Near Infrared Spectroscopy (NIRS) is an emerging technique for
brain oxygenation monitoring in newborns complicated by acute and chronic hypoxia. However, data regarding cerebral
oxygenation normal values are still lacking and matter of debate. Therefore, we investigate whether NIRS parameters in healthy
preterm/term infants are
gestational age and delivery modalities dependent and
correlate with standard monitoring parameters. From January to December 2007, 100 healthy newborns with
gestational age from 30 to 42 weeks' gestation were evaluated. Routine laboratory variables, daily clinical and
neurological evaluation and
ultrasound imaging were performed. The regional cerebral
oxygen saturation (rSO2) and fractional cerebral tissue oxygen extraction (FTOE) were measured by NIRS in the first 6-hours after birth. Data were recorded by MetaVision ICU X-Edition software and analyzed by
SPSS statistical package. rSO2 and FTOE
correlated (R=-0.77; R=0.41; P<0.01, for both) with
gestational age. Highest rSO2 and the lowest FTOE peaks (P<0.001, for all) were found at 30-33 wks when compared with other monitoring periods. From 34 wks onwards, rSO2 progressively decreased and FTOE increased reaching their lower dip/peak (P<0.001, for all) at 38-39 weeks. rSO2 and FTOE values were significantly different (P<0.05, for both) between
preterm and term newborns when corrected for delivery modality. rSO2
correlated (P<0.001 for all) with
heart (r=0.63),
respiratory (r=-0.58) rate, and with
arterial oxygen saturation (r=0.65). In conclusion, in the first 6-hours after birth cerebral
oxygenation in healthy newborns is
gestational age-dependent and
correlated with routine parameters. NIRS reference curve could be particularly useful in sick newborns
brain monitoring.
