Clinical Aspects of Cerebral Perfusion and ICP Flashcards
What does GCS stand for?
Glasgow coma scale
What does the GCS look at?
Eye response
Verbal response
Motor response
What is the scoring of the GCS?
Best eye response - open spontaneously - 4 - open to verbal command - 3 - open to pain - 2 - does not open eyes - 1 Best verbal response - orientated - 5 - confused speech - 4 - inappropriate words - 3 - incomprehensible sounds - 2 - no speech - 1 Best motor response - obeys commands - 6 - localises to pain - 5 - Normal flexion to pain - 4 - abnormal flexion to pain - 3 - Extension to pain - 2 - no movement
What is the total score of the GCS?
15
What is the eye response of the GCS marked out of?
4
What is the verbal response of the GCS marked out of?
5
What is the motor response of the GCS marked out of?
6
What does disruption of the BBB lead to?
Increased ECF (vasogenic oedema)
Membrane failure
- influx of Ca - cellular swelling (cytotoxic oedema)
Influx of inflammatory mediators
What does BBB stand for?
Blood brain barrier
What are the secondary effects of raised ICP?
Anatomical - herniation syndromes
Cellular - decreased cerebral perfusion
What % of CO does the adult brain receive?
15%
Does the brain have a high O2 consumption?
Yes
What regulates cerebral blood flow?
Autoregulation (myogenic)
Cerebral metabolism
CO2 and O2
Neurohumoral factors
Examples of herniation syndromes
Subfalcine herniation
Uncal herniation
Foramen magnum herniation
What does a subfalcine herniation affect?
Medial motor cortex
What does uncal herniation affect?
IIIrd CN
Ipsilateral corticospinal tracts
What does a foramen magnum herniation affect?
Brain stem centres
On intubation, what does the anesthetist briefly do to help the patient control his ICP?
Hyperventilate them
What is normal PaO2?
80 - 100mmHg
What is normal PaCO2?
35 - 45mmHg
What interventions can neurosurgeons use to reduce ICP?
Craniotomy and evacuation of clot
External ventricular drainage
Decompressive craniotomy
What does the Munro-Kellie Doctrine consist of?
Fixed volume; Brain/CSF/Blood
V(CSF) + V(blood) + V(brain) + V(other) = V(intracranial space) = constant
What is the normal MAP?
90mmHg
What is the normal ICP?
5 - 15 mmHg
What does the CPP =?
MAP - ICP
What does MAP =?
Diastolic BP + 1/3 pulse pressure
What is the normal CPP value?
80mmHg
What medical management can be used in ITU to reduce ICP?
Head position - 30 degrees head up Nothing to impede venous drainage CO2 maintained in a low normal range Intermittent boluses of mannitol when ICP raised Fully sedated and paralysed
What can ICP be eventually controlled by after everything else?
Deep sedation with thopentone
Treatment of neuroepileptic malignant syndrome
Bromocriptine (dopamine agonist)
When assessing the GCS, what must be done?
The BEST response from both sides
Pneumonic to remember the features of wernickes encephalopathy
CAN OPEN Confusion Ataxia Nystagmus Opthalmoplegia Peripheral neuropathy
Cause of wernickes encephalopathy
Thiamine (Vit B12) deficiency
Who is wernickes encephalopathy commonly seen in?
Alcoholics
Causes of wernickes encephalopathy
Alcoholics
Persistent vomiting
Stomach cancer
Dietary deficiency
Classic triad of wernickes
- Opthlamoplegia/nystagmus
- Ataxia
- Confusion
Features of wernickes
Opthalmoplegia Nystagmus Ataxia Confusion - altered GCS Peripheral sensory neuropathy
Investigations of wernickes encephalopathy
Decreased red cell transketolase
MRI
Treatment of wernickes
Urgent replacement of thiamine
What may develop if don’t treat wernickes?
Korasskofs syndrome
Features of korasskofs
Confabulation
Amnesia (anterograde and retrograde)
Definition of confabulation
Make up stories in compensation for lost memories
