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Effects of posture and breathing frequency on baroreflex measurements

Lookup NU author(s): Emma Bowers, Emeritus Professor Alan MurrayORCiD


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The aim of this study was to assess the influences of posture and breathing frequency on baroreflex measurements.Six normal healthy volunteers breathed regularly at 6, 8, 10, and 12 breaths per minute each in a supine, sitting and standing position. Beat-to-beat RR-intervals and systolic pressure levels were calculated from raw ECG and Finapres signals. The time offset between positive RR-interval changes' and subsequent negative systolic pressure level changes was calculated by cross correlation. Baroreflex sensitivity was calculated from the frequency domain of RR-interval and systolic pressure levels changes, using the ratio of the height of the peaks at each breathing frequency.Time offset significantly decreased by 1.83 +/- 0.69s (mean +/- SD) (p<0.001) when breathing rate increased from 6 to 12 breaths per minute. Posture had no influence. Baroreflex sensitivity decreased by 20.1 +/- 18.5 ms/mmHg (mean +/- SD) (p<0.01) as posture changed from supine to standing, but was independent of breathing frequency.Posture and breathing frequency are two factors of many that can influence baroreflex measures. These preliminary results show that a better understanding of their effects is needed to allow repeatable measurement protocols to be developed.

Publication metadata

Author(s): Bowers EJ, Murray A

Publication type: Conference Proceedings (inc. Abstract)

Publication status: Published

Conference Name: Computers in Cardiology 2002

Year of Conference: 2002

Pages: 469-472

Online publication date: 22/01/2003

ISSN: 0276-6547

Publisher: IEEE


DOI: 10.1109/CIC.2002.1166811

Library holdings: Search Newcastle University Library for this item

ISBN: 0780377354