[Various mechanisms regulating intracranial pressure in organic lesions of the brain].

Changes in epidural intracranial pressure in 52 patients with organic lesions of the brain (tumors, severe craniocerebral injury) was studied for 1-10 days of the acute postoperative period. The tone of the cerebral vessels was studied from the values of pulse and respiratory fluctuations of intracranial pressure during spontaneous and induced hyperventilation, in inhalation of moistened oxygen, when the patient awakens and falls asleep. Duction of intracranial pressure at the peak of the hypocapnic effect and during oxygen inhalation as well as reduction of intracranial pressure at the moment of awakening ("the awakening effect") were recorded. Increased tone of the cerebral vessels was revealed during awakening, evidence of which was a decrease in the amplitude of pulse fluctuations of epidural intracranial pressure. The period of falling asleep was marked by a decrease in the tone of the cerebral vessels which was manifested on the intracranial pressure tracings by increased pulse fluctuations and led to increase of intracranial pressure. It was established that changes in the tone of the cerebral vessels and in their activity determining the different blood content of the brain are among the mechanisms of intracranial pressure regulation.