Table 7.

Interpreting ankle brachial pressure index

Index	Signs and symptoms	Severity of disease	Action
≥0.7-1	Mild intermittent claudication, or no symptoms	Mild arterial disease	Reduce risk factors and change lifestyle: stop smoking, maintain weight, exercise regularly, consider antiplatelet agent
0.7-0.5	Varying degrees of intermittent claudication	Mild to moderate arterial disease	As for index ≥0.7-1, plus referral to outpatient vascular specialist and possible arterial imaging (duplex scan and/or angiogram)
0.5-0.3	Severe intermittent claudication and rest pain	Severe arterial disease	As for index ≥0.7-1, plus urgent referral to vascular specialist and possible arterial imaging (duplex scan and/or angiogram)
≤ 0.3 or ankle systolic pressure <50 mm Hg	Critical ischaemia (rest pain >2 weeks) with or without tissue loss (ulcer, gangrene)	Severe arterial disease; risk of losing limb	Urgent referral to vascular emergency on-call team and possible surgical or radiological intervention

An index of 1 to 1.1 is considered to be normal. The data in the table should be used as an adjunct to the clinical findings. Erroneous readings may be the result of incompressible arteries secondary to presence of calcification or presence of tissue oedema. Patients may present with an arterial ulcer even with a normal index. Patients may present with an acutely ischaemic limb either due to an embolus or a thrombus (“acute on chronic” ischaemia) and should be referred as an emergency to a vascular specialist or emergency department for urgent intervention to prevent imminent limb loss.