DEATH OF THE BRAIN (synonym brain death) — the morbid condition connected with a total necrosis of a brain, and also the first cervical segments of a spinal cord at the kept cordial activity and the gas exchange provided by means of continuous artificial ventilation of the lungs. Page of m it is caused by the termination of blood circulation in a brain coming at sharp increase in intracranial pressure and its equalizing with the system ABP.
Pages of m for the first time described in 1959 Mr. Mollare and Gulon (R. Mollaret, M. of Goulon). They tracked the termination of all functions brain (see) in the conditions of long artificial ventilation of the lungs (see. Artificial respiration ) also called such state an ultraboundary coma. Further such terms as «the dissociated death», «a condition of a deanimation», «heart-lung preparation», «artificially continued agony», etc. were offered. Pathologists use also the term «respiratory brain».
Reliable morfol. S.'s sign of m is the necrosis of cerebral hemispheres, a cerebellum, a brain trunk, C1-2 of segments of a spinal cord which is not followed by glial reaction and coming to the end with a lysis of tissue of brain. In the conditions of the remaining cordial activity and the continuous artificial ventilation of the lungs (AVL) wet brain accrues in the beginning (see Hypostasis and swelling of a brain). At the same time its weight increases, fabric becomes flabby, there are subarachnoidal hemorrhages (see. the Subshell hemorrhages ). The departments of a brain restrained owing to hypostasis, napr, almonds of a cerebellum, hooks of a parahippocampus of lny crinkles, are exposed to disintegration and to an autolysis (see). The necrosis of neurons, treatment by plasma of tissue of brain, disintegration of walls of vessels is everywhere noted. In a subarachnoid space of a spinal cord the come-off particles of nekrotizirovanny bark of a cerebellum are found, to-rye with current of cerebrospinal liquid are displaced sometimes to a horse tail. The necrosis of C1-2 of segments results from the termination of a blood-groove in vertebral arteries, branches to-rykh provide blood supply of these segments. Sometimes in the specified segments of a spinal cord the picture of a hemorrhagic heart attack is observed (see).
Wedge, picture it is characterized by steady and full switching off of all functions of c. N of page. At the same time there is no consciousness and own breath, all motor reactions on external irritations, tendon, periosteal, cutaneous reflexes disappear, the atony of muscles is noted, there is no reaction of pupils to strong direct light (pupils keep the identical diameter exceeding 5 mm), corneal, okolovestibulyarny reflexes are not defined — caloric is not observed nystagmus (see), the movements in response to irritation of muscles of eyes, persons, the language innervated craniocereberal do not come to light (cranial, T.) nerves. Strong advance of an endotracheal tube in a trachea, advance of a catheter in bronchial tubes at suction of slime do not cause a gag reflex, reflexes from a mucous membrane of a nasopharynx and tussive movements. Strong pressure upon eyeballs is not followed bradikardny, the atropinic test is negative (after intravenous administration of 2 ml of 0,1% of solution of Atropini sulfas there does not occur increase of pulse). Also there is no spontaneous and caused electric activity of a brain. At the time of death of a brain and switching off of functions of a brain trunk along with the termination of own breath the collapse with falling of the ABP to zero develops. The stopped own breath in the conditions of S. is never recovered by m, but the ABP can be supported on datum level under the influence of pressor amines. In rare instances there is a spontaneous recovery of the ABP on low figures (80/50 mm of mercury.), what is explained by preservation of spinal regulation of a hemodynamics.
In 6 — 48 hours after S.'s approach the m is recovered reflex activity of a spinal cord, edges remains up to a cardiac standstill. At the same time there are monosinaptichesky myotatic contractions of sinews of tricipital, two-headed muscles, akhillova and knee jerks. At shaped irritation of skin of a front surface of a thorax and stomach global reductions of muscles of a trunk, and sometimes and extremities with inclusion of the muscles opposite on function are observed. Widespread reduction of muscles of a prelum abdominale at shaped irritation of skin of a stomach is characteristic. After recovery of autonomous functions of a spinal cord the ABP and body temperature raises a little that is caused by their partial regulation at the spinal level.
Diagnosis establish on the basis a wedge, data provided that there are no suspicions on a possibility of reception of the somnolent and other means oppressing activity of a brain the possibility of a hypothermia, metabolic and endocrine disturbances is excluded.
The defining S.'s sign of m is the lack of own breath caused by death of structures of a respiratory center. Apply test on a hypercapnia without anoxemia (apnoetichesky oxygenation, or the dividing test) to definition of lack of own breath, at the same time in the beginning carry out artificial ventilation of the lungs of 100% by oxygen within 1 hour, then switch-off the device IVL and 100% give oxygen through the catheter entered into an endotracheal or tracheostomy tube with a speed of 6 — 8 l of 1 min. At this time watch a rubber control bag of the device, changes of volume to-rogo allow to judge emergence of own breath. During the conducting this test carry out monitor overseeing of the ABP, an ECG, pulse rate, gas composition of blood. For the purpose of control of gas composition of blood gather an arterial blood through the constant catheter entered into a beam or femoral artery right after disconnection from IVL and then in 5, 10, 15 and 30 min. At deaths door brain indicators of the ABP, ECG, pulse rate, PaO 2 remain constants. Lack of respiratory movements at increase of PaCO 2 it is higher than 60 mm of mercury. (7,99 MPas), i.e. the threshold sizes necessary for excitement of a respiratory center, is the most reliable sign of death of its structures. In S.'s diagnosis the m
is important electroencephalography (see), with the help the cut comes to light so-called electric silence of a cerebral cortex. In these cases of EEG it is necessary to register continuously not less than 30 min. and not less than 10 min. at action of light, sound and painful irritants.
An important sign of S. of m is the termination of cerebral circulation revealed with the help angiography (see). At the same time the radiopaque substance entered into the general carotid arteries stops at the level of a siphon on a base of skull of a pla in a cervical part of an internal carotid artery; at an axial angiography — at the level of the main (basilar. T.) or vertebralny artery. During the carrying out this research in the conditions of S. the m is recommended to reduce intracranial pressure, system during an angiography shall be the ABP its less than 60 mm of mercury. In 30 min. after carrying out the first carry out a repeated angiography.
Within the first hour after S.'s registration m and constantly for the first 12 — 24 hours are noted metabolic disturbances and disorders of gas exchange in a brain. At the same time the critical size of speed drop of consumption by a brain of oxygen consider from 0,3 to 0,48 ml on 100 g of tissue of brain in 1 min. (it is normal of 3.3 mg / 100 of tissue of brain in 1 min.). Anaerobic oxidation in tissue of a brain is followed by accumulation milk to - you, the quantity a cut in cerebrospinal liquid increases up to 10 — 15 mmol/l (it is normal of 1,87 — 2.03 mmol/l). Results and diagnostic tests write down a wedge, inspections in special maps at least every 12th hour.
The concept «death of a brain» is not identical to the concept «biological death» though approach biol. death in these cases, at the current state of medicine, inevitably. Duration of a state, during to-rogo, despite S. of m, can remain or medicamentally be supported more or less adequate cordial activity at the proceeding IVL, fluctuates from several hours to 5 — 6 days; in some cases duration of this state increases to 4 weeks
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L. M. Popova.