title: Reproducibility of three different methods of measuring baroreflex sensitivity in normal subjects.
abstract: 1. Baroreflex sensitivity is a useful tool for investigating cardiovascular reflexes in a number of clinical settings. Several different methods of measuring baroreflex sensitivity are available. In order to determine a clinically useful non-invasive method of measuring baroreflex sensitivity we compared two methods (spectral analysis and the Valsalva manoeuvre) with regard to reproducibility, agreement with a standard invasive method (phenylephrine infusion) and failure rate.2.Twenty-six healthy subjects aged 22 to 63 years attended on three separate occasions for measurement of baroreflex sensitivity using the different methods. The effect of a recent head-up tilt on baroreflex sensitivity was measured.3. Reproducibility was best for the low-frequency component of the spectral method [coefficient of variation 25.0% (range 3.5-42.4%)] and worst for the Valsalva method [coefficient of variation 29.3% (range 13.8-93.1%)]. Both non-invasive methods overestimated values compared with the phenylephrine method [bias of low-frequency component of the spectral method, 1.17 (0.38-3.6); bias of the Valsalva method, 1.13 (0.19-6.7)]. The high-frequency component of the spectral method did not agree with the phenylephrine method.4. The spectral analysis method had the fewest failures (seven subjects with a failure on at least one occasion), and the phenylephrine method the most (16 subjects with a failure on at least one occasion). A short head-up tilt did not affect the subsequent non-invasive measurement of baroreflex sensitivity.5. It was concluded that the low-frequency component of the spectral method was the most clinically useful non-invasive measurement of baroreflex sensitivity.
authors.affiliation: Cardiovascular Investigation Unit, Royal Victoria Infirmary, Newcastle upon Tyne NE1 4LP, U.K.
authors.forename: S W
authors.initials: SW
authors.lastname: Lord
authors.forename: R H
authors.initials: RH
authors.lastname: Clayton
authors.forename: M C
authors.initials: MC
authors.lastname: Hall
authors.forename: J C
authors.initials: JC
authors.lastname: Gray
authors.forename: A
authors.initials: A
authors.lastname: Murray
authors.forename: J M
authors.initials: JM
authors.lastname: McComb
authors.forename: R A
authors.initials: RA
authors.lastname: Kenny
mesh_terms: D000328:Adult; D017704:Baroreflex; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010656:Phenylephrine; D010991:Plethysmography; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013566:Sympathomimetics; D018667:Tilt-Table Test; D014636:Valsalva Maneuver
chemical_list: D013566:Sympathomimetics; D010656:Phenylephrine