title: Comparison of three methods to measure absolute cerebral hemoglobin concentration in neonates by near-infrared spectrophotometry.
abstract: Three methods by which to determine absolute total cerebral hemoglobin concentration (tHb in micromol/L) by near-infrared spectrophotometry (NIRS) have evolved: (1) tHbo, requiring oxygenation changes and arterial oxygen saturation measurements as a reference using a relative NIRS algorithm, (2) tHbg, using a geometrical multidistance principle and (3) tHbgo, a combination of both. The aim of this study was to compare the three methods quantitatively. Sixteen clinically stable preterm infants with a mean gestational age of 29.6 (range of 25.1-36.4) weeks, birthweight of 1386 (680-2820) g and a postnatal age of 2.5 (0.5-6) days, who needed supplemental oxygen, were enrolled. The mean+/-standard deviation tHbg was 150.2+/-41.8 micromol/L (range of 61.6-228.9 micromol/L), the tHbo was 62.1+/-27.2 micromol/L (26.0-110.8 micromol/L) and the tHbgo was 89.3+/-45.6 micromol/L (26.5-195.9 micromol/L). The correlation coefficient among the three methods were tHbg and tHbgo r=0.736; tHbo and tHbgo r=0.938; tHbg and tHbo r=0.598. A multiple regression with variable selection by Mellow's C(p) showed, that tHbg was correlated to the birthweight, the postnatal age, the heart rate and the pCO2 (r(2)=0.588), tHbo and tHbgo were associated with the hemoglobin concentration in the blood, the mean arterial blood pressure and the pCO2 (r(2)=0.493 and 0.406, respectively). The three methods (tHbg, tHbo, and tHbgo) give systematically different tHb readings and large intersubject variability.
authors.affiliation: University Hospital, Clinic for Neonatology, 8091 Zurich, Switzerland. martin.wolf@alumni.etchz.ch
authors.forename: Martin
authors.initials: M
authors.lastname: Wolf
authors.forename: Kurt
authors.initials: K
authors.lastname: von Siebenthal
authors.forename: Matthias
authors.initials: M
authors.lastname: Keel
authors.forename: Vera
authors.initials: V
authors.lastname: Dietz
authors.forename: Oskar
authors.initials: O
authors.lastname: Baenziger
authors.forename: Hans Ultrich
authors.initials: HU
authors.lastname: Bucher
mesh_terms: D001923:Brain Chemistry; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood / Q000378:metabolism*; D010100:Oxygen / Q000097:blood; D010108:Oxyhemoglobins / Q000032:analysis; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin; D010100:Oxygen