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 < or = 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 long-term 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 $1,324,300. 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 sensory 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 In these patients, advanced intensive care treatment should be withdrawn to provide limited ICU resources for patients with higher probability of favorable outcome.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.