Non-Invasive Cardiac Output

Overview

Impedance Cardiography (ICG) is a non-invasive cardiac output monitoring technology that utilizes thoracic impedance signals to calculate critical hemodynamic parameters. By measuring changes in thoracic electrical conductivity, ICG provides real-time assessment of cardiac output and blood flow, supporting clinical decision-making in various care settings.

Measurement Principles

Impedance Cardiography (ICG) operates using four electrodes: one pair injects a constant current, while the other measures resulting voltage changes. These voltage variations reflect changes in thoracic impedance caused by pulsatile blood flow.

The raw impedance signal (Z) is differentiated to produce the –dZ/dt waveform, highlighting key inflection points. Notable signal features include:

• B point :Atrial contraction (pre-systolic downward deflection)

• C point :Peak systolic flow (major upward deflection)

These points are identified in relation to the R-wave on the ECG for precise cardiac cycle alignment. Stroke volume is derived based on the timing and amplitude of these landmarks.

Advanced signal processing and artifact rejection algorithms are employed to maintain measurement accuracy amid motion and noise.

ICG Calculation Parameters

ICG Clinical Validation

A clinical study involving 13 patients (8 males, 5 females) demonstrated that ICG monitoring showed no complications and closely tracked cardiac output trends compared to LiDCOrapid and NICOM systems. While LiDCOrapid exhibited unexplained sudden output drops, ICG provided stable and consistent readings.

Conclusion:ICG cardiac output measurements demonstrated high consistency and low bias relative to LiDCOrapid and NICOM across diverse clinical conditions, validating its reliability for non-invasive hemodynamic monitoring.

ICG Clinical Benefits

• Enables accurate, non-invasive cardiac output monitoring for conditions such as heart failure, sepsis, trauma, and shock.
• Facilitates early detection and correction of volume status (hypo/hypervolemia).
• Supports perioperative and ICU hemodynamic management in high-risk patients.
• Optimizes fluid and inotrope administration via Goal-Directed Therapy (GDT).
• Enhances outcomes in Enhanced Recovery After Surgery (ERAS) protocols.
• Reduces ICU length of stay and resource utilization, improving cost-efficiency.

Advantage:Delivers validated, real-time hemodynamic data with high correlation to invasive standards, supporting precision-guided therapy.