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Erschienen in:
01.10.2011 | Original Paper
A comparative evaluation of electrical velocimetry and inert gas rebreathing for the non-invasive assessment of cardiac output
Erschienen in: Clinical Research in Cardiology | Ausgabe 10/2011
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Background
When assessing the function of the cardiovascular system, cardiac output (CO) is a substantial parameter. For its determination, numerous non-invasive techniques have been proposed in the recent years including inert gas rebreathing (IGR) and impedance cardiography (ICG). The aim of our study was to evaluate whether a novel ICG algorithm (electrical velocimetry) and IGR can be used interchangeably in the clinical setting.
Methods
A total of 120 consecutive stable patients were included resulting in two pairs of repeated non-invasive cardiac output measurements.
Results
The mean CO was 5.0 ± 1.2 l/min (range 2.6–8.6 l/min) using IGR and 4.4 ± 1.1 l/min (1.7–7.4 l/min) using ICG, respectively. Bland–Altman analysis revealed an acceptable agreement with a mean bias of 0.6 ± 1.2 l/min. We found a high reproducibility with a mean bias of 0.2 ± 0.7 l/min for IGR and 0.0 ± 0.3 l/min for ICG (p < 0.001), respectively. There was a statistically significant difference for unphysiological circulatory conditions represented by values of 2.6–4.1 l/min and 5.6–8.6 l/min.
Conclusions
Both non-invasive techniques are associated with low operating costs and require only a few expendable items for the rapid determination of cardiac function. We found an acceptable agreement between IGR and ICG as well as a high reproducibility, which was statistically significant higher for ICG. For cardiac output states exceeding the physiological range, we found a statistically significant difference. Consequently, values of cardiac function determined by either method should not be used interchangeably in the clinical setting.