Noninvasive estimation of central blood pressure and the augmentation index in the seated position: a validation...

The aim of this study was to examine the utility of the generalized transfer function (GTF) and the late systolic shoulder of the radial pressure waveform (SBP2) for estimating seated central systolic blood pressure (c-SBP) and seated c-augmentation index (c-AIx).

In 199 participants (182 cardiovascular disease patients and 17 normal individuals; mean age: 65.7 ± 10.6 years), c-SBP and c-AIx were estimated using the SphygmoCor and Omron HEM-9000AI systems. Both estimates were compared with carotid SBP and augmentation index (AIx). All measurements were performed with the participants in the seated position.

Mean c-SBP was 121.7 ± 18.6 mmHg and 122.6 ± 19.8 mmHg according to the GTF and SBP2 methods, respectively, and carotid SBP was 124.4 ± 19.2 mmHg. There were close correlations between the three values (GTF vs. carotid SBP: r = 0.986, SBP2 vs. carotid SBP: r = 0.975, GTF vs. SBP2: r = 0.989, all P < 0.0001), all of which met the AAMI SP10 criteria and the grade A British Society of Hypertension criteria. The relationship between c-AIx estimated using the GTF method and carotid AIx was comparable to that reported previously for supine individuals (r = 0.703, P < 0.0001). The seated carotid-radial artery amplifications of the first and second harmonics were identical to those reported in previous supine studies. Both methods produced reproducible estimates of c-SBP and c-AIx (r = 0.997-0.910, all P < 0.0001).

The present study indicates that the GTF and SBP2 methods can be used to estimate c-SBP and c-AIx in seated individuals.