What is Anesthesia? Get the Facts

Have you ever wondered, what is anesthesia?  Strictly speaking, it is the absence of sensation.  So when I was 16 and underwent an MRI for my knee, how much anesthesia did I receive?

I actually didn’t receive any anesthesia during my MRI, but I didn’t need it.  Why?  Because I fell asleep during my MRI despite the loud noises and being placed in a small tube.  I actually could not believe I fell asleep, but I did.

Now imagine a patient who has severe claustrophobia and who needs an MRI.  There is not going to be any surgery taking place, but the patient may need anesthesia to eliminate the “painful” stimulation of being inside of a small tube for an hour.  Or the patient may have severe back pain and not be able to lie flat without anesthetic medicines.   Perhaps the patient is a child who is unable to remain still during the MRI.  It depends on the patient, the family, the procedure, the surgeon, the situation, the anesthesiologist, and multiple other factors to determine the level of anesthesia needed.

So what is anesthesia exactly?  Strictly speaking, it is the absence of sensation.  As you can see, there are different levels of absence of sensation depending on what sensation you are referring to, though.  Let’s use another example from the world of dentistry.

At the dentist’s office, you are given local anesthesia so that you do not have the sensation of having a root canal performed.  But often times, you may feel pressure in your mouth, gums, or teeth as the dentist is working.  Is this an anesthetic failure?  Absolutely not.  Some patients are able to tolerate this level of anesthesia without any problems.  But others might need or desire a deeper level of anesthesia to be comfortable.

So intravenous medicines can be given by a trained professional.  This can cause you to take a nap or feel more relaxed so that the actual process of the dentist working in your mouth does not bother you.  But what if you have a large area in your mouth that needs to be worked on and local anesthesia cannot get to this area?  Or what if the intravenous medicines providing relaxation are just not enough to provide comfort?

The next step could be a general anesthetic provided by even more powerful medicines, which renders you unconscious.  At this point, you are unaware of your surroundings and are completely asleep.  Your mouth can be worked on without you knowing about it at all.

You can see from this simple example that anesthesia is not easy to define.  Let’s look at it from another angle.

What if the dentist’s patient was now a small child?  Local anesthesia given by injection could keep the child from feeling the sensation of pain in the area of the tooth, but the sensation of not being in the parents’ arms could be too frightening.  This sensation could be eliminated by giving some relaxing medicines to the child.  But the sensation of sound and hearing a drill might still be present.  So general anesthesia would be the next choice for anesthesia.  But is this safe in a child?

The point is that there are different levels of anesthesia.  From being completely awake to being completely asleep and unconscious during general anesthesia, it is a spectrum.

Anesthesiologists provide anesthesia for patients who might be too ill to have any anesthetic medicines given to them during a procedure.  In these cases, we are present on standby in case there is an emergency.  We help hand surgeons when they perform carpal tunnel releases and sometimes will provide anesthesia medicines that numb just the arm for these cases.  Mothers undergoing caesarean sections can be rendered insensate from the chest down with spinal or epidural anesthesia medicine.  For major surgeries, patients are completely asleep and unconscious under general anesthesia.

Depending on the type of anesthesia needed (or the lack of sensation needed), one medicine can be used or several medicines.  A general anesthetic usually includes hypnosis or unconsciousness, amnesia, immobility, analgesia, and control of sympathetic responses to surgery.  Amnesia entails the inability to remember things that occur during surgery.  Analgesia is the relief of pain.  Controlling sympathetic responses to surgery means that we try and limit the fight or flight response of your body to surgery.  Unconsciousness means you are obviously asleep.  Immobilty refers to the need for a patient that is not moving in order to facilitate the surgical field.

Depending on the procedure though, a general anesthetic may require less or more of one of these factors.  But the common theme with general anesthesia is that you will be unconscious during the time the anesthetic is being administered.  That could be for a few minutes (an endoscopy procedure) or many hours (for instance a heart surgery).

Please check out some other posts to follow that will describe what type of anesthesia to expect for various types of procedures.  And we also plan on discussing how anesthetic medicines work in the future.  Interestingly, the exact mechanisms behind general anesthesia are not completely understood at this time.  But rest assured, your anesthesiologist is looking out for your best interests and safety when you are undergoing anesthesia.

Feel free to leave some comments or help us get our forum started if you get a chance.  We want to learn from you and see what your experiences with anesthesia have been all about.