Inter-Limb BP difference

Compares systolic BP between the two arms and between arms and legs. An inter-arm difference of 10 mmHg or more raises cardiovascular risk, 15 mmHg or more points to vascular disease, and 20 mmHg or more to subclavian stenosis or, with acute chest or back pain, aortic dissection, which needs emergency CT angiography. Arm pressure 20 mmHg or more above the leg suggests coarctation of the aorta; popliteal pressure more than 20 mmHg above the brachial is Hill's sign of aortic regurgitation (graded mild, moderate and severe). With ankle pressures it also calculates the ankle-brachial index for peripheral arterial disease.