Medical-types: can I be immune to lidocaine?

Factual Questions
1

Short version: I had a polyp on my vocal cord (removed surgically about 2 months ago), but at 2 of my office visits, the doctor used a viscous lidocaine solution to numb me up a little before scoping me. He fills a little cup with this syrupy goo, and I swish it around and then I get to sit and wait while it takes effect. Doctor says it should last about an hour. 2 visits, weeks apart, both times, it wears off in a matter of 15 minutes or less. The first time, it wore off so quickly, they had to dose me again, because the effect was gone before he got back from waiting for it to take effect.

Does he have a bad batch of this stuff, or am I immune to it? Is it likely that I’m only immune to this viscous solution, or is it more likely that I’m simply lidocaine-proof in general? If the latter, is this something I need to make sure future doctors are aware of?

This worries me because I know (well, I gather from watching TV) that lidocaine is a very commonly-used anesthetic, and I don’t want to wind up going in to the ER after a car accident or something and having them dose me with it before doing something fun like setting a broken bone.

FWIW, I’ve never had any similar problem at the dentist (I know, that’s probably novocaine, but just in case, I thought I’d mention it).

2

It happens (maybe), but must be extremely rare. Look here.

3

The effects of topical or local anesthesia go away because the circulatory system removes the chemical from the area. Lidocaine is sometimes mixed with a vasoconstictor to slow down your bodies attempt to remove the drug. Is your oral cavity inflamed? Increased blood flow to an area can reduce the length of local anesthesia effects.

4

It is now. [rimshot]

No, it was not inflamed, but that’s good info worth having.

Great. I might finally be eligible for Xavier’s School, and this is my mutation?

Maybe I can make up for it with a really wicked superhero name.

5

Anyone else pop in thinking the OP was asking about iocane?

6

Ironically, it was my post in the “I’ve just discovered The Princess Bride” thread that reminded me I hadn’t ever asked the TM’s input on this question!