Background. Bioreactance estimates cardiac output in a non-invasive way.We evaluated the ability of a bioreactance device (NICOM®) to estimate cardiac index (CI) and to track relative changes induced by volume expansion. Methods. In 48 critically ill patients,wemeasured CI estimated by the NICOM®device (CINicom) and by transpulmonary thermodilution (CItd, PiCCO2TM device) before and aftera 500 ml saline infusion. Beforevolumeexpansion,weperformedapassiveleg raising (PLR) testandmeasured the changes it induced in CINicom and in pulse contour analysis-derived CI. Results. Considering the values recorded before PLR and before and after volume expansion (n=144), the bias (lower and upper limits of agreement) between CItd and CINicom was 0.9 (-2.2 to 4.1) litre min-1 m-2. The percentage error was 82%. There was no significant correlation between the changes in CItd and CINicom induced by volume expansion (P=0.24). An increase in CI estimated by pulse contour analysis >9% during the PLR test predicted fluid responsiveness with a sensitivity of 84% (95% confidence interval 60-97%) and a specificity of 97% (95% confidence interval 82-100%). The area under the receiver operating characteristic curve constructed to test the ability of the PLR-induced changes in CINicom in predicting fluid responsiveness did not differ significantly from 0.5 (P=0.77). Conclusions. The NICOM® device cannot accurately estimate the cardiac output in critically ill patients. Moreover, it could not predict fluid responsiveness through the PLR test. © The Author . Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved.
- Measurement cardiac output
- Measurement techniques