title: Comparison of electrical velocimetry and thermodilution techniques for the measurement of cardiac output.
abstract: OBJECTIVE
  To compare a new method of non-invasive determination of cardiac output based on electrical velocimetry (EV-CO) with invasive thermodilution methods.
  
  
  METHODS
  Fifty critically ill patients were enrolled into the study. EV-CO was compared with cardiac output measured by a pulmonary artery catheter (PA-CO) in one group (n= 25) and by a femoral artery catheter (PiCCO-CO) in a second group (n= 25), by simultaneous measurements. Standard electrocardiography electrodes were used for non-invasive measurements, and EV-CO was calculated using the Bernstein-Osypka equation. The invasive measurements of PA-CO and PiCCO-CO were made by the injection of iced 0.9% saline and the recording of thermodilution curves.
  
  
  RESULTS
  The precision values of EV-CO, PA-CO and PiCCO-CO measurements were +/- 0.46 [95% confidence interval (95% CI), +/- 0.06], +/- 0.57 (95% CI, +/- 0.09) and +/- 0.48 l/min (95% CI, +/- 0.08 l/min), respectively. The mean differences between EV-CO and PA-CO or PiCCO-CO were -0.05 +/- 0.71 and 0.22 +/- 0.78 l/min, respectively. The lower and upper limits of agreement for the comparison of EV-CO with PA-CO were -1.47 and 1.37 l/min (95% CI, +/- 0.25 l/min), respectively. In the comparison of EV-CO and PiCCO-CO, lower and upper limits of -1.34 and 1.78 l/min (95% CI, +/- 0.27 l/min) were found. The percentage errors between EV-CO and PA-CO or PiCCO-CO were 26.5% and 26.4%, respectively.
  
  
  CONCLUSIONS
  The values of cardiac output were statistically comparable between the groups. Therefore, electrical velocimetry is a suitable method to evaluate haemodynamic variables with clinically acceptable accuracy.
authors.affiliation: Department of Intensive Care Medicine, University Hospital RWTH Aachen, Aaschen, Germany. nzoremba@ukaachen.de
authors.forename: N
authors.initials: N
authors.lastname: Zoremba
authors.forename: J
authors.initials: J
authors.lastname: Bickenbach
authors.forename: B
authors.initials: B
authors.lastname: Krauss
authors.forename: R
authors.initials: R
authors.lastname: Rossaint
authors.forename: R
authors.initials: R
authors.lastname: Kuhlen
authors.forename: G
authors.initials: G
authors.lastname: Schälte
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D002248:Carbon Monoxide / Q000097:blood; D002302:Cardiac Output / Q000502:physiology*; D004560:Electricity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013815:Thermodilution / Q000379:methods*
chemical_list: D002248:Carbon Monoxide