Flashcards in Neurointensive Care and Encephalopathies ✅ Deck (89)
What is the purpose of neurointensive care?
Prevent further damage (secondary injury) to the brain and allow best possible recovery from primary insult
What is the physiological basis for neurointensive care?
How does the Monro-Kellie doctrine see the head?
As a ‘rigid box’ with a fixed volume
What is the fixed volume of the head made up of?
- Arterial and venous blood
What can cause expansion of the brain volume?
- Cerebral oedema
- ‘New matter’ occupying space
What ‘new matter’ can occupy space in the brain?
- Expanding haematoma
- Obstructive hydrocephalus
How can raised pressure in the head be compensated for?
Reduction in amount of CSF or venous blood
How good is the compensation mechanism of reduction in amount of CSF or venous blood?
Limited capacity for compensation, and will still be some increased in ICP towards 20mmHg
What is the normal ICP?
What happens when the capacity of the head to compensate for increased pressure fails?
The system becomes non-compliant and further small increases in volume will produce rapid rises in pressure
What is required due to the rapid increase in ICP when compensation mechanisms fail?
What management might be used in raised ICP?
- Definitive surgery
What is the timeframe for performing definitive therapy to manage raised ICP?
Within 4-6 hours
What is the aim of definitive surgery to manage raised ICP?
Remove expanding intracranial mass lesions, e.g. haematoma
What happens once ICP exceeds mean arterial pressure (MAP)?
Cerebral perfusion becomes critically impaired, and hypoxic-brain injury may occur
What can further increases in ICP past MAP lead to?
- Transtentorial herniation
- Uncus or cerebellar tonsillar herniation
What part of the brain is affected in transtentorial herniation?
The innermost part of the temporal lobe
What does the uncus or cerebellar tonsillar herniation occur through?
The foramen magnum
What does brain herniation (transtentorial, uncus, or cerebellar tonsillar) lead to?
Brainstem compression and ultimately brain death
What is tonsillar herniation also known as?
What happens in tonsillar herniation?
The cerebellar tonsils move downward through the foramen magnum, causing compression of the lower brainstem and upper cervical spinal cord
What does increased pressure on the brainstem result in?
Dysfunction of the centres responsible for controlling respiratory and cardiac function
What investigation is required in all patients with encephalopathy?
Why do all patients with encephalopathy require neuroimaging?
To make an assessment of ICP
What monitoring should be considered in patients with encephalopathy?
How is ICP monitoring usually done?
Neurosurgical insertion of a fine bore catheter into the substance of the brain through a small burr hole
When is ICP monitoring the standard of care?
In traumatic brain injury requiring neurointensive care
What is the advantage of ICP monitoring?
Allows accurate assessment of cerebral perfusion pressure (CPP)
How is CPP calculated?
MAP - ICP