1. Acute limb ischemia occurs due to a sudden decrease in blood flow to a limb, threatening the viability of the extremity. It requires prompt diagnosis and treatment to determine if the limb is viable, threatened, or irreversibly ischemic. 2. Initial management involves analgesia, oxygen, intravenous heparin, and urgent referral to a vascular specialist. Further imaging and either surgical or endovascular revascularization may be needed depending on the classification of ischemia. 3. The prognosis depends on factors like etiology and severity of ischemia. With timely treatment, limb salvage is possible in the majority of patients.

1. Acute Limb Ischemia
KHALID ALRAJHI, MD
Consultant of Vascular and Endovascular surgery
Lead of Vascular & Endovascular Surgery, Jazan
Province
Kingdom of Saudi Arabia

2. Acute Limb
Ischemia
• It occurs due to a sudden decrease in
the blood flow to a limb, resulting in a
potential threat to the viability of the
extremity.
• The incidence is estimated at
approximately 1 per 6000 population
per year.

3. • The spectrum of acute limb ischemia therefore
ranges from the patient with a few hours history of
a painful cold white leg, to the patient with a few
days history of short distance claudication or the
patient with a sudden increase in ischemic
symptoms on a background of peripheral arterial
disease.

4. Acute Limb Ischemia
Limb hypoperfusion results in systemic acid-base and electrolyte abnormalities
that impair cardiopulmonary and renal function.
Successful reperfusion may result in the release of highly toxic free radicals,
further compromising these critically ill patients.
the management of acute limb ischemia requires a thorough understanding of
the anatomy of the arterial occlusion and the open surgical and percutaneous
options for restoring limb perfusion.

5. • The presentation of acute on chronic limb ischaemia is
more common in an ageing population.
• The classical signs of acute limb ischaemia may be
attenuated by the presence of collaterals, diagnosis will
be difficult for non experts.
• Patients presenting primarily with embolic disease may
well also have underlying peripheral arterial disease,
which is present in up to 30% of people over the age of
70 years.
Prescott R. et al.
Regensteiner JG, C et
al.

6. Risk Factors
Age
Atrial fibrilation
Smoking
Diabetis Mellitus
Hypertension
Dyslipedemia
Pre-existing peripheral arterial disease
Abdominal or peripheral arterial aneurysm

7. Mortality and Morbidity
• is important to diagnose because it carries a high mortality and morbidity.
• Estimates of mortality following acute limb ischemia range from 9-22% , but
the timeframe of this mortality is important.
• 30-day survival with acute limb ischemia was 75.3% compared with critical
limb ischemia at 92.6%.
Trippestad A et al
Szymanska TH et al

8. • Limb salvage following acute limb ischemia is
estimated at 70-90%.
• Amputations are more common following
thrombotic occlusions, since these are more likely
to occur on a background of peripheral arterial
disease.
Cowan J, et al
Patel M, et al

9. Pathophysiology
• An embolus is defined as a material (gas, solid or liquid) that is carried within the
circulation and lodges in a blood vessel in another part of the circulation, causing
occlusion of the blood vessel.
• Radiologically the upper border of an embolus is classically concave, known as the
meniscus sign
• Emboli most commonly arise from heart (80%) and as such are usually composed of
platelets.
• In the Oxford study, 23.6% of events were cardioembolic; of this group 70.5% had
known atrial fibrillation diagnosed before the event.
• Emboli can also arise from proximal arterial disease (either aneurysms or stenoses)
and may then contain atheroma. These carry a poorer prognosis for the limb since they
are harder to treat and not amenable to thrombolysis.

10. 1. Phenomena of interrupted blood flow, eg stasis: risks include venous stasis, long surgical operations,
prolonged immobility, and varicose veins.
2. Phenomena associated with irritation of the vessel and its vicinity, eg endothelial or vessel wall injury:
includes injury or trauma such as vessel piercings, damage arising from shear stress or hypertension, and
subsequent contact with procoagulant surfaces, such as bacteria, shards of foreign materials, biomaterials
of implants or medical devices, membranes of activated platelets, and membranes of monocytes in chronic
inflammation.
1. Phenomena of blood coagulation, eg hypercoagulability: risk factors such as hyperviscosity, coagulation
factor V Leiden mutation, coagulation factor II G2021A mutation, deficiency of antithrombin III, protein C or
S deficiency, nephrotic syndrome, changes after severe trauma or burn, cancer, late pregnancy and
delivery, race, advanced age, cigarette smoking, hormonal contraceptives, and obesity.
Thrombosis may be influenced by any of the three factors described in Virchow's Triad

11. Rarer causes of acute limb ischemia

12. Clinical Assessment
The Classic presentation the 6Ps
• Pain In most cases this will occur at rest, although a patient with a viable limb
may present with acute onset short distance claudication. Rest pain is usually
worse in the most distal part of the limb (toes) since this has the worst perfusion,
may be relieved on dependency (hanging legs over bed). Pain which is worse on
passive movement of the muscles indicates potential compartment syndrome, is
a poor prognostic sign.
• Pallor in comparison to the opposite limb; it is also useful to check venous filling.
Acutely ischemic limbs are classically white rather than blue. Chronic critically
ischemic limbs may appear pink due to compensatory vasodilation the so-called
sunset foot . In this situation Buergers test may also be useful (pallor on elevation
of the limb, with erythema on dependency).

13. • Paresthesia this is present in over 50% cases. Sensory
nerves are smaller than motor nerves and more sensitive to
ischemia so tend to be affected first.
• Paralysis this is a poor prognostic sign and indicates an
element of irreversible ischemia.
• Perishingly cold this is a useful sign if used in comparison
to the opposite (normal ) limb.
• Pulselessness no pulses at peripheral arteries.
Arterial Doppler signals should be checked in anyone with suspected acute limb
ischemia.

14. Physical Examination
Cardiovascular
• cardiac arrhythmias or possible valvular heart disease as a source of emboli.
• The abdomen should be assessed for abdominal aortic aneurysm.
The affected leg
• Inspection
• Colour: Fixed mottling of the leg is a poor prognostic sign and implies irreversible
ischemia. Patients with classical emboli have a white leg (with a normal leg on the
opposite side); in patients with thrombotic occlusions the signs may be more subtle
since collaterals may have formed due to pre-existing peripheral arterial disease.
• Scars: Look for scars of previous surgery. Surgery on the abdominal aorta may be via a
midline or transverse incision, scars on the groin. behind the knee patients who have
had a popliteal aneurysm repair.

15. • Palpation
• Temperature: Always compare to the opposite leg.
• Pulses: It is particularly important to determine whether the patient has a palpable femoral
pulse.
• Tenderness: Is the limb tender? This again is a poor prognostic sign as it suggests muscle
ischaemia. Is there pain on passive movement? This suggests compartment syndrome and
requires immediate intervention.
• Neurological function: Test sensory and motor function. Loss of sensation is common.
Loss of motor function is a poor prognostic sign.
• Auscultation
• Arterial Doppler signals
The Other Leg
It is essential to fully examine both legs, the comparison between the normal and abnormal leg
will often aid both diagnosis and determining probable etiology.

16. Classification
• The purpose of the history and examination is to determine three things:
1.Is the leg acutely ischemic? (Or is there an alternative diagnosis?)
2.Is the likely cause embolic or thrombotic?
3.Is the leg viable, threatened or irreversibly ischemic?
• The answers to these three questions will determine the immediate management. It is not always possible to
distinguish between embolic and thrombotic etiology, since many patients with an embolic cause may also have
some underlying peripheral arterial disease.
• It is most important to decide whether the leg is viable, threatened or irreversibly ischemic

17. Rutherford's classification of acute limb ischemia
Sensorimotor deficit helps identify limbs in need of urgent intervention. Fixed staining and profound paralysis are signs of irreversible
ischemia

18. Differential Diagnosis
• Compartment Syndrome.
• Cerebrovascular accident (CVA): although the limb may be pale, cold and
paralyzed it should not be painful and Doppler signals should be audible.
• Deep vein thrombosis (DVT): the leg is usually warm, pink, swollen and tender. In
phlegmasia cerulea dolens a DVT can cause venous gangrene. The foot usually
appears blue, purple or black. Arterial Doppler signals should be audible.
Phlegmasia cerulean dolens should also be referred to a vascular specialist.
• Hypovolemic Shock can present with pulseless limbs, but an accurate history and
examination (hypotension, all limbs affected) should clarify the diagnosis
Arterial Doppler examination and an accurate history should differentiate acute limb ischemia from other
common differential diagnoses.

19. Investigation
• ECG: To diagnose atrial fibrillation or other cardiac arrhythmias or an acute
cardiac event, which may be a source of emboli.
• Bloods: Blood tests relevant to a suspected acutely ischemic limb as following :

20. Radiological Study
• The urgency of imaging depends on the presentation.
• Conventional imaging consists of a digital subtraction angiogram.
This is an invasive procedure using intra-arterial contrast but has
the potential for therapeutic intervention (thrombolysis,
angioplasty).
• MR angiography and CT angiography are less invasive and
should provide the same anatomical information. Arterial duplex
is non-invasive but is operator dependent and iliac and calf
vessels can be difficult to image.
• The choice of imaging is likely to depend on the local resources
available.

21. Management
Initial management in the Emergency Department
• Analgesia: NSAIDs may increase the risk of myocardial events and should not be used
routinely. Neuropathic pain may sometimes be associated with critical limb ischemia. As
with any painful condition there is no rationale to withhold analgesia in order to facilitate
assessment.
• Oxygen: all patients should be administered supplemental oxygen.
• Heparin: 5000 units intravenous heparin (unfractionated) should be given immediately to all
patients with acute limb ischemia, even they are likely to be undergoing surgery or
angiography. This is to prevent propagation of thrombosis. In patients in whom definitive
treatment is deferred an intravenous heparin infusion should be prescribed.
• IV Fluids: Patients with acute limb ischemia are often dehydrated. Also they are likely to be
undergoing surgery or being given iodinated contrast which will be a further renal insult.
Reperfusion of ischemic tissue releases toxic metabolites, potassium, creatinine kinase and
myoglobin which can further damage the kidneys. Administration of potassium should be
avoided.

22. • Refer to a vascular specialist urgently. Any delay
risks jeopardizing the limb, particularly if there is
sensorimotor impairment. Familiarity with local
vascular center policies is advisable; it is also
important to be familiar with medication limitations
for prehospital and transport services, who may
not be able to transport patients on heparin
infusions.
All patients with acute limb ischemia should receive analgesia,
oxygen and heparin.
All patients with acute limb ischemia should be referred urgently
to a vascular specialist.

23. Definitive management
based on Rutherford's Classification
• Category I These patients have a viable limb. They should be admitted, given analgesia and oxygen
and heparinized (infusion). There is no good evidence to support the use of low molecular weight
heparin in this situation and it is more difficult to adjust if interventions are required. Formal imaging
(angiogram, MR angiogram, CT angiogram or arterial duplex depending on local resources) should
then be arranged within normal working hours to plan definitive treatment.
• Category IIa These patients have a threatened limb. They should be given oxygen, analgesia and
heparin. they should have immediate imaging, in order to guide operative (or endovascular)
intervention. In some cases where there is minimal sensory loss only, they may be managed
conservatively overnight, and imaging obtained the following day.

24. • Category IIb These patients have a threatened limb and cannot wait overnight. They should be given
oxygen, analgesia and heparin. If circumstances allow it may be possible to obtain imaging prior to
theatre, but this should not delay intervention. They need urgent revascularization, either operatively or
with thrombolysis. In a patient with a clear history for embolus (and a source of embolus) and a normal
contralateral limb, an embolectomy may be performed under local anesthesia. The advantage of this is
that local anesthesia is better tolerated by elderly patients with cardiac comorbidity. The disadvantage
is that if a simple embolectomy is unsuccessful and a more extensive procedure is required it may be
necessary to convert to general anesthesia. In all cases an anesthetist should be present to manage
the patient medically during the procedure. On-table imaging should be available and the whole leg
prepared and draped.
• Following revascularization the limb may swell and the need for fasciotomy should always be
considered.

25. • Category III These patients have irreversible ischemia and the limb is not salvageable.
Revascularization in this situation is likely to kill the patient, due to the massive release of
potassium, creatine kinase, myoglobin, lactate and oxygen free radicals from the ischemic tissue
which can cause renal failure, myocardial toxicity and multi-organ failure. The options are either
amputation or palliation. In an acute scenario with evidence of infection a so-called guillotine
amputation may be performed in order to allow a quick operation to remove necrotic/infected tissue,
with a definitive amputation at a later date once the patient is more stable and infection has been
treated. It is vital to recognize those patients in which an ischemic limb is part of the process of
dying, and not subject them to unnecessary and futile interventions.

26. Thrombolysis
• Intra-arterial thrombolysis is an alternative treatment to surgery for the acutely
ischemic limb.
• Intra-arterial streptokinase or rtPA (tissue plasminogen activator) convert
plasminogen into plasmin, which lyses thrombin.
• Following thrombolysis an angiogram should be performed to identify any
underlying stenosis.
• There have been five randomized controlled trials comparing surgery with
thrombolysis in the acutely ischemic limb including 1283 patients, which have
been analyzed in a systematic review.
• Major complications were more common after thrombolysis risk of stroke and
and risk of major hemorrhage.

27. • Interventional radiology approaches, including
mechanical thrombectomy, have gained an
evidence base in treatment of acute CVA. In
patients presenting with ALI (<2 weeks of
duration), endovascular and surgical
approaches have similar rates of short-term
and 12 month mortality, limb amputation and
recurrent ischemia.
There is no evidence to favor thrombolysis over surgery in the acutely ischemic limb.
Patel M, et
al

28. Acute upper limb ischemia
• Acute arm ischemia is much less common than acute leg
ischemia (about 20% of all limb ischemia), and is usually due
to cardiac emboli since atherosclerosis does not usually
affect upper limb vessels.
• Vasculitis and thoracic outlet syndrome can rarely cause an
acutely ischemic arm.
• The commonest sites of occlusion are the axillary and
brachial arteries.
• The clinical assessment, if there is no neuromuscular
impairment patients can be admitted and heparinized
overnight. If signs of sensorimotor impairment should
proceed to surgery. This will usually consist of a brachial
embolectomy.
Earnshaw JJ et
al

29. • The initial management follows the same principles as for the
acutely ischemic leg: oxygen, analgesia and IV heparin. The
patient should then be referred to a vascular specialist.
• MRA demonstrating emboli to the left hand, causing loss of
the digital arteries to the lateral aspect of the index and middle
fingers and the medial aspect of the ring and little fingers. This
presented with cool pale 4th and 5th fingers.

30. Prognosis and Follow up
Popliteal aneurysms acute limb ischemia due to a thrombosed popliteal
aneurysm carries a 50% risk of amputation.
Palliative care Acute limb ischemia may occur as a pre-terminal event. It is
important to recognize this, in order that a patient who is dying may be
managed appropriately and spared futile interventions.
Bilateral limb ischemia can be more difficult to diagnose, since both legs
are abnormal. It may be caused by a saddle embolus at the aortic
bifurcation (which carries a high (30%) mortality. It can occur as a result of
abdominal aortic dissection (patient classically presents with back pain and
hypotension).