Anesthesia for Vascular Surgery

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Anesthesia for Vascular Surgery
2014-02-15 18:40:20
BC Nurse Anesthesia CP2

Anesthesia for Vascular Surgery
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  1. Major risk factor for PVD
  2. Atherosclerosis is an _______ process.
    inflammatory, body recognizes LDL as a foreign substance, get pro-inflammatory cytokines
  3. Tell me about coronary artery plaques  Ie- stable or unstable?, rupture or occlude?
    • Unstable and prone to rupture
    • Thin cap with thick lipid core
  4. Tell me about carotid artery plaques- ie stable or un?, rupture or occlude?
    • Unstable, more likely to occlude
    • Thin cap with thick lipid core (like coronary plaques)
  5. common sites for plaque lesions
    • bifurcations!  turbulent flow, high pressure, vessel wall shearing
    • coronary arteries 
    • carotid bufurcation
    • abdominal aorta
    • illiac arteries
  6. PVD s/sx
    • 50% have none or mild s/sx
    • claudication
    • numbness or weakness of LE
    • Cold legs/ feet
    • Non healing ulcers
    • Hair loss on legs, shiny skin
    • Impotence
  7. What are the 3 theories explaining PVD?
    • Virchow's- endothelial injury is caused by physical and enviro factors, sub endothelium is exposed, smooth muscle proliferation and Plt adherence occurs
    • Monoclonal- cell proliferates 2/2 a mutagen or virus
    • Clonal senescence- smooth muscle proliferation inhibition decreases with aging
  8. What is an aneurysm?
    localized dilation or out-pouching of a vessel wall
  9. Why is the aorta particularly susceptible to aneurysms?
    • High constant stress to vessel wall
    • Absence of penetrating vasa vasorum in the adventitial layer
  10. Major causes of aneurysms
    • HTN and atherosclerosis
    • Genetic component, most have a 1st degree relative who also has it
  11. What is systemic vasculitis?
    blood vessel inflammation (caps, arteries, and veins)
  12. S/sx vasculitis
    • fever
    • wt loss
    • fatigue
    • muscle and joint pain
    • loss of appetite
  13. Implications of vasculitis
    Can rx blood flow to organs causing major damage
  14. Systemic vasculitis: Buerger's dz
    • inflammation and clots in BV of arms and legs
    • assoc with cigarette smoking
    • typically occurs in middle aged jewish males
  15. Systemic vasculitis: Takayasu's arteritis
    • includes largest arteries in the body, including the aorta
    • typically occurs young asian females
  16. Systemic vasculitis: Kawasaki disease
    • most often affects kids < 5 yo
    • s/sx: fever, rash, eye inflammation
  17. Systemic vasculitis: Giant cell arteritis / temporal arteritis
    • Usually occurs in ppl > 50 yo
    • Inflammation of arteries in neck, upper body, arms, and head (esp. the temples)
    • Most common vasculitis in US
    • Assoc with PMR
    • Tx= corticosteroids
    • S/sx= H/A, scalp tenderness, jaw pain, blurred vision, blindness
  18. Systemic vasculitis: Raynaud's
    • cold induced arterial spasm of the extremities
    • Often found in adult females
    • Assoc with SLE and scleroderma
    • Avoid VC with regional anesthesia
  19. Systemic vasculitis: Wegener's granulomatosis
    • inflammation of blood vessels in nose, sinuses, throat (URI), lungs, and kidneys
    • s/sx= SOB, nosebleeds, nose ulcers
    • Pts may be immunosuppressed due to tx with cyclophosphomide
  20. Systemic vasculitis: polyarthritis nodosa
    • affects medium sized BV in many different parts of the body
    • most common in F, ages 20-60
    • s/sx= purpura, ulcers, muscle and joint pain, abd pain, HTN
  21. Systemic vasculitis: Moyamoya disease
    • narrowing or occlusion of both IC arteries
    • may cause TIAs in kids and IC hemorrhage and IC aneurysms in adults
  22. CAD risk in pts having vascular surgery
    < 10% have normal coronaries
  23. Intermediate clinical predictors of increased peri-op CV risk (MI, HF, and death)
    • mild angina
    • previous MI
    • CHF
    • DM
    • CRI (Cr > 2)
  24. Minor clinical predictors of increased peri-op CV risk (MI, HF, and death)
    • adv age
    • abn EKG
    • Rhythm other than sinus
    • Low func. capacity
    • H/O CVA
    • Uncontrolled HTN
  25. Major clinical predictors of increased peri-op CV risk (MI, HF, and death)
    • Unstable coronary syndrome (acute or recent MI), unstable or severe angina
    • Decomp HF
    • Signif arrhythmias (high grade AVB, symptomatic vent arrhythmias, uncontrolled SVT)
    • Severe valvular disease
  26. Most common cause of peri-op death with vascular surgery
    • MI
    • usually occurs post-op (but we play a role with our emergence and wake-up)
  27. When in the vascular surgery peri-op period to most MIs occur ?
    24-48 hour period
  28. T or F, vascular surgery is considered intermediate risk
    F, it's high risk
  29. Why is peripheral vascular surgery reserved for severe ischemia?
    Limited durability of bypass graft
  30. What is the ankle/ arm index?
    • Used to evaluate severity of arterial insufficiency
    • Compare BP on arm and on calf
    • Normal- ratio = 1 (they are equal)
  31. What type of vascular surgery involves aortic cross clamping?
    Aortofem bypass
  32. Factors to be avoided post-op for prevention of MI with vascular surgery
    • tachycardia
    • hypothermia
    • hypervolemia
    • pain
  33. Adv / disadv of use of regional anesthesia in vascular surgery
    • IV anticoag must be stopped prior to regional
    • Stable HD with incremental dosing
    • Improved graft patency
    • limited duration (case may be long)
    • thoracic epidurals are difficult to place
    • risk sympathectomy
  34. Adv / disadv of use of general anesthesia in vascular surgery
    • pt can stay on IV anticoag
    • able to graft UE
    • hypercoagulable state
    • increased post-op catecholamines
    • possible ventilatory challenges post-op (abd surgery)
  35. Neuraxial level needed for vascular surgery
    • T10-T12
    • T8 if exposing the pelvis
  36. Major risks associated with CEA
    MI and CVA
  37. For what degree of ICA narrowing is CEA beneficial
    • 60-90%
    • No benefit in pts with < 60% narrowing
  38. T or F, its with LM CAD are more likely to have carotid disease
  39. S/sx carotid stenosis
    TIA, CVA, UE or LE numbness or weakness, unilateral monocular blindness
  40. What type of CVA is likely to occur with a CEA
  41. Increased risk of poor neuro outcome is seen in its undergoing CEA with what issues?
    • Poor collaterals
    • Contralateral carotid occlusion
    • Renal insufficiency, (Cre > 2)
    • Poorly controlled HTN
    • CAD requiring bypass
    • Decreased LOC pre-op
    • Active neuro process pre-op
  42. The glossopharyngeal nerve (CN 9) runs alongside what structures?  What are the implications?
    • Of concern with a CEA
    • Runs along side ICA, where the carotid body and sinus are located
    • Damage to carotid body- insensitivity to hypoxia
    • Damage to carotid sinus- vagal response (baroreceptor)
  43. 2 major vessels supplying the brain
    IC and vertebral artery
  44. What structure provides collateral circulation to the brain?  How does it work?
    circle of willis, so if either the IC or vertebral artery is occluded, brain still receives adequate flow
  45. Goal ETCO2 for CEA, why?
    • normocarbia
    • avoid steal as thick stenotic vessels aren't affected by CO2 level so blood is directed away from areas that need it
  46. Anesthetic agent selection for CEA
    • short acting to allow a smooth and fast wakeup
    • assess neuro status
    • avoid coughing and bucking with emergence
  47. Goal fluid management for CEA
  48. What factors can increase myocardial O2 demand?
    Increase in: HR, diastolic volume, contractility, BP
  49. What factors can decrease myocardial O2 supply?
    • Decrease in coronary blood flow (incr HR, diastolic volume, coronary VC or thrombosis)
    • Decrease in O2 content (decr Hct or O2 sat)
  50. Goal BP for CEA
    20% ABOVE baseline
  51. Normal cerebral blood flow
    50 ml / 100g brain
  52. Factors that will affect EEG with CEA
    propofol, volatiles, bovie
  53. How is an awake CEA performed- what's the benefit
    • With a carotid plexus block (C2-4)
    • Adv= Constant neuro assessment
  54. T or F, use of carotid plexus block is associated with a decrease in post-op CVA incidence
    F, no difference with regional vs. GA
  55. contraind to regional anesthesia for CEA
    • high carotid lesion
    • language barrier
    • claustrophobia
    • pt preference
  56. Adv of using GA for CEA
    • ability to manip HD
    • decrease O2 demand and catecholamine level
    • airway security
  57. Can N20 be used for a CEA
    Yes, however there's a risk of air exposure with shunt placement and during release of cross clamp- so if using shut it off prior
  58. Risks associated with CEA
    • Damage to recurrent laryngeal nerve
    • CVA
    • Carotid body denervation
    • Hyperperfusion syndrome (HA, sz, vision changes)
  59. T or F, barbs and etomidate are known to be cerebral protectant and are rec for use with CEA
  60. Risk of AAA rupture increases with diameter of ____.
    > 4.5- 5 cm
  61. Elective repair of AAA is indicated with a diameter of ____ or _____.
    • 6 cm or greater
    • > 0.5 cm increase in 6 mo or symptomatic
  62. Risk factors for AAA
    • adv age
    • smoking > 40 yrs
    • HTN
    • incr LDL
    • low Plt count
    • atherosclerosis
    • more prevalent in males
  63. CV changes assoc with aortic cross clamping for AAA repair
    • Increased MAP and SVR
    • Slight decrease in CO
    • Decreased O2 consumption 
    • Preload may increase with myocardial dysfunction
    • MI
  64. Interventions to counteract CV changes assoc with aortic cross clamping
    vasodilators (nitroprusside, fenoldapam, volatiles, NTG, BB)
  65. Metabolic changes assoc with aortic cross clamping for AAA repair
    • decreased total body O2 consumption (above and below clamp)
    • decreased CO2 prod
    • incr epi and NE
    • resp alk
    • met acidosis
  66. T or F, renal blood flow is preserved with infra-renal aortic cross clamping?
    F, RBF is decreased
  67. Strategies to maintain renal perfusion with AAA repair
    • euvolemia (optimize pre-op)
    • mannitol
    • lasix
    • dopa
    • mucomyst
    • fenoldopam
  68. Coagulation changes assoc with aortic cross clamping
    • Clotting factor consumption, can get DIC 
    • Hypocalcemia
    • Thromboxane causes increased vasc permeability leading to pulm edema
  69. artery of adamkiewicz
    • risk of damage with AAA repair
    • can lead to SC ischemia
    • joins anterior spinal artery btw T8-12
  70. Goal BP with aortic dissection /  decr thoracic aneurysm
    SBP 90-120 mmHg
  71. What type of endoleaks are the most concerning and why?
    • Type 1 and 3
    • assoc with incr risk of rupture, require aggressive tx
    • both involve leaking with forward flow of blood into aneurysm sac
  72. Which procedure is safer open or endovascular AAA repair
  73. Possible post-op complication of desc thoracic aneurysm
    post-op paraplegia due to interruption of blood flow from artery of adamkiewwicz
  74. What is the mainstay of tx for AAA repair
    volume and fluid replacement
  75. Why is it difficult to estimate EBL with AAA repair surgery
    due to the venous capacitance of the splanchhic circulation
  76. therapeutic interventions with aortic cross clamp release
    • volume
    • neo
    • calcium
    • ephedrine
    • epi
    • Na bicarb
    • incr MV