Lidocaine doesn't work in an acidic environment

[thegenius]

I've heard this nonsense before and came across it again today. Had a PTA and cut the back of this throat and didn't get anything. I was frustrated and ENT kindly came in and literally aimed 1 mm caudal from my incision and took out 10 cc pus! So frustrated.

So I asked ENT why didn't you numb the back of the throat? She said it doesn't work because lidocaine doesn't anesthesize in acidic environments.

I mean this is nonsense! I anesthesize abscesses on external body parts all the time and pt's can't feel a thing. Why is this crap still disseminated?

(Nevertheless I was grateful that ENT came in to help me.)

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[RustedFox]

I've heard this nonsense before and came across it again today. Had a PTA and cut the back of this throat and didn't get anything. I was frustrated and ENT kindly came in and literally aimed 1 mm caudal from my incision and took out 10 cc pus! So frustrated.

So I asked ENT why didn't you numb the back of the throat? She said it doesn't work because lidocaine doesn't anesthesize in acidic environments.

I mean this is nonsense! I anesthesize abscesses on external body parts all the time and pt's can't feel a thing. Why is this crap still disseminated?

(Nevertheless I was grateful that ENT came in to help me.)

I've heard this repeated forever, but never bothered to:

1. Look it up to see if it was bogus, or...
2. Withhold local anesthesia with lidocaine.

You doing a ring block, or just injecting the abscess cavity itself?

 

[MechEDoc]

Lidocaine is an essentially neutrally charged, in an acidic environment, it picks up a positive charge and won't diffuse well across cell membranes.

 

[thegenius]

I've heard this repeated forever, but never bothered to:

1. Look it up to see if it was bogus, or...
2. Withhold local anesthesia with lidocaine.

You doing a ring block, or just injecting the abscess cavity itself?

I usually inject where I'm going to cut...and most of the time it's right over the abscess. It hurts during infiltration, but after waiting 2 minutes patients can't feel a thing as I cut, dig and irrigate around.

I have never injected lidocaine into anyone in any body tissue and not have it provide 100%, or near 100%, perfect local anesthesia.

 

[thegenius]

Lidocaine is an essentially neutrally charged, in an acidic environment, it picks up a positive charge and won't diffuse well across cell membranes.

I believe that chemistry...and I also believe that it provides anesthesia because it does every time I do it.

 

[Apollyon]

If you inject into the abscess, it won't do anything. But, the skin overlying is not acidic, and that is why I've always thought that the skin numbing works. I would show the pts, when I did lido with epi, the blanching ring, and tell them that that was where it was numbed.

 

[RuralEDDoc]

Valium must change the pH of an acidic environment. Because giving it 30-45 minutes before any procedure really seems to ease the pain associated with administration of both the local anesthetic and the following incision.

 

[turkeyjerky]

On my ortho rotation in residency, my senior made me drain a large hand abscess on a lady w/o any anesthesia at all. It was f'ing barbaric. And we literally had lidocaine right there, drawn up.

 

[Birdstrike]

I've heard this nonsense before and came across it again today. Had a PTA and cut the back of this throat and didn't get anything. I was frustrated and ENT kindly came in and literally aimed 1 mm caudal from my incision and took out 10 cc pus! So frustrated.

So I asked ENT why didn't you numb the back of the throat? She said it doesn't work because lidocaine doesn't anesthesize in acidic environments.

I mean this is nonsense! I anesthesize abscesses on external body parts all the time and pt's can't feel a thing. Why is this crap still disseminated?

(Nevertheless I was grateful that ENT came in to help me.)

The chemistry is irrelevant. It all comes down to whether you want 1 second of sharp pain from a scalpel or 1 second of sharp pain from a needle. But if you can't get the abscess open with a quick stab, then it's probably better to put some lidocaine in there. I think the "acidic environment" thing is old dogma that stemmed from the fact that its so painful to have lidocaine injected into an area overlying abscess, due to inflammation, a lot of people skipped the step. And it sounds a lot more scientific to spew out some smart sounding acid/base stuff which no one can disprove in real time, than to get patient to buy into, "It'll hurt less if we skip the numbing stuff and at least no worse," which never sells well, however true it may be.

This kind of dogma makes me laugh. Not because it's unproven dogma (we are forced to use it often). It's when its repeated by the same people that will question everything with a high-pitched, nasal, "You're wrong because you don't have a randomized, double bind controlled trial to prove that! And if you did it's probably not p e e r r e v u u u e w e d ." But they'll quote dogma like this all day long on the bet you won't demand they cite level 1 evidence for it, which they can't. They like to pick and choose the times when Level 1 evidence is needed and when it's not needed, based on what's most advantageous to them.

 

[Tenk]

Field blocks are your friend. Just do a block around the abscess. Works great and then you can really get in there and break up those nasty loculations.

 

[RoyBasch]

I usually think acidity slows the effect of lidocaine, but it still works. I find my anesthesia with abscesses is more effective when I give it 15-20 minutes prior incision and delocculation.

My technique for large legit abscesses (i.e. not overgrown zits or indurated cellulitis with minimal fluctuance, etc.).

see patient, order 1mcg/kg fentanyl IM

see another patient (15 mins)

come back to the abscess, inject small amount of lido right into the skin (not the cavity) over the point of maximum fluctuance, than use an 18ga syringe to aspirate out the abscess and flatten it. This takes pressure off the surrounding skin, which is turgid and I think now more painful to inject.

I then do a multi point field block around the abscess

see another patient (15 mins)

come back to the abscess and do the I&D.

This technique has some extra steps but patients tend to be much more comfortable.

 

[WilcoWorld]

I usually think acidity slows the effect of lidocaine, but it still works. I find my anesthesia with abscesses is more effective when I give it 15-20 minutes prior incision and delocculation.

My technique for large legit abscesses (i.e. not overgrown zits or indurated cellulitis with minimal fluctuance, etc.).

see patient, order 1mcg/kg fentanyl IM

see another patient (15 mins)

come back to the abscess, inject small amount of lido right into the skin (not the cavity) over the point of maximum fluctuance, than use an 18ga syringe to aspirate out the abscess and flatten it. This takes pressure off the surrounding skin, which is turgid and I think now more painful to inject.

I then do a multi point field block around the abscess

see another patient (15 mins)

come back to the abscess and do the I&D.

This technique has some extra steps but patients tend to be much more comfortable.

You ever run into trouble with that fentanyl dose on an unmonitored patient?

 

[RoyBasch]

You ever run into trouble with that fentanyl dose on an unmonitored patient?

I haven't yet, although I would say I do not use more than 100mcg even if the patient is larger, I kind of think of it as 1mcg/kg of IDEAL body weight (so the extra 100kg of fat doesn't buy you another 100mcg of fent).

If for some reason i was worried about the patient (elderly, frail, comorbidities with impaired metabolism, habitus concerning for restricted ventilation) I might put them on a pulse oximeter.

 

[Vandalia]

It is always interesting that the dogma is such that it minimizes the work needed by the person quoting it.

 

[Birdstrike]

It is always interesting that the dogma is such that it minimizes the work needed by the person quoting it.

Yes. The ENT doesn't have to wait for the "very busy" ED nurse to bring him a 10cc syringe and lidocaine on a silver platter.

 

[Rekt]

Lidocaine is pointless for a PTA. You shouldn't be doing any scalpel cutting. Benzocaine spray + needle aspiration.
Cutaneous abscess? Walk in with your supplies you got yourself and discharge paperwork. 10mL vague field anesthsizing and then say sorry this is going to hurt. Discharge.

 

[RustedFox]

Lidocaine is pointless for a PTA. You shouldn't be doing any scalpel cutting. Benzocaine spray + needle aspiration.
Cutaneous abscess? Walk in with your supplies you got yourself and discharge paperwork. 10mL vague field anesthsizing and then say sorry this is going to hurt. Discharge.

Am I you?
Are you me?

DID WE BREAK THE TIMELINE?!

 

[Brigade4Radiant]

In residency i mixed lidocaine with bicarb all the time lol. But that was because it supposedly decreases pain with injection

 

[thegenius]

You ever run into trouble with that fentanyl dose on an unmonitored patient?

Should be safe, 50-100 mcg IV is equivalent to 5-10 mg morphine. And this is given IM so absorption is delayed somewhat.

 

[thegenius]

In residency i mixed lidocaine with bicarb all the time lol. But that was because it supposedly decreases pain with injection

It does...and there are papers on that too.

 

[Angry Birds]

I usually think acidity slows the effect of lidocaine, but it still works. I find my anesthesia with abscesses is more effective when I give it 15-20 minutes prior incision and delocculation.

My technique for large legit abscesses (i.e. not overgrown zits or indurated cellulitis with minimal fluctuance, etc.).

see patient, order 1mcg/kg fentanyl IM

see another patient (15 mins)

come back to the abscess, inject small amount of lido right into the skin (not the cavity) over the point of maximum fluctuance, than use an 18ga syringe to aspirate out the abscess and flatten it. This takes pressure off the surrounding skin, which is turgid and I think now more painful to inject.

I then do a multi point field block around the abscess

see another patient (15 mins)

come back to the abscess and do the I&D.

This technique has some extra steps but patients tend to be much more comfortable.

Have you considered procedural sedation or GA?

 

[Miles Gloriosus]

In residency i mixed lidocaine with bicarb all the time lol. But that was because it supposedly decreases pain with injection

I do a lot of my procedures wide awake with lido with epi. The bicarbonate definitely helps with the burning sensation with injection.