ESTIMATED CEREBRAL METABOLIC-RATE OF OXYGEN IN SEVERELY BRAIN-INJURED PATIENTS - A VALUABLE TOOL FOR CLINICAL MONITORING

Objective: 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. Design: Prospective, observational study. Setting: Neuroscience intensive care unit of a university hospital. Patients: Sixty-six adults with acute brain trauma undergoing Xe-133 regional cerebral blood now and global cerebral oxygen metabolic studies, in conjunction with other routine monitoring techniques. Interventions: None. Measurements and Main Results: Estimated cerebral metabolic rate of oxygen was calculated as the product of Paco(2) and arterio-jugular oxygen content difference, and compared with the measured cerebral metabolic rate of oxygen (the product of mean regional cerebral blood now and arterio-jugular oxygen content difference). Good correlations were found betw een the estimated and the true values (r(2) = .56/.67, p < .0001) in 91 studies performed in 66 patients. Conclusions: 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.