title: First in vivo application and evaluation of a novel method for non-invasive estimation of cardiac output.
abstract: Surgical or critically ill patients often require continuous assessment of cardiac output (CO) for diagnostic purposes or for guiding therapeutic interventions. A new method of non-invasive CO estimation has been recently developed, which is based on pressure wave analysis. However, its validity has been examined only in silico. Aim of this study was to evaluate in vivo the reproducibility and accuracy of the "systolic volume balance" method (SVB). Twenty two subjects underwent 2-D transthoracic echocardiography for CO measurement (reference value of CO). The application of SVB method required aortic pressure wave analysis and estimation of total arterial compliance. Aortic pulses were derived by mathematical transformation of radial pressure waves recorded by applanation tonometry. Total compliance was estimated by the "pulse pressure" method. The agreement, association, variability, bias and precision between Doppler and SVB measures of CO were evaluated by intraclass correlation coefficient (ICC), mean difference, SD of differences, percentage error (PR) and Bland-Altman analysis. SVB yielded very reproducible CO estimates (ICC=0.84, mean difference 0.27 ± 0.73 L/min, PR = 16.7%). SVB-derived CO was comparable with Doppler measurements, indicating a good agreement and accuracy (ICC = 0.74, mean difference = -0.22 ± 0.364 L/min, PR ≈ 15). The basic mathematical and physical principles of the SVB method provide highly reproducible and accurate estimates of CO compared with echocardiography.
authors.affiliation: Biomedical Engineering Unit, 1st Dept. of Cardiology, Hippokration Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece; Laboratory of Hemodynamics and Cardiovascular Technology, Institute of Bioengineering, Swiss Federal Institute of Technology, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland. Electronic address: thepap@med.uoa.gr.
authors.forename: Theodore G
authors.initials: TG
authors.lastname: Papaioannou
authors.affiliation: Biomedical Engineering Unit, 1st Dept. of Cardiology, Hippokration Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Soulis
authors.affiliation: Laboratory of Hemodynamics and Cardiovascular Technology, Institute of Bioengineering, Swiss Federal Institute of Technology, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors.forename: Orestis
authors.initials: O
authors.lastname: Vardoulis
authors.affiliation: Cardiovascular Research Laboratory, 1st Dept. of Propaedeutic and Internal Medicine, Laikon Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Athanase
authors.initials: A
authors.lastname: Protogerou
authors.affiliation: Cardiovascular Research Laboratory, 1st Dept. of Propaedeutic and Internal Medicine, Laikon Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Petros P
authors.initials: PP
authors.lastname: Sfikakis
authors.affiliation: Laboratory of Hemodynamics and Cardiovascular Technology, Institute of Bioengineering, Swiss Federal Institute of Technology, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Stergiopulos
authors.affiliation: Biomedical Engineering Unit, 1st Dept. of Cardiology, Hippokration Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Christodoulos
authors.initials: C
authors.lastname: Stefanadis
mesh_terms: D000328:Adult; D001011:Aorta / Q000502:physiology; D001794:Blood Pressure; D002302:Cardiac Output; D005260:Female; D006334:Heart Function Tests / Q000379:methods*; D006801:Humans; D008297:Male
keywords: Aortic pressure wave; Arterial compliance; Cardiac output monitoring; Pulse contour analysis; Stroke volume