Patients waking during surgery?

you are right... this topic would probably get more response from the anesthesia forum...

the first issue is that the recent study showing that 1 in 2000 patients experience awareness was founded by the manufacturers of the BIS monitor (a device that makes bispectral wave analysis from simple EEG and uses a nifty software to erase background chatter - ie: bovie, to create an artificial number that gives a sense for awareness --- however the only big problem is that is was mainly developed with propofol and high dose volatile anesthetics in mind).... the study definitely makes a good argument to have a BIS on every patient, whereas most anesthesiologists will tell you it is bull in most scenarios...

the second issue is that the number was an average, and really should be separated out into number of awareness events in perfectly well-controlled elective events versus awareness in trauma. When a patient comes in with a massive pelvic fracture exsanguinating at the rate of 2 liters of blood every 5 minutes (and the surgeons are having difficulty stopping the bleeding and are forced to cross clamp the aorta) most anesthetics will be washed out with the hemorrhage... so in those cases you do what you have to do to keep them alive for the surgeons to save, and hope that awareness isn't an issue (we have various drugs for situations like those, my favorite being a scopolamine IV overdose).

the third issue is how well do patients truly report their awareness correctly... we all know that awareness USED to be a huge issue in the beginning of cardiac anesthesia, because we used to give the patient these monumentally LARGE doses of Fentanyl and paralyze them, and then we realized that fentanyl isn't an amnestic .... awareness is becoming a bigger and bigger issue now because we are using more and more paralytics than we used to (they have become better drugs with shorter half-lives) and thus exposing the patient to the potential problem of paralysis without appropriate amnesia.... But I would say that for the most part it is a rare occurrence....

For the neophyte med students going into surgery and the young surgery residents: PLEASE don't misinterpret a patient moving during surgery as the patient being awake... those are spinal reflexes, that's all. It just means the anesthesia at the spinal cord level is light, which has NO correlation with the level of anesthesia at the cererbrum

Originally posted by Tenesma
we used to give the patient these monumentally LARGE doses of Fentanyl and paralyze them, and then we realized that fentanyl isn't an amnestic

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Naracotics paralyze people ?

And...wouldn't a "LARGE" dose of narcotic place you under at the very least a state of concious sedation, and at the most a state of complete nonarousal?

Help me out here...

Originally posted by Tenesma
PLEASE don't misinterpret a patient moving during surgery as the patient being awake... those are spinal reflexes, that's all. It just means the anesthesia at the spinal cord level is light, which has NO correlation with the level of anesthesia at the cererbrum

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You're freaking me out here a bit. Spinal reflexes? This is reminding me of doctors who used to operate on infants without anesthesia because they 'didn't feel pain', or people who think animals don't feel pain.

A person who localizes pain by forcefully grabbing my ass while I'm cutting into his/her skin isn't exhbiting 'spinal reflex'. What would be the local stimulus to that circuit?

I'm not saying that it causes me concern for their well being after the case. But clearly there are times that patients experience breakthrough pain during cases and - if they are not chemically paralyzed - they respond with movement which is proportionate to their level of sedation. If they are paralyzed, they might just get tachycardic and relatively hypertensive.

If a person is heavily sedated, what is the ONLY stimulus which elicits a response? Pain, of course. The person under anesthetic who thrashes and tenses up is responding to pain. Otherwise, they would just continue to lie there in a blissful state of undisturbed comatose.

womansurg

the emphasis was on the AND... we gave them HUGE doses of Fentanyl AND paralyzed them (with vec/panc/atracurium, etc...)

and you are right that a large dose of narcotic would result in a state of complete nonarousal: it would act as an analgesic, amnestic... it can even create a scenario of areflexia (patient doesn't move with stimulation).... however in the cardiac cases the HUGE doses of narcotics were often not rebolused, and we would just ride the context-sensitive half-life till extubation. The point of awareness in cardiac cases was never at induction, however during the surgery the stimulation can be so intense that the patient's brain would be aroused - most awareness in those cases is usually towards the end the patient would be paralyzed, they would have enough fentanyl to create a large sympathectomy, but not much to interrupt memory formation in the hippocampus... you need intense GABA blockade for that, and narcotics do little on GABA.... the drugs you need for GABA are benzos, propofol, nitrous, volatile anesthetics and in some nightclubs: alcohol


and conscious sedation is not necessarily equivalent to amnesia/lack of awareness - conscious sedation is designed to provide the surgeon or person performing the procedure with as little patient movement/resistance as possible, and that can be done with a bunch of drugs that don't interfere with memory (low doses of ketamine, low doses of benzos, euphoric narcotics)


talking about interesting changes for cardiac surgery is the increasing trend towards extubation at the end of the procedure with a very minimalized balanced anesthetic technique combined with a high thoracic epidural - some cardiac centers are extubating almost all of their straightforward CABG/valves 15 minutes after the last bandage... cool...

I think the poster meant fentanyl AND paralyze them. Perhaps he/she means that just because a person is "snowed" it doesn't necessarily mean they are "unaware".

I'm no anesthesiologist but I have asked myself questions in this regard a time or two when I have used RSI. I can't imagine the horror of being completely paralyzed and only partially sedated/amnestic during an intubation and subsequent life-saving (or not) procedures.

womansurg... you are confusing a few things here.

1) patients don't experience pain when they are anesthetized - pain can only be experienced by an awake cerebrum what patients do experience is a sympathetic outflow due to the release of catecholamines and other chemical messengers. And that sometimes can be very subtle, there have been cases of awareness where the patient describes excruciating pain even though their blood pressure and heart rate were rock solid throughout the case (without receiving hemodynamic altering meds)

2) i agree that infants do feel pain, and i agree that animals with a developed cerebrum feel pain.... does a worm feel pain when it is put on a hook? based on how we understand pain and that it is a complicated interpretation by the cerebrum, the argument would be that the worm doesn't experience pain as it lacks a cerebrum --- but the worm sure does wiggle a lot more as it gets shoved on to that hook.... those are reflexes... based on what we understand of the nervous system

3) i would argue that a patient that bucks or has some involuntary movement at times of hyperstimulation is not experiencing pain, as their cerebrum has been disconnected if you will, and are exhibiting reflex behavior.

4) the patient who grabs your ass.... while I am sure it is meant as a compliment that is a sign of higher cognitive function, and therefore I would argue that the patient is close to or already experiencing pain. the interesting thing is that we manage to cloud the sensorium enough, that most patients don't remember, but i still think that is truly pain.


5) your last point about the ONLY stimulus that warrants a response is PAIN is blatantly untrue and I would ask you to remember your days in biology lab when you decapitated/pithed a frog and exhibited leg withdrawal with foot stimulation... Even brain dead patients who you would agree are technically incapable of experiencing pain, withdraw to stimulation... that isn't PAIN, but a reflex...

Originally posted by Tenesma
1) patients don't experience pain when they are anesthetized

5) your last point about the ONLY stimulus that warrants a response is PAIN is blatantly untrue and I would ask you to remember your days in biology lab when you decapitated/pithed a frog and exhibited leg withdrawal with foot stimulation... Even brain dead patients who you would agree are technically incapable of experiencing pain, withdraw to stimulation... that isn't PAIN, but a reflex...

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I agree that anesthetized animals (people) don't cognitively process pain - as in recognizing and remembering it. However, they are still 'experiencing' it.

The frog's leg will respond to stimulus of a local reflex circuit. In human's, the spinal reflexes of the lower extremities are a looped circuit which is independent of the CNS. So I can elicit spinal responses in the leg of a brain dead person. But I cannot make a brain dead person jump, grab my ass, tense up or try to get up off the table no matter how viciously I hack into his torso - even with NO anesthesia on board. When I'm working in the abdomen of a human, there is no spinal reflex which connects feedback there to his arm. I can't stimulate his abdominal skin and make his hand move toward the stimulus. Yet we see that reaction commonly in patients who are not brain dead, even in patients who are in a deep state of coma. We call it 'localizing pain'.

If I switch from handling soft tissue to burning it with a bovey, and the previously quiet patient now jerks and tenses on the table every time the buzz of my cautery goes off - that patient is experiencing and responding to the pain of their burning tissue.

No, they will not recall it, no they are not psychically injured, no it's not a big deal. I simply say "I think she's getting a little light", you guys push more drugs, and all is well. But you can't convince me - or at least haven't so far - that the stimulus reaction there is not one of reception and reaction to...PAIN.

womansurg... you shouldn't ignore a point i made: if the patient grabs your ass that is a very purposeful movement, and therefore would imply voluntary movement due to higher cortical functioning, and thus would indicate the patient was experiencing pain.

the definition of pain is: an unpleasant sensory and emotional experience associated with actual or potential tissue damage.

Pain is a cortical function by definition... No cortex = No pain.

If i bring up an ex-boyfriends name, that may incite pain because of its emotional meaning to you - you have cortical functioning. If I step on your toe, you will experience pain because of the sensory meaning to you - you have cortical functioning.

When you say: "When I'm working in the abdomen of a human, there is no spinal reflex which connects feedback there to his arm" ... that is an erroneous statement. While that response is not necessarily a 2-neuron arc like we learned in 5th grade, it definitely represents a sub-cortical reflex. Here is an example, if I were strike your back with a whip, your sub-cortical reflex would be to constrict your trapezius muscle and pull your arms back, that is an involuntary movement... There are enough studies showing that even beyond purely somatic afferents there are also visceral afferents (these studies were done on monkeys): sigmoid or rectus damage, at the time of damage (thermal injury) causes increased muscle tone of the psoas, duodenal damage, causes increased muscle tone in the low thoracic spine.

Bucking during surgery: is a sign of a perfectly well working gag-reflex... which is a cranial nerve reflex... not an indication of pain.

Does depth of anesthesia have to do with involuntary movement? absolutely... the deeper the anesthetic the more remarkable the areflexia.... I can anesthetize somebody sooo much that they loose their reflexes due to the concentration of anesthetic at the spinal cord/brainstem/medulla level. Thank God for nature, because the amount of anesthetic required to dissociate cortical functioning from the rest of the brain is far less than that required to create areflexia!!!

here is a brain teaser let's say for the same patient I provide exactly the same amount of narcotic and volatile anesthetic, except in one circumstance NO paralytic and the other SOME paralytic. is the one with involuntary movement experiencing pain and the one who is paralyzed not experiencing pain??? how do you now measure their pain?? (especially if i tell you that not everybody has heart rate or blood pressure changes associated with stimulation)

for the sake of this thread, you have to drop your layman's definition of pain and accept the common medical definition of pain

Originally posted by Tenesma
if the patient grabs your ass that is a very purposeful movement, and therefore would imply voluntary movement due to higher cortical functioning, and thus would indicate the patient was experiencing pain.

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Oh...then...I think you just made my point in this case, at least.

I'm just curious, I don't know the answer...do brain dead people arch their back and pull their arms back if struck with a whip?

Also, when I take cautery to a patient's subcutaneous tissues, and a previously unresponsive patient suddenly tenses up - relaxes when I stop - tenses again when I restart - what word are you using to describe this reaction? This happened for me today during a breast reconstruction case. The anesthesiologist chuckled when I asked about which 'reflex' the patient was exhibiting. He said, "she's in pain, doc. Hold on a minute while I push some more narcs." I mean, is there a sub-q tissue to total-body-tone reflex that I didn't learn about in the fifth grade?

I really don't want to quibble about semantics - that doesn't make a very interesting debate at all. You use the term 'reflex' to describe reactions which I think most physicians refer to as 'pain'. In any case, if I'm ever on your table exhibiting one of these 'reflexes', I'd really appreciate it if you could give me the benefit of the doubt and push a few more analgesics.

brain dead people don't have a functioning brainstem nor do they have any cortical function, so the only reflexes that they can exhibit (not always the case) are true spinal reflexes... so no, they won't arch their back when struck by a whip

the reason you can't quibble about semantics is that there is nothing to quibble about... if you call a reflex pain, then i correct you.... if I call an operation a surgery, you can correct me
each profession has their terminology i guess

and maybe that tensing up your patient was doing was because of cautery close to a nerve bundle? hmmm....

by the way, if you do exhibit reflexes under anesthesia (or as you would call them "pain localization") i don't think narcotics would be the first i would push areflexia (the thing you are looking for me to accomplish so the patient doesn't fidget) has very little to do with analgesia... instead a more appropriate and prompter way of obtaining areflexia would be to deepen the anesthetic with GABA or more volatile, or even quicker just a hit of paralytic...

so don't tell me when to push narcotics and i won't tell you what to do when there is a bleeder...

What about conscious sedation, i.e. Versed? I watched a spinal tap (actually a blood patch) done on my wife under Versed sedation, and she experienced a large amount of pain, while awake, and of course remembered none of it. Would experiences like this predipose an individual to 'phantom' pain or subconscious issues?

Originally posted by Tenesma
brain dead people don't have a functioning brainstem .. so no, they won't arch their back when struck by a whip

and maybe that tensing up your patient was doing was because of cautery close to a nerve bundle? hmmm....

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Well, actually they do maintain medullary brainstem function, which is why the heart continues to beat, BP is maintained, etc. Otherwise they would simply be...dead.

Near a nerve which conducts pain, do you suppose? Or it's that sub-q tissue to total-body-tone reflex circuit. That's one widespread mofo of a circuit - I've seen it occur no matter what portion of the body I operate on. Is this the same nerve-reflex that I'm testing on my comatose brain injured patients when I sharply pinch the skin of their chest to see if they
try to move to avoid the noxious stimulus? Because the term that we use to document that is "responds to pain". Would your anesthesiology critical care providers use different terminology there, I wonder?

Sweetie, you're absolutely right that you far better know the pharmacology of effective anesthesia; there was no intention to comment on your selection of medications. I honestly couldn't be less interested in what drugs you choose - only that the patients I take under my care are safely motionless while I dissect near critical structures, and that they seem stable and in no distress. Certainly, use whatever terminology and whatever pharmacology you like so long as these simple goals are accomplished.

And Tenesma, for the sake of all that is honest and good in this world, please cool it with the absurd passive-aggressive smiley faces, references to fifth grade, and reams of pendantic misinformation. I'm not being condescending to you across an ether screen here. I thought we were simply having a halfway interesting conversation about what is probably an obscure academic point in the first place.

Well, I'll say toMAto and you say toMAHto, and we'll all just call it a day.

I think a non/correlational study is in order here. both womansurg and Tenesma have valid point...i think.

Originally posted by womansurg
I agree that anesthetized animals (people) don't cognitively process pain - as in recognizing and remembering it. However, they are still 'experiencing' it.

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I've been confused about this for forever, and no one can explain it to me.

How is it that you can "experience" pain, but not "recognize" it? What is the difference between the two? If the patient is experiencing it, does that mean they're feeling it or not? And by "feeling" it, I mean the way you or I would "feel" it right now, in a completely conscious, un-altered state (assuming that you are )

womansurg...

I have to tell you that for the most part I always enjoy reading your posts... and there are no intents of passive-aggression here.

BUT, you can't call my reams and reams of pedantic forum scribbling misinformation. EVERYTHING i wrote has been substantiated.

I fear that I have to correct you again... Brain dead people do NOT have a functioning brainstem, as that is part of the criteria of brain death: a non-functional brainstem. The brain dead person will be apneic because of it and will have no cranial nerve reflexes (as those nuclei are all in the brainstem) - however the brain dead person will have a heart beat as that is due to intrinsic cardiac pacing cells (sinus node) and will have a blood pressure regulated by the reflex arcs in his carotid bodies as well as the baroreceptors in the aortic arch, as well as the ANP excreted by atria, as well as the angiotensin-renin system.

And the reason muscles tense up when there is cautery near a nerve bundle is not a reflex... that is direct electrical stimulation of the efferent motor axons leading to muscle contraction. Cautery near a nerve isn't painful as there are no noci-receptors on the axons - just like brain tissue is insensate.

the terminology behind "responding to pain" is incorrect and has fallen into our lingo due to overuse, just like EKG gets written into the chart when it should be ECG. The correct description of the patients reaction is "responding to stimulus".


the whole reason why i even brought up the issue about anesthesia and patients moving, is that I always have a curious medical student/nurse ask me if the patient is awake... I was trying to point out that patient movement under anesthesia has minimal to no correlation with awareness (a key player in wakefulness)

Originally posted by Tenesma
I have to tell you that for the most part I always enjoy reading your posts... and there are no intents of passive-aggression here...

I fear that I have to correct you again...

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Just your own sweet way...sorry I misinterpreted you.

Enjoyed chatting with you.

womansurg

i am sorry if i got all worked up about this... happy thanksgiving.

Originally posted by Teufelhunden
I've been confused about this for forever, and no one can explain it to me.

How is it that you can "experience" pain, but not "recognize" it? What is the difference between the two? If the patient is experiencing it, does that mean they're feeling it or not? And by "feeling" it, I mean the way you or I would "feel" it right now, in a completely conscious, un-altered state (assuming that you are )

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Hey, no biggie...y'all can go ahead and close this thread w/o answering the stupid medical student's question.

No hurt feelings here...I'm used to being ignored by attendings

teufelhunden

pain is a cortical interpretation of nociceptive signals....

if your cortex is working (meaning you are awake, alert, and not anesthetized), anything that stimulate your nociceptive receptors will be interpreted by your brain as pain... you will experience pain, you will fell pain.

if your cortex is not working (death or anesthesia), anything that stimulates your nociceptive receptors will not be noticed by your cortex... and won't be identified as pain. those nociceptive receptors however do have some subcortical and hormonal responses... so if you were anesthetized and i were to cut your leg off, your body may very well respond by releasing catecholamines as you are now driven into a fight or flight response... your blood pressure, heart rate will go up... So your body is reacting to the stimulus, but as you are anesthetized, your body won't be able to interpret those stimuli as pain... And if your brain never inteprets those stimuli, it therefore can never have a recollection of those stimuli...

i hope this answers your question

Originally posted by Idiopathic
What about conscious sedation, i.e. Versed? I watched a spinal tap (actually a blood patch) done on my wife under Versed sedation, and she experienced a large amount of pain, while awake, and of course remembered none of it. Would experiences like this predipose an individual to 'phantom' pain or subconscious issues?

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Anyone?

while versed can provide some sedation with some amnestic properties it is by no means an analgesic...

with the versed you are artificially inhibiting memory formation of the pain... so your question about subconscious or "phantom" pain is a very interesting one!

as a med student on the inpatient VA psych. service i saw some interesting vietnam vets --- who experienced unbelievably horrible emotional and physical pain, and some of those guys spent many years in total denial of what happened in Vietnam - as if their memory formation had been de-activated. Only later, did they start having nightmares, etc... the symptoms of post-traumatic stress disorder. They were total wrecks, partially because of the emotional pain they were experiencing...

so i don't have an answer for you, but since we are on the topic of "phantom" pain, I have something interesting to point out:

children who were born without an arm or a leg, will sometimes experience pain in that missing limb (even though they never had it to begin with)... weird huh?

We have done a lot of reading about the facilitation of the spinal cord and the asociated pain reflex. The argument is that this is the reason why 'phantom' pain exists. As long as you have nerve roots, you can have pain. Also, it begs the question of what if a limb is present early in gestation, but then regresses for some reason later on. Is it as though you lost the limb or never had it to begin with?

Just dropping in to say that I love this thread -- I've learned a ton from it. Thanks!

So why isn't a Diprivan drip just manditory on all patients that don't have any complications with General Anestesia.

Originally posted by Idiopathic
We have done a lot of reading about the facilitation of the spinal cord and the asociated pain reflex. The argument is that this is the reason why 'phantom' pain exists. As long as you have nerve roots, you can have pain. Also, it begs the question of what if a limb is present early in gestation, but then regresses for some reason later on. Is it as though you lost the limb or never had it to begin with?

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Well, don't forget that the cortical region in the post central gyrus still exits for that limb. The lateral pathways may be degenerative, but the cortical region still persist.

I'm sure it happens, but I've never personally seen a case of intraop awareness in over a couple thousand of cases. There is a huge margin of error with GA, and miller and other texts will quote amnestic properties for volatiles at .4 MAC. Add this to induction meds consisting of propofol( or induction agent of choice), opiods and benzo's= one scrambled brain.
Now womansurg...if start operating before the patient is very deep, your or my surgical stimulation can alter the patient's level of anesthesia, and if the patient is not paralyzed, you may get a movement......If your case is short, and you don't want your patient paralyzed, this movement may happen....no big deal....or you can be an ass like many of my colleagues and scream the patient is moving...no ****...... The same is true on awakening.....2 options I've learned.....the patient can either be snowed...and wake 40 minutes after you are done...or be maintained paralyzed....which runs the risk of burning the bridge of not being able to reverse....as pt's start to lighten...don't forget...some of the volatiles can take 40+ minutes to wear off, esopecially some of the fatties....or friends on teh other side of the screen have to try to time this with our closing...tough with interns/residents/attendings and others.....Pt's will begin to move as they come back up through Stage2...they are not awake, but can move violently....if you disagre on this, ask your anesthesia buddy to pull the tube when the patient starts to move......

Many pt's remembr heading into the room, get a little benzo, maybe even some scopo. as they get preoxygenated, i am sure they have some really strange recalls to these moments........in terms of the Bis.......ask the gas passers.............

Originally posted by ICUDOC
Now womansurg...if start operating before the patient is very deep, your or my surgical stimulation can alter the patient's level of anesthesia, and if the patient is not paralyzed, you may get a movement

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My hyperstimulation alter the level of anesthesia? No no, you're not paying attention - the resonse implies NO connection to the level of conciousness. That's been the argument all along. Rather, the patient is demonstrating a 'spinal reflex' and "direct...stimulation of the efferent motor axons leading to muscle contraction." For, as we well know, stimulation of nerves "isn't painful as there are no noci-receptors on the axons..." If you review the examples provided, you can see that we've established that the subutaneous fat is loaded with these efferent motor axons - they are in abdominal adipose tissue, breast adipose tissue...you name it.

Sorry for the frustration. What you state here is simply what I've maintained all along.

It's extremely annoying to try to discuss situations such as you describe, and have someone stubbornly (albiet cheerfully !) reinterpret everything cloaked in an Emperor's new suit of pseudoscience. When I go to lengthen a skin incision in the middle of a case, and a previously motionless patient reacts to the new stimulus of my knife blade on his abdomen by drawing up his knees, pulling his arm off the armboard and raising his head off the table - he is not demonstrating a "well working gag reflex", responding to stimulation of his "efferent motor axons" or any of the rest of that nonsense. He's just not deeply enough anesthetized to prevent response to the acceleration of my unpleasant stimuls. Like you said: no big deal. I clarifed from the beginning that I did not believe the patient to have concious awareness of the stimulus.

Certainly patient's do cough and gag during a case, muscles contract when I apply cautery to them, and there are reflex arcs which respond to appropriate input. But christ - call a spade a spade already.

womansurg - first i wish you a happy thanksgiving and then you come write something silly and then try to make an absurd hint at my posts

1) for a general surgery attending, it should embarass you that you don't know or understand the definition of brain death... and i quote "[brain dead people]...Well, actually they do maintain medullary brainstem function, which is why the heart continues to beat, BP is maintained, etc]" how absurd is that?

2) you systematically ignored the nuances of my post which were targetted at responding to your misguided posts:
- you said "patients experience breakthrough pain as they respond with movement" - I had to point out that anesthetized patients don't experience pain, and their movement therefore is not a controlled response to pain but rather a reflex response
- your limited knowledge of neurology reveals that you have no understanding of sub-cortical reflexes

ie: for example, how come I can overdose somebody on Propofol which is NEITHER a paralytic NOR an analgesic, and they don't move to stimulation??!??!?! hmmm, maybe it is because i have reached the threshold whereby the sodium channels conducting signals along their spinal/sub-cortical arcs are abolished....

3) you try to inject pseudo-humor by mangling up my points and coming up with brainless comments like "Rather, the patient is demonstrating a 'spinal reflex' and "direct...stimulation of the efferent motor axons leading to muscle contraction." For, as we well know, stimulation of nerves "isn't painful as there are no noci-receptors on the axons..." Are all of my new teaching points getting your head confused?

4) your comments are typical of the very few surgeons at my institution who are unable to admit when they are wrong, unable to learn - especially when the lessons are dished out by an anesthesiologist.

Trust me on this, I would feel very silly trying to argue the finer points of diagnosing small bowel obstruction, or management of retroperitoneal abscesses with a general surgeon as I am clearly out of my league of understanding on those subjects... just as you have demonstrated your clear lack of knowledge on the subject of Areflexia, Amnesia, Analgesia and Anesthesia.

So before you call my babblings pseudo-science, why don't you get a neurology textbook:
http://www.harcourt-international.com/catalogue/title.cfm?ISBN=0750674695
and a good anesthesia textbook:http://www.amazon.com/exec/obidos/t...=sr_8_3/103-4320875-7215048?v=glance&n=507846

and then we can talk about science and medicine

in the meanwhile as I stated in a previous post, I hope you have a nice thanksgiving weekend,

Tenesma

I always find catfights so...morbidly fascinating, somehow.

Originally posted by Tenesma
4) your comments are typical of the very few surgeons at my institution who are unable to admit when they are wrong, unable to learn - especially when the lessons are dished out by an anesthesiologist.

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You only have a few of these? I've never me a surgeon who could admit there was something they didn't know. Messes with their god complexes.

Naeblis....

at my institution (MGH) very, very, very few have a GOD complex... most of them are amazing surgeons with great hearts and thirsty minds.

Originally posted by Tenesma
Naeblis....

at my institution (MGH) very, very, very few have a GOD complex... most of them are amazing surgeons with great hearts and thirsty minds.

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Lucky you! Many of the surgeons I had known at med school wouldn't even consider the possibility that there was something they weren't an expert on, and if you ever provided fact to the contrary they would dismiss the subject as simple, unimportant, and beneath them. Hopefully the surgeons where i sart my anesthesia training next year will be better (U of R), I have heard they are, but who knows.

Its good to know that the surgeons at mgh are of a good nature, maybe there is hope for the rest of them.

I was attempting to be professional and not even go near the statement by womansurg about braindeath......but now that I learn she is an attending.......my God, from which fine intsitution might I ask did you graduate from.....I'll make sure never to send my family there.....That is truely a disgrace....Did you never have to declare someone braindead before???? The first braindeath criteria from the President's commission for the study of ethical problems in medicine: Guidelines for the determination of Death, is......ABSENCE OF BRAINSTEM REFLEXES. Don't forget apnea and all the other criteria..... Also, as you widen your incision and have a pt bend their knees, jump out of the bed etc.....Never has this happenned to me. Perhaps a jerk, an attempted breath against the ventillator, but to jump out of bed....give me a break.

Tenesma, this person isnot an attending.....My guess is a 4th yr med student thinking about a career in surgery. Her arguments with you are, for the most part, completely unfounded.......

To jump back to the cortical pain minithread:

There have been instances during DBS where patients w/ various pain syndromes have had thalamic centers stimulated which completely relieved their pain.

This thread is pretty damn informative and hysterical at the same time. Really goes to prove the adage that a surgeon is never in doubt but not always right. Funny how the obvious hardheadedness and idocy of one poster is painfully exposed. Now that poster doesn't have much to say. Everyone is so civil around here. What happened to a good old fashioned flame war? Call a spade a spade.

I was reading along, you obviously all know way more than me, a lowely ms1 but I had a question in response to this, "will have a blood pressure regulated by the reflex arcs in his carotid bodies as well as the baroreceptors in the aortic arch, as well as the ANP excreted by atria, as well as the angiotensin-renin system" aren't those blood pressure arcs going to the vasomotorcenter which is spread along the rostral and caudal ventrolateral medulla. My understanding of the pathway is this. Afferent CN 9 and 10 from the aortic arches and carotid bodies carry information to the sensory area (nucleus tractus solitarius) which send output signals to the dorsal motor nucleus and the nucleus ambigus for reflex control of the heart. The Nucleus tractus solitarius i thought also projects to the vasodilator area (ventrolateralrcaudal medulla) which then can inhibit the vasoconstricter area(ventrolateralrostral medulla). I guess my confusion is this, would a brain dead person have the baroreceptor reflex intact?

Thanks in advance,
Zedpol

p.s. please not this is not an inflammatory post, just curious if i have something screwed up.

zedpole... very good question

everything you said is right... as brain death develops it moves rostrally to caudally, and the carotid/aortic arch reflexes are usually the last to go since they are truly at the most caudad point of the nucleus/tractus solitarius in the inferior olive of the medulla oblongata... but it does happen that the most caudad sections remain untouched by brain death, so that patients will preserve those reflex arcs despite brain death.... there is an excellent review in the New England Journal of Medicine Vol. 344 No. 16 (moer specifically middle of page 1216.)

so bottomline most brain dead would lose their vagally/glossopharyngeally mediated baroreceptors but some retain them, and in those who lose those baroreceptors, their blood pressure will still be mediated by starling's curve, angio-tensin, ANP, etc...

Thanks for the clarification, this stuff is just straight up neat.

Zedpol

Hey people very stimulating thread, I am always for discussion coz you always learn something from it even when people end up looking like****, I do not want and I am not in a position to take sides. I just have a question, something about something I did not follow quite well; Tenesma has stated in a previous post that "Pain is a cortical function by definition... No cortex = No pain." Well my question is: what about the thalamus, so far the discussion has been focusing or cortical VS spinal reflexes, I am just wondering about the role of the thalamus in this as it is the relay for pain fibers before going to the cortex. My question is: in a patient whose cortex is completely off (i.e. anesthetized) does the thalamus become off too? And if it does not , is it possible that it " Perceives" pain and I mean really experience pain , which is another thing than associating it with its emotional ' cortical " content, if all this sequence of thought turns out to be true then I guess the above cited definition of pain wont be totally true. I wonder also whether the so called "thalamic-pain" is a misnomer as it is actually perceived through the cortex.
One more thing, what if it is not the thalamus, I mean I totally agree with Tenesma that it is NOT the spinal cord or brain stem but there is much to the subcortex than that ?aint there any studies showing that there are other SUBCORTICAL centers but (still supraspinal ) that " PERCIEVE" pain, perhaps not the same quality of cortical pain but still perception. I have just remembered a paragraph in William F. Gannong Review of medical physiology 17th edition, chapter 7 and I guess it supports my view.. it is titled" sub cortical perception and affect" here it goes without any editing
"There is considerable evidence that sensory stimuli are perceived in the absence of the cerebral cortex and this is especially true of pain. The cortical receiving areas are apparently concerned with the discriminative, exact and meaningful interpretation of pain and some of its emotional components, but perception alone DOES NOT REQUIRE THE CORTEX"
I would really appreciate your input. And for all the nice people here, I am not an attending, not a resident just a final year foreign medical student and this not intended to rekindle any fires; I am just curious and a bit confused ?thanks.

you hit on something here... threecoins...

you are absolutely right that pain pathways go through the thalamus, and in fact there is an entity known as "central pain syndrome" which used to be called "thalamic stroke pain syndrome" - people who have their thalamus injured (primarily by stroke, but other causes exist) experience this and it is a horrible thing to have (and difficult to treat). it is not a misnomer at it is the epicenter for the signals going out to the cortex which are interpreted as pain.

under anesthesia, pretty much the whole brain gets turned off to some extent or another --- depending on the depth of anesthesia more or less tracts will be fully functional.... light anesthesia will basically suppress cortical functioning and hippocampal memory etc, and leave subcortical/spinal reflex arcs intact... the deeper the anesthesia, the more tracts get suppressed. so it is difficult to know to what extent the thalamus gets turned off - at my institution we are in the process of doing a lot of Functional Imaging under Anesthesia where you can see which parts of the brain are on and off, so more information will come soon (some hints of info were described by some of my attendings a few months ago in the New England Journal of Medicine).

the ganong you are referring to is the 17th edition (written in 1993 and published in 1995) - and represents somewhat of a mis-statement and has since been removed from more recent editions.... there is sub-cortical perception of stimulation which will usually result in a catecholaminergic response which we see as tachycardia and hypertension, (basically increased sympathetic outflow)... As pain becomes a better understood field/discipline (it is still very poorly understood) definitions change - and as it stands know, pain is believed to be a purely cortical function/interpretation of signals.

a better resource for understanding pain would be the
Mass General Hospital of Pain management (available at amazon.com)....

Thanks Tenesma, I gotta a few thoughts I wanna share with you here:
1- If we adopt the view that pain is "purely cortical" then the thalamic pain term sounds very confusing even if we regard that it is a relay station for pain signals before they reach the cortex, the same applies for many other sub cortical structures that serve as precortical relays, if we apply this definition should not we have entities called " spinal pain" , " cerebellar pain" etc ? see my point?
2- Is it absolutely confirmed that the subcortical structures are concerned ONLY with autonomic responses but NO perception , aint there any evidence ( even controversial ) that pain is perceived even partly in a some sub cortical structures.
3- I was thinking about this, other sensory modalities get perceived in some areas and then get interpreted by others, we have many lesions that affect interpretation but spare perception i.e. the patient who has visual agnosia actually sees the stimulus but does not know its meaning, why cant a mechanism like this be present, i.e some sort of pain agnosia where a patient experiences pain BUT does not interpret it? the definition you cited of pain makes pain very unique among other sensations identifying it as the same thing as the cortical interpretation it elicits ?" pain IS an unpleasant sensory and emotional experience" rather than pain is a sensation WITH unpleasant sensory and emotional experience components... if pain is like most other sensations then it probably gets perceived somewhere ( probably sub cortically) then have its meaning interpreted in areas in the cortex. Again if this train of thought is logical then it could be possible that pain is perceived in patients under light anesthesia (where some subcortical structures are not OFF yet like u said) but its meaning is NOT interpreted or registered in memory i.e. some sort of pain agnosia but STILL there is pain...would be glad to know what you think, thanks.

Where is womensurg?

i was wondering the same thing. as a rule she's not one to back down, but i haven't seen her backed into a corner quite like this before. maybe she'll just admit she was wrong on the brain death thing and move on, lol.

threecoins

you bring up some very interesting points about pain... since i have some time off, i will have to do a bit more reading... but interesting points.

tenesma

thanks tenesma I will certainly take that as a compliment

just wondering if you have done any follow-up to this:

"at my institution we are in the process of doing a lot of Functional Imaging under Anesthesia where you can see which parts of the brain are on and off, so more information will come soon"

if so, thanks for any input.

dfk said:

just wondering if you have done any follow-up to this:

"at my institution we are in the process of doing a lot of Functional Imaging under Anesthesia where you can see which parts of the brain are on and off, so more information will come soon"

if so, thanks for any input.

Click to expand...

PM Tenesma...he is an attending anesthesiologist, probably doesn't check this forum anymore but he still posts in Gas Forums.