Estimated cerebral metabolic rate of oxygen in severely brain-injured patients: a valuable tool for clinical monitoring.

Abstract

To evaluate a novel parameter of global cerebral oxygen metabolism, the estimated cerebral metabolic rate of oxygen, for its clinical utility in monitoring acute, severely brain-injured patients. Prospective, observational study. Neuroscience intensive care unit of a university hospital. Sixty-six adults with acute brain trauma undergoing 133Xe regional cerebral blood flow and global cerebral oxygen metabolic studies, in conjunction with other routine monitoring techniques. None. Estimated cerebral metabolic rate of oxygen was calculated as the product of PaCO2 and arterio-jugular oxygen content difference, and compared with the measured cerebral metabolic rate of oxygen (the product of mean regional cerebral blood flow and arterio-jugular oxygen content difference). Good correlations were found between the estimated and the true values (r2 = .56/.67, p < .0001) in 91 studies performed in 66 patients. These findings suggest that the estimated cerebral metabolic rate of oxygen is a useful substitute for the traditional cerebral metabolic rate of oxygen when cerebral blood flow information is not available. In addition, with this parameter, the patient's metabolic status can be assessed more frequently than with cerebral blood flow studies. These measurements do not require special instrumentation and can be done in any intensive care setting.