Mid- and Long-term Reproducibility of Noninvasive Measurements of Spontaneous Arterial Baroreflex Sensitivity in Healthy Volunteers

Abstract

Baroreflex sensitivity (BRS) is altered in a variety of circumstances and could be considered as a marker for the prognosis of some cardiovascular diseases. The present study was designed to evaluate the reproducibility of noninvasive measures of BRS, both at mid- and at long-term. Fourteen healthy volunteers were examined on three occasions (first interval = 1 week, second interval = 1 year). Each recording was performed using a noninvasive photoplethysmographic device (Finapres 2300, Ohmeda), both in supine and standing positions. Two different methods of measurement were used: the sequences method and cross spectral analysis. The reproducibility of BRS measures was as satisfactory at mid- as at long-term for the sequences method (intraclass coefficient [ICC] = 0.87 and 0.86, respectively), but it was better at mid- than at long-term for the cross-spectral analysis (ICC = 0.85 and 0.54, respectively). The measures performed in standing position were obviously more reproducible than those made in recumbent position (ICC = 0.87 and 0.70 for the sequences method, 0.85 and 0.71 for the cross-spectral analysis, respectively). Due to the high reproducibility of these noninvasive measures, the number of patients to be included in a pharmacological study was calculated as rather small: for example, only 20 patients are required for detecting a change in upright BRS of 3 msec/mm Hg, at long-term (sequences method). Likewise, the magnitude of the regression to the mean, which has to be expected in patients selected for a follow-up study, turned out to be low: for example, <15% of the difference between the patient group mean value and the reference value, both at mid- and at long-term (standing position, sequences method). We conclude that: 1) The noninvasive measures of BRS in standing position are reproducible enough to allow longitudinal studies to be conducted over either a short or a long period; 2) The long-term reliability of the sequences method seems to be higher than that of the cross-spectral analysis; and 3) Subtle changes in SBR may be noninvasively detected within small patient groups.

Measures of cardiovascular autonomic nervous function: agreement, reproducibility, and reference values in middle age and elderly subjects

“…Secondly, elderly people in general have more difficulties to correctly carry out certain tests (deep breathing and standing up quickly enough). This becomes apparent when comparing our reproducibility with other studies: somewhat higher reproducibility for the deep breathing test (EI difference and BRS) for slightly younger subjects [12,56,57,58]. Reproducibility of course might be improved by standardizing the conditions during measurements [56].…”

Is there a glycemic threshold for impaired autonomic control?

“…In the current study, we measured BRS with a noninvasive procedure involving cross-spectral analysis that derives BRS from the oscillations in R-R interval coincident with the blood pressure oscillations under resting conditions. Spectral analysis-derived estimates of BRS are significantly correlated with BRS estimated with more invasive measures (13,23) and show satisfactory short-term reproducibility (24,25).…”

Aging Process on Spectrally Determined Spontaneous Baroreflex Sensitivity

“…Because S-BRS is partly derived from SBP determination, any estimate of its time evolution is limited by the time evolution of the BP signal. Because S-BRS is reproducible in the short term 15,[23][24][25] and has a predictable evolution in the long term, S-BRS can be considered an intrinsic characteristic of each subject and therefore used in research studies and clinical practice.…”