PVD Flashcards
What is PVD
- Compromised blood flow to the extremities
- Ankle-brachial index of less than 0.9
- Ratio of SBP in ankle vs SBP in brachial artery
What causes PVD
- Atherosclerosis- most common cause
- goes hand in hand with CAD
- Arterial embolism- acute cause
- Vasculitis - inflam of vasculature
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%)
Progression of atherosclerotic lesions
- Fibrous plaque →
- calcium accumulation →
- Endothelium disruption →
- platelet thrombus formation →
- hemorrhage into lesion
Atherosclerosis risk factors
- DM
- Advanced age
- Male gender
- Obesity/Inactivity
- HTN
- Smoking
- HLD
- Hyperhomocysteinemia
- Family Hx of early atherosclerosis
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 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
Diagnostic tests for atherosclerosis
- Doppler Ultrasonography
- 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
- Duplex Ultrasonographic Scan
- Transcutaneous oximetry
- Normal is 60 mm/Hg
- <40 mm/Hg in patients with skin ischemia
- MRI
- Contrast angiography
Tx atherosclerosis
- LIfestyle modification
- exercise, weight loss, smoking cessation
- Lipid-lowering medications
- statin drugs
- Vitamin C, E, folate
- Antiplatelet therapy
- Revascularization
- PTA w/stent, Bypass, Intra-arterial thrombolytic therapy, balloon embolectomy, endarterectomy
- Amputation :-(
Indications for revascularization
- 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
Giving what drug during revascularization will likely get you sent home for the day
Phenylephrine
Don’t get sent home for the day.
Does heparinization during revascularization preclude the use of regional anesthesia?
Usually still OK as only 3000-5000 units will be given during the procedure
What is the primary risk during revascularizatiom
3-5x greater risk of MI, stoke, and death in a pt with atherosclerosis
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
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
Monitoring consideration for revascularization
- 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 3rd 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
Benefits of regional in revascularization
- 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
In revascularization which is prefered, spinal or epidural?
Spinal
higher risk of hematoma with epidural
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
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
