Inhaled anesthetics Flashcards
Nitrous oxide CNS effects
Increases CBF, may decreased sensory evoked potential‘s
At sea level a full MAC is unattainable 105%
Cardiovascular effects of nitrous oxide
There is a tendency to stimulate the sympathetic nervous system with a small or a slight increase in heart rate blood pressure and cardiac output
Can increase PVR in adults
Respiratory affects of nitrous oxide
Minimal change in minute ventilation and PaCO2
Hypoxic drive is markedly depressed
Diffusion hypoxia at the end of the case
How does nitrous oxide cause megaloblastic anemia and peripheral neuropathy
It oxidizes COBOL Adam in B 12 which inhibits methionine synthetase used in Mylan formation
This also inhibits thymidylate synthetase used in DNA formation
At what age is MAC the highest
Six months
What causes Mac to be increased
Higher central neurotransmitters amphetamines MAOIs hyperthermia chronic ethanol hypernatremia
What decreases Mac
Age hyperthermia pregnancy acute ethanol other anesthetics
Which property of the anesthetic correlates with it’s Mac
Solubility in olive oil
Not blood gas solubility which correlates with FA/FI
MAC BAR
Block autonomic response equals 1.5 Mac
Meyer-Overton principle
Lipid solubility and potency correlation
MAC awake
O.3 MAC
ED95 of volatiles
1.3 MAC
MOA of inhaled anesthetics
They bind ampiphillic portions of proteins
There is no social mechanism of action but does alter multiple ion exchange
What two things do you need to know for vaporizer filling errors?
Vapor pressure
MAC
Vapor pressure of des, sevo, and iso
Is vapor pressure pressure or temperature dependent?
Des 670
Iso 240
Sevo 160
Temperature, doesn’t matter what atmosphere you’re in
Iso is mistakenly placed in a sevo vaporizer, and dialed in at 4%. What MAC are you reliving of iso?
You are overdosing the patient because iso has a higher vapor pressure at 240
4% is about 3.2 MAC of iso, yikes
What is the recommended highest concentration of anesthetic ambient air?
2 ppm
If combined with nitrous, 0.5 and 25 ppm of NO
What what would happen if you put des in an iso vaporizer?
Does has the highest vapor pressure therefore you would get a very high overdose very quickly
That is why des is kept in it’s own special vaporriser
Which volatile anesthetic is the least soluble?
Des 0.47
Sevo 0.68
