Outline the strategies, with the rationale, to reduce the likelihood of secondary neurological injury after brain trauma. Give the specific parameters/targets where appropriate.

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College Answer

Strategy

Rationale

Endotracheal intubation

Prevention of hypoxaemia by preventing airway obstruction and/or aspiration, facilitates mechanical ventilation

Controlled mechanical ventilation

O2 saturation >95%

PaCO2 32 – 38 mmHg (4.2 –

5.0 kPa)

Avoidance of hypoxaemia, 

Avoidance of hypercarbia which can lead to cerebral vasodilation and increased ICP

Avoidance of hypocarbia with consequent cerebral vasoconstriction and relative ischaemia

Cervical spine immobilisation

Cervical spine injury is commonly associated with traumatic brain injury

Maintain an adequate blood pressure

Systolic BP >110

MAP 80-120 if CPP measured and ICP>20

Hypotension is associated with poorer neurological outcome

Hypovolaemia is common in trauma patients due to associated injuries

Avoid the use of albumin for fluid resuscitation

Albumin is associated with poorer outcomes in patients with TBI

Avoid cerebral venous hypertension

Care with ETT tapes

C-spine collars

Elevate head of bed 30-45o

Obstructed venous drainage can contribute to intracranial hypertension

Maintain normothermia  Temperature 36-37o

Elevated temperature increases cerebral metabolic demand

Hypothermia has not yet been shown to be associated with improved outcomes 

Maintain normoglycaemia  BSL 6-10 mMol/L

Hypoglycaemia exacerbates cerebral injury

Avoid hyponatraemia  Na 140-145 mMol/L

Hyponatraemia can contribute to cerebral oedema and raised intracranial pressure

Early       detection               of            surgically correctable secondary lesion

ICP monitoring

Low threshold for repeat CT scan if deterioration in clinical neurological state

Early identification of a surgically correctable lesion

Reaccumulation of extra-axial collection

Hydrocephalus

New intraparenchymal haemorrhage

Surgical intervention may prevent further neurological damage

Monitoring of and treatment for intracranial hypertension

 ICP <20

Strategies to treat intracranial hypertension (in addition to those mentioned above)

Sedation

Neuromuscular paralysis

Induction of mild hyperosmolar state

Detect and treat seizures

Convulsive and non-convulsive epileptic seizures, increase cerebral metabolic demand

Discussion

Neuroprotective measures in traumatic brain injury are discussed in great detail elsewhere.

Other chapters of interest would have to include

In brief:

Maintaining cerebral oxygen supply:

  • Normoxia: keep the PaO2 above 60 mmHg
  • Normotension: measure the MAP, and keep the systolic above 90mmHg
  • Intracranial Pressure monitoring: keep it under 20mmHg
  • Cerebral perfusion pressure: keep it 50-70mmHg
  • Cerebral oxygenation monitoring:keep the SjO2 >50%, and PbrO2 >55mmHg
  • Managing increased intracranial pressure for which there is a variety of strategies:
    • Draining the EVD ( about 20ml/hr, max)
    • Positioning the head straight
    • Removing the C-spine collar
    • Sedation :
      • Propofol sedation to decrease distress and thus decrease ICP
      • Barbiturate coma if other methods of lowering ICP have failed
      • Analgesia to prevent increased ICP in response to suctioning and routine care
    • Paralysis
    • Osmotherapy
    • Controversial measures
      • Decompressive craniectomy
      • Hypothermia
      • Dexamethasone

Decreasing cerebral oxygen demand:

  • Sedation
    • Propofol sedation to decrease distress and thus decrease ICP
    • Barbiturate coma if medical and surgical methods of lowering ICP have failed
  • Analgesia - opioid selection is irrelevant, but opiate boluses increase ICP
  • Seizure prophylaxis is infrequently indicated, and the course is 7 days only

Controversial measures:

  • Decompressive Craniectomy
  • Hypothermia