A noninvasive method for monitoring the effects of increased intracranial pressure with near infrared spectrophotometry

Abstract

Two experiments were conducted to assess the feasibility of near infrared spectrophotometry (niroscopy) to monitor directly the effects of increased intracranial pressure on brain metabolism. ICP was increased in cats by subarachnoid infusion of a "mock" CSF solution. Cytochrome a,a3 redox state, oxyhemoglobin, deoxyhemoglobin and cerebral blood flow were noninvasively and continuously monitored by niroscopy. The results of both experiments indicated that changes in ICP correlated with a reduction in cytochrome a,a3 redox state (p less than 0.01), a decrease in the quantity of oxyhemoglobin and cerebral flow (p less than 0.01) and an increase in deoxyhemoglobin. The study results suggest that niroscopy has the potential for providing noninvasive and continuous data for assessing brain metabolic activity. The correlations obtained with simultaneous measurements of intracranial pressure make this an attractive method for application to those at risk for increased intracranial pressure.