asymptomatic bruit or Amaurosis fugax (monocular transient blindness)
TIA vs RIND (resolution 24 vs > 24hrs)

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14
Q

TIA =

A

Transient ischemic attack
Can last 2-15 minutes or up to 24 hours

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15
Q

RIND =

A

Reversible Ischemic Neurologic Deficit
Can last up to 7 days

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16
Q

Stroke in evolution AKA ___

A

Progressive Stroke
(stroke with neurological deficits that continue to worsen for hours or days after onset)

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17
Q

Completed stroke

A

Established neurological deficit that is irreversible or only partly reversible

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18
Q

Anesthetic Goals for Carotid Endartarectomy

A
  • Prevention and prompt detection of cerebral and myocardial ischemia
  • Maintenance of hemodynamic stability
  • Rapid recovery from anesthetic drug effects for prompt evaluation of neurologic function
19
Q

Clinical Focal Neurological Signs

A
  • Presentation – contralateral
  • Weakness and numbness
  • Dysphasia, dyspraxia, and confusion (dominant hemisphere), transient
  • Blurring of vision or blindness
    (Ipsilateral eye), homonymous visual field loss; ipsilateral headache
20
Q

Appropriate Candidates for Carotid Endartarectomy

A
  • Symptomatic 70-99% stenosis
  • TIAs or non-disabling stroke
  • Surgically accessible stenosis
  • Stable medical condition
21
Q

Inappropriate Candidates for Carotid Endartarectomy

A
  • Asymptomatic <60% stenosis
  • Symptomatic or asymptomatic with
  • Intracranial stenosis more severe than the extracranial stenosis
  • Uncontrolled DM, HTN, CHF, Unstable Angina
  • A major neurologic deficit or decreased LOC
22
Q

Uncertain candidates for a CEA (carotid endartarectomy)

A

Symptomatic <70% stenosis
TIAs or nondisabling stroke
Surgically accessible stenosis
Stable medical and neurologic condition
Asymptomatic >60% stenosis
Surgically accessible stenosis
Stable medical condition

23
Q

Pre-anesthetic assessment for CEA

A
  • State of health
    History, physical exam and chart review
  • Coexisting diseases
    CAD, HTN, PVD, COPD, CRI, and DM
  • Adverse affects from hyperglycemia
  • Cardiac complications
    CHF and MI
  • Cerebral Angiogram
    Contralateral carotid disease or poor collaterals
  • Risk stratification scheme
24
Q

Formula for CBF

A

Cerebral Blood Flow
CPP/CVR (Cerebral Vascular Resistance)

25
Q

Formula for CPP

A

Cerebral Perfusion Pressure
MAP minus ICP or CVP (whichever value is greater)

26
Q

What are determinants of CVR?

A

Blood viscosity
Diameter of resistance vessels

27
Q

How do we optimize CBF during CEA?

A

Arterial BP control
Arterial CO2 tension

28
Q

Strategies to mitigate cerebral and myocardial Ischemia

A

Hyperventilation
Creates an Inverse steal aka Robinhood effect
Decreased Co2->vasodilation to focal ischemia areas
* Carotid shunt
Blood Pressure
Consider baseline
Essential HTN
*Temperature *
Neuroprotective vs myocardial ischemia

29
Q

With preexisting chronic hypertension,
the autoregulation curve is _____.

A

shifted

30
Q

During carotid cross-clamp CBF response to PaCO2 is _____.

A

impaired and dependent on CPP

31
Q

BP goals during CEA

A

BP within normal preoperative range (170/90?)
Some clinicians prefer 10 – 20% above baseline

32
Q

Superficial cervical plexus block

A

Subcutaneous local in posterior border of sternocleidomastoid (lateral neck)
Cutaneous branches of the plexus fan out to innervate the skin

33
Q

Deep cervical plexus block

A

Paravertebral block of C2-4 nerve root
Intravascular compilations

34
Q

PEARLs for regional anesthesia

A

Intraoperative monitors
Basic monitoring
Arterial line
+/- Cerebral oximeter
**Supplemental O2 **
mask or nasal cannula (risks)
Sedation for block
Fentanyl and midazolam
Sedation for case: Consider assessment
Dexmedetomidine
Propofol (after CNS assessment)
Be prepared for conversion to GA

35
Q

Advantages of Regional Anesthesia with vascular surgery

A

Superior neurologic monitoring while awake
Technically a simple block
Intubation not required
Potential to minimize interventions (shunt)
Less expensive
Blunts catecholamine responses
Reports of more rapid recovery and shorter hospitalization
Provides postoperative analgesia

36
Q

Disadvantages of regional anesthesia during vascular surgery

A

Patience and gentle technique
Reinforcement of block
Lack of airway and ventilatory control
Complication
Stroke – TIAs – cross clamp intolerance – seizure – airway obstruction – confusion – hypoventilation – agitation – angina
LA toxicity
Subarachnoid injection
Vertebral artery injection
Phrenic nerve injury
Recurrent laryngeal nerve injury
Horner’s Syndrome (30-45 min after block)
Ipsilateral Ptosis (lid), myosis (pupil)

37
Q

Monitors and Meds to use during vascular durgery with GA

A

Intraoperative Monitors
Arterial catheter
ECG
Pulse oximetry and capnography
CVP or PCWP (high risk)
Cerebral oximeter
Multimodality monitoring
Maintenance of hemodynamic stability
ETCO2: Normocapnia

Pharmacologic
+/- Midazolam – Propofol – Etomidate - Dexmedetomidine
Opioids
Nondepolarizing NMB (avoid Sch)
Volatile anesthetic (nitrous oxide is controversial)

38
Q

Advantages of GA with vascular surgery

A

Potentially more comfortable
Controlled ventilation
Management of complications
X-clamp intolerance and transient ischemia
Reduces the need for expedience
Cerebral protection???

39
Q

Disadvantages of GA with vascular surgery

A

Need for an alternative method for monitoring cerebral function
Hemodynamic instability
Difficult to detect neuronal damage
Prolonged emergence
Confused postoperative assessment
More expensive

40
Q

Step before carotid cross clamping and type of monitoring

A

Prior To Clamp give (75 – 100 Units/Kg) Heparin

Increased BP above the clamp and decreased below the clamp
Neurologic Monitoring happens during this time
* Awake Patient
* EEG
* Stump Pressures
* Cerebral Oximeter
* TCD (transcranial doppler)

41
Q

Interventions In Response To Evidence Of Cerebral Ischemia

A

Increasing CPP (Vasopressor)
Suppress CMRO2 (Controlling Anesthesia for a nice calm state - Etomidate…)
Restore Internal Carotid Artery Blood Flow
Shunt may be needed- the rate of shunting is decreased with regional anesthesia

42
Q

Emergence from GA after CEA and postop management

A

Avoid excessive coughing or straining and increased BP
Hematoma risk: Assess and document yourself
Heparin reversal controversial (surgeon to surgeon- have the conversation)
Awake and extubated for neurologic examination before you move the patient
Close monitoring of ventilatory status
Hemodynamic stability

43
Q

Potential Complications of CEA

A

MI
Dysrhythmia – AF
Hypoxia and Hypercarbia
Pneumothorax
Pain
Distension of Bladder

44
Q

Perioperative complications by order of incidence for vascular surgery

A

Hypertension
Hypotension
Crnaial nerve injury
Stroke
Wound hematoma
MI

Concepts 2 (11 decks)

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