neurological emergency

Question 1

Discuss primary injury and resultant zones

Answer 1

Primary injury is the initial insult 
consists of three lays 
1) un-salvageable injury 
2) penumbra or salvageable area if secondary injury is prevented 
3) unaffected tissue

Question 2

Discuss secondary injury

Answer 2

Multiple causes but perhaps the most important is hypoxaemia – may be due to reduced delivery of o2 systemically or may be specific to brain

Should be noted it is impossible to achieve appropriate supply to cerebrum if systemically compromised so resus should focus on systemic resussitation initially then to specific for neuro

Hyperglycaemia and electrolyte disturbance may also contribute to secondary injury

Question 3

Discuss cerebral perfusion pressure

Answer 3

CPP = MAP - ICP

Question 4

Discuss the monroe-kelly doctrine

Answer 4

ICP is equal to CSF + Brain tissue + blood
These contents are in an inclosed space so increase in any of them will require a decrease in the other to maintain normal pressure usually reduction in CSF – once the compensatory threshold is reached further increase will increase ICP

Question 5

Discuss osmotherpay

Answer 5

Osmotic diuretic can reduce edema in brain tissue
Mannitol reduces ICP within minutes and reaches maximum within 20-40 minutes

usual dose is 0.25-1mg/kg over 5 minutes followed by .25-.5 every 6 hours

Can cause hypotension if volume deplete
may also cause AKI (higher risk of osmalality is greater then 320)
reverse osmotic shift

Can use hypertonic saline 3% which is particulalry useful in hypovolaemic patients

Question 6

Discuss the use of hyperventilation in treatment of ICP

Answer 6

Hyperventilation will reduce ICP but at the expense of cerberal blood flow as a decrease in co2 will cause vasoconstriction– it therefore illogical to use hyperventilation to treat ICP

Can aim for low normal co2

Question 7

Discuss other measures for treatment if ICP

Answer 7

• Sedation and intubation reduced cerbebral oxygen demands and prevent coughing and straining which both increase ICP
• Nurse in 30 degree head up to improve venous drainage
• Maintian normothermia to prevent raise in metabolic rate
• prevent hyperglycaemia which compounds neurological injury

Question 8

Discuss indication for intracranial pressure monitoring

Answer 8

• Severe brain injury (GCS3-8 after resus)
• an abnormal CT brain
• or at least 2 of the following
• ->40 years old
• -motor posturing
• • arterial hypotension

Insertion of an intraventricular pressure monitor has the advantage of allowing drainage of CSF in order to control ICP

ICP should be kept below 20-25mmhg and CCP should be greater then 60mmhg

Question 9

Discuss sequence of management for traumatic brain injury

Answer 9

1) evacuation of lesion (extrdural, sub dural, hydrocephalus)
2) analgesia sedation to reduce metabolic demand, normothermia, normoglycaemia and seizure prevention with phenytoin
3) drain CSF if intraventricular drain is in-situ
4) hyperventilate to 30-35
5) mannitol or hypertonic saline

Question 10

Discuss management of subarachnoid haemorrhage

Answer 10

1) pressure control aim CPP greater then 60mmhg with a systolic less then 150 labetalol which has both alpha and beta blockade is useful
2) Too low pressure increases secondary injury to high increase chance of rebleeding
3) if aneurysmal bleed nimodipine should be given if not hypotensive

Question 11

Define status epilepticus

Answer 11

Continuous seizure for more then 5 minutes or multiple seizures without full recovery in between lasting greater then 5 mintues

It should be noted that fixed dilated pupils are a feature of generalized seizure and does not indicate herniation

Question 12

Discuss treatment of generalized status epilepticus

Answer 12

Generalised status should be treateed urgently because electrical seizure activity causes neuronal damage with or without motor activity. Seizure activity also becomes more difficult to terminate as it continues

Resus

• ABC
• left lateral position
• give 02
• if persistent or patient becomes cyanosed consider ETT

Hypoglycaemia

• give 50ml 50%glucose and 100mls thiamine in adults
• in children use 25% 2ml/kj

Benzo

• loraz IV is the agent of choice due to its longer antiepileptic action 0.1mg/kg if IV access already available
• otherwise 5-10mg of IV midaz can be used

Second line treatment

• leviteracam
• phenytoin loading

Question 13

Discuss treatment of refractory seizures

Answer 13

Intubation and ventilation
Infusion of either thiopentone, propofol or midaz to cease clincal and electrical seizure activity

Thiopentone can result in prolonged sedation if after infusion is stopped

midaz shows marked tachyphylaxis and doses will need to be increased to maintain sedation

Propofol infusion is associated with propofol infusion syndrome

Question 14

Discuss propofol infusion syndrome

Answer 14

It is characterised by acute refractory bradycardia and at least one of the followin

• rhabdomyolisis
• metabolic acidosis
• hyperlipidaemia
• enlarged liver