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Flashcards in Anesthetics Deck (19):
1

IV anesthetics
kinetics
hypnosis/amnesia
analgesia (cat for ket, myo for eto)

thiopental, propofol, etomidate, ketamine
FAST (onset & offset)
yes, except ketamine produces "dissociative" amnesia

none for pro/etom; the may have enhanced response; really only for ketamine

no effect for thio/propo; myoclonus for etomidate; catalepsy for ketamine

2

MOA of IV anesthetics

thio/propo/eto --> enhace GABAa receptor fxn --> hypnosis, amnesia

ketamine blocks NMDA --> analgesia

3

thiopental chars

fast onset, short duration (IV)
mainly used for induction, but not maintenance b/c high fat storage

*IV agents mainly all used for induction, not main

efx: cardioresp depression; cerebral protection; decr in CMRO2 and CBF (brain using less O2) good for incr ICP b/c decr brain volume

*ALL anesthetics are lipid soluble --> fast redistributions --> blood levels go down fast and you wake up quick

4

propofol chars
upside compared to thiopental?
downside?

fast onset/short duration/rapid elim

induction and maintenance, and for CONSCIOUS sedation

CR depression/Cereb protection

less NV (antiemetic)
pain on injection

*#1 drug used for IV

5

etomidate
3 SE's?

fast onset/short dur/semi-rapid elim
used for induction

MINIMAL CR depression (GOOD for pts who you don't want to decr BP much); cereb protection

myoclonus/adrenal suppression (w/prolonged admin)/pain on injection

6

ketamine

fast onset/longer dur/semi-rapid elim
IV/IM induction of anesthesia/analgesia

CV STIMULANT (activates SNS)
maintains spontaneous ventilation; bronchodilator
NO celeb protection (incr CMRO2 and CBF) --> DON'T GIVE TO PT w/high ICP

dissoc anesthesia; catalepsy; incr secretions
analgesic
postop dysphoria (hallucinations for days after: one reason not to give to older pts)

7

inhaled anesthetics
onset/offset
hypnosis/amnesia
analgesia
relaxation

isoflurane, sevoflurance, desflurane, N2O

all fast (N2O=Desflurane> sevoflurane> isoflurane); but slower kinetics than IV drugs

less fast ones have HIGHER blood solubility

good for kids, producing hypnosis/amnesia

N2O less good for hypnosis/amnesia bc EC50 is above ATM pressure; best for analgesia
*can use for skittish pts when placing an IV so it doesn't hurt as much

all the same for relaxation

8

inhaled anesthetic MOA?

volatile: enhance GABAa receptor fxn --> hypnosis/amnesia; Na/Ca/K --> analgesia, skel musc relaxation

N2O blocks NMDA's --> analgesia; not as great for amnesia

9

volatile anesthetics

onset/offset depd on uptake/solubility; little metal, pulm elim
used for induction/maint (after IV induction)

CV depresion; resp depr (rapid shallow breaths); can incr ICP (decr CMRO2 but incr CBF due to vasodilation)

"complete anesthetics"
bronchodilators=impaired mucociliary clearance
airway irritation: des>iso>sevo
des=desgusting

10

malignant hyperthermia
tx? also worry about 3 other things?

rxn only w/VOLATILE anesthetics
due to pts having mutations to proteins inv in skeletal musc excitation-contraction coupling --> incr myoplasmic Ca

hypermetabolism --> RIGIDITY, HEAT, CO2 production, ACIDOSIS, RHABDO, HYPERkalemia

Rx: DC volatile anesthetic; give IV DANTROLENE; then treat acidosis and alkalinize urine to tx the myoglobinuria as well as hyperkalemia

11

local anesthetics

analgesia
local admin near peripheral nerves --> sensory/motor/sympathetic block

not specific for pain fibers, so they block AP's in ALL axons

they target the VGSC (thus AP's don't reach CNS from PNS)

takes time bc needs to cross cell membrane in order to bind the INNER side of the VGSC pore

12

esters v amides local anesthetics

problem w/esters?

esters: plasma esterases
amides: metabolized in liver

esters turn into PABA --> allergy/anaphylaxis

*know it's an ester if it only contains ONE i in the name

13

local anesthetic use

amides: lido/mepi/bupi/ropi/EMLA
(lido only for topical; all else for sub Q, PN, Neuraxial)

esters: benzocaine/tetracaine/cocaine
*all primarily for topical (exc tetracaine also for neuraxial)

14

fast onset short duration local?

longer dur?

lidocaine

bupivicaine/ropivacaine for longer dur

EMLA=lido+prilocaine --> hoped to penetrate keratinized skin (but takes like an hour)

15

local anesthetic toxicity
2 drugs that cause MHb?

systemic: absorption; accidental intravascular injection (very high blood levels rapidly)

METHEMOGLOBINEMIA: prilocaine and benzocaine

16

systemic toxicity of lidocaine

1st: CNS efx: tingling/NV/tremors/confusion

then: seizure, coma

finally: resp/cardiac arrest

unique: BUPIVICAINE can cause cardiac arrest before you see any CNS excitation

17

how to avoid systemic toxicity?

1) safe doses:
lidocaine: decr blood flow and thus absorption --> longer anesthetic effect bc still sitting by the nerve but not absorbed

3) avoid intravascular injection: ASPIRATE before injection; give slowly in incremental doses

18

tx systemic toxicity

1) supportive: airway/BZD's for seizure/ACLS for arrhythmias and CV collapse

2) lipid emulsion: 1.5 mL/kg bolus

19

methemoglobinemia
2 drugs that cause?
tx?

prilocaine/benzocaine
high levels oxidize Fe2-->Fe3 which then can't carry O2

tx: METHYLENE BLUE (1-2mg/kg)