Photoplethysmography, an easy and accurate method for measuring ankle brachial pressure index: can photoplethysmography replace Doppler?

ABSTRACT

OBJECTIVE: To assess the accuracy of ankle brachial pressure index (ABPI) assessed by photoplethysmography (PPG) compared with continuous wave Doppler (CW-Doppler). METHODS: Ankle brachial pressure index was measured in a standard manner using both PPG and Doppler probes. For PPG-ABPI, a PPG probe was placed on the index finger and great toe, and a microcomputer determined the ABPI. These values were compared with the ABPI measured manually using an 8-MHz Doppler probe. Correlation and agreement between PPG and Doppler ABPI were assessed by Lin's correlation coefficient and Bland-Altman plots. RESULTS: In all, 133 claudicants were assessed. There was a strong correlation between the 2 ABPI methods (beta = .79 and 95% limits of agreement of -0.23 to 0.24). CONCLUSION: Measuring ABPI automatically using the PPG technique is an effective alternative for Doppler ABPI. PPG-ABPI is completely objective, fast, and accurate.