Motion robust ICG measurements using a two-step spectrum denoising method

Abstract

Objective. Impedance cardiography (ICG) is a noninvasive and continuous method for evaluating stroke volume and cardiac output. However, the ICG measurement is easily interfered due to respiration and body movements. Taking into consideration about the spectral correlations between the simultaneously collected ICG, electrocardiogram (ECG), and acceleration signals, this paper introduces a two-step spectrum denoising method to remove motion artifacts of ICG measurements in both resting and exercising scenarios. Approach. First, the major motion artifacts of ECG and ICG are separately suppressed by the spectral subtraction with respect to acceleration signals. The obtained ECG and ICG are further decomposed into two sets of intrinsic mode functions (IMFs) through the ensemble empirical mode decomposition. We then extract the shared spectral information between the two sets of IMFs using the canonical correlation analysis in a spectral domain. Finally, the ICG signal is reconstructed using those canonical variates with largest spectral correlations with ECG IMFs. Main results. The denoising method was evaluated for 30 subjects under both resting and cycling scenarios. Experimental results show that the beat contribution factor of ICG signals increases from its original 80.1%–97.4% after removing the motion artifacts. Significance. The proposed denoising scheme effectively improves the reliability of diagnosis and analysis on cardiovascular diseases relying on ICG signals.

Porous liquid metal–elastomer composites with high leakage resistance and antimicrobial property for skin-interfaced bioelectronics

“…The critical characteristic points in ICG are also clearly observable, including B, C, X, and O that represent the opening of the aortic valve, maximum ejection velocity, closing of the aortic valve, and opening of the mitral valve, respectively ( 45 ). The pre-ejection period (i.e., time elapse between the Q point in ECG and B point in ICG) represents the period of left ventricular contraction with cardiac valves closed, indicative of heart sympathetic innervation ( 47 ). Because of the porous EGaIn composite’s large stretchability, ultrasoftness, and stable conductance over strain, the obtained skin-interfaced electrodes and interconnection cables can enable steady biosignal recording with high signal-to-noise ratios (SNRs) under dynamic deformations ( Fig.…”

“…Monitoring heart electrical activity via ECG outside clinical settings plays an indispensable role in diagnosis of heart diseases (43,44). Concurrent measurement of cardiac mechanical function by ICG can reveal critical information that complements those associated with ECG (45)(46)(47). The wearable system based on porous EGaIn composites can perform high-fidelity ECG and ICG recording even during motions.…”

Lymph Node Mapping for Tumor Micrometastasis

“…ICG is a tricarbocyanine dye that was developed using NIR technology in 1955 and permitted by the Food and Drug Administration (FDA) immediately for clinical use . ICG is widely employed in cancer diagnosis and other fields including angiography, cardiac output assessment, hepatic function evaluation, endoscopic endonasal surgery, and photodynamics and photothermal therapy. − In addition to the above applications, the ICG application for SLN is also promising. ICG-guided SLN biopsy reduces surgical time and improves lymph node detection, remaining an intact surgical anatomy .…”

A New Method of Identifying Characteristic Points in the Impedance Cardiography Signal Based on Empirical Mode Decomposition

“…In [ 50 , 51 , 52 ], it was shown that EMD can be extremely useful in the identification of cardiovascular diseases. It also facilitates the detection of characteristic points of this signal [ 53 ] and allows for effectively suppressing noise without losing significant features in the acquired recordings [ 54 , 55 ]. Here, we propose a novel, EMD-based method that allows for the accurate detection of fiducial points in the ICG signal.…”