UDC

612.1:612.821

Authors

Denis B. Demin*, Liliya V. Poskotinova*
*Federal Center for Integrated Arctic Research, Russian Academy of Sciences (Arkhangelsk, Russian Federation)
Corresponding author: Denis Demin, address: prosp. Lomonosova 249, Arkhangelsk, 163000, Russian Federation;
e-mail: denisdemin@mail.ru

Abstract

The paper studied the changes in electroencephalographic parameters during prolonged voluntary hyperventilation in 30 healthy men aged 18–20 years. Continuous monitoring of blood gases (carbon dioxide and oxygen) and oxygen saturation was performed using the Radiometer Medical TCM40 transcutaneous monitoring system. Electroencephalograms (EEG) were recorded unipolarly in 16 standard leads during each stage of the study using EEGA-21/26 Encephalan-131-03 EEG analyser; the subjects were in a state of quiet wakefulness with their eyes closed. Having recorded the initial values of the parameters under study, we performed cyclic hyperventilation, during which the external respiration rate increased on the average by a factor of 4 to 5: at the first stage, until the transcutaneous carbon dioxide tension reached 25 mm Hg, and then, after rest and recovery, at the second stage of hyperventilation, until it reached 15 mm Hg. We show that the detected EEG changes during prolonged hyperventilation directly depend on the level of transcutaneous carbon dioxide tension. Hypocapnia with carbon dioxide level of 15 mm Hg caused a more pronounced increase in both intracortical and deep limbic-reticular activity of the brain, manifested in an increase in all types of EEG activity; moreover, in more than 70 % of cases we saw generalized paroxysmal activity. The initial EEG pattern after the end of hyperventilation was restored long before the recovery of carbon dioxide tension specific to each subject. The parameters of oxygen saturation continued to decrease even after the test, which can be a factor of delayed hypoxia in response to prolonged hyperventilation.

Keywords

hyperventilation, cyclic respiration, electroencephalogram, hypocapnia, hypoxia

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