Cerebral oxygenation and blood flow in normal term infants at rest measured by a hybrid near-infrared device (BabyLux)

BACKGROUND: The BabyLux device is a prototype optical neuro-monitor of cerebral oxygenation and blood flow for neonatology integrating time-resolved reflectance spectroscopy and diffuse correlation spectroscopy. METHODS: Here we report the variability of six consecutive 30 s measurements performed in 27 healthy term infants at rest. Poor data quality excluded four infants. RESULTS: Mean cerebral oxygenation was 59.6 +/- 8.0%, with intra-subject standard deviation of 3.4%, that is, coefficient of variation (CV) of 5.7%. The inter-subject CV was 13.5%. Mean blood flow index was 2.7 x 10(-8) +/- 1.56 x 10(-8) (cm(2)/s), with intra-subject CV of 27% and inter-subject CV of 56%. The variability in blood flow index was not reduced by the use of individual measures of tissue scattering, nor accompanied by a parallel variability in cerebral oxygenation. CONCLUSION: The intra-subject variability for cerebral oxygenation variability was improved compared to spatially resolved spectroscopy devices, while for the blood flow index it was comparable to that of other modalities for estimating cerebral blood flow in newborn infants. Most importantly, the simultaneous measurement of oxygenation and flow allows for interpretation of the high inter-subject variability of cerebral blood flow as being due to error of measurement rather than to physiological instability.