Cerebral Blood Flow Velocity and Oxygenation in Neonatal Aortic Arch Repair at Two Perfusion Temperatures.

OBJECTIVES: (i) To monitor cerebral blood flow velocity (CBFv) throughout aortic arch repair surgery and during recovery period in paediatric intensive care. (ii) To examine the relationship between near infrared spectroscopy (NIRS) and transcranial doppler ultrasound (TCD) during cardiac surgery. (iii) Examine CBFv in patients cooled to 20 °C and 25 °C.

METHODS: During aortic arch repair and after surgery, TCD was monitored in 24 neonates, alongside NIRS, blood pH, pO2, pCO2, HCO3, lactate, Hb, Htc (%) and temperature (core and rectal). General linear models were used to examine differences over time and cooling temperature. Repeated measured correlation (rmcor) were used to determine relationship between NIRS and TCD.

RESULTS: CBFv changed during arch repair procedure (main effect of time: p = 0.001). During cooling phase, CBFv increased by 10.0 cm/s (5.97 cm/s, 17.7 cm/s) compared to normothermic (p = 0.019). Once recovering in PICU, CBFv had increased from the preoperative measurement by 6.2 cm/s (0.21, 13.4; p = 0.045). CBFv changes were similar between patients cooled to 20 °C and 25 °C (main effect of temperature: p = 0.22). Repeated measures correlation identified a statistically significant but weak positive correlation between CBFv and NIRS (r = 0.25, p = <0.001).

CONCLUSIONS: Our data suggested that CBFv changed throughout aortic arch repair and was higher during cooling period. A weak relationship was found between NIRS and TCD. Overall, these findings could provide clinicians with information on how to optimise long-term cerebrovascular health.