2536- CNS & ICP Lecture
CNS- Regions of the Brain
Cerebrum: Gray (cortex) and white matter
Cerebellum
Brain stem
CNS- Meningitis
inflammation of the meneges: DAP
usually bacterial: CSF LP Results- cloudy
can also be viral: CSF LP Results-clear
+ve kurn sign: inability to strecth your knees
CNS- Encphalitis
Inflammation of the brain parenchyma
usually a viral cause
symptoms: malaise, classic triad
CNS- Brain Abcess
necrosis with inflammation
bright ring with dark centre
increased ICP whn lying supine
usually bacterial cause
surgery drainage
CNS- Cerebral Bloodflow
Internal coratoid anterior arteries: Cerebrum
Verterbral posterior arteries: brain stem, cerebellum and posterior cerebrum
20% of CO is produced
FORM THE CIRCLE OF WILLIS
ICP- CSF
produced by the choroid plexus and used for metabolic exchange, Excretory veichle
Bathes in the brain and spinal cord untill its absorbed back into the veins
ICP- Cerebral Perfusion Pressure (CPP)
=MAP (blood in) -ICP (blood out)
60-80mmhg, based on pt baseline
Importance of CPP is that it helps prevent hyperperfusion: edema
and hypoperfusion; ischemia
ICP- Increased ICP
pressure exterted within the confines of the skull
ICP range: below 20mmhg
increased ICP is greater than 20mmhg
+ve Macewens sign
ICP- Monroe-Kellie Doctrine
Intracranial contents: Brain mass, CSF, Blood
if there is an increase in one, the other two attempt to decrease to maintain ICP
Cushings Triad
Hypertention
Bradycardia
Irregular respiration
ICP-AutoRegulation Significance
Maintains steady slow despite physio changes by the constricting and dialting of arteries
ICP- Diagnosis
CT- Edema, compression of ventricles
MRI- enlarged ventricles
LP- CSF measurement: X>20mmhg
ICP- Bed elevation Significance
30 degrees or higher because it facilitates venous drainage and avoids jugular compression
ICP- Surgical interventions
Decompressive crainectomy: LAST RESORT, remove portion of the skull and allow brain to swell
Shunts: diverts CSF to other parts of the body
ICP- CSF Drainage
EVD: drains CSF
LP: carries risk of herniation
ICP- effects of ventilation
Hyperventiliation will cass hypocapnia which will decrease ICP: If excessive can cause brain ischemia
Hypoventilation will cause hypercapia which will increase ICP: can then worsen Increased ICP, brain injury,etc
ICP Pharm- Osmotic Diuretics
reduce cerbral edema by creating gradient that draws fluid from brain tissue and into venous drainage system
MANNITOL: can cause renal failure
HYPERTONIC SALINE: can cause fluid shifts
ICP Pharm- Steroids
effective with brain tumours and stabalaizes blood barrier
DEXAMETHOSONE : Not recomended for TBI pt
Check BG regulary and for signs of infection
Dose Tapering
ICP Pharm- Barbiturates
Refractory reasons
INDUCES COMA
Narrow therapuetic window
ICP Pharm- Anti seizure meds
can mask other symptoms
use with caution
ICP Pharm- Paralyzing agents
paralysis of the lungs
intubation required
ICP Pharm- AB
If increased ICP is due to infection