PVD

Question 1

What is PVD

Answer 1

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

Question 2

What causes PVD

Answer 2

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

Question 3

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

Over what age can it be assumed that someone has PVD

Answer 3

CAD

Over 75 y.o. (exceeds 70%)

Question 4

Progression of atherosclerotic lesions

Answer 4

1. Fibrous plaque →
2. calcium accumulation →
3. Endothelium disruption →
4. platelet thrombus formation →
5. hemorrhage into lesion

Question 5

Atherosclerosis risk factors

Answer 5

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

Question 6

Atherosclerosis s/s

Answer 6

• 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 toenails
  
  • _{may have fungal infections}
• critical limb ischemia
  
  • _{Most severe symptom}
  • _{“rest pain”}
  • _{lack of O2 to the limb at rest}
  • _{associated with non-healing ulcers & gangrene}

Question 7

Diagnostic tests for atherosclerosis

Answer 7

1. Doppler Ultrasonography
2. Ankle/Brachial Index
   
   • Normal index is .95 at rest
   • <0.9 = claudication
   • <0.4 with rest pain
   • <0.25 with ischemic ulceration or impending gangrene
3. Duplex Ultrasonographic Scan
4. Transcutaneous oximetry
   
   • Normal is 60 mm/Hg
   • <40 mm/Hg in patients with skin ischemia
5. MRI
6. Contrast angiography

Question 8

Tx atherosclerosis

Answer 8

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 :-(

Question 9

Indications for revascularization

Answer 9

• Acute ischemia due to emboli, thrombus, pseudoaneurysm from femoral a-line
• Must be corrected within 4-6 hours to prevent ischemia/infarct
• Chronic ischemia from plaque progressing to claudication

Question 10

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

Answer 10

Phenylephrine

Don’t get sent home for the day.

Question 11

Does heparinization during revascularization preclude the use of regional anesthesia?

Answer 11

Usually still OK as only 3000-5000 units will be given during the procedure

Question 12

What is the primary risk during revascularizatiom

Answer 12

3-5x greater risk of MI, stoke, and death in a pt with atherosclerosis

Question 13

Anesthetic management for a pt with PVD

Answer 13

• 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

Question 14

Risks with revascularization

Answer 14

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

Question 15

Monitoring consideration for revascularization

Answer 15

• consider co-morbidities
  
  • _{they often have CAD, diabetes, HTN}
• Preop- make sure pt takes beta-blockers and/or other chronic medication
• A-line, intra-op ok CVP or foley to monitor fluid volume status
• monitor end organ perfusion & oxygenation
• Estimate blood loss and 3^rd space fluid loss
• Watch coags, electrolytes, and pH changes
• Cross-clamp
  
  • _{note time - limb not receiving blood from that moment on}
• heparin admin - make sure to note time of admin
  
  • _{Heparin peaks in 3-5min}

Question 16

Benefits of regional in revascularization

Answer 16

• Increased graft blood flow
  
  • grafts do better with regional
  • spinal is preferred - less hematoma risk
• Less increase in SVR with cross-clamping
  
  • d/t sympatectomy with the regional
• Postop pain relief
• Less activation of the coag system
  
  • less risk of grafts clotting and having to return to the OR

Question 17

In revascularization which is prefered, spinal or epidural?

Answer 17

Spinal

higher risk of hematoma with epidural

Question 18

What advantage has been shown with regional vs general in revascularization

Answer 18

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

Question 19

PVD

Regional vs. General?

Answer 19

• 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}