Raised ICP Flashcards

1
Q

What is normal intracranial pressure in an adult?

A

0-10 mmHg at rest

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2
Q

When is treatment required for raised ICP?

A

when it exceeds 15-20 mmHg for >5 min

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3
Q

What are 7 symptoms and signs of raised intracranial pressure?

A
  1. Headache and vomiting
  2. Focal neurological signs
  3. Seizures
  4. Papilloedema
  5. Impaired level of consciousness: mild confusion to coma
  6. Signs of brain shift
  7. Cushing’s triad: bradycardia, hypertension, Cheyne-Stokes (irregular) breathing
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4
Q

What is the nature of headache in raised intracranial pressure?

A

worse in mornings, exacerbated by bending, associated with vomiting

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5
Q

When might there be focal neurological signs in raised ICP?

A
  • if space-occupying lesions, and some metabolic conditions e.g. liver failure
  • also false localising signs e.g. cranial nerve VI palsy
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6
Q

What is the false localising sign in raised ICP?

A

cranial nerve VI palsy (unable to abduct eye on affected side due to long intracranial course)

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7
Q

What are 3 things associated with seizures in raised ICP?

A
  1. Space occupying lesion
  2. CNS infection
  3. Metabolic encephalopathies
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8
Q

What is the only situation when papilloedema is present in raised ICP?

A

if there is CSF obstruction

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9
Q

What are 2 examples of signs of brain shift?

A
  1. Decreasing level of consciousness
  2. Brainstem dysfunction
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10
Q

When does the Cushing triad occur in raised ICP?

A

late signs (bradycardia, hypertension, Cheynes-Stokes breathing)

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11
Q

What are 8 causes of raised intracranial pressure?

A
  1. Head injury with intracranial haematoma/brain swelling/contusion
  2. Stroke: haemorrhage, major infarct, venous thrombosis
  3. Metabolic: hepatic or renal failure, DKA, hyponatraemia
  4. CNS infection (abscess, encephalitis, meningitis, malaria)
  5. CNS tumour
  6. Status epilepticus
  7. Hydrocephlus
  8. IIH
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12
Q

What are 3 types of stroke which may lead to raised ICP?

A
  1. Haemorrhagic
  2. Major infarct
  3. Venous thrombosis
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13
Q

What are 4 metabolic causes of raised ICP?

A
  1. Hepatic failure
  2. Renal failure
  3. DKA
  4. Hyponatraemia
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14
Q

What are 4 types of infection which may cause raised ICP?

A
  1. Abscess
  2. Encephalitis
  3. Meningitis
  4. Malaria
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15
Q

What are 2 things which can help with assessment of severity of raised ICP?

A
  1. GCS score (see image attached)
  2. Signs of brain shift and brainstem compromise
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16
Q

What are 6 aspects of the management of raised ICP?

A
  1. Stabilise patients
  2. Active means of reducing ICP
  3. Attempt to make diagnosis
  4. Treat factors which may exacerbate raised ICP
  5. Observe for signs of deteriorate, and attempt to reverse them
  6. Consider specific therapy
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17
Q

What are 7 aspects of stabilisation of the patient with raised ICP?

A
  1. Open airway by lying patient on side
  2. Give oxygen
  3. Take ABG
  4. Intubation and mechanical ventilation may be necessary due to respiratory compromise
  5. Correct hypotension
  6. Treat seizures
  7. Examine rapidly for signs of head injury
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18
Q

How should hypotension be corrected in raised ICP? 2 aspects

A
  1. volume expansion with colloids or infusions of inotropes (e.g. digoxin, dobutamine)
  2. fluid restriction to 1.5-2L a day
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19
Q

What monitoring must be performed when correcting hypotension with colloid or an inotrope infusion?

A

CVP (central venous pressure) and PAWP (peripheral capillary wedge pressure)

PAWP estimates left ventricular end-diastolic pressure

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20
Q

What fluid restriction should be performed if there is hypotension with raised ICP?

A

fluid restriction to 1.5-2L per day

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21
Q

What are 8 blood tests to perform when stabilising a patient with raised ICP?

A
  1. Glucose: DKA, HHS, liver failure(low)
  2. U+Es: potassium, hyponatraemia from SIADH, hypernatraemia from diuretic-induced dehydration
  3. LFTs
  4. Albumin
  5. Clotting studies
  6. Ammonium: to assess lvier function
  7. FBC
  8. Blood culture
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22
Q

What are 7 types of measures to reduce ICP that may be of benefit, deending on the cause?

A
  1. Elevate head of bed to 30o
  2. Hyperventilation
  3. Mannitol
  4. Corticosteroids: oedema around SOLs
  5. Fluid restruction to 1.5-2L/day
  6. Cooling to 35oC to reduce cerebral ischaemia
  7. Avoid/treat hyperglycaemia
23
Q

What must be excluded before elvation of the head of the bed to reduce ICP?

A

cervical spine injury

24
Q

Why should you elevate the head of the bed in raised ICP?

A

to promote venous drainage

25
Q

Why should hyperventilation be performed in raised ICP?

A

so that PaCO2 is kept between 3.7 and 3.9kPa and will promote cerebral vasoconstriction and lower cerebral volume

26
Q

What is required for hyperventilation to happen and lower ICP?

A

intubation and paralysis

27
Q

What is a risk of hyperventilation as a treatment for raised ICP?

A

may compromise cerebral circulation

28
Q

In which group of patients is hyperventilation no longer a recommended treatment for raised ICP?

A

patients with liver failure

29
Q

Who should you discuss with before hyperventilation is performed for raised ICP?

A

local ITU

30
Q

What is the recommended initial dosage of mannitol?

A
  • 0.5-1g/kg over 10-15min (250ml of 20% solution for an average adult)
31
Q

Within what time frame does mannitol take effect and how long will it last?

A

within 20 min; should last for 2-6h

32
Q

Subsequent to the initial dosage of mannitol, what doses should subsequent administrations be given at?

A

boluses of smaller doses, 0.25-0.5g/kg given every few hours

33
Q

What monitoring must be performed when giving mannitol and why? What is the aim?

A
  • U+Es and serum osmolality
  • profound diuresis may result
  • serum osmolality should not be allowed to rise over 320 mosm/kg
34
Q

When are corticosteroids of benefit when treating raised ICP?

A

reducing oedema around space-occupying lesions (not for stroke or head injury)

35
Q

What dose/route/rate of corticosteroid is given for ICP due to space occupying lesions?

A
  • dexamethasone: loading dose 10mg IV
  • may be followed by 4-6mg every 6 hours PO/via NG tube
36
Q

Why must hyperglycaemia be avoided/ treated in raised ICP?

A

it exacerbates ischaemia

37
Q

What often makes an underlying diagnosis obvious in raised ICP?

A

history

38
Q

What features suggest an underlying structural cerebral lesion is the cause of raised ICP?

A

focal neurological signs or focal seizures (but these may also occur in hepatic or renal failure)

39
Q

What causes of raised ICP are suggested by meningism?

A

SAH or meningitis

40
Q

What investigation must be performed in all patients suspected of having raised ICP and when?

A

CT scan - before LP is considered

41
Q

If a lumbar puncture is considered as an investigation for raised ICP what must be done first?

A

discuss with senior colelague and/or neurologist - risk of coning (downward cerebellar herniation)

42
Q

What investigation may help to detect metabolic causes of raised ICP?

A

blood sent for analysis

43
Q

What are 6 factors to treat which exacerbate raised ICP?

A
  1. Hypoxia/hypercapnia: ABGs
  2. Inadequate analgesia, sedation, muscle relaxation, hypertension
  3. Seizures
  4. Pyrexia: paracetamol + active cooling
  5. Hypovolaemia
  6. Hyponatraemia
44
Q

What should the approach to treating hypertension in raised ICP be?

A

should not be treated aggressively

45
Q

What can rapid lowering of blood pressure in raised ICP result in?

A

watershed/border zone cerebral infarcts

46
Q

What is an important aspect of treating seizures in patients with raised ICP?

A

not always easy to identify in paralysed patients

47
Q

How can pyrexia exacerbate raised ICP?

A

increases cerebral metabolism and therefore causes cerebral vasodilatation

appears to increase cerebral oedema

48
Q

What is usually the cause of hyponatraemia in raised ICP? What else can cause it?

A

usually result of fluid overload

SIADH

49
Q

What is the treatment of SIADH, to prevent hyponatraemia from exacerbating raised ICP?

A

desmopressin 1-4 micrograms IV daily

50
Q

What are 2 examples of surgical interventions for raised ICP once the cause has been identified?

A
  1. surgery to decompress brain
  2. insert ventricular shunt to drain CSF
51
Q

What is the approach to management of raised ICP if there is no specific therapy that’s appropriate e.g. contusion following head injury?

A

optimise patient’s condition while awaiting recovery

52
Q

What is cerebral perfusion pressure (CPP) and how is it calculated?

A

net pressure gradient causing cerebral blood flow to the brain

CPP = mean arterial pressure - ICP

53
Q

What does invasive ICP monitoring involve?

A

catheter placed into lateral ventricles of the brain to monitor pressure

54
Q

What are 2 additioanl benefits of invasive ICP monitoring?

A
  1. Can take CSF samples
  2. Drain small amounts of CSF to reduce pressure