Anesthetics

Anesthetics are kind of scary. Well, not so much the localized ones, but the ones that put you under during surgery. What would spur me to say such a thing? For one thing, anesthesiologists have no idea how the drugs that they are giving you fully work. If they say that they do, they're not being entirely truthful. We know some parts of the mechanism of action of most systemic anesthetic agents, but we have yet to learn the whole story.

One of the problems with determining the exact action that anesthetics have on the body is that they are usually incredibly small and simple molecules. The most simple structure is the noble gas xenon. Of course, we don't really use that so much in the United States because it's expensive, but Russia does because they have deposits of it. Even alcohol at high enough concentrations induces anesthesia, which is rather part of the problem with overdosing on alcohol.

Anesthetics also have a relatively small margin of error for dosing. The line is fine because being in absentia from control of your body and sensation is pretty close to death, and at the other end, consciousness is pretty close as well. In addition, the anesthesiologist is guessing how large a dose you should be given. Different people metabolize different compounds at different rates and distribute them at different rates to the body. There are too many variables at work for anyone to currently know what exact dose should be given.

There is a bright side, of course. For surgery, at least, the maintenance dose of a total anesthetic is usually given via inhalation. Why is this good? Well, inhalation is one of the fastest ways to absorb something into the body. This means that the person monitoring you sees almost instant results from changes in dosing. It's also why cigarettes are such an effective way of delivering nicotine and why crack cocaine is used, but I digress. The other advantage of inhalation is that to bring someone out of an anesthetic state quickly, all you have to do is remove the mask delivering the drug. The patient breaths out whatever amount of the drug that's in the air of the lungs and then because the concentration of the drug in the air of the lungs is lower than that of the concentration in the bloodstream, the drug moves out of the blood to the lungs and is continuously exhaled. If that doesn't make sense, it's probably because I've become so used to thinking about concentration differentials across membranes and I've lost touch with explaining it in simpler terms. It's important to note that because alcohol is ingested, it's more difficult to remove quickly, which is why alcohol induced anesthesia is a very bad thing indeed.

Before I end this post, I'd like to mention how local anesthetics work and why they aren't so much of an issue. These are things like novacaine that the dentist uses on an area of the body and we understand their mechanisms quite extensively. These compounds are very complex compared to systemic anesthetics with respect to their structures and can be quite large molecules. Usually, they just stop the messages sent via the nervous system of a particular region where the drug is injected from making it to the brain. This is accomplished by interfering with the action potentials of a nerve either where the action potential begins or somewhere along the neuron's axon, which is the long, narrow bit of a neuron. Explaining it fully requires explaining how an action potential works, which is not my intention with this post, so I'll leave it at that for now.

This has been a rather technical post, more so than I had hoped when starting out, so if I have time later in the week I'll try to make a much lighter one.