title: The relation between inferior vena cava oxygen saturation, superior vena cava flow, fractional oxygen extraction and haemoglobin affinity in sick newborns: a pilot study.
abstract: OBJECTIVE
  To determine whether inferior vena cava oxygen saturation (UvO2) or lower-body fractional oxygen extraction (FOE) could detect poor cardiac output in newborns.
  
  
  METHODS
  UvO2 and arterial oxygen saturation (SaO2) were measured simultaneously with echocardiographic determination of superior vena cava blood flow (SVC flow) at <12, 12-24 and >24 h. Haemoglobin concentration ([Hb]), haemoglobin oxygen affinity (HOA) and lactate were measured and FOE calculated.
  
  
  RESULTS
  56 studies in 17 infants, gestational age (median (range)) 26 wk 4 d (23 wk 2 d-42 wk 3 d): UvO2 (mean (SD)) was 84.9% (5.0), 77.6% (9.2) and 81.7% (12.9) at <12, 12-24 and >24 h, respectively; SVC flow (mean (SD)) increased from 71.7 (33) to 85 (66) and 123 (88) ml/kg/min at <12, 12-24 and >24 h, respectively. Despite a fall in mean [Hb], mean upper-body oxygen delivery increased due to increases in both SVC flow and arteriovenous content difference. There was a negative correlation between [Hb] and FOE. Infants with high HOA had significantly lower FOE.
  
  
  CONCLUSIONS
  Measurement of UvO2 is feasible in newborns. Changes to SVC flow and arteriovenous content difference lead to improvements in oxygen delivery. The interaction of HOA warrants further study.
authors.affiliation: Department of Paediatrics, Mercy Hospital for Women, East Melbourne, Australia.
authors.forename: James
authors.initials: J
authors.lastname: Hart
authors.forename: Prakash
authors.initials: P
authors.lastname: Vemgal
authors.forename: Sandra
authors.initials: S
authors.lastname: Cocks-Drew
authors.forename: Catherine
authors.initials: C
authors.lastname: Harrison
authors.forename: Chad
authors.initials: C
authors.lastname: Andersen
mesh_terms: D001783:Blood Flow Velocity; D002302:Cardiac Output / Q000502:physiology; D002303:Cardiac Output, Low / Q000097:blood* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007231:Infant, Newborn / Q000378:metabolism* / Q000502:physiology; D007234:Infant, Premature; D008297:Male; D010100:Oxygen / Q000097:blood*; D010108:Oxyhemoglobins / Q000378:metabolism*; D010865:Pilot Projects; D014682:Vena Cava, Inferior; D014683:Vena Cava, Superior
chemical_list: D010108:Oxyhemoglobins; D010100:Oxygen