title: Spontaneous baroreflex by sequence and power spectral methods in humans.
abstract: Beat-by-beat variations in blood pressure and RR-interval are interrelated by the actions of baroreflex and non-baroreflex responses. This study had two purposes: (1) to examine the spontaneous relationships between RR-interval and systolic blood pressure to determine the relative occurrence of baroreflex and non-baroreflex responses in humans, and (2) to compare the beat-sequence method with a cross spectral estimate of the baroreflex response slope. Eight healthy men were studied during 10 h of quiet, seated rest, and six men and three women were studied during rest, rest plus fixed pace breathing, and a cold pressor test. RR-interval and continuous, non-invasive arterial blood pressure were measured with a computerized system. A baroreflex sequence was defined by a series of at least three consecutive heart beats in which systolic pressure and the following RR-interval either both increased or both decreased. A non-baroreflex relationship was defined by sequences of at least three beats by opposite directional changes of RR-interval and systolic pressure of that beat. The results showed that there were approximately 30% as many non-baroreflex compared to baroreflex slopes. Individual subject mean baroreflex and non-baroreflex slopes were highly correlated (r = 0.72, P < 0.001). Absolute slope values were not different, and they were unaffected by time, fixed pace breathing, or cold pressor test. The data showed the relatively simple beat-by-beat sequence method to yield spontaneous baroreflex response slopes that were quantitatively similar to, and highly correlated with (r = 0.85-0.94), baroreflex response slopes calculated by spectral analysis methods.
authors.affiliation: Laboratoire de Physiologie, Faculté de Médecine Grange-Blanche, Université Claude Bernard, Lyon, France.
authors.forename: R L
authors.initials: RL
authors.lastname: Hughson
authors.forename: L
authors.initials: L
authors.lastname: Quintin
authors.forename: G
authors.initials: G
authors.lastname: Annat
authors.forename: Y
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: C
authors.initials: C
authors.lastname: Gharib
mesh_terms: D000328:Adult; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D003080:Cold Temperature; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D010275:Parasympathetic Nervous System / Q000502:physiology; D011311:Pressoreceptors / Q000502:physiology; D012044:Regression Analysis; D015656:Respiratory Mechanics / Q000502:physiology; D012146:Rest / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology