title: Cardiac output derived from arterial pressure waveform analysis in patients undergoing cardiac surgery: validity of a second generation device.
abstract: BACKGROUND
  The performance of a recently introduced, arterial waveform-based device for measuring cardiac output (CO) without the need of invasive calibration (FloTrac/Vigileo) has been controversial. We designed the present study to assess the validity of an improved version of this monitoring technique compared with intermittent thermodilution CO measurement using a pulmonary artery catheter in patients undergoing cardiac surgery.
  
  
  METHODS
  Forty ASA III patients scheduled for elective coronary artery bypass grafting with cardiopulmonary bypass (CPB) were studied. Simultaneous CO measurements by bolus thermodilution and the FloTrac/Vigileo device were obtained after induction of anesthesia (T1), before CPB (T2), after CPB (T3), after sternal closure (T4), on arrival in the intensive care unit (T5), 4 h (T6), 8 h (T7), and 24 h after surgery (T8). CO was indexed to the body surface area (cardiac index, CI). A percentage error of 30% or less was established as the criterion for method interchangeability.
  
  
  RESULTS
  Two hundred and eighty-two data pairs were analyzed. Thermodilution CI ranged from 1.2 to 4.1 L x min(-1) x m(-2) (mean 2.5 +/- 0.54 L x min(-1) x m(-2)). Bias and precision (1.96 sd of the bias) were 0.19 L x min(-1) x m(-2) and +/- 0.60 L x min(-1) x m(-2), resulting in an overall percentage error of 24.6%. Subgroup analysis revealed a percentage error of 28.3% for data pairs obtained intraoperatively (T1-4) and 20.7% in intensive care unit (T5-8).
  
  
  CONCLUSIONS
  CI values obtained by the improved, second generation semiinvasive arterial waveform device showed good intraoperative and postoperative agreement with intermittent pulmonary artery thermodilution CI measurements in patients undergoing coronary artery bypass graft surgery.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, Klinikum Ludwigshafen, Bremserstr. 79, 67063 Ludwigshafen, Germany. j-mayer@gmx.de
authors.forename: Jochen
authors.initials: J
authors.lastname: Mayer
authors.forename: Joachim
authors.initials: J
authors.lastname: Boldt
authors.forename: Michael W
authors.initials: MW
authors.lastname: Wolf
authors.forename: Johannes
authors.initials: J
authors.lastname: Lang
authors.forename: Stefan
authors.initials: S
authors.lastname: Suttner
mesh_terms: D000368:Aged; D001794:Blood Pressure; D001830:Body Surface Area; D002302:Cardiac Output; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D003324:Coronary Artery Disease / Q000503:physiopathology* / Q000601:surgery; D004867:Equipment Design; D005260:Female; D006334:Heart Function Tests / Q000295:instrumentation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000503:physiopathology; D017534:Radial Artery / Q000503:physiopathology; D015203:Reproducibility of Results; D013815:Thermodilution; D013997:Time Factors