Acute Brain Injury

Question 1

what is the key to managing head trauma cases

Answer 1

there are minimal effective interventions

many will resolve with TIME and you need to provide supportive care

Question 2

primary vs secondary injury after head trauma

Answer 2

primary: initial traumatic event causing parenchymal damage and vascular disruption

secondary: later stage effects of trauma leading to edema, inflammation, hypoxia, ischemia, neurotoxicity, and death

Question 3

what happens when brain volume increases (ex. with inflammation)

Answer 3

increases ICP leading to decreased CPP –> less O2 –> ischemia, necrosis, death

Question 4

cerebral blood flow (CBF)

Answer 4

amount of blood coming into and out of the cerebrum

depends on arterial inflow, venous outflow, and cerebrovascular resistance

Question 5

cerebral perfusion pressure (CPP)

Answer 5

CPP = MAP - ICP

if ICP increases –> CPP decreases –> less O2 supply to the brain

Question 6

volume buffering capacity of the brain

Answer 6

compensatory mechanisms of the intracranial contents to accommodate changes in volume without changing ICP

immediate: displaces CSF and blood OUT of the brain to decrease volume

long term: decrease ECF space, brain atrophy

Question 7

Cushing’s reflex

Answer 7

global response of the brain to dangerously high ICP

brain trauma –> increase ICP –> brain tries to increase arterial pressure via peripheral vasoconstriction to compensate –> hypertension –> reflex bradycardia

Question 8

clinical signs of intracerebral hemorrhage

Answer 8

cerebral signs
1. altered mentation
2. brainstem dysfunction
3. loss of motor control
4. abnormal posturing

Question 9

what should you always assume about head trauma patients prior to treatment

Answer 9

assume they are on the upper end of the ICP vs ICV curve - so small increases in volume will cause dramatic increases in pressure

Question 10

how does herniation happen

Answer 10

increased ICP –> creates large pressure gradient between intra and extracranial space –> brain herniates into lower pressure space

Question 11

what are the most common sites of herniation

Answer 11

1. foramen magnum: cerebellum herniates out the back of the skull
2. transtentorial: cerebrum herniates under the tentorium cerebelli into the space of the cerebellum causing MIDBRAIN damage
   - can lead to blown pupils (fixed and dilated) if becomes decerebrate

Question 12

what are the ways to measure ICP

Answer 12

exam - look for the clinical signs associated with high ICP

direct ICP monitors

imaging (rare)

Question 13

what is the goal of brain trauma treatment

Answer 13

maintain cerebral perfusion pressure by altering

• PaCO2
• MAP
• PaO2
• CMR
• drugs
• venous outflow

Question 14

PaCO2 effect on ICP and treatment

Answer 14

most significant factor controlling ICP/CBF

high PaCO2 –> vasodilation –> increased ICP

tx: ensure airway is patent
- keeps PaCO2 at physiologic levels

Question 15

MAP effect on ICP and treatment

Answer 15

brain has autoregulation mechanisms to keep pressure stable despite changes in MAP between 50-150 mmHg

tx: only treat HYPOTENSION with fluids
- do NOT treat hypertension (brain will resolve on its own)

Question 16

PaO2 effect on ICP and treatment

Answer 16

decreased PaO2 causes cerebral vasodilation –> increases CBF –> increases ICP

tx: use flow by O2

Question 17

cerebral metabolic activity (CMR) effect on ICP and treatment

Answer 17

metabolic activity causes production of metabolic byproducts that decrease pH and cause vasodilation –> increases ICP

high CMR –> fever, pain, seizures

tx: control fever, pain, seizures to lower metabolic activity of the brain

Question 18

what drugs should be avoided in head trauma cases

Answer 18

inhalant anesthetics
- causes vasodilation and increased ICP

Question 19

what drugs are good to use in head trauma cases

Answer 19

• barbituates
• propofol
• dexmedetomidine

Question 20

what are ways to ensure adequate venous outflow

Answer 20

1. keep head above the heart
2. avoid jugular compression (catheters, blood draws)

Question 21

what are the steps of treating a head trauma patient

Answer 21

1. stabilize
2. examine
3. determine severity
4. treat secondary injury
5. supportive therapy
6. diagnose and treat primary disease
7. determine prognosis

Question 22

what to do to stabilize patient

Answer 22

A: airway patency
B: breathing
C: compressions if needed

• immobilize if patient is showing signs of instability
• get a PCV, TP, BUN, glucose, and electrolytes
• get a history

Question 23

what should you examine in a head trauma patient

Answer 23

PE: check for bleeding, signs of CV status, and other external injuries

Neuro: localize the lesion

do NOT dilate the eyes - need to be able to assess pupils

Question 24

what are clinical signs of increased ICP

Answer 24

1. declining mentation
2. dilated and unresponsive pupils
3. CN dysfunction - decreased gag, absent physiologic nystagmus, declining motor
4. abnormal respiratory patterns
5. abnormal posturing (decerebrate, decerebellate, schiff-sherrington)

Question 25

how to treat secondary brain injury

Answer 25

1. fluids +/- glucose + electrolytes
2. O2 supplementation
3. elevate head and keep jugulars patent
4. treat seizures and hyper/hypothermia

Question 26

supportive care for head trauma patients

Answer 26

1. medications: antibiotics, antiemetics, anticonvulsants, pain control
   - do NOT use corticosteroids
2. nutrition
3. recumbent care
4. osmotic diuresis

Question 27

when should osmotic diuresis be used

Answer 27

severe cases OR if patient is rapidly declining

use mannitol or hypertonic saline

goal: expand plasma volume and reduce brain water content via osmotic pull

Question 28

prognosis for head trauma patients

Answer 28

poor: comatose for >48 hours or rapid deterioration

grave: fixed dilated pupils, decerebrate posture, apneustic respiration, flatline EEG or BAER