Photoplethysmography can replace hand-held Doppler in the measurement of ankle/brachial indices

Ankle/brachial pressure index (ABPI) using hand-held Doppler and sphygmomanometer is a standard assessment for patients with peripheral arterial occlusive disease (PAOD). Good Doppler technique is difficult to master and so we investigated replacing Doppler with photoplethysmography (PPG). Two investigators examined 52 legs in 32 vascular patients. Both used standard sphygmomanometer cuff occlusion. Restoration of flow was detected by either an 8 MHz Doppler ultrasound probe or a PPG transmitter/receiver on index finger or great toe. Doppler-derived ABPIs were compared with PPG-derived ABPIs. Excellent correlation was found between both indices (correlation coefficient 0.875). Four lower limbs had unrecordable PPG traces, one also having an unrecordable Doppler signal. Excluding these four patients, the correlation coefficient rose to 0.975. PPG placed on the pulp of a digit can replace the hand-held Doppler in measuring ABPIs.