Rebound Pain after Nerve Blocks - Prevention & Management (Part 2)

An update on rebound pain and the evidence for possible strategies for prevention and management, as presented at the Annual ESRA Congress in June 2022.

[@tweedmonster]

Really excellent presentation. Thank-you so much. It will definitely change my practice.

[@danieluhlmann7215]

Brilliant!

[@jean-marieparlanti4086]

presentation always so practical and intelligent. but what do you think of the crystallization of ropivacaine when combining adjuvants?

[@KiJinnChin]

I must admit I have not observed visible crystallization and also unaware of reports that this could occur. Do you have any literature on this?

[@jean-marieparlanti4086]

@@KiJinnChin Regional Anesthesia and Pain Medicine. 2022 Jun 23;
Crystallization of ropivacaine and bupivacaine when mixed with different adjuvants: a semiquantitative light microscopy analysis.

[@nerveblock]

Hi Dr Chin, awesome teaching as always. Are you using / have you used dexmed as well? It's my standard now for when I want to prolong duration of blocks. Typically using less than most of the studies used, certainly well below 1mcg/kg - typically between 20-40mcg total for an average adult. I'll combine this with either perineural or IV dexamethasone depending which way the wind is blowing that day. It's now cheap in Australia ~$7 a 200mcg vial - which you can get at least 4 blocks out of. Just wondering on your experience with it as i've found it quite remarkable how long a C5/6 or superior trunk can last for scopes. Anecdotally seeing very little rebound (underlying?) pain, though yet to see a study with the combination. Cheers - michael

[@KiJinnChin]

Fantastic comments and info. Dexmed is still very expensive in Canada so I have used it only occasionally. I did hear at ESRA about this combination or versions of it and definitely worth exploring. Good to know that lower doses are effective- one always worries about the possible hemodynamic effects. And I love the “depending which way the wind is blowing” comment - I too often let that guide my specific choices 😅

[@nerveblock]

@@KiJinnChin just wanting to thank you for taking the time to reply. Hopefully meet you one day at asra or esra. Cheers

[@erickim1830]

@@KiJinnChin Dr Chin, do you have any thoughts on using multiple perineurial adjuvants simultaneously? One of my surgeons has asked for concomitant perineurial decadron and precedex. Adductors prolonged to 2 days; but I've noticed some prolonged block duration (>7 days) perhaps 3-5% of the time.

[@KiJinnChin]

@@erickim1830 I have no personal experience as dexmedetomidine remains expensive here in Canada. But am hearing more and more anecdotal reports from practitioners such as @mick kerr and @uramalakia that the combination does appear to prolong some PNBs more than just one agent alone. Systematic studies would be needed to know how consistent this effect is. Your observations of >7d probably represent the tail of the distribution of responses, and would be consistent with the general principle of biological variability. There will be an opposite tail, in which we see underwhelming results in a small percentage of subjects.

[@uramalakia]

​​​@@KiJinnChinHere, here. Note: Adding dexmedetomidine "cancels out" the smoothing effect of dexamethasone on the process of block cessation it would seem. When adding both, the duration is significantly increased but the cessation is now abrupt. My patients would say it feels like someone flipped a pain switch in their operated extremity, going from absolutely no pain to moderate to intense pain.
My exploration of the dex-dex combo has led me to the conlusion that anything beyond 1,25mcg of dexmedetomidine per mL of analgetic mixture is unneccessary - the effect on block duration is most pronounced by adding it. By upping the dose, the benefits are much less while the frequency of side effects, such as bradycardia, become more pronounced.
My quest continues. 😂

[@tl854393]

Can we use the normal type of IV-use-dexamethasone for adding to LA? We dont have reserve free dexa.

[@KiJinnChin]

I cannot recommend that, due to presence of preservatives which have unknown potential neurotoxic effects on the nerves. If this is all you have, I suggest that you just administer the dose IV close to the time of block performance.

[@jean-marieparlanti4086]

presentation always so practical and intelligent. but what do you think of the crystallization of ropivacaine when combining adjuvants?

[@nerveblock]

I've never seen it, unless you're using bicarb

[@uramalakia]

​​​@@nerveblockIt's not visible by naked eye, since the crystalls that form are microscopic. It is my understanding that it is the pH difference between ropivacaine and the most coomon adjuvants, such as dexamethasone, that causes the crystalls to form. There is no studies to quantify the clinical relevance of this as of now. I can only report that I've had no problems in my clinical practice whatsoever on this front in the 3 years since I started using adjuvants with ropivacaine myself. Hope this helps.