Baroreceptor sensitivity in human subjects: sequence or spectral analysis?

The relationship between spectral analysis (SPa) and sequence analysis (SQa) for estimation of baroreceptor sensitivity (BRS) was studied in 17 patients (age range 59-75 years). Significant sequences detected by SQa were used to decompose beat-to-beat sequences of pulse interval and systolic arterial pressure into a linearized and a residual component and SPa was performed on both components and the original signals. Band-pass filtering was also performed on the original data preceding SQa. SQa estimates (8.49/spl plusmn/3.86 ms/mmHg) were in agreement with the alpha index of SPa (8.21/spl plusmn/4.15 ms/mmHg, r=0.86). Low-pass filtering produced significantly smaller values of BRS by SQa but these agreed with SPa estimates derived from the LF band. Conversely, high-pass filtering did not affect the SQa estimates but better agreement was obtained with SPa estimates based on the HF band. Our main conclusion is that the two methods share common elements and therefore one should not be ruled out to the detriment of the other, except in circumstances in which non-stationarity precludes SPa.