13 Comparison of Impedance Cardiography to Direct Fick and Echocardiographic Measurement of Cardiac Index in Children.

摘要

BACKGROUND: Impedance cardiography (ICG) provides a continuous, noninvasive measurement of cardiac index (CI) that has been useful in the intensive care setting in adults. However, there is limited data in its application to children. The purpose of this study was to validate a now commercially available ICG system in children.METHODS: Seventeen patients (58% male; mean age 4.2 ± 5.2 years) with biventricular circulation without significant residual shunting were prospectively studied during cardiac catheterization or post-operative recovery in the intensive care unit. Oxygen consumption was measured by indirect calorimetry, while mixed venous and arterial saturations were drawn from existing catheters. Echo measurement of CI was determined by pulsed Doppler and 2-D diameter measurement of the left ventricular outflow tract. Serial ICG and echo CI measurements were performed simultaneously with Fick measurement while the patient was hemodynamically stable.RESULTS: The intraclass correlation coefficient, a measure of reproducibility, for ICG and echo was 0.97 and 0.88, respectively. CI correlation was as follows: Fick vs. ICG (r = 0.82), echo vs. ICG (r = 0.33), and Fick vs. echo (r = 0.34). The mean Fick CI measurement was 3.95+ 1.54 L/min/m2. ICG underestimated Fick and echo CI measurement on average by 1.02+ 0.89 and 0.97+ 1.65 L/min/m2, respectively.CONCLUSIONS: Serial ICG measurements of CI have better reproducibility and better correlation to the direct Fick method when compared to echo measurements in children. In conclusion, ICG is a reliable tool of predicting CI in children with the advantage of being technically easy, continuous, and noninvasive.