Editor—Marshall and Flyvbjerg's clinical review gives contradictory information about measuring the ankle-brachial pressure ratio in diabetic patients, as well as portraying an unrealistic picture of the assessment of peripheral arterial disease in them.1
Firstly, 10-15% of diabetic patients may have a falsely raised ankle-brachial pressure ratio because early calcification of the tunica media renders the arteries incompressible.2 This should not be solely relied on as an objective assessment criterion. The pole test is more accurate.3 The arteries of the foot and toes are comparatively spared in diabetes. Therefore other tests—such as the toe pressure index, analysis of Doppler wave form, pulse volume analysis, and transcutaneous oxygen measurements—are far better but can rarely be done outside specialist clinics.
Secondly, for practical reasons the ankle-brachial pressure ratio should be measured at the peroneal (fibular) artery rather than the posterior tibial artery or dorsalis pedis, as mentioned in the clinical review. The peroneal artery in the leg is also comparatively spared from calcification and thus offers the best available option.3
Thirdly, the review mentions identifying four “classic” risk factors for developing problems with the diabetic foot, but these often blur the picture. Symptoms such as pain in the foot or leg while resting or during sleep indicate critical ischaemia in patients without diabetes, but diabetic patients have a higher incidence of nocturnal muscle cramping, which is not due to arterial insufficiency. Assessment of pulse in an oedematous, ulcerated foot may not be possible, and infection of foot ulcers because of neuropathy often masks the subtle signs of arterial insufficiency—such as changes in skin colour associated with raising or lowering the foot.4
Early referral to a specialist multidisciplinary team is essential to reduce complications such as amputation. The interplay of all contributing factors needs to be considered carefully, rather than simply relying on just one test or pressure readings in diabetic patients.
Competing interests: None declared.
References
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