683 - Cardiac output and regional-cerebral-oxygen-saturation in preterm neonates during immediate postnatal transition - an observational study

Cardiac output (CO) provides information about cerebral autoregulation when used with cerebral-regional-oxygen-saturation (crSO₂), which can be obtained with near-infrared spectroscopy (NIRS).
CrSO₂ depends on oxygen delivery and consumption. The oxygen delivery depends on hemoglobin, arterial oxygen saturation, and cerebral perfusion. The latter relies on cerebral vascular resistance and cerebral perfusion pressure (CPP), which depends on CO and systematic vascular resistance. Due to intact cerebral autoregulation, constant cerebral blood flow (CBF) is maintained, regardless of CO or systemic vascular resistance. However, impaired autoregulation leads to a positive correlation between CO and CBF, due to a passive pressure-dependent cerebral perfusion, which cause deleterious CBF, due to CPP variation

Objective:

To assess whether CO is associated with crSO₂ and cerebral-fractional-tissue-oxygen-extraction (cFTOE) during immediate transition in preterm neonates with respiratory support and term neonates without respiratory support

Design/Methods: Post-hoc analyses of secondary outcome parameters of prospective observational studies were performed. Neonates with cerebral NIRS monitoring values from minute 13 to 15 minute after birth and an oscillometric blood pressure measurement in the 15th minute after birth were eligible. Preterm neonates receiving respiratory support during immediate transition after birth and stable term neonates were included. Heart rate (HR) and arterial oxygen saturation (SpO₂) were monitored using pulse oximetry. CO values were calculated with Liljestrand & Zander formula out of mean HR from minute 13 to 15 minute after birth and blood pressure values in the 15th minute after birth. CO values were correlated with mean crSO₂ and cFTOE values from minute 13 to 15 minute after birth

Results:

In total, 199 preterm and term neonates were included.
In 59 preterm neonates with a gestational age of 29.3±3.7weeks with respiratory support, CO correlated significantly positively with crSO₂ (r=0.31 P=0.017) and significantly negatively with cFTOE (r=-0.30 P=0.022). In comparison, in the control group consisting of 140 stable term neonates with a gestational age of 38.7±0.7weeks, no significant correlation could be observed

Conclusion(s): In compromised preterm neonates, CO was associated with crSO₂ and cFTOE during immediate transition, whereas in stable term neonates, no associations were observed. These findings suggest that passive-pressure-dependent cerebral perfusion was present in compromised preterm neonates receiving respiratory support, indicating impaired cerebral autoregulation