title: Assessment of cardiac output changes using a modified FloTrac/Vigileo algorithm in cardiac surgery patients.
abstract: BACKGROUND
  The FloTrac/Vigileo (Edwards Lifesciences, Irvine, CA, USA) allows pulse pressure-derived cardiac output measurement without external calibration. Software modifications were performed in order to eliminate initially observed deficits. The aim of this study was to assess changes in cardiac output determined by the FloTrac/Vigileo system (FCO) with an initially released (FCOA) and a modified (FCOB) software version, as well as changes in cardiac output from the PiCCOplus system (PCO; Pulsion Medical Systems, Munich, Germany). Both devices were compared with cardiac output measured by intermittent thermodilution (ICO).
  
  
  METHODS
  Cardiac output measurements were performed in patients after elective cardiac surgery. Two sets of data (A and B) were obtained using FCOA and FCOB in 50 patients. After calibration of the PiCCOplus system, triplicate FCO and PCO values were recorded and ICO was determined in the supine position and cardiac output changes due to body positioning were recorded 15 minutes later (30 degrees head-up, 30 degrees head-down, supine). Student's t test, analysis of variance and Bland-Altman analysis were calculated.
  
  
  RESULTS
  Significant changes of FCO, PCO and ICO induced by body positioning were observed in both data sets. For set A, DeltaFCOA was significantly larger than DeltaICO induced by positioning the head down. For set B, there were no significant differences between DeltaFCOB and DeltaICO. For set A, increased limits of agreement were found for FCOA-ICO when compared with PCO-ICO. For set B, mean bias and limits of agreement were comparable for FCOB-ICO and PCO-ICO.
  
  
  CONCLUSIONS
  The modification of the FloTrac/Vigileo system resulted in an improved performance in order to reliably assess cardiac output and track the related changes in patients after cardiac surgery.
authors.affiliation: Institute of Anaesthesiology and Intensive Care Medicine, Triemli City Hospital Zurich, Birmensdorferstrasse 497, 8063 Zurich, Switzerland.
authors.forename: Alban
authors.initials: A
authors.lastname: Senn
authors.forename: Danny
authors.initials: D
authors.lastname: Button
authors.forename: Andreas
authors.initials: A
authors.lastname: Zollinger
authors.forename: Christoph K
authors.initials: CK
authors.lastname: Hofer
mesh_terms: D000368:Aged; D000465:Algorithms; D002302:Cardiac Output / Q000502:physiology*; D001026:Coronary Artery Bypass; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D012985:Software Design