Effects of mild hypothermic cardiopulmonary bypass on cerebral hemodynamics: comparison of diffuse optical and cerebral microdialysis metrics in neonatal swine

Mild hypothermic cardiopulmonary bypass (CPB) is used during neonatal cardiac surgery. To elucidate potential risk factors for brain injury, diffuse optical spectroscopy, diffuse correlation spectroscopy, and cerebral microdialysis techniques were employed to monitor cerebral hemodynamics during mild hypothermic CPB in a swine model. Optical metrics were further compared with microdialysis metrics. Stable microdialysis metabolite levels, a significant decrease in CMRO2, and trending (but not significant) decreases in CBF and increases in OEF were observed. This suggests that the optical metrics may be more sensitive to neurologic injury during CPB than microdialysis.