title: Impact and management of physiological calibration in spectral analysis of blood pressure variability.
abstract: Physiological calibration (Physiocal) improves the quality of continuous blood pressure (BP) signal from finger. However, the effects of Physiocal on spectral characteristics of systolic BP (SBP) variability are not well-known. We tested the hypothesis that the use of Physiocal may alter the results on SBP variability when compared with BP recording without Physiocal. Continuous BP was recorded simultaneously from fingers of both arms during 10-min standing by two Nexfin devices, one with (ON) and the other without (OFF) Physiocal (n = 19). Missing SBP values in ON signal were linearly interpolated over Physiocal sequences (ONinter). The OFF signal was analyzed without any corrections (OFFreference) and after linear interpolation of corresponding sequences when Physiocal appeared in the ON signal (OFFinter). Mean low frequency power of SBP oscillations (LFSBP, 0.04-0.15 Hz) did not differ between the OFFreference, OFFinter, and ONinter. However, LFSBP deviated more from OFFreference when analyzed from ONinter compared with the analysis from OFFinter [median (interquartile range): 14.7 (4.6-38.6) vs. 0.9 (0.5-1.8) %, p < 0.05]. In conclusion, the use of Physiocal had a significant effect on the spectral SBP variability that overwhelms the impact of linear interpolation of short data sequences. Therefore, caution is needed when comparing SBP variability between BP datasets acquired with and without Physiocal.
authors.affiliation: Department of Exercise and Medical Physiology, Verve Research Oulu, Finland.
authors.forename: Antti M
authors.initials: AM
authors.lastname: Kiviniemi
authors.affiliation: Center for Environmental and Respiratory Health Research, University of Oulu Oulu, Finland ; Medical Research Center, University of Oulu Oulu, Finland.
authors.forename: Heidi
authors.initials: H
authors.lastname: Hintsala
authors.affiliation: Department of Exercise and Medical Physiology, Verve Research Oulu, Finland.
authors.forename: Arto J
authors.initials: AJ
authors.lastname: Hautala
authors.affiliation: Center for Environmental and Respiratory Health Research, University of Oulu Oulu, Finland ; Medical Research Center, University of Oulu Oulu, Finland ; Institute of Health Sciences, University of Oulu Oulu, Finland.
authors.forename: Tiina M
authors.initials: TM
authors.lastname: Ikäheimo
authors.affiliation: Center for Environmental and Respiratory Health Research, University of Oulu Oulu, Finland ; Medical Research Center, University of Oulu Oulu, Finland ; Institute of Health Sciences, University of Oulu Oulu, Finland.
authors.forename: Jouni J
authors.initials: JJ
authors.lastname: Jaakkola
authors.affiliation: Department of Computer Science and Engineering, University of Oulu Oulu, Finland.
authors.forename: Suvi
authors.initials: S
authors.lastname: Tiinanen
authors.affiliation: Department of Computer Science and Engineering, University of Oulu Oulu, Finland.
authors.forename: Tapio
authors.initials: T
authors.lastname: Seppänen
authors.affiliation: Department of Exercise and Medical Physiology, Verve Research Oulu, Finland ; Department of Applied Sciences, London South Bank University London, UK.
authors.forename: Mikko P
authors.initials: MP
authors.lastname: Tulppo
keywords: Nexfin; Physiocal; autonomic nervous system; self-adjustment; signal processing