This study compared spontaneous baroreflex sensitivity (BRS) estimates obtained from an identical set of data by 11 European centers using different methods and procedures. Noninvasive blood pressure (BP) and ECG recordings were obtained in 21 subjects, including 2 subjects with established baroreflex failure. Twenty-one estimates of BRS were obtained by methods including the two main techniques of BRS estimates, i.e., the spectral analysis (11 procedures) and the sequence method (7 procedures) but also one trigonometric regressive spectral analysis method (TRS), one exogenous model with autoregressive input method (X-AR), and one Z method. With subjects in a supine position, BRS estimates obtained with calculations of alpha-coefficient or gain of the transfer function in both the low-frequency band or high-frequency band, TRS, and sequence methods gave strongly related results. Conversely, weighted gain, X-AR, and Z exhibited lower agreement with all the other techniques. In addition, the use of mean BP instead of systolic BP in the sequence method decreased the relationships with the other estimates. Some procedures were unable to provide results when BRS estimates were expected to be very low in data sets (in patients with established baroreflex failure). The failure to provide BRS values was due to setting of algorithmic parameters too strictly. The discrepancies between procedures show that the choice of parameters and data handling should be considered before BRS estimation. These data are available on the web site (http://www.cbi.polimi.it/glossary/eurobavar.html) to allow the comparison of new techniques with this set of results.

This is the first description of the BP response to an acute loud noise in humans. The early (within 10 s) BP and HR rises may depend upon the autonomic component of the startle reflex. One application of this test could be the discrimination of the different classes of antihypertensive drugs according to their sites of action.

1. Non-invasive continuous finger blood pressure (BP) measurement and a spectral technique based on the Fourier transform (FT) were recently combined to quantify short-term fluctuations in haemodynamic variables. 2. Systolic BP (SBP) recording combined low frequency (LF, Mayer waves) plus high frequency (HF, respiratory) oscillations. The presence of HF oscillations of SBP probably reflects fluctuations in cardiac output. Heart rate (HR) also exhibited a combination of low and HF (respiratory) oscillations. The vagus nerve mediates the efferent control of the respiratory sinus arrhythmia (RSA). 3. During controlled breathing in a supine position, a change in SBP is associated with an opposite consequent change in HR. Respiratory sinus arrhythmia could therefore depend on the baroreceptor-HR response to underlying SBP oscillations. 4. The fast regulation of R-R interval by SBP through the baroreceptor-HR reflex may explain why the respiratory variations in the diastolic BP are small.