Traumatic brain injury Flashcards
Define traumatic brain injury
An alteration in brain function or other evidence of brain pathology caused by an external force
What are the common mechanisms that can cause a TBI?
MVC/MCC/ Car vs ped
Fall
Industrial accident
Assault
Sports injury
In regards to TBI, what is a coup?
Any blow to the skull
In regards to TBI, what is countrecoup?
Blow to the head where the impact transfers through the skull to the opposite side of the head causing damage to the side opposite the initial point of injury
A patient with a mild TBI can present with
Headache
Confusion
Dizziness
Memory impairment
Blurred vision
Behavioral changes
A patient with a moderate TBI can present with
Repeated nausea or vomiting
Slurred speech
Weakness in arms or legs
Problems with thinking or learning
A concussion is formally referred to as:
A diffuse axonal injury
Describe the damage that is associated with a diffuse axonal injury
Centripetally applied forces can damage nerve fibers by shearing the fiber or disrupting the myelin sheath
Can result in varying degrees of coma or death
Where is an epidural hematoma located?
Between the skull and the dura
Where is a subdural hematoma located?
Between the dura and the arachnoid mater
Where is a subarachnoid hemorrhage located?
Beneath the arachnoid mater within the subarachnoid space
Describe the Monroe-kelli doctrine
There is a limited amount of space in the brain
To compensate for swelling or a mass, the body will remove CSF and venous volume to try to accommodate for the growth.
This is limited and eventually pressure will rise in the intracranial space
What is a normal ICP for a supine patient?
10-15 mmHg
When does brain death occur due to increased ICP?
When ICP=MAP
What ICP is the ceiling for most ICU patients?
20 mmHg
What happens if ICP is 15-20 mmHg?
Capillary beds are compressed altering microcirculation
What happens if ICP is between 30-35 mmHg?
Provokes edema
What happens if ICP is between 40-50 mmHg?
Does not support perfusion
How do we calculate cerebral perfusion pressure?
CPP = MAP-ICP
What does a cerebral perfusion pressure of less than or equal to 50 cause?
Frank cerebral ischemia
What have recent studies shown regarding Cerebral perfusion pressure?
Poor outcomes for patient with CPP of less than or equal to 60
What is a normal Cerebral Perfusion Pressure? CPP
95-80 mmHg
What are the categories of responses for the glasgow coma scale?
Eye opening response
Verbal response
Motor response
What are the eye opening response levels
Spontaneously
To speech
To pain
None
What are the verbal response levels?
Oriented to time, person, place
Confused
Inappropriate words
Incomprehensible sounds
No response
What are the motor response levels
Obeys command
Moves to localized pain
Flex to withdraw from pain
Abnormal flexion
Abnormal extension
No response
When does the glasgow coma scale indicate intubation?
Intubation is indicated for GCS < 9
Describe decorticate posturing
Patient pulls arms up to chest with palms facing down
Describe decerebrate posturing
Patient puts hands by sides with palms rotated inward and outward
A patient you are assessing has pupils that are large and unresponsive to light. The patient is not on drugs, what is this indicative of?
Increased ICP leading to paralysis of the optic nerve
What is the fancy term for a blown pupil?
Mydriasis
Impending or ongoing cerebral herniation can be indicated by what?
Posturing
Pupillary asymmetry
Mydriasis
Cushing triad
What is cushing triad?
Hypertension
Bradycardia
Irregular respiration
When referring to a TBI, what is meant by the term midline shift?
The compression or movement of the ventricles on one side of the brain in response to swelling
What can happen if ICP remains unchecked?
Brain can be pushed out of its normal position
Describe secondary brain injury
A cascade of subtle changes in the brain and nervous system following a primary injury
What changes can cause secondary injury in the brain?
Cerebral edema
Inflammation
Electrolyte imbalances
Hypoxemia
Poor BP control
Poor glucose management
Poor vent management
Seizures
What is the cause of cerebral edema in most adults?
Vasogenic edema
What causes cerebral edema?
Increased permeability of the cerebral vasculature/ breakdown of the blood brain barrier
What are management options for cerebral herniation
Hyperosmolar IV solutions
External ventricular drains
Evacuation of blood clot
Craniectomy
How do hyperosmolar solutions manage cerebral herniation?
Increased salinity of blood pulls fluid out of tissue reducing swelling
Generally 3% hypertonic saline
Describe how extraventricular drains can manage cerebral herniation
A catheter is placed in cerebral ventricle allowing for pressure monitoring and fluid drainage to control ICP
What is respiratory’s role in traumatic brain injuries?
Prevent second degree brain injury
Gentle intubations
Management of ventilation
Management of oxygenation
What effects can hyperventilation have on TBI patients?
PaCO2 < 25 mmHg can rapidly decrease ICP
Can also reduce blood flow to the brain
Why is a gentle intubation important with TBI patients?
Intubation can stimulate supraglottic larynx which somehow can spike ICP
What should providers be aware of when choosing PEEP settings for patients with TBIs?
Increased intrathoracic pressure inhibits venous return to the heart which can increase ICP
Problematic because PEEP is what we use to promote oxygenation
What are the guidelines regarding hyperventilating TBI patients?
Prophylactic hyperventilation should be avoided
PaCO2 of 25-30 mmHg can sometimes be used as a temporary measure to resolve and ICP crisis
Hyperventilation induced vasoconstriction can cause secondary ischemia and worsen patient outcomes
When can hyperventilation of TBI patients be especially harmful?
In the acute phase, 24-48 hours after injury
If a patient with a TBI experience mental status changes, what needs to be performed?
A CT scan
