Traumatic Brain Injury Flashcards
Traumatic Brain Injury
Primary and secondary insults
> what they lead to?
Primary insult
Hemorrhage
Damaged parenchyma
Neuroaxonal injury
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Secondary Insult
Ischemia
Edema > Maximal effects at 24-48 hrs
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This leads to increased ICP
Initial Goals for head trauma
Determine extent of injuries
Assess brain function
Broadly localize neurological lesion
> cortical is ‘good’, brainstem is ‘bad’
Patient Assessment for head trauma case
Level of consciousness
Respiratory pattern / Systemic signs
Cranial nerve examination
Head
> Palpate for fractures
> Bleeding / Leakage of CSF – ears, nose, wounds
Pain perception to limbs
Motor function / Postural reactions
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GPE with MINIMAL manipulation of the head/neck
decreased level of mentation comes from one of these places:
- Cerebrum (bilateral & severe)
- Brain stem – ascending reticular activating system (ARAS)
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Deficits in the cranial nerves indicate:
brain stem involvement
Respiratory Pattern for new head trauma patient
Markedly abnormal respiratory patterns mean what?
Respiratory centers are located centrally
Markedly abnormal respiratory patterns
> Suggest brainstem lesion
> Carry a poor prognosis
Systemic Signs of head trauma
Cushing’s Reflex
Hypertension
+
Bradycardia
Cushing’s Reflex - what is it? what does it mean?
CPP=MAP–ICP
> if our ICP goes up very high, then our MAP must rise to maintain cerebral perfusion
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To maintain cerebral perfusion pressure (CPP):
If ICP rises, then MAP must also rise
This increased MAP triggers a baroreceptor mediated BRADYCARDIA
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Cushing’s Reflex = Systemic Hypertension + Bradycardia
> Imminent brain herniation
Pupillary Light Reflex - what it tells us?
Assesses
CNII & CNIII
> Constriction suggests CN III is intact
Note even fine changes
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> CN 3 is at a very important segment of the brainstem
PLR - what does this tell us?
- even a small change in pupil width tells us PLR and thus CN3 is intact
Brainstem Lesion - what will this look like in the eyes? what does this mean for lesion localization and prognosis?
Pupils
Dilated
Central
Unresponsive
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Lack of CNIII input
Midbrain / Pons
Grave prognosis
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Pupils
Asymmetry
Ocular vs brain trauma
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Unilateral rapid changes
ICP
Physiologic Nystagmus - tells us what?
Evaluates
CN III, IV, VI, VIII
Medial Longitudinal Fasciculus
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Global assessment > means we have a breadth of our brainstem that is doing well
Decerebrate Rigidity - tells us what? what does it look like? prognosis?
Cortical injury
Disconnection of the higher centres of the brain &
brainstem
Patients are comatose, lack PLR, dilated or pinpoint pupils
Rigidity - extension of all 4 limbs & tail, opisthotonus
GRAVE prognosis
Decerebellate Rigidity - tells us what? what does it look like? prognosis?
Cerebellar injury
Patients are ALERT & aware
Neck & forelimbs are in extension
Hindlimbs are normal (or hyperflexed)
FAVOURABLE prognosis
Modified Glasgow Coma Score - what does it assess? what is the scale? what is its use?
- Motor activity, brainstem reflexes, level of consciousness
- scale goes from 6 (best) to 1 (worst) for each category, then add them up
- It is a good prognostic indicator; higher scores mean better prognosis
Imaging for head trauma - when to do skull ultrasound
puppies, tiny dogs, open skull fractures
Imaging for head trauma - use of CT and MRI?
CT preferred:
> Acute hemorrhage & bone are better visualized
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MRI
> ID more subtle lesions
> Findings ass’d with prognosis
skull fractures - incidence with brain trauma? associated with what conditions?
- 46-72% incidence
- associated with Development of seizures, post traumatic epilepsy
> Worse outcome at 3, 6, 12 months
Factors Affecting ICP
Intracranial mass lesion – hemorrhage, depressed skull fracture
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Cerebral edema (aggravated by ischemia / poor brain perfusion)
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Vasodilation:
Venous return
> Head position
> Intrathoracic / intraabdominal pressure
Cerebral vasodilation - increased PaCO2 ; decreased PaO2
Fluid overload
Hyperthermia
Venous sinus thombosis or other obstruction
Seizures
Emergency Management for head trauma
- Airway/Breathing/Circulation
- IV access
- O2 Supplementation - Stabilize the patient
- ie. pneumothorax, fatal arrhythmias, etc
Treatment for head trauma
“make all vitals perfect”
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- Maintain normal BP
> MAP 90-100 +mmHg
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- Resuscitate to NORMOVOLEMIA
> Maximize O2 delivery
> Minimize fluid overload
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- O2 Supplementation
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- Fluid Resuscitation
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- Pain Management
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etc…
Fluid Resuscitation for brain trauma cases - what are our principles? primary considerations??
Low volume resuscitation
Crystalloids
Hypertonic Saline
Colloids
Blood
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Risks of HYPOTENSION/ HYPOVOLEMIA far outweigh risks of overhydration
indication for crystalloids for fluid resuscitation in head trauma case? rate?
what if hypotension persists?
Indication
Mild hypotension
MAP 60-80 mmHg
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Rate
Dog – 40 ml/kg (up to max 70 ml/kg)
Cat – 20 ml/kg (up to max 40 ml/kg)
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If hypotension persists
Add hypertonic saline / colloid
O2 Supplementation for head trauma patient
- goal?
- what to avoid? why?
- hypoxemic vs hyperoxemic states and outcomes
Goal – normoxia
> Pulse oximeter 95-98%
> PaO2 3 80mmHg – 105 mmHg
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Avoid nasal prongs / cannulas > we dont want sneezing
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Hypoxemia – leads to vasodilation, increased ICP & decreased cerebral blood flow
Hyperoxemia – also associated with worse outcomes related to ROS!
Pain Management for brain trauma case
- what to use and how?
Use opioids - TITRATE
- Fentanyl > Short acting, easy to adjust
- Methadone
- Hydromorphone
> TITRATE – avoid vomiting!!!!!!!!!!!!!!!!
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- Opt for NSAIDs once animal stable
what signs are we looking for in a head trauma case to start treatment to avoid brain herniation?
- decreased Level of consciousness
- Cushing’s reflex
Bradycardia
Hypertension - Loss of PLR / Rapid change in pupil size / Loss of physiologic nystagmus
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≥ 2 signs ….. TREAT!!!
Elevated ICP - how to treat?
Hyperosmolar therapy
Mannitol
Hypertonic saline
what is mannitol? what does it do?
contraindications?
Osmotic diuretic, useful for treating elevated ICP
Decreases blood viscosity
Free-radical scavenger
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Contraindications:
Hypovolemia, CHF
Ongoing intracranial hemorrh (empirical)
IV continuous infusion not recommended
Hypertonic Saline - use for treatment of elevated ICP? caution?
Hyperosmolar solution
‘Draws’ out brain edema
Also: Improves CBF & O2 delivery
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Caution – maintain Na+ < 160 mmol/L
Hyperosmolar Therapy for increased ICP - treatment plan overall, monitoring?
mannitol or Hypertonic Saline
Try one, if little effect, try the other!
May need to repeat
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Monitoring q8 hr or more often
Hydration
Electrolytes
Corticosteroids for increased ICP? what do they do?
Not Recommended
No beneficial effect to reduce cerebral edema
May perpetuate:
> Neuronal damage if ischemia present
> Hyperglycemia
Standard dosing of prednisone & dexamethasone particularly unlikely to benefit
CO2 Management for brain trauma patient? values?
- Hyperventilation
> decreased PaCO2 > Cerebral Vasoconstriction > Short-term only
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PaCO2 – 30 mmHg (No less)
ETCO2 – 35 mmHgw
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Topical laryngeal lidocaine spray
Pretreat w IV lidocaine 0.75mg/kg IV prior to intubation
Induce with propofol
Anesthetic Considerations for brain trauma - which do we prefer? why?
Propofol preferred ; Barbiturate alternative
- Reduces cerebral metabolic rate for O2
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Sedation
Benzodiazepines
Alpha 2 agonists -
> Ultra low doses only
> Dexmedetomidine 1-2 mcg/kg/hr
positioning for brain trauma patient
Improve Venous Drainage
Head elevated 30°
Avoid occlusion of the jugular veins
Maintain normal intrathoracic/abdominal pressures
Prevent coughing/sneezing/vomiting
how to Prevent Hyperthermia in the brain trauma patient - how should we regulate temp?
Maintain temp at low end of normal
Allow patient to rewarm passively if the patient is hypothermic on presentation
Avoid shivering > shivering using oxygen
> Temp > 36.5°C (98°F)
issues with hyperglycemia and hypoglycemia in the brain trauma patient
hyperglycemia:
Associated with increased cerebral lactate / acidosis & cell death
Worsening neurological outcome
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hypoglycemia:
Worse cerebral metabolic effects
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Normoglycemia is the goal
Seizure Management for the head trauma patient
- incidence?
- treatment
- management
Seizure incidence
~ 14+% within 24 hours of injury, or within 1 week of injury
Increased incidence with skull fractures & herniation
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Treatment
Diazepam
Levetiracetam
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Management
Levetiracetam PO TID
Diazepam infusion
Phenobarbitol
antiemetics for head trauma patient? what about hemorrhage control?
- yes we can try to do both
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Antiemetic
Maropitant
Metoclopramide
Dimenhydrinate
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Tranexamic Acid
Anti-fibrinolytic (maintain clot)
Control hemorrhage
General Management for head trauma patient
Early enteral feed
Eye care / oral care
Avoid bladder distension —- increase ICP
> Continuous drainage
Nursing care (turning patient, physio)
Recovery for head trauma patient
Time!
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Expectations:
Ataxia
Circling
Signs of cerebellar disease
** Markers of improvement in previously recumbent patient **
> most of the time recover well if they survive first 24 hours
Critical Periods for head trauma patient
1st 24 hours for survival
1st 72 hours for change in neuro status > if they make it this far, in good shape!
Thereafter recovery period
Prognosis for brain trauma patient
Non-survival (mortality ~15%) predicted by:
- Modified Glasgow Coma Score
- ≦ 8 associated with ~ 50% non-survival
- Concurrent injuries with evidence of decreased perfusion / oxygenation (ie. Increased lactate, decreased pH, SpO2)
- Need for endotracheal intubation or HTS administration
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Poor outcome ass’d with:
Brain herniation
Skull fractures
Increased size of intra-parenchymal lesions
Sequelae to brain trauma
Impossible to predict at initial exam
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Thalamocortical injury
Personality changes
Visual deficits
Circling
Weakness in 1+ limb
Late onset epilepsy - seizures within 1 year of injury
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Generally excellent prognosis
brain trauma summary
- things to focus on for assessment
- keep in mind, what to regulate, what to watch for
- overall prognosis
Important points
Good neurological assessment
Appropriate lesion localization
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Rapidity of changing neuro status
Regulation of blood pressure, O2, CO2
Recognition of signs of imminent brain herniation
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Excellent prognosis in many patients
