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 the recovery period. (ii) To examine the relationship between transcranial doppler ultrasound (TCD) and near-infrared spectroscopy (NIRS) during cardiac surgery. (iii) To examine CBFv in patients cooled to 20°C and 25°C.

METHODS

During aortic arch repair and after surgery, measurements of TCD, NIRS, blood pH, pO2, pCO2, HCO3, lactate, Hb, haematocrit (%) and temperature (core and rectal) were recorded in 24 neonates. General linear mixed models were used to examine differences over time and between two cooling temperatures. Repeated measures correlations were used to determine the relationship between TCD and NIRS.

RESULTS

CBFv changed during arch repair (main effect of time: P = 0.001). During cooling, CBFv increased by 10.0 cm/s (5.97, 17.7) compared to normothermia (P = 0.019). Once recovering in paediatric intensive care unit (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 correlations (rmcorr) 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 the 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.