title: Noninvasive assessment of cardiac output using thoracic electrical bioimpedance in hemodynamically stable and unstable patients after cardiac surgery: a comparison with pulmonary artery thermodilution.
abstract: OBJECTIVE
  To compare noninvasive cardiac output (CO)measurement obtained with a new thoracic electrical bioimpedance (TEB) device, using a proprietary modification of the impedance equation, with invasive measurement obtained via pulmonary artery thermodilution.
  
  
  METHODS
  Prospective, observational study.
  
  
  METHODS
  Surgical intensive care unit (ICU) of a university-affiliated community hospital.
  
  
  METHODS
  Seventy-four adult patients undergoing elective cardiac surgery with routine pulmonary artery catheter placement.
  
  
  METHODS
  None.
  
  
  RESULTS
  Simultaneous paired CO and cardiac index (CI) measurements by TEB and thermodilution were obtained in mechanically ventilated patients upon admission to the ICU. For analysis of CI data the patients were subdivided into a hemodynamically stable group and a hemodynamically unstable group. The groups were analyzed using linear regression and tests of bias and precision. We found a significant correlation between thermodilution and TEB (r = 0.83; n < 0.001), accompanied by a bias of -0.01 l/min/m(2) and a precision of +/-0.57 l/min/m(2) for all CI data pairs. Correlation, bias, and precision were not influenced by stratification of the data. The correlation coefficient, bias, and precision for CI were 0.86 (n< 0.001), 0.03 l/min/m(2), and +/-0.47 l/min/m(2) in hemodynamically stable patients and 0.79 (n< 0.001), 0.06 l/min/m(2), and +/-0.68 l/min/m(2) in hemodynamically unstable patients.
  
  
  CONCLUSIONS
  Our results demonstrate a close correlation and clinically acceptable agreement and precision between CO measurements obtained with impedance cardiography using a new algorithm to calculate CO from variations in TEB, and those obtained with the clinical standard of care, pulmonary artery thermodilution, in hemodynamically stable and unstable patients after cardiac surgery.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, Klinikum der Stadt Ludwigshafen, Bremser Strasse 79, Ludwigshafen, Germany. suttner@gmx.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Suttner
authors.forename: Thilo
authors.initials: T
authors.lastname: Schöllhorn
authors.forename: Joachim
authors.initials: J
authors.lastname: Boldt
authors.forename: Jochen
authors.initials: J
authors.lastname: Mayer
authors.forename: Kerstin D
authors.initials: KD
authors.lastname: Röhm
authors.forename: Katrin
authors.initials: K
authors.lastname: Lang
authors.forename: Swen N
authors.initials: SN
authors.lastname: Piper
mesh_terms: D000368:Aged; D002302:Cardiac Output; D006348:Cardiac Surgical Procedures; D002407:Catheterization, Swan-Ganz; D017097:Electric Impedance; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods*; D011184:Postoperative Period; D013815:Thermodilution / Q000379:methods*