Intracranial Pressure - University of Windsor颅内压-温莎大学.pptVIP

REPONSE OF BRAIN TISSUE TO TRAUMA INTRACRANIAL PRESSURE Intracranial Pressure Response of brain tissue to trauma occurs at the cellular level: Injury: massive vasodilation Cerebral edema: increase in size and volume of brain Increased ICP: Increase in pressure exerted within the cranial cavity Intracranial Pressure Skull has three essential components: - Brain tissue = 78% - Blood = 12% - Cerebrospinal fluid (CSF) = 10% Any increase in any of these tissues causes increased ICP Components of the Brain Intracranial Pressure Normal ICP = 4 -15 mmHg Factors that influence ICP Arterial pressure Venous pressure Intraabdominal and intrathoracic pressure Posture Temperature Blood gases (CO2 levels) Intracranial Pressure The degree to which these factors ? ICP depends on the ability of the brain to accommodate to the changes Intracranial PressureRegulation and Maintenance Normal intracranial pressure The pressure exerted by the total volume from the brain tissue, blood, and CSF If the volume in any one of the components increases within the cranial vault and the volume from another component is displaced, the total intracranial volume will not change Intracranial Volume-Pressure Curve Intracranial PressureRegulation and Maintenance Normal compensatory adaptations Alteration of CSF absorption or production Displacement of CSF into spinal subarachnoid space Dispensability of the dura Intracranial PressureCerebral Blood Flow Definition The amount of blood in milliliters passing through 100 g of brain tissue in 1 minute About 50 ml/min per 100 g of brain tissue Intracranial PressureImportance of ICP to BP and CPP Brain needs constant supply O2 and Glucose BP: heart delivers blood to brain at an average BP of 120/80 (Mean BP = 100); this mean arterial pressure (MAP) must be higher than ICP CPP (Cerebral Perfusion Pressure): is the pressure needed to overcome ICP in order to deliver O2 nutrients Intracranial PressureImportance of ICP to BP and CPP MAP is