title: Validity of the adaptive filter for accurate measurement of cardiac output in impedance cardiography.
abstract: The purpose of this study was to assess the validity of an adaptive filter, the scaled Fourier linear combiner (SFLC), in the impedance cardiography (ICG). Eight healthy males underwent constant-load bicycle exercise at different intensities from unloaded to near maximal intensity. The stroke volume (SV) and cardiac output (Q) measured by ICG at each condition were compared with those by the CO2 rebreathing method. We found that the noises were greatly reduced in the impedance waveform and that the inflection points, so-called the B- and X-points, were clearly detected even during strenuous exercise using the SFLC. Although a high correlation was observed between Qs measured by the two methods, the mean values of Qs in each method differed significantly and the regression line also differed significantly from the identity line. Likewise, a significant correlation was observed between SVs obtained by the two methods, but a significant difference in the group mean values and a trend of the regression line were observed. These findings suggest that the use of SFLC in ICG improves the performance in eliminating the noises and in detecting the inflection points in the waveform, thereby contributing to the accurate and beat-to-beat measurements of SV and Q especially during exercise.
authors.affiliation: Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya 464-8601, Japan. tono@edogawa-u.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Ono
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Yasuda
authors.forename: Tomonori
authors.initials: T
authors.lastname: Ito
authors.forename: Allan K
authors.initials: AK
authors.lastname: Barros
authors.forename: Koji
authors.initials: K
authors.lastname: Ishida
authors.forename: Miharu
authors.initials: M
authors.lastname: Miyamura
authors.forename: Makoto
authors.initials: M
authors.lastname: Yoshizawa
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Yambe
mesh_terms: D000328:Adult; D002307:Cardiography, Impedance / Q000295:instrumentation* / Q000379:methods; D004562:Electrocardiography; D005080:Exercise Test; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D013223:Statistics as Topic