I’m curious what mechanism is at work here.
Edit: Thanks for the responses. I get it now. Obviously I am still enjoying the discussion RE: the finer points like memory, etc.
In: Biology
Just to add a little bit to the other, very good posts: I learned in a class about general and local anesthesia, that the surgeon will use a local even if you are under general anesthesia. This is because your body still responds to pain stimuli even if you are under. So the numbing is to keep your heart rate and respiration from increasing in response to the pain receptors triggering your autonomic nervous system
For starters, you can’t compare sleep and unconsciousness. Just because you’re not awake in both states, it doesn’t mean that they are the same. Sleep is a highly active state of (un)consciousness, in which the brain is going through different levels of sleep patterns. At some points, the brain is even more active when we are sleeping, compared to us being awake.
Drug induced anesthesia is a very complex mechanism and is executed differently, depending on surgery an patient. Shutting off the pain is not very hard, we have a variety of pain killers that do that pretty well. Unfortunately, they have a little side effect. The stronger the pain killer, the faster it stops you from breathing. That is one reason, why you are brought to unconsciousness. You would think, that giving you just the drug for “unconsciousness” is enough for the surgeons to operate on you, but that is not true. You are not “there” to experience, or remember anything (sometimes patients do wake up during surgery, but don’t feel or remember anything), but your body still reacts to pain. Your blood pressure rises, heart rate increases etc. These effects are counterproductive for surgery, that’s why you are given pain medication, even though you are unconscious.
What if anesthesia just made you forget the excruciating pain afterwards ?
(I know it’s not the case, just wanted to share a rather terrifying thought)
Technically, we don’t REALLY know how anesthesia works.
Generally, it works by inhibiting activity in the central nervous system, because the drugs target specific receptors in the brain that reduces neural activity and receptiveness to pain. That’s the quick and dirty version. The thing is that we don’t know exactly WHY. There is a general idea and hypothesis about it, but we don’t truly know all the mechanics at work and why it works that way. We know what the drugs do and the effects on the body, but we don’t know the exact mechanisms that causes the anesthetic drugs to have that effect.
Anaesthetist here.
There are a few elements to general anaesthesia for surgery, at the minimum you typically get something to render you unconscious, and something else to reduce pain.
In my country this is most commonly propofol (the anaesthesia drug) and fentanyl (strong opioid), but there are quite a few alternatives and combinations we use for both purposes.
As for “feeling” pain, it’s actually slightly more complex. Pain is a conscious experience, the pain receptors on your skin or organs detect noxious stimulus > send signal to the brain > it generates a conscious unpleasant sensory and emotional experience that we call “pain”.
Now when someone is under anaesthesia, a big part of this chain of physiological process actually STILL takes place. The pain receptor still works, it still sends signal, and it still arrives in the brain. In fact we do see it in the form of increased heart rate and blood pressure etc.
Through intravenous painkillers (eg opioid) and local anaesthetic etc we do reduce these signals somewhat at various point of the chain, mostly so that when you wake up eventually you are not in huge pain; however it is perfectly possible for the entire chain to stay intact, it’s merely your being not conscious to experience the unpleasant emotional experience.
I’ve never had a surgery, and my biggest fear is that if I have one I will feel absolutely everything without being able to move/react. But once you “wake up” from it it’s erased from your memory so you can’t remember the nightmare you just went through.
I’m sure this is not the case, but the thought has crossed my mind more times than I’d like to admit.
Anesthesia means you’re asleep. Analgesia means without pain.
Both of these are done so You don’t remember the surgery, nor feel it.
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