acute intracranial problems Flashcards
CSF circulation
- 4 ventricles
- subarachnoid space
CSF function
cushioning for brain and spinal cord
CSF formation
choroid plexus in the ventricles
CSF absorption
arachnoid villi
CSF resemblence
ultra filtrate of blood
ICP
- hydrostatic force measured in the brain CSF compartment
- balance of brain tissue, blood, & CSF
factors that influence ICP
- arterial and venous pressure
- intra abd and intra thoracic pressure
- posture
- temperature
- blood gases/CO2
CBF (cerebral blood flow)
- amount of blood in mLs passing through 100g of brain tissue in 1 min
- 50mL/min/100g of brain tissue
- white matter: 25mL/min
- gray matter: 75mL/min
factors that influence CBF
- decreased O2
- increased CO2, pH
normal ICP
5-15 mmHg
normal CPP
60-100 mmHg
normal MAP
70-105 mmHg
-perfusion
MAP calculation
[SBP + 2(DBP)] / 3
CPP calculation
MAP-ICP
flow x resistance
CPP
-pressure needed to ensure blood flow to the brain
-
indications of monitoring ICP
- neurological insults
- patients with GCS of 8 or less
- abnormal CT or MRI
methods of measuring ICP
- *ventriculostomy (also drains CSF)
- fiberoptic catheter (in brain tissue)
- subarachnoid bolt or screw
increased ICP
- life threatening (above 20mmHG)
- diminishes CPP
- increased risks of brain ischemia and infarction
- poor prognosis
causes of increased ICP
- mass lesion
- cerebral edema
increased ICP compensation
- altered CSF absorption or production
- changes in intracranial volume
- brain tissue distention or compression
LOC in increased ICP
- most sensible and reliable indicator of neurological status
- EEG
VS in increased ICP
- increased temp
- Cushing’s Triad
- systolic HTN with widening pulse pressure
- bradycardia
- full and bounding pulse
- irregular respirations
ocular s/s in increased ICP
- ipsilateral pupil dilation
- sluggish or no response to light
- inability to move the eye upward
- ptosis of the eyelid
- blurred vision
- diplopia
- changes in extra ocular eye mvmt
- papilledema
motor function in increased ICP
- contralateral hemiparesis or hemiplegia
- painful stimuli: localize or w/d
- noxious stimuli: decorticate posturing and decerebrate posturing
other s/s of increased ICP
- HA worse in the morning
- vomiting usually without nausea, sometimes projectile
complications of increased ICP
- tentorial (central) herniation
- uncal herniation
- cingulate herniation
tentorial herniation
separates the cerebellum and cerebrum
cingulate herniation
between cerebral hemispheres
mgmt of increased ICP
- surgery
- drug tx
- nutritional tx
drug tx in increased ICP
- Mannitol (osmotic diuretics)
- 0.9NS (hypertonic)
- dexamethasone
- pentobarbital
- acetaminophen
- phenytoin
- propofol
low Na in increased ICP
brain swelling
Cheyne-Stokes
cycles of hyperventilation and apnea
central neurogenic hyperventilation
sustained, regular rapid and deep breathing
apneustic breathing
prolonged inspiratory phase or pauses alternating with expiratory pauses
cluster breathing
clusters of breaths follow each other with irregular pauses between
ataxic breathing
- completely irregular with some breaths deeps and some shallow
- random, irregular pauses, slow rate
