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BASIC > Neurological Emergencies > Flashcards

Neurological Emergencies Flashcards

1
Q

What is primary and secondary brain injury?

A

Primary: injury directly due to the insult.

Secondary: injury resulting from decreased O2 delivery.

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2
Q

What is the main mechanism of secondary brain injury?

A

Decreased O2 delivery to the brain.

Hyperglycaemia.

Electrolyte disturbances.

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3
Q

How do you calculate cerebral perfusion pressure?

A

CPP = MAP - ICP

Cerebral perfusion pressure is the difference between mean arterial pressure and intracranial pressure.

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4
Q

What are the two reasons why intracranial pressure is important?

A
  1. It is a major determinant of cerebral perfusion pressure.
  2. Raised ICP can result in herniation of the brain.
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5
Q

How do you reduce the volume of an oedematous brain?

A

Administer an osmotic diuretic (e.g. mannitol)

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6
Q

What is the mechanism of action of mannitol?

A

Mannitol is an osmotic diuretic, and therefore reduces brain oedema.

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7
Q

How do you reduce the volume of CSF?

A

Intraventricular drainage

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8
Q

How do you reduce the volume of intracranial circulating blood?

A

Hyperventilation - causes cerebral vasoconstriction.

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9
Q

What is the mechanism of action of hyperventilating a brain injured patient?

A

Hyperventilation causes cerebral vasoconstriction, which reduces intracerebral blood volume.

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10
Q

How rapid are the effects of mannitol?

A

Mannitol results in reduction of intracranial pressure within minutes.

Maximal effect is usually within 30 minutes or so.

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11
Q

Adverse effects of mannitol:

A

Can result in hypovolaemia (due to diuresis). Therefore only give mannitol if hypovolaemia has been corrected.

Renal failure.

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12
Q

What is hypertonic saline? What is its use in head injury?

A

Alternative to mannitol.

Useful in hypovolaemic patients as it increases circulating volume.

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13
Q

What are the pros and cons of hyperventilation?

A

Pro: reduces intracranial pressure

Con: reduces cerebral blood flow and perfusion

Therefore: only use hyperventilation if patient is showing signs of herniation, or if surgical evacuation has been unsuccessful.

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14
Q

What are the signs of herniation?

A

Hypertension
Bradyarrhythmias
Loss of brainstem reflexes (e.g. pupil reflexes)
Respiratory arrest
Dilated pupils

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15
Q

Target PaCO2 in hyperventilation

A

4 - 4.5 kPa

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16
Q

What are some extra measures that can be used in patients with raised ICP (other than osmotherpay, hyperventilation, and surgical evacuation)

A

Sedation, analgesia, paralysis (reduce cerebral O2 demand; prevent coughing and straining)

Nurse the patient head up 30 degrees

TXA (if due to traumatic head injury)

17
Q

What should be the target MAP in head injured patients?

A

> 90mmHg

18
Q

What is the best resuscitation fluid in head injured patients?

A

0.9% saline. Better than balanced crystalloids.

19
Q

What is the best resuscitation fluid in head injured patients?

A

0.9% saline. Better than balanced crystalloids.

20
Q

What should be the target intracranial pressure?

A

<20mmHg

21
Q

What shoudl be the target cerebral perfusion pressure?

A

> 60mmHg

22
Q

What anti-seizure medication should be given to prevent fits in head injured patients?

A

Prophylactic pheytoin.

23
Q

What medication should be used to treat HTN in subarachnoid haemorhage?

A

Labetolol

24
Q

What do fixed dilated pupils indicate in a seizure?

A

Fixed and dilated pupils are a feature of generalised convulsions.

They do not necessarily indicate herniation.

25
Q

What investigations should be ordered in a seizing patient?

A

FBC
U&Es
LFTs

Glucose
Calcium and magnesium
Anti-epileptic drug levels
Blood gas
Urinalysis

Consider:
- Toxicology screen
- CT scan
- LP

26
Q

Immediate management of status epilepticus

A

Take blood, treat hypoglycamia

Adminster O2

Left lateral position

27
Q

What benzodiazapine treatment is preferred in status epilepticus?

A

Lorazepam 0.1mg/kg IV (has longest duration of action)

or

Midazolam 10mg IM

28
Q

Lorazepam vs diazepam vs midazolam in status epilepticus

A
  1. Lorazepam is drug of choice (longer duration of action)
  2. If no IV access, give midazolam 10mg IM
  3. Otherwise diazepam 0.2mg/kg is less preferable (must be followed by phenytoin)

BASIC (21 decks)

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