title: Global versus local linear beat-to-beat analysis of the relationship between arterial pressure and pulse transit time during dynamic exercise.
abstract: Global linear analysis has been traditionally performed to verify the relationship between pulse transit time (PTT) and systolic arterial pressure (SAP) at the level of their spontaneous beat-to-beat variabilities: PTT and SAP have been plotted in the plane (PTT,SAP) and a significant linear correlation has been found. However, this relationship is weak and in specific individuals cannot be found. This result prevents the utilization of the SAP-PTT relationship to derive arterial pressure changes from PTT measures on an individual basis. We propose a local linear approach to study the SAP-PTT relationship. This approach is based on the definition of short SAP-PTT sequences characterized by SAP increase (decrease) and PTT decrease (increase) and on their search in the SAP and PTT beat-to-beat series. This local approach was applied to PTT and SAP series derived from 13 healthy humans during incremental supine dynamic exercise (at 10, 20 and 30% of the nominal individual maximum effort) and compared to the global approach. While global approach failed in some subjects, local analysis allowed the extraction of the gain of the SAP-PTT relationship in all subjects both at rest and during exercise. When both local and global analyses were successful, the local SAP-PTT gain is more negative than the global one as a likely result of noise reduction.
authors.affiliation: Dipartimento di Scienze Precliniche, LITA di Vialba, Laboratorio di Modellistica di Sistemi Complessi, Universita degli Studi di Milano, Via G.B. Grassi 74, 20157, Milano, Italy. alberto.porta@unimi.it
authors.forename: A
authors.initials: A
authors.lastname: Porta
authors.forename: C
authors.initials: C
authors.lastname: Gasperi
authors.forename: G
authors.initials: G
authors.lastname: Nollo
authors.forename: D
authors.initials: D
authors.lastname: Lucini
authors.forename: P
authors.initials: P
authors.lastname: Pizzinelli
authors.forename: R
authors.initials: R
authors.lastname: Antolini
authors.forename: M
authors.initials: M
authors.lastname: Pagani
mesh_terms: D001158:Arteries; D001794:Blood Pressure / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D008954:Models, Biological; D011674:Pulse