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Mar: Sem 7 - Adv. Principles C > Peripheral Vascular Anesthesia > Flashcards

Peripheral Vascular Anesthesia Flashcards

1
Q

Over 50% of Vasculopaths have this comorbidity.

A

CAD

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2
Q

Heparin is a naturally occurring anticoagulant produced by ____ and _______.

A
  • Basophils
  • Mast Cells
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3
Q

What does heparin bind to?

A
  • Antithrombin III
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4
Q

What happens to AT III when heparin is bound to it?

A

Enhances 1,000x the ability of AT III to inactivate thrombin and factors XII, XI, IX, X

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5
Q

Heparin will also inhibit thrombin activation of what factors?

A
  • Factor V
  • Factor VII
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6
Q

Heparin’s effect on platelet function

A

Inhibits platelet function

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7
Q

What factor does heparin effect on the extrinsic pathway?

A

Factor VII

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8
Q

What factor does heparin effect on the common pathway?

A

Factor V

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9
Q

Lipid solubility of heparin?

A

Poorly lipid soluble

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10
Q

GI absorption of heparin?

A

Poorly absorbed in the GI Tract

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11
Q

Does heparin cross the placenta?

A

No

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12
Q

Heparin’s anticoagulation increases in intensity and duration with increasing ________.

A

Doses

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13
Q

Heparin’s anticoagulation increases in intensity and duration with decrease ________, _____, and _______.

A
  • Temperature
  • Hepatic dysfunction
  • Renal dysfunction
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14
Q

CV side effects of heparin

A
  • Relaxation of vascular smooth muscle
  • Decreased MAP, Pulmonary arterial pressure, SVR
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15
Q

What is the most common side effect of heparin?

A

Hemorrhage

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16
Q

What is mild HIT due to?

A

Platelet aggregation

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17
Q

Plt count for mild HIT?

A

<100,000

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18
Q

When will mild HIT begin?

A

Appx 15 days after initiation of heparin therapy

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19
Q

What is the plt count for severe HIT?

A

< 50,000

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20
Q

When will severe HIT begin?

A

5-10 days after initiation

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21
Q

What antibody is formed with severe HIT?

A

IgG

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22
Q

What are the normal functions of IgG?

A
  • Neutralize toxins, viruses, and bacteria
  • Opsonize them for phagocytosis
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23
Q

How does IgG react with HIT?

A
  • lgG will bind to receptor on platelet
  • Lead to platelet activation
  • Activated platelets release pro-thrombotic substances (such as thrombin)
  • IgG activates more platelets

Key Takeaway: IgG antibodies in HIT cause the platelets to stick together and form clots

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24
Q

Heparin dose for Vascular Surgery

A

100 units/ kg

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25
Q

Normal aPTT and Heparinized aPTT

A
  • Normal aPTT: 30-35 seconds
  • Heparinized aPTT: 60-70 seconds
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26
Q

Normal ACT

A

90-120 seconds

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27
Q

When will you draw an ACT during a vascular surgery?

A
  • 3 minutes post heparin injection
  • repeat q 30 mins to 1 hour
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28
Q

What is the half life of heparin?

A

1-2 hours

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29
Q

Reversal for heparin

A

Protamine

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30
Q

Where can protamine be naturally found?

A

Salmon Sperm

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31
Q

MOA of Protamine

A

Protamine is a positively charged alkaline that combines with negatively charged (acidic) heparin

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32
Q

How is heparin naturally cleared in the body?

A
  • Reticuloendothelial system (RES)
  • Protamine clears heparin faster
33
Q

What is the dosage of protamine?

A

1 mg of protamine / 100 units of heparin

34
Q

Most common side effect of protamine

A

Hypotension d/t histamine release

35
Q

Who might be allergic to protamine?

A
  • Pt on chronic protamine insulin
  • Vasectomy
  • Fish allergies
36
Q

What reversal alternative can be used for patients undergoing vascular surgery if they are allergic to protamine?

A

Platelet factor 4

37
Q

What is a rare side effect of protamine?

A

Pulmonary Hypertension which will lead to pulmonary vasoconstriction, pulmonary edema, and hypoxia

38
Q

Pulmonary HTN from protamine is due to the secretion of ______ and ______.

A
  • Thromboxane
  • Serotonin
39
Q

If a patient is prone to pulmonary hypertension secondary to protamine what can be given as pre-treatment?

A

Cyclooxygenase Inhibitors (Indomethacin or ASA)

40
Q

At what GFR will symptoms be noted?

A

< 25mL/min

41
Q

What what GFR will a patient be dialysis dependent?

A

< 10 mL/min

42
Q

Most ESRD patient have their multisystem side effects controlled with _______.

A

Renal Replacement Therapy

43
Q

What are the metabolic abnormalities of ESRD?

A
  • Hyperkalemia
  • Hypermagnesemia
  • Hypocalcemia
  • Hypoalbuminemia
  • Water and sodium retention
  • Metabolic acidosis
44
Q

Hgb of ESRD patients

A

6-8 g/dL

45
Q

CV complication of ESRD

A
  • Increased cardiac output
  • HTN/CHF
  • Arrhythmias
46
Q

What is the increase minute ventilation of ESRD patients due to?

A

Increased minute ventilation to offset metabolic acidosis

47
Q

GI complications of ESRD

A
  • Nausea, vomiting, ileus
  • Hypersecretion of gastric acid
  • Delayed gastric emptying
48
Q

Neuro complications of ESRD

A
  • Lethargy, confusion
  • Peripheral neuropathies
49
Q

Pros of AV Fistulas

A
  • Best long-term patency
  • Lowest rate of infection
  • No foreign material used
50
Q

Cons of AV Fistulas

A
  • Requires a longer “maturation” time (6 weeks or more)
  • May require more than one operation to create a functional dialysis fistula
51
Q

Pros of AV Grafts

A
  • Shorter time required for “maturation”
  • Usually requires only one operation
52
Q

Cons of AV Grafts

A
  • Does not last as long
  • More prone to infections…complete removal
  • Embolectomies/revisions
53
Q

Anesthesia Pre-op Considerations for AV Fistulas/ AV Grafts

A
  • Day of surgery dialysis
  • Address cardiac/pulmonary issues
  • Consider ABG’s
  • EKG
  • Bleeding time/Coag studies
  • BUN, creatinine
  • Manage aspiration risk, hyperglycemia, hyperkalemia
54
Q

Anesthesia Intra-op Considerations for AV Fistulas/ AV Grafts

A
  • Access arm/blood pressure cuff
  • Consider invasive monitoring with uncontrolled HTN
  • Consider RSI for GA
  • Decrease dose of induction agents if hypovolemic/unstable
  • Maintain cardiac output
  • Adequate ventilation: spontaneous/controlled to prevent hypercarbia
55
Q

What fluids are usually preferred for ESRD patients?

A

Isolyte

56
Q

When would LR be avoided for ESRD patients?

A

If the patient is hyperkalemic

57
Q

When will NS will be used for ESRD patients?

A

If the patient is hypochloremic and alkalotic

58
Q

What drugs will have an increased effect on ESRD patients due to decreased protein binding?

A
  • Etomidate
  • Barbiturates
  • BZD
59
Q

What drugs will have an increased effect on ESRD patients due to elimination concerns?

A
  • Opioid metabolites
  • Anticholinergics
  • Metoclopromide
  • H2 blockers
  • Pancuronium
  • Neostigmine
  • Suggamadex
60
Q

What fraction of PAD patients are over the age of 75?

A

two-thirds of PAD population

61
Q

Clinical indication for revascularization surgery

A
  • Claudication
  • Ischemic rest pain
  • Gangrene (may be considered emergent d/t potential limb loss)
62
Q

Anesthesia Pre-op considerations for revascularization surgery.

A
  • History/Physical Assessment (CAD/COPD/CKD/DM)
  • Decreases or absent pulses
    bruits
  • Intermittent claudication
  • Rest pain
  • Hair loss
  • Temperature change
  • Doppler ultrasound
  • Ankle/brachial index
  • Angiography
  • Consider Type and Cross
63
Q

Ankle-brachial index formula

A

SBP at ankle / SBP at arm

64
Q

Ankle-brachial index for rest pain

A

0.4

65
Q

Ankle-brachial index for impending gangrene

A

0.25

66
Q

Normal Ankle-brachial index

A

0.9-1.4

67
Q

What does an ankle-brachial index > 1.4 indicate?

A

Calcification/ Vessel Hardening

68
Q

Ankle-brachial index that indicates severe arterial disease

A

Less than 0.5

69
Q

Treatment of PAD

A
  • Stop smoking!!!
  • Normalization of blood sugars
  • Treatment of hypertension
  • Antiplatelet therapy
  • Revascularization
70
Q

What are the types of revascularization procedures?

A
  • Angioplasty
  • Stenting
  • In-situ bypass
  • Synthetic bypas
71
Q

PAD patients requiring angioplasty and stenting through these arteries have a high success rate.

A

Iliac arteries

72
Q

PAD patients requiring angioplasty and stenting through these arteries have a low success rate and are prone to restenosis.

A

Femoral/popliteal arteries

73
Q

How long does a revascularization stent last?

A

10 years

74
Q

Regions that warrant an in situ bypass

A
  • Femoral-popliteal
  • Femoral-tibial
75
Q

Regions that warrant a synthetic graft bypass

A
  • Aorta-bifemoral
  • Axilla-bifemoral
  • Femoral-femoral (fem-fem crossover)
76
Q

Anesthesia Intraop consideration for Femoral-popliteal and Femoral-tibia bypass.

A
  • Few concerns
  • Little blood loss
  • Sometimes heparin is not reversed
  • 45 minute procedure
77
Q

Anesthesia Intraop consideration for Aorta bi-fem/Axillo bi-fem/fem-fem crossover

A
  • Type and cross
  • Large bore IV access
  • Central line/SVV monitoring
  • Large blood loss may occur
  • Heparin often redosed and usually reversed
  • 2-4 hour procedure
78
Q

Anesthesia Post-op Concerns for Revascularization Surgery

A
  • Sudden loss of pulses
  • Sudden temperature change
  • Complaints of numbness/paresthesia
  • Loss of motion/sensation

Mar: Sem 7 - Adv. Principles C (11 decks)

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