title: A comparison of cardiac output by thoracic impedance and direct fick in children with congenital heart disease undergoing diagnostic cardiac catheterization.
abstract: OBJECTIVE
  To evaluate the measurement of cardiac output (CO) using continuous electrical bioimpedance cardiography (Physioflow; Neumedx, Philadelphia, PA) (CO(PF)) with a simultaneous direct Fick measurement (CO(FICK)) in children with congenital heart disease.
  
  
  METHODS
  A prospective cohort study comparing 2 methods of measurement of CO.
  
  
  METHODS
  A quaternary university-affiliated pediatric hospital.
  
  
  METHODS
  Children undergoing cardiac catheterization for clinical care.
  
  
  METHODS
  The Physioflow measured continuous real time CO in 15-second epochs and simultaneous measurement of cardiac output by direct Fick (with mass spectrometry to assess VO(2)) were acquired.
  
  
  RESULTS
  Sixty-five patients were recruited, and data from 56 (25 males) were adequate for analysis. The median age at study was 3.5 years (range, 0.4-16.6 years), and the median body surface area was 0.62 m(2) (range, 0.31-1.71). There were 25 of 56 (45%) with univentricular physiology. A total of 19,228 Physioflow data points were available for the analysis of which 14,569 (76%) were valid; 96% of the invalid measurements were identified as artifacts by the device. The average cardiac index of valid measurements was 3.09 ± 0.72 L/min/m(2). Compared with the Fick CO, the mean bias was -0.09 L/min, but the 95% limits of agreement were -3.20 to +3.01 L/min/m(2). Consequently, only 20 of 56 (36%) of measurements were within 20%, and 31 of 56 (55%) of measurements were within 30% of each other.
  
  
  CONCLUSIONS
  Compared with measurements made by direct Fick, CO measured using the Physioflow device was unreliable in anesthetized children with congenital heart disease.
authors.affiliation: Department of Anesthesia, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Katherine
authors.initials: K
authors.lastname: Taylor
authors.forename: Gustavo
authors.initials: G
authors.lastname: La Rotta
authors.forename: Brian W
authors.initials: BW
authors.lastname: McCrindle
authors.forename: Cedric
authors.initials: C
authors.lastname: Manlhiot
authors.forename: Andrew
authors.initials: A
authors.lastname: Redington
authors.forename: Helen
authors.initials: H
authors.lastname: Holtby
mesh_terms: D000293:Adolescent; D016477:Artifacts; D001784:Blood Gas Analysis; D002138:Calibration; D006328:Cardiac Catheterization / Q000379:methods*; D002302:Cardiac Output / Q000502:physiology*; D002307:Cardiography, Impedance / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D005260:Female; D018729:Fontan Procedure; D006330:Heart Defects, Congenital / Q000175:diagnosis* / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007223:Infant; D008297:Male; D013058:Mass Spectrometry; D010100:Oxygen / Q000032:analysis; D010101:Oxygen Consumption / Q000502:physiology; D013318:Stroke Volume / Q000502:physiology
chemical_list: D010100:Oxygen