Moderate-to-severe traumatic brain injury
Head trauma associated with a depressed GCS.
- Moderate: accounts for approximately 10% of traumatic brain injury.
- Severe: accounts for approximately 10% of traumatic brain injury.
- Traumatic Brain Injury (TBI): Impairment in brain function from a mechanical force
- Bruises to brain parenchyma
- Diffuse axonal injury
- Direct cellular damage
- Tearing and shearing of tissues
Brain swelling causes increased ICP which compresses the tissue causing ischemia with direct compression of the vasculature causing brain tissue herniation and brain death
- Leads to expansion of the original injury (predominantly metabolic insult)
- Calcium and sodium shifts
- Mitochondrial damage
- Production of free radicals
- Ultimately leads to damage to axonal integrity and axonal transport
- Enzyme activity leads to apoptosis
- Microscopic structural injury is often unidentifiable on CT or MRI
Cerebral Blood Flow and Autoregulation
- HTN, Hypocarbia, alkalosis
- No good way to measure cerebral blood flow
- Use CPP as surrogate
- CPP is amount of pressure needed to perfuse the brain
- When ICP elevates, CPP decreases
- Normal ICP
- 15 in adults
- <10 to 15 in children
- 1.5 to 6.0 in infants
- Use CPP as surrogate
- Autoregulation allows the body to control the cerebral blood flow
- Autoregulatory mechanism is damaged in most TBI patients
History and physical examination often limited.
- Calculate GCS
- Pupils: may identify herniation syndromes
- Focus on symmetry as hemiparesis may suggest herniation syndrome
- Elicit movement with noxious stimuli in non-cooperative patients
- Note voluntary or purposeful movement (crossing the midline, approaching the stimulus, pushing the examiner's hand away)
- Cranial Nerves
- Assessable cranial nerves: pupils (III), corneal (V, VII), gag (IX, X), VOR (VII, VI)
- Plantar extensor response: non-specific, delineates disruption along corticospinal tract (cortex to LMN)
More common in children than adults
- Triad of:
- Traumatic brain injury
- Orbital trauma
- Maxillofacial trauma
- Skull fracture
- Pediatric head trauma
- Penetrating neck trauma
- Blunt neck trauma
- Cervical injury
- Neurogenic shock
- Spinal cord injury
- Emergent, non-contrast head (cranial/brain) computed tomography
- Face and/or orbit CT
- C-spine CT
- Blood glucose (hypoglycemia increases risk of secondary injury and also lowers seizure threshold)
- Miscellaneous labs
- Beta-2 transferrin for CSF leak, needs 0.5 cc of fluid
|6: Obeys commands|
|5: Oriented||5: Localizes to pain|
|4: Spontaneously opens||4: Confused speech||4: Withdraws from pain (normal flexion)|
|3: Opens to command||3:Inappropriate words||3: Decorticate posturing (abnormal flexion)|
|2: Opens to pain||2: Incomprehensible sounds||2: Decerebrate posturing (extension)|
|1: Does not open||1: No response||1: No response|
- 14-15: Mild
- 9-13: Moderate
- 3-8: Severe
- Core temperature, Foley with bladder probe
- ICP monitoring
- Jugular venous oxygen saturation (SjvO2) by retrograde catherization of right IVJ associated with improved outcomes
- Normal range 55-70%
- Sustained desaturation < 50% requires aggressive treatment
- Transcranial doppler around thinner walls of skull (insonation windows)
- Temporal region above zygomatic arch, through eyes, below jaw, behind occiput
- Sensitivity for brain death is ~75%, specificity 98%
Main goals in management
- Prevent intracranial hypertension
- Prevent secondary brain insults
- Maintain Cerebral Perfusion Pressure (CPP) > 70 mmHg
- Optimize cerebral oxygenation and blood flow
- Monitor for increased ICP
- Monitor for herniation
- Maintain PaO2 > 60 mmHg
- Prevent hyperthermia
- Prevent hypotension
- Correct coagulopathy (FFP, vitamin K, PCC, desmopressin)
- Tranexemic acid
- Indication: GCS ≤ 12 OR any intracranial bleeding on CT scan AND ≤ 3 hours since time of injury
- Loading dose 1 g over 10 min; followed by maintenance dose of 1 g over 8 hrs
- NNT = 76.9
- Minimize secondary injury
- Identify treatable mass lesions
- Identify and manage other life-threatening injuries
- Stabilize and rapidly transport
- Manage airway and blood pressure
- Prehospital intubation controversial
- Concern is that it leads to post-intubation hyperventilation
- Normal saline for hypotension
- Mannitol not needed prehospital if transport times are short
- Prevent secondary insult and slow expansion of the injury
- Intubate if GCS<8
- Short-acting induction agents with little effect on BP or ICP preferred
- Long-acting neuromuscular blockers make it difficult to detect seizure
- Avoid hypoxia (SpO2 <90%, PaO2 <60mmHg)
- Early endotracheal intubation is indicated.
- Pre-oxygenation: Hyperoxia in TBI can be harmful, however it can be assumed that resumption of targeting normoxemia immediately after securing airway control outweighs the potential harm of hypoxia during intubation (which can often be challenging in these settings due to maxillofacial trauma and maintenance of cervical spine precautions).
- Pre-treatment: No clear benefit to use of lidocaine to blunt reflex sympathetic response to laryngoscopy.
- Induction: Selection of induction agent remains controversial:
- Etomidate is well-studied with a stable hemodynamic profile
- Ketamine which has shown promise in some trials due to its hemodynamic profile (commonly increased MAP and subsequently CPP) without previously-cited deleterious effects on ICP and may be the agent of choice for patients with hemodynamic compromise .
- Paralysis: No apparent benefit to the addition of a defasciculating dose of non-depolarizing neuromuscular blocking agent (to prevent transient elevation of intracranial pressure associated with widespread muscle fasciculation).
- Avoid hyperventilation as hypocapnia induces cerebral vasoconstriction, target low-normal PCO2 of 35mmHg.
- Avoid hypotension (SBP <90mmHg)
- Fluid resuscitation with isotonic saline, and vasopressors if refractory.
- Albumin should be avoided.
- No apparent benefit to the initial administration of hypertonic saline .
Management of Impending Herniation
Hyperosmolar therapy is indicated for patients with objective elevations of intracranial pressure or signs of impending or ongoing herniation.
- Both hypertonic saline and mannitol are effective at reducing intracranial pressure.
- Meta-analyses of limited and variable data suggest benefit towards hypertonic saline.
Increased ICP Treatment
Head of Bed elevation
- 30 degrees or reverse Trendelenburg will lower ICP
- Keep head and neck in neutral position, improving cerebral venous drainage
- Avoid compressing IVJ or EVJ with tight C-collars or fixation of ETT
Maintain cerebral perfusion
- CPP = MAP-ICP
- If MAP <80, then CPP<60
- Ultimately no Class 1 evidence for optimal CPP
- Transfuse PRBCs with goal Hb > 10 mg/dL in severe TBI
- Provide fluids and vasopressors if needed for goal cerebral perfusion pressure (CPP) of 70-80 mmHg
- Mortality increases 20% for each 10 mmHg loss of CPP
- Avoid dips in CPP < 70 mmHg, which is associated with cerebral ischemia and glutamate increase
- Phenylephrine increases CPP without increasing ICP in animal models
- May be beneficial when patient is tachycardic (reflex bradycardia), but avoid phenylephrine if patient is already bradycardic (Cushing's reflex)
- Phenylephrine may be associated with less cell injury as compared to norepinephrine in TBI
- IV fluids
- Maintain euvolemia, initially resuscitate with Normal Saline
- Then consider hypertonic saline and/or mannitol
- Do not use free water, low osmolal, dextrose-alone solutions, and colloids
- Do not use Ringer's lactate as it is slightly hypotonic
- Prefer NS over D5-NS if possible, but D5-NS may be necessary to avoid hypoglycemia, especially in younger pediatric patients
- Correction of severe hypernatremia > 160 mmol/L (hypothalamic-pituitary injury, diabetes insipidus) should be gradual to not worsen cerebral edema
Therapies include either mannitol or hypertonic saline. In choosing the appropriate agent, coordinate with neurosurgery and take into account the patient's blood pressure. Mannitol may cause hypotension due to the osmotic diuresis.
- If SBP > 90 mmHg
- Bolus 20% at 0.25-1 gm/kg as rapid infusion over 15-20 min
- Target Osm 300-320 mOsm/kg
- Reduces ICP within 30min, duration of action of 6-8hr
- Monitor I/O to maintain euvolemia during expected diuresis and use normal saline to volume replace
- Do not use continuous infusions, as mannitol crosses the BBB after prolonged administration and contributes to cerebral edema
- Consider hypertonic saline for further boluses
- Hypertonic saline has higher osmotic gradient and is less permeable across BBB than mannitol
- Hypertonic saline may be more effective than mannitol, current standard of care
- Obtain baseline serum osmolarity and sodium
- Most studies used 250 mL bolus of 7.5% saline with dextran
- Initial 250 cc bolus of 3% will reduce ICP and can be delivered through a peripheral line
- Target sodium 145-155 mmol/dL
Prevent Cerebral Vasoconstriction
- Hyperventilation does not improve mortality, used only as temporizing measure
- Should only be used if reduction in ICP necessary without any other means or ICP elevation refractory to all other treatments:
- CSF drainage
- Hypertonic saline, osmotic diuretics
- Maintain PaCO2 35-40 mmHg for only up to 30 minutes, no longer if it can be avoided
- Hyperventilation to PaCO2 < 30 mmHg not indicated, and decreases cerebral blood flow to ischemic levels
- Treat immediately with benzodiazepines and antiepileptic drugs (AEDs)
- Consider propofol for post-intubation sedation
- Seizure prophylaxis reduces seizures but does not improve long-term outcomes
- AEDs prevent early seizures (which occur between 24 hrs - 7 days), with NNT = 10 by Cochrane Review
- Risk factors for post-traumatic seizures:
- Treat any clinically apparent and EEG confirmed seizures
- Consider prophylaxis in patients with any risk factors as above
- Phenytoin or fosphenytoin first line agent by BTF guidelines
- Load 20 PE/kg IV, then 100 PE IV q8hrs for 7 days
- Measure serum levels to titrate to therapeutic levels
- Levetiracetam may be used as alternative
- 20 mg/kg load IV, followed by 1000 mg IV q12h for 7 days
- Levetiracetam may have less frequent and severe adverse drug side effects events as compared to phenytoin
- In many EDs, levetiracetam is current first line therapy
Goal cerebral perfusion pressure (CPP) ~70mmHg
- If need for RSI, consider pretreatment with lidocaine and/or fentanyl
- May contribute to peri-intubation hypotension
- Also ensure adequate sedation (prevent gag reflex)
- Etomidate may cause adrenal insufficiency especially in head injured patients, so consider hydrocortisone if refractory hypotension post-intubation
Decrease metabolic rate
- Provide adequate sedation and analgesia
- Avoid HYPERthermia and treat fever aggressively
Other Critical Care Measures
- DVT prophylaxis with SCDs, no anticoagulation
- Stress ulcer prophylaxis with H2 blocker/PPI and sucralfate to avoid Cushing's ulcers
- Good glycemic control, but tight maintenance not supported
- Steroids, methylprednisolone contraindicated in severe TBI (risk of death increased in CRASH 2004 trial)
- Routine paralysis not indicated
- Increased risk of pneumonia and ICU length of stay
- However, may be used for refractory ICP elevation
- For ICP refractory to maximal medical and surgical therapy
- Only for hemodynamically stable patients
- Induce with the following:
- Pentobarbital 10 mg/kg over 30 min
- Then 5 mg/kg/hr for 3 hrs
- Followed by 1 mg/kg/hr
Guidelines for Neurosurgical Intervention
- Intracranial pressure monitoring is indicated for salvageable patients with severe TBI and abnormal CT (hematoma, contusion, swelling, herniation, compressed basal cisterns)
- Surgical intervention/evacuation is indicated for:
- Epidural Hematoma: volume >30mL or any with GCS <8 or anisocoria
- Subdural Hematoma: >10mm width with >5mm of midline shift, any with GCS <8 or decline >2
- Posterior Fossa Hemorrhage: if mass effect (distortion of 4th ventricle, obstructive hydrocephalus)
- Depressed Skull Fracture: depth > thickness of cranium, dural penetration, pneumocephalus
Generally warrant admission to a surgical intensive care unit.
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