CNN article re: awareness under anesthesia

[Urzuz]

Thought you all may be interested:

http://www.cnn.com/2014/11/28/health/wake-up-during-surgery/index.html?hpt=hp_t3

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[caligas]

"Patients who were told about awareness before surgery were prepared and not distressed when they experienced it," he says.

That makes sense, not.

 

[jwk]

Good grief - Carol Weihrer is still spouting off about this 16 years after her incident, and for some unknown reason, the media keeps talking about it.

At least the idea that the incidence is 1:1000 cited by Levy the Clueless is no longer accepted.

 

[Planktonmd]

The never ending story of Carol Weihrer...
She had 14 surgeries on her eye and probably was on major opiates and sedatives before the enucleation surgery where she suffered the alleged awareness.
Could that have been a factor in her high tolerance or resistance to anesthesia???

 

[pgg]

Good grief - Carol Weihrer is still spouting off about this 16 years after her incident, and for some unknown reason, the media keeps talking about it.

Everyone needs a hobby ...

And it's a scary subject, so of course the media eats it up.


I don't think I've ever heard a credible first-hand awareness under GA story from a patient. Lots of friends/family who had it happen, lots of recall stories during colonoscopies. I sometimes wonder if most patients who think they "woke up" during surgery are simply confabulating a memory from an anesthesia dream. I mean, if the guy shooting heroin and ketamine in the 7/11 bathroom says he saw little green men, we don't go looking for them.

Or maybe I'm nuts and the CRNAs are on to something when they flush the midazolam "premed" in with 200 mg of propofol ...

 

[seinfeld]

Its all about communication

Spinals, MAC I always prep with you have a chance of in and out memories, I do not guarantee 100% amnesia, only 99%

Also i always talk about how they will wake up in the OR with a breathing tube in, most will be a sleep walking state but some do remember it coming out. THey will hear people talking around them as they wake up.

If a patient asks about being aware I go through the whole scenario with them. The true risks, the liklihood of when it occurs

 

[Promethean]

Oh, I've heard a legit story from a patient. A kid told us every word that was said in the room during his procedure. Complete accuracy. He had been intubated and relaxed for the procedure. Thanks to local anesthetic, fentanyl, and midazolam, he denied pain or anxiety about the event, but his awareness and recall were not affected.

Even people involved in the case argued that the midazolam should have made recall impossible. But some are quite resistant to its amnestic properties. I've received it for several "conscious sedation" procedures without impairing my memory of events. I don't have tolerance, don't drink very often or use any recreational drugs, and it does work on me as an anxiolytic, but I have been given fairly large doses IV without becoming unconscious or amnestic. I was relaxed enough to keep still and calm while the work was done, and I scared the heck out of the proceduralist when I opened my eyes and spoke to them clearly when they thought I was totally sedated. I had to reassure them that no, I wasn't in distress and didn't need more drugs, that they could do what they still needed to do and I would go back to listening quietly.

Just because someone isn't responsive, that is no guarantee that their sense of hearing or their memory will be impaired. Thus it is important to watch how one speaks and behaves in the presence of a patient, no matter their apparent level of consciousness.

 

[urge]

Oh, I've heard a legit story from a patient. A kid told us every word that was said in the room during his procedure. Complete accuracy. He had been intubated and relaxed for the procedure. Thanks to local anesthetic, fentanyl, and midazolam, he denied pain or anxiety about the event, but his awareness and recall were not affected.

Even people involved in the case argued that the midazolam should have made recall impossible. But some are quite resistant to its amnestic properties. I've received it for several "conscious sedation" procedures without impairing my memory of events. I don't have tolerance, don't drink very often or use any recreational drugs, and it does work on me as an anxiolytic, but I have been given fairly large doses IV without becoming unconscious or amnestic. I was relaxed enough to keep still and calm while the work was done, and I scared the heck out of the proceduralist when I opened my eyes and spoke to them clearly when they thought I was totally sedated. I had to reassure them that no, I wasn't in distress and didn't need more drugs, that they could do what they still needed to do and I would go back to listening quietly.

Just because someone isn't responsive, that is no guarantee that their sense of hearing or their memory will be impaired. Thus it is important to watch how one speaks and behaves in the presence of a patient, no matter their apparent level of consciousness.

I'm sure the parents were thrilled to hear their child wasn't properly anesthetized.

Any reason why they skimped on anesthetic?

 

[Promethean]

So, you know they skimped on anesthetic? I wasn't at the QA on the case, but from those who were, it sounded like he got reasonable doses of several agents.

Patient was still (relaxed, in fact!), intubated, vitals were steady... without a BIS monitor, which is not standard of care, how was anyone to know that he was aware? The kid himself wasn't freaked out about it, but I would say that the providers involved were far more upset than the family. This sort of thing is exceedingly rare and very disturbing to people who make a career out of making sure it never happens.

I think the parents were more upset at some of the swear words the kid learned from the surgeons than from the awareness.

 

[deleted59964]

so this thread gets legs - but NAP5 doesn't?

 

[urge]

So, you know they skimped on anesthetic?

Based on the end result, yes. I would say they are much better at predicting the dose/effect for muscle relaxants than they are for hypnotics.

I always find fascinating that when anesthesiologists talk about their patients having awareness, they always say that the patient was cool with it. It's like the patient goes to nirvana while they operate on them awake. Your story is just one example. I have heard this stuff many times since residency. Yet, the patients that write the nasty letters to the hospital don't seem to have the same experience. Who anesthetized these patients? Nobody ever takes ownership of those.

 

[deleted59964]

personally i find it interesting that patients consider residual neuromuscular blockade to be accidental awareness.
they also more frequently reported residual neuromuscular blockade to be distressing.

i must admit I've had a few patients in recovery that I've given further doses of reversal to... I am now very careful about nerve stimulation and timing of reversal with neostigmine.

 

[pgg]

so this thread gets legs - but NAP5 doesn't?

Well, this is a thread of stories and snark and idle amusement; your NAP5 thread was an attempt at a serious discussion about a topic I don't believe to be a significant risk in my practice.

I honestly, truly don't believe recall is a serious risk for my patients. I talk to them. I tell them exactly and SPECIFICALLY what my intent is with their anesthetic, I actually use that phrase ("my intent") and tell them what I expect. I emphasize the possibility that they might be aware something's going on or hear and remember voices if it's a sedation case. If my plan is an awake extubation I tell them ahead of time that when they wake up the tube will be coming out and they might remember it, but it won't be uncomfortable and there's nothing wrong if they remember that. The nature of my practice is that I rarely do TIVAs; for the ones I do I avoid relaxants if possible and use a Bis. If they're high risk and there's time (trauma/OB) I emphasize that my priority is to keep them safe first and asleep second. Beyond that, I pay attention and don't forget to turn the gas on. There, that's about 3/4 of the sixty-four recommendations that came out of NAP5.

 

[pgg]

personally i find it interesting that patients consider residual neuromuscular blockade to be accidental awareness.
they also more frequently reported residual neuromuscular blockade to be distressing.

i must admit I've had a few patients in recovery that I've given further doses of reversal to... I am now very careful about nerve stimulation and timing of reversal with neostigmine.

This was the topic of our residents' journal club last month.

I think the data is pretty clear that NMBDs are overused and overdosed; that almost everyone who got a dose of a nondepolarizer deserves at least some reversal, even if they have 4 strong twitches; that subjective evaluations of muscle strength like grip and head lift are very poor; that residual weakness in the PACU is very common and although probably not physiologically significant very often it's probably psychologically significant. I think twitch monitoring should be a standard of care (as in an ASA standard monitor in cases utilizing NMBDs), and maybe we ought to adopt the use of quantitative monitors.

 

[Ipassgas]

Based on the end result, yes. I would say they are much better at predicting the dose/effect for muscle relaxants than they are for hypnotics.

I always find fascinating that when anesthesiologists talk about their patients having awareness, they always say that the patient was cool with it. It's like the patient goes to nirvana while they operate on them awake. Your story is just one example. I have heard this stuff many times since residency. Yet, the patients that write the nasty letters to the hospital don't seem to have the same experience. Who anesthetized these patients? Nobody ever takes ownership of those.

I may or may not have had one of those upset people who stayed awake through intubation. It was possibly a rapid sequence in a robust individual who may have only been stunned by the possible full stick of propofol.

 

[McPoyle]

This was the topic of our residents' journal club last month.

I think the data is pretty clear that NMBDs are overused and overdosed; that almost everyone who got a dose of a nondepolarizer deserves at least some reversal, even if they have 4 strong twitches; that subjective evaluations of muscle strength like grip and head lift are very poor; that residual weakness in the PACU is very common and although probably not physiologically significant very often it's probably psychologically significant. I think twitch monitoring should be a standard of care (as in an ASA standard monitor in cases utilizing NMBDs), and maybe we ought to adopt the use of quantitative monitors.

So, what I can't understand and have a hard time getting any reasoning for from my attendings is "how do I dose reversal in cases where people 'only need a little'"?

It seems to often times be an arbitrary amount. Generally either 1, 2.5, or 5mg with little reasoning as to why that dose is asked for?

 

[urge]

I may or may not have had one of those upset people

lol

I'm sure you did not. You probably get thank you flowers on the anniversary of the intubation.

 

[Hoya11]

I think it happens VERRY rarely (less than 1 in a million anesthetics id estimate). I think it is more likely that these stories are fiction/confabulation/MAC cases in most cases.

 

[pgg]

So, what I can't understand and have a hard time getting any reasoning for from my attendings is "how do I dose reversal in cases where people 'only need a little'"?

It seems to often times be an arbitrary amount. Generally either 1, 2.5, or 5mg with little reasoning as to why that dose is asked for?

I use 20 mcg/kg because
1) there's data suggesting it's enough to eliminate residual blockade
2) because it's not enough to cause paradoxical effects
3) because below 2.5 mg total dose there doesn't appear to be a high risk of PONV
4) because there is lots of evidence that patients may have significant residual weakness in the PACU after even a single intubating dose of relaxant with 4 strong twitches

So I give everybody with 4 twitches and no discernible fade (itself an unreliable assessment) at least the 20 mcg/kg reduced dose (+ glyco of course) if they've had any nondepolarizer at all in the previous 2 hours. 2 hours is somewhat arbitrary but lots of things can prolong roc's 1/2 life; it's not just gone in a hour.


10-30 mcg/kg was found to reliably reverse shallow NM blockade in this article:
Antagonism of Low Degrees of Atracurium-induced Neuromuscular Blockade (Anes 2010 Vol 112:34 – 40)
They do add the caveat that their dose recommendations may not apply to other relaxants. Same article states that 40 mcg/kg but not 20 mcg/kg may have paradoxical effects. It also suggests that a full dose (50-70 mcg/kg) is probably unnecessary in patients with 4 equal twitches.

This one used 30 mcg/kg in fully recovered patients and got paradoxical weakness
Neostigmine/glycopyrrolate administered after recovery from neuromuscular block increases upper airway collapsibility by decreasing genioglossus muscle activity in response to negative pharyngeal pressure. (Anes 2010 Vol 113:1280-8)

This article states that 20-40 mcg/kg is "preferable to doing nothing, when four twitches appear equal." Ringing endorsement, sure.
Reversal of neuromuscular blockade: current practice and future directions (Donati, Anes Rounds 2009 Vol 8 Issue 3)

Ronald Miller checks the appeal-to-authority box need when he says everyone should be reversed in this editorial:
Monitoring and Pharmacologic Reversal of a Nondepolarizing Neuromuscular Blockade Should Be Routine (A&A 2010 Vol 111 No 1)
This issue of A&A is good reading on this topic, with a two part review article (Lessons Unlearned) and more.

 

[Promethean]

I always find fascinating that when anesthesiologists talk about their patients having awareness, they always say that the patient was cool with it. It's like the patient goes to nirvana while they operate on them awake.

To be clear, I am not an anesthesiologist. I am a particularly observant and collegial OR nurse who is bound for medical school. However, I was the circulating nurse involved with a follow up procedure on the kid with the intra-op awareness, and talked with him about his experience. He did seem really chill about it, which I attribute to appropriate dosing of midazolam and fentanyl despite inadequate inhalational agent. My sample size is small, though.
n of 1.

 

[Ipassgas]

lol

I'm sure you did not. You probably get thank you flowers on the anniversary of the intubation.

Let's just say I may be possibly counting those anniversaries, even if he or she is not.

The potential memories may have ended with possibly supplemental propofol given in response to tachycardia with laryngoscopy. Or not. Maybe.

Late edit: I may have asked the CRNA a whatthehell! sort of question. It may be that I found out versed was omitted because "s/he seemed chill." Despite it being part of the plan. CRNAs, gooder, fasterer, cheaper-ishier, coming to an OR near you!

 

[BuzzPhreed]

I think it happens VERRY rarely (less than 1 in a million anesthetics id estimate). I think it is more likely that these stories are fiction/confabulation/MAC cases in most cases.

Agreed.

At this point in my career I've personally been involved in (either directing or actually providing myself) over 10,000 anesthetics. I've yet to have any patient complain of true "awareness" under anesthesia after the fact. I've occasionally had patients in the pre-op interview tell me they were "awake" during part their operation, but invariably it was a recollection of emergence at the end of the case, being in the PACU, briefly hearing a saw or something under spinal/MAC during a TKA, or some other part of the peri-operative course where they were still under the effects of medication but were not, like the move "Awake", actually fully aware of being operated on, in pain, freaked-out, etc.

A big part of this ongoing discussion is what actually constitutes "awareness" under anesthesia. Point is, if you have a super nervous Nelly in the holding area, step hard on the midazolam pedal.

 

[jwk]

So, you know they skimped on anesthetic? I wasn't at the QA on the case, but from those who were, it sounded like he got reasonable doses of several agents.

Patient was still (relaxed, in fact!), intubated, vitals were steady... without a BIS monitor, which is not standard of care, how was anyone to know that he was aware? The kid himself wasn't freaked out about it, but I would say that the providers involved were far more upset than the family. This sort of thing is exceedingly rare and very disturbing to people who make a career out of making sure it never happens.

I think the parents were more upset at some of the swear words the kid learned from the surgeons than from the awareness.

Sorry - honestly, I don't think you have the total story or understanding of this. Random thoughts...

"Reasonable doses of several agents" - I don't know about your place, but when we're talking about "agents", we're talking about inhalation agents, and we don't use several of them. We might switch from one to another after induction, or use an inhalation agent plus N2O, but that's it. Midazolam, fentanyl, etc. are not typically referred to as agents. And I agree with Urge - they skimped on agent - or maybe forgot to turn it on, or the vaporizer ran dry. Absent something else going on (deliberately going light on various drugs because of trauma, OB, or in open heart cases) awareness shouldn't happen in any case, even a TIVA. If your patient can recite back to you what was said throughout the case, that's pretty much a screwup.

BIS is not standard of care - but I use it quite frequently. It's surprising how little, or how much, "agent" is required on different patients. I think there are many who go light on agent when they're going more multi-modal with their technique, or of course no agent when using a TIVA technique. Those patients need special attention to make sure the risk of awareness is minuscule.

Not sure what you consider "reasonable" doses, or what you received in your personal experience as a "fairly large dose". If anesthesia personnel are involved, there is almost no reason to give a large dose of midazolam. There are better ways to sedate someone - propofol for example. Now, if your sedation was nurse-administered as directed by a non-anesthesiologist physician, then all bets are off since many are remarkably clueless about adequate and safe procedural sedation.

 

[urge]

Sorry - honestly, I don't think you have the total story or understanding of this. Random thoughts...

"Reasonable doses of several agents" - I don't know about your place, but when we're talking about "agents", we're talking about inhalation agents, and we don't use several of them. We might switch from one to another after induction, or use an inhalation agent plus N2O, but that's it. Midazolam, fentanyl, etc. are not typically referred to as agents. And I agree with Urge - they skimped on agent - or maybe forgot to turn it on, or the vaporizer ran dry. Absent something else going on (deliberately going light on various drugs because of trauma, OB, or in open heart cases) awareness shouldn't happen in any case, even a TIVA. If your patient can recite back to you what was said throughout the case, that's pretty much a screwup.

BIS is not standard of care - but I use it quite frequently. It's surprising how little, or how much, "agent" is required on different patients. I think there are many who go light on agent when they're going more multi-modal with their technique, or of course no agent when using a TIVA technique. Those patients need special attention to make sure the risk of awareness is minuscule.

Not sure what you consider "reasonable" doses, or what you received in your personal experience as a "fairly large dose". If anesthesia personnel are involved, there is almost no reason to give a large dose of midazolam. There are better ways to sedate someone - propofol for example. Now, if your sedation was nurse-administered as directed by a non-anesthesiologist physician, then all bets are off since many are remarkably clueless about adequate and safe procedural sedation.

Can you imagine if the media starts riding the 'Awareness on children' train?

 

[urge]

Let's just say I may be possibly counting those anniversaries, even if he or she is not.

The potential memories may have ended with possibly supplemental propofol given in response to tachycardia with laryngoscopy. Or not. Maybe.

Tic Toc, Tic Toc.....

You should be fine by the 5th anniversary.

Tic Toc...

 

[Promethean]

Sorry - honestly, I don't think you have the total story or understanding of this. Random thoughts...

I was not using the term agent in the anesthesia specific sense, but rather in a wider sense of "medication being employed toward a particular goal." I will use the term "medication" going forward, for your comfort.

All of our surgical anesthetics are directed by anesthesiologists, though closely supervised CRNAs and residents are involved in most cases as well. Almost all use midazolam as a pre-med, while some layer in an additional dose once an IV has been established. They discuss its amnestic potential as if it were universal and utterly reliable, which has not been my personal experience of that drug.

I'm not debating that the patient didn't get enough medications to do the job, just that he was given doses that are routinely effective for others and there was no reason to think that they would be ineffective for him. I have questioned whether the vapor was allowed to run dry, but that explanation doesn't make sense given the staff involved in the case. Even if they had failed to check the machine, they surely would have noticed the inspired/exhaled sevo levels were off, and they certainly wouldn't have charted otherwise. Rather, my assertion is that if an entire anesthesia department was left scratching their heads about how he could have remembered so much despite the doses and range of medications provided to him, then it isn't unreasonable to at least question whether there might be some patient specific factor involved.

He did not experience recall after the subsequent procedure in which I was involved, as that anesthesiologist thoroughly snowed him and did use BIS monitoring despite the brevity of the case.

As for midazolam: "A fairly large dose" that I have been given personally is 15 mg of midazolam IV up front, followed by 1-2 mg boluses later in the procedure. That is significantly larger than the doses I usually see given IV to our peds patients, even those who outweigh me. That dose was profoundly anxiolytic, but it did not produce unconsciousness nor impair my recall of events. Thus, I don't place blind faith in the notion that 1-2 mg IV pre-op will ensure that patients won't hear and remember conversations leading up to induction. So, I manage the conversations that are permitted in my room when patients are being induced. If it isn't quiet, calm, and relevant to the patient on the table, it can wait.

 

[jwk]

I was not using the term agent in the anesthesia specific sense, but rather in a wider sense of "medication being employed toward a particular goal." I will use the term "medication" going forward, for your comfort.

All of our surgical anesthetics are directed by anesthesiologists, though closely supervised CRNAs and residents are involved in most cases as well. Almost all use midazolam as a pre-med, while some layer in an additional dose once an IV has been established. They discuss its amnestic potential as if it were universal and utterly reliable, which has not been my personal experience of that drug.

I'm not debating that the patient didn't get enough medications to do the job, just that he was given doses that are routinely effective for others and there was no reason to think that they would be ineffective for him. I have questioned whether the vapor was allowed to run dry, but that explanation doesn't make sense given the staff involved in the case. Even if they had failed to check the machine, they surely would have noticed the inspired/exhaled sevo levels were off, and they certainly wouldn't have charted otherwise. Rather, my assertion is that if an entire anesthesia department was left scratching their heads about how he could have remembered so much despite the doses and range of medications provided to him, then it isn't unreasonable to at least question whether there might be some patient specific factor involved.

He did not experience recall after the subsequent procedure in which I was involved, as that anesthesiologist thoroughly snowed him and did use BIS monitoring despite the brevity of the case.

As for midazolam: "A fairly large dose" that I have been given personally is 15 mg of midazolam IV up front, followed by 1-2 mg boluses later in the procedure. That is significantly larger than the doses I usually see given IV to our peds patients, even those who outweigh me. That dose was profoundly anxiolytic, but it did not produce unconsciousness nor impair my recall of events. Thus, I don't place blind faith in the notion that 1-2 mg IV pre-op will ensure that patients won't hear and remember conversations leading up to induction. So, I manage the conversations that are permitted in my room when patients are being induced. If it isn't quiet, calm, and relevant to the patient on the table, it can wait.

Sounds like a scary place to me - seriously.

 

[epidural man]

I wonder if a lot of awareness cases happen to be before the tube is pulled at the end of the case - perhaps just as the last suture is going in, or the dressing applied.

I would prefer all my patients be quit aware at this point. My favorite part of doing anesthesia is when I tell the patient -
"your surgery is over - move over to that bed right there" - and they are able to do it.

I couldn't do that if they were still "unaware" as the dressing was being applied.

 

[Arch Guillotti]

I don't think I've ever heard a credible first-hand awareness under GA story from a patient. Lots of friends/family who had it happen, lots of recall stories during colonoscopies. I sometimes wonder if most patients who think they "woke up" during surgery are simply confabulating a memory from an anesthesia dream. I mean, if the guy shooting heroin and ketamine in the 7/11 bathroom says he saw little green men, we don't go looking for them.

Or maybe I'm nuts and the CRNAs are on to something when they flush the midazolam "premed" in with 200 mg of propofol ...

I know of 3 cases of awareness. All CRNA's. None were my cases thankfully but I heard enough details from people directly involved that I know they were the real thing.

Giving the midazolam with the propofol makes no sense to me either and I see it done not infrequently unfortunately.

 

[nap$ter]

I was not using the term agent in the anesthesia specific sense, but rather in a wider sense of "medication being employed toward a particular goal." I will use the term "medication" going forward, for your comfort.

All of our surgical anesthetics are directed by anesthesiologists, though closely supervised CRNAs and residents are involved in most cases as well. Almost all use midazolam as a pre-med, while some layer in an additional dose once an IV has been established. They discuss its amnestic potential as if it were universal and utterly reliable, which has not been my personal experience of that drug.

I'm not debating that the patient didn't get enough medications to do the job, just that he was given doses that are routinely effective for others and there was no reason to think that they would be ineffective for him. I have questioned whether the vapor was allowed to run dry, but that explanation doesn't make sense given the staff involved in the case. Even if they had failed to check the machine, they surely would have noticed the inspired/exhaled sevo levels were off, and they certainly wouldn't have charted otherwise. Rather, my assertion is that if an entire anesthesia department was left scratching their heads about how he could have remembered so much despite the doses and range of medications provided to him, then it isn't unreasonable to at least question whether there might be some patient specific factor involved.

He did not experience recall after the subsequent procedure in which I was involved, as that anesthesiologist thoroughly snowed him and did use BIS monitoring despite the brevity of the case.

As for midazolam: "A fairly large dose" that I have been given personally is 15 mg of midazolam IV up front, followed by 1-2 mg boluses later in the procedure. That is significantly larger than the doses I usually see given IV to our peds patients, even those who outweigh me. That dose was profoundly anxiolytic, but it did not produce unconsciousness nor impair my recall of events. Thus, I don't place blind faith in the notion that 1-2 mg IV pre-op will ensure that patients won't hear and remember conversations leading up to induction. So, I manage the conversations that are permitted in my room when patients are being induced. If it isn't quiet, calm, and relevant to the patient on the table, it can wait.

you make a lot of assumptions.

it amazes me how many people still use the BIS.

you are not normal in some way if you got 15mg of IV midazolam and had perfect recall.

 

[dpmd]

I have had one patient aware during anesthesia and he was definitely not cool with it. He could recall stuff i said during (thankfully i didn't say anything bad) as well the fact i was moving the table and getting a step at certain points. Was unquestionably legitimate. He was paralyzed and could feel everything i did so it was understandably traumatized. I know the anesthesiologist wasn't able to give him much during the case because he was so unstable (bad bleeding ulcer in a patient with multiple prior operations so it took a while before i could actually stop the bleeding, plus his pressure to start with was 50 systolic) plus the guy had some serious medication tolerance. Made for a very interesting post op course.

 

[epidural man]

you make a lot of assumptions.

it amazes me how many people still use the BIS.

you are not normal in some way if you got 15mg of IV midazolam and had perfect recall.

I love the BIS - very useful monitor.

 

[deleted171991]

I love the BIS - very useful monitor.

There is a useless I in the middle.

 

[Arch Guillotti]

I love the BIS - very useful monitor.

I hate it.

 

[epidural man]

I hate it.

Why?

 

[risnwb]

Why?

I'm guessing because it's worthless

 

[jwk]

Ya gotta use BIS enough to get used to it and understand what it is and isn't, what it does and doesn't do. It's not necessary for every case, but for some it's great.

 

[nap$ter]

Ya gotta use BIS enough to get used to it and understand what it is and isn't, what it does and doesn't do. It's not necessary for every case, but for some it's great.

it's a random number generator that has been debunked.

i haven't used it since residency (when i was forced to by the weaker attendings).

 

[urge]

Ya gotta use BIS enough to get used to it and understand what it is and isn't, what it does and doesn't do. It's not necessary for every case, but for some it's great.

I agree. I think it is good for TIVA and for CPB. I don't see much benefit in regular cases.

 

[BuzzPhreed]

Ya gotta use BIS enough to get used to it and understand what it is and isn't, what it does and doesn't do. It's not necessary for every case, but for some it's great.

No you don't. And no it isn't.

 

[epidural man]

it's a random number generator that has been debunked.

i haven't used it since residency (when i was forced to by the weaker attendings).

This is an absolute ******ed statement. It is not a random number generator. It absolutely montiors anesthetic depth. I will bet you 1 million dollars that if you have 10 awake patients with a baseline BIS, then you give an induction dose of propofol, all of them will have a decrease in BIS numbers.

To say that it is a random number generator shows you have a complete lack of understanding of what the BIS represents, how it is calculated, and the basic science behind anesthetic depth. In addition, I personally feel it shows that you have personal bias that clouds judgement as well as some pride issues not allowing you to see clearly.

It has not been debunked. Show me an article that shows that BIS doesn't generally measure anesthetic depth. And don't show me crap about it not preventing awareness...I haven't said a thing about awareness or prevention of awareness. BIS has no utility in preventing awareness - everyone agrees with that. But to say the technology of bispectral index and EEG processing to measure anesthetic depth is crap is - once again - very naive.

 

[nap$ter]

This is an absolute ******ed statement. , I personally feel it shows that you have personal bias very naive.

let's not make this personal, slim.

you owe me one million dollars (said like dr. evil wit jeweled pinky to corner of mouth). I select the last ten patients I had a BIS on - all but the last one had a decrease in number with propofol. (BTW, "random number generator" is a joking exaggeration of fact, not a statement of data).

the last patient i had a BIS on was in residency. 30something IVDA'er for I and D, concern for nec fasc. Fluids going in, BP 100/60, HR 120. Came to preop 2 days into a crash from crack withdrawal (also enjoyed heroin in her spare time), vacillating between barely arousable and jitteryjumpinanxious100outof10paindoc....

(weak) attending puts the BIS on before induction. 42. her awake BIS number was 42. Induction with 100 of propofol, 100 of ketamine, 120 of sux, laryngoscopy. BIS goes to 60's and stays there throughout the case (pt spont ventilating, no response to surgical stimulus). attending spent the case freaking out giving propofol, midazolam, ketamine, volatile, and scopolamine bolusses (and increasing doses of phenylephrine) - no change in BIS. He was worried she was going to move, have postop pain, awareness, etc...Emergence was... delayed.... to the tune of 8 hours on a vent in the ICU (granted this was multifactorial).. the BIS gave misleading information regarding the depth of anesthetic.

you admit that the BIS has been debunked regarding awareness prevention. there may be hope for you. you likely vaccinated your kids.

it does yield information regarding some combination of emg and eeg. what combination? i dunno - cuz the algorithm is a SECRET. i refuse to use monitors unless the logistics are TRANSPARENT. does the number correlate with anesthetic depth? SOMETIMES, MAYBE. Is the number useful ie does it add to the quality of our patient care? NO. can adjustment of anesthetic regimen based on a BIS number be harmful? YES (cost aside) - i have personally seen this happen on a number of occasions as a resident when done by (weak) attendings who were self proclaimed experts on the subject of the BIS.

you ask for an example that "BIS doesn't generally measure anesthetic depth" (aside from the anecdotes above) - here ya go:

Anesth Analg. 2003 Aug;97(2):488-91, table of contents.
The bispectral index declines during neuromuscular block in fully awake persons.
Messner M1, Beese U, Romstöck J, Dinkel M, Tschaikowsky K.

this is just one example of many. paralysis does not equal anesthetic depth. different drugs (and combinations of drugs) achieving similar anesthetic depths by traditional monitoring yield very very different BIS numbers. the stupid thing uses emg and eeg to give you a number. the device is useless, expensive, and potentially (mildly) harmful.

i know from experience in debating this issue with multiple folks over the years that you will very likely paste some studies in here showing that you are right - the issue for some reason remains controversial.

i'm not gonna argue with you (this debate could go on forever). go right ahead and use the bis all you want - but if i take over your patient/room sometime i will politely remove the BIS (after you leave the room), throw it in the trash, and do the next right thing.

merry christmas

 

[fakin' the funk]

I use 20 mcg/kg because
1) there's data suggesting it's enough to eliminate residual blockade
2) because it's not enough to cause paradoxical effects
3) because below 2.5 mg total dose there doesn't appear to be a high risk of PONV
4) because there is lots of evidence that patients may have significant residual weakness in the PACU after even a single intubating dose of relaxant with 4 strong twitches

PGG, thanks for this awesome post.

Proper dosing and monitoring of NDNMB, dosing and timing of reversal, effects of NDNMB and its reversal, are poorly understood and poorly taught (in my experience). It's an area where what I believe is or should be the standard of care is far from "standard" either in academics or in the real world. If you look at those surveys, I think it's something like half of anesthesia practitioners do ANY monitoring during nondepolarizing blockade. That's scary.

Certainly in training, residents use WAYYY too much NDNMB both at the time of induction and for maintenance, and for a lot of reasons.

Where I did residency, we had just got premade 100mg rocuronium syringes available in our carts. Perhaps not surprisingly, there were a lot of weak patients in our PACU getting re-intubated for a while.

I prefer to look a NDNMBs as a drug class to avoid if possible and fear (i.e. treat with respect), rather than a "routine" drug class.

 

[urge]

the last patient i had a BIS on was in residency. 30something IVDA'er for I and D, concern for nec fasc. Fluids going in, BP 100/60, HR 120. Came to preop 2 days into a crash from crack withdrawal (also enjoyed heroin in her spare time), vacillating between barely arousable and jitteryjumpinanxious100outof10paindoc....

(weak) attending puts the BIS on before induction. 42. her awake BIS number was 42. Induction with 100 of propofol, 100 of ketamine, 120 of sux, laryngoscopy. BIS goes to 60's and stays there throughout the case (pt spont ventilating, no response to surgical stimulus). attending spent the case freaking out giving propofol, midazolam, ketamine, volatile, and scopolamine bolusses (and increasing doses of phenylephrine) - no change in BIS. He was worried she was going to move, have postop pain, awareness, etc...Emergence was... delayed.... to the tune of 8 hours on a vent in the ICU (granted this was multifactorial).. the BIS gave misleading information regarding the depth of anesthetic.

That's not a good example. Ketamine is known to raise the BIS.

The BIS can be dangerous in certain hands. That's not a good statement either. Let me fix it:

Some hands are just dangerous.

Muscle relaxants do decrease the BIS, but the machine tells you how much the emg is playing a role in the calculation. It's not like you are rendered oblivious to it. You cannot just treat a number. I think that's why people who don't get it trash it so much.

 

[nap$ter]

That's not a good example. Ketamine is known to raise the BIS.

The BIS can be dangerous in certain hands. That's not a good statement either. Let me fix it:

Some hands are just dangerous.

Muscle relaxants do decrease the BIS, but the machine tells you how much the emg is playing a role in the calculation. It's not like you are rendered oblivious to it. You cannot just treat a number. I think that's why people who don't get it trash it so much.

my point with the ketamine example is that different drugs and different combinations of drugs yield different BIS numbers. the BIS does not measure depth of anesthesia - it measures the the effect of different drugs. the infinite number of possible drug/dose combinations and patient/surgical factors render the number relatively useless - it does not add to quality of care and may mislead (usuallly leading to false reasssurance or overdosing of anesthesia). epidural man still owes me one million dollars - his bet did not disqualify other drugs given with induction (propofol is almost never the only drug given with induction).

BIS number does not predict movement or hemodynamic response to surgical stimulation, so how is it valuable?

the original statement and your statement are true:

hands that rely on the BIS can be dangerous, AND some hands are just dangerous.

it's like arguing with my ex-wife - if i didn't agree with her she would accuse me of ignorance

BIS naysayers "get it" just fine - we just disagree with you based on the facts.

so the machine tells you how much the emg is factored into the number output? tell me how that works, urge, because last time i checked the algorithm remains UNPUBLISHED ie SECRET. just because the machine gives you some info about emg activity and signal quality index doesn't mean that information is useful. it's just NOISE.

 

[urge]

so the machine tells you how much the emg is factored into the number output? tell me how that works, urge, because last time i checked the algorithm remains UNPUBLISHED ie SECRET. just because the machine gives you some info about emg activity and signal quality index doesn't mean that information is useful. it's just NOISE.

I think you are splitting hairs. The emg scale is on the monitor. It's your job to interpret that too.

 

[Arch Guillotti]

I'm guessing because it's worthless

What he said. The nurses love it though.

I think it is great for MAC cases and kids especially

 

[BuzzPhreed]

Did literally everyone miss this paper?

"We did not reproduce the results of previous studies that reported a lower incidence of anesthesia awareness with BIS monitoring, and the use of the BIS protocol was not associated with reduced administration of volatile anesthetic gases. Anesthesia awareness occurred even when BIS values and ETAG concentrations were within the target ranges. Our findings do not support routine BIS monitoring as part of standard practice."

http://www.nejm.org/doi/full/10.1056/NEJMoa0707361

I have an anecdote equal to or maybe even better than nap$ster's.

We got a bunch of BIS monitors towards the end of my residency. Mine outside the box case was on a GA for (IDK excatly now it was 7-8 years ago at this point) a big ventral hernia repair or something. The guy's BIS was 80+ after induction and even after cranking the sevo up to 1.5 MAC and pushing propofol which only made his pressure plunge. My attending was freaking out. The guy got almost 30mg of midazolam for a slightly longer than two-hour procedure, because every time you'd give 2-3 mg, the BIS would dump down into the low 70's or upper 60's. We changed the strip, repositioned him, did just about everything. 2-3 mg of midaz and 5-10 minutes after dipping it would start to creep back up into the 80's.

That patient was supposed to go home. Spent two days in the hospital. I don't think he remembered anything for the first 24 hours.

 

[epidural man]

let's not make this personal, slim. How do you know I am skinny?

you owe me one million dollars (said like dr. evil wit jeweled pinky to corner of mouth). I select the last ten patients I had a BIS on - all but the last one had a decrease in number with propofol. (BTW, "random number generator" is a joking exaggeration of fact, not a statement of data).

the last patient i had a BIS on was in residency. 30something IVDA'er for I and D, concern for nec fasc. Fluids going in, BP 100/60, HR 120. Came to preop 2 days into a crash from crack withdrawal (also enjoyed heroin in her spare time), vacillating between barely arousable and jitteryjumpinanxious100outof10paindoc....

(weak) attending puts the BIS on before induction. 42. her awake BIS number was 42. Induction with 100 of propofol, 100 of ketamine, 120 of sux, laryngoscopy. BIS goes to 60's and stays there throughout the case (pt spont ventilating, no response to surgical stimulus). attending spent the case freaking out giving propofol, midazolam, ketamine, volatile, and scopolamine bolusses (and increasing doses of phenylephrine) - no change in BIS. He was worried she was going to move, have postop pain, awareness, etc...Emergence was... delayed.... to the tune of 8 hours on a vent in the ICU (granted this was multifactorial).. the BIS gave misleading information regarding the depth of anesthetic.

you admit that the BIS has been debunked regarding awareness prevention. there may be hope for you. you likely vaccinated your kids.

it does yield information regarding some combination of emg and eeg. what combination? i dunno - cuz the algorithm is a SECRET. i refuse to use monitors unless the logistics are TRANSPARENT. does the number correlate with anesthetic depth? SOMETIMES, MAYBE. Is the number useful ie does it add to the quality of our patient care? NO. can adjustment of anesthetic regimen based on a BIS number be harmful? YES (cost aside) - i have personally seen this happen on a number of occasions as a resident when done by (weak) attendings who were self proclaimed experts on the subject of the BIS.

you ask for an example that "BIS doesn't generally measure anesthetic depth" (aside from the anecdotes above) - here ya go:

Anesth Analg. 2003 Aug;97(2):488-91, table of contents.
The bispectral index declines during neuromuscular block in fully awake persons.
Messner M1, Beese U, Romstöck J, Dinkel M, Tschaikowsky K.

this is just one example of many. paralysis does not equal anesthetic depth. different drugs (and combinations of drugs) achieving similar anesthetic depths by traditional monitoring yield very very different BIS numbers. the stupid thing uses emg and eeg to give you a number. the device is useless, expensive, and potentially (mildly) harmful.

i know from experience in debating this issue with multiple folks over the years that you will very likely paste some studies in here showing that you are right - the issue for some reason remains controversial.

i'm not gonna argue with you (this debate could go on forever). go right ahead and use the bis all you want - but if i take over your patient/room sometime i will politely remove the BIS (after you leave the room), throw it in the trash, and do the next right thing.

merry christmas

I need to address you points.

First - the article. This is a very interesting article that has been fun to discuss for years. I remember when it first came out. However, the BIS folks went back to the drawing board and improved the software to better filter EMG data. It still messes it up but it is much better. IN fact, I was doing a case as a resident - with the newest software on a BIS - had an LMA in, but the case needed apnea 3 times during the case - so I gave Sux. Each time I did, the BIS dropped significantly (even down to 19) and then returned. I suspect spontaneous breathing and return to breathing had something to do with it. I wrote the case up, and the journal wanted to not publish as a case report but as a letter to the editor so the company could respond. I got lazy and never resubmitted. But, you are right EMG does mess with the data so one has to take that into account. As Urge says, you have to notice the EMG line on the monitor and use that information.

Next - lets address this point about it improving outcomes. I think if you are going to hold BIS to this standard, you need to hold the SAME standard to every monitor you use, and if it hasn't been shown to improve outcomes, then to prevent yourself from being a miserable hypocrite, you need to disregard and stop using ALL monitors that don't show improved outcomes with its use. Think about the shape of the ETCO2 waveform. That waveform often contains such subtle but VERY useful information. I doubt the waveform shape has ever been documented to change outcomes - yet we rely on that rather heavily for many things. However, sometimes, the waveform is ridiculous and doesn't make any sense based on all our other inputed data. In this case, we don't rely on the information it is telling us. The same is true for all monitors. Have you ever been in a case where the a-line stopped being useful to you? I have many many times. Do I stop using A-lines because of it? How about the pulse-ox? Do I stop using it in all my cases because the last case I did gave me useless information? Once again, if your standard of BIS is that it needs to provide reliable and STAND ALONE information EVERY TIME, or it is a useless monitor, then you need to have this same standard for EVERY monitor you use.

Next, let's talk about propriatary engineering. I have heard anesthesiologists use this argument against BIS from the very beginning. It is very strange if you ask me. But again, we have to do our best not to be hypocrites. Is there anything else worse in this world than a hypocrite? I think we can all agree - no, there isn't. So, if you won't use BIS because they have a "secret" algorithm that they won't share, then you need to apply that SAME logic and standard to EVERYTHING you use. That means you will unlikely be able to use anything electronic at your work or in your home. Your ultrasound machine likely has secret software so the compound imaging makes things look beautiful. If you use spotify or something like it, it uses secret encryption software. You will need to throw your phone away today. It is LOADED with secret software. None of these companies say anything about the secrets they have created, nor apologize that you don't know what it is, or how it is done. Please apply the same standard you have for BIS to all technology around you.

I do not owe you 1 million dollars. You have to prove that BIS does not measure anesthetic depth. That is the bet. I never said it has to be reliable EVERY CASE in EVERY scenario. Actually, the bet is - that if you give proposal to 10 people from baseline, that in those 10 people, the BIS will drop.

By the way, I wouldn't not care one bit that if you took over a case for me and you took away the BIS because you don't like the information. I wouldn't care if you took out my a-line because you don't like that information either. Turn off the monitors and use an esophageal stethoscope and a manual blood pressure and your fingers - I don't care. Personally, I like having lots of different data points and then I get to use everything I know about limitations of those things providing data to see if it is useful and how I am going to interpret those points.

Every monitor can harm a patient if it is misinterpreted when it is not providing useful information. It is up to the physician to determine when it is useful information, and when it is not. I get it that you struggle to understand when a BIS is giving you useful information. I would disregard a monitor like that as well.

 

[nap$ter]

I think you are splitting hairs. The emg scale is on the monitor. It's your job to interpret that too.

no it is not my job to interpret emg on a BIS monitor...

i don't need to respond to epidural man's points. this debate isn't going to be productive.