title: Estimation of the total peripheral resistance baroreflex impulse response from spontaneous hemodynamic variability.
abstract: We previously developed a mathematical analysis technique for estimating the static gain values of the arterial total peripheral resistance (TPR) baroreflex (G(A)) and the cardiopulmonary TPR baroreflex (G(C)) from small, spontaneous beat-to-beat fluctuations in arterial blood pressure, cardiac output, and stroke volume. Here, we extended the mathematical analysis so as to also estimate the entire arterial TPR baroreflex impulse response [h(A)(t)] as well as the lumped arterial compliance (AC). The extended technique may therefore provide a linear dynamic characterization of TPR baroreflex systems during normal physiological conditions from potentially noninvasive measurements. We theoretically evaluated the technique with respect to realistic spontaneous hemodynamic variability generated by a cardiovascular simulator with known system properties. Our results showed that the technique reliably estimated h(A)(t) [error = 30.2 +/- 2.6% for the square root of energy (E(A)), 19.7 +/- 1.6% for absolute peak amplitude (P(A)), 37.3 +/- 2.5% for G(A), and 33.1 +/- 4.9% for the overall time constant] and AC (error = 17.6 +/- 4.2%) under various simulator parameter values and reliably tracked changes in G(C). We also experimentally evaluated the technique with respect to spontaneous hemodynamic variability measured from seven conscious dogs before and after chronic arterial baroreceptor denervation. Our results showed that the technique correctly predicted the abolishment of h(A)(t) [E(A) = 1.0 +/- 0.2 to 0.3 +/- 0.1, P(A) = 0.3 +/- 0.1 to 0.1 +/- 0.0 s(-1), and G(A) = -2.1 +/- 0.6 to 0.3 +/- 0.2 (P < 0.05)] and the enhancement of G(C) [-0.7 +/- 0.44 to -1.8 +/- 0.2 (P < 0.05)] following the chronic intervention. Moreover, the technique yielded estimates whose values were consistent with those reported with more invasive and/or experimentally difficult methods.
authors.affiliation: Department of Electrical and Computer Engineering, Michigan State University, 2120 Engineering Bldg., East Lansing, MI 48824, USA.
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Chen
authors.forename: Jong-Kyung
authors.initials: JK
authors.lastname: Kim
authors.forename: Javier A
authors.initials: JA
authors.lastname: Sala-Mercado
authors.forename: Robert L
authors.initials: RL
authors.lastname: Hammond
authors.forename: Rafat I
authors.initials: RI
authors.lastname: Elahi
authors.forename: Tadeusz J
authors.initials: TJ
authors.lastname: Scislo
authors.forename: Gokul
authors.initials: G
authors.lastname: Swamy
authors.forename: Donal S
authors.initials: DS
authors.lastname: O'Leary
authors.forename: Ramakrishna
authors.initials: R
authors.lastname: Mukkamala
mesh_terms: D000818:Animals; D001158:Arteries / Q000502:physiology; D017704:Baroreflex; D001794:Blood Pressure; D002302:Cardiac Output; D003187:Compliance; D003198:Computer Simulation; D003714:Denervation; D004285:Dogs; D006339:Heart Rate; D006439:Hemodynamics; D016014:Linear Models; D008955:Models, Cardiovascular; D005082:Physical Exertion / Q000502:physiology*; D011311:Pressoreceptors / Q000502:physiology*; D015203:Reproducibility of Results; D013997:Time Factors; D014655:Vascular Resistance