Bioimpedance Methods

Related Hardware

Compatible with MP160

Smart Amplifiers NICO100D Cardiac Output, EBI100D Electrical Bioimpedance

Amplifiers NICO100C Cardiac Output, EBI100C Electrical Bioimpedance

MRI NICO100C-MRI Cardiac Output Amplifier

Wireless BN-NICO Cardiac Output Amplifier & BN-NICO-T Transmitter

Compatible with MP36 and MP36R (4-channel DAQ)

Module  SS31LA Impedance Cardiography Sensor with leads

Factors that Affect Bioimpedance Data

• System bandwidth. Historical algorithms for ICG make assumptions about ICG bandwidth that are not commonly broadcast. For example, a 10 Hz LPF will act to limit the spikiness of the ICG waveform, so that it looks “clean” but if the algorithm implies peak dZ/dt as an input, then the estimated stroke volume will shift. However, this arrangement will continue to work well to provide relative changes in stroke volume.
• Electrode type. The typical reference in old literature is circumferential tape; newer methods use paired spot electrodes.
• Electrode placement. Location and position is hyper-critical. For example, TREV is far more stable than ICG, due to the simplicity of the internal forearm, compared to the complexity of the torso (with lungs, big vessels, etc.).
• Participant position. Standing/supine: fluids shift in the torso, between these states, thus radically affecting the torso base impedance.

USAGE STATEMENT

Bioimpedance methods to perform stroke volume and cardiac output measurements, via application of electrodes on the neck and torso, are considered by BIOPAC to be research and educational tools.

Historically, there have been numerous research efforts to measure stroke volumes and cardiac outputs using bioimpedance techniques. The performance of these systems are subject to evolving algorithms. New bioimpedance methods, such as TREV (TransRadial Electrical bioimpedance Velocimetry), are examples showing new promise in this area. Additionally, machine learning strategies are beginning to accommodate the variabilities of bioimpedance methods, due to electrode type, placement, body position, movement artifact and electrical signal filtering.

Research is ongoing, as bioimpedance techniques offer profound noninvasive advantages, compared to thermodilution and similar “gold-standard” historical methods for measuring stroke volume and cardiac output. BIOPAC is committed to continuing to offer educational and research solutions for the application of bioimpedance methods, to measure cardiovascular parameters, despite the present “state of the art” showing these measures to be generally more useful for determining relative changes versus absolute values.