Increased ICP

Question 1

normal icp values

Answer 1

adults 4-15 mmhg
children 3-7 mmhg
infants 1.5-6 mmhg

increased >20 cmh2o / >15 mmhg

Question 2

monro kellie doctrine

Answer 2

brain, csf, and blood are incompressible
change in volume -> damage to others
inc. brain vol -> dec. blood volume -> dec CSF

Question 3

compliance vs elastance

Answer 3

compliance: quality of distensibility available within intracranial contents that enable them to adapt to lesions
elastance: resistance of contents to the expansion of mass

Question 4

defect and presentation of subfalcine or cingulate herniation

Answer 4

defect: compression of internal cerebral vein and anterior cerebral artery
presentation: contralateral hemiparesis

Question 5

defect and resentation of central transtentorial herniation

Answer 5

page 2 (4 items)

Question 6

defect in uncal herniation

Answer 6

compression of midbrain, 3rd nerve, pca

Question 7

defect and presentation of tonsillar herniation

Answer 7

page 3

Question 8

normal cpp

Answer 8

60-80 mmhg

< 50 cerebral ischemia
< 30 brain death

Question 9

cbf values

Answer 9

n: 50 ml/min/100g

10-15 ml/100g/min reversible ischemia
<10-15 irreversible ischemia

Question 10

normal map

Answer 10

50-150 mmhg

> 150 increase cbf, constricted
<50 decreased cbf, dilated

Question 11

normal hourly and daily rate of csf production

Answer 11

20 ml/hr

450-500 ml/day

Question 12

triad in increased icp

Answer 12

headache*
vomiting
papilledema (most reliable sign, fundoscopy)

Question 13

t/f papilledema does not affect visual acuity

Answer 13

true

Question 14

vital signs in increased icp

Answer 14

triad: hpn, bradycardia, bradypnea

pain, agitation, blood loss -> paradoxic tachycardia

Question 15

focal deficits in increased icp

Answer 15

decreased consciousness and mental status
cardiac dysrhtymias
pupillary abnormalities
bilateral rectus palsy

icp >40-50 mmhg -> dec blood flow -> global ischemiai -> dec consciousness

Question 16

types of brain swelling

Answer 16

cytotoxic
vasogenic
hydrocephalic
hydrostatic

Question 17

what is cytotoxic edema

Answer 17

excess fluid in intracellular space
involves gray and white matter

responsive to osmolar therapy

Question 18

what is vasogenic edema

Answer 18

excess fluid in interstitial space
white matter edema (gray sparing)
disruption of bbb and diffusion of water

responsive to glucocorticoids

Question 19

what is hydrocephalic edema

Answer 19

transependymal seepage of csf into interstitium

intact bbb

Question 20

what is hydrostatic edema

Answer 20

malignant hypertension -> disrupt bbb –> transvascular diffusion into interstitial space

occurs in posterior circulation

Question 21

causes of inc venous pressure

Answer 21

sagittal sinus thrombosis
heart failure
obstruction of mediastinal or jugular veins
pseudotumor cerebri

Question 22

mechanisms of csf flow obstruction

Answer 22

ventricles or base of brain = hydrocephalus

extensive meningeal disease (meningitis, subarachnoid hemorrhage, leptomeningeal carcinomatosis)

Question 23

t/f if the csf block is at the cerebral convexities and SSS, ventricles remain in size or slightly enlarge only

Answer 23

true

Question 24

causes of csf expansion

Answer 24

meningitis, subarachnoid hemorrhage, choroid plexus tumor

Question 25

hypertonic solutions for management

Answer 25

``` mannitol = osmotic dehydration and diuretic effect hypertonic saline hypertonic lactate furosemide glycerol ```

Question 26

use of steroids for management

Answer 26

effective for vasogenic edema but not cytotoxic edema

Question 27

principle of head elevation

Answer 27

30 deg = dec intrathoracic pressure and inc jugular vein drainage = dec icp by 3-4 mmhg dec in icp = dec cpp --> ISCHEMIA

Question 28

principle of hyperventilation

Answer 28

rapidly reduces icp by reflex vasoconstriction due to hypocapnic csf alkalosis reduces icp in 10 min, peak effect at 20-40 mins

Question 29

target paco2 in hyperventilation

Answer 29

35 mmhg patients in icp crisis or herniation = 28-32 mmhg NOT <28 mmhg

Question 30

use of sedation in management

Answer 30

pain = narcotics agitation = short acting sedatives coughing at et tube = sedatives shivering = narcotics

Question 31

principle of metabolic suppression

Answer 31

suppresses brain metabolism by hypothermia and general anes --> reduced blood flow pentobarbital or propofol

Question 32

there is mortality benefit in duraplasty for patients ___ age with malignant mca if surgery is done within ___ hrs

Answer 32

<60 yo within 24-48h

Question 33

indications for icp monitoring

Answer 33

``` gcs <8 and abnormal ct OR normal ct with (2/3): - >40 yo - unilateral or bilateral posturing -systolic bp < 90 ```

Question 34

gold standard for icp monitoring

Answer 34

extra ventricular drain - icp monitor - intermittent drainage