CHAPTER 61 ARTERIAL OCCLUSION Flashcards
Pain at rest, ulceration or gangrene exists
CRITICAL LIMB ISCHEMIA
Most important risk factors for PAD
Smoking and DM
Others: hyperlipidemia, hypertension, elevated blood homocysteine, elevated CRP
Most frequently diseased arteries
For The ABc
Femoropoplitieal
Tibial
Aortoiliac
Brachiocephalic
Pathophysiology of Acute Limb Ischemia
Sudden decrease in blood supply to a limb –> tissue hypoperfusion and threatening limb viability
Irreversible changes occurs within how many hours of vessel occlusion due to absence of collateral vessels
4 - 6 hours
What can happen following restoration of blood flow
REPERFUSION INJURY
- compartment syndrome, rhabdomyolysis, metabolic derangements
Most common cause of Acute Limb Ischemia
THROMBOTIC OCCLUSION
Thrombotic occlusion in lower limbs
> 80%
Thrombotic occlusion in upper limbs
half due to thrombosis
one third due to embolism
Other than plaque rupture, progression of ischemic injury can occur by:
(1) propagation of clot to occlude collateral vessels,
(2) ischemia related distal edema leading to high compartment pressures (compartment syndrome),
(3) fragmentation of clot into the microcirculation, and
(4) edema of the microvasculature cells.
Occlusion from embolism is MORE common than occlusion from thrombosis
FALSE
less common
The __________ is the predominant source of peripheral emboli, with ___________________ being responsible for most cases.
heart; atrial fibrillation
Noncardiac sources of arterial emboli
thrombi from aneurysms
atheromatous plaques
Most common location where emboli lodges
1) Bifurcation of the common femoral artery
2) Popliteal artery
An embolus may fragment and embolize distally, or it may propagate locally and create a larger clot.
Most commonly affected of embolism in the upper limb
Brachial artery
Patients with acute limb ischemia exhibit one or more of the “six Ps”
pain
pallor
paralysis
pulselessness
paresthesias
poikilothermia (for cold)
A lack of one or more of the 6Ps findings does not exclude ischemia
TRUE
__________ alone may be the earliest symptom of ischemia, localized in the limb distal to the site of obstruction.
PAIN
Skin changes
Pallor –> blotchy and mottled areas of cyanosis –> petechiae and blisters –> skin and fat necrosis (late)
Painful cyanotic discoloration of isolated portion of foot; remainder of the foot is warm
Trash foot or blue toe syndrome
Vasospasm in small arteries or arterioles provoked by cold or stressors;
Local pain, pallor, cyanosis, numbness, paresthesias in hands usually resolving in 30–60 min;
Rewarming, medications: calcium channel blockers, α-blockers, vasodilators
Raynaud’s disease
Young Asian women: peripheral ischemia and necrosis leading to pulseless phase; may have fever, rash, muscle aches, arthritis
Takayasu’s arteritis
Painful nodules, ulceration, and gangrenous digits in young adults (age 20–40 y);
Nonatherosclerotic segmental inflammation of small/medium vessels; typically, seen only in smokers
Thromboangiitis obliterans (Buerger’s disease)
Painful discoloration of one or more ulnar fingers with sparing of thumb;
Repeated trauma to the hypothenar area with hammering in laborers, as well as those using vibrational tools, causing narrowing of ulnar artery or aneurysmal degeneration
Hypothenar hammer syndrome
Thigh pain and numbness in cyclists and triathletes: measure pre- and postcycling ankle-brachial indexes
External iliac artery endofibrosis
Criteria use of Acute limb ischemia
Rutherford Criteria
Acute limb ischemia
symptoms starting within a 2-week
period
Pain over the distal forefoot waking the patient at night or requiring the patient to hang his or her feet over the bed
Seen in chronic peripheral arterial disease
Claudication
cramp-like pain, ache, or tiredness that is brought on by exercise and relieved by rest, similarly to angina in the heart;
reproducible, resolves within 2 to 5 minutes of rest, and recurs at consistent walking distances
Claudication
Claudication site: Buttocks, thigh, and sometimes calf (if bilateral, may cause impotence in men)
Iliac artery
Claudication site: Thigh
Common Femoral Artery
Claudication site: Upper two-thirds of calf
Superficial femoral artery
Claudication site: Lower one third of calf
Popliteal artery
Claudication site: Foot
Infrapopliteal (tibial and peroneal) artery
Hallmarks of chronic peripheral arterial disease
Shiny, hyperpigmented skin with hair loss and ulceration, muscle atrophy, and poor pulses
Ratio of the systolic blood pressure with the cuff just above the malleolus (with the Doppler probe over the posterior tibial or dorsalis pedis artery) to the highest brachial pressure in either arm
ankle-brachial index
ABI interpretation
Chronic <0.9
Severe <0.4
Noncompressible vessel >1.3
initial therapy of choice in the ED
IV unfractionated heparin (weight-based 80 units/kg bolus followed by an infusion of 18 units/kg/h)
80-18
