LAUSR

Abstract. Significance Hyperspectral near-infrared spectroscopy (hsNIRS) combined with diffuse correlation spectroscopy (DCS) provides a noninvasive approach for monitoring cerebral blood flow (CBF), the cerebral metabolic rate of oxygen (CMRO2) and the oxidation state of cytochrome-c-oxidase (oxCCO). CMRO2 is calculated by combining tissue oxygen saturation (StO2) with CBF, whereas oxCCO can be measured directly by hsNIRS. Although both reflect oxygen metabolism, a direct comparison has yet to be studied. Aim We aim to investigate the relationship between CMRO2 and oxCCO during periods of restricted oxygen delivery and lower metabolic demand. Approach A hybrid hsNIRS/DCS system was used to measure hemodynamic and metabolic responses in piglets exposed to cerebral ischemia and anesthetic-induced reductions in brain activity. Results Although a linear relationship was observed between CMRO2 and oxCCO during ischemia, both exhibited a nonlinear relationship with respect to CBF. In contrast, linear correlation was sufficient to characterize the relationships between CMRO2 and CBF and between the two metabolic markers during reduced metabolic demand. Conclusions The observed relationship between CMRO2 and oxCCO during periods of restricted oxygen delivery and lower metabolic demand indicates that the two metabolic markers are strongly correlated.