Claudication, Critical limb ischaemia and Acute limb ischaemia Flashcards
What’s the main disease processes in peripheral arterial disease?
- Chronic limb ischaemia
- Critical limb ischaemia
- Acute limb ischaemia
What’s the typical natural history of peripheral arterial disease?
- Intermittent claudication
- Rest pain
- Non healing leg ulcer/gangrene
- Amputation
What is intermittent claudication?
Most often refers to cramping pains in the buttock or leg muscles, especially the calves which occurs after walking for a given distance or walking uphill. The pain is relieved by rest
Pain is almost always in the calf, whatever level of obstruction, but may extend into the thigh
What would calf claudication indicate in terms of disease site?
Femoral disease
What would buttock claudication indicate in terms of disease site?
Iliac disease
What are the risk factors for peripheral vascular disease?
Major (GASD)
- Gender - Male
- Aging
- Smoking
- Diabetes mellitus
Other
- Hypercholesterolaemia
- Hypertension
- Obesity
What is peripheral vascular disease?
Occurs due to atherosclerosis causing stenosis or arteries via a multifactorial process involving modifiable and non-modifiable risk factors
What are the most commonly affected vessels in PVD?
Those of the lower limbs
What is the pathophysiology of claudication?
Decreased blood flow to peripheral tissue leads to tissue ischaemia. These leads to a variety of outcomes, one of which is the release of adenosine, leads to the perception of pain
What would thigh claudication indicate in terms of disease location?
Iliac or Common femoral artery
What would pain in the lower 1/3rd of the calf indicate in terms of disease location?
Popliteal artery
What would claudication in the foot indicate in terms of disease location?
Tibial or peroneal artery
What are the signs/symptoms of peripheral vascular disease?
- Intermittent claudication
- Ulceration
- Skin colour changes - elevated pallor, dependant rubor
What is regarded as stage one PVD as per the Fontane classification system?
Asymptomatic disease
What is stage 2 peripheral vascular disease as per the Fontane classification system?
Intermittent claudication
What are the characteristics of stage 3 PVD as per the Fontane classification system?
Rest pain/nocturnal pain
What are the characteristics of stage 4 PVD as per the Fontane classification system?
Necrosis/gangrene
What physical signs are associated with someone suffering from intermittent claudication?
Absent/reduced pulses - dorsalis pedis, posterior tibial and popliteal inevitably absent
Trophic changes at this stage are rare, although there may be more systemic signs of vascular disease
What is Buerger’s sign?
In patients with suspected vascular disease, when the patient lies on their back with a leg elevated for at least a few minutes, the foot becomes white; the patient is then quickly sat upright with legs hanging down and the limb turns dark red.
What is the mechanism behind buergers sign?
Partial or total occlusion of the arteries of the leg by emboli or thrombosis leads to limited vascular flow to the distal leg and foot.
Raising the leg further worsens arterial blood flow to the limb, causing the foot to become white. When the foot is then placed close to the ground, gravity assists flow to the distal limb and, along with compensatory peripheral vasodilatation (in response to poor perfusion), the leg quickly turns red.
What does a positive buerger’s sign indicate?
A positive Buerger’s sign (loss of pallor and spreading redness on dependency) indicates severe limb-threatening ischaemia and should be treated immediately.
What is the definition of critical limb ischaemia?
Persistently recurring rest pain requiring regular analgesia for > 2 weeks, or ulceration or gangrene affecting the foot, plus an ankle systolic pressure of <50 mmHg
What is ABPI?
Ankle-Brachial Pressure Index
The ratio of the blood pressure at the ankle to the blood pressure in the upper arm (brachium). Compared to the arm, lower blood pressure in the leg is an indication of blocked arteries due to peripheral artery disease (PAD). The ABPI is calculated by dividing the systolic blood pressure at the ankle by the systolic blood pressure in the arm
What would an ABPI of > 1.2 indicate?
Calcified arteries
What would a normal ABPI score be?
0.9-1.2
What ABPI score would indicate intermittent claudication?
0.5-0.9
What would an ABPI of <0.5 indicate?
Critical limb ischaemia
What happens to ABPI readings when arteries are calcified?
Falsely increased
How would you investigate someone with suspected PVD?
- Bloods - glucose, ESR/CRP, FBC, U+Es, Lipid profile, thrombophilia screen
- ECG
- ABPI
- Pulses
-
Imaging
- Colour Duplex USS - 1st line
- DSA scan - if considering intervention
How would you examine someone for peripheral vascular disease?
- General examination - inpect, palpate, auscultate
- Vascular examination of the limbs - inspect, palpate, auscultate
- Buerger’s Test
What is a duplex scan?
https://www.youtube.com/watch?v=toIxc3MqYPQ
A form of medical ultrasonography that incorporates two elements:
- Grayscale ultrasound to visualize the structure or architecture of the body part. No motion or blood flow is assessed. This is the way plaque is directly imaged in an artery
- Color-Doppler ultrasound to visualize the flow or movement of a structure, typically used to image blood within an artery. Blood flow velocities increase through a region of narrowing, like a finger pressing up against the end of a running garden hose.
What is the definition of acute limb ischaemia?
Inadequate arterial blood supply to a limb over hours or days
What is the pathophysiological process behind acute limb ischaemia?
- Embolism - thrombus in the heart or other proximal site as point of origin
- Thormbosis - atherosclerotic plaque, aneurysm, aortic dissection
What is the name given to PVD that involves erectile function?
Leriche syndrome
How would a patient describe ischaemic rest pain?
Usually felt in the skin of the foot
Very severe and burning
When does rest pain most commonly occur?
At night/when feet are elevated - characteristically relieved by dangling legs over the side of the bed
What is implied by the term critical limb ischaemia?
Loss of part of the limb is inevitable unless it is revascularised
What is important to remember in someone who has PVD and diabetes, and who has progressed to a critically ischaemic stage?
May be painless, therefore may go unnoticed
Why might someone with diabetes and a severly ischaemic foot have warm and red skin?
Autonomic dysregulation of small vessels due to diabetic degeneration
What are the 6 P’s of acute limb ischaemia?
- Pain
- Pallor
- Paraesthesiae
- Paralysis
- Perishing cold
- Pulseless
When inspecting a limb for vascular disease, what would you look for?
- Dressings
- Ulceration - even between toes and the heels
- Colour change
- Scars
- Trophic changes
What are trophic changes of the limb?
Nutritional changes
- Hair loss
- Shiny skin/thickened
- Tissue loss
- Gangrene
- Ulceration
When palpating a limb for peripheral vascular disease, what should you look for?
- Skin temperature
- Capillary refill
- Peripheral pulses
- Neurological examination
When auscultating a limb for peripheral vascular disease, what should you listen for?
Bruits
What would white skin in an affected limb suggest?
- Physiological or vasospastic disorder
- Chronic ischaemia
- Acute ischaemia
- Constricted venules
What would blue or cyanotic skin on an affected limb suggest?
- Acute or chronic ischaemia
- DVT
What would reddening of the skin on a limb affected by PVD suggest?
- Cellulitis
- Chronic venous insufficiency
- “diabetic trap” - auatonomic dysregulation
- Severe ischaemia
In someone with claudication or rest pain, what does the onset of a dusky foot indicate?
Development of tissue necrosis
What are the different types of gangrene?
- Dry gangrene
- Wet gangrene
- Gas gangrene
What is dry gangrene?
A form of coagulative necrosis that develops in ischemic tissue, where the blood supply is inadequate to keep tissue viable. Dry gangrene is often due to peripheral artery disease, but can be due to acute limb ischemia.
What is wet gangrene?
Characterized by thriving bacteria and has a poor prognosis (compared to dry gangrene) due to sepsis resulting from the free communication between infected fluid and circulatory fluid.
In wet gangrene, the tissue is infected by saprogenic microorganisms (Clostridium perfringens or Bacillus fusiformis, for example), which cause tissue to swell and emit a fetid smell
What is gas gangrene?
Bacterial infection that produces gas within tissues. It can be caused by Clostridium, most commonly alpha toxin-producing C. perfringens, or various nonclostridial species.
Infection spreads rapidly as the gases produced by bacteria expand and infiltrate healthy tissue in the vicinity. Because of its ability to quickly spread to surrounding tissues, gas gangrene should be treated as a medical emergency.
What is the difference between wet and dry gangrene?
Wet gangrene is infected, whereas dry is not
What is a DSA scan?
Digital subtraction angiography -
Images are acquired by exposing an area of interest with time-controlled x-rays while injecting contrast medium into the blood vessels. The image obtained would also include all overlying structure besides the blood vessels in this area.
In order to remove these distracting structures to see the vessels better, the surrounding structures are removed by the radiographer so that they can view the image clearly
What risks do DSA scans carry?
- Arterial cannulation complications
- Reaction to contrast
When investigating for PVD, why would you look at blood glucose?
Assess for diabetes
When performing bloods for suspected PVD, why would you do U+E’s?
Assess for renal disease
When doing bloods when investigating for suspected PVD, why would you do an FBC?
Look for anaemia or polycythaemia
Why would you perform an ECG when investigating PVD?
Look for signs of cardiac ischaemia
Whe inspecting as part of the general vascular exam, what would you look for?
- Signs of cardiac failure - breathless, can’t lie flat, raised JVP
- Skin colour
When palpating as part of a general vascular examination, what would you palpate?
- Abdomen - AAA
- Pulses
- Ankles - oedema indicative of CF
When ausculating as part of the general vascular examination, what would you listen to?
- Heart sounds
- Arterial bruits - AA, carotids, subclavian, renal and femoral
- Lung bases
What are the phsyical signs of severe ischaemia of a limb?
- Trophic changes
- Patchy necrosis of toes/skin on the foot
- Positive buerger’s test
- Extreme vulnerability to pressure ulcers
How would you manage someone with intermittent claudication?
Lifestyle modification
- STOP SMOKING
- Supervised exercise programme
- Lose weight
Medications
- Statin
- Clopigorel - 1st line
- Aspirin - 2nd line
- Hypertension
- Diabetes
IF CONSERVATIVE FAILS
- Balloon angioplasty
How would you manage severe ischaemia of a limb?
- Lifestyle modification
-
Surgery
- Balloon angioplasty
- Reconstructive surgery - bypass graft
How would you manage someone with critical limb ischaemia?
- Lifestyle modification
-
Surgery
- Balloon angioplasty
- Reconstructive surgery
- Amputation
What is percuteneous transluminal angioplasty?
Balloon angioplasty
Involves cannulating an artery, introducing a guiding wire and advancing it to lie across the stenosis. A balloon catheter is passed over the wire and into position, where it is inflated to a high pressure, crushing the atheroma into the arterial wall to relieve the obstruction.
https://www.youtube.com/watch?v=W3b4J8jjQKY
What are the different types of arterial reconstructive surgery available for treating PVD?
- Femoro-popliteal bypass
- Femoral-femoral crossover graft
- Aorto-bifemoral bypass graft
What are the complications of arterial surgery?
- Stroke
- Acute myocardial ischaemia
- Intestinal ischaemia
- Haemorrhage
- Thrombosis of graft
- Embolism into limb
- Graft infection
- False aneurysm
Where can emboli arise from which can cause acute limb ischaemia?
- Heart - AF, Mitral stenosis, mural thrombus from MI
- Aneurysms - femoral, popliteal
What are thrombotic causes of acute limb ischaemia?
- Popliteal aneurysms
- Blood disorders - polycythaemia vera, thrombocytopenia, leukaemia
- Nephrotic syndrome
- HHS - diabetes
What is an acute-on chronic occlusion?
An essential distributing artery that was previously narrowed by atherosclerosis becomes obstructed by secondary thrombosis or by rupture of an atherosclerotic plaque
What are the risks of not treating an acutely ischaemic limb immediately?
- Muscle necrosis
- Reperfusion injury
- Compartment syndrome
What does fixed skin mottling indicate?
Irreversible necrotic damage - often accompanied by skin blistering
Limb loss is inevitable in this context
How would you manage someone with acute limb ischaemia and you had determined an embolus was the cause?
- IV heparin - 5000 units
- Analgesia
-
Determine if limb is salvagable
- IF YES - PCD thrombolysis or EMBOLECTOMY if in immediate danger
- IF NO - Amputation
How would you investigate someone with suspected acute limb ischaemia?
- ECG
- CXR
- Routine bloods
- Crossmatch
- Angiography - if you have time
How would you manage someone with an acutely ischaemic limb which you had determined a thrombus to be the cause of?
- IV heparin - 5000 units
- Analgesia
-
Angiograpy first, then determine limb viability
- IF YES - PCD Thrombolysis and PTA/Bypass, OR Bypass alone
- IF NO - Amputation
