Abstract
Within-day and between-day reproducibility of supine and tilt baroreflex sensitivity
were investigated utilising sequence and spectral indices in 46 healthy adult males
employing 3 repeat measures; baseline, +60 min and +24 h. Reproducibility was assessed
via the 95% limits of agreement and by the technical error of the measurement. For
spectral parameters, the limits of agreement indicated same day was marginally better
than between-day reproducibility. For sequence parameters, between-day had marginally
better agreement than same-day reproducibility. Tilt markedly improved reproducibility
across all outcome measures. Precision expressed by the technical error of the measurement
for all spectral outcomes was good in both supine and tilt baroreflex sensitivity
(<6%). Precision was lower, but acceptable, for sequence baroreflex sensitivity outcomes
in both positions (<11%). Baroreflex sensitivity transfer gain provided the best agreement
and reproducibility during supine and tilt conditions. These findings suggest time
and spectral techniques may be employed to assess within-day and between-day baroreflex
sensitivity changes in healthy individuals. The inclusion of a tilt manoeuvre may
improve the reproducibility of the outcome measure, which may aid in the detection
of modest baroreflex sensitivity changes in studies employing limited sample sizes.
Key words
reliability - repeatability - sequence - spectral - supine - tilt
