Increased ICP Flashcards
normal icp values
adults 4-15 mmhg
children 3-7 mmhg
infants 1.5-6 mmhg
increased >20 cmh2o / >15 mmhg
monro kellie doctrine
brain, csf, and blood are incompressible
change in volume -> damage to others
inc. brain vol -> dec. blood volume -> dec CSF
compliance vs elastance
compliance: quality of distensibility available within intracranial contents that enable them to adapt to lesions
elastance: resistance of contents to the expansion of mass
defect and presentation of subfalcine or cingulate herniation
defect: compression of internal cerebral vein and anterior cerebral artery
presentation: contralateral hemiparesis
defect and resentation of central transtentorial herniation
page 2 (4 items)
defect in uncal herniation
compression of midbrain, 3rd nerve, pca
defect and presentation of tonsillar herniation
page 3
normal cpp
60-80 mmhg
< 50 cerebral ischemia
< 30 brain death
cbf values
n: 50 ml/min/100g
10-15 ml/100g/min reversible ischemia
<10-15 irreversible ischemia
normal map
50-150 mmhg
> 150 increase cbf, constricted
<50 decreased cbf, dilated
normal hourly and daily rate of csf production
20 ml/hr
450-500 ml/day
triad in increased icp
headache*
vomiting
papilledema (most reliable sign, fundoscopy)
t/f papilledema does not affect visual acuity
true
vital signs in increased icp
triad: hpn, bradycardia, bradypnea
pain, agitation, blood loss -> paradoxic tachycardia
focal deficits in increased icp
decreased consciousness and mental status
cardiac dysrhtymias
pupillary abnormalities
bilateral rectus palsy
icp >40-50 mmhg -> dec blood flow -> global ischemiai -> dec consciousness
types of brain swelling
cytotoxic
vasogenic
hydrocephalic
hydrostatic
what is cytotoxic edema
excess fluid in intracellular space
involves gray and white matter
responsive to osmolar therapy
what is vasogenic edema
excess fluid in interstitial space
white matter edema (gray sparing)
disruption of bbb and diffusion of water
responsive to glucocorticoids
what is hydrocephalic edema
transependymal seepage of csf into interstitium
intact bbb
what is hydrostatic edema
malignant hypertension -> disrupt bbb –> transvascular diffusion into interstitial space
occurs in posterior circulation
causes of inc venous pressure
sagittal sinus thrombosis
heart failure
obstruction of mediastinal or jugular veins
pseudotumor cerebri
mechanisms of csf flow obstruction
ventricles or base of brain = hydrocephalus
extensive meningeal disease (meningitis, subarachnoid hemorrhage, leptomeningeal carcinomatosis)
t/f if the csf block is at the cerebral convexities and SSS, ventricles remain in size or slightly enlarge only
true
causes of csf expansion
meningitis, subarachnoid hemorrhage, choroid plexus tumor
hypertonic solutions for management
mannitol = osmotic dehydration and diuretic effect hypertonic saline hypertonic lactate furosemide glycerol
use of steroids for management
effective for vasogenic edema but not cytotoxic edema
principle of head elevation
30 deg = dec intrathoracic pressure and inc jugular vein drainage = dec icp by 3-4 mmhg
dec in icp = dec cpp –> ISCHEMIA
principle of hyperventilation
rapidly reduces icp by reflex vasoconstriction due to hypocapnic csf alkalosis
reduces icp in 10 min, peak effect at 20-40 mins
target paco2 in hyperventilation
35 mmhg
patients in icp crisis or herniation = 28-32 mmhg
NOT <28 mmhg
use of sedation in management
pain = narcotics
agitation = short acting sedatives
coughing at et tube = sedatives
shivering = narcotics
principle of metabolic suppression
suppresses brain metabolism by hypothermia and general anes –> reduced blood flow
pentobarbital or propofol
there is mortality benefit in duraplasty for patients ___ age with malignant mca if surgery is done within ___ hrs
<60 yo
within 24-48h
indications for icp monitoring
gcs <8 and abnormal ct OR normal ct with (2/3): - >40 yo - unilateral or bilateral posturing -systolic bp < 90
gold standard for icp monitoring
extra ventricular drain
- icp monitor
- intermittent drainage
