title: Transcutaneously measured near-infrared spectroscopic liver tissue oxygenation does not correlate with hepatic venous oxygenation in children.
abstract: OBJECTIVE
  To compare transcutaneous near-infrared spectroscopic (NIRS) measured liver tissue oxygenation with hepatic vein oxygen saturation (SvhO2) in children undergoing cardiac catheterization.
  
  
  METHODS
  A NIRS optode (containing an emitter and a receiver of near-infrared light) was placed directly below the right costal arch above the palpable liver in 40 children aged 0.02 to 7.28 yr (median: 1.8 yr). Spatially resolved spectroscopic measured tissue oxygenation index (TOI) was recorded using the NIRO-300. Paired blood samples from the hepatic vein were taken under radiological control for determination of SvhO2 in a co-oxymeter. TOI values were compared with hepatic vein oxygenation, with simultaneously obtained arterial oxygen saturation (SaO2), inferior vena cava SO2 and hemoglobin concentration using simple linear and multi-regression analysis.
  
  
  RESULTS
  TOI values ranged from 35% to 73% (58.6 +/- 8.4%); SvhO2 from 32% to 80% (58.4 +/- 14.4%), and arterial SO2 from 54% to 100% (90.0 +/- 11.4%). TOI and hepatic vein oxygen saturation failed to correlate (r = 0.052/P = 0.752). A regression model containing arterial saturation (Delta R2 = 0.177) and the ratio of pulmonary to systemic resistance (Delta R2 = 0.095) explained 27.3% of the observed variance in TOI. In this model, hepatic vein oxygen saturation was no longer significant; explaining only 3.4% of the variance. No other variable retained a significant association.
  
  
  CONCLUSIONS
  Transcutaneously measured NIRS tissue oxygenation with an optode placed over the palpable liver does not correlate with SvhO2. The value is dominated by non-hepatic variables such as arterial saturation and vascular resistances.
authors.affiliation: Department of Intensive Care and Neonatology, University Children's Hospital, Zurich, Switzerland. markus.weiss@kispi.unizh.ch
authors.forename: Markus
authors.initials: M
authors.lastname: Weiss
authors.forename: Gabriele
authors.initials: G
authors.lastname: Schulz
authors.forename: Margrit
authors.initials: M
authors.lastname: Fasnacht
authors.forename: Christian
authors.initials: C
authors.lastname: Balmer
authors.forename: Joachim E
authors.initials: JE
authors.lastname: Fischer
authors.forename: Andreas C
authors.initials: AC
authors.lastname: Gerber
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Bucher
authors.forename: Oskar
authors.initials: O
authors.lastname: Baenziger
mesh_terms: D002648:Child; D002675:Child, Preschool; D005260:Female; D006503:Hepatic Veins / Q000378:metabolism*; D006801:Humans; D007223:Infant; D008099:Liver / Q000378:metabolism*; D008297:Male; D010100:Oxygen / Q000378:metabolism*; D012867:Skin; D019265:Spectroscopy, Near-Infrared
chemical_list: D010100:Oxygen