The prognostic value of EEG in coma survivors after cardiac arrest.

Abstract

EEG was recorded in 64 patients while they were in a state of moderate coma after cardiac arrest. The clinical course of the patients was followed, and the prognosis was compared with the EEG findings.A total of 59 patients died within periods ranging from 1 to 287 days, 57 without having regained consciousness. Five patients survived, all with cerebral sequelae. The immediate causes of death were brain death in 18, pneumonia in 24, and cardiovascular complications in 17 cases. Autopsy was performed in 54 patients.The EEGs were visually graded and classified into five groups, in order of increasing abnormalities (Hockaday et al. 1965). Of the records, 17% were unclassifiable. An extremely abnormal EEG (grade V) was indicative of death after a few days, while other grades of EEG changes did not give any prognostic indications. Good correlation was disclosed by multiple regression analysis between the length of the survival time and the EEG changes estimated on the basis of 12 variables.A method is described by which it is possible to estimate the probable length of survival of a patient from his EEG records. There was a fair correlation between the estimated and observed survival times, except in the patients who died from cardiovascular complications after a few days. In these cases the prediction from the EEG was too optimistic.It is concluded that EEG is a useful supplement to the clinical evaluation of patients in coma after cardiac arrest. The EEG must be assessed in a special way, as simple visual grading is of only limited prognostic value.