Computing cerebral autoregulation markers from near-infrared spectroscopy and transcranial Doppler device during general anesthesia

The preservation of dynamic cerebral autoregulation (dCA) is crucial during cardiac surgery. dCA is usually computed from variations of mean cerebral blood velocity (MCBv), as derived from transcranial Doppler (TCD) device, and mean arterial pressure (MAP). Recently, regional oxygen saturation (rSO2), acquired via near-infrared spectroscopy (NIRS), was proposed to compute dCA. In this study, synchronous MAP, MCBv and rSO2 beat-to-beat series were recorded in 16 patients (age 59.4 ± 11.6 yrs, 13 males) scheduled for cardiac surgery before and after propofol general anesthesia induction. The percentage of segments exhibiting a Pearson correlation coefficient r of MCBV on MAP (rMCBv-MAP) and of rSO2 on MAP (% rsoz-map) significantly different from 0 was derived via a running approach. Findings show that % rso2-map was lower than rMCBv MaP regardless of experimental condition with a tendency towards a reduction during general anesthesia. Findings suggest that NIRS-based approach to dCA assessment provides different information compared to TCD-based one.