Awareness without NMBs

[NewtownD]

---

Members do not see this ad.

I am in my first year of anaesthesia training in Ireland. Quick question that I thought had a straightforward answer, but different bosses keep telling me different things:

Can a patient having a GA without a neuromuscular blocker have awareness intra-operatively?

Example: a young healthy woman having a wrist operation with an LMA, an etSev of 1.8 (ie less than 1MAC), standard induction with fentanyl and propofol and a bit of morphine pre-incision. Breathing spontaneously RR 14, no hypertension/tachycardia.

Can someone like this be aware? My understanding was that long before someone like this becomes aware, they will laryngospasm or start moving.

Cheers,

D

 

[Idiopathic]

Things that are possible versus things that are likely. Of course it CAN happen. You can predict things that would clue you in to possible intraoperative awareness, such as tachycardia, hypertension, movement, etc, but you cant completely rely on them.

Also, a patient could be aware, but not uncomfortable. Again, unlikely, but possible.

 

[NewtownD]

Thanks for the reply. This is the answer I have received from some of my bosses.

Others have contradicted this, and said: awareness only happens when NMBs are used. It cannot happen in the above-mentioned patient, because before they are aware they move in response to pain or laryngospasm.

Therefore, you can reassure patients who are anxious about awareness that "we are planning to use the kind of anaesthesia where awareness can't happen".

 

[Consigliere]

Ask the good folks at Aspect and they'll tell you their BIS monitor can prevent awareness. 🙄

 

[Idiopathic]

Thanks for the reply. This is the answer I have received from some of my bosses.

Others have contradicted this, and said: awareness only happens when NMBs are used. It cannot happen in the above-mentioned patient, because before they are aware they move in response to pain or laryngospasm.

Therefore, you can reassure patients who are anxious about awareness that "we are planning to use the kind of anaesthesia where awareness can't happen".

I promise people in whom I plan on using volatile anesthesia that I guarantee they will not wake up during surgery, but I would never promise them that it couldnt happen, and I dont think you should either.

Analagous to a MAC case, where patients may be aware but shouldnt be uncomfortable...again, you may not move or show objective signs of awareness but could still possibly be completely aware, so you need to rely on things like end tidal volatile or even *gasp* a BIS monitor for TIVA.

In my experience, intraoperative awareness outside of the high risk groups (cardiac surgery, stat OB, level 1 traumas) is ALWAYS due to operator/setup issues (vaporizer error, not filled/run dry, not turned on, paralytic before sedative, prolonged airway. I think the literature is supportive of this as well. Its so uncommon in the general population that if you maintain a decent end tidal volatile and dont make egregious errors then you should have a case. (just personal opinion).

 

[Mman]

I promise people in whom I plan on using volatile anesthesia that I guarantee they will not wake up during surgery, but I would never promise them that it couldnt happen, and I dont think you should either.

I prefer not to make any guarantees. I let patient's know that my first concern is their safety and my second concern is that they are comfortable (comfortably asleep in the OR and comfortably free of major pain in the PACU). If they ask about awareness, I assure them that while it is possible they are not in a high risk group (unless they are) and that assuming they are safe I will do everything I can to make sure they are asleep.

 

[pgg]

How many of you routinely mention awareness during your consent talk? (I don't talk about it unless they ask.)

 

[Narcotized]

I promise people in whom I plan on using volatile anesthesia that I guarantee they will not wake up during surgery, but I would never promise them that it couldnt happen.

"I won't promise waking up can't happen, but I promise it won't happen to you." 🙂

 

[Idiopathic]

How many of you routinely mention awareness during your consent talk? (I don't talk about it unless they ask.)

I talk about it every time.

 

[chfo]

How many of you routinely mention awareness during your consent talk? (I don't talk about it unless they ask.)

INFORMED consent! 😱

That doesn't stop the lawyers though. 🙄

 

[Arch Guillotti]

I talk about it every time.

Huh, I never mention it unless the pt. specifically asks. I don't see the utility of discussing such an unlikely risk.

 

[proman]

I approach it like Mman does
1) safe
2) comfortable
3) asleep (I spent more time on the post-op intubation so that the family knows it's expected).
For patients who I expect to extubate in the OR, I mention they might remember that part.

As for the original question, yes awareness is possible without NMB but much less common. And, short of continuous isoelectric EEG, there's no way to guarentee lack of awareness.

 

[Idiopathic]

Huh, I never mention it unless the pt. specifically asks. I don't see the utility of discussing such an unlikely risk.

its something that nearly every patient is worried about, in my opinion.

 

[Bertelman]

Therefore, you can reassure patients who are anxious about awareness that "we are planning to use the kind of anaesthesia where awareness can't happen".

I wouldn't make that claim. It only sets them up to ask the same ridiculous question for their next anesthetic.

"Doctor, are YOU going to use the magic anesthesia that GUARANTEES I won't be aware? The last fellow did that, and now he's my favorite anesthesiologist. His name is Dr. Newtown. Is he available?"

I guarantee I will hunt you down, and ask you what exactly you told this crazy lady that makes her think you have some magic anesthetic that guarantees no awareness. Making that statement will set them up to believe there are two kinds of anesthesia: One that guarantees no awareness, and another that permits it. That's just wrong.

 

[pgg]

its something that nearly every patient is worried about, in my opinion.

I don't know if I agree. I think I do a pretty thorough consent spiel, and I always ask the patient if they have any questions or concerns about anything. They almost never ask about awareness. I don't think they're intimidated or embarrassed, but who knows.

Any time I do MAC case I'm very specific about the possibility of recall, and that recall under those circumstances is common and normal as the intent isn't GA. For GA I always talk about emergence and the possibility that they might remember the ETT being removed as they wake up.

Most patients seem satisfied and reassured when I tell them that my job is to keep them safe and comfortable, that anesthesia is very safe but that nothing is ever zero risk. Awareness is an enumerated risk on our consent forms - they all read it (sort of) but people rarely ask.

INFORMED consent! 😱

That doesn't stop the lawyers though. 🙄

Actual recall, outside of high risk cases or MACs, is rare. Actual harm from such an event is rarer still.

I use the words "organ damage and death" when talking to every single patient; I don't specifically mention which organ might be damaged how, there are just too many things that might go wrong. For selected cases when I talk about the possibility of postop ventilation, I don't bring up VAP or trachs.


Anyway, I asked in this thread because I was curious how others view it and I'm always trying to re-examine what I do to see if I should change.

 

[pgg]

Therefore, you can reassure patients who are anxious about awareness that "we are planning to use the kind of anaesthesia where awareness can't happen".

I'm with Bertelman; I think it's a really bad idea to offer guarantees.

 

[sevoflurane]

I am in my first year of anaesthesia training in Ireland. Quick question that I thought had a straightforward answer, but different bosses keep telling me different things:

Can a patient having a GA without a neuromuscular blocker have awareness intra-operatively?

Example: a young healthy woman having a wrist operation with an LMA, an etSev of 1.8 (ie less than 1MAC), standard induction with fentanyl and propofol and a bit of morphine pre-incision. Breathing spontaneously RR 14, no hypertension/tachycardia.

Can someone like this be aware? My understanding was that long before someone like this becomes aware, they will laryngospasm or start moving.

Cheers,

D

Awareness can happen in any case that goes south. B.P in the toilet and pressors not giving you the rise you are looking for? Volatile is one of the first things that gets dialed down and in extreme cases turned off +/- IV scopolamine.

How likely is awareness when the B.P. is in the 40-50's (decreased CBF)? Not likely with residual anesthetics on board, but very possible. Cardiac, Trauma and OB are notorious for recall regardless of weather you use NMB or not.

"Awareness" in the eye of the patient may mean waking up with an ETT in the trachea as they emerge through the stages of anesthesia. This is not what I call being "aware" during a case. It's just waking up from anesthesia. It's a normal continuum of an anesthetic if you are not a fan of deep extubations. Most people don't remember this phase but that is not to say all.... and these patients may perceive their experience as a case with “awareness” under anesthesia.

MAC awake is generally 1/3 of MAC, but for nitrous it’s about 2/3 of MAC. I’ve never had anybody have recall during any of my cases... and I'm one of those people who runs .5 MAC routinely, especially if I have a paralyzed patient with an ETT (balanced anesthetic technique with other meds on board). If they get light, I will pick it up with vitals not a patient moving. Excluding some valvular patients, a HR in the mid 40-60’s and nml B.P. + .5 MAC is all good in the hood IMO.

I know that Ireland anesthesiologists may be a bit different with their average MAC's for a case (at least at the hospital where I was at... and other RCSI med students rotated through). I remember hearing people say that “americans” using .5 MAC are looking for trouble and saw 1.4 MAC being utilized often. This was many years ago. It may be a culture thing that has changed or only present at the hospital I worked at.

Loved the scone and tea breaks...and the billion holidays... and the 9:00 theatre times... and the induction rooms....but what’s up with the milk in the tea and black/red pudding? 😉

As my Irish anesthesia mentor used to say....

Go raibh maith agatand and all the best,

Sevo

 

[hoyden]

How many of you routinely mention awareness during your consent talk? (I don't talk about it unless they ask.)

I talk about it with all MAC cases, since the media and entertainment world made the issue highly popular and therefore I feel there is a need to explain the difference between MAC and GA and what one should expect and when.