Residents - try this to IMPRESS!

[epidural man]

It's called post-tetanic potentiation.

It's mentioned in some text books, but practically speaking, I haven't read a good description of it.

Anyway, this is the scenario, and what ya do.

Imagine you have a twitchless patient - and you don't have a clue when twitch number 1 is going to return (especially if you used that piece of **** drug rocuronium).

Then you say - holy crap, I'm going to use post-tetanic potentiation and know exactly when 1 twitch will return.

You then do hold tetany for 5 seconds (even though tetany is likely not to happen, you still hold the button down for 5 sec). You then turn on the 1 -sec twitch button - one twitch every second. Surprisingly, the patient will start to twitch every second. You then count how many twitches you feel before it fades and stops twitching.

If you count 10 twitches - you are a ways away from returning to 1 twitch. If you count 25 twitches, return of 1 twitch is just around the corner - 5 minutes or so.

Of course there is some variability to those numbers, but around 25 is when 1 twitch returns, in my experience.

Also, if you do the trick, you have to wait....i don't know...maybe 10 minutes? before repeating.

Try it...it's pretty cool - and reliable.

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[cfdavid]

It's called post-tetanic potentiation.

It's mentioned in some text books, but practically speaking, I haven't read a good description of it.

Anyway, this is the scenario, and what ya do.

Imagine you have a twitchless patient - and you don't have a clue when twitch number 1 is going to return (especially if you used that piece of **** drug rocuronium).

Then you say - holy crap, I'm going to use post-tetanic potentiation and know exactly when 1 twitch will return.

You then do hold tetany for 5 seconds (even though tetany is likely not to happen, you still hold the button down for 5 sec). You then turn on the 1 -sec twitch button - one twitch every second. Surprisingly, the patient will start to twitch every second. You then count how many twitches you feel before it fades and stops twitching.

If you count 10 twitches - you are a ways away from returning to 1 twitch. If you count 25 twitches, return of 1 twitch is just around the corner - 5 minutes or so.

Of course there is some variability to those numbers, but around 25 is when 1 twitch returns, in my experience.

Also, if you do the trick, you have to wait....i don't know...maybe 10 minutes? before repeating.

Try it...it's pretty cool - and reliable.

I most certainly will try it. Thanks.

 

[RussianJoo]

It's called post-tetanic potentiation.

It's mentioned in some text books, but practically speaking, I haven't read a good description of it.

Anyway, this is the scenario, and what ya do.

Imagine you have a twitchless patient - and you don't have a clue when twitch number 1 is going to return (especially if you used that piece of **** drug rocuronium).

Then you say - holy crap, I'm going to use post-tetanic potentiation and know exactly when 1 twitch will return.

You then do hold tetany for 5 seconds (even though tetany is likely not to happen, you still hold the button down for 5 sec). You then turn on the 1 -sec twitch button - one twitch every second. Surprisingly, the patient will start to twitch every second. You then count how many twitches you feel before it fades and stops twitching.

If you count 10 twitches - you are a ways away from returning to 1 twitch. If you count 25 twitches, return of 1 twitch is just around the corner - 5 minutes or so.

Of course there is some variability to those numbers, but around 25 is when 1 twitch returns, in my experience.

Also, if you do the trick, you have to wait....i don't know...maybe 10 minutes? before repeating.

Try it...it's pretty cool - and reliable.

What's the Hz for the tetany? 50Hz or 100Hz?

 

[Ketafol20]

I frequently use this to some degree. If then first post tetanic twitch is brisk then I don't bother counting the number of twitches. Twitches are not far off if the first post tetanic twitch is brisk. Especially if the first few area brisk. But if they are weak then you got some time to kill.

Epidural man, are you confident enough to reverse your pt who has no twitches but has post tetanic recruitment of around 20 twitches or a few real brisk ones?

 

[lord_jeebus]

Also, if you do the trick, you have to wait....i don't know...maybe 10 minutes? before repeating.

After testing post-tetanics, I move my stim leads to another nerve. I've heard 20-30 min but I would rather get my TOF elsewhere.

 

[epidural man]

I frequently use this to some degree. If then first post tetanic twitch is brisk then I don't bother counting the number of twitches. Twitches are not far off if the first post tetanic twitch is brisk. Especially if the first few area brisk. But if they are weak then you got some time to kill.

Epidural man, are you confident enough to reverse your pt who has no twitches but has post tetanic recruitment of around 20 twitches or a few real brisk ones?

Probably - if I were using nimbex. Not so sure with Roc, as it is so unpredictable. The slope of returning to twitches can be steep or very slanted. You?

After testing post-tetanics, I move my stim leads to another nerve. I've heard 20-30 min but I would rather get my TOF elsewhere.

I love this idea. thanks for the pointer.

 

[RxBoy]

(especially if you used that piece of **** drug rocuronium).

Man I hate roc. Its so unpredictable especially if given after sux induction or ESRD patients. The worst part is that even re administration for the SAME patient is unpredictable.

Once gave 10 for induction, 30 minutes later had 3 twitches... Gave 10 more, didn't have a twitch for an hour...

 

[proman]

Try it...it's pretty cool - and reliable.

I was showing a couple of CA1s this earlier. I use this all the time.

After testing post-tetanics, I move my stim leads to another nerve. I've heard 20-30 min but I would rather get my TOF elsewhere.

Waiting 6 minutes is likely long enough. I think Miller cited a paper that you shouldn't check TOF more frequently the q6 minutes for that reason.

 

[Ketafol20]

Probably - if I were using nimbex. Not so sure with Roc, as it is so unpredictable. The slope of returning to twitches can be steep or very slanted. You?

Yes, I will reverse them if I can recruit good twitches. I have been warned about the risks of re-paralyzation but honestly have never seen it. I use Roc exclusively.

 

[narcusprince]

Nothing wrong with giving 5mg of roc. Try just giving 1/2 cc to 1/4 cc and see the response!

 

[pgg]

I've reversed PT twitches with vec and cis without trouble a number of times (though it's not what I plan for obviously). I got burnt with roc once, probably shouldn't have extubated that patient but was dumb. Classic floppy fish action, spent another 20 min in the OR wishing I hadn't tried.

 

[epidural man]

Yes, I will reverse them if I can recruit good twitches. I have been warned about the risks of re-paralyzation but honestly have never seen it. I use Roc exclusively.

you should try nimbex...

I'll bet you a dollar you like it.

 

[btbam]

I feel like I was taught that >10 post-tetanic was ~1 twitch, but yes it's a cool and useful tool.

 

[epidural man]

I feel like I was taught that >10 post-tetanic was ~1 twitch, but yes it's a cool and useful tool.

I was too, but it never works. For me it always seems to go about 20+ twitches before the first twitch comes back.

 

[narcusprince]

To quote longnecker if you can get four twitches from sustained tetanus when paralyzing with rock it correlates with 15 minutes before recovery of one twitch. For Pancuronium its roughly 30 minutes. A lot of errors when it comes to reversal is contingent on good communication between the surgeon and anesthesiologist. Understanding that relaxed conditions do not necessitate muscle relaxants. Also, try using drugs with muscle relaxant like properties like remifentanyl ever intubate on bolus remi? One good thing about the neostigmine shortage is it refined my skills of providing a relaxed environment without using muscle relaxants.

 

[Ketafol20]

you should try nimbex...

I'll bet you a dollar you like it.

Nimbex is a fairly good drug as well. I've used it many times. It is easy to reverse but it requires more dosing intervals. I don't really care which paralytic I use actually. They all work fine.

 

[WholeLottaGame7]

To quote longnecker if you can get four twitches from sustained tetanus when paralyzing with rock it correlates with 15 minutes before recovery of one twitch. For Pancuronium its roughly 30 minutes. A lot of errors when it comes to reversal is contingent on good communication between the surgeon and anesthesiologist. Understanding that relaxed conditions do not necessitate muscle relaxants. Also, try using drugs with muscle relaxant like properties like remifentanyl ever intubate on bolus remi? One good thing about the neostigmine shortage is it refined my skills of providing a relaxed environment without using muscle relaxants.

I'm on ENT this month, so not using a lot of muscle relaxant in general. I'm getting a lot of practice keeping someone relaxed using volatile, remi infusion, remi/propofol boluses prn.

Obviously the best way to plan paralytic dosing is good communication, but if I have any doubts towards the end of the case, I'd definitely rather use alternative methods to keep someone down.

 

[goosegas]

Man I hate roc. Its so unpredictable especially if given after sux induction or ESRD patients. The worst part is that even re administration for the SAME patient is unpredictable.

Once gave 10 for induction, 30 minutes later had 3 twitches... Gave 10 more, didn't have a twitch for an hour...

I occasionally hear people complain about Roc and I am always puzzled. It has been my NMB of choice for over 10 years and I don't think I have ever been burned by it. When you say you gave "10", you mean 10mg, not 10ml correct?

 

[ssmallz]

I occasionally hear people complain about Roc and I am always puzzled. It has been my NMB of choice for over 10 years and I don't think I have ever been burned by it. When you say you gave "10", you mean 10mg, not 10ml correct?

I agree. I used it almost exclusively in my residency and I've only been burned once and that was my own fault for dosing it too far to the end. Outside of that, I've really never had an issue

 

[W222]

I occasionally hear people complain about Roc and I am always puzzled. It has been my NMB of choice for over 10 years and I don't think I have ever been burned by it. When you say you gave "10", you mean 10mg, not 10ml correct?

Completely agree here, its my "go-to" paralytic. I have heard others complain that it is sketchy at times, sometime not working at all and other times working far too long. I feel that this has to do with storage and if it has been out of the fridge for a while it loses its effectiveness. Have only been burned by rocuronium once and that was due to inadvertant subQ administration when an IV infiltrated, guy became floppy in PACU and had to be reintubated.

Nimbex is a great drug, I like an infusion set to 1-2 twitches for longer cases and TIVA.

One question I am still trying to figure out with nimbex, do you need to reverse it? Some attendings argue staunchly no while others say you do.

 

[Ketafol20]

You only need to reverse it if there is still some of it working. Just like every other NMB. If they have had all 4 twitches without any fade for some time then no need to reverse. I know this is contrary to ASA rec's but we are physicians not nurses. We can evaluate our pts can't we?

 

[RussianJoo]

You only need to reverse it if there is still some of it working. Just like every other NMB. If they have had all 4 twitches without any fade for some time then no need to reverse. I know this is contrary to ASA rec's but we are physicians not nurses. We can evaluate our pts can't we?

I don't know, i get a lot of my pt's breathing towards the end of the case with 4 strong twitches, without reversal, they usually pull >200ml Tv consistently, after reversal they start pulling ~450ml Tv's.

 

[proman]

You only need to reverse it if there is still some of it working. Just like every other NMB. If they have had all 4 twitches without any fade for some time then no need to reverse. I know this is contrary to ASA rec's but we are physicians not nurses. We can evaluate our pts can't we?

Just because a paralytic undergoes non-enzymatic degradation doesn't mean it won't cause residual paralysis. There is such little downside to reversing. The only time I won't necessarily reverse is if it's been 5 half-lives since the last dose.

 

[btbam]

You only need to reverse it if there is still some of it working. Just like every other NMB. If they have had all 4 twitches without any fade for some time then no need to reverse. I know this is contrary to ASA rec's but we are physicians not nurses. We can evaluate our pts can't we?

4 twitches with no fade = up to 50% of receptors still blocked, unless they are pulling 350+ tidal volumes I'm giving 1+0.2

 

[Ketafol20]

Fair enough everyone. I'll leave this subject alone. In no way am i telling you we shouldn't be reversing our pts. All I meant was that this cookbook way of treating everyone isn't always appropriate.

 

[fakin' the funk]

We can evaluate our pts can't we?

Evaluate all you want, but you still can't tell the difference between a TOF of 0.5 and 0.9.

 

[fakin' the funk]

It's called post-tetanic potentiation.

I do this all the time.* I view it as a basic part of neuromuscular monitoring. It's well described in Miller and Barash.

* (when I hose myself with NMB and get the patient to 0/4 twitches)

 

[beavis]

I do this all the time.* I view it as a basic part of neuromuscular monitoring. It's well described in Miller and Barash.

* (when I hose myself with NMB and get the patient to 0/4 twitches)

And you start thinking..."I hope they let the intern close..."

 

[lord_jeebus]

And you start thinking..."I hope they let the intern close..."

And then, horror of horrors, the sound of a stapler

 

[btbam]

And then, horror of horrors, the sound of a stapler