Traumatic Brain Injury and ICP Management
5-15
Normal ICP (mmHg)
Treat if above 20-22
60-70
CPP Target (mmHg)
Cerebral perfusion pressure goal
3-15
GCS Range
Eye + Verbal + Motor
GCS and ICP Monitoring
The Glasgow Coma Scale measures Eye opening (1-4), Verbal response (1-5), and Motor response (1-6). A GCS of 8 or below generally warrants intubation. ICP monitoring is indicated for GCS ≤8 with abnormal CT findings.
Cushing's triad is a LATE sign. Earlier signs include headache, decreased LOC, vomiting. By the time you see the classic triad, you are behind.
ICP Management Tiers
HOB 30 degrees, head midline, avoid neck flexion, treat fever, adequate sedation and analgesia
Osmotic therapy (mannitol 0.25-1 g/kg or hypertonic saline 3%), CSF drainage if EVD present, moderate hyperventilation (PaCO2 30-35 temporarily)
High-dose barbiturate coma (pentobarbital), decompressive craniectomy, therapeutic hypothermia
Key Values to Memorize
Normal ICP 5-15 mmHg
Treat ICP >20-22
CPP goal 60-70
GCS ≤8 = intubate
Mannitol hold >320 osm
HOB 30 degrees always
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Practice CCRN QuestionsExam Traps
CPP = MAP minus ICP is the formula you must know cold
If ICP rises, CPP drops unless MAP also rises. If CPP falls too low, the brain is not being perfused. The exam will give you MAP and ICP and expect you to calculate CPP. A CPP below 60 means the brain is in danger.
Cushing triad is a LATE sign of herniation
Hypertension with widening pulse pressure, bradycardia, and irregular respirations indicate brainstem compression. By the time you see Cushing triad, herniation may already be occurring. Earlier signs include headache, decreased LOC, vomiting, and unilateral pupil dilation.
Hold mannitol if serum osmolality exceeds 320 mOsm/kg
Mannitol is an osmotic diuretic that draws water out of brain tissue. But if osmolality is already high, giving more mannitol can cause renal failure and paradoxical cerebral edema. Check osmolality before each dose.
Hypertonic saline is increasingly preferred over mannitol
Both reduce ICP by osmotic mechanisms. Hypertonic saline (3% or 23.4%) does not cause the diuresis that mannitol does, making it safer in hypotensive patients. It also does not require the osmolality hold threshold that mannitol does.
CPP Formula
CPP = MAP minus ICP. If ICP goes up and MAP stays the same, CPP drops and the brain starves. Protect that CPP.
Tier 1 ICP Management
HOB 30 degrees. Head midline. Avoid neck flexion. Prevent fever. These cost nothing and should be done for every neuro patient.
The skull is a closed, rigid box. Unlike the abdomen, it cannot expand. The brain, blood, and CSF all share this fixed space. When one component increases in volume, something else must decrease or pressure rises (Monro-Kellie doctrine).
After a TBI, the brain swells like an inflating balloon inside the box. As the balloon gets bigger, pressure (ICP) goes up. The brain gets squeezed against the skull and eventually pushes downward through the foramen magnum (herniation).
CPP is the pressure that pushes blood INTO the brain. If the balloon (ICP) squeezes too hard, blood cannot get in. You need enough MAP to overcome the ICP. That is why CPP = MAP minus ICP. Keep CPP above 60-70.
Osmotic therapy (mannitol, hypertonic saline) pulls water out of the balloon. HOB elevation and head midline help blood drain out of the box. Sedation reduces metabolic demand. All of these shrink the balloon.
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