Electroencephalogram indices in patients undergoing cardiac arrest

Objective: to assess the safety of indicators of electrical activity of the brain for the approach to the analysis of the basic neurophysiological mechanisms of the brain in patients after cardiac arrest. Materials and methods: 52 patients were examined (age — 54,68 ± 19,33) after cardiac arrest. At the time of recording the electroencephalogram (EEG), the level of wakefulness of the examined patients on the Glasgow coma scale was in the range of 3 to 13 points. In 35 patients, EEG recording was performed starting from the first three days from the moment of cardiac arrest, in 17 patients — from the fourth to the 18th day. EEG was registered on electroencephalographs ‘Encephalan–EEGR–19/26’ by ‘Medikom MTD’, ‘Neuron-Spectrum–5/EP’ and ‘Neuron-Spectrum–65’ by ‘Neurosoft’ in accordance with the recommendations of the International Federation of Clinical Neurophysiologists (IFCN). The duration of a single EEG recordings lasted at least 30 min. To localize equivalent dipole sources of pathological activity we used the program ‘BrainLoc 6.0’, (Russia). In 19 patients EEG was recorded in dynamics from 2 to 8 times. Results: all patients showed EEG changes of varying severity, which can be divided into three groups (according to the severity of changes in the EEG: moderate, severe and rough). In the group of patients with gross changes in EEG can be identified 4 variants: the first variant — absence of the alpha rhythm and the dominance of slow-wave fluctuations of the frequency spectrum; variant II — continuous generalized paroxysmal activity; variant III — phenomenon of ‘burst-suppression’; variant IV — a marked decrease in the amplitude of electrical activity of the brain to the level of 2–4 microvolt. Conclusions: based on the dynamics of the EEG pattern in patients after cardiac arrest, it is possible to assume with a certain degree of probability the level of violations in the basic mechanisms of the brain.