title: Accuracy of impedance cardiography for evaluating trends in cardiac output: a comparison with oesophageal Doppler.
abstract: BACKGROUND
  Impedance cardiography (ICG) enables continuous, beat-by-beat, non-invasive, operator-independent, and inexpensive cardiac output (CO) monitoring. We compared CO values and variations obtained by ICG (Niccomo™, Medis) and oesophageal Doppler monitoring (ODM) (CardioQ™, Deltex Medical) in surgical patients.
  
  
  METHODS
  This prospective, observational, single-centre study included 32 subjects undergoing surgery with general anaesthesia. CO was measured simultaneously with ICG and ODM before and after events likely to modify CO (vasopressor administration and volume expansion). One hundred and twenty pairs of CO measurements and 94 pairs of CO variation measurements were recorded.
  
  
  RESULTS
  The CO variations measured by ICG correlated with those measured by ODM [r=0.88 (0.82-0.94), P<0.001]. Trending ability was good for a four-quadrant plot analysis with exclusion of the central zone (<10%) [95% confidence interval (CI) for concordance (0.86; 1.00)]. Moderate to good trending ability was observed with a polar plot analysis (angular bias: -7.2°; 95% CI -12.3°; -2.5°; with radial limits of agreement -38°; 24°). After excluding subjects with chronic obstructive pulmonary disease, a Bland-Altman plot showed a mean bias of 0.47 litre min(-1), limits of agreements between -1.24 and 2.11 litre min(-1), and a percentage error of 35%.
  
  
  CONCLUSIONS
  ICG appears to be a reliable method for the non-invasive monitoring of CO in patients undergoing general surgery.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine and INSERM U1088, Jules Verne University of Picardy, Amiens, France lorne.emmanuel@chu-amiens.fr.
authors.forename: E
authors.initials: E
authors.lastname: Lorne
authors.affiliation: Department of Anesthesiology and Critical Care Medicine and INSERM U1088, Jules Verne University of Picardy, Amiens, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Mahjoub
authors.affiliation: Biostatistics Department, Amiens University Medical Center, Amiens, France.
authors.forename: M
authors.initials: M
authors.lastname: Diouf
authors.affiliation: Department of Anesthesiology and Critical Care Medicine and.
authors.forename: J
authors.initials: J
authors.lastname: Sleghem
authors.affiliation: Department of Anesthesiology and Critical Care Medicine and.
authors.forename: C
authors.initials: C
authors.lastname: Buchalet
authors.affiliation: Department of Anesthesiology and Critical Care Medicine and.
authors.forename: P-G
authors.initials: PG
authors.lastname: Guinot
authors.affiliation: Department of Anesthesiology and Critical Care Medicine and.
authors.forename: S
authors.initials: S
authors.lastname: Petiot
authors.affiliation: Department of Anesthesiology and Critical Care Medicine and.
authors.forename: A
authors.initials: A
authors.lastname: Kessavane
authors.affiliation: Department of Anesthesiology and Critical Care Medicine and.
authors.forename: B
authors.initials: B
authors.lastname: Dehedin
authors.affiliation: Department of Anesthesiology and Critical Care Medicine and INSERM U1088, Jules Verne University of Picardy, Amiens, France.
authors.forename: H
authors.initials: H
authors.lastname: Dupont
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000768:Anesthesia, General; D002302:Cardiac Output / Q000502:physiology*; D002307:Cardiography, Impedance / Q000379:methods*; D016001:Confidence Intervals; D003627:Data Interpretation, Statistical; D017548:Echocardiography, Transesophageal / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D010092:Oximetry; D011446:Prospective Studies; D015203:Reproducibility of Results; D018401:Sample Size
keywords: cardiopulmonary, monitoring; monitoring; ultrasound