Erin's Pharm Exam 3 Flashcards
Boyle’s law states that given a constant temperature, pressure and volume of gas are…
inversely proportional
Applying Boyle’s law:
1. As PPV begins, the bellows ______
2. _____ increases within ventilator and circuit
3. Anesthetic gases flow from __ pressure to __ pressure, aka into the _____
- contract
- pressure
- High to low, the lungs
What influences the pharmacokinetics of volatile anesthetics?
(old) Aging!
So…
* decreased lean body mass
* increased fat
* increased Vd for drugs (especially for more fat soluble)
*Decreased clearance if pulmonary exhange is impaired
*Increased time constraints due to lower CO
What is the main effector site for volatiles?
The brain!
Diffusion depends on 3 things. List them
- Partial pressure gradient of the gas
- Solubility of the gas (diffusion)
- Thickness of the membrane
Fick’s diffusion law
Once the molecules get to the alveoli, they move around randomly and begin to diffuse into the pulmonary capillary
Graham’s law of effusion states that smaller molecules effuse ____ dependent on _____
fast, solubility (diffusion)
Although Oxygen is smaller than Carbon dioxide, carbon dioxide is 20x more diffusible. Why?
Carbon dioxide is very soluble!
This is the process by which molecules diffuse through pores and channels without colliding
Effusion
Alveolar pressure is an indicator of these two things
-Depth of anesthesia
-Recovery from anesthesia
What four things are included in the partial pressure gradients between the anesthetic machine to alveoli (aka input)
-Inspired partial pressure
-Alveolar ventilation
-Anesthetic breathing system (is there a lot of rebreathing?)
-FRC
What three things are included in the partial pressure gradients between the alveoli to blood?
-Blood: gas partition coefficent
-Cardiac output
-A-v partial pressure difference
What 3 things are included in the partial pressure gradients between the arterial blood to brain?
-Brain: blood partition coefficent
-Cerebral blood flow
-a-v partial pressure difference
Which two partial pressure gradients make up “uptake”?
Alveoli to blood
Arterial blood to brain
The impact of PI on the rate & rise of PA is known as the…
concentration effect!
The higher the PI of a volatile, the more rapidly ____ approaches ____
PA approaches PI
The impact of the inhaled concentration of an anesthetic on the rate at which the alveolar concentration increased toward the inspired (FE/FI) is known as the
concentration effect
Explain over pressurization..
What happens with sustained delivery?
Explain the second gas effect
The uptake of a high volume gas (N2O) accelerates a concurrently administered companion gas (volatile)
Explain what is happening here
This is the second gas effect! Halothane with 70% nitrous approaches FE/FI faster than halothane with 10% nitrous
How much and how fast does nitrous diffuse into air-filled cavities?
Up to 10L in the first 10-15 minutes
1 hour of nitrous for retinal repair results in
-Increased intraocular pressure during retinal repair
-Retinal artery vision loss
Explain how respiratory rate impacts PA and PI
Increased RR speeds PA towards PI and therefore speeds the induction of anesthesia
How does decreased PACO2 impact the speed of induction
Decreased PACO2 decreases CBF and limits speed of induction
