Intravenous anesthetics 3

Question 1

Choose the statements that demonstrate an accurate understanding of thiopental. Select 2
a. it causes a reflex tachycardia
b. prompt awakening is the result of hepatic metabolism
c. it provides neuroprotection against global ischemia
d. there is a sulfur molecule in the second position

Answer 1

a. it causes a reflex tachycardia
d. there is a sulfur molecule in the second position

Question 2

Barbiturates should be avoided in patients with

Answer 2

acute intermittent prophyria

Question 3

The mechanism of action of sodium thiopental is

Answer 3

GABA-A agonist

Question 4

The onset of action of sodium thiopental is

Answer 4

30-60 seconds

Question 5

The duration of action of sodium thiopental is

Answer 5

5-10 minutes

Question 6

The clearance of sodium thiopental is

Answer 6

liver

Question 7

The active metabolite of sodium thiopental is

Answer 7

none

Question 8

The induction dose of sodium thiopental is

Answer 8

2.5-5 mg/kg IV

Question 9

The respiratory effects of sodium thiopental include

Answer 9

decreased respiratory drive
histamine release can cause bronchoconstriction

Question 10

The CV effects of sodium thiopental include

Answer 10

hypotension
myocardial depression
preserves the baroreceptor reflex so can lead to reflex tachycardia

Question 11

The CNS effects of sodium thiopental include

Answer 11

decreased ICP
can cause hyperalgesia
decreased CMRO2
decreased cerebral blood flow
decreased EEG activity

Question 12

Intra-arterial injection of sodium thiopental can cause

Answer 12

intense vasoconstriction and crystal formation leading to tissue necrosis

Question 13

Treatment of intra-arterial injection of sodium thiopental includes

Answer 13

treatment with a vasodilator (phentolamine or phenoxybenazamine) or stellate ganglion nerve block (sympathectomy of upper extremity)

Question 14

_______ is the gold-standard for ECT. It decreases the seizure threshold and produces a better-quality seizure.

Answer 14

Methohexital

Question 15

Repeated doses of sodium thiopental can lead to

Answer 15

tissue accumulation–> prolonged wake up time + hangover effect

Question 16

Compared to propofol, what effect does thiopental have on hypotension?

Answer 16

it produces less hypotension than propfol

Question 17

Describe the neuroprotective effects of sodium thiopental?

Answer 17

focal ischemia: yes (examples include carotid endarterectomy, temporary occlusion of cerebral arteries)
global ischemia: no (example: cardiac arrest)

Question 18

Acute intermittent porphyria is made worse by stimulation of

Answer 18

ALA synthase
emotional stress
prolonged NPO status
CYP450 induction

Question 19

Signs and symptoms of acute intermittent prophyria include

Answer 19

GI: severe abdominal pain (most common & typically first), N/V
CNS: anxiety, confusion, seizures, psychosis, coma
PNS: skeletal muscle weakness (risk of respiratory muscle failure), bulbar weakness (risk of aspiration)

Question 20

What drugs should be avoided with acute intermittent porphyria?

Answer 20

barbiturates, etomidate, ketamine, ketorolac, amiodarone, calcium channel blockers, birth control pills

Question 21

Anesthetic management of acute intermittent porphyria includes

Answer 21

liberal hydration
glucose supplementation
heme arginate
prevention of hypothermia

Question 22

With acute intermittent porphyrias, regional anesthesia is not

Answer 22

contraindicated, but many clinicians avoid it since it might be difficult to distinguish block-related complications from an acute porphyria attack

Question 23

The methohexital induction dose is

Answer 23

1-1.5 mg/kg

Question 24

Phenobarbital is excreted

Answer 24

unchanged in the urine (the hepatic P450 enzymes metabolize all of the other barbiturates)

Question 25

Which anesthetic agent produces sedation that MOST closely resembles natural sleep?
a. dexmedetomidine
b. midazolam
c. propofol
d. ketamine

Answer 25

a. dexmedetomidine

Question 26

What is the mechanism of action of dexmedetomidine?

Answer 26

alpha 2 agonist–> decreased cAMP–> inhibits the locus coeruleus in the pons (sedation)

Question 27

What is the onset of action of dexmedetomidine?

Answer 27

10-20 minutes

Question 28

What is the duration of action of dexmedetomidine?

Answer 28

10-30 minutes

Question 29

What is the clearance of dexmedetomidine?

Answer 29

liver

Question 30

What is the active metabolite of dexmedetomidine?

Answer 30

None

Question 31

What is the loading dose of dexmedetomidine?

Answer 31

1 mcg/kg over 10 minutes

Question 32

What is the maintenance dose of dexmedetomidine?

Answer 32

0.4-0.7 mcg/kg/hr

Question 33

What are the respiratory effects of dexmedetomidine?

Answer 33

preserves respiratory drive

Question 34

What are the CV effects of dexmedetomidine?

Answer 34

bradycardia & hypotension
transient HTN can occur with rapid administration

Question 35

What are the CNS effects of dexmedetomidine?

Answer 35

sedation & analgesia
no change in ICP or CMRO2
decreased CBF

Question 36

What are other properties of dexmedetomidine?

Answer 36

anti-shivering properties
lowers risk of emergence delirium
limited effects on evoked potentials
can be used for preoperative sedation in children

Question 37

What is the pKa of dexmedetomidine?

Answer 37

7.1

Question 38

Describe why rapid administration of dexmedetomidine can cause hypertension.

Answer 38

this direct effect occurs before the centrally mediated reduction in SNS tone. Once the CNS effect kicks in, the central alpha-2 effect will overpower the peripheral alpha-2 effect

Question 39

Does dexmedetomidine provide reliable amnesia?

Answer 39

No