Head Injury Flashcards
How common is head injury?
it is the leading cause of death in UK population aged less than 40yrs
What is the difference between primary and secondary brain injury
Primary- injury to brain tissue occurs at the time of injury
Seconday- occurs as a consequence of the injury ie it is partly preventable
Describe the pathophysiology of head injury
Injury –> release of excitatory amino acids (glutamate, aspartate) –> binding to NMDA receptors –> releas of intrecellular calcium, activation of phospholipases, breakdown of cell membrane, cell swelling, activation of apoptosis
How does a head injury then lead on to result in secondary brain injury
Loss of BBB, leucocyte infiltration = INFLAMMATION
Loss of cerebral autoregulation of BP = ISCHAEMIA
loss of cerebral autoregulation of blood flow- metabolic de-coupling- even more ischaemia causing further brain oedema
What is CPP
CCP= cerebral perfusion pressure
CPP = MAP - ICP
where map is mean arterial pressure and ICP is intracranial pressure
What is the aim CPP
more than 60mmHg after head injury
what is a normal adult ICP
9-11mmHg (12-15cm H2O)
what are the two typs of head injury
open ie penetrating
closed ie acceleration/deceleration/rotation
What can be a sign of anterior cranial fossa fracture
‘racoon’ or ‘panda eyes’
what is a sign of middle cranial fossa fracture
battle sign over mastoid area
what focal signs may occur
lateralising motor signs
pupillary responses to light impaired due to third nerve palsy
what is used to assess a patient with a head injury
Glasgow coma scale
what are the three parts of the GCS
Eye opening
verbal response
best motor response
How is a GCS given
score between three and fifteen Eyeopening - spontaneously =4 to command =3 to pain=2 none = 1 Verbal - orientated= 5 confused = 4 inappropriate words= 3 sounds=2 none=1 Motor obeys commands= 6 localises pain=5 flexes to pain=4 abnormal flexion=3 extension=2 none=1
what is the definition of a coma
do not open eyes
do not obey commands
do not speak
ie GCS less than 8
how can people die from head injury
hypoxia
hypotensions
raised ICP
how much of your cardiac output, oxygen and glucose does your brain use
15 percent of cardiac output
20 percent of circulating oxygen
12 percent of carried glucose
how soon will neuronal damage occur after circulatory arrest
five mins
when should you get a ct scan in head trauma
Any patient with a skull fracture
or with a GCS less than fifteen ie not orientated
or with focal neuro signs
or on warfarin/anticoagulants
from outside to inside what types of traumatic brain bleed can you get
Extradural haematoma Subdural '' Traumatic subarachnoid haemorrhage Intracerebral contusion Intracerebral haematoma Intraventricular haemorrhage
what is map
(2 x diastolic + systolic)/3 = MAP
How is a head injury managed in intensive care
Sedation - reduces, cerebral metabolic rate, cerebral blood flow and ICP
Ventilate- maintain oxygen and normocapnia
BP- manipulate to give CPP of more than 60
Glucose and temp maintanence
What are normal oxygen levels
p02 13-15kPa
what is normal co2 levels
4-4.5 kPa
