IV Anesthetics Flashcards
1
Q
What is the chemical name and class of Propofol?
A
2,6 - Diisopropylphenol
isopropylphenol
2
Q
What is the mechanism of action of propofol?
A
Direct GABA-A agonist -> ↑ Cl conductance -> neuronal hyperpolarization
3
Q
What is the induction and infusion dose of Propofol?
Are they based on LBW or TBW?
A
induction: LBW, 1.5-2.5 mg/kg
Maintenance: TBW, 25-200mcg/kg/min
4
Q
What is the onset and duration of propofol?
A
onset: 30-60 sec
duration: 5-10 minutes
5
Q
How is propofol metabolized?
A
Liver by P450 enzymes and extra hepatic metabolism (lungs)
6
Q
What does the preservative in Propofol contain?
A
EDTA
7
Q
Describe pharmacokinetics of propofol.
A
Blood concentration declines over time. Rapid distribution to VRG. Redistributes to muscle then fat.
8
Q
The concentration of propofol in the brain peaks at what time interval?
A
1 minute
9
Q
How does propofol affect... BP SVR venous tone myocardial contractility
A
all decrease
10
Q
How does propofol shift the CO2 response curve?
A
down and to the right (less sensitive to CO2)
11
Q
What effect does propofol have on hypoxic ventilatory drive?
A
inhibits hypoxic ventilatory drive
11
Q
How does propofol affect... CMRO2 Cerebral blood flow Intracranial pressure Intraocular pressure
A
decrease all
12
Q
What doses of propofol is used as an antipruritic and antiemetic effect?
A
antipruritic: 10mg
antiemetic: 10-20mg
13
Q
Can you give propofol to a patient with a egg allergy?
A
yes, they are likely allergic to the egg white. Propofol comes from the yolk
14
Q
What can long term propofol infusion cause? What is it?
A
propofol infusion syndrome. Starves cells of O2, particularly cardiac and skeletal
15
Q
What are some signs of propofol infusion syndrome?
A
bradycardia-> asystole, metabolic acidosis, rhabdo, enlarged liver,
16
Q
What are risk factors for propofol infusion syndrome?
A
dose > 4 mg/kg/hr (67 mcg/kg/min) Infusion duration > 48 hours Children > adults Inadequate oxygen delivery Sepsis Significant cerebral injury
17
Q
When should a syringe and infusion of propofol be discarded?
A
syringe: 6 hours
infusion: 12 hours
18
Q
Should branded or generic propofol be avoided in asthmatics and infants?
A
generic. due to preservatives
metabisulfite causes bronchospasm
benzyl alcohol should be avoided in infants
19
Q
How can propofol injection pain be avoided?
A
lidocaine before
larger vein
opioid before
20
Q
Fospropofol is (select 2) a lipid emulsion prodrug pain at injection site metabolized by alkaline phosphate
A
prodrug
metabolized by alkaline phosphate
21
Q
What IV induction agent causes genital and anal during on injection?
A
fospropofol
22
Q
What is the chemical name and class of fospropofol?
A
Phosphono-O-methyl-2,6-diisopropylphenol
Isopropylphenol
23
Q
Is fospropofol a lipid emulsion or aqueous solution?
A
aqueous solution. doesnt support bacterial growth
24
What is the mechanism of action of fospropofol?
Is a prodrug, metabolized to propofol by alkaline phosphatase. Slow onset and long duration
25
What is the induction and repeat dose of Fospropofol?
induction: 6.5mg/kg
| repeat bolus: 1.6mg/kg q4min
26
What is the onset and duration of fospropofol?
onset: 5-13 minutes
Duration: 15-45 minutes
27
How is fospropofol metabolized?
liver by P450 enzyme and extrahepatic metabolism (lungs)
28
What is the extraction ratio of propofol and fospropofol? What does this mean?
ER > 0.7
| Clearance is dependent on liver BLOOD FLOW.
29
What is the active metabolite of fospropofol?
propofol!
| Formaldehyde is metabolized to formate & excreted in urine
30
What is the chemical name and class of ketamine?
2-(o-Chlorophenyl)-2 (methylamino) cyclohexanone hydrochloride
Arylcyclohexylamine- Phencyclidine derivative
31
What kind of mixture is ketamine and its pKA?
racemic mixture
| pKA 7.5
32
What is the MOA of ketamine?
NMDA receptor antagonist
| dissociates the thalamus from the limbic system
33
What are secondary receptor targets of ketamine?
opioid, MAO, serotonin, NE, muscarinic, Na channels
34
```
What are the doses of ketamine?
Induction:
maintenance:
low dose infusion:
analgesia:
```
Induction: 1-2mg/kg
maintenance: 1-3mg/kg
low dose infusion: 1-3mg/kg
analgesia: 0.1-0.5 mg/kg
35
What is the IM and oral dose of Ketamine?
IM: 4-8mg/kg
oral: 10mg/kg
36
What is the IV and IM onset and duration of Ketamine?
IV: 30-60 seconds, IM: 2-4 minutes
DOA: 10-20 minutes, 60-90 min for full orientation
37
Where is Ketamine cleared from the body?
liver by P450 enzymes
| chronic use causes rapid escalation of tolerance
38
What is the active metabolite of ketamine? What is its potency?
norketamine, 1/3 - 1/5 the potency
| renal excretion
39
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What does ketamine do to...
SNS tone
Cardiac output
HR
SVR
Pulmonary vascular resistance
```
increase all
40
When is ketamine a myocardial depressant?
patient with depleted catecholamine stores or sympathetectomy
41
Is ketamine a better analgesic for visceral or somatic pain?
somatic
42
What IV induction agent is a great choice if the patient is actively wheezing?
ketamine, its a bronchodilator
43
How does ketamine alter the CO2 response curve and respiratory drive?
it doesnt!
44
What medication is prudent to give your patient after giving ketamine?
glycopyrrolate. It increases secretions
45
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How does ketamine affect....
CMRO2
Cerebral blood flow
ICP
Intraocular pressure
EEG activity
```
increases all
46
Why is ketamine contraindicated in eye surgery?
causes nystagmus
47
What is the best medication to give to prevent emergence delirium in a patient that received ketamine?
Midazolam before ketamine administration. Also diazepam
48
What are risk factors for emergence delirium from ketamine?
age > 15 years, females, ketamine dose > 2 mg/kg, hx of personality disorder
49
In order to prevent hyperalgesia following remifentanil infusion what IV induction agent can you give?
ketamine
50
Where does ketamine block central sensitization and wind up in the spinal cord?
dorsal horn
51
What can chronic ketamine use cause?
ulcerative cystitis
52
Ketamine should be avoided in what patient?
acute intermittent porphyria
53
Which IV induction agent undergoes the smallest amount of plasma protein binding?
ketamine
54
What is the chemical name and class of etomidate?
R-1-methyl-1-(a-methylbenzyl) imidazole-5-carboxylate Imidazole
55
How does an acidic pH and physiologic pH affect solubility of etomidate?
acidic pH: water soluble
| physiologic pH: lipid soluble
56
What are the two formulations of etomidate?
35% propylene glycol: venous irritation and pain
| lipid emulsion: less pain
57
What is the MOA of etomidate?
GABA-A agonist
58
What is the induction dose of etomidate?
0.2-0.4mg/kg
59
What is the onset and DOA of etomidate?
onset: 30-60 seconds
DOA: 5-15 minutes
60
How is etomidate cleared from the body?
P450 enzymes and plasma esterases
61
Is rapid awakening from etomidate caused by metabolism or redistribution?
redistribution off receptors
62
What are the cardiac effects of etomidate?
hemodynamic stable
slight decrease in BP
does not block SNS response to laryngoscopy
63
What effect does etomidate have on the respiratory system?
mild depression
64
How does etomidate affect...
CMRO2
CBF
ICP
decreases
65
Which IV anesthetic is most likely to cause PONV?
etomidate
66
What is a side effect of etomidate d/t imbalance between excitatory & inhibitory pathways in the thalamocortical tract?
myoclonus. Not seizure
67
Does etomidate increase the risk of seizures?
only if they have a history of seizures
68
What IV induction agent is useful for mapping seizure foci?
etomidate
69
What are the two enzymes that etomidate inhibits?
11-beta-hydroxylase & 17-alpha-hydroxylase
70
Why should etomidate be avoided in patients with sepsis, acute adrenal failure or Addisonian crisis?
decreases adrenocortical function for 5-8 hours
71
What induction agents should be avoided in patient with acute intermittent porphyria?
etomidate, ketamine
72
What barbiturate has a sulfur molecule in the second position?
thiopental
73
What barbiturates have a oxygen molecule in the second position?
methohexital, pentobarbital
74
Methohexital has a methyl group on the nitrogen atom. What does this cause?
lower seizure threshold and increases potency
75
Phenobarbital has a phenyl group at the 5 carbon, what does this do?
increases anticonvulsant effect
76
What is the chemical name and class of thiopental?
5-ethyl-5-(1-methylbutyl)-2-thiobarbituric acid
| Barbiturate
77
Is thiopental water or lipid soluble?
water soluble
78
What is the pH of thiopental? What is the danger of this?
pH 9. Precipitates if mixed with an acidic solution.
79
What does thiopental cause if given arterially?
vasoconstriction, crystal formation, tissue necrosis
80
What is the MOA of thiopental?
GABA-A agonist -> Depresses the reticular activating system in brainstem.
81
What are the different effects of low and high dose thiopental?
Low/normal dose: Increases the affinity of GABA for its binding site
High dose: Directly stimulates the GABA-A receptor
82
What are the adult and child doses of thiopental?
adult: 2.5-5mg/kg
child: 5-6mg/kg
83
What is the onset and DOA of thiopental?
onset: 30–60sec
DOA: 5–10min
84
Where is thiopental cleared?
P450 enzymes
85
What two IV induction agents is awakening determined by redistribution and not metabolism?
thiopental and etomidate
86
What is the active metabolite of thiopental?
normal dose: none
| high dose: phenobarbital
87
What medication is the gold stardard for use during an ECT?
methohexital
88
What is the mechanism of methohexital?
decreases seizure threshold and produces a better seizure
89
What is the induction dose of methohexital?
1-1.5mg/kg
90
What are the cardiovascular side effects of barbiturates?
hypotension and histamine release. Baroreceptor reflex remains intact
91
How does barbiturates shift the Oxygen-Hgb dissociation curve?
to the right. more unloading of O2
92
How do barbiturates affect:
CMRO2
CBF, ICP
EEG activity
decrease all
93
Do barbiturates cause global or focal ischemia?
focal
94
What is the most common and dangerous form of porphyria?
acute intermittent
95
What causes poryphria?
defect in heme synthesis that promotes accumulation of heme precursors
96
What causes an exacerbation of acute intermittent porphyria?
stimulation of ALA synthase, emotional stress, NPO, CYP450 induction
97
What drugs should be avoided in a patient with acute intermittent porphyria?
barbiturates, etomidate, ketamine, ketorolac, amiodarone, CCBs, birth control
98
What are presentation symptoms of acute intermittent porphyria?
abdominal pain (#1), psychiatric symptoms, delirium, seizures, neuropathy, & coma
99
What is the anesthetic management of the patient with acute intermittent poryphria?
liberal fluids, glucose supplements, heme arginine, prevent hypothermia
100
What is the treatment of intra-arterial injection of thiopental?
phentolamine, phenoxybenzamine
101
What is the chemical name and class of dexmeditomidine?
(S)-[1-(2,3-Dimethylphenl)ethyl]-1H-imidazole monohydrochloride
Imidazole
102
What is the pKA of dexmedetomidine?
7.1
103
What is the MOA of dexmedetomidine?
alpha 2 agonist. decreases cAMP, which inhibits the locus coeruleus in the pons causing sedation
104
what are the loading and maintenance doses of dexmedetomidine?
loading: 1mcg/kg over 10 minute
maintenance: 0.4-0.7 mcg/kg/hr
105
what is the onset and duration of dexmedetomidine?
onset of loading dose is 10-20 minutes
| duration 10-30 minutes after stopping
106
What is responsible for clearance of dexmedetomidine from the body?
Liver, P450 enzymes
107
Does dexmedetomidine have an active metabolite?
No
108
What are the most common side effects of dexmedetomidine?
HoTN and bradycardia
109
What is the mechanism for dexmedetomidine causing HTN after rapid injection?
peripheral alpha 2 stimulation. Central stimulation quickly overcomes peripheral alpha 2 stimulation
110
How does dexamethasone affect the respiratory system?
It doesnt. NO RESPIRATORY DEPRESSION
111
How does dexmedetomidine affect:
CBF
CMRO2
ICP
CBF decreases
CMRO2 not affected
ICP not affected
112
Where does dexmedetomidine produce analgesia?
dorsal horn of spinal cord. decreases substance P and glutamate release
113
What is the dose of dexmeditomidine for preop sedation for kids? When do you give it?
3-4mcg/kg 1 hour prior. Nasal or buccal route
114
What is the chemical name and class of midazolam?
8-chloro-6-(2-fluorophenyl)-1-methyl-4 H-imidazole[1,5-a][1,4]benzodiazepine
Benzodiazepine
115
What is special about the structure of midazolam and alterations in pH?
imidazole ring.
in acidic pH its H2O soluble
at physiologic pH its lipid soluble
116
What is the MOA of midazolam?
GABA-A agonist. Increases frequency of channel opening leading to neural hyperpolarization
117
GABA-A agonist increase channel open _____
| Benzos increase channel open _____
GABA-A agonist increase channel open time
| Benzos increase channel open frequency
118
What is the sedation dose, and induction dose of midazolam?
sedation: 0.01-0.1 mg/kg
induction: 0.1-0.4 mg/kg
119
What is the dose of oral midazolam for kids?
0.5-1 mg/kg
120
What is the onset and duration of midazolam?
onset: 30-60 seconds
duration: 20-60 minutes
121
How is midazolam cleared from the body?
liver by P450 enzymes
122
What is the active metabolite of midazolam?
1-hydroxymidazolam, 0.5x the potency
123
What are cardiac effect of induction doses of midazolam?
decreased BP and SVR
124
What medications given with midazolam potentiates the respiratory depression with induction doses?
opioids
125
What patients are very sensitive to induction doses of midazolam?
COPD due to respiratory depression from induction doses
126
What are CNS side effects of induction doses of midazolam?
decreased CMRO2 and CBF
127
What are the three A's of midazolam CNS side effects?
Anterograde amnesia
Anticonvulsant
Anxiolysis
128
What is the elimination 1/2 time of diazepam?
43 hours due to enterohepatic recirculation
129
What medications can be used to prevent emergence delirium from Ketamine?
midazolam and diazepam
130
Diazepam causes skeletal muscle relaxation, right?
correct
131
Amnestic effects of Lorazepam can last for how many hours?
6
132
Is Lorazepam a good choice to use as an anticonvulsant?
No, it has a slow onset
133
Rank the benzos from greatest to least potent?
Lorazepam > midazolam > diazepam
134
Do benzos cause antegrade or retrograde amnesia?
antegrade amnesia (memories after administration)
135
What is the additive in diazepam and lorazepam that causes venous irritation?
propylene glycol
136
What is the initial dose of Flumazenil given?
0.2mg IV
137
What is the MOA of flumazenil?
a competitive antagonist at the GABA-A receptor
138
What is flumazenil used to reverse?
benzodiazepines
139
Does Flumazenil increase SNS tone, anxiety, or neuroendocrine evidence of stress?
no
140
Does Flumazenil reverse the sedative or amnestic effects of benzos more?
the sedative effects more than the amnestic effects
141
Name that IV anesthetic!
Propofol
142
Name that IV anesthetic!
Fospropofol
143
Name that IV anesthetic!
Ketamine
144
Name that IV anesthetic!
Etomidate
145
Name that IV anesthetic!
Thiopental
146
Name that IV anesthetic!
Dexmedetomidine
147
Name that IV anesthetic!
Midazolam
