Acute cerebral edema
Acute cerebral edema
brain trauma, surgical intervention (brain surgery), toxic and infectious processes, hydration, some acute poisoning, disorders of cerebral blood flow, acute asphyxia.
An adult healthy person has a cerebralblood flow accounts for up to 15% of the minute heart volume, oxygen consumption reaches 20% of total intake (on average from 40 to 50 ml / min), it decreases with hypothermia. If the systemic arterial pressure decreases, the brain vessels expand and the cerebral blood flow does not change. However, the decrease in blood pressure is below 60 mm Hg. can not be compensated for by the corresponding expansion of the cerebral vessels, therefore, cerebral ischemia occurs. Increasing blood pressure above the norm does not create the prerequisites for hypervolemia of the brain, as the vessels of the brain narrow and, thanks to increased resistance, cerebral blood flow remains normal. The tonus of the vessels of the brain decreases when hypoxia develops, sharp metabolic acidosis, hypercapnia, blood viscosity and intracranial pressure increase. Increased vascular tone is observed with hypocapnia, hyperoxia, metabolic alkalosis.
Due to injury, intoxication, poisoning orViolations of cerebral blood flow occur severe vasodilation or even vasoplegia and capillaries are overwhelmed with blood. The hydrostatic pressure rises and the processes of fluid transudation begin to prevail over reabsorption. Excessive amounts of blood are partially shunted through arterio-venous anastomoses. Increases in circulatory hypoxia and metabolic acidosis. Violated energy metabolism in the brain cells. As a result, the blood flow slows down, stasis is formed, sequestration and even microembolism of cerebral vessels are possible. Violations of the brain's functions entail disturbances in breathing, circulation, and pathological changes in other body systems.
The edema of the brain is characterized by a headache,nausea, vomiting, mental and motor anxiety, followed by further oppression and complete adynamy. When the shells of the brain are irritated, stiff neck muscles are noted, the symptoms of Kernig, Brudzinsky, etc. are reduced tendon reflexes, becomes asymmetric Babinsky's symptom, the attempt to cause the knee-jerk reflex ends with the bending of the legs in the knees. The most informative symptoms are the increased intracranial pressure: disorientation in the initial stages and loss of consciousness in later stages of cerebral edema. Stagnant phenomena are observed on the fundus. As a result of further strengthening of the compression of the brain, the processes of exudation and hemorrhage into the retina are revealed, and the pressure of the cerebrospinal fluid increases.
Acute cerebral edema is one of the most formidable conditions, for the elimination of which urgent measures are needed in the intensive care unit.