Threshold sensitivity in time domain BRS estimation: Minimum beat-to-beat changes and minimum correlation

In the sequences technique, baroreflex sensitivity (BRS) is estimated as the slope between SBP and RR values in baroreflex sequences (BS). For BS identification, thresholds are applied to SBP and RR series and no recommendation on the appropriate values is given in the literature. Changes in their values can modify the number of BSs and the BRS estimate, making difficult to compare results from different studies, if not impossible. In this work, optimum thresholds values for the identification of baroreflex related events are given. The results in the EuroBaVar dataset indicate that BRS analysis can be improved if no minimum SBP and RR beat-to-beat changes are imposed and the minimum SBP-RR correlation is 0.8. This combination duplicates the number of beats (located in more and longer segments) with global SBP-RR correlation close to 0.8, without introducing substantial changes in BRS estimates distribution. Also, it makes possible to estimate the BRS when BSs are not identified.