title: Patterns of cardiovascular control during repeated tests of orthostatic loading.
abstract: To investigate patterns of cardiovascular control, a protocol of head up tilt (HUT) followed by lower body negative pressure (LBNP), which represents a significant cardiovascular control challenge, was employed. Linear regression of beat-to-beat heart rate (HR) and mean blood pressure (MBP) data collected over repeated tests was used to analyze control response during the LBNP phase of the combined HUT + LBNP protocol. Four runs for each of 10 healthy young males reaching presyncope were analyzed. Subjects were classified into 2 groups based on the consistency of MBP regulation in response to central hypovolemia induced by LBNP. The consistent group tended to exhibit consistent HR slope (rate of change of HR over time as calculated by linear regression) whereas subjects in the inconsistent group could not be easily classified. Subjects with consistent MBP maintenance exhibited patterns suggesting a consistency of response in cardiovascular control whereas subjects less successful in maintaining MBP exhibited less clearly defined patterns over four runs.
authors.affiliation: Institute for Mathematics and Scientific Computing, University of Graz, Heinrichstrasse 36, 8010, Graz, Austria. jerry.batzel@uni-graz.at
authors.forename: Jerry Joseph
authors.initials: JJ
authors.lastname: Batzel
authors.forename: Nandu
authors.initials: N
authors.lastname: Goswami
authors.forename: Helmut Karl
authors.initials: HK
authors.lastname: Lackner
authors.forename: Andreas
authors.initials: A
authors.lastname: Roessler
authors.forename: Mostafa
authors.initials: M
authors.lastname: Bachar
authors.forename: Franz
authors.initials: F
authors.lastname: Kappel
authors.forename: Helmut
authors.initials: H
authors.lastname: Hinghofer-Szalkay
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology*; D003198:Computer Simulation; D004244:Dizziness / Q000503:physiopathology*; D025461:Feedback, Physiological / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008150:Lower Body Negative Pressure; D008297:Male; D008955:Models, Cardiovascular; D011187:Posture / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018667:Tilt-Table Test