Exam I - Anesthetics Flashcards
What is the function of the thalamic circuit?
-sensory processing
-attention
What is the function of the thalamocortical circuit?
-conciousness
-awareness
What is the function of the hippocampal network?
-memory
________ Receptors & ________ receptors also mediate fast excitatory impulses but have little anesthetic sensitivity
-AMPA
-Kainate
What 2 neurotransmitters bind to NMDA receptors?
-Glutamate
-Glycine
What gas effects the NMDA receptor?
N2O
Although the NMDA is a _______-gated ion channel, it is also sensitve to the _______ across the membrane containing the receptor
-Ligand-gated
-voltage
_______ blocks the ion channel on the NMDA receptor until membrane depolarization occurs
-Mg2+
(t/f) NMDA receptors must be activated before they can be antagonized
True
*Ketamine binding site is same location as Mg2+ that blocks the ion channel. Have to remove the Mg2+ through activation of the receptor to allow antagonists to bind.
What is the only anesthetic than can be used soley for GA that has analgesic properties?
Ketamine
*Dexmedetomidine (Precedex) is the only other sedative that has analgesic properties but it can’t be used as sole agent for GA
The _____ molecular position on barbituate molecules is responsible for the _______ effect of the drug. __________ sidechains have a greater effect than _________ chains
-C5
-hypnotic effect
-Branched sidechains > straight chains
What drug has a Phenyl Group @ C5
Phenobarbitol
What drug has a Methyl Group @ N1
Methohexital
What drug has a Sulfer atom @ C2
-Sodium thiopental
*aka Thiobarbituate
__________ was THE intravenous induction agent for anesthesia prior to Diprivan (Propofol).
Production in the U.S. stopped in 2010.
*BLUE BOX
Thiopental
Most important determinant of awakening
Redistribution to inactive, poorly perfused tissues
Onset of action of Sodium Thiopental (Pentothal)
30-60 sec
Onset of action of Methohexital (Brevital)
Immediate
*maximal brain uptake in 30 sec
The time to achieve a 50% reduction in concentration after stopping a continous infusion
Context-sensitive half-time
What 2 drugs (maybe 3) are contraindicated in Hypersensitivity/Intermittent
Porphyria?
-barbiturates
-etomidate
Nagelhout - includes Benzos (word for word)
What 2 drugs cause increased incidence of myoclonus?
-Barbiturates (methohexital)
-etomidate
What drugs increases frequency of Cl- channel opening via GABAa receptor stimulation
Benzos
Barbiturates have a _____ context-sensitive half-time
Prolonged
Barbiturates exhibit ______ order kinetics
Zero order
Zero order kenetics means what
Drug is eliminated per unit/time
*ex. - 5mg/hr
DOA of thiopental
*Red/bolded in PP
5-30 min
DOA of methohexital
*Red/bolded in PP
4-7 min
Rectal induction dose of methohexital
*Red/bolded in PP
25 mg/kg
Sodium thiopental (pentothal) has ___________ effects
*bolded in red on Dr. B’s PP chart
anticonvulsant effects
Methohexital (brevital) _________ the seizure threshold
Lowers
What drug is know for histamine release?
Sodium thiopental (pentothal)
What are the 3 MOAs of barbiturates?
-Potentiate GABA
-Block glutamate @ AMPA receptors
-Block neuronal Nicotinic receptors
Primary anesthetic use of midazolam (versed) is __________
premedication
An induction dose of midazolam (versed) would ________ emergence
Delay emergence
Midazolam (versed) causes _________ amnesia
Anterograde
_________ increase GABAa affinity for GABA
*only one in Dr. B PP that specifies this
benzos
Which subunit of the GABAa receptor do benzos bind to to mediate sedative, amnestic & anticonvulsant effects
a1 subunits
Which subunit of the GABAa receptor do benzos bind to to mediate anxiolysis, anti-hyperalgesia, & centrally mediated muscle relaxation
a2 subunits
Onset of diazepam (valium) IV
Almost immediate
Onset of midazolam (versed) IV
1-5 min
DOA of diazepam (valium)
20-30min
DOA of midazolam (versed)
2 hrs
T 1/2 of diazepam (valium)
30-50 hrs
*“half-life is equal to pt age in years”
T 1/2 of midazolam (versed)
1-4 hrs
Metabolite of midazolam (versed)
1-hydroxymidazolam
Metabolism of diazepam (valium)
Desmethylmedazolam
to
Nordiazepam
to
Oxazepam (active benzo) –> secondary peak 6-12hrs
to
Inactive metabolite
Diazepam (valium) interacts (C/I) w/ ___________ & ___________
-erythromycin
-anti-fungals
Midazolam (versed) C/I w/ _________ & __________
-pregnancy
-elderly (all benzos)
(t/f) benzos are ok for neuro cases
True
Benzos _______ the seizure threshold
increase
(t/f) benzos do not decrease central respiratory system
False
*midazolam decreases central respiratory system the most
What drug reverses benzos
Flumazenil (Romazicon)
Is flumazenil (romazicon) a competitive or non-competitive antagonist to benzos
Competitive
Flumazenil (romazicon) is chemically similar to benzos except that the phenyl group
is replaced by a _________ group
carboxyl
(t/f) DOA of Versed exceeds Romazicon
True
*VERNON PP SAYS ONLY LORAZEPAM IS LONGER THAN FLUMAZENIL
*DR. B SAYS VERSED
*EXPECT NEED FOR RE-DOSING!!
Flumazenil (romazicon) is C/I in pt w/ ________ disorders
Seizure disorders
________ is the cardiac stable induction agent
Etomidate
You give midazolam (versed) to pt in pre-op and you want to run to the restroom real quick before you take the patient to the OR. It will only take a minute. Is this ok?
*BLUE BOX
NO
*DO NOT LEAVE PT UNATENDED AFTER VERSED ADMINISTRATION
Etomidate causes _________ ___________ r/t to the suppression of cortisol production due to suppression of a the synthesizing enzyme _____-______________ in the adrenal ________
-Adrenal suppression
-11β-Hydroxylase
-adrenal cortex
(t/f) etomidate can cause burst suppression
True
(t/f) Etomidate produces just as much respiratory depression as other IV anesthetic agents
False
*less than other agents
T 1/2 of flumazenil (romazicon)
Dr. B = 41-79 min (t 1/2)
Dr. V = 45-90 (DOA)
*SHORTER/LONGER THAN VERSED AND/OR LORAZEPAM –> MAY HAVE TO REDOSE!!
Regarding flumazenil (romazicon), if you have to give > ____mg dose to reverse the pt, then there is an underlying issue
> 0.6mg
Midazolam has a _____ ring as its primary structure which makes is H2O soluble and prevents pain on IV injection d/t not having to use preservatives/solvents
Imidazole ring
*iMIDAZOLe = MIDAZOLam
_________ ___________ of benzos can prolong duration of benzos in renal failure pts
Active metabolites
Etomidate MOA
Dr. B - mimics inhibitory effects of GABA
Dr. Vernon - allosterically binds GABAa & increases affinity for GABA
(t/f) high doses of etomidate, >0.3 mg/kg, can cause decreases in BP & CO
True
(even though its considered cardiac stable)
Of all of the clinically used IV anesthetics, __________ has the greatest selectivity for GABAA Receptors and has the fewest relevant interactions with other ion channels/receptors.
*BLUE BOX
Etomidate (amidate)
The excitatory phenomenon (myoclonus) caused by etomidate can be mitigated by concurent administration of _________ or __________
Opoids or Benzos
Etomidate is a potent cerebral ______________
vasoconstrictor
Etomidate is not approved for children <____ yrs
Dr. B - <10 yrs
Dr. V - <5 yrs
(t/f) etomidate is structurally similar to some other anesthetics
False
*structurally unrelated to other anesthetics
Preservative in Diprivan
EDTA
Preservatives in Propofol
-sodium metabisulfite (bronchoconstriction in Asthma)
-benzyl alcohol
Propofol MOA
Dr. B - GABA mimetic (direct)
Dr. V - Allosterically binds GABAa & increases affinity for GABA
Other sources: (hold no weight on this test)
Low dose = allosteric
High dose = direct
Propofol predominantly binds to the ____ subunits of the GABAa receptors
B2 subunits
Are there amnestic properties in propofol?
Dr. B - No
Dr. V - Yes
Other sources: ???
Egg allergies are C/I w/ propofol
Technically no
Egg lecithin/yolk allergies are C/I w/ propofol
Yes
The contents of an opened ampule, vial or syringe must be discarded if not used within ___ hours.
*BLUE BOX
6 hrs
When preparing a syringe, label appropriately with initials, date and _______
*BLUE BOX
time of expiration
Propofol with ____________ preservative increases bronchial tone and does not blunt the _________ mediated effects leading to _____________.
-metabisulfite
-vagally
-bronchoconstriction
Sodium metabisulfite – can potentially irritate __________ and/or those allergic to _______ drugs
-asthmatics
-sulfa
Mixing lido & propofol: No more than ___mg of Lidocaine with ___mL of Propofol
Starts to separate after ___ hour
Risk of _________ _________ ________
*BLUE BOX
-20mg Lido w/ 20mL prop
-1 hr
-microscopic fat emboli
Propofol is a cerebral _____________
vasoconstrictor
*this is how it decreases ICP
Primary disatvantage of propofol
Depressive effects on CV effects
Caution w/ propofol in pts with critical ______ ________ or __________ ________
-aortic stenosis
-cardiac tamponade
Which is faster onset & offset. Ketamine or propofol
Ketamine (per Dr. B)
Which med can cause centrally mediated muscle relaxation?
Benzos
Elderly have ________ volume in their central compartment so you would ________ propofol dose
Decreased
Decreased
Peds have ________ volume in their central compartment so you would ________ propofol dose
Increased
Increased
If you don’t have methohexital (brevital) then you can give ___________
etomidate
Onset of Propofol
9-51 sec (average 30 sec)
DOA of propofol
3-10 min
Induction dose of propofol
1-2.5 mg/kg
Pt w/ high risk PONV & MH. What induction agent should you use?
Propofol
Symptoms of propofol infusion syndrome
-Hypertriglyceridemia
-Metabolic acidosis
-Rhabdomyolysis
-Renal failure
-Hemodynamic instability
Propofol infusion syndrome is associated with high dose infusions for > ___ hours
48 hrs
The Dissociative Anesthetic
Ketamine
Why does ketamine cause dissociation?
Depresses the medial thalamic nuclei & blocks the association between the thalamus and the cerebral cortex
Ketamine depresses the ________ _________ __________ & blocks the association between the ________ and the cerebral cortex
-medial thalamic nuclei
-thalamus
Ketamine is derived from _______
PCP
(t/f) Ketamine has minimal effects on respiratory drive and airway reflexes
True
Using ________ can decrease the emergence delirium caused by ketamine by ___%
-benzos
-50%
Ketamine MOA
NMDA Receptor antagonist in the spinal cord and brain
*Selective depression of the medial thalamic nuclei
Ketamine causes increased __________ which can lead to ____________ (emergent scenario)
-salivation
-laryngospasm
Metabolite of ketamine
Norketamine
Norketamine is ____ -____ as potent as ketamine
- 1/3rd - 1/5th
Onset of ketamine
1-2 min
DOA of ketamine
5-15 min
Ketamine stimulates endogenous _________ release
catecholamine
Ketamine induction dose
1-2 mg/kg
GABA stands for __________
Gamma-aminobutyric acid
Ketamine is the only true _____________ (think airway)
-bronchodilator
Hypovolemic pts can benefit from what induction agent especially
Ketamine
What induction agent has relatively low protein binding when compared to other agents
Ketamine
What drug commonly causes a cataeleptic state
Ketamine
You see ur pt w/ eyes open, pupils reactive to light, corneal reflexes intact, lacrimation, blinking, involuntary muscle movement. You induced w/ ketamine. Is this ok?
Yes
Normal cataeleptic state caused by ketamine
List some big C/I co-morbidities w/ ketamine administration
-CHF
-CAD
-uncontrolled HTN
-neuro and cererbral aneurysms
Dexmetomidine ratio of α2:α1 = _____:__
1620:1
Dexmedetomidine MOA causes analgesic effects at the spinal cord and a supraspinal site called the __________ ___________
Locus Ceruoleus
Name the 3 main MOAs of dexmedetomidine
-a2 agonist
-hyperpolarization of neurons via K+ efflux
-Inhibits adenyl cyclase
(decreases cAMP)
Dexmedetomidine typically decreases HR & BP, however initially direct effects on peripheral
α2 receptors can predominate
leading to __________ BP
Increased BP
Dexmedetomidine can cause significant hypotension in patients with increased sympathetic tone such as __________, ___________ and ____________
Diabetics
Hypovolemics
Elderly
Neuro wise, dexmedetomidine only decreases _______
CBF
Dexmedetomidine onset
5-10 min
Dexmedetomidine DOA
60-120 min
Dexmedetomidine Infusions should not exceed ___ hours
24 hrs
Loading dose of dexmedetomidine
0.5-1 mcg/kg over 10 min
Respiratory effects of dexmedetomidine
Preserved - possible small to moderate decrease in TV
Decreased salivation
Main cardiac effects of dexmedetomidine
Bradycardia
Hypotension
Dexmedetomidine can be used to tx __________
Shivering