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Comparative Study
Five algorithms that calculate cardiac output from the arterial waveform: a comparison with Doppler ultrasound.
- J Zhang, L A H Critchley, and L Huang.
- Department of Anesthesiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
- Br J Anaesth. 2015 Sep 1;115(3):392-402.
BackgroundDifferent mathematical approaches are used to calculate arterial pulse pressure wave analysis (PPWA) cardiac output. The CardioQ-Combi is a research oesophageal Doppler (COODM) monitor that includes these five fundamental PPWA algorithms. We compared these PPWA cardiac output readings to COODM and suprasternal USCOM Doppler (COUS) over a range of cardiac output values induced by dopamine infusion in patients undergoing major surgery. USCOM acted as a control.MethodsSerial sets of cardiac output data were recorded at regular intervals as cardiac output increased. Formulae included: cardiac output calculated form systemic vascular resistance (COMAP), pulse pressure (COPP), Liljestrand-Zander formula (COLZ), alternating current power (COAC) and systolic area with Kouchoukos correction (COSA). The reference method for comparisons was COODM. Statistical methods included: Scatter plots (correlation), Bland-Altman (agreement) and concordance (trending) and polar (trending).ResultsFrom 20 patients 255 sets of cardiac output comparative data were collected. Mean cardiac output for each method ranged between 5.0 and 5.5 litre min(-1). For comparisons between COUS and the five PPWA algorithms with COODM: Correlation was best with COUS (R(2)=0.81) followed by COLZ (R(2)=0.72). Bias ranged between 0.1 and 0.5 litre min(-1). Percentage error was lowest with COUS (26.4%) followed by COLZ (35.2%), others (40.7 to 56.3%). Concordance was best with COUS (92%), followed by COLZ (71%), others (64 to 66%). Polar analysis (mean(standard deviation)) were best with COUS (-2.7 (21.1)), followed by COLZ (+4.7 (26.6).ConclusionsThe Liljestrand-Zander PPWA formula was most reliable compared with oesophageal Doppler in major surgical patients under general anaesthesia, but not better than USCOM.© The Author 2015. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
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