Clinical part of the "Nerves/Vessels Review" Questions Flashcards
Where would you palpate the femoral artery pulse?
Mid-inguinal point
Where would you palpate the popliteal artery pulse?
Inferior part of the popliteal fossa, against the posterior surface of the tibia
Where would you palpate the posterior tibial artery pulse?
Behind the medial malleolus
Where would you palpate the dorsalis pedis artery pulse?
Dorsum of foot, lateral to extensor hallucis longus tendon
What are the likely causes and consequences of embolism in the lower limb?
Causes
- sudden occlusion of an atherosclerotic vessel or thrombus from atrial fibrillation
- suddenly occluded vessels represent potentially severe consequences
Consequences
- e.g. if an arterial clot forms in the popliteal artery, there may be no time for a collateral circulation to develop and the leg may become ischaemic and require amputation if the lesion is not cleared within a few hours
Explain the term “intermittent claudication” and its consequences.
A condition where there is gradual occlusion of the arteries within the limb, usually athersclerotic
- the muscles supplied distal to the occlusion become deprived of blood during exercise so there is limited walking distance before pain occurs, most commonly in the calf, but also can occur in the thigh/buttock.
What is compartment syndrome?
There are 3 compartments in the leg. Each compartment is bound by a very tight fascia which only lets the muscles inside the compartment expand to a certain degree. Past this point, the fascia starts exerting pressure within the muscle
- if the muscle swells too much, the arterial supply and venous drainage of the muscle gets cut off, resulting in muscle death and loss of movement within the limb.
What are the two types of compartment syndrome that can occur?
Acute - after trauma to a limb, requires urgent release of fascia by fasciotomy or the muscle will die with severe consequences
Chronic - occurs in athletes when the muscles swell during exercise
Arterial pulse is NOT lost in acute CS, pressure reached in the tissue is not high enough to prevent pulse from occurring
Explain the mechanism for venous return from the lower limb in terms of superficial and deep veins, perforating veins, valves and the muscle pump.
Valves in the veins allow flow only up towards the heart.
In the leg, the deep vessels are sandwiched between layers of calf muscles
During walking and running, contractions of these muscles squeeze the thin-walled veins and push blood up the veins = THE CALF PUMP
Sluggish deep venous return can lead to Deep Vein Thrombosis
What are the main feature of varicose veins and what are the symptoms/pathology of them?
The valves preventing back flow of blood at the sapheno-femoral junction are incompetent = causes back flow and varicose veins
- can be painful, causing an aching discomfort on standing
- varicose veins are dilated and tortuous superficial veins
Varicose veins can be pathological in that the increased pressure within the superficial venous system can caused increased pressure in the superficial circulation, causing skin changes (lipodermatosclerosis) and often skin ulcers.
Where can the femoral artery and vein be cannulated, why is this done?
Femoral artery and vein can be easily exposed and cannulated at the groin
- for cardiac arteriography (artery)
- for resuscitation (vein)
Describe how to perform a “cut-down” of the long saphenous vein at the ankle, including its anatomical landmarks and clinical importance.
In a shocked patient, venous cannulation may not be easy or possible.
The anatomical surface marking of the long saphenous vein at the ankle (2cm above and proximal to the tip of the medial malleolus) makes it an excellent site to perform a “cut-down”
- a small incision is made at the ankle and a venous cannula placed, under direct vision, into the vein for resuscitation.
How and why are superficial veins of the lower limb used as grafts in elective surgery?
The saphenous veins are often used in cardiac and vascular surgery as grafts to replace arteries,
- e.g. arterial by-pass surgery
The veins must be orientated correctly due to the valves present within them
- this is possible as there is such excellent anastomosis in the leg, the removal of the superficial veins rarely causes a problem.
What is a DVT, where can it present and what are the different types called?
Blood can clot (thrombose) in the superficial and deep veins of the lower limb. When it happens in the deep veins, this is termed deep venous thrombosis (DVT)
DVT is often ‘silent’ but may present with pain + swelling in the calf or proximal thigh
Distal DVT = in the calf
Proximal DVT = into the thigh/pelvis
Proximal is very dangerous because of a high risk of propagation into the lungs = pulmonary embolism.
Clinically, what can cause DVTs and what are the main consequences?
Clinically, DVT can be idiopathic, caused by immobility, trauma, surgery, obesity, malignancy, pregnancy or the use of the oral contraceptive pill.
There are two main consequences:
1) the clot may propagate into the pulmonary circulation, causing a pulmonary embolus (PE). A PE may be fatal and for this reason DVTs are usually treated with anticoagulation to prevent this.
2) the clot in the deep veins may cause increased back pressure in the deep veins, causing venous insufficiency and leg ulcers (the POST-PHLEBITIC SYNDROME)
