Non-invasive assessment of gestational hemodynamics: benefits and limitations of impedance cardiography versus other techniques

Abstract

To obtain data for maternal stroke volume and cardiac output during pregnancy, it is preferable to use a non-invasive, accurate and reproducible method. In this aspect, impedance cardiography is an excellent technique which is also highly accessible and easy to perform. This paper is a comprehensive review on the published literature about impedance cardiography and highlights the strengths and limitations of its applications in obstetrics.

Keywords::

• bioimpedance
• hemodynamics
• impedance cardiography
• non-invasive
• obstetrics
• pregnancy

Financial & competing interests disclosure

This study is part of the Limburg Clinical Research Program (LCRP) UHasselt-ZOL-Jessa, supported by the foundation Limburg Sterk Merk, Hasselt University, Ziekenhuis Oost-Limburg and Jessa Hospital. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• • The impedance cardiography (ICG) device has been developed by Kubicek et al. in 1966. Ever since, the equation has been adapted and improved several times.

• • The ICG device detects pulse-synchronic changes in thoracic electrical bioimpedance between simple surface electrodes, together with a conventional ECG.

• • Compared with invasive procedures, ICG has a non-invasive nature with a low-risk and low-cost profile. For these reasons, ICG is preferable over invasive procedures for application in non-critically ill subjects and pregnant women.

• • The overall correlation between ICG and the currently known invasive techniques is around 0.80, however there still is some disagreement about the reliability of the impedance technique.

• • Most papers report an overestimation of the stroke volume measured by ICG.

• • ICG is less reliable during exercises.

• • ICG can be used in women with an uncomplicated and complicated pregnancy, as measurements seemed reliable.

• • The results of ICG in edematous patients should be interpreted with care.

Notes