The role of diffuse correlation spectroscopy and frequency-domain near-infrared spectroscopy in monitoring cerebral hemodynamics during hypothermic circulatory arrests

Real-time noninvasive cerebral blood flow monitoring during cardiac surgery could help optimize neuroprotective measures and hence decrease rates of neurologic injury associated with hypothermic circulatory arrests (HCAs). We used combined frequency-domain near-infrared spectroscopy and diffuse correlation spectroscopy (FDNIRS-DCS) to measure hemoglobin oxygen saturation (SO2), cerebral blood flow index (CBFi), and cerebral metabolic rate of oxygen (CMRO2i) in 12 adults undergoing HCA (4 HCA-only, 3 retrograde cerebral perfusion [RCP], 5 antegrade cerebral perfusion [ACP]). We coacquired regional oxygen saturation (rSO2) from a hospital oximeter (INVOS), mean arterial blood pressure (MAP), and nasopharyngeal temperature. Our measurements revealed that during HCA with RCP CBFi drops to almost zero and overshoots above baseline when circulation is restarted, similar to the CBFi behavior found during HCA-only. As a consequence of the low perfusion, with RCP and HCA-only SO2 decreases during HCA; in contrast, both CBFi and SO2 are mostly maintained with ACP.