False ABI in Diabetic Patients

Wound care clinicians rightly fear critical limb ischemia.

Without enough blood flow to sustain tissue life the patient faces the possibility of requiring an amputation or in the worse case scenario death. For most wound care specialists the treatment for the condition has been established. Obtain an ankle-brachial index (ABI) and apply compression. A series of recent studies calls into question the reliability of ABI for patients with advanced diabetes.

ABI compares the blood pressure measures at the ankle with the reading taken from a patient’s arm. The common threshold of a false ABI has been an ABI or 1.3 or higher. In 2011, the American College of Cardiology and the American Heart Association raised the number to 1.4.

It is common for patients with advanced diabetes to show normal or elevated ABI. False reads in ABI occurs due to calcification on the arterial wall. In a diabetic’s foot skin may die from chronic capillary ischemia even if total blood perfusion remains normal. In these cases compression might cause the patient’s condition to worsen or potentially become dangerous.

While wound care clinicians might be familiar with false ABIs

Anyone working in wound care needs to stay alert for false reports of elevated or normal ABIs in diabetic patients. In diabetic patients with a false ABI consider peripheral artery disease as a potential culprit.