Acute limb ischaemiaBMJ 2000; 320 doi: http://dx.doi.org/10.1136/bmj.320.7237.764 (Published 18 March 2000) Cite this as: BMJ 2000;320:764
- Ken Callum,
- Andrew Bradbury
Limb ischaemia is classified on the basis of onset and severity. Complete acute ischaemia will lead to extensive tissue necrosis within six hours unless the limb is surgicallyrevascularised. Incomplete acute ischaemia can usually be treated medically in the first instance. Patients with irreversible ischaemia require urgent amputation unless it is tooextensive or the patient too ill to survive.
Apart from paralysis (inability to wiggle toes or fingers) and anaesthesia (loss of light touch over the dorsum of the foot or hand), the symptoms and signs of acute ischaemia are non-specific or inconsistently related to its completeness. Pain on squeezing the calf indicates muscle infarction and impending irreversible ischaemia.
Acute arterial occlusion is associated with intense spasm in the distal arterial tree, and initially the limb will appear “marble” white. Over the next few hours, the spasm relaxes and the skin fills with deoxygenated blood leading to mottling that is light blue or purple, has a fine reticular pattern, and blanches on pressure. At this stage the limb is still salvageable. However, as ischaemia progresses, stagnant blood coagulates leading to mottling that is darker in colour, coarser in pattern, and does not blanch. Finally, large patches of fixed staining progress to blistering and liquefaction. Attempts to revascularise such a limb are futile and will lead to life threatening reperfusion injury. In cases of real doubt the muscle can be examined at surgery through a small fasciotomy incision. It is usually obvious when the muscle is dead.
Acute limb ischaemia is most commonly caused by acute thrombotic occlusion of a pre-existing stenotic arterial segment (60% of cases) or by embolus …
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