Adult-Gerontology Acute Care Practice Guidelines
Definition
A.Acute limb ischemia (ALI) is a sudden decrease in limb perfusion that causes a potential threat to limb viability.
Incidence
A.The incidence of ALI is approximately 1.5 cases per 10,000 persons per year.
Pathogenesis
A.Arterial emboli that travel to the extremities predominantly originate from the heart.
B.Paradoxical emboli occur when venous thrombus traverse a cardiac defect and lodge in the arterial circulation.
C.Arterial thrombosis can occur where there is an atherosclerotic plaque or arterial aneurysm at sites of prior revascularization or in patients with thrombophilic conditions.
D.Arterial trauma can occur with interventional catheterization procedures, as well as blunt or penetrating injuries.
Predisposing Factors
A.Atrial fibrillation.
B.Recent myocardial infarction.
C.Aortic atherosclerosis.
D.Large vessel aneurysmal disease (e.g., aortic aneurysm, popliteal aneurysm).
E.Prior lower extremity revascularization (angioplasty/stent, bypass graft).
F.Risk factors for aortic dissection.
G.Arterial trauma.
H.Deep vein thrombosis (paradoxical embolism).
Subjective Data
A.Common complaints/symptoms.
1.The Six P’s
is the classic presentation of ALI in patients without underlying occlusive vascular disease.
a.Paresthesia.
b.Pain.
c.Pallor.
d.Pulselessness.
e.Poikilothermia (cold).
f.Paralysis.
2.The sudden and dramatic development of ischemic symptoms in a previously asymptomatic patient is most consistent with an embolus.
B.Common/typical scenario.
1.Other signs and symptoms.
a.Patients with known peripheral artery disease or those who have undergone prior revascularization may develop symptoms slower (hours to days), depending if collateral channels provide flow around the occlusion.
b.Upper limb ischemia is seldom limb threatening. Patients often present with a cold feeling and numbness, rather than pain in the arm. Duplex ultrasonography can confirm diagnosis. The arm often improves with anticoagulation. There should be a low threshold to undertake embolectomy if there is doubt about limb viability.
c.Blue toe syndrome is typically due to embolic occlusion of digital arteries with atherothrombotic material from proximal arterial sources. There is often a strong pedal pulse and a warm foot. Identification and eradication of the embolic source should be undertaken.
C.Family and social history.
1.Elicit onset, duration, and intensity of the Six P’s
of ALI (paresthesia, pain, pallor, pulselessness, poikilothermia, and paralysis).
2.Question the patient about previous peripheral artery disease, prior lower extremity revascularization, and aortic or popliteal aneurysm.
3.Question the patient about atrial fibrillation, coronary artery disease, recent myocardial infarction, valve disease, and deep vein thrombosis.
4.Inquire into the patient’s history of limb trauma.
5.Ask the patient about any condition that is a contraindication for administering pharmacological thrombolytic agents.
D.Review of systems.
1.Musculoskeletal: Ask about the following.
a.Temperature and pain of extremity.
b.Any numbness, tingling, or weakness.
Physical Examination
A.Check temperature, pulse, respirations, and oxygen saturation.
B.Take blood pressure on both arms.
C.Inspect: Observe affected limb and compare with contralateral limb for mottling, pale, rubra, or necrosis.
D.Auscultate.
1.Heart and lungs.
2.Carotid, abdominal aorta pulses.
3.Pulse of affected limb with the contralateral limb.
a.Arm: Brachial.
b.Leg: Femoral, popliteal.
E.Palpate.
1.Palpate and compare the pulses of the affected limb with the contralateral limb.
a.Arm: Brachial, radial, ulnar pulses.
b.Leg: Femoral, popliteal, dorsalis pedis, post tibial pulses.
2.Check capillary refill of affected limb and compare with contralateral limb.
3.Check limb strength and movement of affected limb and compare with contralateral limb.
4.Check limb sensation of affected limb and compare with contralateral limb.
F.Handheld Doppler.
1.Assess pulses of affected limb with the contralateral limb and note if the pulse is monophasic, biphasic, or triphasic.
a.Arm: Brachial, radial, ulnar pulses.
Diagnostic Tests
A.12-Lead ECG to assess for underlying atrial fibrillation or myocardial infarction.
B.If distal leg pulses detected on handheld Doppler, obtain an ankle–brachial index (ABI). An ABI of about 0.3 is diagnostic of subcritical acute ischemia (refer to lower extremity peripheral artery disease for measuring ABI).
C.Full serum chemistry panel, including urea, creatinine, complete blood count, and baseline coagulation studies.
D.Vascular imaging.
1.The availability of specific imaging modality and the time required to perform and interpret the study should be weighed against the urgency for revascularization.
2.Patients should be anticoagulated prior to and during imaging.
3.CT is the investigation of choice.
4.Percutaneous angiography is the best choice when an endovascular solution to the arterial occlusion is likely.
Differential Diagnosis
A.Chronic critical limb ischemia.
B.Acute extremity compartment syndrome.
C.Extensive deep vein thrombosis.
D.Raynaud phenomenon.
E.Nonischemic limb pain from acute gout, neuropathy, spontaneous hemorrhage, or traumatic soft tissue injury.
Evaluation and Management Plan
A.General plan.
1.Systemic anticoagulation with unfractionated heparin.
a.Anticoagulation minimizes the risk of further clot propagation and prevents microvascular thrombosis of underperfused distal vessels.
2.Supportive measures.
a.Keep NPO by mouth until a definitive treatment plan has been determined.
b.Intravenous hydration, supplemental oxygen, and analgesia.
c.Results of vital signs, EKG, and serum panel will guide further therapy.
3.Treatment selection.
a.ALI treatment depends on the extent of limb ischemia (refer to Table 11.1).
b.Class I: ALI may require medical therapy only. Revascularization if contemplated can be performed electively.
c.Class II: ALI may require revascularization to preserve the affected extremity.
i.Class IIa: Percutaneous endovascular options are more effective in patients with ischemia of less than 2 weeks duration. Surgical revascularization is more effective in patients with ischemia of more than 2 weeks.
ii.Class IIb: Requires emergency revascularization. Treatment options will depend on timeliness, personnel, and resource availability.
d.Class III ALI. Revascularization is usually futile, and primary amputation should be considered.
4.Endovascular treatment options.
a.Catheter-directed thrombolysis.
b.Pharmacomechanical thrombectomy.
c.Catheter-directed thrombus aspiration.
d.Percutaneous mechanical thrombectomy.
5.Surgical revascularization options.
a.Balloon catheter thrombectomy or embolectomy.
b.Bypass procedures.
c.Endarterectomy.
d.Hybrid procedures combining open and endovascular techniques.
B.Pharmacological.
1.There are no pharmacological treatment options for ALI.
2.This is a surgical emergency.
3.Systemic anticoagulation with a heparin drip may be started to minimize further clot propagation and to prevent microvascular thrombosis.
4.Administer an initial bolus of 100 mg/kg followed by an intravenous infusion of 1,000 U/hr.
5.If an urgent operation is not undertaken, the heparin should be titrated to maintain an activated partial thromboplastin (aPTT) between 60 and 100 seconds.
6.Postoperatively, patients will need to be started on long-term oral anticoagulation.
C.Discharge.
1.Patients will need to be maintained on anticoagulation after surgery and will need to follow-up with vascular surgery for the surgical wound. Patients need to be taught about side effects of anticoagulation therapy and signs and symptoms of effective wound healing.
Follow-Up
A.Outpatient vascular specialty after 4 to 6 weeks.
B.Outpatient cardiology (if emboli likely to have originated from the heart) after 4 to 6 weeks.
Consultation/Referral
A.ALI is an emergency.
B.Immediate transfer to hospital for urgent vascular consult.
Special/Geriatric Considerations
A.Patients with ALI are usually elderly.
Bibliography
Cronenwett, J. L., & Johnston, K. W. (2014). Rutherford’s vascular surgery (8th ed). Philadelphia, PA: Elsevier Saunders.
Gerhard-Herman, M. D., Gornick, H. L., Barrett, C., Barshes, N. R., Corriere, M. A., Drachman, D. E., … Walsh, M. E. (2016). 2016 AHA/ACC guideline on the management of patients with lower extremity peripheral artery disease: A report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Journal of the American College of Cardiology, 69, 1465–1508. doi:10.1016/j.jacc.2016.11.008
