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Lindsays Flashcardlet > RE CH28 Part 2 > Flashcards

RE CH28 Part 2 Flashcards

1
Q

Which inhalation Anesthetics cause the greatest increase in cerebral blood flow?

A

Isoflurane, followed by sevoflurane and des.

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2
Q

CBF is unaltered with isoflurane MAC _____ to ____

A

0.6 to 1.1

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3
Q

With inhalation anesthetics at what MAC does the EEG become isoelectric?

A

2.5 MAC

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4
Q

What does N2O do to CBF, CMRO2, and ICP

A

Increases

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5
Q

Through which mechanisms do inhalation agents decrease cerebral perfusion pressure?

A

Decreasing map and increasing ICP

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6
Q

What are the effects of propofol on CBF and CMRO2?

A

Dose dependent decreases of 40-50%

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7
Q

What is the effect of etomidate on CMRO2 and CBF?

A

Reduces both. Decreases ICP without reducing CPP.

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8
Q

What are the effects of dexmetomidine on CMRO2 and CBF?

A

No change in CMRO2. Decreases CBF.

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9
Q

What is the effect of synthetic opioids on CBF and CMRO2?

A

CBF: Dose dependent decreases (to 25 mL/100g/min)

CMRO2: Dose dependent decreases (40 to 50%)

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10
Q

Which synthetic opioid produces the greatest decrease in MAP and ICP?

A

Alfentanil

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11
Q

Why should meperidine be avoided in the neurosurgical patient?

A

It’s metabolite normeperidine is a well-known convulsant

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12
Q

What is the effect of benzodiazepines on CBF, CMRO2 and ICP?

A

CBF: dose dependent decrease

CMRO2: dose dependent decrease

ICP: no change

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13
Q

What is the effect of Ketamine on CBF, CMRO2, and ICP?

A

CBF: Increase (60-80%)

ICP: Increase

CMRO2: Unchanged

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14
Q

List the intracranial contents.

A

Brain (12%)

Intracellular water (78%)

CSF (75 mL)

Blood (50 mL)

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15
Q

What is the total volume of intracranial contents?

A

1200 to 1500 mL

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16
Q

What is the equation for CPP?

A

CPP = MAP-ICP

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17
Q

What is the normal adult ICP?

A

5-15 mmHg

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18
Q

How does the intracranial compartment compensate for increases in mass (blood or tumors)

A

Decrease the CSF compartment (Increase in CSF absorption)

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19
Q

What is the gold standard for monitoring ICP?

A

Intraventricular catheter.

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20
Q

What ICP level is considered to be intracranial hypertension?

A

20 - 25 mmHg

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21
Q

What are the signs/symptoms of intracranial hypertension?

A

Headache, N/V, papilledema, focal neurological deficits, altered ventilators function, decreasing LOC, seizures, and coma.

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22
Q

What occurs when ICP exceeds 30 mmHg?

A

CBF progressively decreases and a vicious cycle is established:
-ischemia produces brain edema, which increases ICP, which further precipitates ischemia.

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23
Q

CBF decreases ______% for every 1 mmHg decrease in Paco2

A

4%

24
Q

What is the last resort treatment for intracranial hypertension?

A

Bilateral decompression craniectomy

25
Q

How does lowering Paco2 decrease ICP?

A

Respiratory alkalosis causes vasoconstriction which decreases CBF and ICP

26
Q

CMRO2 decreases ______% for every 1 degree centigrade decrease in body temperature.

A

7%

27
Q

Paco2 is approximately ______ mmHg higher than ETco2

A

2-5

28
Q

What pathologic changes cause a slowing of EEG activity?

A

When oxygen delivery is compromised.

29
Q

What effect do inhaled Anesthetics have on latency and amplitude of SSEPs?

A

Increased latency, decreased amplitude.

30
Q

What effect does fentanyl have on SSEP latency and amplitude?

A

Slight increase latency, slight decreased amplitude.

31
Q

What effect does propofol have on SSEP latency and amplitude?

A

Increase latency, no change in amplitude.

32
Q

What effect does ketamine and ethmoid ate have on SSEP latency and amplitude?

A

Increase both.

33
Q

What effect does dexmetomidine have on SSEP latency and amplitude?

A

No change

34
Q

What is the capillary pore size of the BBB?

A

0.7-0.9 nm

35
Q

What are fluid goals for supratentorial surgery?

A

Patients should be kept isovolemic, isotonic, and isooncotic.

36
Q

What is the fluid of choice for neurosurgery?

A

0.9 NaCl, LR should be avoided due to glucose content.

37
Q

What is a paradoxical air embolism?

A

Entry of air into the systemic circulation

38
Q

A PFO exists in what percent of the population?

A

30-35%

39
Q

What are the signs/symptoms of a venous air embolism (VAE)

A 
Pulmonary HTN
Hypoxemia
CO2 retention
Increased dead space ventilation
Decreased ETco2
40
Q

What is the most sensitive monitor for VAE?

A

TEE

41
Q

What is the treatment for VAE?

A
  1. Tell surgeon to flood the field
  2. Stop N20 and 100% O2
  3. Aspirated right atrial catheter
  4. Valsalva maneuver or compress jugular veins for 5-10 sec
  5. Position left lateral trendelenberg
42
Q

A 50% N2O concentration does what to air bubble volume? What about 70% concentration?

A

50% concentration doubles air volume

70% concentration quadruples the air bubble volume.

43
Q

What is a common surgical approach to pituitary tumors?

A

Transsphenoidal

44
Q

Should you hyperventilate for pituitary tumor surgery?

A

No. It will cause retraction of the pituitary into the sella causing difficult access

45
Q

What is the max dose of 1:100,000 epi for submucosal administration?

A

10 mL for 70 kg patient.

46
Q

What is the max dose for cocaine?

A

200 mg

47
Q

What dose of lidocaine should be administered to avoid coughing on emergence?

A

1.5 mg/kg

48
Q

What are the signs/symptoms of Subarachnoid hemorrhage?

A 
Intense headache in 85% of patients
Transient loss of consciousness in 45% of patients
N/V
Photophobia
Fever
Meningismus 
Focal Neuro deficits
49
Q

What is transmural pressure?

A

Differential pressure between MAP and ICP and represents the stress applied to an aneurysm wall.

Increases in blood pressure directly increase transmural pressure.

50
Q

Why should caution be taken when reducing transmural pressure?

A

Cerebral autoregulation may be impaired after SAH and reduction in BP may aggravate cerebral ischemia.

51
Q

What are the most common ECG changes seen with SAH?

A

T and ST segment changes.

52
Q

What is the incidence of rebleeding in the first days following SAH? This is associated with what mortality rate?

A

50% incidence of rebleeding

80% mortality rate.

53
Q

What is the leading cause of morbidity and mortality in patients with SAH after aneurysm rupture?

A

Cerebral vasospasm

54
Q

What is triple H therapy?

A

The most effective regimen to prevent neuro deficits secondary to cerebral vasospasm:

Hypertension, hypervolemia, and hemodilution (Hct 27-30%).

55
Q

What is the goal MAP in the face of aneurysm rupture?

A

40 to 50 mmHg

56
Q

What is the first and most rapidly effective therapy for increased ICP?

A

Hyperventilation.

Lindsays Flashcardlet (27 decks)

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