Isoflurane Flashcards
When and by whom was Iso synthesized?
1965, Ross Terrell and Louise Speers Ohio Medical
When was Iso approved and most widely used in US?
1981, on hold for causing cancer in mice but not true.
What 6 things are general requirements for patient use of gases?
Volatility (evaporate at normal temp, = 4 carbon atoms); Nonflammability (limited H atoms, substituted with Cl or F aka halogenation); Low boiling point, Stable in soda lime, Easy to manufacture at lower cost (Cl atom makes it more cost effective); low biodegradation/metabolism.
Isoflurane is a structural isomer of which other gas?
Enflurane
What is the long name of Isoflurane
1-chloro-2,2,2-trifluoroethyl, difluoromethyl ehter
What is the molecular weight of isoflurane?
184.5g
What are the characteristics of isoflurane?
clear, colorless, stable liquid, no additives or stabilizers, pungent odor (resp irritant)
Isoflurane is similar in chemical structure to which other gas?
Desflurane, only difference in des is F atom for Cl atom. Des is chemically more stable (0.02%) vs Iso (0.2%) but not clinically significant.
True/False: Isoflurane is not altered by CO2 absorbents, light, or moisture.
True, also non-reactive with metal and stored in amber bottles.
Where is isoflurane metabolized/biotransformed and a high or low level of metabolism?
Eliminated mostly unchanged through the lungs, very low metabolism <0.2%, oxidative metabolism by cytochrome P450 in liver, increases trifluoroacetic acid (small rise in serum F levels)
What is the B:G solubility coefficient of Isoflurane? Is that high or low?
1.46, high. 1.46x higher in blood to every 1 molecule in alveoli. prefers to be in blood state.
What does oil:gas partition coefficient reflect? What is isoflurane’s? Is that high or low?
measure of potency; 91; HIGH.
What is the MAC of Isoflurane? high or low potency?
MAC 1.2; high
Is induction fast or slow with isoflurane?
slow, high b:g; usual onset 5-7 min
Is emergence fast or slow with isoflurane?
slow if prolonged exposure as it is highly soluble in fat, muscle, and the brain.
Does high cardiac output affect isoflurane induction?
Yes, highly soluble in blood so it slows the concentration in the lungs and alveolar partial pressure leading to lower concentration in brain.
What cardiac effects does Isoflurane have?
CO maintained, HR increase 10-30bpm, slight SV reduction, decreased SVR, dysrhythmias can occur if rapid increases in MAC, coronary steal: dilates coronary arteries, theoretically diverts blood from stenotic arteries.
What respiratory effects does isoflurane have?
bronchospasm/irritation to upper resp mucosa, bronchodilation of bronchial smooth muscle, most respiratory depressant of all volatiles–related to anesthetic depth(decreased Tv, RR increase), blunts normal response to hypoxia and hypercapnia (central and peripheral chemoreceptors)
What cerebral effects does isoflurane have?
reduces CMRO2 requirements, decreased CVR >1 MAC, increased CBF and ICP but can be reversed with hyperventiation, suppresses seizure activity, 2 MAC=electrical silent EEG.
What are the neuromuscular effects of isoflurane?
muscle relaxant effect progresses with depth, potentiates non-depolarizing relaxants, uninhibited spinal cord reflexes–shivering.
What are the renal effects of isoflurane?
decreased renal blood flow, GFR, and UOP
What are the hepatic effects of isoflurane?
reduced total hepatic blood flow, maintains hepatic oxygen supply, minimally affects liver function test, low metabolism toxicity effects.
What are the GI effects of isoflurane?
PONV, more with long cases, PO ileus.
Can you do inhalation induction with isoflurane?
NO, pungent
