title: Determination of cardiac output by ultrasound dilution technique in infants and children: a validation study against direct Fick principle.
abstract: BACKGROUND
  In critically ill children, monitoring of cardiac output (CO) is essential to guide haemodynamic management and facilitate cardiovascular therapy. The ultrasound dilution technique (UDT), a novel minimally invasive indicator method, was recently introduced to determine CO. We validated UDT against the 'gold standard' reference technique, the direct Fick principle, in infants and children.
  
  
  METHODS
  Twenty-six children (median age: 6 yr 2 months; median weight: 19.2 kg) underwent diagnostic heart catheterization. In each child, CO was determined by the Fick principle using direct measurement of oxygen consumption and invasive oximetry. Consecutively, haemodynamically stable conditions provided; three independent measurements of CO were conducted with UDT. CO values were compared using bias and limits of agreement calculated using the Bland-Altman approach and linear regression analysis for the complete study group and for a subgroup with body weight <20 kg (n=14).
  
  
  RESULTS
  The mean (standard deviation) CO values were 3.76 (1.73) litre min(-1) (range 1.38-6.97) for the direct Fick principle and 3.49 (1.72) litre min(-1) (range 1.31-7.00) for UDT. An excellent correlation (r=0.96) was found between both methods (P<0.0001). The Bland-Altman analysis demonstrated good clinical agreement with a mean bias of 0.26 litre min(-1), limits of agreement of -0.66 and 1.19 litre min(-1), and percentage error of 25.9%. Comparable results were obtained for patients <20 kg (mean bias=0.19 litre min(-1), percentage error=25.5%).
  
  
  CONCLUSIONS
  CO measurements by UDT agree favourably with Fick-derived CO data and both techniques were found to be equivalent and interchangeable. UDT represents a valid and applicable method for repetitive CO determinations in infants and children.
authors: Department of Paediatric Cardiology and Intensive Care Medicine, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany.
authors: M
authors: M
authors: Boehne
authors: M
authors: M
authors: Baustert
authors: V
authors: V
authors: Paetzel
authors: H
authors: H
authors: Köditz
authors: S
authors: S
authors: Schoof
authors: C M
authors: CM
authors: Happel
authors: H
authors: H
authors: Bertram
mesh_terms: D000293:Adolescent; D000465:Algorithms; D002153:Calorimetry, Indirect; D006328:Cardiac Catheterization; D002302:Cardiac Output / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006330:Heart Defects, Congenital / Q000503:physiopathology; D006801:Humans; D007201:Indicator Dilution Techniques; D007223:Infant; D008297:Male; D010092:Oximetry; D010101:Oxygen Consumption / Q000502:physiology; D011446:Prospective Studies; D012121:Respiration, Artificial; D014463:Ultrasonography / Q000379:methods*
keywords: cardiac output; children; direct Fick principle; ultrasound dilution technique