Did anyone else see the show on Anesthesia Awareness on Discovery Health tonight?

[Roland]

It started by offering several case histories of individuals who experienced this horrifying phenominum estimated to affect 40,000 people in the United States each year. One lady was alert as her eye was pulled from her head (she suffered from coneal erosion syndrome which can cause extreme eye discomfort). Another women wrote a book entitled Silenced Screams after her experience of awake alertness during an operation.

One of the expert featured on the program, Dr. Peter Sebel of Emory University indicated that often there are no overt indications when this rare phenominum occurs. Dr. Sebel indicated that studies have shown that in many cases of anesthesia awareness there were no detectable physiological clues that this was occuring. What is more even when the hypnotic and analgesic agents fail, the paralytic agents seem not to and to prevent the person from in any way signaling their plight. What is perhaps worse even when clues to increased alertness are detected, the additional paralytic agents rather than additional anesthesia are often administered which may not solve the problem. He indicated that sometimes these anesthesia failures may be due to genetic resistence to agents like fentanyl, errors made during pre-opt evaluation, or equipment malfunctions. However, in some cases he indicated that we just don't know what the etiological basis for these anesthesia failure are.

Dr. Paul Miles of Melbourne University is working on a machine which may provide a solution. The BIS anesthesia machine (bi-spectral analysis machine?) add EMG and EEG brain wave data to traditional telemetry elements such as blood pressure, heart rate, breathing rate ect. The theory is that even if blood pressure and heart rate do not indicate increased conciousness, that brain waves patterns are likely to be altered. The BIS then integrates all of this information (including brain wave data) via an algorithm into a NUMBER that reflects the relative level of conciousness. One hundred equates to maximal, awake, alertness, while a zero would equate to a profoundly deep coma. Most patients are maintained in the forty to sixty range. One patient featured undergoing surgery with the BIS machine to monitor anesthesia displayed increased awareness after the first surgeons cut. Dr. Miles indicated that due to the information provided by the BIS that he administered additional analgesics, rather than increased paralytics, as would have been the case were he lacking the extra information provided by the BIS. IF trials prove effective then this technology might make possible precisely adjusting anesthesia dosages to achieve optimal levels of conciousness, and more importantly to prevent "anesthesia awareness".

In addition, it occured to me that active monitoring of brain activity might prove even more effective in accurately judging conciousness. If technologies such as PET scanning could be employed (active PET scans are already being investigated to improve the effectiveness of certain anti cancer therapies such as radio frequency ablation of hepatic cancer) then the brain could be monitored in real time. Certain areas of the brain such as the anterior, cingulate gyrus are almost invariably more active with increasing conciousness and would signal anesthesia failure. Of course there would be issues such as cost, and perhaps physiological conflicts between the dyes used for such scans, and the requirements of surgery.

Is this a subject that is frequently addressed among CRNA's? If so what are some other alternatives that are considered to minimize the chances of this sort of horrific experience?

[Tenesma]

all the most recent studies regarding depth of anesthesia as far as awareness and mortality rates have been sponsored by Aspect Medical (the manufacturer of the BIS monitor)... so the news they are putting out there (which the media loves because it is scary and increases ratings) is a bit over embellished.

1) awareness is very infrequent in the general population - the numbers that they used include Trauma and Obstetric numbers (which are always going to make the numbers look falsely elevated)

2) BIS only uses 2 different brainwaves: 3 and 4 Hz - it doesn't take into account blood pressure, heart rate or anything else - the newer BIS has a software algorithm to try to eliminate electro-cautery interference. And has only been shown to be effective in the setting of propofol/barbiturates/volatile anesthetics... A BIS is useless if you are doing a nitrous narcotic technique, or if you are using ketamine.

3) in fact some of the reticular activating formation that is responsible for a large part of the waves that is picked up, can send some false information.... for example, if somebody is paralyzed and therefore there is diminshed afferent input to the reticular activating formation then you will have a lower BIS.

4) i have used the BIS a lot - and there have been times where the number reads 40 (which according to the literature suggests unconsciousness) and the patien is talking to me - or vice-versa a number of 98 and the patient doesn't arouse for 15 minutes.

I think there are certain situations where the BIS may be helpful: ie, a AAA with epidural running, full paralysis and just a touch of volatile - that way you may feel a bit more comfortable running very low volatile to fuzz their memory.

It is not a bad tool - but it is not the hoped-for depth-of-anesthesia-monitor that we all pray for every day.... in fact, these TV specials are giving the patients too much information: a few weeks ago during a pre-op for a crani a patient was very distressed that we wouldn't be using a BIS monitor - 1) it was a nitrous narcotic technique 2) the sensing pads would be in the surgeons field.... and you know how patients believe everything they see on TV

[nilepoc]

As an experiment, I did my 9 MAC cases last thursday, with the BIS. I was in the GI suite, and wanted to see what the BIS would show in the setting of MAC anesthesia.

Well for one thing, according to the BIS readings I was actually practicing general anesthesia on most of my cases that day. I had variable results in that the numbers would tell me that the patient should be entirely out, but they were sitting there watching the tour of their colon, with detatched disinterest. (this only happened in one case, on a woman who warned me before hand that she was very difficult to do MAC anesthesia on, and had had bad experiences in the past with her colonoscopies) After her case, I asked her what she remembered, and she stated that she remmebered nothing, and told me it was the best anesthetic for a colonoscopy she had ever had. Meanwhile, the BIS said that she should have been completely out.

My technique for the day, was Propofol push for every case, with no other adjuncts. No patient claimed to have remembered anything.

I can say that the BIS is a pain in the ass, and requires more fidling than getting a diffficult IV stick. I found it to be not worth the time, and that I could get consistent results without it.

I am not sure how it will fit in to my practice yet, but I am trying to see if I find it useful.

[deepz]

This TV coverage lately has drawn a lot of attention to the incidence of recall, claimed to 40,00 / yr in the USA.

http://www.anesthesiaawareness.com/

is run by Carol Weihrer, the unfortunate individual who suffered the enucleation with full recall and then apparently launched a personal crusade. (Who could blame her?) Months ago I wrote to ask Carol Weihrer where the number 40K came from. I have received no answer from her.

deepz

[alansmith52]

this word mac.. I do not think it means what i think it means.

remember i am still new into the didactic part.

one day we learned that mac stood for maximal aveolar concentration or somthing like that.

another day. in pharm the instuctor started speaking some gibrish about doing "local mac" cases. durring colonsopies. so i am trying to figure out in my mind what avleolar concentraion has to do with with a procedure that to my knowledge takes a little versed.

And best I can tell there might be one or two more definitions for the same acranym. he he he.

since weve been learing about this stuff. Nilepoc have you ever tried ketamine for those local mac cases.. is it to much? I hear some facilities havn't embraced the re-kindeling of the ketamine use. we read a study in wich a small does of ketamine was used with the propofol to offset the hemodyamic repercusions of the propofol and to run the prop to the end of the case until the elim half time of ketamine passes so there is no emergence delirium.

I dont know anything about this. can anyone elaborate.

[NCgirl]

Yeah, MAC stands for two things. Not fair is it, for us newbies? Anyhow, it is one---Minimal Alveolar Concentration. This pertains to inhalational agents, and it's the concentration at 1 atm that prevents skeletal muscle movement in response to maximal pain stimulus (incision) in 50% of pts. There are lots of MAC's in relation to this, such as MAC awake, which is usually said to be .33 of MAC. Anyhow, I won't get too into that, you'll learn more than you ever wanted to know when you get to the inhalational agents. MAC, number 2, is ---Monitored Anesthesia Care. This is what nilepoc was talking about. These are the type of cases you'll see in places like GI lab and Cath lab. It's simply a type of anesthesia, just like "general" or "regional". Hope this helped!

[Roland]

I don't think that the public can have too much information it is unfortunate that Discovery Health doesn't seem to have supplied a "fair and balanced" view of the issue. At the very least they should have provided a dissenting opinion concerning the extent, and confounding variables involved with "anesthesia awareness". This is especially unfortunate given that Discovery Health is usually an excellent venue for health information.

[deepz]

Originally posted by Roland

I don't think that the public can have too much information ............This is especially unfortunate given that Discovery Health is usually an excellent venue for health information.

Actually, Roland, in my estimation the public CAN have too much information on occasion. What we tell patients and family must be tailored to the individual, to their level of education and understanding, etc., just as our anesthetic plans are individualized to meet a specific person's needs. Medical information without some of the scientific background needed to grasp broader implications might just as well be witchcraft mumbo-jumbo.

This is the root fallacy of running medical malpractice trials through the kangaroo court of 'a jury of our peers.' Laymen cannot generally be 'peers' to highly educated professionals, because they cannot render fair verdicts with a laymen's grasp of the underlying principles.

And stories like the sensationalistic 40,000 cases of awareness and recall only frighten the public unneccesarily.

It's all about the eyeballs for Discovery Channel and the other media making money from the number of people who watch the commercials: more sensational stories, more eyeballs, more advertising dollars. Sorry to be so cynical.

deepz

[Roland]

are easily corrected with MORE information (if they are misconceptions). For instance, they should have said that the 40,000 number might reflect inflation from trauma, and pregnancy situations if that is the case. The Professor from Emory University could have cited the studies (or the producer could have referenced) that show that there are indeed cases of anesthesia awareness that are not detectable by conventional modalities.

I don't believe that the public should trust elites without question. However, neither should they pursue witchhunts based upon incomplete or potentially misleading information. Most people who care can comprehend the information IF it is adequately presented.

[deepz]

........Most people who care can comprehend the information IF it is adequately presented.

Out there in the real world, Roland, you would find a lot of patients who will insist you NOT tell them about potential side effects and complications. If you don't want to know, don't ask -- something like that. You're always tailoring your approach to the individual patient. And for a provider to force-feed unwanted information to a patient, well, that's just paternalistic grandstanding, in my estimation.

40,000 is a ** figure. You see no documentation because it is a ** figure. As I've said before, I wrote the anesthesiaawareness.com lady and asked her where the figure originated. No answer.

deepz

[Kason]

I heard her speak in a VANA meeting. That dumb MDA was chemically unfit (for lack of better words) to work that day.

[Roland]

Out there in the real world, Roland, you would find a lot of patients who will insist you NOT tell them about potential side effects and complications. If you don't want to know, don't ask -- something like that. You're always tailoring your approach to the individual patient. And for a provider to force-feed unwanted information to a patient, well, that's just paternalistic grandstanding, in my estimation.

40,000 is a ** figure. You see no documentation because it is a ** figure. As I've said before, I wrote the anesthesiaawareness.com lady and asked her where the figure originated. No answer.

deepz

than to the situation of a specific patient. For example, I think more shows such as the one presented by Discovery Health would be a good thing. However, I think it is of critical importance that when controversies exist, that both sides be given "fair and balanced" treatment.