Inhaled Anesthetics Flashcards
classification of desflurane
fully fluorinated methyl ethyl ether
metabolism of desflurane
0.0-0.02 % undergoes metabolism
low solubility- like Nitrous Oxide- undergoes very little metabolism
MAC for desflurane
6.6%
Blood/Gas Particion Coef for Desflurane
0.42
Vapor Pressure of Desflurane
669
Boiling Point of Desflurane
22.8
Cardiovascular Effects of Desflurane
abrupt increases = sympathetic stimulation
increased HR and BP
in general = decreased BP and HR no change in CO, increased RAP, decreased SVR, no change in PVR
Pulmonary effects of Des
dose-dependent increase in RR decreased Vt decreased ventilatory response to PaCO2 and hypoxemia above 1 MAC = airway irritation bronchoconstriction ** SMOKERS increased secretions coughing breath holding laryngospasm
Neuro effects of Des
no retrograde amnesia
decreased CMRO2
increased CBF
increased cerebral vasodilation
hepatic effects of des
oxidatively metabolized by CYP45-
forms acetylated liver protein
can evoke antibody repines and hepatotoxicity
NOT common b/d minimal metabolism
renal effects of des
dose-related decreases in renal blood flow
& GFR
&UOP
decrease in BP and CO
misc. effects of des
dose-dependent enhancement of the effects of NMBAs
decrease uterine smooth msucle contractility & blood flow
EXCEPT N2O
what properties of desflurane require the Tec 6 vaporizer and what does it do?
Desflurane’s high vapor pressure- 669
and boiling point near room temp 22.8C
require Desflurane to be heated to 23-25C
and pressurized to 1500 mmHg to achieve predictable concentrations of delivered Des
blood: brain of des
1.3
muscle: blood of des
2
fat: blood of des
27.2
classification of isoflurane
halogenated methyl ethyl ether
metabolism of iso
0.0-0.2% hepatic metabolism
oxidative metabolism by CYP450 to form difluoronmethanol & trifluoroacetic acid
antibody formation - hepatotoxicity
MAC of iso
1.2%
BGPC of Iso
1.46
Vapor Pressure of iso
240
boiling point of iso
48.5C
brain:blood of iso
1.6
muscle:blood of iso
2.9
fat:blood of iso
44.9
oil:gas iso
98
contraindications with Iso
Prolongation of the QTc
CV effects of iso
QTc prolongation coronary vasodilation- cardioprotective dose-dep decrease in reflex of sympathetic flow decrease BP increase Hr minimal CO change increase RAP decrease SVR no change in PVR
which agent is the most cardioprotective?
Iso- even though it has prolonged QTc
which agent is the most potent vasodilator
isoflurane
reps effects iso
dose sep increase in RR
decrease in Vt
decrease in ventilation response to increase Pa Co2 and hyperemia
bronchodilation
neuro effects of iso
NO retrograde amnesia decrased CMRO2 incrase CBF cerebral vasodilation decreases resistance to reabsorption
which agent is the most cerebral protection?
iso
hepatic effects of iso
vasodilator of hepatic circulation
CYP450 metabolism- hepatotoxicity risk
renal effects of iso
dose-dep decrase in RBF,
&GFR
&UOP
d/t decreased BP and CO
which agent costs more, iso, des, sevo
sevo>des> iso
classification of sevoflurane
halogenated methyl isopropyl ether
metabolism of sevo
5-8% of sevo is metabolized
oxidative metabolism
trifluoroacetic acid is NOT formed thus NOT hepatotoxic
Blood:Gas PC of sevo
0.69
MAC of sevo
1.8-2
Sevo Vapor Pressure
160-170
Boiling Point of sevo
58.5 C
brain:blood sevo
1.7
muscle:blood sevo
3.1
fat:blood sevo
47.5
oil:gas sevo
55
contraindications with sevo
compound A formation- renal damage
QTc prolongation
agitation 7-15%
CV affects of sevo
coronary vasodilation RARE cardioprotective decreased temp- all cutaneous vasoconstriction decreased: BP and CO increased: HR decreased RAP decreased SVR no change in PVR
reps effects of sevo
dose-dep increase in RR decrease in Vt decrease vent response to CO2 & hypoxemia- ALL POTENT bronchodilator NON-PUNGENT!
which inhaled anesthetic causes the least degree of airway irritation
sevo
neuro effects of sevo
no retrograde amnesia
decreased CMRO2
increased CBF
increased cerebral vasodilation
renal effects of sevo
all dose related decrease in renal blood flow
&GFR
& UOP
d/t decreased BP and CO
misc effects of volatiles
Volatile Anesthetics produce dose-dependent enhancement of the effects of NMBAs (ethers>halothane). •
Obstetrical- Volatile Anesthetics produce similar dose-dependent decreases in uterine smooth muscle contractility & blood flow (except ).
how do we protect against production of compound A with sevo
At increased temperatures, desiccated CO2 absorbent may degrade Sevoflurane to produce Compound A (trifluoromethyl vinyl ether) which is nephrotoxic & hepatotoxic in animals.
Fresh gas flows of 2 L/min are recommended to decrease the production of Compound A.
Flows of 1L/min may be used for up to 2 MAC-hours.
Flows below 1L/min are not recommended.
which agent is the least likely to form Carbon Monoxide when reacting with the CO2 absorbent?
sevo
MAC of enflurane
1.6%
BGPC of enflurane
1.9
Vapor pressure of enflurane
172
BP of enflurane
56.5
metabolism of enflurane
0-3%
CYP450 oxidative metabolism to form organic and inorganic fluoride compounds and possibly neoantigens in susceptible patients
contraindications with Enflurane
QTc prolongation
EEG activity- seizure like tonic-clonic twitching! MAC >2
trifluroacetic acid- hapatotoxic but less than halothane
CV effects of enflurane
decrease BP no change in HR decrease CO decrease SVR no change in PVR
hepatic effects of enfluane
ALT is increased after enflurane admin
classification of halothane
halogenated alkane
MAC of halothane
0.75%
blood:gas PC halothane
2.54
Vapor Pressure halothane
244
Boiling Point halothane
50.2 C
metabolism of halothane
15-40% metabolized by the liver
- Halothane undergoes oxidative metabolism by CYP-450 enzymes when ample oxygen is present.
- Halothane undergoes reductive metabolism by CYP-450 enzymes when oxygen is reduced.
- metabolites: trifluoroacetic acid, chloride, & bromide
- triflouroacetic acid may stimulate formation of antibodies against hepatic microsomal proteins
