Inhalation Anesthesia #1 Flashcards
2 true gases used in anesthesia
Nitrous and Oxygen
Other inhaled agents, besides O2 and N2O are known as
Lipids, Vapors, or Volatile Liquids
All gases are __________
non ionized and have low molecular weight and delivered to the blood via the lungs
The goal of inhalation anesthesia is to produce the anesthetic state by creating a specific concentration (MAC) of anesthesia molecules in the __________. This si done by establishing a _________ of an agent in the lungs, which then equilibrates with the brain and spinal cord.
central nervous system
partial pressure
FI (inspired gas concentration) is determined by
FGF rate
breathing circuit volume
circuit absorption
At equilibrium, CNS partial pressure will = _____, which will = ______
CNS partial pressure= blood partial pressure = alveolar partial pressure
Palveoli=Pblood=PCNS
FA/FI ratio is the
degree to which the alveolar concentration of an anesthetic becomes closer to the inspired concentration of an anesthetic, expressed as a ratio
The rate at which the alveolar concentration of anesthetic equals the inspired concentration of anesthetic
Three factors that affect FA/FI ratio
minute ventilation
blood:gas partition coefficient
cardiac output
Cardiac output has a ______ relationship with speed of induction
inverse
Sevo is _____% metabolized
Iso is _____% metabolized
Des is _____% metabolized
Sevo is 2 % metabolized
Iso is 0.2 % metabolized
Des is 0.02 % metabolized
FA (alveolar gas concentration) is determined by
uptake
ventilation
the concentration effect and augmented inflow effect
Fa (arterial gas concentration) is determined by
ventilation/perfusion mismatching
The concentration effect is
administration of 2-3 times desired concentration of a gas until the desired depth of anesthesia is reached
second gas law/ augmented inflow effect is
the simultaneous administration of a “slow” agent with a “fast” agent, theoretically can speed the onset of the slower agent
(theoretical concept, clinically insignificant)
The ventilation effect is
the faster and more deeply a patient breathes or is ventilated the faster a patient loses consciousness at the start of the anesthetic.
Inhalation anesthetics move down a concentration gradient
Normally, alveolar and arterial anesthetic partial pressures are assumed to ______
equalize
Fa is consistently less than end-expiratory gas would indicate __________. This may be due to _____, _______, _______.
ventilation/perfusion mismatch
due to venous admixture
alveolar dead space
non-uniform alveolar gas distribution
In a right to left cardiac shunt, there is a ______ anesthetic need.
Increased
In a left to right cardiac shunt, there is a ______ anesthetic need.
decreased
Oil/gas solubility is a indicator of
potency and lipid solubility
the higher the oil/gas solubility, the higher the potency and the higher the lipophilicity
The Meyer-Overton correlation states that the
potency of an anesthetic can be predicted from its liposolubility
The blood/gas partition coefficient is an indicator of
how fast the onset is. The lower the number the faster the onset.
The pressure exerted by the molecular collisions of the gas against the container walls is known as
Vapor Pressure
As long as liquid remains in a container, the vapor pressure is ________ of the volume of the liquid
independent
Vapor pressure is proportional to
temperature
For any mixture of gases in a closed container, each gas exerts a pressure proportional to its fractional mass; this is known as
Partial Pressure
The sum of the partial pressures of each gas in a mixture of gases equals the total pressure of the entire mixture, this is known as
Daltons Law
Term used to describe the tendency of a gas to equilibrate with a solution, hence determining its concentration within the solution
Solubility
The relationship of concentration of a gas in solution to the partial pressure of the gas with which the solution is in equilibrium
Henry’s Law
In the gas phase, fractional concentration (% by volume) is equal to the
partial pressure divided by ambient pressure
The _________ is used for any gas in equilibrium with a liquid, a certain volume of that gas dissolves in a given volume of liquid
solubility coefficient
The concentration of each gas in a mixture of gases in solution depends on two factors:
partial pressure in gas phase in equilibrium with the solution
Its solubility within that solution
Anesthetic gases diffuse from the lungs into the blood until the partial pressures in the _____ and _____ are equal
alveoli and blood
Concentrations of anesthetic in the blood depends on the _______ and the _______.
partial pressure of the gas at equilibrium
blood solubility
The _________ of a gas in a solution represents the pressure that the gas in equilibrium with the liquid would have if a gas phase existed in contact with the liquid phase.
partial pressure
The concentration of anesthetic in target tissue (brain) depends on the ______ and _______
partial pressure at equilibrium
target tissue solubility
Monitoring the alveolar concentration of exhaled anesthetic provides an index of their ________
effect in the brain
Inhaled anesthetics equilibrate based on their _________ in each tissue, not based on their concentrations
partial pressures
Three factors that influence the uptake of volatile anesthetic:
Alveolar blood flow
Blood: gas solubility
partial pressure gradient between the alveoli and the venous blood
