Inhalants Flashcards
Name the organic inhalants
Iso, sevo, des
What kind of inhalant are iso, sevo and des
Organic ethers
What kind of inh is halothane
Organic aliphatic hydrocarbon
What kind in inh is NO
Inorganic
Define halogenation
Adding Cl, Br or F
What does halogenation do
Decreases reactivity, increases potency, makes non-flammable
Is toxicity still possible with halogenation
Yes- esp with F
What effects do Br and Cl have on inh’s
Increases potency
Which halogens increase potency
Br and Cl
What effect does F have
Improves stability (less decomp) but reduces potency and solubility
Halo vs iso
halo requires preservative and can cause dysrhythmias but is more potent
What preservative is used in halo
Thymol
What inh properties determine administration
Vapor pressure, BP, density/SG
What properties determine how inh travel in body
Solubility and blood gas partition co-efficient
What can change the physical state of matter of inh
motion and degree of intramolecular attraction
Define inh gas
Exist in this form at room temp and atmospheric pressure
Which inh is a gas
NO
Define inh vapor
Exists as liquid at room temp/atmos. pressure
Which inh is a vapor
Iso, sevo, des
T/F Vapors and gases have same physical properties
Yes- still follow gas laws
Define partial pressure
Pressure a gas exerts on walls of closed container
Define dalton’s law
Total pressure of a gas mix equals the sum of all of their partial pressures
3 ways to quantify inh’s
Pressure (mmHg), **Concentration (%), mass (g or mg)
Does concentration change? Does partial pressure change?
Conc changes relative to whole gas mixture or to atmospheric pressure; partial pressure is absolute value
Describe changes in vol%
Vol % changes in response to atmospheric pressure and may be different in different body compartments
Define vapor pressure
Pressure molecules exert when liquid and vapor phases are in equilibrium
Define saturated vapor pressure
Max concentration of molecules in vapor state for a liquid at a certain temp
Gas vs vapor differences in administration amounts
Gas administered from a % concentration, vapor is delivered as a max concentration that depends on saturated vapor pressure
As temp decreases, vapor pressure ________
decreases
Why does vapor pressure decrease with temp-
Cooling (rather than evap) decreases delivered vapor concentration due to decreased vapor pressure
Define BP
Temp where vapor pressure = atmos temp
BP decreases as altitude _________
Increases
What is the BP of des
Close to room temp
Rank inh’s by BP low to high
Des
Which inh has the highest vapor pressure
Des
Iso in sevo vaporizer - what happens
Iso vapor pressure 238 is greater than sevo 157, overdose likely due to more iso being delivered
Inh vapor pressures (actual and rank low to high)
Iso- 238; Sevo- 157; des- 669; halo- 243;
Sevo
Def inh solubility, how is it expressed
Total number of gas molecules dissolved into a solvent- Blood: gas partition coefficient
What factors influence solubility (3)
Molecular weight of gas, chem nature of solvent, partial pressure gradient between gas and solvent
Does solubility change with temp?
Yes
Partition coefficient of 2% blood and 1% gas
2.0 (blood:gas)
Partition coefficient of 1% blood and 2% gas
0.5 (blood:gas)
What does partition coefficient predict
Speed of induction, recovery, change in depth
_______ (lower/higher) B:G PC = faster onset and recovery
Lower
The majority of modern inhs are
halogenated organic vapors
What determines how many molecules of inhalant are available to produce anesthesia
Vapor pressure
What determines max concentration of inhalant that can be delievered
Saturated vapor pressure