Week 8 - Coma & Brain Death

Question 1

define coma

Answer 1

• state of being unarousable & unresponsive to external stimuli or internal needs

Question 2

how are the causes of coma categorized (2)

Answer 2

1. where they originate

2. structural or metabolic (Nonstructural)

Question 3

what are the categories of coma based off where they originate

Answer 3

1. within the cranium = intracranial

2. outside the cranium = extracranial

Question 4

what are examples of structural causes of coma (4)

Answer 4

• hemorrhages
• hematoma
• infarction
• tumours

all lead to increased ICP & brain herniation

Question 5

what are some examples of metbolic causes of coma (3)

Answer 5

• drugs
• hypercalcemia
• uremia

Question 6

what do nonstructural comas cause

Answer 6

• a confusional state, but if severe, coma

- most are reversible

Question 7

what signs are seen with a nonstructural coma

Answer 7

• often pupil size is normal, since ICP Is not elevated

- may effect medullary function

Question 8

is coma irreversible or not?

Answer 8

• can be reservsible or irreversible depending on the cause & severity of brain failure

Question 9

describe how supratentorial lesions progress? what does it influence?

Answer 9

cranial-to-caudal fashion

• top (cortex) to base (brainstem)
• indicates the degree of cerebral & brainstem dysfunction

Question 10

what is lock in syndrome

Answer 10

• condition where the pt is aware & capable of thinking, but is paralyzed & unable to communicate

Question 11

what causes lock in syndrome

Answer 11

• incomplete damage to the cerebrum , where brainstem function is preserved

Question 12

what does severe cerebral damage result in

Answer 12

a vegetative state:

• all cognitive abilities are lost
• but sleep-wake cycles and brainstem function remains

Question 13

what occurs when all cortical functions are lost (2)

Answer 13

• the individual assums decorticate or flexor posturing

- cheyne’s stokes respirations

Question 14

what occurs if the lesions progresses to the midbrain & pons (3)

Answer 14

• pupils become fixed (bc the oculomotor nerve is in the midbrain)
• decerebrate or extensor posturing occurs
• oculocephalic reflex is impaired

Question 15

what is the oculocephalic reflex

Answer 15

• aka doll’s eyes reflex
• normally, when you move a pts head to the side quickly, the eyes remain fixated on one position in place (ex. continue looking at a board in the middle of the room)

Question 16

what happens if the oculocephalic reflex is impaired

Answer 16

• when turning the pt’s head quickly to one side, the eyes remain mid position

Question 17

what do medullary lesions result in (3)

Answer 17

• flaccididty
• loss of gag & cough reflex
• apnea

Question 18

what assessment is used to determine the severity of a coma

Answer 18

• the glascow coma scale

Question 19

what is the glascow coma scale based on

Answer 19

• the cranial to caudal progression

Question 20

what 3 areas does the glascow coma scale measure

Answer 20

• eye opening
• motor response
• verbal response

Question 21

what does the glascow coma scale determine

Answer 21

• what parts of the brain are effected

- specifically, if the brain stem functions are involved

Question 22

what does a high glascow coma score mean? low?

Answer 22

• high = little brainstem involvement

- low = medullary reflexes impaired

Question 23

define brain death

Answer 23

• irreversible loss of brain & brainstem function

Question 24

what does “life support” do

Answer 24

• keeps cells of the body alive & functional despite complete failure of the brain

Question 25

what is a key cause of brain death? what causes it? (3)

Answer 25

• severe cerebral ischemia resulting from increased ICP, cardiac or resp arrest, or severe metabolic disturbance

Question 26

when is determination of brain death required

Answer 26

• whenever an artificial ventilator is required for respiration, but cardiac function is preserved

Question 27

what is the 7 criteria for diagnosis of brain death

Answer 27

• no spontaneous movements, seizures, or posturing
• no response to any kind of painful stimuli in the innervated area of nerves
• absence of brainstem reflex
• no spontaneous reaction to a PCO2 of 60 mmHg
• rule out possible contributing factors
• confim that it is due to irreversible brain damage
• verify that findings are unchanged up to 24 h later

Question 28

what might still be intact during brain death

Answer 28

• spinal reflexes

Question 29

what types of brainstem reflexes must you assess for diagnosis of brain death

Answer 29

• pupillary reflex to light
• gag reflex
• oculocephalic reflex

Question 30

what are possible contributing conditions to brain death (4)

Answer 30

• drugs that depress the CNS or block neuromuscle junction
• hypothermia
• hypoglycemia
• electrolyte disturbances