Definition of Anesthesia?

[medstudam]

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I just started my Anesthesiology rotation and yes, I know nothing about Anesthesia. Well, I've been reading Baby Miller and Secrets and have not yet found the true definition of anesthesia. I am really trying to understand this stuff and I know it is more than just providing analgesia, so here is what I have derived so far, so help me out!
The four components of Anesthesia:
1) Amnesia ---> achieved with for example Versed
2) Analgesia ---> Fentanyl
3) Unconsciousness/Induction ---> Propofol / Etomidate
4) Paralysis ---> Succ or Nondepol like Roc or Vec.

Is there more??

Also, what I've understood with the gases (Sevo/Iso/Des) is that they provide these four elements after the patient has been given the above drugs IV and then switched to the gases after intubation. Am I on the right track with this? Thanks!!

 

[Justin4563]

I just started my Anesthesiology rotation and yes, I know nothing about Anesthesia. Well, I've been reading Baby Miller and Secrets and have not yet found the true definition of anesthesia. I am really trying to understand this stuff and I know it is more than just providing analgesia, so here is what I have derived so far, so help me out!
The four components of Anesthesia:
1) Amnesia ---> achieved with for example Versed
2) Analgesia ---> Fentanyl
3) Unconsciousness/Induction ---> Propofol / Etomidate
4) Paralysis ---> Succ or Nondepol like Roc or Vec.

Is there more??

Also, what I've understood with the gases (Sevo/Iso/Des) is that they provide these four elements after the patient has been given the above drugs IV and then switched to the gases after intubation. Am I on the right track with this? Thanks!![/QUOT


Yes the gases do provide all four of t he above but usually if you want to achieve paralysis you will need a really high concentration of gas so we use muscle relaxants to achieve this. T hat way we can back off on our gases. The other thing is something called balanced anesthesia where you give some versed and fentanyl up front to achieve amnesia and analgesia then we induce.. intubate or lma then we turn our gases on.. The gas now can be further decreased because of the versed and fentanyl you gave up front.. You have to be careful when you give all this because if you do and have to wake the patient up in like 20 minutes.. the versed and fentanyl will still be on board and can delay awakening. the gas typically wont delay awakening because you can blow that stuff off.. also the concept of MAC. Know that MAC is additive. so the iv drugs contribute to the mac. thanks for your post. keep on truckin.. and asking questions

 

[rn29306]

Do inhaled gases actually provide analgesia similar to opoids? Or is it the attenuation of the SNS that is assumed to be the analgesic component of inhalational gases?

Miller states that the characteristics of an ideal inhalational anesthetic:
- absence of flammability
- easily vaporized at ambient temp
- potent
- low blood solubility to ensure rapid induction and recovery from anesth.
- minimal metabolism
- compatible with epi
- skeletal muscle relaxation
- suppression of excessive SNS activity
- not irritating to airways
- bronchodilation
- absence of excessive myocardial depression
- absence of cerebral vasodilation
- absence of hepatic or renal tox.
There is no statement about analgesic activity. The response to the OP was that gases provide all elements of anesthesia alone. We were taught that this is not true. Certainly you can maintain a pt after induction with an analgesic as preop, but to say that the inhaled anesthetics provide all aspects of anesthesia (esp analgesic properties) I was taught to be incorrect. Prof also stated that ketamine was the agent currently available to provide close to all the requirements for anesth, but with the drawback poor (ie. not assured) muscle relaxation. Your thoughts?

Thanks for the clarification.

 

[UTSouthwestern]

Isoflurane Reduces Glutamatergic Transmission in Neurons in the Spinal Cord Superficial Dorsal Horn: Evidence for a Presynaptic Site of an Analgesic Action

That was an article I read in 2004 that was a well designed in vitro analysis. There are several others that seem to confirm that volatile anesthetics do provide analgesia, though not to the level of opioids and certainly not beyond the termination of the anesthetic.

 

[undecided05]

nope... you know everything now; congrations.

As a friend of mine told me, you may think you know what anesthesia is about, but until you're doing it as a resident and even then, it takes a few months to begin to figure out what you're doing, why you're doing it, and the general principles of anesthesia.