ETOH abuse and MAC

versatile_kat · Jan 30, 2005

That was exactly my point. The low lipid soluble inhaled anesthetics have a VERY LOW rate of metabolism. Even if enzyme induction lead to a doubling of metabolic rate, there would still be a minimal effect on MAC.
Ethanol has effects on many receptors including GABAa, serotonin (5HT3A, ion channel), NMDA, and neuronal nicotinic acetylcholine receptors. Inhaled anesthetics also work on these receptors. Chronic alcohol consumption leads to the development of tolerance, or a reduced behavioral or physiological response to the same dose. Cross-tolerance can develop, i.e. receptor changes due to chronic etoh consumption can reduce the receptor's response to other drugs, in this case, inhaled anesthetics.
(paraphrased from Goodman and Gilman).
An Yogi

Thanks a lot An ... that makes me feel a little better about my thinking process.

BigDave · Jan 31, 2005

Yeah, I saw that only 2-3% metabolism for sevo in my PDA Miller after talking up the hepatic process. Thanks Mike and an yogi!

DIVER CRNA · Feb 1, 2005

Would someone mind explaining why chronic ETOH abuse increases MAC? I'm thinking it has something to do with down-reglation of GABA receptors but can't convine myself of it ... am I way off base? Thanks in advance!
- Kat

I agree with p450 induction and its indirect relationship with increasing MAC. Little effect should be noticed if a vital capicity pure inhalation induction is utilized. As stated by others most traditional inductions utilize several iv agents that are metabilized by microsomal and non microsomal systems that would attribute to increasin MAC requirements--jeff