Background: Neonates with complex congenital heart defects have traditionally undergone surgery during deep hypothermic cardiac arrest (HCA). Selective cerebral perfusion (SCP) is thought to minimize ischemic brain injury by providing adequate cerebral blood flow. We investigated SCP with different flow rates compared with HCA with respect to cerebral perfusion and tissue oxygenation as assessed by near-infrared spectroscopy.
Methods: Twenty-one piglets were placed on cardiopulmonary bypass at 18 degrees C, then underwent either HCA or SCP at 25 or 50 mL x kg(-1) x min(-1) for 90 min. The blood flow index (BFI) derived by indocyanine green and tissue oxygen index (TOI) were determined by near-infrared spectroscopy. Mean cerebral blood flow velocity (FV(mean)) was recorded by transcranial Doppler ultrasound.
Results: Both BFI and FV(mean) increased significantly (126 +/- 27% of baseline; 19 +/- 2 cm/s) in the SCP 50 group compared with HCA (no flow) and SCP 25 (65 +/- 24%; 10 +/- 1 cm/s), respectively. TOI increased in the SCP 50 group compared with baseline (74 +/- 4% vs 65 +/- 4%), and was higher compared with HCA (52 +/- 2%) and SCP 25 (59 +/- 2%). Intracranial pressure increased nonsignificantly compared with baseline in the SCP 50 group.
Conclusions: Both BFI and FV(mean) suggested increased cerebral perfusion in the SCP 50 group compared with the HCA and SCP 25 groups. TOI was significantly higher in both the SCP 25 and SCP 50 groups compared with HCA. SCP at 25 mL x kg(-1) x min(-1) may be most appropriate for cerebral protection.