title: Measurement of cardiac output with non-invasive Aesculon impedance versus thermodilution.
abstract: BACKGROUND
  This study compared the non-invasive thoracic electrical bioimpedance Aesculon technique (TEB(Aesculon) ) with thermodilution (TD) to evaluate whether TEB(Aesculon) may offer a reliable means for estimating cardiac output (CO) in humans.
  
  
  METHODS
  Cardiac output was measured with TD and TEB(Aesculon) in 33 patients, with a mean age ± SEM of 59 ± 2·7 years, that underwent right heart catheterization for clinical investigation of pulmonary hypertension or severe heart failure. Four to five CO measurements were performed with each technique simultaneously in 33 patients at rest, 11 during exercise and seven during NO inhalation.
  
  
  RESULTS
  Cardiac output correlated poorly between TEB(Aesculon) and TD at rest (r = 0·46, P<0·001), during exercise (r = 0·35, P<0·013) and NO inhalation (r = 0·41, P<0·017). CO was higher for TEB(Aesculon) than TD with 0·86 ± 0·14 l min(-1) at rest (P<0·001) and 2·95 ± 0·69 l min(-1) during exercise (P< 0·003), but similar during NO inhalation, with a tendency (P< 0·079) to be 0·44 ± 0·19 l min(-1) higher for TEB(Aesculon) than TD. CO increased from rest to exercise for TEB(Aesculon) and TD with 6·11 ± 0·6 l min(-1) (P<0·001) and 3·91 ± 0·36 l min(-1) (P<0·001), respectively; an increase that was higher (P<0·002) for TEB(Aesculon) than TD. During NO inhalation, compared to rest, CO decreased for TEB(Aesculon) with 0·62 ± 0·11 l min(-1) (P<0·002), but not significantly for TD with 0·21 ± 0·12 l min(-1) (P<0·11). Bland-Altman analysis showed a poor agreement between TEB(Aesculon) and TD.
  
  
  CONCLUSIONS
  TEB(Aesculon) overestimated CO compared to TD with ∼17% at rest and ∼34% during exercise, but the techniques showed similar results during NO inhalation. CO, furthermore, correlated poorly between TEB(Aesculon) and TD. TEB(Aesculon) may at present not replace TD for reliable CO measurements in humans.
authors.affiliation: GoRadLab, The Öresund Cardiovascular Research Collaboration, The Clinic for heart Failure and valvular heart disease, Department of Cardiology, Lund University and Skåne University Hospital, Sweden. petter.hedelin@gmail.com
authors.forename: Hedelin
authors.initials: H
authors.lastname: Petter
authors.forename: Agger
authors.initials: A
authors.lastname: Erik
authors.forename: Ekmehag
authors.initials: E
authors.lastname: Björn
authors.forename: Rådegran
authors.initials: R
authors.lastname: Göran
mesh_terms: D000280:Administration, Inhalation; D006328:Cardiac Catheterization / Q000379:methods; D002302:Cardiac Output / Q000502:physiology*; D002307:Cardiography, Impedance / Q000379:methods*; D015444:Exercise / Q000502:physiology; D005260:Female; D006333:Heart Failure / Q000175:diagnosis; D006801:Humans; D006976:Hypertension, Pulmonary / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000008:administration & dosage; D012146:Rest / Q000502:physiology; D016683:Supine Position / Q000502:physiology; D013815:Thermodilution / Q000379:methods*
chemical_list: D009569:Nitric Oxide