Preservative free local anesthetic for peripheral nerve blocks

[sleepallday]

I have always used preservative free local anesthetic for all my peripheral nerve blocks. However, lately outside factors have been trying to persuade me to use non-preservative free local anesthetic because of the price. I was told that it doesn't make a difference but I'm not buying it and have continued to use PF.

What are the thoughts of some of you on this?

I should add that all my blocks are done with the ultrasound and local injected intraneurally but NOT intrafascicularly.

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[sleepallday]

Nobody?

 

[deleted9493]

For a peripheral nerve block, I can't say that I'd have a problem using whatever local anesthetic is available and appropriate for the case at hand...whether preservative-free or not. That is, assuming that the patient has no allergies. Of relatively greater importance in my mind is using good technique that mitigates the likelihood of infection and/or failure (inadequate for procedure; unsatisfactory duration).

Preservatives have been associated with negative side effects in neuraxial anesthetics but I am not aware of side effects using local anesthetics with preservatives for peripheral nerve blocks. I certainly welcome any education on this topic if it is out there...

 

[drccw]

Don't do it...
If, and I know that this is a big if but still, anything happens you're hosed....

Look what happened with the NECC when places tried to cheap out... Bad bad stuff... Arguably nothing that bad should happen but still- what if you have a case of nerve damage......

drccw

 

[stonemd]

I use preservative free for all PNBs - locals and dexamethasone. Why add an unescessary drug that has some potential neurotoxicity?
BTW what do you mean intraneural but not intrafasicular? Can you see all the fascicles in the nerves and avoid penetrating them? I have good success rates injecting around the nerves. I like to use the US to keep my injection away from penetrating any nerves.

 

[pgg]

I also use PF local. For a while we didn't have PF dexamethasone, so I stopped adding it to my blocks. I don't believe for a second that tiny amount of preservative would make a difference, but if a patient ever winds up with any deficit, whether it's from direct surgical trauma, positioning, whatever, I don't want to have to explain why I injected benzyl alcohol into the plaintiff's nerve. However small a volume.

 

[deleted9493]

In terms of neurotoxicity, local anesthetics are 'neurotoxic' (causing reversible neural edema on microscopy) whereas metabisulfite and methlyparaben do not appear to be in animal neuronal exposures. These preservatives have been used for ages in the dental world with a good safety track. A known sensitivity to PABA or the desire to eliminate the possibility of a hypersensitivity reaction to PABA would both be justifiable rationales to use preservative-free solutions.

Intraneural injection of local anesthetic is far less defensible than using preservative containing local for a peripheral nerve block.

 

[sleepallday]

I use preservative free for all PNBs - locals and dexamethasone. Why add an unescessary drug that has some potential neurotoxicity?
BTW what do you mean intraneural but not intrafasicular? Can you see all the fascicles in the nerves and avoid penetrating them? I have good success rates injecting around the nerves. I like to use the US to keep my injection away from penetrating any nerves.

I inject intraneural meaning just within the nerve sheath and hence the doughnut formation. If one were to inject intrafascicular, you would then see the nerve fascicles spread apart and this is what can potentially cause nerve injury.

 

[sleepallday]

In terms of neurotoxicity, local anesthetics are 'neurotoxic' (causing reversible neural edema on microscopy) whereas metabisulfite and methlyparaben do not appear to be in animal neuronal exposures. These preservatives have been used for ages in the dental world with a good safety track. A known sensitivity to PABA or the desire to eliminate the possibility of a hypersensitivity reaction to PABA would both be justifiable rationales to use preservative-free solutions.

Intraneural injection of local anesthetic is far less defensible than using preservative containing local for a peripheral nerve block.

To say that you must avoid intraneural injection is incorrect. Injecting within the nerve sheath is considered intraneural. Like I said above, intrafascicular injection is what can cause possible injury.

 

[deleted9493]

To say that you must avoid intraneural injection is incorrect. Injecting within the nerve sheath is considered intraneural. Like I said above, intrafascicular injection is what can cause possible injury.

True that most intraneural injections are fine and not associated with nerve injury. That said, the studies that address this matter advise against intraneural injection. You could say, "Well, I use a blunt needle and don't inject at high pressures or with paresthesias." Great. I was just making the point that when you're talking about 'defensibility' of a clinical practice, if there is literature that advises against your practice, you should probably have good justification for your practice or abandon it.