title: Evaluation of impedance cardiography: comparison of NCCOM3-R7 with Fick and thermodilution methods.
abstract: OBJECTIVE
  To assess the degree of error of the BoMed NCCOM3 model revision seven (R7) impedance cardiograph in determining stroke volume and estimated cardiac output.
  
  
  METHODS
  Three-group, within-subject, repeated measures design.
  
  
  METHODS
  Group 1: patients (n = 17) with heart disease undergoing an elective coronary angiogram; group 2: patients (n = 28) after elective heart surgery; and group 3: healthy volunteers (n = 28).
  
  
  METHODS
  Cardiac output was determined by the BoMed NCCOM3-R7 impedance cardiograph, Fick principle, and thermodilution method. The NCCOM3-R7 was compared with the direct Fick and thermodilution methods in groups 1 and 2, respectively, to estimate validity coefficients. In group 3, repeated measures were obtained with the NCCOM3-R7 to calculate reliability coefficients.
  
  
  RESULTS
  The NCCOM3-R7 underestimated Fick measurements by 1.050 +/- 1.529 L/min at rest and 1.505 +/- 2.214 L/min during exercise. Correlation coefficients of 0.684 at rest (p = 0.001) and 0.219 during exercise (p = 0.248) were obtained. The NCCOM3-R7 underestimated thermodilution values by 0.425 +/- 1.325 L/min in subjects initially after heart surgery and 0.358 +/- 1.235 L/min 2 to 4 hours later. Correlation coefficients of 0.547 (p = 0.002) and 0.505 (p = 0.004) were obtained for the two time periods, respectively. A reliability coefficient of 0.837 was calculated with healthy subjects.
  
  
  CONCLUSIONS
  The NCCOM3-R7 has a clinically unacceptable level of error for evaluating cardiac performance in patients with heart disease.
authors.affiliation: Critical Care Nursing Program, Misericordia Hospital, Edmonton, Alberta, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Yakimets
authors.forename: L
authors.initials: L
authors.lastname: Jensen
mesh_terms: D000328:Adult; D000368:Aged; D002302:Cardiac Output; D006348:Cardiac Surgical Procedures; D002307:Cardiography, Impedance / Q000379:methods*; D003951:Diagnostic Errors; D015444:Exercise; D005260:Female; D006331:Heart Diseases / Q000503:physiopathology; D006801:Humans; D007201:Indicator Dilution Techniques; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D015203:Reproducibility of Results; D012146:Rest; D013815:Thermodilution