Detection of nontraumatic comatose patients with no benefit of intensive care treatment by recording of sensory evoked potentials

Objectives: To determine the predictive ability of sensory evoked potential recordings in nontraumatic comatose patients. To evaluate the hypothesis that patients with bilateral absent cortical responses ultimately die despite long-term intensive care treatment. Design: Prospective cohort study. Setting: Medical intensive care unit (ICU) of a university hospital. Patients: Four hundred forty-one adult nontraumatic comatose patients (unarousable unresponsiveness to external stimulation, Glasgow Coma Score less than or equal to 7) from various causes. Six hundred seventy-six sensory evoked potential measurements were performed within 7 days after onset of coma. Main Outcome Measures: Death or survival to hospital discharge. Results: Eighty-six patients (20%) had a bilateral loss of the cortical evoked potential N20 peak. Despite longterm intensive care treatment, all died without awakening from coma (mortality rate, 100%; 95% confidence interval, 96-100). The mean stay at the ICU after evoked potential measurement until death was 8.1 days (697 patient-days). The overall cost of ICU management for these 86 patients accounted for approximately $1324300. In the remaining 355 comatose patients with preserved cortical N20 peak, 148 (42%) survived and 207 (58%) died. In this latter group of patients, cervicomedullary N13 to cortical N20 conduction time was prolonged in nonsurvivors (mean+/-SD, 6.7+/-1.3 milliseconds) compared with that in survivors (mean+/-SD, 6.4+/-1.2 milliseconds, P<.05) and healthy controls (mean+/-SD, 5.5+/-0.4 milliseconds, P<.05). Although this difference is statistically significant, a preserved N20 peak is not useful to discriminate whether the individual patient will. survive (N13-N20 conduction time of >7 milliseconds had a positive predictive value of correct prediction of death of 0.67). Conclusions: Recording of sensor): evoked potentials identifies a subgroup of adult nontraumatic comatose patients with a mortality rate of 100% in our sample. In these patients, advanced intensive care treatment should be withdrawn to provide limited ICU resources for patients with higher probability of favorable outcome; We emphasize that these results are not applicable to comatose patients following closed head trauma and particularly not to children.