Inadequate perfusion to the extremities

I. Problem/Condition.

Inadequate perfusion to the extremities refers to decreased arterial blood flow to the extremities. This can be due to a sudden embolic event obstructing arterial flow, or a chronic obstructive process leading to decreased arterial flow to the extremities.

II. Diagnostic Approach.

A. What is the differential diagnosis for this problem?

A useful method to formulate the differential diagnosis for inadequate perfusion to the extremities is to categorize by onset of symptoms. This section is organized by major disease processes followed by the etiologies of inadequate perfusion to the extremities that fall under each category.

Acute onset

Embolic events:

• Septic emboli

• Plaque rupture with distal embolization

• Blue toe syndrome

• Cholesterol emboli syndrome

• Thromboembolic events: hyperhomocysteinemia, antiphospholipid antibody syndrome, atrial fibrillation

Systemic events:

• Distributive shock

• Cardiogenic shock

• Endocarditis

Trauma:

• Compartment syndrome

Iatrogenic events:

• Cardiac catheterization

• Surgical ligation/laceration

Insidious onset

• Peripheral arterial disease

• Athrosclerotic thrombosis - mechanisms include:

  • Progressive atherosclerotic narrowing of an artery, with resulting low flow, stasis, and eventual thrombosis

  • Intraplaque hemorrhage and local hypercoagulability

• Vasculitis

• Abdominal aortic aneurysm

• Thoracic aortic dissection

• Carotid artery disease

• Venous stasis

  • Common iliac compression syndrome

• Mycotic aneurysm- infected aneurysm caused by fungi

• Local mass effect

  • Soft tissue masses - e.g., sarcoma

B. Describe a diagnostic approach/method to the patient with this problem.

Many times the diagnosis can be made through a careful history and physical and confirmed with a minimum number of tests. In this Chapter, we will focus on obtaining an accurate history and performing correct physical exam maneuvers to guide appropriate testing and achieve the diagnosis.

1. Historical information important in the diagnosis of this problem.

The most important initial question to ask the patient is the timing of the onset of the symptoms.

Time of onset

Acute limb ischemia - a sudden decrease in limb perfusion that causes a potential threat to limb viability manifested by ischemic rest pain, ischemic ulcers, and/or gangrene, in patients who present within 2 weeks of an acute event.

Critical limb ischemia is the same condition, except this term is reserved for patients who present greater than 2 weeks after an event, and is by definition, chronic.

If the patient had sudden onset of symptoms and presents acutely, he or she is likely to need urgent intervention, as there has not been sufficient time for development of collateral vessel.

Ascertain the timing, location and quality of symptoms

• While walking and relieved by rest (intermittent claudication)

• Rest pain in legs

• Location of pain:

  • Buttocks, thighs, calf, foot, arms

  • Chest or back

  • Neck, jaw or upper back

  • Pulsatile feeling in the abdomen

  • Sudden onset of lower back pain or abdominal pain

  • Coughing, hoarseness or trouble breathing

Obtain a complete past medical history

Obtaining a complete past medical history is always prudent, there are comorbidities of special significance. These include:

• Diabetes

• Hypertension

• Hyperlipidemia

• Smoking

• Advanced age

• Obesity

• Mixed connective tissue diseases

• Vasculitis

• Syphillis

• Tuberculosis

• Immunocompromised state

Comorbidities

If the patient is presenting with symptoms suggestive of inadequate perfusion to the arms, comorbidities of special significance include:

Buerger's disease (thrombangiitis obliterans)

Takayasu's disease

Raynaud's

Systemic lupus erythematosis

Rheumatoid arthritis

Scleroderma

Radiation therapy for breast cancer

2. Physical Examination maneuvers that are likely to be useful in diagnosing the cause of this problem.

Inspection should include assessing for:

Pallor upon raising the leg

Discoloration of distal extremities

Atrophic skin

Impaired nail growth

Ulcerations - usually over bony prominences/areas of trauma

Gangrene

Palpation should assess for:

Tenderness of the affected extremity

Pulselessness (Indicate exactly where to look for pulses):

• Absent dorsalis pedis OR absent posterior tibialis pulses is not uncommon, however, the absence of BOTH is extremely suggestive of arterial disease.

• Palpate the femoral, popliteal, and dorsalis pedis and posterior tibialis pulses in both legs

• Palpate the brachial (either in the antecubital fossa or in between the biceps and triceps muscles more proximally in the medial arm), ulnar and radial pulses.

• Expansile femoral pulsation (dilated arterial pulsation where the walls expand laterally with each beat) is diagnostic for false aneurysm formation after femoral artery puncture during cardiac catheterization.

Pulsatile mass in the abdomen

Palpate skin temperature compared to opposite extremity at the same level (i.e. foot to foot, not foot to calf)

Auscultation for bruits:

Iliac bruits are audible above the inguinal crease

Femoral bruits are audible in the thigh:

• A femoral bruit audible during systole and diastole is diagnostic for arteriovenous fistula (after femoral artery puncture in cardiac catheterization), Popliteal bruits (behind the knee)

Whenever possible listen for femoral bruits and palpate the pulses in both legs prior to cardiac catheterization so as to establish a baseline for the patient.

Complete occlusion of the vessel makes the bruit disappear

Other physical exam maneuvers:

Neurological exam can assess strength and sensation bilaterally.

Venous Filling Time:

• Find a prominent vein on the foot. Raise the leg above the table at 45 degrees for 1 minute. The patient then sits up and dangles his leg over the side of the table, and the physician times how long it takes for the vein to rise above the level of the skin. Times of greater than 20 seconds are considered abnormal.

Measurement of the Ankle Brachial Index (ABI):

• The ratio of the blood pressure at the ankle and the arm (<0.9 is indicative of lower extremity arterial disease)

• Measurement of the blood pressure segmentally along arms

Physical exam findings that are not as useful:

Capillary refill time, hairless extremities are not as helpful diagnostically.

3. Laboratory, radiographic and other tests that are likely to be useful in diagnosing the cause of this problem.

Laboratory studies:

• Lipid panel

• Homocysteine

• Lupus anticoagulant

• Blood cultures including fungal cultures

Imaging studies of affected extremities:

• Arterial duplex ultrasound

• Magnetic resonance angiography (MRA)

• Computed tomography (CT)

• Angiography

• Arteriography

• Abdominal ultrasound

• CT abdomen

• Magnetic resonance imaging (MRI) in abdomen

• Echocardiography

Electrocardiogram (ECG)

If upper extremities involved:

• Chest and neck X-rays

C. Criteria for Diagnosing Each Diagnosis in the Method Above.

When symptoms aresudden in onset the criteria for diagnosing embolic events involves pulseless and pallor of the affected extremity, end organ ischemia occurs, embolic events are most likely. If the vessel occluded is large enough, the occlusion can be seen on MRA or CT angiogram both of which are more commonly done than arteriography.

• Septic emboli (+ blood cultures/ +/- vegetation on left sided heart valves)

• Plaque rupture with distal embolization (elevated cholesterol, smoking history, recent instrumentation of femoral artery for cardiac catheterization)

• Blue toe syndrome (toe turns suddenly blue and ischemic from sudden occlusion of an end artery)

• Cholesterol emboli syndrome

• Thromboembolic events (these are the two most common etiologies for arterial thromboembolic events)

• Hyperhomocysteinemia (elevated homocysteine levels)

• Antiphospholipid antibody syndrome (+ Lupus Anticoagulant found twice over a time period)

• Atrial fibrillation with irregular rhythm on auscultation of the heart and afib seen on ECG

Compartment syndrome will have extremity swelling and antecedent trauma on history.

Embolization of plaque or closure device after cardiac catheterization will involve the same criteria as above for diagnosing embolic events, with the cardiac catheterization preceding the onset of symptoms.

Ligation or laceration of an artery will have ischemia (if ligation) or swelling (if bleeding occurring from laceration), and antecedent surgical intervention.

The criteria used to diagnoseinadequate perfusion to the extremities with an insidious onset differ somewhat from the criteria used to for acute onset etiologies because of the chronic effects to the extremity. The criteria for each of the diagnoses varies somewhat, and so will be explored individually for each diagnosis.

Peripheral arterial disease

History:

• Patient's symptoms will progress over a chronic course

• Pain occurs while walking and relieved by rest- termed intermittent claudication

• Rest Pain in legs occurs with progression of disease, and patients may even need to dangle the foot over the side of the bed to sleep

• Location of pain can help guide the level of the lesion:

  • ◦Buttocks, thighs, calf (signifies aortoiliac disease)

  • ◦Calf (indicates femoropopliteal disease)

  • ◦No pain or foot pain (peroneotibial disease)

  • ◦Arms can be involved as well: Arm claudication can be triggered by combing hair, washing hair, or lifting arms (do not confuse with hypothyroidism and PMR); Arm claudication can be associated with arm heaviness, weakness, or cramping

Exam:

• Atrophic skin, impaired nail growth, diminished pulses, pallor upon raising the leg, a dusky redness on dependency, ulcerations over bony prominences/areas of trauma.

• Severe cases can progress to gangrene of the distal extremity which can spread proximally.

• Tender, cool extremity

• Patients will have a prolonged venous filling time and a decreased ABI.

• In the arms, blood pressure will decrease as you progress distally taking segmental blood pressures.

Laboratory studies/imaging:

• Elevated cholesterol may be present

• An arterial duplex will show diminished blood flow to the affected area and will show collateral blood vessels, if present, and is a preferable exam to CTA or MRA from a time and cost effectiveness perspective.

Relevant comorbidities:

• Hypertension

• Diabetes

• Hyperlipidemia

• Smoking

• Advanced Age

• Obesity

Arterial thrombosis

Has the same diagnostic criteria as above, except the imaging studies will show a completely occluded vessel once thrombosis occurs. This often occurs without the patient realizing the timing of the actual thrombosis because collateral vessels have formed over time.

Abdominal aortic aneurysm

History:

• Presence of a pulsatile feeling in the abdomen can key the physician to the presence of an abdominal aortic aneurysm (AAA).

• Sudden onset of lower back or abdominal pain can signify an impending rupture of a AAA.

Exam:

• Pulsatile mass in abdomen

Imaging:

• Abdominal ultrasound is preferred for time savings and cost effectiveness, MRI and CT abdomen are also diagnostic test.

Relevant comorbidities (most relevant):

• Smoking

• Advanced age

Thoracic aortic aneurysm

History:

• Chest, upper back, neck and/or jaw pain

• Coughing, hoarseness or trouble breathing

Exam:

• There are no specific exam findings to help diagnose thoracic aortic aneurysm

Imaging:

• Echo, cardiac MRI

Relevant comorbidities

• Hypertension

• Vasculitis

• Mixed connective tissue diseases

• Syphillis

• Tuberculosis

Mycotic aneurysm

Depending on the location, will have similar presentations as aneurysms described above with a painful, pulsatile mass in the setting of systemic infection. It occurs due to impaction of a septic embolus and usually complicates bacterial endocarditis. Despite the name, they are generally caused by bacterial infections.

Local mass effect from soft tissue massess (i.e. sarcoma)

History and physical will be similar to other diagnoses with insidious onset, but imaging will reveal the mass and external arterial compression with otherwise patent vessels.

D. Over-utilized or “wasted” diagnostic tests associated with the evaluation of this problem.

Too often, a simple ultrasound or arterial duplex study will suffice, and imaging is obtained with CT and MRI with the risks of contrast administration.

III. Management while the Diagnostic Process is Proceeding.

A. Management of Clinical Problem Inadequate Perfusion To The Extremities .

Acute onset of symptoms and pulselessness require urgent consultation by a vascular surgeon.

If acute or critical limb ischemia is present, heparin administration (weight based bolus followed by weight based hourly rate) is indicated with a goal PTT between 60-80.

For large AAA or TAA, surgical consultation is also required - these topics are more fully discussed.

Otherwise, management of risk factors such as cholesterol, hypertension, diabetes, obesity is indicated.

B. Common Pitfalls and Side-Effects of Management of this Clinical Problem.

The most common pitfall is the lack of recognition of true pulselessness in a timely manner. If a pulse cannot be palpated, it should be heard with a bedside doppler machine. Oftentimes the examiner mistakes his own pulse for that of the patient's. To avoid this common mistake, count the pulse you feel and compare it to your own pulse (the carotid pulse is convenient for this) as they should almost always be different.

Aside from heparin administration as a temporizing measure, surgical intervention is the mainstay of treatment. Medications are rarely effective in the long term. Modification of risk factors can prevent progression of disease.