title: Non-invasive cardiac output by transthoracic electrical bioimpedence in post-cardiac surgery patients: comparison with thermodilution method.
abstract: OBJECTIVE
  Thoracic electrical bioimpedance (TEB) cardiac output (CO) is being explored increasingly as a non-invasive alternative to the pulmonary artery catheter (PAC). This study compared TEB-CO measured using a new instrument--NICOMON (Larsen & Toubro Ltd. India) with thermodilution (Td) CO in post-cardiac surgery patients.
  
  
  METHODS
  Postoperative cardiac surgical patients requiring a PAC for their management were studied. TEB-CO was measured by passing a 4 mA RMS alternating current across the chest and measuring the analog bioimpedence across the thorax. Kubicek equation was used to estimate TEB-CO. Td-CO was measured using a PAC. Bland-Altman analysis was used to compare paired data.
  
  
  RESULTS
  One hundred and ninety-seven pairs of CO measurements were made by the two methods among 35 patients. Mean TEB-CO was 5.15 +/- 1.27 l/min and mean Td-CO was 5.22 +/- 1.28 l/min. Pearson correlation coefficient (r) for these measurements was 0.856 (P < 0.01), with bias -0.0651 l and precision: +/-1.37 l/min. The percentage error of measurement of this precision was 26.44%. Cardiac index also correlated among the two methods (r = 0.789; P = 0.01).
  
  
  CONCLUSIONS
  Thoracic electrical bioimpedance cardiac output compares favorably with thermodilution method among post-cardiac surgery patients. Further studies are indi- cated with this instrument to validate its efficacy in various clinical situations and utility in monitoring hemodynamic interventions.
authors.affiliation: Department of Neurology, National Institute of Mental Health & Neurosciences, Hosur Road, Bangalore, 560029, India. grarunoday@yahoo.co.in
authors.forename: Arunodaya R
authors.initials: AR
authors.lastname: Gujjar
authors.forename: K
authors.initials: K
authors.lastname: Muralidhar
authors.forename: Sanjay
authors.initials: S
authors.lastname: Banakal
authors.forename: Ratan
authors.initials: R
authors.lastname: Gupta
authors.forename: Talakad N
authors.initials: TN
authors.lastname: Sathyaprabha
authors.forename: P S
authors.initials: PS
authors.lastname: Jairaj
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002302:Cardiac Output; D002307:Cardiography, Impedance / Q000379:methods*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D005260:Female; D006331:Heart Diseases / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011182:Postoperative Care / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013815:Thermodilution / Q000379:methods*; D055815:Young Adult