title: Bioreactance is not reliable for estimating cardiac output and the effects of passive leg raising in critically ill patients.
abstract: BACKGROUND
  Bioreactance estimates cardiac output in a non-invasive way. We evaluated the ability of a bioreactance device (NICOM®) to estimate cardiac index (CI) and to track relative changes induced by volume expansion.
  
  
  METHODS
  In 48 critically ill patients, we measured CI estimated by the NICOM® device (CINicom) and by transpulmonary thermodilution (CItd, PiCCO2™ device) before and after a 500 ml saline infusion. Before volume expansion, we performed a passive leg raising (PLR) test and measured the changes it induced in CINicom and in pulse contour analysis-derived CI.
  
  
  RESULTS
  Considering the values recorded before PLR and before and after volume expansion (n=144), the bias (lower and upper limits of agreement) between CItd and CINicom was 0.9 (-2.2 to 4.1) litre min(-1) m(-2). The percentage error was 82%. There was no significant correlation between the changes in CItd and CINicom induced by volume expansion (P=0.24). An increase in CI estimated by pulse contour analysis >9% during the PLR test predicted fluid responsiveness with a sensitivity of 84% (95% confidence interval 60-97%) and a specificity of 97% (95% confidence interval 82-100%). The area under the receiver operating characteristic curve constructed to test the ability of the PLR-induced changes in CINicom in predicting fluid responsiveness did not differ significantly from 0.5 (P=0.77).
  
  
  CONCLUSIONS
  The NICOM® device cannot accurately estimate the cardiac output in critically ill patients. Moreover, it could not predict fluid responsiveness through the PLR test.
authors.affiliation: Hôpitaux universitaires Paris-Sud, Hôpital de Bicêtre, service de réanimation médicale, 78, rue du Général Leclerc, F-94270 Le Kremlin-Bicêtre, France.
authors.forename: E
authors.initials: E
authors.lastname: Kupersztych-Hagege
authors.forename: J-L
authors.initials: JL
authors.lastname: Teboul
authors.forename: A
authors.initials: A
authors.lastname: Artigas
authors.forename: A
authors.initials: A
authors.lastname: Talbot
authors.forename: C
authors.initials: C
authors.lastname: Sabatier
authors.forename: C
authors.initials: C
authors.lastname: Richard
authors.forename: X
authors.initials: X
authors.lastname: Monnet
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology*; D003422:Critical Care / Q000379:methods; D005260:Female; D005440:Fluid Therapy; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007866:Leg / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation* / Q000379:methods; D056888:Patient Positioning; D011446:Prospective Studies; D012039:Regional Blood Flow / Q000502:physiology; D012769:Shock / Q000503:physiopathology* / Q000628:therapy; D013815:Thermodilution / Q000379:methods
keywords: equipment, monitors; dobutamine; measurement techniques; measurement, cardiac output; shock