​Peripheral arterial disease (PAD) happens when narrowed arteries restrict blood circulation on the limbs. This is a important explanation for limb decline in Singapore. It monitors and compares hypertension while in the ankles into the arms. ABI ratios lower than 1.0 generally suggest diminished blood circulation, that is according to https://www.sgvascularctr.com/understanding-arterial-vein-disease-in-singapore/