What is ICP?
- Intracranial pressure
- The pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue
What is the Monro-Kellie Hypothesis?
Increase in volume of one of intracranial component must be compensated by decrease in one or more of other components so that volume remains fixed
What is normal intracranial pressure?
- 5-15 mmHg
- Greater than 20mmHg must be treated
How to measure intracranial pressure?
With a intraventricular catheter
What is cerebral blood flow?
Amount of blood that passes through the brain at any time
What is autoregulation?
The automatic alteration in the diameter of the cerebral blood flow to maintain a constant flow of blood to the brain during during systemic arterial pressure
What is CPP?
- Cerebral perfusion pressure
- Pressure to ensure blood flow to brain
What is normal CCP?
60-100mmHg
What does CCP of lower than 50mmHg indicate?
Ischaemia and neuronal death
What does CCP of lower than 30mmHg indicate?
Incompatibility with life
What is the nursing assessment of ICP and how frequently?
- Frequent neurological observations (30 mins-1 hr)
Why must a nurse complete frequent neurological observations for possible increased ICP?
Because a small change in volume can have dramatic effect on ICP
What can increased ICP?
- Anything that increased brain tissue, blood of CSF volume
- Cerebral oedema common factor
What causes cerebral oedema?
Mass lesion
- Head injuries
- Brain surgery
- cerebral infection
- Vascular insult
- Toxic or metabolic encephalopathic conditions
What are complications of increased ICP?
- Inadequate cerebral perfusion
- Cerebral oedema
- Cerebral herniation
What does herniation cause?
1) A potentially reversible process to become irreversible
2) Ischemia and oedema increase
3) Compression of brainstem and cranial nerves
4) Brain death
What is the progression of increased ICP?
- Cranial insult
- Tissue oedema
- Increased ICP
- Compression of blood vessels
- Decreased cerebral blood flow
- Decreased oxygen with death of brain cells
- Oedema around necrotic tissues
- Increased ICP with compression of brainstem and respiratory centre
- Accumulation of carbon dioxide
- Vasodilation - Increased ICP resulting from increased blood volume
- Death
What are clinical manifestation of increased ICP?
- Change in LOC
- Change in vital signs (Cushings triad=high bP with low diastolic, bradycardia, increased temp, erratic/decreased breathing)
- Ocular signs
- Decrease in motor function
- Headache
- Vomiting (projectile without nausea)
What do we assess in a neurological assessment?
- Glasgow coma scale
- Pupillary check for size and response
- Test strength and movement
- Vital signs
Checking for signs of Cushing’s triad which indicates severely increased ICP
What is a decorticate response?
Flexion of arms, wrists and fingers with adduction in upper extremities. Extension, internal rotation and plantar flexion in lower extremities
What is a decerebrate response?
All four extremities in rigid extension, with hyperpronation of forearms and plantar flexion of feet
What is opisthotonic posturing?
When the back becomes extremely arched
What are the types of head injuries?
- Scalp laceration
- Skull fractures
- Head trauma: diffuse or focal
What is a diffuse injury?
- Generalised
- Concussion
- Diffuse axonal injury
