Important aspects of volatile (gas) anesthetics: (FA2020 p549):

• MAC (minimum alveolar concentration): essentially the ED50 for inhaled anesthetics, this is the minimum concentration of anesthetic that causes a response in 50% of patients
• LOW MAC means HIGH potency - more potent drugs would have a lower minimum amount needed to be present in the alveoli in order to exert their effect.
• LOW MAC is related to HIGH lipid solubility (higher oil/gas partition coefficient) - more lipid soluble agents tend to be more potent because of their increased ability to cross the BBB
• MACs are additive (i.e. one gas at 1.5 MAC = two gases at 0.75 their respective MACs)
• Blood/gas partition coefficient: an expression of solubility; anesthetics with a low blood gas partition coefficient have a rapid onset/offset
• i.e. LESS plasma solubule anesthetic = FASTER onset/offset
• This is because less plasma soluble agents will "fill up" their maximum amount in the blood reservoir quicker and thus are pushed down their concentration gradient into the brain quicker; i.e. they quickly saturate the blood and will move on to affecting the brain quicker
• MAC and blood/gas partition coefficient also tend to be inversely related -- higher MAC = lower blood/gas partition coefficient and vice versa; thus many of the more potent anesthetics have a longer time for onset/offset