Cerebrovascular reactivity to carbon dioxide tension in newborns: data from combined time-resolved near-infrared spectroscopy and diffuse correlation spectroscopy

SIGNIFICANCE: Critically ill newborns are at risk of brain damage from cerebrovascular disturbances. A cerebral hemodynamic monitoring system would have the potential role to guide targeted intervention. AIM: To obtain, in a population of newborn infants, simultaneous near-infrared spectroscopy (NIRS)-based estimates of cerebral tissue oxygen saturation ([Formula: see text]) and blood flow during variations of carbon dioxide tension ([Formula: see text]) levels within physiologic values up to moderate permissive hypercapnia, and to examine if the derived estimate of metabolic rate of oxygen would stay constant, during the same variations. APPROACH: We enrolled clinically stable mechanically ventilated newborns at postnatal age [Formula: see text] without brain abnormalities at ultrasound. [Formula: see text] and blood flow index were measured using a non-invasive device (BabyLux), which combine time-resolved NIRS and diffuse-correlation spectroscopy. The effect of changes in transcutaneous [Formula: see text] on [Formula: see text] , cerebral blood flow (CBF), and cerebral metabolic rate of oxygen index ([Formula: see text]) were estimated. RESULTS: Ten babies were enrolled and three were excluded. Median GA at enrollment was 39 weeks and median weight 2720 g. [Formula: see text] increased 0.58% (95% CI 0.55; 0.61, [Formula: see text]), CBF 2% (1.9; 2.3, [Formula: see text]), and [Formula: see text] 0.3% (0.05; 0.46, [Formula: see text]) per mmHg increase in [Formula: see text]. CONCLUSIONS: BabyLux device detected [Formula: see text]-induced changes in cerebral [Formula: see text] and CBF, as expected. The small statistically significant positive relationship between [Formula: see text] and [Formula: see text] variation is not considered clinically relevant and we are inclined to consider it as an artifact.