浙医一院 Neurosurgery
Neurosurgery
浙医一院 INTRACRANIAL DYNAMICS
INTRACRANIAL DYNAMICS
浙医 Fhe first principle is obvious: the cranial cavity has a fixed volume that is filled by various Ings 1. Brain tissue 2. CSF 3. Blood vessels and intravascular blood volume 4. Volume associated with any pathologic process which can include tumor, cyst, abscess hemorrhage, edema, necrosis
The first principle is obvious: the cranial cavity has a fixed volume that is filled by various things: 1. Brain tissue 2. CSF 3. Blood vessels and intravascular blood volume 4. Volume associated with any pathologic process, which can include tumor, cyst, abscess, hemorrhage, edema, necrosis
dhE- A consequence of this principle: If there is an elevation in the volume of any one compartment there is a stage of compensation in which the volume of one or more other compartments can be reduced to avoid elevations in Icp
A consequence of this principle: If there is an elevation in the volume of any one compartment, there is a stage of compensation in which the volume of one or more other compartments can be reduced to avoid elevations in ICP
QUESTION: What is Intracranial Pressure(ICP)? >CP: the pressure produced by the content of the cranial cavity(brain tissue, CSF and blood) on the cranial cavity wall >Normal cp: Adu|t:0.7~2.0kPa(70~200mH20)。 chi|d:0.5~1.0kPa(50~100mH20)
QUESTION: What is Intracranial Pressure (ICP)? ➢ICP：the pressure produced by the content of the cranial cavity (brain tissue, CSF and blood) on the cranial cavity wall. ➢Normal ICP： Adult：0.7～2.0 kPa（70～200mmH2O）。 Child：0.5～1.0kPa（50～100mmH2O）
The second principle is not 浙医一院 obvious and may seem counterintuitive The spinal fluid is produced at a constant rate(15-20 mL/hr) largely by the choroid plexus of the ventricles by an energy- dependent, physicochemical pI rocess
The second principle is not obvious and may seem counterintuitive: The spinal fluid is produced at a constant rate (∼15-20 mL/hr) largely by the choroid plexus of the ventricles by an energydependent, physicochemical process
浙一 The third basic principle. The cerebral blood flow(CBF) normally varies over a wide range (30-100 mL per 100g brain tissue per minute), depending on metabolic demand from neuronal activity within a particular area of the brain
The third basic principle: The cerebral blood flow (CBF) normally varies over a wide range (30-100 mL per 100 g brain tissue per minute), depending on metabolic demand from neuronal activity within a particular area of the brain
浙医一院 For any brain region CBF=Cerebral perfusion pressure/ Cerebral vascular resistance
For any brain region CBF=Cerebral perfusion pressure/ Cerebral vascular resistance
浙医一院 The fourth principle Injured tissue swells, making obvious the potential for a cascading injury by a vicious cycle. If the stage of compensation mentioned earlier, even with therapy, is exceeded and ICP is elevated high enough by whatever mechanism so that cerebral perfusion pressure(CPP) declines. cbf can decline to levels where tissue InJury occurs
The fourth principle: Injured tissue swells, making obvious the potential for a cascading injury by a vicious cycle. If the stage of compensation mentioned earlier, even with therapy, is exceeded and ICP is elevated high enough by whatever mechanism so that cerebral perfusion pressure (CPP) declines, CBF can decline to levels where tissue injury occurs
The vicious cycle. CPP. cerebral perfusion 浙医一院 pressure; ICP, intracranial pressure ICP CPP Infarction Edema
Edema Infarction ICP CPP The vicious cycle. CPP, cerebral perfusion pressure; ICP, intracranial pressure
