Quiz 2- Inhalants Flashcards
Is the recovery better with inhalants or injectables
Injectables
Why do we use inhalants
It uses the lungs to distribute and eliminate so you don’t have to rely on (and worry about) renal and hepatic metabolism. You can also precisely adjust anesthetic depth and have good control
Why don’t we always use inhalants
The equipment is expensive and bulky and the induction process without injectables may be difficult
What is our best idea on how inhalants work
The vapors use the partial pressure gradient of the lungs (moves from high to low equilibrium) then it goes into the blood and then to all the organs and brain to provide anesthesia
What state are inhalants administered as
Vapors
What is the vapor pressure
The pressure exerted by a vapor existing in equilibrium with its liquid state
What is the critical temperature
The temperature above which only gas exists
What is the boiling point
The temperature at which the vapor pressure equals the vapor pressure of the surroundings
How could you determine the partial pressure or the total pressure of a container
Use Dalton’s law of partial pressure
P total= P1+P2+P3….
What is the volume percent of inhalants
the relationship between vapor pressure and maximal pressure
(Vapor pressure/barometric pressure (760 if at sea level)) x 100 = vol%
What is the blood/gas partition coefficient
The solubility of vapor in the blood aka the ratio of the vol% of vapor in one phase (in the alveoli) compared to the vol% in another (blood) aka how much the vapor likes to stay in the blood
Solubility decreases with what
Increase in temperature
The lower the partition coefficient of a vapor
The more the vapor wants to stay in the alveoli
The lower the solubility of an inhalant
The faster the action- gets through blood and to brain quickly
What is the fastest way to gas an animal down
With a nonrebreathing system with sevoflourine (low solubility)
What is the potency of a drug measured as
The MAC- the minimum alveolar concentration- the concentration of an inhalant required to prevent movement in 50% of a given population when exposed to a noxious stimulus
The lower the Mac
The more potent the anesthetic
T/F MAC is additive
True
What type of factors increase MAC
Hyperthermia and hypernatremia and increasing excitatory neurotransmitters (happens with drugs like cocaine and amphetamines)
What type of factors decrease MAC
Older age, hypothermia, hyponatremia, pregnancy, hypoxemia, severe hypotension, severe hypercarbia (lots of CO2), metabolic acidosis, other anesthetics
Does the duration of anesthesia impact MAC
No
How do alkalosis, gender, hypertension, and anemia impact MAC
Trick question! They don’t
What is the only electrolyte that affects MAC
Sodium (hyper and hyponatremia)
What determines if the anesthetic in the brain produces anesthesia
Partial pressure, not concentration
How do you increase the delivery of the anesthetic to the alveoli
Increase the inhaled partial pressure (delivery) or increasing the alveolar ventilation
Increase respiratory rate, increase the anesthetic gas (vaporizer flow), minimize the volume of the breathing circuit, increase the oxygen flow rate
The partial pressure in the alveoli equals
The partial pressure of the brain
How do you decrease the uptake of the anesthetic gas
Decrease the solubility, decrease the cardiac output, decrease the alveolar-venous partial pressure difference
If the cardiac output is lower how will it impact the alveolar partial pressure
It will increase the alveolar partial pressure
An older calmer dog with a lower heart rate vs. a young dog with a high heart rate, who will need more inhalant
The younger dog with the higher cardiac output will require more inhalant (think of the higher cardaic output being able to “dilute” out the anesthetic gas faster)
What is the alveolar-venous partial pressure difference and why is this clinically relevant
The different in the partial pressure of the inhalant in the venous blood vs. alveolar
this impacts how fast the inhalant gets distributed/ moved to the target location (this is how fast you run the marathon vs. the MAC is the length of the marathon)
When you flush the line of the anesthesia machine what are you doing
You are changing the partial pressure so it makes the inhalant more likely to want to move out of the animal (wants to move to the area without inhalant gas pressure so moves to the now “clean” anesthesia line)
T/F the longer you are under anesthesia will not impact how long it takes to wake up
False, the longer you are under anesthesia the more saturated the body is and the longer it will take to clear the inhalants out of your body
Less soluble inhalants are cleared from the body how
They are cleared faster, animal will wake up faster
What impacts recovery
How long the animal was under and the solubility of the drug used (so the type of inhalant)
Inhalant A is highly soluble in blood and inhalant B is not, how does this impact induction
B will have a faster induction
MAC is the measure of what and among multiple inhalants is what
MAC is a measure of potency and is additive among multiple inhalants
What is the measure of induction
Solubility
