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Diurnal and position‐induced variability of impedance cardiography measurements in healthy subjects
Author(s) -
Tomsin Kathleen,
Mesens Tinne,
Molenberghs Geert,
Gyselaers Wilfried
Publication year - 2011
Publication title -
clinical physiology and functional imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.608
H-Index - 67
eISSN - 1475-097X
pISSN - 1475-0961
DOI - 10.1111/j.1475-097x.2010.00993.x
Subject(s) - medicine , reproducibility , intraclass correlation , impedance cardiography , coefficient of variation , orthostatic vital signs , stroke volume , cardiology , correlation coefficient , standard deviation , blood pressure , heart rate , statistics , mathematics
Summary Cardiovascular (CV) parameters and their measurements are subject to variation. In this study, we evaluated the reproducibility of impedance cardiography (ICG) measurements following orthostatic and diurnal challenges for a set of 22 CV parameters in ten randomly selected healthy nonpregnant women. A standard protocol was used to record a consecutive series of measurements for each parameter before and after three position changes. This series of measurements was performed twice (AM and PM sessions). For each parameter, measurement‐shift following position change was evaluated at 5% cutoff and compared between sessions. Intra‐ and intersession intraclass correlation (ICC) was calculated for individual measurements per position using repeated‐measures analysis of variance. Intra‐ and intersession Pearson’s correlation coefficient (PCC) was calculated for mean values per position. Intersession correlation for measurement‐shift following position change was 0·42 (5/12) for pressure parameters, whereas this was 0·96 (52/54) for other parameters. Inter‐ and intrasession ICC for individual measurements varied between 0·02 and 1 for all parameters, however inter‐ and intrasession PCC for mean values was consistently >0·80 for stroke volume (SV), stroke index (SI), cardiac output (CO), acceleration and velocity index (ACI and VI), thoracic fluid content (TFC), TFC index (TFCI) and heart period duration (HPD). We conclude that in healthy subjects under standardised conditions, reproducibility of means of multiple ICG measurements is high for SV, SI, CO, ACI, VI, TFC, TFCI and HPD. From our data, we cannot draw conclusions on trends in diseased subjects.