Uptake/Distribution of INH agents Flashcards
Uptake of the volatile anesthetic into the blood is determined by what 3 things?
Solubility of the agent
CO
A-v pressure differences
________ determines how the anesthetic will partition itself b/t the blood and air phases when equilibrium is reached.
Solubility
Solubility looks at the equilibrium state of equal __________________
partial pressures
Solubility is expressed in terms of ___________ ___________
partition coefficients
What is the B:G coefficient for Desflurane?
.42
What is the B:G coefficient for N2O
.47
What is the B:G coefficient for Sevo?
.69
What is the B:G coefficient for Isoflurane?
1.4 (intermediate)
What is the B:G coefficient for Enflurane?
1.8
What is the B:G coefficient for Halothane?
2.4 (most soluble)
Solubility will determine the ______________
alveolar concentration
A lower HCT will make the gas _______ soluble which will mean a ______ induction
less soluble
faster
The steeper the FA/FI slope, the __________ the onset of the agent.
faster
T/F: PA = Pa = Pbr
true! this is how we use PA to estimate the depth of anesthesia and MAC
The PA (pressure in alveoli) of volatile anesthetic is determined by what 4 things:
PI (inhaled partial pressure)
alveolar ventilation
breathing circuit
FRC
Changes in alveolar concentration are more rapid with a _____ rate and _____ tidal volumes
fast
small
IE) hyperventilate for a more rapid change
The ________ soluble agents have fastest rate of the alveolar gas matching the inspired concentration over time
least
The First knee of the FA/ FI ratio is the uptake by the ____________________ and the 2nd knee represents uptake by the ________________
VRG
MG
The higher the solubility, the ________ the increase in alveolar concentration rise toward inspired concentration.
slower.
The use of high delivered concentrations is called “________________”. We use this with soluble agents to get a ________ induction.
overpressure
faster – like with Halothane
The Lower the B/G solubility coefficient, the _________ time emergence will take
shorter
If you increase the CO the FA/FI curve will
decrease
The a-v difference reflects uptake of anesthetic by the _________
tissues
For lean tissue (brain).. tissue/ blood partition coefficients are __________
between 1-2
For Fat, tissue/blood partition coefficients are __________ except for N2O which is _____.
very high (27-67) 2.3
At the VRG, equilibrium is reached within ___-___ minutes
5-15
The VRG makes up ____% of our body mass but ____ % of our CO.
10
75
Definition of MAC is:
Minimum Alveolar Concentration
MAC is the concentration that will……
produce absence of movement in 50% to a noxious stimuli
Increasing ventilation will increase the FA/FI curve more for a ___________ soluble agent.
highly
In a SPONTANEOUSLY ventilating pt, at % inspired increases, the FA/FI ratio ________
decreases (protective negative feedback mechanism against OD)
The higher the FRC, the ___________ the speed of induction
slower
The greater the alveolar ventilation/FRC ratio means the ___________ the induction
faster
With a V:Q abnormality, you will get a L to R shunt and this causes a ____________ effect that will cause a _______ induction.
dilutional
slower
The ________ the solubility of the agent, the more shunting you will see.
lower
_____________ happens when a large volume of gas is absorbed and the remaining residual gas in the lung is concentrated as volume decreases
concentration effect
The 2nd gas effect happens with the use of what gas?
N2O
______ soluble anesthetics washout first
less
Which is more soluble? N20 or nitrogen?
N20
What is the B/G coefficient of Nitrogen vs N20?
N2O=.47, nitrogen = .014
__________ hypoxia is possible with the use of N2o
diffusion
