Cerebral hemodynamics on near-infrared spectroscopy in hypoxia and ischemia in young animal studies.

Using near-infrared spectroscopy the changes of intracranial oxyhemoglobin, deoxyhemoglobin, total hemoglobin and cytochrome aa3, which show the progression of intracranial oxygenation, hemodynamics and cell metabolism, were recorded during prolonged partial hypoxia induced by carbon dioxide (CO2) and nitrogen (N2), ischemia induced by hyperventilation, and hypoxia during hypoglycemia in neonatal and young rabbits. The reduction of cytochrome aa3 during the terminal stage of CO2-induced prolonged hypoxia, hyperventilation and hypoxia in hypoglycemia suggests that the redox state of cytochrome aa3 will be changed by several combined factors such as oxygen delivery, ATP demand and substrate (glucose) delivery.