Accurate Detection of Dobutamine-induced Haemodynamic Changes by Kino-Cardiography: A Randomised Double-Blind Placebo-Controlled Validation Study

Abstract

Non-invasive remote detection of cardiac and blood displacements is an important topic in cardiac telemedicine. Here we propose kino-cardiography (KCG), a non-invasive technique based on measurement of body vibrations produced by myocardial contraction and blood flow through the cardiac chambers and major vessels. KCG is based on ballistocardiography and measures 12 degrees-of-freedom (DOF) of body motion. We tested the hypothesis that KCG reliably assesses dobutamine-induced haemodynamic changes in healthy subjects. Using a randomized double-blinded placebo-controlled crossover study design, dobutamine and placebo were infused to 34 volunteers (25 ± 2 years, BMI 22 ± 2 kg/m², 18 females). Baseline recordings were followed by 3 sessions of increasing doses of dobutamine (5, 10, 20 μg/kg.min) or saline solution. During each session, stroke volume (SV) and cardiac output (CO) were determined by echocardiography and followed by a 90 s KCG recording. Measured linear accelerations and angular velocities were used to compute total Kinetic energy (iK) and power (Pmax). KCG sorted dobutamine infusion vs. placebo with 96.9% accuracy. Increases in SV and CO were correlated to iK (r = +0.71 and r = +0.8, respectively, p < 0.0001). Kino-cardiography, with 12-DOF, allows detecting dobutamine-induced haemodynamic changes with a high accuracy and present a major improvement over single axis ballistocardiography or seismocardiography.

Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1

Randomised crossover design of the study. The study population was randomly assigned to one of two experimental groups. B represents baseline period, P1, P2 and P3 are periods of placebo infusion, and D1, D2 and D3 are periods of increasing doses of dobutamine infusion. The washout phase lasted at least 20 minutes.

Figure 2

Kino-cardiograph device measuring 2-lead ECG, 6-DOF seismocardiography (SCG) and 6-DOF ballistocardiography (BCG). The standard axis system is used for BCG and SCG: BCG x, y, and z are respectively left-to-right, caudocranial, and ventrodorsal axes; SGC x, y, and z are respectively right-to-left, caudocranial, and dorsoventral axes.

Figure 3

Waveform of (from top to bottom) SCG linear kinetic energy, SCG rotational kinetic energy, BCG linear kinetic energy, and BCG rotational kinetic energy for a representative subject at baseline (left) and then infused with increasing doses of dobutamine (5, 10, 20 μg/kg.min).

Figure 4

KCG parameters (means and 95% CI): (A) iKTotSCG, (B) iKTotSCG∗HR, (C) iKTotBCG, (D) iKTotBCG∗HR at baseline and at increasing doses of dobutamine or placebo (▴ Dobutamine; ⚬ Placebo).

Figure 5

Mean and 95% CI of (A) iKTotBCG and SV, (B) iKTotBCG∗HR and CO at baseline and increasing doses of dobutamine (5, 10, and 20 μg/kg.min). iKTotBCG and SV distinguished baseline, 5 μg/kg.min, and 10 μg/kg.min dobutamine dose levels, but not the 10 μg/kg.min to 20 μg/kg.min dobutamine dose levels. iKTotBCG∗HR and CO distinguished baseline, 5 μg/kg.min, 10 μg/kg.min, and 10 μg/kg.min dobutamine dose levels.