Carotid Artery Doppler Flow Pattern after Deep Hypothermic Circulatory Arrest in Neonatal Piglets

The mechanisms of cerebral injury after cardiac surgery in neonates are not clear. The aim of the study was the analysis of flow changes in the carotid artery of neonatal piglets after deep hypothermic circulatory arrest (DHCA). Eight neonatal piglets were connected to cardiopulmonary bypass (CPB) and underwent (i) cooling to 18°C core temperature within 30 min, (ii) DHCA for 90 min, and finally (iii) rewarming to 37°C after cross-clamp release (60 min of reperfusion). The blood flow was measured in the left carotid artery by an ultrasonic flow probe before CPB (baseline; T0 ), immediately after termination of reperfusion on CPB (T1 ), 30 min later (T2 ), and 60 min later (T3 ). Additionally, the pulsatility index and the resistance index were calculated and compared. Finally, the relationship between the carotid artery flow and the corresponding pressure at each time-point was compared. After termination of CPB (T1 ), the mean carotid artery flow was reduced from 45.26 ± 2.58 mL/min at baseline to 23.29 ± 2.58 mL/min (P < 0.001) and remained reduced 30 and 60 min later (P < 0.001 vs. baseline). Both the pulsatility index and the resistance index were increased after termination of reperfusion, with the maximum occurring 30 min after CPB end. In conclusion, the carotid artery Doppler flow in neonatal piglets was reduced after DHCA, while the indices of pulsatility and resistance increased.