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Co-Existing & Basic Principles 2016 * > PVD > Flashcards

Flashcards in PVD Deck (17):
1

What is PVD

  1. Compromised blood flow to the extremities
  2. Ankle-brachial index of less than 0.9
    • Ratio of SBP in ankle vs SBP in brachial artery

2

What causes PVD

  1. Atherosclerosis- most common cause
    • goes hand in hand with CAD
  2. Arterial embolism- acute cause
  3. Vasculitis - inflam of vasculature

3

Is someone has PVD, it can be assumed that they likely have ___

Over what age can it be assumed that someone has PVD

CAD

Over 75 y.o. (exceeds 70%)

4

Atherosclerosis risk factors

  1. DM
  2. Advanced age
  3. Male gender
  4. Obesity/Inactivity
  5. HTN
  6. Smoking
  7. HLD
  8. Hyperhomocysteinemia
  9. Family Hx of early atherosclerosis

5

Atherosclerosis s/s

  • Intermittent claudication → most common symptom
    • pain that starts with walking/exercise and stops with rest
  • cool/cold feet leg pain while lying flat
    • relieved by sitting
    • sign of advanced disease
  • loss of pulses in feet/legs
  • pale color in legs when raised
    • dependent rubor - redness in dependent position
  • shiny skin
  • loss of hair on feet
  • thinckened toenailsmay have fungal infection
  • critical limb ischemia
    • Most severe symptom 
    • "rest pain"
    • lack of O2 to the limb at rest
    • associated with non-healing ulcers & gangrene

6

Diagnostic tests for atherosclerosis

  1. Doppler Ultrasonography
  2. Ankle/Brachial Index
    • Normal index is 0.95 at rest
    • = claudication
    • = pain with resting
    • = ischemic ulceration or impending gangrene
  3. Duplex Ultrasonographic Scan
  4. Transcutaneous oximetry
    • 60 mm/Hg = Normal
    • in patients with limb ischemia
  5. MRI
  6. Contrast angiography - locates blocked area

7

 atherosclerosis treatment

  1. LIfestyle modification
    • exercise, weight loss, smoking cessation
  2. Lipid-lowering medications
    • statin drugs
  3. Vitamin C, E, folate
  4. Antiplatelet therapy
  5. Revascularization
    • PTA w/stent, Bypass, Intra-arterial thrombolytic therapy, balloon embolectomy, endarterectomy
  6. Amputation :-(

8

Surgical approach to Peripheral Revascularization

  • Donor and Recipient arteries are exposed and a tunnel is created for a bipass graft
  • Graft either Saphenous vein or prosthesis
  • Heparin given IV
    • must note the time (3-5 min onset)
    • Still able to use regional anesthesia (dose 3000-5000)
  • Anastamosis is made
  • Arteriogram to confirm flow
  • Heparin is usually NOT reversed

9

Giving what drug during revascularization will likely get you sent home for the day

Phenylephrine

Don't get sent home for the day.

10

Impact of PVD on anesthetic management

  1. Principal risk - athlerrosclerosis and ischemic heart disease
  2. Patients with PVD have 3-5x greater risk of stroke, MI and death
  3. On patents who experience angina and claudication CABG is usalully done prior to revascularization surgery

11

Anesthetic management for a pt with PVD

  • Treat it like CAD, which they probably also have
  • No hypo/hypertension, no tachycardia
  • Risk can be reduced if pt has already had a CABG to treat CAD

12

Risks with revascularization

  • Hemorrhage
  • Infection
  • Pulmonary embolism (watch ETCO2)
  • MI
  • Low CO--> ischemia
  • Pulmonary edema
  • Risks associated with the lithotomy position - nerve palsy, limb ischemia

13

Monitoring  and anesthetic management for peripheral revascularization

  1. consider co-morbidities (they often have CAD, diabetes, HTN)
  2. Preop → make sure pt takes beta-blockers and/or other chronic medication

  3. Intra-op A-line and CVP or foley to monitor fluid volume status

    1. Ability to monitor end organ perfusion & oxygenation

    2. Estimate blood loss and 3rd space fluid loss

    3. Watch coags, electrolytes, and pH changes (Blood gasses)
    4. Cross-clamp (note time -  limb not receiving blood from that moment on)
    5. heparin admin - make sure to note time of admin(peaks in 3-5min)

14

Anesthetic management for peripheral revascularization 

​Regional is preferred

  • Increased graft blood flow (grafts do better)
    • spinal is preferred - less hematoma risk
  • Less increase in SVR with cross-clamping (sympatectomy)
  • Better Postop pain relief (​less SNS outflow and less vasoconstriction)
  • Less activation of the coagulation system
    • less risk of grafts clotting and having to return to the OR
    • decreased SNS outflow = less inflammation
  • ​Make sure to check INR and platelets prior to regional
  • There is NO difference if CV complications with regional vs GA
    • ​BUT there is a SIGNIFICANT difference in complication rate of GRAFT OCCLUSIONS
    • General hage an increased risk of occlusions!!!

15

In revascularization which is prefered, spinal or epidural?

Spinal

higher risk of hematoma with epidural

16

What advantage has been shown with regional vs general in revascularization

Regional has improved outcomes for graft occlusion, but shows no benefit in terms of cardiopulmonary complications

17

PVD

Regional vs. General? 

  • Assess for coagulopathy
  • General is indicated for pts in which heparin therapy has already been started
  • Regional is a good consideration b/c:
    • has lower incidence of post-op graft occlusion, this is r/t ↓SNS outflow which ↓circulating catecholamines, vasodilation, and ↓ blood viscosity r/t fluid volume loading
    • If considering regional, spinal may be better choice over epidural to avoid hematoma (much smaller needle)
    • Studies have shown no difference btw RA & GA in terms of cardiopulmonary complications
  • Monitoring
    • pt's present w/other co-morbidities (CAD,DM,HTN)-degree of monitoring depends on sx & extent of dz
    • Consider use of a-line (good documentation that an assessment of collateral flow has been performed esp w/co-existing microvascular disease such as Reynaud's)
    • consider need to monitor intravascular volume (CVP, Swan, or simply via foley - the "poor man's Swan")
    • Initial revascularization procedures generally have minimal blood loss & minimal third space loss
  • Pre-op
    • make sure pt's take beta blockers or other chronic meds such as antihypertensives (except ACE-inhibs)
  • Post-op
    • provide adequate analgesia to prevent ↑SNS stim & therefore maintain graft patency
    • can use Precidex (dexmedetomidine) an alpha-2 agonist to attenuate ↑HR & NE release during emergence or extubation (less sedating than propofol but can cause marked hypotension & bradycardia) Dose = 0.2-0.7 mcg/kg IV