nmb dosing?

[heathermed]

hello everyone...

I was hoping for some help. I'm a new CA 1 and am struggling with NMB dosing. We mainly use Roc and Vec.

The issue I am having is that I consistently am paranoid about checking twitches and am not confident if i gave enough or too little. I mainly want to be able to have a dosing regimen and not have to be worried about checking twitches every 5 mins.

Does anyone have a "system" that seems to work in your experience?

thanks for your help!

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[Bertelman]

Follow the recommended dosing. 1 cc vec per 10 kg weight.

You should be paranoid, and you should be checking twitches frequently. Thats what CA1s do. You will figure out when to underdose, like for really old people and really quick cases, through your own experience. I would challenge you to see how little you can get away with. Don't feel like you have to keep pushing NMB to maintain a single twitch. Most cases you can coast through with just the induction dose, maybe a little more before they close peritoneum.

 

[RxBoy]

Its cause its early in your career. You'll eventually get better at it without having to check all the time. I check and dose maybe once every 30 min. I avoid 0 or 4 twitches. I like 1 strong twitch throughout the case.

I keep them pretty paralyzed all the way up to extubation because I blow off all my gas before I reverse. I shoot for 3 twitches before I reverse. Most people do the opposite, get them breathing and then shut off the gas.

So its really dependent on the case and your extubation strategy, but either way you'll get better with experience. The only advice I can give you is NEVER reverse zero (or one really weak) twitch, you will get burned. Had to put a lot pts on PACU vents due to CA1 july antics.

 

[jwk]

hello everyone...

I was hoping for some help. I'm a new CA 1 and am struggling with NMB dosing. We mainly use Roc and Vec.

The issue I am having is that I consistently am paranoid about checking twitches and am not confident if i gave enough or too little. I mainly want to be able to have a dosing regimen and not have to be worried about checking twitches every 5 mins.

Does anyone have a "system" that seems to work in your experience?

thanks for your help!

I'm a heathen - I generally don't check twitches intra-op at all (I guess that's not a great residency answer though). If the surgeon thinks they're getting tight, I might think about it, but since I use mainly Roc, I'm not going to get burned giving 10mg even late in the case.

Experience and familiarity with your surgeons will be the key here, and you're not at that point yet. When I was in training 30+ years ago, I routinely gave 5-7mg of pancuronium to open gallbladders, of course waiting until they recovered from their intubating dose of sux to wear off which was the custom at the time (no twitch monitors back then). Of course those cases routinely took 4 hours. Then I went to a private practice rotation - the sux was gone about the time the incision was made, so I gave 7mg of panc. Less than 20 minutes later, the surgeon was done. "Duh, duh, duh, uh, they're not going to breathe for a while" says the embarassed student (me). Lesson learned very quickly. Know your surgeon.

 

[pgg]

Rule #1: You need less relaxation than you think you do as a new CA1, and a lot less than the surgeons think they need.


If you're using a nondepolarizer for intubation, give it time to work. You don't need 0.6 mg/kg of roc to intubate an easy looking airway. Consider giving a priming dose of 10 mg before you induce. Mask ventilate the patient for 30 seconds or a minute. Someone will surely chime in here and say their goal is an intubated patient turned over to the nurse to prep in 3.6 minutes from door time and waiting 45 seconds for the roc to work is wasteful ... bah, you can take your time with induction and still be efficient.


It's easy to give more relaxant. It's hard to burn yourself by giving 1-2 mg of vec at a time or 10 mg of roc at a time, if you wait a few minutes and check twitches again. Give it time to work, and don't let a surgeon glare you into hurrying or giving another dose too soon.


If despite the above you find yourself stuck with a flat patient and no more surgery to do, like RxBoy says, don't try reversing patients with 0 twitches. Just wait. Sometimes reversal will work, but usually you're just buying yourself a floppy fish patient or worse, a reintubation. The exception to that rule is if you have post-tetanic twitches with vecuronium, they're probably reversible. I don't play that post-tetanic game with rocuronium ... but I've found that vec is both more predictable and forgiving.

 

[Oggg]

Many surgeries don't require full paralysis, so don't redose unless you need it. Keep the patient deep with narcs/gas and hyperventilation to keep them from breathing

1-3 twitches usually means they're plenty relaxed (unless youre twitcher or twitch location is messed up). So when the surgeon says the patient is too tight:
1. First, confirm that the pt has only 1-3 twitches and they're not about to start bucking or breathing.
2. Depending on your relationship with the surgeon,
A) tell them the pt IS relaxed
B) lie and tell them you just gave them some more vec
C) consider increasing the gas or giving PPF

You'll find out what surgeons are idiots (I have an experienced surgeon who says "I can't close this appy unless you relax her some more, I don't care if she needs a ventilator postop"), and the lying comes easier when you know you're doing what's best for the patient AND the surgeon.

 

[Idiopathic]

rule A number 1 in all of medicine: you can always give more (unless its during ACLS, then you give it all).

 

[codeb1ue]

I too am a new CA-1 and was very confused about the specific use of NMBs.

Outside the initial use to facilitate intubation, is the main/only need to re-dose and maintain paralysis to keep the pt flaccid for operative ease? (e.g. preventing surgeon from fighting a tightened muscle). I used to think it was to prevent the patient from breathing, bucking the vent, or moving during the surgery but I am now realizing the anesthetics should be serving those purposes and not the NMBs. Am I correct in this? Sorry for the basic anesthesia 101 type questions.

 

[RxBoy]

Outside the initial use to facilitate intubation, is the main/only need to re-dose and maintain paralysis to keep the pt flaccid for operative ease?

You will soon realize a very important principle in anesthesia. It takes very little anesthesia to keep someone in the sedative/hypnotic state and even less for amnestic states. However it takes far more anesthesia to keep someone from moving (MAC1).

Paralytics add to the concept of balanced anesthesia. You can give far less potent anesthetics with paralytics to achieve the same surgical conditions as you would with heavy dose anesthetics alone. You don't have to give industrial doses of anesthetics to keep the pt from moving. Either way the patient will not be aware of the surgery, and even if they are, there is almost a zero chance they will remember it.

When the patient is relaxed (whether with paralytics or high dose volatile anesthetics), it makes muscle tissue manipulation much easier. Think about the extra force used intubating a pt without muscle relaxants, this is similar to what the surgeon experiences with the muscle fibers at the surgical site.

Your goal as anesthesiologist will be to balance all the medications so that you can minimize dangerous side effects to the patient while facilitating conditions for the surgeon. Paralytics make it much it much easier to achieve these goals.

So to answer you question, paralytics are used for both good anesthetic and surgical conditions. They're not necessary, but immensely helpful.

 

[jwk]

So to answer you question, paralytics are used for both good anesthetic and surgical conditions. They're not necessary, but immensely helpful.

An important concept to remember - anesthesia makes surgery possible, not easy. The corollary to this is "movement doesn't imply wakefulness", especially when the surgeon just bovied a nerve. It's a shame most surgeons don't recognize these simple concepts.

 

[Ignatius J]

One thing I've seen done lately and works great. If the case goes over 2 hours, use your induction dose of Vec as a loading dose than hit 'run' on a preset Vec drip. Keeps 'em at 1 twitch throughout the case and you don't have to worry about constantly redosing and checking and being paranoid about it all.

I've done this for those marathon breast free flaps and love it.

 

[BobBarker]

I would only drip nimbex.

 

[Ignatius J]

I would only drip nimbex.

Why?

 

[BobBarker]

More reliable to predict. Non steroid based.

 

[fakin' the funk]

More reliable to predict. Non steroid based.

That's why you don't predict. You titrate to TOF.

What am I missing about the relevance of vec's steroid base?

 

[fakin' the funk]

One thing I've seen done lately and works great. If the case goes over 2 hours, use your induction dose of Vec as a loading dose than hit 'run' on a preset Vec drip. Keeps 'em at 1 twitch throughout the case and you don't have to worry about constantly redosing and checking and being paranoid about it all.

I like vec drips for such cases also. Long belly cases, long neuro cases, etc. The dose usually ends up being between 2-4mg/hr. I put 20mg in a 100ml bag. Titrate to 1-3 twitches. Saves a lot of rebolusing and on/off effect you get with boluses.

 

[fakin' the funk]

The issue I am having is that I consistently am paranoid about checking twitches and am not confident if i gave enough or too little. I mainly want to be able to have a dosing regimen and not have to be worried about checking twitches every 5 mins.

1. No one needs all twitches abolished. This should only happen after a 2xED95 dose. Edit: sometimes if you are monitoring the facial nerve and the surgeon is working on the belly you may have 0-1 twitches but they still feel tight or the diaphragm+liver are moving. Follow the advice above on length of surgery, reliability/skill of surgeon, etc.

2. Not all NMB's are created equal. When I started residency I was taught "1ml per 10kg to start, 1ml for maintenance." But that simply isn't true. Roc's ED95 is 0.3mg/kg and comes in 10mg/ml. But Vec's ED95 is 20% that (0.06mg/kg) and comes at only 10% that (1mg/ml). Therefore, roc, ml for ml, is 2x as "strong" as vec.

3. Beware roc. Large doses, redosing, keeping people 1 twitch, etc., it just anecdotally is harder to reverse. Maybe it's all those damn molecules -- 10x as many as panc and vec for the same effect.

 

[Arch Guillotti]

What am I missing about the relevance of vec's steroid base?

I don't get it either.

 

[BobBarker]

Infusion of steroid based paralytics increases likelihood of myopathy. Our free flaps run 20 hours frequently and then we take them to PACU breathing on flowby through their trach. I think that amount of time and exposure would have a chance of doing it. Do you guys ever see vec drips in the ICU?

 

[Ignatius J]

Infusion of steroid based paralytics increases likelihood of myopathy. Our free flaps run 20 hours frequently and then we take them to PACU breathing on flowby through their trach. I think that amount of time and exposure would have a chance of doing it. Do you guys ever see vec drips in the ICU?

I've seen vecuronium drips in our ICU. In just a quick look at the topic, it appears that whether one classification of NMBAs has an increased risk relative to the other in myopathy is debatable. And remember, these studies are based on ICU patients that probably didn't have neuromuscular monitoring (I'm guessing). I've done it with our 20+ hour flaps (good to know my institution isn't the only one that has flaps this long!) and extubated at the end without a problem. Not a large sample size, and good ideas, but I wouldn't avoid a steroid based paralytic infusion with hazy evidence.

My reasoning- Nimbex is more expensive than Vec to run an infusion with.

 

[fakin' the funk]

Infusion of steroid based paralytics increases likelihood of myopathy. Our free flaps run 20 hours frequently and then we take them to PACU breathing on flowby through their trach. I think that amount of time and exposure would have a chance of doing it. Do you guys ever see vec drips in the ICU?

a) Yes we do see vec drips. Not as common as cis but still used.
b) I was under the impression that critical illness polyneuropathy is more about high-dose steroids than anything else.
c) Intensivists are unbelievably afraid of NMB infusions anyway. Someone basically needs to code from hypoxemia before they'll consider using them to decease VO2 and improve vent synchrony.

 

[BobBarker]

This was the best article I could find while quickly searching.
http://www.anesthesia-analgesia.org/content/81/1/3

But the issue is more ambiguous than I have been lead to believe. With our flaps, I can turn the cis off at closure and reliably not have to reverse. Most of the time I don't do the drip or keep them paralyzed after 10pm, however!

 

[HollywdAnesth]

Our free flaps run 20 hours frequently and then we take them to PACU breathing on flowby through their trach.

Why do you need muscle relaxation for a free flap?

 

[BobBarker]

I don't. I take over cases on call regularly where someone thinks they do. Sometimes I just let their infusion keep going.

 

[Mman]

Paralytics add to the concept of balanced anesthesia. You can give far less potent anesthetics with paralytics to achieve the same surgical conditions as you would with heavy dose anesthetics alone. You don't have to give industrial doses of anesthetics to keep the pt from moving. Either way the patient will not be aware of the surgery, and even if they are, there is almost a zero chance they will remember it.

When the patient is relaxed (whether with paralytics or high dose volatile anesthetics), it makes muscle tissue manipulation much easier. Think about the extra force used intubating a pt without muscle relaxants, this is similar to what the surgeon experiences with the muscle fibers at the surgical site.

Your goal as anesthesiologist will be to balance all the medications so that you can minimize dangerous side effects to the patient while facilitating conditions for the surgeon. Paralytics make it much it much easier to achieve these goals.

So to answer you question, paralytics are used for both good anesthetic and surgical conditions. They're not necessary, but immensely helpful.

Also keep in mind that the larger the dose of paralytic you are using, the higher the chance for postop respiratory problems. I don't care what you think your TOF says when you are reversing, giving less NMB overall leads to less postop reintubation. It's a rare problem to start with, but we are in the business of safety and having 1 fewer reintubation per 1000 cases adds up in the longterm.

NMBs are to facilitate intubation. Beyond that you can provide adequate surgical conditions in many different ways. Some surgeries require more NMB than others.