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Paramedic Revision > Traumatic Brain Injuries > Flashcards

Traumatic Brain Injuries Flashcards

1
Q

What is a traumatic brain injury (TBI)?

A

a brain injury caused by an external injury to the head

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2
Q

what is a primary brain injury?

A

injury to the brain tissues as a direct result of neurotrauma

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3
Q

what is a secondary brain injury?

A

Brain damage occurring post injury as a result of extracranial causes, such as hypoxia, hypotension or hypoglycaemia, or intracranial causes, such as haemorrhage, swelling or infection

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4
Q

what is an acquired brain injury (ABI)?

A

any kind of brain damage that occurs after both. Most ABI’s are associated with drug and/or alcohol misuse, infections, strokes, and other diseases

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5
Q

what determines the severity of a primary brain injury?

A

the extent of neuronal and vascular damage

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6
Q

what are the three classifications given to the mechanism of a TBI?

A

impact loading, impulsive loading, and static loading

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7
Q

what is impact loading?

A

this describes a TBI which occurs as a result of contact and inertial forces. It is defined as the head colliding with a solid object at a tangible speed. E.g. in a motor bike accident if the patient is thrown from the bike and their head collides with a tree

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8
Q

what is impulsive loading?

A

this describes when the head is in motion and inertial forces lead to acceleration-induced TBI. For example in a car accident when someone is rear ended. Their head will jerk forward despite not necessarily coming into contact with an object. This causes the brain to move within the skull

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9
Q

what is static loading?

A

this describes a TBI that has occurred when the head becomes trapped between a rigid object and a slow moving object which gradually squeezes the head and skull. It generally results in multiple fractures and results in deformity of the skull and brain

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10
Q

what does a closed skull fracture describe?

A

when the skull is fractured but there is not interaction with the outside environment, i.e. the skin is not broken

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11
Q

what is an open skull fracture?

A

when the skull is fractured and the skin is broken allowing communication with outside environment

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12
Q

what is a simple skull fracture?

A

only one bone fragment

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13
Q

what is a compound skull fracture?

A

multiple bone fragments

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14
Q

what does a linear skull fracture describe?

A

a line in the skull that passes through it’s full thickness, generally a result of a significant blow

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15
Q

what does a depressed fracture describe?

A

occurs when there is significant bone fragmentation which causes an actual depression in the skull surface. Generally a result of a significant mechanism of injury. Bone fragments can become lodged in the underlying brain tissue.

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16
Q

What is a base of skull fracture?

A

fractures involving the base of the skull and cribriform plate

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17
Q

what structures are most commonly affected by a base of skull fracture?

A

the petrous portion of the temporal bone, external auditory canal, and the tympanic membrane

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18
Q

what are some tell tale signs of a base of skull fracture?

A

clear fluid (cerebrospinal fluid) leakage from the ears, periorbital ecchymosis (raccoon eyes), and a ‘battle sign’ which is a bruise that develops over the mastoid process (behind ear) 12-24 hours after the insult

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19
Q

why can CSF leakage occur in a base of skull fracture?

A

because base of skull fractures are often associated with tearing of the dura mater

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20
Q

where in the skull does cerebrospinal fluid flow?

A

in the subarachnoid space

21
Q

from superficial to deep, what are the layers of the head, skull and meninges?

A

skin, periosteum, skull, dura mater, subdural space, arachnoid mater, subarachnoid space, pia mater, brain

22
Q

what is a concussion?

A

a transient reduction in cerebral functioning without structural defect, often caused by an acceleration injury or blunt force trauma. It is thought that the Reticular Activating System is impacted

23
Q

what are some signs of concussion?

A
  • light headedness
  • vertigo
  • nausea
  • vomiting
  • tinnitus
  • photophobia
  • fatigue
  • cognitive disfunction
24
Q

what is cerebral contusion?

A

bruising of the brain tissue resulting in an alteration of neurological function that includes conscious level

25
Q

what are the most common locations for cerebral contusions to occur?

A

the frontal and temporal lobes

26
Q

what is a coup contusion?

A

a contusion/bruise that occurs at the site of impact

27
Q

what is a contrecoup contusion?

A

a contusion/bruise that occurs opposite the site of impact

28
Q

review this snapshot of differnt intracranial haemorrhages

A
29
Q

how long after the primary brain injury do the pathphysiological process of a secondary brain injury begin to develop?

A

2-24 hours

30
Q

what are some identifyable symptoms in the development or exacerbation of a secondary brain injury?

A
  • hypotension (systolic BP <90mmHg)
  • hypoxia (SpO2 <90 or PaO2 <50mmHg)
  • hypoglycaemia
  • hyperprexia (body temp goes above 41.5C due to changes in the hypothalamus)
  • hypocapnia (PaCO2 <30mmHg)
31
Q

what is the predominant mechanism of secondary brain injuries?

A

impaired cerebral oxygenation as a result of reduced cerebral blood flow

32
Q

review this clinical snapshot of secondary brain injuries

A
33
Q

what are some causes (list 2-3) of secondary brain injury associated with increased morbidity and mortality?

A
  • hypoxia
  • hypotension
  • hypo/hypercapnia
  • hyperthermia
  • hypo/hyperglycaemia
  • hyperosmolarity
  • hypo/hypernatraemia
  • infection
  • seizure
  • delayed haemotoma
  • subarachnoid haemorrhage
  • vasospasm
  • hydrocephalus
34
Q

regarding the inflammatory process, what is an important consideration when treating someone with a suspected TBI or increased ICP?

A

the inflammatory process can increase membrane permeability, as a result the blood brain barrier may be more susceptible to crossing. It is important to consider this as drugs that usually don’t cross this barrier may have an undesired affect

35
Q

explain the principle of the monroe-kellie doctrine

A

the monroe-kellie doctrine states that as the skull is essentiall a ‘closed vault’ pressure and volume are inversely related. There are three subtances that makeup the inside of the skull, brain tissue (around 1300mL), blood (100-150mL), and cerebrospinal fluid (100-150mL). Essentially, if there is a rise in one of these three things ICP will rise and the volume of the other components will decrease. If a compensatory reduction in volume does not occur, ICP will rise further

36
Q

what percentage of your bodies total oxygen requirements does your brain use?

A

20%

37
Q

what is cerebral perfusion pressure and how is it calculated?

A

The amount of pressure needed to maintain bloodflow to the brain

A calculated measure of blood flow to the brain. CPP is determined by subtracting intracranial pressure from mean arterial blood pressure

38
Q

How is MAP calculated and what does it represent?

A

MAP = 1/3 pulse pressure + diastolic BP
or MAP = (2xdiastolic + systolic BP) / 3

MAP represents the average pressure in a persons arteries during one cardiac cycle

39
Q

What happens if ICP is increased and MAP is decreased?

A

CPP is reliant on a balance of MAP (systemic BP) and ICP. If MAP is ↓ (due to ↓BP) and ICP is ↑, then autoregulatory mechanisms will try to ↑ BP and HR in order to improve CO

40
Q

autoregulatory machanisms responsible for maintaining CPP are sensitive, between what ranges do they work effectively?

A

CPP between 50mmHg and 150mmHg

41
Q

what is cushings reflex?

A

this occurs when a space-occupying mass (e.g haemorrhage, haemotoma) increase intracranial pressure (ICP). This rapid rise in ICP causes brain tissue to become displaced and move towards the foramen magnum. Cushings reflex is a result of this and is characterised by hypertension, bradycardia, and irregular respirations

42
Q

what are the major regulatory machanisms in maintaining adequate cerebral blood flow?

A

PaCO2, blood pressure, and blood pH

43
Q

how do PaCO2, blood pressure and blood pH

A

alterations in these things will cause cerebral vasoconstriction and/or vasodilation

44
Q

does hypotension and/or hypoventilation result in vasoconstriction or vasodilation?

A

hypotension and/or hypoventilation will result in an increase in PaCO2 and therefore a decrease in pH (acidosis). This will cause vasodilation in an attempt to increase cerebral blood flow and oxygen delivery

45
Q

does hypertension, hyperventilation, and/or an increased pH (alkalosis) result in vasodilation or vasocontriction?

A

hypertension and/or hyperventilation will result in a decrease in PaCO2 and therefore an increase in pH (alkalosis). This will cause vasodilation in an attempt to decrease cerebral blood flow

46
Q

what is the glasgow coma scale?

A

a tool used to assess and calculate a persons level of conciousness

47
Q

explain the scoring of the glasgow coma scale

A
48
Q

what are the key considerations in TBI management?

A

airway management - intubations, consider risk of C-spine injury

blood pressure management - important to manage adequate CPP, consider rising ICP and fluid overload

management of intracranial hypertension - positioning, anti-seizure and anti-emetic medication, reduce anxiety-related sympathetic innervation

49
Q
A

Paramedic Revision (22 decks)

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