Key result
Impedance cardiography showed acceptable agreement with echocardiography for measuring cardiac output in atrial fibrillation (4.77 vs 4.93 L/min), and was superior to inert gas rebreathing.
Why the study?
Do inert gas rebreathing and impedance cardiography accurately measure cardiac output compared to echocardiography in patients with atrial fibrillation?
Cross-Sectional (n=151)
Do inert gas rebreathing and impedance cardiography accurately measure cardiac output compared to echocardiography in patients with atrial fibrillation?
Impedance cardiography is superior to inert gas rebreathing for non-invasive measurement of cardiac output in patients with atrial fibrillation, demonstrating acceptable agreement with echocardiography.
Answers are grounded in this paper and cite their sources.
Impedance cardiography may aid non-invasive cardiac output assessment in atrial fibrillation; leaves open prospective validation against echocardiography.
BACKGROUND: Atrial fibrillation (AF) is associated with significant morbidity and mortality. To test the effect of interventions, knowledge of cardiac output (CO) is important. However, the irregular heart rate might cause some methods for determination of CO to have inherent weaknesses. Objective. To assess the validity of these methods in AF, a new inert gas rebreathing device and impedance cardiography was tested with echocardiography as reference. METHODS: Using a cross-sectional design, 127 patients with AF and 24 in SR were consecutively recruited. Resting CO was measured using inert gas rebreathing (n = 62) or impedance measurement of intrathoracic blood flow (n = 89) in separate studies with echocardiographic measurement as reference. RESULTS: CO determined with impedance cardiography was mean 4.77 L/min ± 2.24(SD) compared to 4.93 L/min ± 1.17 by echocardiography (n = 89, n.s.) in patients with AF. CO by inert gas rebreathing was 4.98 L/min ± 2.49(SD) compared to 5.70 L/min ± 2.49 by echocardiography (n = 62, n.s.) in patients with AF and SR (AF 5.42 ± 2.9 vs. 6.27, n.s. and SR 4.09 ± 1.08 vs. 4.35 ± 0.86, n.s.). Mean bias between impedance cardiography and echocardiography was 0.14 ± 0.95 L/min and -0.13 ± 0.98 L/min between inert gas rebreathing and echocardiography. Inert gas rebreathing showed larger intra-patient variation than impedance cardiography (0.11 vs. 0.054). Correlation between inert gas rebreathing and echocardiography was r = -0.060 and between impedance cardiography and echocardiography was r = 0.128. Impedance cardiography and inert gas rebreathing both underestimated CO compared to echocardiography. CONCLUSION: Variation between the inert gas rebreathing and the reference method for AF patients was less than desired. Impedance cardiography was superior to inert gas rebreathing and showed acceptable agreement with echocardiography and variability similar to echocardiography.
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Osbak et al. (2011) conducted a cross-sectional in Atrial fibrillation (n=151). Impedance cardiography and inert gas rebreathing vs. Echocardiography was evaluated on Resting cardiac output (Mean bias 0.14 L/min, p=n.s.). Impedance cardiography showed acceptable agreement with echocardiography for measuring cardiac output in atrial fibrillation (4.77 vs 4.93 L/min), and was superior to inert gas rebreathing.
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