title: Electrical velocimetry as a tool for measuring cardiac output in small infants after heart surgery.
abstract: OBJECTIVE
  Cardiac output (CO), the product of stroke volume (SV) and heart rate, is essential to guarantee organ perfusion, especially in the intensive care setting. As invasive measurement of CO bears the risk of complications there is a need for non-invasive alternatives. We investigated if electrical velocimetry (EV) and transthoracic Doppler (Doppler-TTE) are interchangeable for the non-invasive measurement of SV and able to reflect the post-surgical SV/CO trend.
  
  
  METHODS
  Comparison of SV measurements by EV and Doppler-TTE was performed in 24 newborns after switch operation (n = 240 measurements). Three subgroups of measurements (=periods) were created according to the patients' status in the course of post-surgical CO recovery.
  
  
  RESULTS
  Bland-Altman analysis found acceptable bias and limits of agreement for the interchangeability of the two methods. Mean overall SV was 3.7 ml with a mean overall bias of 0.28 ml (=7.6 %). The mean percentage error of 29 % was acceptable according to the method of Critchley and Critchley. Overall precision expressed by the coefficient of variation (CV) was 6.6 % for SV(TTE) and 4.4 % for SV(EV). SV(TTE) and SV(EV) medians in the three periods were significantly different and documented the post-surgical CO trend.
  
  
  CONCLUSIONS
  EV and Doppler-TTE are interchangeable for estimating SV. EV has the advantages of easy handling and allows continuous measurement.
authors.affiliation: Department of Pediatric Cardiac Intensive Care, Centre Chirurgical Marie Lannelongue, INSERM 999, University Paris Sud, 133, Avenue de Résistance, 92350 Le Plessis Robinson, France. osgro@aol.com
authors.forename: Oswin
authors.initials: O
authors.lastname: Grollmuss
authors.forename: Serge
authors.initials: S
authors.lastname: Demontoux
authors.forename: André
authors.initials: A
authors.lastname: Capderou
authors.forename: Alain
authors.initials: A
authors.lastname: Serraf
authors.forename: Emre
authors.initials: E
authors.lastname: Belli
mesh_terms: D000465:Algorithms; D015150:Echocardiography, Doppler; D006801:Humans; D007231:Infant, Newborn; D011184:Postoperative Period; D011446:Prospective Studies; D012212:Rheology / Q000379:methods*; D013318:Stroke Volume / Q000502:physiology*; D013903:Thoracic Surgery