Models designed to infer stroke volumes based on changes in thoracic impedance rely on many simplifying assumptions. These assumptions are not universally valid. Consequently the relationship between measured impedances and the absolute amount of blood moving into and out of the heart is not adequately characterized. For more background, see references cited in “What types of electrode should I use?”. AcqKnowledge offers different models via “Analysis > Impedance Cardiography > Preferences…”. The “Stroke Volume methods” are not proprietary; they have been taken from the ICG literature. If you would like to utilize a different model, please contact support to suggest that model be incorporated as an alternative, or, if needed, ask for help implementing it in current software.
There is also some debate as to the best placement of electrodes for measuring impedance through the thorax. See “Where do I place electrodes/sensors/transducers?” for additional discussion.
Page last modified 19Jan2015