Head injuries & ICP

Question 1

Normal range for ICP in the brain

Answer 1

5-15 mmHg

Question 2

What is cerebral perfusion pressure (CPP)?

Answer 2

the pressure needed to ensure blood flow to the brain

Question 3

Normal range for CPP

Answer 3

60-100 mmHg

Question 4

Formula to calculate CPP

Answer 4

MAP - ICP= CPP

Question 5

What is compliance?

Answer 5

the expandability of the brain

Question 6

Most sensitive indicator for evaluating pt’s neuro state

Answer 6

Level of consciousness (LOC)

Question 7

Oculomotor nerve

Answer 7

Cranial nerve III

Question 8

What is the significance of the halo sign?

Answer 8

tests the fluid coming from nose or ear for CSF

Question 9

How is halo sign tested?

Answer 9

have the fluid drip onto gauze.

If yellowish ring encircles the blood, CSF is present.

Question 10

Purpose of the GCS

Answer 10

to assess LOC

Question 11

3 areas assessed for GCS

Answer 11

• speech
• obey commands
• open eyes

Question 12

Craniectomy

Answer 12

excision to cut away bone flap from skull

Question 13

Burr hole

Answer 13

hole drilled into skull to remove localized fluid and blood from under dura

Question 14

Craniotomy

Answer 14

opening into skull with removal of bone flap and opening the dura

Question 15

Autoregulation of cerebral blood flow

Answer 15

automatic adjustment in diameter of cerebral blood vessels by the brain to maintain constant blood flow during changes in arterial BP

Question 16

What is stage 1 of cerebral blood flow (CBF)?

Answer 16

Stage 1

• High compliance.
• the brain is in total compensation, with accommodation and autoregulation intact.

Question 17

True or False:

An increase in volume does NOT increase the ICP

Answer 17

True

Question 18

What is stage 2 of CBF?

Answer 18

Stage 2

-the compliance is beginning to decrease, and increase in volume places the pt at risk for high ICP and secondary injury

Question 19

What is stage 3 of CBF?

Answer 19

Stage 3
-significant reduction in compliance

• any small addition to volume causes a great increase in ICP
• compensatory mechanisms fail, there is a loss of autoregulation, and the pt exhibits manifestations of increased ICP

Question 20

What is stage 4 of CBF?

Answer 20

Stage 4
-ICP rises to lethal levels with little increase in volume.

-herniation occurs as the brain tissue is forcibly shifted from the compartment of greater pressure to a compartment of lesser pressure

Question 21

Can the brain stem die if herniation continues?

Answer 21

Yes, due to increased pressure on brain stem.

Question 22

True or False:

Cushing’s triad is not an emergency

Answer 22

False. It is a neurological emergency

Question 23

What is Cushing’s triad?

Answer 23

when the autoregulation is lost, the body attempts to maintain cerebral perfusion by increasing systolic BP, but decomposition happens.

Question 24

Patient’s response to Cushing’s triad?

Answer 24

• systolic HTN with widening pulse pressure
• bradycardia
• full bounding pulse
• altered respirations
• noticable change in body temp (can go up or down)

Question 25

True or False: O2 and CO2 affect cerebral blood vessel tone

Answer 25

TRUE.

Question 26

High CO2 and cerebral blood flow

Answer 26

- relaxes smooth muscles - dilates vessels - decreases cerebrovascular resistance - increases CBF

Question 27

Low CO2 and cerebral blood flow

Answer 27

- constricts vessels - increases cerebrovascular resistance - decreases CBF

Question 28

What happens if cranial nerve III is compressed?

Answer 28

- dilation of pupil on same side (ipsilateral) as mass or lesion - sluggish or no response to light - inability to move eye upward - ptosis of eyelid

Question 29

Decorticate posturing (flexor)

Answer 29

internal rotation and adduction of the arms -result of interruption of voluntary motor tracts in cerebral cortex

Question 30

Decerebrate posturing (extensor)

Answer 30

arms are stiffly extended, adducted, and hyperpronated - result from disruption of motor fibers in mid-brain and brain stem * may indicate more serious damage

Question 31

Nursing interventions for ICP

Answer 31

- HOB 30 degrees or higher - head in neutral position - intubation/mechanical ventilation - ICP and cerebral O2 monitoring - maintain > 100 mmHg PaO2 - maintain fluid balance, assess osmolality - maintain systolic arterial pressure 100-160 mmHg - reduce cerebral metabolism (high dose barbiturates)

Question 32

Drug therapy for ICP

Answer 32

- osmotic diuretic (mannitol) - hypertonic saline - antiseizure meds (phenytoin) - corticosteroids for brain tumors, bacterial meningitis - H2 receptor antagonist or proton pump inhibitors to prevent GI ulcers and bleeding

Question 33

Epidural hematoma

Answer 33

- bleeding between dura and inner surface of skull - EMERGENCY! - venous or arterial

Question 34

Subdural hematoma

Answer 34

- bleeding between dura and arachnoid layer of meninges | - results from injury to brain tissue and blood vessels

Question 35

Acute subdural hematoma

Answer 35

within 24-48 hours of injury

Question 36

Subacute subdural hematoma

Answer 36

within 48 hours-2 weeks of injury

Question 37

Chronic subdural hematoma

Answer 37

within weeks or months, usually >20 days

Question 38

Intracranial hematoma

Answer 38

- occurs from bleeding within brain tissue - usually within frontal and temporal lobes -approximately 16% of head injuries

Question 39

How much of the brain is made up of glucose and where does the glucose come from?

Answer 39

25% and cardiac output

Question 40

How much of the brain is made up of O2 and where does the O2 come from?

Answer 40

20% and cardiac output

Question 41

Is it better or worse for a patient with a head injury to have a high b/p?

Answer 41

Better! Increased b/p can help offset the ICP. Ideally you want the patient to have a MAP of 140-150. Increased b/p and increased ICP means the brain is getting blood flow.

Question 42

What MAP is too high and considered dangerous for a head injury patient?

Answer 42

165 and higher is TOO high

Question 43

If a patient with a head injury has a low ICP and a low b/p what should you do?

Answer 43

Notify the provider

Question 44

The brain can tolerate a low MAP until it reaches what value?

Answer 44

A MAP below 50 will cause ischemia | A MAP below 30 results in cell death

Question 45

The eyes are the _______ to the brain

Answer 45

Window Checking the patient's eyes is imperative if a patient comes in with a head injury. If a patient comes in with a head injury and their pupils are extremely dilated or non-responsive that is NOT good. This means the oculomotor nerve is compressed. NOTE: Compression will happen on the same side as the injury.

Question 46

Increased CO2 causes what s/s?

Answer 46

Confusion and altered mental status

Question 47

What type of medication should be avoided in patients with head injuries?

Answer 47

Sedatives! Sedatives cause a decrease in LOC and can impair ability to evaluate the patient

Question 48

What drug class is mannitol?

Answer 48

Osmotic diuretic

Question 49

How does mannitol work in the body?

Answer 49

- Medication works via osmosis - The medication will pull fluid from the brain tissue and deposit the fluid into the bloodstream. This will help the ICP to decrease and the b/p to increase

Question 50

What IV fluid works like mannitol?

Answer 50

3% normal saline

Question 51

A patient with a head injury is at increased risk for what?

Answer 51

Seizures

Question 52

What are diagnostic tests for head injury patients?

Answer 52

CT scan | MRI

Question 53

What is a ventriculostomy?

Answer 53

The "gold standard" method used to measure ICP A ventriculostomy also allows for CSF removal or sampling