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Impedance cardiographic waveforms in children: Involvement in left ventricular ejection time determination during
Eric Wodey1, Lotfi Senhadji, Jean Yves Bansard
1Departments of Anesthesiology and Surgical Intensive Care (Drs. Wodey, Beneux, and Ecoffey) and Physiology (Dr. Carre), Université Rennes, 1, Rennes, France; Laboratoire de Traitement du Signal et de l'Image, Rennes, France (Dr. Senhadji); and Institut National de la Santé et de la Recherche Médicale, Paris, France (Drs. Senhadji, Bansard, and Carre).
Summary
Impedance cardiography (ICG) signal shapes in children do not accurately determine left ventricular ejection time (LVET) or stroke volume. This study highlights limitations in using ICG for hemodynamic monitoring in pediatric critical care.
Area of Science:
- Cardiovascular Physiology
- Biomedical Engineering
- Pediatric Critical Care
Background:
- The physiologic basis of impedance cardiography (ICG) signals remains debated.
- Accurate left ventricular ejection time (LVET) determination is crucial for calculating stroke volume.
- Varied ICG signal morphologies are observed in pediatric patients during anesthesia and critical care.
Purpose of the Study:
- To investigate the relationship between ICG signal shape and echocardiographically derived hemodynamic parameters in children.
- To assess the impact of different ICG signal shapes on the accuracy of LVET determination.
- To explore the utility of ICG for stroke volume calculation in pediatric surgical patients.
Main Methods:
- Prospective study involving 103 pediatric surgical patients (ASA I or II) under general anesthesia.
- Simultaneous recording of electrocardiography, ICG, and Doppler echocardiography.
- Mathematical modeling of ICG signal shape using normalized harmonic amplitudes (NHA) and phase (NHP) analyzed via multiple correspondence analysis.
Main Results:
- ICG-derived LVET showed no significant correlation with Doppler-derived LVET or heart rate.
- NHA and NHP were not significantly related to Doppler-derived LVET or stroke volume.
- NHA demonstrated a link to heart rate and the relative duration of the cardiac diastolic period.
Conclusions:
- The lack of correlation between ICG signal shape variables and Doppler-derived LVET indicates limitations in ICG's accuracy for stroke volume determination in children.
- Arterial compliance may influence ICG signal shape, as suggested by the relationship between NHA, heart rate, and diastolic period length.