title: Clinical validation of cardiac output measurements using femoral artery thermodilution with direct Fick in ventilated children and infants.
abstract: OBJECTIVE
  To validate clinically cardiac output (CO) measurements using femoral artery thermodilution in ventilated children and infants by comparison with CO estimated from the Fick equation via a metabolic monitor.
  
  
  METHODS
  Prospective, comparison study.
  
  
  METHODS
  Paediatric intensive care unit of a university hospital.
  
  
  METHODS
  24 ventilated infants and children, aged 0.3 to 175 months (median age 19 months).
  
  
  METHODS
  Oxygen consumption measurements were made and averaged over a 5-min period, at the end of which arterial and mixed venous blood samples were taken and oxygen saturations measured by co-oximetry, with CO being calculated using the Fick equation. Over this 5-min period, five sets of femoral arterial thermodilution (FATD) measurements were made and averaged. One comparison of CO values was made per patient.
  
  
  RESULTS
  Mean Fick CO was 2.55 l/min (range 0.24 to 8.71 l/min) and mean FATD CO was 2.51 l/min (range 0.28-7.96 l/min). The mean bias was 0.03 l/min (95% confidence interval -0.07 to 0.14 l/min), with limits of agreement of -0.45 to 0.52 l/min. When indexed to body surface area, the mean Fick cardiac index became 3.51 l/min per m2 (1.52-6.98 l/min per m2) and mean FATD 3.49 l/min per m2 (1.74-6.84 l/min per m2). The mean bias was 0.02 l/min per m2 (95% confidence interval -0.11 to 0.15 l/min per m2) with limits of agreement of-0.57 to 0.61 l/min per m2. The mean FATD coefficient of variation was 5.8% (SEM 0.5%).
  
  
  CONCLUSIONS
  FATD compares favourably with Fick derived CO estimates in infants and children and may represent an advance in haemodynamic monitoring of critically ill children.
authors.affiliation: Department of Paediatric Intensive Care, Guy's Hospital, London, UK. s.tibby@umds.ac.uk
authors.forename: S M
authors.initials: SM
authors.lastname: Tibby
authors.forename: M
authors.initials: M
authors.lastname: Hatherill
authors.forename: M J
authors.initials: MJ
authors.lastname: Marsh
authors.forename: G
authors.initials: G
authors.lastname: Morrison
authors.forename: D
authors.initials: D
authors.lastname: Anderson
authors.forename: I A
authors.initials: IA
authors.lastname: Murdoch
mesh_terms: D000293:Adolescent; D002302:Cardiac Output / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D005263:Femoral Artery; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016014:Linear Models; D008991:Monitoring, Physiologic / Q000379:methods*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012121:Respiration, Artificial; D013815:Thermodilution / Q000379:methods*