Assessing the relationship between the cerebral metabolic rate of oxygen and the oxidation state of cytochrome-c-oxidase

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 ([Formula: see text]) and the oxidation state of cytochrome-c-oxidase (oxCCO). [Formula: see text] is calculated by combining tissue oxygen saturation ([Formula: see text]) 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 [Formula: see text] 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 [Formula: see text] and oxCCO during ischemia, both exhibited a nonlinear relationship with respect to CBF. In contrast, linear correlation was sufficient to characterize the relationships between [Formula: see text] and CBF and between the two metabolic markers during reduced metabolic demand. CONCLUSIONS: The observed relationship between [Formula: see text] and oxCCO during periods of restricted oxygen delivery and lower metabolic demand indicates that the two metabolic markers are strongly correlated.