Keywords: wearable impedance cardiography sensor, ICG sensor, thoracic bioimpedance sensor, wearable cardiac output monitor, continuous stroke volume sensor
Continuous Impedance Cardiography for Stroke Volume, Cardiac Output and Hemodynamic Assessment
Advanced wearable impedance cardiography (ICG) sensor for non-invasive, beat-to-beat measurement of hemodynamic parameters — designed for integration into the PCARDIO wearable monitoring platform.
- Tetrapolar BioZ acquisition
- Synchronized ECG + ICG channels
- Beat-to-beat stroke volume and cardiac output
- Raw dZ and dZ/dt available
- Validated algorithms (Kubicek / Bernstein)
TECHNICAL OVERVIEW
Engineering-Grade ICG Acquisition Module
The PCARDIO wearable impedance cardiography sensor is built for organizations developing next-generation hemodynamic monitoring systems. Unlike general-purpose bioimpedance front-ends, this module is optimized specifically for reliable capture of the thoracic impedance signal (ΔZ) and its time derivative (dZ/dt) — the signals from which stroke volume, cardiac output, and systolic time intervals are derived.
Since blood is the dominant conductor in the thoracic cavity, changes in thoracic impedance are directly proportional to changes in blood volume, and therefore to the amount of blood pumped per heartbeat. The sensor captures these small impedance variations with sufficient resolution to resolve the characteristic A, B, C, X, Y and O fiducial points on the ICG waveform — the features needed for clinical and research-grade hemodynamic analysis.
Significant engineering effort has gone into the current source stability, differential voltage sensing, electrode configuration, and motion artifact handling so the sensor performs reliably outside the bedside environment.
WEARABLE INTEGRATED
Optimized for Real-World Hemodynamic Monitoring
ICG has traditionally been confined to bedside and clinic use. This wearable impedance cardiography sensor is designed to operate inside ambulatory monitoring systems where the signal environment is far less controlled.
Typical challenges addressed include:
- motion artifacts during daily activity and exercise
- respiratory interference on the impedance baseline
- electrode-skin contact variability over multi-day wear
- electrode placement tolerance
- synchronized multi-sensor operation with ECG, PPG, motion and acoustic channels
- long-duration continuous acquisition
The result is a practical route to continuous, non-invasive stroke volume and cardiac output measurement in ambulatory, field, and home-monitoring conditions.
Tetrapolar electrode configuration: two current injection electrodes (neck and lower rib cage) and two voltage sensing electrodes between them, with ≥5 cm separation — compatible with single-sided chest placement or bilateral 8-electrode configurations.
SYNCHRONIZED ECG + ICG
ECG-Timed Segmentation for Reliable Parameter Extraction
Stroke volume, pre-ejection period (PEP), and left ventricular ejection time (LVET) can only be computed reliably when ICG events are referenced against the electrical activity of the heart. The PCARDIO platform acquires ECG and ICG on the same hardware clock, so the R-peak of the QRS complex and the A, B, C and X points of the ICG waveform are temporally aligned with sub-millisecond accuracy.
This enables:
- accurate PEP measurement (Q-onset to aortic valve opening / ICG B-point)
- accurate LVET measurement (B-point to X-point / dicrotic notch)
- robust B-point detection even when the ICG upstroke is ambiguous
- beat-by-beat rejection of motion-corrupted cycles
- electromechanical coupling analysis
Without synchronized ECG, the timing errors propagate directly into every derived hemodynamic parameter.
PROCESSING
ICG Feature Extraction and Smart Data Reduction
Continuous raw BioZ streaming generates large datasets. The platform includes dedicated processing software that can:
- detect fiducial points (A, B, C, X, Y, O) on the dZ/dt waveform
- compute beat-to-beat stroke volume using the Sramek-Bernstein formula
- track static thoracic impedance Z₀ for thoracic fluid content (TFC) estimation
- reduce data size while preserving diagnostically relevant waveform detail
- flag low-quality beats for downstream filtering
- optimize streaming for PCARDIO wearable systems and longer battery life
This creates an efficient balance between raw signal access and wearable usability. The exact strategy can be adapted to the target use case, whether the goal is ambulatory stroke volume tracking, synchronized multimodal analysis, or raw research data collection.
HEMODYNAMIC PARAMETERS
Hemodynamic Analytics (SV, CO, PEP, LVET, TFC)
PCARDIO has validated algorithms available to extract the full set of ICG-derived hemodynamic parameters:
- Stroke Volume (SV) — beat-to-beat pumped blood volume
- Cardiac Output (CO)
- Heart Rate (HR)
- Pre-Ejection Period (PEP) —
Amarker of cardiac contractility - Left Ventricular Ejection Time (LVET)
- Systolic Time Ratio (STR)
- Thoracic Fluid Content (TFC) — relevant for heart failure monitoring
- Systemic Vascular Resistance (SVR) — when combined with blood pressure input
This supports use cases where the interest is not only in storing raw ICG data, but also in obtaining structured hemodynamic features for scientific analysis, clinical research, algorithm development, and system integration.
This supports:
- AI and machine learning model development
- heart failure monitoring and decompensation detection
- continuous cardiac output monitoring outside the ICU
- cardiovascular autonomic and stress research
- wearable hemodynamic biomarker discovery
RAW DATA ACCESS
Raw BioZ + ICG Data for Research
For engineering teams and scientific users, the device provides direct access to the raw impedance signal (ΔZ) and its time derivative (dZ/dt), time-synchronized with ECG, motion, and any other active sensor channels on the platform.
Ideal for:
- custom algorithm development and validation
- machine learning datasets for cardiac output estimation
- comparison studies against Doppler echocardiography or thermodilution references
- electrode configuration and placement research
- hemodynamic biomarker discovery
POSSIBLE APPLICATIONS
Built for Clinicians, Engineers and Product Developers
For Clinicians & Clinical Researchers
Use this if your focus is patient monitoring, cardiovascular studies, or physiological outcomes.
Benefits:
- Continuous non-invasive stroke volume monitoring
- Beat-to-beat cardiac output trends
- PEP, LVET and TFC metrics available
- Supports heart failure and fluid management research
- Ambulatory hemodynamic monitoring outside ICU settings
- Synchronized ECG + ICG improves timing accuracy
Typical applications:
- Heart failure monitoring
- Autonomic function testing
- Cardiac rehab studies
- Remote patient monitoring pilots
For Engineers & Data Scientists
Use this if your focus is signal quality, raw data access, algorithm development, or validation.
Benefits:
- Raw ΔZ, dZ/dt and synchronized ECG access
- High-resolution ICG signal acquisition
- Time-aligned motion and multi-sensor data
- Fiducial point detection datasets (A, B, C, X, O)
- Ideal for AI / ML model development
- Export-ready research workflows
Typical applications:
- Stroke volume estimation algorithms
- Signal processing research
- Motion artifact reduction models
- Sensor fusion pipelines
For Product Developers & OEM Teams
Use this if you are building a commercial wearable or clinical monitoring product.
Benefits:
- Ready-to-integrate validated ICG signal chain
- Faster route to wearable hemodynamic products
- Lower R&D risk vs building from scratch
- Supports OEM customization
- Multi-sensor architecture available
- Scalable prototype-to-production pathway
Typical applications:
- Heart failure wearables
- Home monitoring devices
- Clinical trial devices
- Remote care platforms
WHY PARDIO
Designed around signal usefulness, not just impedance measurement
Many bioimpedance front-ends can measure a thoracic impedance value. The engineering challenge is to capture a usable ICG waveform — with resolvable fiducial points and stable baseline — when the sensor must operate inside a wearable system on a moving subject, over multi-day wear, and in synchronization with other modalities. This module has been developed with that challenge in mind: preserving the clinically and scientifically relevant features of the ICG signal while fitting within a scalable embedded platform.
For teams working on next-generation hemodynamic monitoring systems, this provides a practical route from raw BioZ acquisition to validated stroke volume, cardiac output, and systolic time interval outputs, with synchronized multi-sensor context and product-oriented system integration.
Looking for a Wearable Impedance Cardiography Sensor?
Whether you are building a heart failure monitoring prototype, running a hemodynamic research program, or developing an OEM cardiac health monitoring product, PCARDIO can accelerate development.
