Awareness Case

[cubs3canes]

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Hey all--interesting CA-1 case the other day

Day before..pt. in pre-op center. i get a page from my collegue. you have a patient tomorrow with a history of awareness at another facility (in which she is a SICu nurse at) for her lap chole. She remembered everything. She told the surgeons after the procedure the entire conversation. She was paralyzed. She did not sue. She had no bad motives. She just did not want to have awareness.

That Morning. She is a 48 year for bilateral submand. resection for saliolithiasis (sp and is that correct?). Midaz x 3mg in preop...back to OR.

Awake BIS monitor applied (88). Fentanyl 100mcg, propfol, sux (facial nerve exploration) easy mask, intubation..then des all the way up (BIS is 50). Started a propofol drip and titrated to BIS <30 for entire case. Gave 2 of mid every 30 min for first 1.5 hours then 2 more through out the case for a total of 11. (needed neo x 200mcg ...not much). Turn prop off and BIS to 50 in two minutes with etDES of 10.

Brought her back to the PACU intubated (on purpose). let the benzos and propfol wear off. ten minutes later she was awake and comfortable..nurse pulled the tube.

My attending then asked her after she was extubated how we did. She put both of her thumbs up and said thank you. I went and visited her after my next case and she was extactic. I was so proud that I could help her.

Crazy.

Cubs

 

[Planktonmd]

Hey all--interesting CA-1 case the other day

Day before..pt. in pre-op center. i get a page from my collegue. you have a patient tomorrow with a history of awareness at another facility (in which she is a SICu nurse at) for her lap chole. She remembered everything. She told the surgeons after the procedure the entire conversation. She was paralyzed. She did not sue. She had no bad motives. She just did not want to have awareness.

That Morning. She is a 48 year for bilateral submand. resection for saliolithiasis (sp and is that correct?). Midaz x 3mg in preop...back to OR.

Awake BIS monitor applied (88). Fentanyl 100mcg, propfol, sux (facial nerve exploration) easy mask, intubation..then des all the way up (BIS is 50). Started a propofol drip and titrated to BIS <30 for entire case. Gave 2 of mid every 30 min for first 1.5 hours then 2 more through out the case for a total of 11. (needed neo x 200mcg ...not much). Turn prop off and BIS to 50 in two minutes with etDES of 10.

Brought her back to the PACU intubated (on purpose). let the benzos and propfol wear off. ten minutes later she was awake and comfortable..nurse pulled the tube.

My attending then asked her after she was extubated how we did. She put both of her thumbs up and said thank you. I went and visited her after my next case and she was extactic. I was so proud that I could help her.

Crazy.

Cubs

Was she a read head by any chance?

 

[Noyac]

Was she a read head by any chance?

Good question.

Higher pain threshold, bleed easier, and awareness.

 

[milrisome]

She remembered EVERYTHING?!! Sounds like somebody forgot to turn on the vaporizer!

 

[BLADEMDA]

Agree with the preop Midazolam. With the BIS on her forehead and at least ONE MAC VAPOR plus propofol infusion why all the extra midazolam? The logic of MACHINE GUN anesthesia seems a bit over-kill.

Never heard or seen a case of ONE MAC VAPOR (exhaled gases) having recall.
Please provide just ONE EXAMPLE of a patient with intraoperative awareness with ONE MAC VAPOR. Then, you add the BIS (in her case I would want 40 or less) combined with propofol and even an elephant👍 wouldn't remember a thing.

Blade

 

[Idiopathic]

So, with awareness, almost all cases (that arent hypotensive traumas or cardiac surgery) have to do with incorrectly calibrated vaporizer, failure to deliver agent (empty or malfunction) or accidental syringe switching (i.e. succ before etomidate). i.e. operator error. Vigilance is your friend in these cases.

I agree with the above assessment. If you are confident that you are delivering a full MAC of agent, and your BIS is less than 50 (my target), then the rest of the stuff is probably not necessary.

BTW, cubs, did you really have the des up 'all the way'? It looks like when you turned the propofol off, you had a BIS of 50 with etdes of 10? Jesus, if I was running des at 1.5 MAC for a whole case AND giving midazolam q30 AND propofol drip, id pretty much throw away the BIS. What are you going to do if it read 65? You have no more anesthetic to give.

So, I would get the BIS, titrate to ~40, maybe 0.8 MAC and propofol drip at howevermany mcg/kg/min and only use midaz if the BIS creeps up above 60 or if they move.

 

[BLADEMDA]

So, with awareness, almost all cases (that arent hypotensive traumas or cardiac surgery) have to do with incorrectly calibrated vaporizer, failure to deliver agent (empty or malfunction) or accidental syringe switching (i.e. succ before etomidate). i.e. operator error. Vigilance is your friend in these cases.

I agree with the above assessment. If you are confident that you are delivering a full MAC of agent, and your BIS is less than 50 (my target), then the rest of the stuff is probably not necessary.

BTW, cubs, did you really have the des up 'all the way'? It looks like when you turned the propofol off, you had a BIS of 50 with etdes of 10? Jesus, if I was running des at 1.5 MAC for a whole case AND giving midazolam q30 AND propofol drip, id pretty much throw away the BIS. What are you going to do if it read 65? You have no more anesthetic to give.

So, I would get the BIS, titrate to ~40, maybe 0.8 MAC and propofol drip at howevermany mcg/kg/min and only use midaz if the BIS creeps up above 60 or if they move.

Your opinion is read and understood. But, for qualification purposes how many general anesthetics have you delivered? Are you basing your statements on vast clinical experience or published data? I am not trying to be rude but understand your clinical experience level. Awareness is a difficult issue but one that is vastly over-hyped by the media.

Blade

 

[Idiopathic]

It doesnt really matter, my points are valid.

You yourself said "Never heard or seen a case of ONE MAC VAPOR (exhaled gases) having recall.Please provide just ONE EXAMPLE of a patient with intraoperative awareness with ONE MAC VAPOR", and Im essentially agreeing with this.

Do you disagree with my assessment or just challenge my experience? Which part specifically would you attribute to lack of n=10,000 anesthetics? Cubs is new, and took a case in one direction, I also am new and would have taken it in a slightly different direction

 

[BLADEMDA]

It doesnt really matter, my points are valid.

You yourself said "Never heard or seen a case of ONE MAC VAPOR (exhaled gases) having recall.Please provide just ONE EXAMPLE of a patient with intraoperative awareness with ONE MAC VAPOR", and Im essentially agreeing with this.

Do you disagree with my assessment or just challenge my experience? Which part specifically would you attribute to lack of n=10,000 anesthetics? Cubs is new, and took a case in one direction, I also am new and would have taken it in a slightly different direction

Experience matters in the "grey areas" like recall. I wouldn't throw away the BIS on this patient. I would use it like TEE, A-line, etc. as a tool for additional information. Yes, ONE MAC exhaled vapor would make me confident of NO RECALL. But, due to this patient's history if the BIS was greater than 60 for anything more than a few seconds I would titrate the Propofol drip to decrease it. One MAC vapor plus 50-75 ug/kg/min should make this woman's BIS read below 50. If it didn't I would be concerned because we understand so little about true intra-op awareness.

As I have pointed out the incidence of awareness is about 1 in 14,500. I suspect with the use of exhaled gases and/or BIS it would be even lower.

Blade

 

[Idiopathic]

My point was this: if you are running 1.5 MAC of volatile, 2mg q30 minutes versed and a propofol drip...what are you going to do if your BIS reads 65? At that point a BIS might actually hurt you. I think you have to use one in this case, but probably should tailor the anesthetic a little more to the actual number. And if you are going to give that much BZD, the rest is probably a moot point.

 

[Idiopathic]

.

 

[BLADEMDA]

My point was this: if you are running 1.5 MAC of volatile, 2mg q30 minutes versed and a propofol drip...what are you going to do if your BIS reads 65? At that point a BIS might actually hurt you. I think you have to use one in this case, but probably should tailor the anesthetic a little more to the actual number. And if you are going to give that much BZD, the rest is probably a moot point.

Has this ever happened to you? How many cases have you done giving all those drugs plus vapor with a BIS reading of 65 or more? This is where you show your inexperience. After tons of PUMP cases where the BIS really IS all over the place the patient ALWAYS responds to drugs and the BIS always falls (after a few seconds) of giving the medication (except for perhaps ketamine).

I use BIS on cardiac and do my best to keep the reading below 60. When it hits 70 I get concerned and treat it. Every BIS responds to midazolam, vapor and/or propofol. If the BIS didn't decrease I would re-check the disposable head piece and confirm adequate adhesion.

Let me know after you have done a few hundred more BIS cases about your experience with the device. Then, your comments may have more than theory behind them.

Blade

 

[cubs3canes]

1st

She brought the records from her previous case to the preop center. It showed a des of 6 or higher in the case. this was at another institution at which the patient worked. She was NOT crazy. She was a great patient that was genuinally concerned. I told her I would do my best, but not at the expense of her hemodynamics. She understood that her risk of awareness was higher. We did not use muscle relaxants after intubation because
that wanted to explore the facial and lingual nerve for the case.

2nd

BIS is just another tool. I used it in this lady and felt good about the depth of anesthesia for her. I am telling you that I would turn off the propofol and the BIS would go to 50. Remember that 50 is still below 60 which is the level at which most people would not have awareness. I also gave her way to much versed 11mg in 2 hours.

3rd
I am still in my CA-1 year. I use this forum to learn about different techniques and difficult cases. I enjoyed this discussion.

Cubs

 

[cubs3canes]

Not a red head. But I find that stuff to be true. (in my limited red head experience)

 

[BLADEMDA]

1st

She brought the records from her previous case to the preop center. It showed a des of 6 or higher in the case. this was at another institution at which the patient worked. She was NOT crazy. She was a great patient that was genuinally concerned. I told her I would do my best, but not at the expense of her hemodynamics. She understood that her risk of awareness was higher. We did not use muscle relaxants after intubation because
that wanted to explore the facial and lingual nerve for the case.

2nd

BIS is just another tool. I used it in this lady and felt good about the depth of anesthesia for her. I am telling you that I would turn off the propofol and the BIS would go to 50. Remember that 50 is still below 60 which is the level at which most people would not have awareness. I also gave her way to much versed 11mg in 2 hours.

3rd
I am still in my CA-1 year. I use this forum to learn about different techniques and difficult cases. I enjoyed this discussion.

Cubs

Good case and overall, you did an excellent job. The extra midazolam in a young, healthy patient is no big deal. I like the way you handled the case but I would hve used less midazolam and more propofol if needed.

AS for a BIS of 60 on her I would not be comfortable with that reading. SHe is a healthy patient and there is no reason not to buy extra insurance against any chance (no matter how small) of recall. So, 50 would be my MAXIMIUM BIS and I would try for 40.

My Group purchased the FIRST BIS machines on the market. We still have a few. Did you know some ASPECT reps. originally though a BIS of 70 was just fine? It wasn't until a year or two later that the company recommended 60 or lower for surgery. Fortunately, we didn't have any recall on those cases where a higher BIS reading was tolerated.

Blade

 

[Planktonmd]

Good case and overall, you did an excellent job. The extra midazolam in a young, healthy patient is no big deal. I like the way you handled the case but I would hve used less midazolam and more propofol if needed.

AS for a BIS of 60 on her I would not be comfortable with that reading. SHe is a healthy patient and there is no reason not to buy extra insurance against any chance (no matter how small) of recall. So, 50 would be my MAXIMIUM BIS and I would try for 40.

My Group purchased the FIRST BIS machines on the market. We still have a few. Did you know some ASPECT reps. originally though a BIS of 70 was just fine? It wasn't until a year or two later that the company recommended 60 or lower for surgery. Fortunately, we didn't have any recall on those cases where a higher BIS reading was tolerated.

Blade

BIS is very unreliable in the absence of muscle relaxants and every time your EMG activity goes up (the lower bar) your BIS number goes up with it, the funny thing I have seen is that many "providers" are unaware of this simple fact and overdose patients based on muscle activity.
So in my opinion you should put BIS on every patient getting GA because you
don't want to be accused of being "dishonest" on Anderson Cooper 360!
But if you are not using a muscle relaxant try to ignore the BIS number as much as you can and concentrate on giving anesthesia.
One more thing:
Awareness with END TIDAL DESFLURANE OF 6 means some one had buffed the records in my opinion.

 

[Idiopathic]

Has this ever happened to you? How many cases have you done giving all those drugs plus vapor with a BIS reading of 65 or more? This is where you show your inexperience. After tons of PUMP cases where the BIS really IS all over the place the patient ALWAYS responds to drugs and the BIS always falls (after a few seconds) of giving the medication (except for perhaps ketamine).

I use BIS on cardiac and do my best to keep the reading below 60. When it hits 70 I get concerned and treat it. Every BIS responds to midazolam, vapor and/or propofol. If the BIS didn't decrease I would re-check the disposable head piece and confirm adequate adhesion.

Let me know after you have done a few hundred more BIS cases about your experience with the device. Then, your comments may have more than theory behind them.

Blade

So if you can tell me that you have done a case where youve run that much agent, that much sedative and that much midazolam and still had an elevated BIS value...you mean to tell me you would still have treated the number further? Doesnt sound appropriate to me.

Im not talking about cardiac pump cases, as I havent done any and Its a completely different scenario.

So save your vitriol for the CRNAs. Sorry you took my comments so personally.

 

[BLADEMDA]

So if you can tell me that you have done a case where youve run that much agent, that much sedative and that much midazolam and still had an elevated BIS value...you mean to tell me you would still have treated the number further? Doesnt sound appropriate to me.

Im not talking about cardiac pump cases, as I havent done any and Its a completely different scenario.

So save your vitriol for the CRNAs. Sorry you took my comments so personally.

I have no "vitriol" towards you. I was pointing out that in my years of experience with BIS (I used it all the time when it first hit the market) I NEVER had or heard of a single case where the BIS reading didn't go down with more agent and/or midazolam. In fact, I thought we were over sedating our cardiac patients because of BIS with midazolam. But, the number ALWAYS fell with the drug.

In the case described above the use of midazolam and propofol was appropriate. I simply would have given less midazolam and more propofol for a faster wake-up.

I had used the BIS regulary on non-paralyzed patients and with sufficient vapor like SEVO the patients are mildly relaxed. There was a recent peer reviewed study showing SEVO has a mild muscle relaxant effect. The problem arises is when you titrate the SEVO down to a low level with the use of BIS. THen, the patient gets a sudden high level surgical stimulation and the BIS increases dramatically with patient movement.

Over the past 3 years I have cut the use of BIS way back despite the media frenzy about awareness. This way I use a little more vapor and the patients stay deep during the case. But, on Cardiac and severe PVD (stent cases) I still use BIS routinely.

Cubs case shows that sometimes the use of BIS may result in over sedation and the use of significantly more drugs for the case. Was it necessary? THe jury is still out on the answer. But, in today's legal climate a patient like Cubs describes above would get a BIS from me and the EXTRA vapor/drugs.

Blade

 

[hokie]

1st

She brought the records from her previous case to the preop center. It showed a des of 6 or higher in the case. this was at another institution at which the patient worked. She was NOT crazy. She was a great patient that was genuinally concerned. I told her I would do my best, but not at the expense of her hemodynamics. She understood that her risk of awareness was higher. We did not use muscle relaxants after intubation because
that wanted to explore the facial and lingual nerve for the case.

2nd

BIS is just another tool. I used it in this lady and felt good about the depth of anesthesia for her. I am telling you that I would turn off the propofol and the BIS would go to 50. Remember that 50 is still below 60 which is the level at which most people would not have awareness. I also gave her way to much versed 11mg in 2 hours.

3rd
I am still in my CA-1 year. I use this forum to learn about different techniques and difficult cases. I enjoyed this discussion.

Cubs

I can't help but think that the fact that you did not use muscle relaxants was probably much more valuable than the BIS...

 

[cubs3canes]

i watched the emg component the entire case. It was not elevated on most of the BIS spikes. I heard the new monitors will factor the EMG in the BIS.

Cubs

 

[Noyac]

Awareness with END TIDAL DESFLURANE OF 6 means some one had buffed the records in my opinion.

Bingo

 

[2ndyear]

i watched the emg component the entire case. It was not elevated on most of the BIS spikes. I heard the new monitors will factor the EMG in the BIS.

Cubs

You're absolutely right. Check out this study:
http://www.anesthesia-analgesia.org/cgi/content/full/97/2/488
Fully awake neuromuscular block, and the BIS goes down. Yes, fully awake neuromuscular block. Definately a paper worth reading in my mind. This was with old software, however. The BIS algorithm is secret, but some degree of EMG does come into play.

Of note, the algorithm for BIS of 40 and less is pretty simple. You'll notice you have another bar in addition to EMG, the suppression ratio, or the amount of time that the EEG is isoelectric. When the suppression ratio is 40% or more, the BIS number is simply =50-suppression ratio/2. So this is your whole BIS range from 0-30.

 

[BLADEMDA]

This is why BIS does not need to be used routinely. There is NO PROOF that BIS actually decreases awareness. ASPECT has done a great marketing job on this device.

However, BIS can be used selectively on certain subgroups of patients. The newer machines are more reliable and each generation of machine gets better.

Blade

 

[fakin' the funk]

Your opinion is read and understood. But, for qualification purposes how many general anesthetics have you delivered? Are you basing your statements on vast clinical experience or published data?

Forget BIS, you are creeping up on the annoying meter.

Have you heard of ad hominem attacks?

 

[BISof60]

Out of curiosity, how many RESIDENTS use BIS monitor routinely either for all cases or specific types of cases.



Metoprolol decreases BIS numbers?
http://www.anesthesia-analgesia.org/cgi/content/citation/105/2/548

 

[Noyac]

Metoprolol decreases BIS numbers?
http://www.anesthesia-analgesia.org/cgi/content/citation/105/2/548

Thats not surprising.