Rouser was right?

[Rolfe]

Remember this thread? (http://forums.randi.org/showthread.php?s=&threadid=46424)

Rouser was dementing on about "avoiding modern medicine's temple of doom" because of the risk of anaesthetic awareness. This was generally agreed to be a rare phenomenon.Originally posted by TruthSeeker
It is a very rare thing but it does happen. Estimated prevalence is about .02% of general anaesthesia inductions. There was a recent case series linking it to the development of post-traumatic stress disorder.There was a programme about this on Channel 4 last night, in which the figure agreed by the researchers was in fact 0.1% of inductions, or 0.2% of inductions if you counted everyone who had "some awareness" during anaesthesia.

This is quite a lot of people.

They interviewed some of the victims (including one woman to whom it had happened twice, both times with the same anaesthetist), and they were indeed severely traumatised. However, I wasn't entirely clear that all the 0.1% had the very clear memories of the people interviewed. (And they did also point out that some people who were obviously "aware" during anaesthesia didn't count because they didn't remember the awareness afterwards, so the figures weren't entirely crystal-clear.)

Nevertheless, the problem was obviously common enough to be worrying, and for several support groups for victims to be set up and so on. So, I was wondering if the people here who know about these matters would care to give their opinions? I know TrushSeeker and ThirdTwin have some expertise for a start.

The reason I find it intriguing is that vets don't use this type of anaesthesia at all. We use a system where the same agent provides both the unconsciousness and the muscle relaxation, so that any patient getting light enough to become aware will also start struggling and moaning - I suspect before they're really conscious.

One human anaesthetist on the C4 programme stated that it was his primary duty to keep his patients alive so that if necessary they could complain to him later about any awareness they might have suffered. Implication being that the risk of awareness is the price paid for the level of anaesthetic safety enjoyed.

So, is the propofol/isofluorane system used by vets (assuming I've got that right, last time I was giving anaesthetics it was thiopentone/halothane) so much more dangerous in terms of anaesthetic deaths that the possibility of 0.1% awareness is a justifiable trade-off?

And if it is, anybody (John Bentley? Badly Shaved Monkey?) know why the human system with the curare-type drugs isn't used in veterinary surgery? (At least the dogs and cats wouldn't be able to sue, and in fact I suspect that their memories work in such a way that they wouldn't suffer the same degree of trauma anyway.)

Rolfe.

[CurtC]

I should have a weighty opinion on this, because it happened to me. Fortunately for me, I was aware for a short time (maybe 30 seconds?), but felt no discomfort. If the painful kind happens that frequently, the medical profession does need to address it.

[Soapy Sam]

Ask me again in April.:(

I would be interested to know if people to whom this happens have other conscious / unconscious boundary oddities- lucid dreams, sleepwalking, sleep paralysis.

[CurtC]

No, no, and no for me.

[BillHoyt]

Originally posted by Soapy Sam
Ask me again in April.:(

I would be interested to know if people to whom this happens have other conscious / unconscious boundary oddities- lucid dreams, sleepwalking, sleep paralysis.

I take it you're about to have surgery? And you're not too happy about the prospect? Don't blame you at all; it is always a frightening prospect. Want to talk about it?

[TruthSeeker]

I had some post-traumatic stress reviewing that thread!

The prevalence of intraop awareness is inconsistent across studies due to differences in measurement and researchers corroborating the memory to actual events.

The .2% rate you cite is likely from this study:
Awareness during anaesthesia: a prospective case study


Source
Lancet. 355(9205):707-11, 2000 Feb 26.

Abstract
BACKGROUND: Patients who are given general anaesthesia are not guaranteed to remain unconscious during surgery. Knowledge about the effectiveness of current protective measures is scarce, as is our understanding of patients' responses to this complication. We did a prospective case study to assess conscious awareness during anaesthesia. METHODS: 11785 patients who had undergone general anaesthesia were interviewed for awareness on three occasions: before they left the post-anaesthesia care unit, and 1-3 days and 7-14 days after the operation. FINDINGS: We identified 18 cases of awareness and one case of inadvertent muscle blockade that had occurred before unconsciousness. Incidence of awareness was 0.18% in cases in which neuromuscular blocking drugs were used, and 0.10% in the absence of such drugs. 17 cases of awareness were identified at the final interview, but no more than 11 would have been detected if an interview had been done only when the patients left the post-anaesthesia care unit. ....
.

There were a large number of responses to this study. You'll note that the rate of immediate recall was .09% (11/11785) but this rose to .18% after three interviews. So, does it take time to remember or to create (false?) memories? Difficult to say.

Another study recruited people who reported awareness and found:

Conscious awareness during general anaesthesia: patients' perceptions, emotions, cognition and reactions.

Source
British Journal of Anaesthesia. 80(2):133-9, 1998 Feb.

Abstract
We interviewed 45 patients, who answered advertisements (n = 21) or were referred by colleagues (n = 24), about their experience of intraoperative awareness using a standardized questionnaire. Auditory perceptions, hearing sounds or voices were mentioned by all patients (45 of 45): 33 of 45 patients understood and recalled conversations; 21 of 45 patients had visual perceptions; 12 of 21 recognized things or faces; 29 of 45 patients felt being touched; three patients had the sensation of moderate pain; and eight patients were in severe pain. Patients' feelings were mostly related to paralysis (27 of 45), helplessness (28 of 45), anxiety and fear (22 of 45); 18 were in severe panic. All patients (45 of 45) recognized the situation as a real event: 22 of 45 patients experienced unpleasant after effects; 11 suffered from anxiety and nightmares; and three developed post-traumatic stress disorder syndrome and required medical treatment. Twenty of 45 patients were especially attentive to emotionally relevant remarks on their own person, their disease and the course of their operation. The accuracy of sensory perception indicates a very high level of cognitive performance of patients during intraoperative awareness.QUOTE]

However, the authors did not verify the accuracy of the recall nor have any evidence regarding premorbid psychological distress. I have no doubt that true intraoperative awareness can lead to PTSD but as we said in the other thread, many people have either inaccurate recall (dream?) or awareness only as they come out of the GA so it isn't as traumatic.

Here's a case study of patients whose memories were corroborated:


[QUOTE]Pain flashbacks in posttraumatic stress disorder.

Source
Clinical Journal of Pain. 20(2):83-7, 2004 Mar-Apr.
Abstract
OBJECTIVES: Surgical patients who regain consciousness while under general anesthesia may develop symptoms of Posttraumatic Stress Disorder (PTSD). One common PTSD symptom is the experiencing of abnormal perceptions during which the patient feels as if the trauma is recurring. The objective of this report is to document the re-occurrence of pain as part of the PTSD sequelae. RESULTS: We present two patients who developed PTSD following an episode of awareness under anesthesia. In both cases, posttraumatic sequelae persisted for years and included pain symptoms that resembled, in quality and location, pain experienced during surgery. In addition to their similarity to the original pain, these pain symptoms were triggered by stimuli associated with the traumatic situation, suggesting that they were flashbacks to the episode of awareness under anesthesia. DISCUSSION: The similarity between the patients' pain symptoms and pain experienced during trauma, the triggering by traumatic cues, and the associated emotional arousal and avoidance suggest the involvement of a somatosensory memory mechanism.

.

I won't comment on your drug questions as I am not an anesthetist.

In summary, it is a rare occurence which can be accompanied by significant psychological distress and morbidity.

[John Bentley]

Hey Rolfe,

Wow, 2 times in one year where a topic is right up my alley. I'm having tremors from the excitement!

Part of the training from my Master's in Small Animal Surgery required me to train under a Board Certified Veterinary Anethesiologist, so I can answer from both the academic standpoint and the practitioner POV.

To answer your question, veterinarians in Universities regularly use curare type muscle relaxants, especially with intrathoracic surgery (you can imagine the difficulty of heart surgery when you can't control the breathing). Also, it is fairly routine to use it in large animal medicine, especially with equines.
Large veterinary facilities in private practice who have well trained anesthetic assistants use it on a fairly regular basis, although less than in a University setting.
It is almost never used in small animal medicine in routine private practice (at least where I am located) because the monitoring necessary to use it safely makes it impractical.

Of course, it is impossible to know whether an animal is aware during surgery unless it is hooked up to an EEG. (This has been done, and is the reason why vets use isoflurane rather than enflurane. The Enflurane was causing seizure activity in the brain of anesthetized animals).

As an aside, although isoflurane has become the standard gas for vets, it is mainly for the safety of anesthetists, rather than the animal. Halothane, which is a far superior anesthetic in animals in my opinion, was causing problems with the techs and doctors because breathing the very small amts coming from the dog after surgery was leading to kidney and liver problems from constant exposure to free halogen molecules.

Also, propofol reeks as an anesthetic for animals, and is far inferior to other types of injectable anesthetics for animals. I remember when it became all the rage for boarded vet anesthesiologists to tout its wonderful properties. I personally believe it was mainly because they had what I call "real doctor envy". It was being used in human medicine so vets wanted to shoehorn it into vet protocols, whether or not it fit or made sense.

[Rolfe]

Thanks very much for that, John. I remember being taught about the muscle relaxant techniques at college, but I've never used them. I can imagine that having to rely on a trainee nurse to monitor an anaesthetic rather than having a consultant anaesthetist does cramp the style somewhat.

I'm still curious though as to whether the curare-type methods are inherently so much safer than the halothane/isofluorane methods that the risk of awareness during anaesthesia is so much worth taking.Originally posted by TruthSeeker
The prevalence of intraop awareness is inconsistent across studies due to differences in measurement and researchers corroborating the memory to actual events.I can't say exactly what the TV programme was talking about, because the "expert" being interviewed simply stated that it was generally agreed by those who'd researched the matter that the awareness rate was 0.1%, or 0.2% if you counted everyone who had reported "some" awareness. However, that still left a number of questions unanswered, most importantly whether everyone in the 0.1% group had such clear and distressing awareness as the people interviewed for the programme (all of whom were taking legal action against the hospitals concerned).

One of the interviews related to what sounded like a clear case of negligence, in that it was stated that the cylinder of anaesthetic gas being used was empty. Another patient had had it happen to her twice, both times with the same anaesthetist, but a third (intervening) anaesthetic with a different anaesthetist had resulted in no problems, which does rather raise the question of possible individual bad practice. Awareness due to a definnite mistake is clearly a different matter from an incident where everything was done right but the patient had an idiosyncratic response.

(Where's Rouser, anyway?)

Rolfe.

[Badly Shaved Monkey]

Just to add to John Bentley's answer, I remember answering boldly and confidently in my final viva a question from Kathy Clarke about monitoring anaesthesia with the use of muscle relaxants that it was not really much harder than without them because many of your cues to anaesthetic depth are intact.

Oh, the bravery of youth and inexperience!

In the real world, with a single nurse who is also getting out instruments for you you do not have the degree and quality of monitoring that is routine in human surgery (at 10 to 100 times the price of course!)

[Rolfe]

Originally posted by Badly Shaved Monkey
I remember answering boldly and confidently in my final viva a question from Kathy Clarke about monitoring anaesthesia with the use of muscle relaxants that it was not really much harder than without them because many of your cues to anaesthetic depth are intact.If we're getting into true confessions of examination gaffes, I'm the one who told Lindsay Mackie (or was it Bill Jarrett? - they were playing good cop/bad cop on me at the time, with Lindsay as bad cop) that there was no connection between albumin synthesis and the liver! Never mind, I've done my share of grilling on the young entry since then, and had a chance to retaliate....

I'd still like to know why the human medics choose to use the muscle relaxants in spite of the risks of awareness. There must be someone who has the comparative mortality stats somewhere!

Rolfe.

[Dr. Imago]

As I am soon about to enter training as an anesthesiologist and having taken several peri-operative electives already to date, I supposed I should chime in... ;)

I'm very skeptical about the sudden prevalence of reports in the lay media about this phenomenon. Over the past several months, there have been repeated stories in the news about awareness.

It is understandable why this is a scary phenomenon, but I object to the scare tactics used by such reports which instill fear in patients about to undergo surgery - something that is already scary enough.

I'm skeptical because there is a relatively new monitoring device, called the BIS monitor, that is on the market now. Although this technology is on the market, it is still not widely used - especially in routine cases. What these news reports become is a de facto direct-to-patient marketing tool in order to get hospitals and anesthesia groups to invest in this technology on a wider scale even when it may not be necessary.

I have seen the BIS used in cases where tight control of the anesthesia is required, like in spinal cases where the patient cannot be taken too deep in the anesthestic because of the necessity of EMG monitoring during the procedure. In such cases, you are much more likely to have an "awareness" phenomenon.

Likewise, the majority of awareness cases occur during emergence from the anesthetic, especially when the patient is waking-up and is still intubated. To me, this is not "true" awareness as this is a normal part of the case. It can be frightening for the patient because, based on the setting, he/she may have the sensation that they are suffocating. But, in actuality, there is no real danger to the patient. Most often, there is still enough anesthestic on board to prevent memory of the event. But, for some people, this is so unnerving and traumatic for them that they are able to recall this despite having amnestic drugs on board.

I think anesthesiologists need to do a better job of explaining to the patient before hand what may or may not occur during the case. The best anesthesiologists I have seen so far will discuss what might happen during the case and they pre-emptively tell the patient to just relax and know that it is normal and that they are still being taken care of.

Incidences where the patient is paralyzed and fully aware of what is going on during the procedure are best attributed to human error (such as the anesthesiologist forgetting to turn on the vapor or the vapor cannister being empty, etc.). This is inexcusable, of course, but such instances are extremely rare.

I'm not sold yet on the BIS monitor, which has its own inherent limitations. Certainly, it can add to the cost of the case and it is an extra device that needs to be monitored that can potentially distract the anesthetist from other things to do in the case. Still, there may be a role in some particular surgeries, such as neuro cases.

All in all, awareness is a relatively rare phenomenon that can be attributed often to normal events during the peri-operative period. In the numerous cases where I was directly involved in caring for the patient (i.e., inducing them, intubating them, running the case, emerging them, etc.) I always asked if they remembered anything. To date, I only had one younger female (who was highly discriminating and very nervous prior to the procedure) say afterwards that she felt like she was having a "bad dream" and that "something had gone wrong" during the procedure. She was a bit of a rocky emergence in that she really bucked the respirator and tried to sit up on the surgical table while she was still intubated. I didn't run this case, but I attributed her remembrance of these events to the fact that it was a short case and she was emerged very rapidly.

Would I categorize this as "awareness"? Not in the sense that I think these news reports are getting at.

The point is, it is scary that you are going into surgery and are going to let someone take over control of you - both the anesthesiologist and the surgeon. You are going to come out of that room surgically changed. Not to diminish the impact of true awareness during the procedure, the point is that patients will remember some things during the peri-operative period. We do our best to keep people amnestic and out of pain. I think that true awareness (i.e., the sensation of being cut into and having organs painfully tugged at) is truly rare. Better communication of how the case will run prior to giving anesthesia is an area that anesthesiologists can do better - and certainly a lesson I have learned and will relay to my patients.

-TT

[TruthSeeker]

Very well said, TT.

I was at an anesthesia research conference yesterday and similar views were expressed about BIS.

As for awareness, the preliminary results of a large, multisite, prospective study were presented. In this very careful thoughtful study, rate of awareness during the procedure (not during awakening) was 1:2000 (.05%). These data are not yet published as the study continues so make of them what you will.

[CurtC]

Originally posted by ThirdTwin
I have seen the BIS used in cases where tight control of the anesthesia is required, like in spinal cases where the patient cannot be taken too deep in the anesthestic because of the necessity of EMG monitoring during the procedure. In such cases, you are much more likely to have an "awareness" phenomenon.That's interesting to me, because my surgery (in which I became aware) was to fix a broken neck, and to cut into the dura mater to do a "decompression" to help with an Arnold-Chiari malformation. Would this require EMG monitoring, even if they're not supposed to be going into the core of the spine, but just into the dura?

[Dr. Imago]

Originally posted by CurtC
That's interesting to me, because my surgery (in which I became aware) was to fix a broken neck, and to cut into the dura mater to do a "decompression" to help with an Arnold-Chiari malformation. Would this require EMG monitoring, even if they're not supposed to be going into the core of the spine, but just into the dura?

I don't know off the top of my head, Curt, because I haven't yet seen such a case. Although I have seen several laminectomies, in which case the anesthesia has to be kept "light" in order not to interfere. I would imagine, still, that because they are in and around the spinal column - especially in the cervical region - that there probably would be EMG used, and that your anesthesia was kept light. Worst case scenario is that a nerve root is accidenally cut during the procedure and you end up with a permanent disability from the surgery. Evoked EMG is the best way monitor for this during the actual procedure, and unfortunately deep anesthesia and paralysis affects this.

Either way, you should have been told about this before the procedure (at least I would have). Some people like a lot of details, others don't. You have to gauge how much information is too much information for some patients. But, I've found so far that patients will tell you when you're giving them too much info... which is rarely the case.

-TT