Week 8 - Coma & Brain Death Flashcards

1
Q

define coma

A
  • state of being unarousable & unresponsive to external stimuli or internal needs
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2
Q

how are the causes of coma categorized (2)

A
  1. where they originate

2. structural or metabolic (Nonstructural)

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3
Q

what are the categories of coma based off where they originate

A
  1. within the cranium = intracranial

2. outside the cranium = extracranial

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4
Q

what are examples of structural causes of coma (4)

A
  • hemorrhages
  • hematoma
  • infarction
  • tumours

all lead to increased ICP & brain herniation

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5
Q

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

A
  • drugs
  • hypercalcemia
  • uremia
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6
Q

what do nonstructural comas cause

A
  • a confusional state, but if severe, coma

- most are reversible

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7
Q

what signs are seen with a nonstructural coma

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

- may effect medullary function

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8
Q

is coma irreversible or not?

A
  • can be reservsible or irreversible depending on the cause & severity of brain failure
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9
Q

describe how supratentorial lesions progress? what does it influence?

A

cranial-to-caudal fashion

  • top (cortex) to base (brainstem)
  • indicates the degree of cerebral & brainstem dysfunction
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10
Q

what is lock in syndrome

A
  • condition where the pt is aware & capable of thinking, but is paralyzed & unable to communicate
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11
Q

what causes lock in syndrome

A
  • incomplete damage to the cerebrum , where brainstem function is preserved
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12
Q

what does severe cerebral damage result in

A

a vegetative state:

  • all cognitive abilities are lost
  • but sleep-wake cycles and brainstem function remains
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13
Q

what occurs when all cortical functions are lost (2)

A
  • the individual assums decorticate or flexor posturing

- cheyne’s stokes respirations

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14
Q

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

A
  • pupils become fixed (bc the oculomotor nerve is in the midbrain)
  • decerebrate or extensor posturing occurs
  • oculocephalic reflex is impaired
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15
Q

what is the oculocephalic reflex

A
  • 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)
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16
Q

what happens if the oculocephalic reflex is impaired

A
  • when turning the pt’s head quickly to one side, the eyes remain mid position
17
Q

what do medullary lesions result in (3)

A
  • flaccididty
  • loss of gag & cough reflex
  • apnea
18
Q

what assessment is used to determine the severity of a coma

A
  • the glascow coma scale
19
Q

what is the glascow coma scale based on

A
  • the cranial to caudal progression
20
Q

what 3 areas does the glascow coma scale measure

A
  • eye opening
  • motor response
  • verbal response
21
Q

what does the glascow coma scale determine

A
  • what parts of the brain are effected

- specifically, if the brain stem functions are involved

22
Q

what does a high glascow coma score mean? low?

A
  • high = little brainstem involvement

- low = medullary reflexes impaired

23
Q

define brain death

A
  • irreversible loss of brain & brainstem function
24
Q

what does “life support” do

A
  • keeps cells of the body alive & functional despite complete failure of the brain
25
Q

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

A
  • severe cerebral ischemia resulting from increased ICP, cardiac or resp arrest, or severe metabolic disturbance
26
Q

when is determination of brain death required

A
  • whenever an artificial ventilator is required for respiration, but cardiac function is preserved
27
Q

what is the 7 criteria for diagnosis of brain death

A
  • 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
28
Q

what might still be intact during brain death

A
  • spinal reflexes
29
Q

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

A
  • pupillary reflex to light
  • gag reflex
  • oculocephalic reflex
30
Q

what are possible contributing conditions to brain death (4)

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