Comparing analysis of heart rate and blood pressure fluctuations in healthy subjects

Heartbeat interval fluctuations exhibit fractal scaling behavior on certain time scales. However, less is known about blood pressure fluctuations and respiration. We compa re the short-term and long-term scaling properties of heartbeat intervals (HBI), systolic (SBP) and diastolic (DBP) blood pressure as well as respiratory (RES) time series based on recordings from 127 healthy subjects using centered moving average (CMA) anlysis and detrended fluctuation analysis (DFA1). We find that both methods are equivalent and long-term correlations of all four signals are similar, α2,HBI = 0.86 ± 0.15, α2,SBP = 0.83 ± 0.14, α2,DBP = 0.75 ± 0.15, and αRES = 0.68 ± 0.07. However, short-term exponents are strongly increased for blood pres sure, α1,SBP = 1.26 ± 0.20 and α1,DBP = 1.19 ± 0.17 compared with α1,HBI = 0.87 ± 0.23 for heartbeat. These results suggest that the long-term regulation of heart-rate and blood pressure is controlled in a similar fashion. The control of short-term fluctuations, however, is clearly different, with a non-stationary behavior of the blood pressure fluctuations. We also calcula te baroreflex sensitivity using the dual sequences method and study the cross-correlations between all exponents and bar o eflex sensitivities.