Tag: Anesthetics

Sorry to be late tonight.  I was occupied earlier this afternoon than I had planned and got a late start.  However, I wanted to produce a quality piece even though it did not post exactly at 9:00.

This the last part in our three piece series on anesthetics.  We have covered general anesthetics of the inhalation type and of the IV type, and now will discuss local anesthetics.  The primary difference betwixt general and local anesthesia is that in general anesthesia the patient is generally unconscious or at least highly sedated, whilst in local anesthesia the awareness of the patient is generally not impaired, although sometime they are sedated by other agents.

The term “local” is not as descriptive as one might think.  While it is true that very small areas can be anesthetized, often much larger areas are.  By the way, it is likely that local anesthesia is much more ancient than general anesthesia, for reasons to be explained later.

Last week we started this three part series with inhalation anesthetics, and here is a link.  This week we shall discuss injected anesthetics, and finally shall finish up the series next week with local ones.

We should once again stress the difference betwixt anesthetics and analgesics.  In general (this rule is not 100%, but darned close), anesthetics render the patient unconscious so that surgical procedures can be performed with no physical pain during the procedure.  In addition, many anesthetics cause muscle relaxation which makes surgical procedures less traumatic.

Analgesics, on the other hand, are not designed to render the patient unconscious, but rater to moderate the sensation of pain caused by many reasons.  A few analgesics can be used as anesthetics, but in general depress the medulla such that respiratory difficulties often result.  

Anesthetics are as essential to modern surgery as are sterile fields and antiseptics.  There are a couple of reasons for that, the most obvious being that the patient most likely could not survive the shock and pain of any but the least invasive procedure with out them.  Interestingly, the use of anesthetics in the modern sense is quite recent, dating only from the mid 1800s.

There are two major divisions of anesthetics, general anesthetics and local ones.  General ones cause a more or less complete loss of sensation and consciousness, whilst local ones cause a loss of sensation for only a relatively small part of the body and leave the patient conscious.  In addition, general anesthetics fall into two wide classes, inhalation ones and intravenous ones.  We shall discuss, in general terms, inhalation general anesthetics tonight.