Cerebral hemoglobin concentration and oxygen saturation measured by intensity modulated optical spectroscopy in the human fetus during labor.
OBJECTIVE
To quantify hemoglobin concentration and oxygen saturation in the human fetal brain using intensity modulated optical spectroscopy during labor.


METHODS
A specially designed probe was applied to the fetal scalp in 20 women during uncomplicated labor at term. Optical fibres transmitted near infra-red light to and from an intensity modulated optical spectrometer (IMOS), which detected changes in the optical parameters of the infra-red light source. Using novel off-line analytic techniques, these changes were converted into absolute measurements of oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb). Summing Hb and HbO2 gives total hemoglobin concentration (HbT) and HbO2/HbT x 100% provided measurements of cerebral saturation (SmcO2).


RESULTS
Of 20 fetuses studied, data from 10 fetuses were suitable for analysis. Over three consecutive uterine contractions, the mean (+/- SD) absolute cerebral concentrations of Hb and HbO2 were 30 +/- 18 and 46 +/- 21 mumol/l, respectively. This gave a mean cerebral HbT of 77 +/- 29 mumol/l and a mean SmcO2 of 59 +/- 12%. In the other ten fetuses insufficient light was detected to allow chromophore quantification.


CONCLUSIONS
These are the first absolute measurements of cerebral Hb and HbO2 in human fetuses during labor. The values of total hemoglobin are similar to those obtained in neonates with hypoxia-ischemia and the measurements of fetal cerebral oxygen saturation are similar to previously published values.
Chipchase
Jeremy
J
Department of Obstetrics and Gynecology, University College London, London, U.K.
Kirkby
David
D
Peebles
Donald
D
Cope
Mark
M
Rodeck
Charles
C
D005260:Female; D005333:Fetus / Q000378:metabolism*; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D007743:Labor, Obstetric / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D010108:Oxyhemoglobins / Q000378:metabolism; D011247:Pregnancy; D019265:Spectroscopy, Near-Infrared; D013687:Telencephalon / Q000098:blood supply / Q000196:embryology* / Q000378:metabolism; D014590:Uterine Contraction / Q000502:physiology
D006454:Hemoglobins; D010108:Oxyhemoglobins; D010100:Oxygen