Baroreflex sensitivity as an individual characteristic feature

The reproducibility of baroreflex sensitivity (BRS in ms/mmHg; BRSf in mHz/mmHg) determined with respect to the coherence between the variability in systolic blood pressure (SBP) and inter-beat intervals (IBI) or heart rate (HR) was tested. SBP and IBI were recorded beat-to-beat for 5 min (Finapres, breathing at 0.33 Hz) in 116 subjects (aged 19-24 years) sitting at rest three times in periods of one week. BRS and BRSf was determined by a cross-spectral method in a frequency range of 0.067-0.133 Hz. Eight indices were evaluated: BRS(0.1 Hz) /BRSf(0.1 Hz) - the value at a frequency of 0.1 Hz; BRS(COHmax)/BRSf(COHmax) - the value at maximum coherence; BRS(Wcoh)/BRSf - weighted value with respect to coherence values in the whole frequency range; BRS(WPcoh)/BRS(WPcoh) - weighted value with respect to coherence for frequencies with coherence above 0.5. All indices revealed a lower intraindividual than interindividual variability (p