Altered Neurological Fx Flashcards
Name the three contents of cranial vault
brain tissue, blood and CSF
Intracranial Pressure (ICP) Definition and values
Tension within the cranial fault.
Normal: 5–15 mmHg for a supine adult
Abnormal: >20 mmHg
Name the pressure–volume relationship in the head
and its components
Monro-Kellie hypothesis
ICP - CSF, blood, and brain tissue Vol - cerebral perfusion pressure (CPP)
Volume compensation: total intracranial
volume does not change
What does the brain do when ICP increases?
- Less blood to head
- CSF into the spinal canal
- increasing absorption / decreasing production of CSF
Define Cerebral auto regulation
and equation for cerebral perfusion pressure
Blood flow regulation to compensate for changes in perfusion pressure
CPP = MAP - ICP
Result of CPP < 50 mmHg and CPP < 30 mmHg
- Cerebral ischaemia and neuronal death
- Life incompatibility
How do you calculate Cerebral Perfusion Pressure?
CPP = MAP – ICP
Name the two major consequences of increased ICP
- brain shifts
- brain ischaemia
What causes raised ICP?
- Trauma
- Cerebral oedema
- Space occupying lesion, ie tumour
- Metabolic, for eg, diabetic ketoacidosis
Name the 4 types of Cerebral Oedema
- Vasogenic
- Cytotoxic
- Ischaemic
- Autogestion
Clinical manifestations of raised ICP
Increasing T and BP
Decreasing Pulse and RR
Late clinical manifestations of raised ICP
High consciousness deterioration Increased Pulse P Irregular shallow, slow breathing Slow pulse High T
Describe Decorticate Posturing
Arms flexed / bent inward on chest, hands clenched into fists, legs extended and feet turned inward
Describe Decerebrate Posturing
Head arched back, arms
extended by the sides, and legs extended
Define Brain Death
Complete and irreversible loss of brain function
including involuntary activity necessary to sustain life