Subject: What are the types of anesthetic?

My teacher (an ex-nurse) told us there are four types - topical, local, 
general and relative.  I checked Dorland and found three types - topical, 
local and general.  I also searched the net and found that there is also a 
type called regional.  One source listed the following:- Anesthesia is divided 
into four basic categories: 
general anesthesia 
regional anesthesia 
local anesthesia 
sedation 

I couldn't find the type "relative" as relayed by my teacher.  Is there such a 
type called "relative"?  Same as "sedation" above?  I am confused.  Please 
explain.

My teacher described "relative" as awake but sleepy, conscious sedation, 
euphoria and the exmaple given was nitro-oxide or laughing gas.

I am totally lost.  Please help.  

Re: What are the types of anesthetic?