Baroreflex Sensitivity Evaluation Using the Volterra–laguerre Technique

The short-term blood pressure can be adjusted through baroreflex control and the quantitative index of the regulation is baroreflex sensitivity (BRS). The noninvasive spontaneous BRS is mostly estimated by using linear model techniques either in the time domain or in the frequency domain. However, the complex physiological regulatory mechanism of blood pressure has nonlinear response characteristics. In this study, the nonlinear Volterra mathematical model and the orthogonal Laguerre function were used to obtain the BRS through the identified model parameters. The Volterra–Laguerre (VL) technique was used to analyze all samples in the EuroBaVar dataset. The results were compared with the BRS estimates obtained by the alpha coefficient (Alpha) technique and the sequence (SEQ) technique. The BRS values obtained with the VL technique in both supine and standing positions were significantly lower than those obtained through the Alpha and SEQ techniques (VL:9.8 ± 10.0, SEQ:19.9 ± 13.4 and Alpha:19.0 ± 15.0 ms/mmHg, in supine; VL:3.5 ± 2.3, SEQ:9.1 ± 5.8 and Alpha:7.7 ± 5.6 ms/mmHg, in standing). The VL technique was able to evaluate the BRS of all samples, even in patients with low BRS, in the EuroBaVar dataset.