The feasibility for dicrotic augmentation index to replace tidal augmentation index

Aortic augmentation index (AI) has great significance in predicting cardiovascular diseases. To obtain AI the tidal wave crest will be need, which is difficult to identify sometimes. Fortunately, it is easier to obtain the dicrotic wave crest, which can derive a parameter called dicrotic augmentation index (DAI). In this paper the AIs and DAIs of the pulse waves acquired from 20 subjects including young healthy volunteers (n=20), were compared. The differential method combined with threshold was employed to extract the key feature points. Then the value of AI and DAI can be calculated. Their linearly dependent coefficient was estimated by using the weighted least square method, and the consistency check was performed by t-test and Bland-Altman algorithm. It is notable that the values of AI and DAI are in acceptable agreement (R=0.672), and the dependent equation is y=-0.0045+0.7528x (x and y represents AI and DAI, respectively). However, the agreement varied with the postures of volunteers. In the standing and sitting postures, the agreements were not as close as that corresponding to the posture of lying. The R corresponding to the standing and sitting postures is 0.48 and 0.50, respectively; while the R corresponding to the lying posture of the volunteer is 0.67, demonstrating a closer agreement.