Nagelhout videos- Volatiles Flashcards
4 components of general anesthesia
- Amnesia - loss of memory
- anesthesia- loss of consciousness
- Analgesia - freedom from pain (Inhalationals are poor analgesics- think- that’s why a lot give fentanyl during timeout- to blunt the sympathetic response to pain)
- Muscle relaxation
How many stages of anesthesia
4
Stage of anesthesia from when pt is first exposed to anesthetic agent to the time they lose consciousness
Stage 1
What does anesthesia produce
loss of consciousness
Stage 2- pupils dilated or constricted
dilated - body is thinking wtf is going on
+nystagmus due to cerebral cortex suppression
Why does the excitatory phase of anesthesia happen?
Because the inhibitory pathways are affected first and you go to sleep, then you have the excitatory pathways which are harder to anesthetize.
so during the excitatory phase you can kind of say you have unopposed stimulatory neuronal pathways acting up before they become anesthetized
*Patient not deep enough yet
Stage of surgical anesthesia
Stage 3
Stage 3 of anesthesia begins with what?
The onset of regular, rhythmic respirations
What’s the first airway reflex to get knocked out?
Swallowing > wretching/gagging > vomiting
- also the last to come back, which is why it’s important to look for swallowing as your emerging the patient
- if they can swallow, they can protect their airway (gag/cough reflex has returned)
Explain MAC - minimal alveolar concentration
*the dose of an anesthetic
How much gas do I need to have in your lungs so you don’t move when the surgeon cuts (in 50% of population)
The absolute minimum of Fio2 you can give of o2 with anesthesia
30%
Why can you only give 70% nitrous?
Because you at minimum need to have 30% oxygen in the lungs
Blood gas solubility of nitrogen
0.014
(nitrous = 0.47) (~ 34x more soluble) - occupies a larger volume of space
What age is MAC the highest in?
6 months old
How much does MAC decrease with age?
6% every decade after 40yo
Why do kids go to sleep faster than adults despite faster metabolism and faster cardiac output?
They breathe faster. Faster you breathe in the anesthetic, faster you go to sleep.
How is MAC affected by pregnancy?
No change
-increased CO (slower induction) + increased RR (faster induction) = cancels eachother out
I’m gonna say no and that MAC is decreased due to increased progesterone - decreases 30-40%
Do fat people go to sleep faster or slower?
Neither. Same time as the non-obese person.
-Yes they have more fat but fat gets very little blood flow (anesthetic goes to VRG and then muscle before going to fat)
Do fat people wake up faster or slower?
Slower - especially if it’s a long case (2-3hrs) - “Reservoir effect” - inhalational agents are so lipid soluble that it will remain in the fat . More fat = more absorbed inhalational to get rid of
What are the volatile anesthetics and why are they called that?
What about non-volatile anesthetics?
Iso, Sevo, Des
because they come as a liquid and need to be vaporized into gaseous form . You need to “volatilize” aka “vaporize” them
Nitrous is the only non-volatile inhalational agent (supplied in gaseous form)
What is the only inorganic molecule? And what does that mean?
What are all the others?
Nitrous oxide - means it doesn’t have a carbon molecule attached to it
All others = halogenated ethers (contain a carbon molecule ROR/C-O-C bridge, ether bridge)