Diurnal and position-induced variability of impedance cardiography measurements in healthy subjects

Abstract

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.

Maternal venous hemodynamics in gestational hypertension and preeclampsia

“…This impedance technique is a non-invasive method of evaluating haemodynamic parameters, based on thoracic resistance changes measured during each heart cycle of a high frequent, low powered electrical current using a set of 4 skin-electrodes [16,23]. …”

“…ICG-parameters were classified as pressure parameters, left ventricular output parameters, aortic flow parameters, and thoracic fluid content (TFC in 1/kOhm) [16,17]. Pressure parameters were systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP = SBP – DBP) and mean blood pressure (MBP = DBP + PP/3), all expressed in mmHg.…”

“…Combined electrocardiogram - Doppler ultrasonography (ECG-D) [13-15] and impedance cardiography (ICG) are non-invasive methods to study maternal hemodynamics, with acceptable reproducibility and repeatability when applied according to standardized protocols [16-20]. …”

Optimization of Simple Sphygmomanometric Blood Pressure Measurement in Routine Prenatal Care

“…The blood pressure measurements were performed as part of the Non-Invasive Continuous Cardiac Output Monitor assessment (NICCOMO, Medis Medizinische Messtechnik GmbH, Ilmenau, Germany) by use of an oscillometric sphygmomanometer at standardized time-points in a previously reported protocol [18]. Each patient performed the complete ICG examination first in supine position and afterwards in standing position.…”

Impedance cardiography: Recent advancements

“…An interesting study was performed by Tomsin et al [14] on diurnal and position-induced variability of ICG measurements in healthy subjects. They concluded that in healthy subjects under standardized conditions, reproducibility of means of multiple ICG measurements is high for most of the indices based on SV and CO.…”