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adv princip II exam 3 F (7/13) > neuro objectives 7-11 > Flashcards

neuro objectives 7-11 Flashcards

0
Q

7b.
1. Identify components of intracranial compliance (including curve)
2. what happens to compliance once compensatory mechanisms have been exhausted?
3. Where does that change on the intracranial volume-pressure curve?

A
  1. Intracranial compliance depends on “compensatory mechanisms” such as
    - decreasing CSF production
    - increased CSF absorption-
    - displacing CSF
    - cerebral vasoconstriction
  2. Intracranial compliance decreases significantly once maximum intracranial volume has been reached.
  3. The curve stays relatively flat as compensatory mechanisms come into play; once the “knee” of the curve is reached (i.e. compensatory measures have been exhausted), pressure increases greatly.
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1
Q

7a. Identify the components of ICP.

A 
components of ICP:
1. cerebral blood flow
2. brain
3. CSF
(all against the restriction of the skull (cranial vault))
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2
Q

7c. Identify components of ELEVATED ICP

- what causes minor transcient increases in ICP?

A
  1. Swelling of brain parynchema
  2. blockage of absorption of CSF or increased production of csf
  3. vasodilation of cerebral vessels
  4. mass effect (tumor)
    - coughing, valsalva
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3
Q
  1. Describe 5 methods to decrease ICP:
A
  • this is done by:
    1. decreasing cerebral blood flow (via blood pressure or controlling co2 levels (keeping CO2 30-35 mmHg)
    2. decreased CSF (via ventriculostom drain)
    3. removal of the part of skull (craniectomy)
    4. debulking (removal of brain-(tumor debulking))
    5. decreasing brain swelling (diuretics, hypertonic solutions)
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4
Q

9a. dosages for induction drugs commonly used during neurosurgery
(Calculate doses / recognize the implications of their use).

A
  1. Thiopental: 125-150 mg boluses
  2. Propofol: 50-300 mcg/kg/min gtt
  3. Etomidate
  4. AVOID IF POSSIBLE (unless trauma): Ketamine (increases ICP
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5
Q

9b. dosages for VAs commonly used during neurosurgery

Calculate doses / recognize the implications of their use

A
  1. nitrous oxide: up to 70%:
  2. Isoflurane (forane): 0.5-1 MAC: decreases amp. of SSEPs; increases amp. VERs: )only VA that can produce an isoelectric line at 1-2 MAC)
  3. Des & Sevo: 0.5-1 MAC;
    4.
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6
Q

9c. dosages for narcotics commonly used during neurosurgery

Calculate doses / recognize the implications of their use

A
  1. Fentanyl: 0.5-3 mcg/kg/hour (during EEG monitoring); (5-10 mcg/kg for induction)
  2. sufentanyl:
  3. remifentanil: (1-2 mcg/kg for induction)
  4. dexmetatomidine:
  5. Morphine: 0.1-0.3 mg/kg loading dose (not the best for neuro d/t poor lipid solubility)
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7
Q

9d. dosages for drugs commonly used during neurosurgery to BLUNT CV EFFECTS of laryngoscopy:
(Calculate doses / recognize the implications of their use).

A
  1. lidocaine 2%; 50-100 mg
  2. esmolol: 40 mg (beta blocker; reduces rate more than BP)
  3. labetolol: 5-10 mg (beta blocker; alpha and beta antagonist)
  4. hydralizine: 5-10 mg (central acting antihypertensive -onset 10 min)
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8
Q

9e. dosages of steroids commonly used during neurosurgery

Calculate doses / recognize the implications of their use

A

Decadron-corticosteroid-usual dose=16-20 mg
axn: decreases lysosomal action, stabilizes membranes, scavenges free radicals, promotes electrolyte and water excretion from brain, restores BBB, enhances cerebral electrolyte transport

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9
Q

9f. dosages for DIURETICS commonly used during neurosurgery

Calculate doses / recognize the implications of their use

A
  • -Mannitol 20%: 0.5-1 gram/ kg: osmotic diuretic; large molecular weight (does not cross BBB); caution in CHF patients (increases intravascular volume quickly) (onset 10-15 minutes; duration 6 hours)
  • -loop diuretics: will usually be used with CHF patients. slower onset than osmotic (onset: 30-45 minutes for ICP reduction)
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10
Q

10a. What are Ketamine’s effects on:
- ICP
- CBF
- CMRO2.

A

effects of ketamine on

  • ICP: increases (unless used with other sedatives)
  • CBF: increases (by vasodilating vessels but not if used with other sedatives)
  • CMRO2: only increases in limbic structures (not in main structures)
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11
Q

10b. What effects do opioids have on:
- ICP:
- CBF:
- CMRO2.

A
  • effects of Fentanyl, Remifentanil, sufentanil on:
  • ICP:decrease (but apnea cauusing increased CO2 can offset this)
  • CBF:minimal
  • CMRO2.: minimal
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12
Q

10c1. What effect do alpha adrenergic agonists have on:
- ICP
- CBF
- CMRO2.
10c2. what are the positive attributes of precedex for neuro surgery?

A

10c1.
-effects of Dexmetomidine (precedex) on:
-ICP: decreases (by decreasing CBF)
-CBF: decreases (without affecting oxygenation)
-CMRO2: little to no change
10c2.
++ dexmetomidine is considered neuroprotective
++ good for awake craniotomies
++ decreases IV and VA anesthetic needs
++ good for sedation, anangesia and anxiolysis

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13
Q

10d1. What are the effects of benzodiazepines on:
- ICP
- CBF
- CMRO2.
10d2. which benzo is the choice BDZ? why?
10d3. what is the caveat of using versed?

A

10d1.
-effects of benzos on:
decreases CBF
decreases CMRO2.
(? decreases ICP (d/t decreased CBF))
10d2: versed—d/t shorter half life than ativan and valium
10d3. versed can decrease BP which decreases CPP; also versed 1/2 life can prolong awakening when given in high doses.

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14
Q

10e1. What are the effects of BARBITURATES on:
- ICP
- CBF
- CMRO2.
10e2. what are other effects?
10e3. how does brevital differ from thiopental?

A

10e1. -effects of BARBS on:
decreases ICP by facilitating CSF reabsorption
decreases CBF
decreases CMRO2
10e2. also cause hypnosis
10e3. Brevital decreases seizure threshold at low doses and can induce seizures (at higher dose, it is the same as thiopental)

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15
Q

10f. Recognize the effects of lidocaine on:
- ICP
- CBF
- CMRO2.
10f2. what is the good thing about the effects of lidocaine on CBF?

A 
10f1.effects of lidocaine on:
decreases ICP
decreases CBF 
decreases CMRO2.
10f2. decreases CBF without any hemodynamic effects
16
Q

10g. What are Etomidate’s effects on:
- ICP:
- CBF:
- CMRO2:
- CSF:

A

decreases ICP
decreases CBF
decreases CMRO2 (more at cortex)
decreases CSF production (& increases absorption)

19
Q

-what doctrine explains ICP?

-

A

monroe kellie doctrine explains that if one of these three factors increases, that one must decrease (except for the brain in most cases)

20
Q
  1. which opioids are not the best for neuro cases?

2. why?

A
  1. morphine and demorol
  2. –morphine is poorly lipid soluble and therefore does not enter the brain well
    - —demorol can cause cardiac depression and accumulation of normeperidine (which causes seizures)
21
Q

what are issues with nitrous and neuro cases?

A

nitrous oxide: up to 70%:

  1. decreases amp of SSEPs;
  2. decreases amp of VERs
  3. most often avoided d/t increasing ICP(potent vasodilator) by increasing CBF
  4. some feel that these interfere with EEGs because it does increase frequency and amplitude of bursts
  5. increases CBF considerably when used with other VAs (dont use with other VAs)
  6. can enlarge Pneumocephalus or VAE (venous air embolism)
  7. action of N20 on CBF can be reduced with hyperventilation or IV agents
22
Q

what are issues with Isoflurane with neuro cases?

A

Isoflurane (forane): 0.5-1 MAC:

  1. decreases amp. of SSEPs;
  2. increases amp. VERs:
  3. only VA that can produce an isoelectric line at 1-2 MAC)
23
Q

when should you avoid nitrous if you have a brain mass or swelling?

A

Nitrous is a potent cerebral vasodilator and can increase cerebral blood flow and ICP like any other agent, but it also increases CMRO2 d/t stimulatory effects.

25
Q

10f1. Recognize the effects of vasopressors on:
- ICP
- CBF
- CMRO2
10f2. if ___ is intact, what vasopressors do not affect CBF?

A

10f1. vasopressors effects on:
- ICP: ?
- CMRO2: ?
- increase CBF (by increasing MAP and thus CPP) however:
10f2. If blood brain barrier is intact dopa, neo and levo do not increase CBF

26
Q

10h1. What are vasodilator’s effects on:
a) which drug is used most? why?
b) what is the downside of vasodilators on ICP?
CBF:
ICP:

10h2: what are vasodilators used for in brain trauma or SAH?

A

a) nipride is used more than nitro d/t rapid onset and easy titration
d/t fact that -nipride causes direct and rapid cerebral vessel dilation
b)increases ICP in patients with decreased intracranial compliance

-nitro increases CBF and ICP more than sodium nipride:

27
Q

Propofol and neuro cases:

  1. Pros:
  2. Cons:
A
  1. Pros:
    a. has a short 1/2 life, means quicker wake up?
    b. has direct antioxident action which is benificial to combat ischemia after strokes
  2. Cons:
    a. can cause hypotension and cardiac suppression which can decrease cerebral perfusion (CPP)
    b. grows bacteria
    c. can cause propofol infusion syndrome
31
Q
  1. State the potential complications associated with the sitting position during a craniotomy.
A

COMPLICATIONS OF SITTING CRANI:

  1. VAE d/t open venous sinuses with sinus above heart
  2. hypoperfusion of circle of willis d/r orthostatic hypotension
  3. POVL d/t hypoperfusion from hypotension
49
Q

why should you give barbiturates (especially thiopental) during clipping?

A

barbiturates offer brain protection during clipping (by decreasing CMRO2, CBF, and brain activity)

adv princip II exam 3 F (7/13) (3 decks)

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