Trends in heart rate and blood pressure during noninvasive BRS assessment

Spectral baroreflex sensitivity (BRS) assesment ideally requires haemodynamic and autonomic stationarity. On the other hand, there is a methodological tendency to increase the observation period in an attempt to improve the signal-to-noise ratio, but stationarity is more difficult to attain with a longer observation period. In this paper, we investigate the possible existence of trends in systolic blood pressure and inter-beat interval during highly-conditioned prolonged recordings. For this purpose, we recorded the ECG signal and the Finapress blood pressure signal for 10 minutes under 0.25-Hz metronome breathing. In 66 out of 73 subjects, trends could be demonstrated. Our study suggests that a fully stationary haemodynamic and autonomic state cannot be archieved in conscious humans with fully operational blood pressure control mechanisms