Inhalational agents - Uptake and Distribution Flashcards
Process of getting the anesthetic agent from the anesthetic machine to the patient’s CNS (5)
Vaporizer
Circuit
Alveoli
Blood / arterial
Brain (CNS)
Series of ___ ___ ___to move agent through barriers to the CNS
partial pressure gradients
Series of partial pressure gradients:
PA —— Pa ——- Pbr
Partial pressure of anesthetic vapor ___ every step.
[Uptake and distribution]
decreases
Partial pressure between alveolar, and ___equilibrates quickly
[Uptake and distribution]
arterial
___ ___ ___equilibrates rapidly with that in the brain.
[Uptake and distribution]
Arterial partial pressure
We know that ___ ___ don’t produce unconsciousness directly
[Uptake and distribution]
alveolar concentrations
However, alveolar concentration is a great estimate of ___/___ ___ which we can not directly measure
[Uptake and distribution]
CNS/brain concentrations
Thus, we use alveolar concentration as a “___ for CNS/brain concentration.
[Uptake and distribution]
stand-in”
FGF (fresh gas flow) is determined by the ___ and ___ settings.
vaporizer, flowmeter
FI (Inspired gas concentration) is determined by 1. ___ 2. ___ 3. ____
FGF rate, breathing-circuit volume and circuit absorption
FA (alveolar gas concentration) is determined by 1. uptake (=(lambda)b/g x C (A-V)xQ 2. ___ and 3. the concentration effect and second gas effect
Ventilation
Uptake equation:
=(lambda)b/g x C (A-V)xQ
The concentration effect and second gas effect:
a. concentrating effect b) augmented inflow effect
Fa (arterial gas concentration) is affected by ___/___mismatching
ventilation/perfusion
Inhalation anesthetic agents must pass through many barriers between the ___ ___ and the brain.
anesthesia machine
The vapor pressure of isoflurane is ___ (33% of atmospheric pressure).
242 mm Hg
The MAC of isoflurane:
1.17%
The vaporizer of isoflurane is dialed to deliver about ___
2%
The concentration must be diluted out; that starts in the ___.
vaporizer
In the circuit, there is the ___ ___and the ___ that is being rebreathed
fresh flow, gas
This dilutes out the ___ ___ more.
inspired agent