MAC help

charles-thor · Sep 19, 2004

MAC is a measure of potency, and it's really not much more than the ED50 of any other drug. Keep in mind what MAC is (50% pts will not move to a surgical stimulus at a given partial pressure of a volatile agent at 1 atm) and is not. Also, MAC is additive, so 0.5 MAC agent X + 0.5 MAC agent Y = 1.0 MAC, and thus 50% pts... It helps to have an understanding of what increases and decreases MAC, so you can administer your anesthetic appropriately.

If you can get your hands on a copy of Anesthetic Uptake and Action by Eger published in 1974, I highly suggest that you read the sections on MAC, in addition to those dedicated to uptake and distribution. Of all the texts that I've looked at, this one made the most sense. Unfortunately, it's out of print, but I found a used copy for something like $20 online. Good luck.

athomas91 · Sep 19, 2004

there's also a good book on inhalation anesthetics...can't remember the author...

air · Sep 19, 2004

Go to new england school of nurse anesthesia website.

One of the instructors put online a nice explanation.

That concept of MAC set me back some 24 to 36 hours to master the whole concept and take a test on it.

Try one of those Dannemiller Foundation series, I think Dr. Edmond Eger out of San Francisco, Ca has a 90 minute lecture on one of those CD's. It should be available in your program library.

NCgirl · Sep 19, 2004

I just wanted to say that I too was quite confused about MAC, etc., but watched the Eger DVD's, and it made much more sense. I highly suggest them to anyone just starting out in this field!

gravitycure · Sep 19, 2004

thanks for the help. i will look for the eger book from 1974. i also have seen the DVD's that came out last year. they helped but it is a difficult concept.

gc.

Quincke · Sep 19, 2004

If you understand the definition and that MAC is additive, that's a good start. MAC is a convenient way to compare the potency of the different inhalation agents. If I understand it correctly (correct me if I'm wront), MAC hours are more important in some aspects of anesthesia than others, such as the likelihood of certain side effects. A MAC hour is based on both the length of time and the MAC level. For example, 2 hours at 1 MAC = 2 MAC hours, but 1 hour at 2 MAC = 2 MAC hours also.

I think it takes everyone a while to fully "get" MAC and the information that is generally presented with it. The books that helped me the most were Eger's Pharmacology of Inhaled Anesthetics and the DVDs that went w/ it and Longnecker (good tables that tell you what increases and decreases MAC).

Good luck!!:)

jwk · Sep 19, 2004

If you understand the definition and that MAC is additive, that's a good start. MAC is a convenient way to compare the potency of the different inhalation agents. If I understand it correctly (correct me if I'm wront), MAC hours are more important in some aspects of anesthesia than others, such as the likelihood of certain side effects. A MAC hour is based on both the length of time and the MAC level. For example, 2 hours at 1 MAC = 2 MAC hours, but 1 hour at 2 MAC = 2 MAC hours also.
I think it takes everyone a while to fully "get" MAC and the information that is generally presented with it. The books that helped me the most were Eger's Pharmacology of Inhaled Anesthetics and the DVDs that went w/ it and Longnecker (good tables that tell you what increases and decreases MAC).
Good luck!!:)

"MAC-hours" used to be an important concept many years ago with a lovely little inhalatoin agent called Penthrane. It was a wonderful agent for limited circumstances, OB in particular - there was even a patient-held Penthrane Inhaler as I recall. The only problem was it turned out to be highly nephrotoxic, and if you used more than 2 MAC-hours or something like that, your renal complications shot up significantly.

sweetsleeper · Sep 19, 2004

Think of MAC (minimal alveolar concentration) this way: With a certain concentration of say Sevo 1 MAC, that means that half the patients tested at that level of percentage of agent moved to noxious stimuli, and half did not.

It is simply a measurement. It has been several years, but that is what I remember it as. Don't go asking me alot of specifics, I don't remember all of them! Hope this helps. sweetsleeper CRNA