Local anesthetic resistance

[callmeanesthesia]

I have encountered a few patients with local anesthetic resistance. Usually I notice when I numb them for an RF and they still flinch when I poke them with the RF cannula, and no matter how much lidocaine I add, or how long I wait, they are still in pain as soon as I start the ablation. All of them say the dentist has a hard time numbing them and it usually takes 3-4x the usual amount if it works at all.
I’ve had success with several of those with switching to 0.25% bupivacaine. In most of them, that works like it should - I just have to pause a little longer than I usually would but they numb up great.
However, I have one patient where that doesn’t seem to work either. She stopped having the dentist numb her at all because her face got numb but the drilling still hurt. Instead she just meditates through dental work with no local. Lidocaine (1%) did almost nothing - she could discriminate sharp and dull stimuli with her eyes closed on top of a sizeable skin wheal. So I tried with 0.5% bupivacaine. She said the area felt numb, but she could still feel sharp when I tested. She described it as feeling like 2 sensations - first pressure then a second or two later, pain/sharp. Best I can tell, it was anesthetizing to light touch, but not getting the C fibers, hence the slight delay. She does report successful epidurals for delivery, though some were patchy or one-sided. Ideas? Higher concentration? Bicarb? Ropivacaine, chlorprocaine? Must be some sort of sodium channel polymorphism but I’m wondering if there’s a different receptor subtype on peripheral vs spinal nerves that would account for successful epidural vs failed peripheral blocks. Otherwise I don’t understand why an epidural (usually bupivacaine or ropivacaine) would work but not 0.5% bupi. If I could figure it out it would make a great case report, but currently it’s at the “sucks to be you” stage…

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[kstarm]

I have not run into this. I know my partner has and typically uses chlorprocaine with good success and we have some stocked in the procedure suite in case we run into something like this.

 

[fathead88]

Have had the same issue before. Use chloroprocaine, it’ll work.

 

[deleted875186]

I have encountered a few patients with local anesthetic resistance. Usually I notice when I numb them for an RF and they still flinch when I poke them with the RF cannula, and no matter how much lidocaine I add, or how long I wait, they are still in pain as soon as I start the ablation. All of them say the dentist has a hard time numbing them and it usually takes 3-4x the usual amount if it works at all.
I’ve had success with several of those with switching to 0.25% bupivacaine. In most of them, that works like it should - I just have to pause a little longer than I usually would but they numb up great.
However, I have one patient where that doesn’t seem to work either. She stopped having the dentist numb her at all because her face got numb but the drilling still hurt. Instead she just meditates through dental work with no local. Lidocaine (1%) did almost nothing - she could discriminate sharp and dull stimuli with her eyes closed on top of a sizeable skin wheal. So I tried with 0.5% bupivacaine. She said the area felt numb, but she could still feel sharp when I tested. She described it as feeling like 2 sensations - first pressure then a second or two later, pain/sharp. Best I can tell, it was anesthetizing to light touch, but not getting the C fibers, hence the slight delay. She does report successful epidurals for delivery, though some were patchy or one-sided. Ideas? Higher concentration? Bicarb? Ropivacaine, chlorprocaine? Must be some sort of sodium channel polymorphism but I’m wondering if there’s a different receptor subtype on peripheral vs spinal nerves that would account for successful epidural vs failed peripheral blocks. Otherwise I don’t understand why an epidural (usually bupivacaine or ropivacaine) would work but not 0.5% bupi. If I could figure it out it would make a great case report, but currently it’s at the “sucks to be you” stage…

I bet the epidural works because of the fentanyl in the mix, it reduces the concentration of local needed for pain relief by about 50%.

I bet bicarbonate would work, or a higher concentration like 2% lido or 3% chloroprocaine.

 

[callmeanesthesia]

I bet the epidural works because of the fentanyl in the mix, it reduces the concentration of local needed for pain relief by about 50%.

I bet bicarbonate would work, or a higher concentration like 2% lido or 3% chloroprocaine.

No, she described a unilateral block with two of them, and one of them that was absolutely great, with a painless delivery. I had to replace enough epidurals to be of the opinion that the only thing fentanyl was good for was as a bolus to get them through handoff and make it someone else’s (my) problem.

I’ll see if I can get some chlorprocaine. Henry Schein looks like it only has 2% in stock currently, and it’s pricy.

 

[Ferrismonk]

I have encountered a few patients with local anesthetic resistance. Usually I notice when I numb them for an RF and they still flinch when I poke them with the RF cannula, and no matter how much lidocaine I add, or how long I wait, they are still in pain as soon as I start the ablation. All of them say the dentist has a hard time numbing them and it usually takes 3-4x the usual amount if it works at all.
I’ve had success with several of those with switching to 0.25% bupivacaine. In most of them, that works like it should - I just have to pause a little longer than I usually would but they numb up great.
However, I have one patient where that doesn’t seem to work either. She stopped having the dentist numb her at all because her face got numb but the drilling still hurt. Instead she just meditates through dental work with no local. Lidocaine (1%) did almost nothing - she could discriminate sharp and dull stimuli with her eyes closed on top of a sizeable skin wheal. So I tried with 0.5% bupivacaine. She said the area felt numb, but she could still feel sharp when I tested. She described it as feeling like 2 sensations - first pressure then a second or two later, pain/sharp. Best I can tell, it was anesthetizing to light touch, but not getting the C fibers, hence the slight delay. She does report successful epidurals for delivery, though some were patchy or one-sided. Ideas? Higher concentration? Bicarb? Ropivacaine, chlorprocaine? Must be some sort of sodium channel polymorphism but I’m wondering if there’s a different receptor subtype on peripheral vs spinal nerves that would account for successful epidural vs failed peripheral blocks. Otherwise I don’t understand why an epidural (usually bupivacaine or ropivacaine) would work but not 0.5% bupi. If I could figure it out it would make a great case report, but currently it’s at the “sucks to be you” stage…

Usually if you use Bicarb with the local, it'll work better for these patients. Maybe it's an intraneural concentration thing. There's actually dental literature that says if they chew Tums before the local it works better in these patients as well.

I also agree switching to an ester LA sometimes works better too.

 

[NJPAIN]

I believe I have experienced this personally with dental work. I recall a dentist injecting lidocaine multiple times and still experiencing pain. On subsequent occasions responded to carbocaine. Had a root canal once and the endodontist tried every block technique he knew. Even used a high pressure “gun” to inject into the periodontal membrane which did not work. Eventually told me to hold onto the chair and injected into the root. Lots of fun.

 

[callmeanesthesia]

I believe I have experienced this personally with dental work. I recall a dentist injecting lidocaine multiple times and still experiencing pain. On subsequent occasions responded to carbocaine. Had a root canal once and the endodontist tried every block technique he knew. Even used a high pressure “gun” to inject into the periodontal membrane which did not work. Eventually told me to hold onto the chair and injected into the root. Lots of fun.

I found an article from a pain clinic that recruited patients with self-reported history of local anesthetic resistance and tested them with several anesthetics, and if I recall correctly, they had a decent percent that responded to mepivacaine much better than lidocaine. Dentists often use septocaine. You might try a skin wheal of bupi on yourself as well. If you need dental work, do you take your own bottle of mepivacaine?

This patient also described having a root canal and having at least three injections, including around the base of the tooth, and still feeling it. Her whole face was numb for hours afterward but she could still feel pain from the drilling (similar response when I tried to numb her). She said she eventually just told the dentist it was numb so he would get it over with, and suffered through it.

 

[NJPAIN]

I found an article from a pain clinic that recruited patients with self-reported history of local anesthetic resistance and tested them with several anesthetics, and if I recall correctly, they had a decent percent that responded to mepivacaine much better than lidocaine. Dentists often use septocaine. You might try a skin wheal of bupi on yourself as well. If you need dental work, do you take your own bottle of mepivacaine?

This patient also described having a root canal and having at least three injections, including around the base of the tooth, and still feeling it. Her whole face was numb for hours afterward but she could still feel pain from the drilling (similar response when I tried to numb her). She said she eventually just told the dentist it was numb so he would get it over with, and suffered through it.

I might have to bring my own carbocaine. Fortunately, I had a great academic dentist in NYC for many years who I believe routinely used carbocaine. I need to have a tooth extracted and I will need to take this into consideration. This will be the first time having an extraction under straight local.

 

[Baron Samedi]

You have to be a sick masochist to go into dentistry. Anti-dentite, loud and proud.

 

[drrosenrosen]

I believe I have experienced this personally with dental work. I recall a dentist injecting lidocaine multiple times and still experiencing pain. On subsequent occasions responded to carbocaine. Had a root canal once and the endodontist tried every block technique he knew. Even used a high pressure “gun” to inject into the periodontal membrane which did not work. Eventually told me to hold onto the chair and injected into the root. Lots of fun.

I'd find me a dentist who uses N2O if I had this problem and needed a root canal.

 

[NJPAIN]

I'm gonna need more than N20. I hate going to the the dentist to begin with and now I going to use some local oral surgeon who I don't know. I will need lots of Xanax just to get through the door. It's a month wait to get in. In the interim, I'm applying a high concentration prescription fluoride gel to decrease the sensitivity.

 

[Ducttape]

i had root canal done in December.

she kept giving me local because i told her i could still feel a little something not painful (you know, pressure sensation), until i lied because i was tired of keeping my mouth open for so long.

cost me over $1100 for 2 procedures.

 

[NJPAIN]

i had root canal done in December.

she kept giving me local because i told her i could still feel a little something not painful (you know, pressure sensation), until i lied because i was tired of keeping my mouth open for so long.

cost me over $1100 for 2 procedures.

In my day all of the people who couldn't get into med school went into dentistry. So called "rejects". Now, they make more than we do, deal with far less insurance issues, almost never deal with malpractice issues and can still easily survive solo. Pretty sweet.

 

[bedrock]

In my day all of the people who couldn't get into med school went into dentistry. So called "rejects". Now, they make more than we do, deal with far less insurance issues, almost never deal with malpractice issues and can still easily survive solo. Pretty sweet.

Yep. It’s now just as hard to get into dental school as Med school for those exact reasons.

Was very different 25 years ago when I was in college.

 

[Ferrismonk]

In my day all of the people who couldn't get into med school went into dentistry. So called "rejects". Now, they make more than we do, deal with far less insurance issues, almost never deal with malpractice issues and can still easily survive solo. Pretty sweet.

But... teeth.

 

[callmeanesthesia]

I'm gonna need more than N20. I hate going to the the dentist to begin with and now I going to use some local oral surgeon who I don't know. I will need lots of Xanax just to get through the door. It's a month wait to get in. In the interim, I'm applying a high concentration prescription fluoride gel to decrease the sensitivity.

I bought a few bottles of mepivacaine, chloroprocaine, and ropivacaine to test at the next available opportunity. Also going to test 2% lidocaine with bicarb.
If I were in your situation I’d definitely bring a bottle of whatever works and insist the surgeon uses it. I feel bad for my non-medical patients though because I know a lot of doctors and dentists wouldn’t believe them.

 

[TIVAndy]

just use cocaine. this local anesthetic always works great.

 

[BobBarker]

just use cocaine. this local anesthetic always works great.

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