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RAISED ICP (Anatomy & Physiology:
brain and spinal column =…
RAISED ICP
Anatomy & Physiology:
brain and spinal column = surrounded by meninges: dura mater, arachnoid mater, pia mater
meninges separated by spaces: actual & potential epidural spaces; subdural space; subarachnoid space
Subarchanoid space surrounded by CSF
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CAUSES
4 mechanisms:
cerebral oedema (brain tissue)
vascular congestion/brain swelling
hydrocephalus
mass lesion
cerebrovascular (haemorrhage, thrombosis, infarct, secondary hydrocephalus
trauma (haematoma, brain swelling)
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Management
ABCDE assessment
Intubate/ventilate if GCS <8
ABG:
Aim PO2 13 (SpO2 <95%)
Avoid hyper + hypoventilation: aim pCO2 4-4.5
Avoid hypotension
Caution with treating hypertension: Cushing's triad (brain may depend on higher BP)
Detained neuro exam: fundoscopy, cranial nerve palsies, potential spinal cord injury)
:ambulance:Transfer to Neurological ICU
ICP monitoring:
pressure monitoring to maintina ICP less than 20-25mmHg
ensure CPP greater than 60mmHg
Avoid factors which worsen raised ICP
improving venous return (head positioning)
sedation
optimised ventilation
euvolaemia
normotension
avoid fever
avoid pain
avoid seizures
avoid anaemia
Mannitol to reduce cerebral oedema :question:
on Neuro Surgeon advice, only if evidence of coning. Temporising measure
Consider hypertonic NaCL to reduce brain oedema
Recognition
falling GCS
headache
vomiting
visual disturbance
+/- focal neurology
+/- papilloedema
+/- meningism
Cushing's Triad
critical compression of the structures controlling
cardiac & respiratory function
by displacement of the brainstem
:arrow_up: systolic BP w/ widened pulse pressure
:arrow_down: bradycardia
:twisted_rightwards_arrows: irregular breathing
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MECHANISM
"tension in the cranial vault" :skull:
skull a rigid container (see A&P):
brain tissue, cerebral blood and CS
if pressure from one component increase, the others compensate - reduce volume and subsequent rise in ICP: shifts of CSF, venous blood from cranium to compensate for the added volume
Compensation finite: once exhausted, pressure increases and brain may shift :arrow_right: brain herniation :skull_and_crossbones:
DEFINITION
raised ICP = final common pathway that leads to death/disability
potentially treatable
major consequences:
brain shift or brain ischaemia
Cerebral perfusion pressure (CPP) = MAP - ICP
noraml ICP 5-10mmHg
(varies over day)
acute rise: < 20-25mmHg <5 mins