From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med
Subject: Re: diprovan
Date: 12 Feb 1999 07:50:28 GMT

In <19990210162055.27503.00000081@ng153.aol.com> kriggs125@aol.com
(Kriggs125) writes:

>this is being posted on several medical ng.
>
>
>What training does a nurse need (R.N.) to administer diprovan for
>conscious sedation?



   I dunno, but it ought to be a hellava lot.  It's an anaesthetic, and
a powerful and tricky one (known in the trades as "milk of amnesia,
because it's disolved in basically Intralipid, it crosses the blood
brain barrier to produce unconsciouness in seconds, much like a
barbiturate).  A nurse anaesthetist, or possibly an ICU nurse with a
patient already on a ventilator, ought to be the only ones allowed to
touch the stuff.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med
Subject: Re: General Anaesthesia
Date: 28 May 1999 13:35:39 GMT

In <7ilql1$d9d$1@pegasus.csx.cam.ac.uk> "Bennett" <njb35@spam.ac.uk>
writes:

>clw@teleport.com wrote in message ...
>>In article <374DAA98.21803FB7@nospam.sympatico.ca>, happydog@sympatico.ca
>>wrote:
>>
>>> Do people intentionally kept unconscious after, say, a head injury
>>> count? That can go on for days.
>>
>>
>>No. That is trauma, not anesthesia. Anesthesia is much more controlled
>>than just lying in a coma in an ICU.
>
>
>Not necessarily - many are kept purposefully anaesthetised, especially in
>cases of head trauma. Movements (especially coughing) raise intercranial
>pressure, and by decreasing brain activity you decrease blood flow, which
>can also be a significant factor in increased ICP. The skull's not
>flexible, and they try to keep it as empty as possible. I've even seen
>one example where a young lad had a partial lobotomy to reduce ICP...
>Poor kid was only about 10 or so - RTA. No idea how he did, since I was
>posted elsewhere for a few weeks, and didn't see him or his parents when
>I came back.
>
>Cheers
>
>Bennett


   Or they "pop your top," which is to say temporarily remove the front
of your skull and bone bank it, to give your brain room to swell
acutely.

    Most promising new strategy is to keep head injured or brain
ischemically injured people at 90 F for a couple of days.  This has the
same effect on the brain as putting ice on your ankle after spraining
it. Rest, ice, NO compression, elevation. Not RICE, but RINE is the
brain-sprain protocol.

From: jrfox@no.spam.fastlane.net.no.spam (Jonathan R. Fox)
Newsgroups: sci.med
Subject: Re: General Anaesthesia
Date: Sat, 29 May 1999 04:18:04 GMT

On Fri, 28 May 1999 16:45:03 -0700, clw@teleport.com wrote:

>In article
><906441FCAE627BF1.BD51EB01C504428B.7070E2C4930A304E@library-proxy.airnews.net>,
>jrfox@no.spam.fastlane.net.no.spam (Jonathan R. Fox) wrote:
>
>> On Thu, 27 May 1999 17:07:37 -0700, clw@teleport.com wrote:
>>
>> >In article <374DAA98.21803FB7@nospam.sympatico.ca>,
>> >happydog@sympatico.ca wrote:
>> >
>> >> Do people intentionally kept unconscious after, say, a head injury
>> >> count? That can go on for days.
>> >
>> >No.  That is trauma, not anesthesia.  Anesthesia is much more controlled
>> >than just lying in a coma in an ICU.
>>
>> No, sometimes people are intentionally kept under general anesthesia,
>> such as in a pentobarbital coma, when recovering from a serious brain
>> injury.
>>
>> --
>> Jonathan R. Fox, M.D.
>
>You are talking about sedation and paralysis, not anesthesia.  The use of
>Phenobarbital (as opposed to pentabarbital) for cerebral protection (along
>with several other modalities, hypothermia, perhaps steroids, mannitol,
>hyperventilation to CO2 around 20 torr etc) is adjuvant, but this is not
>"anesthesia".  There is no "pain control" with this manuever.

No, I am talking about general anesthesia, which was the original
question.  You are correct that "anesthesia" literally means "no
feeling," which would imply analgesia, and that pentobarbital is not
primarily an analgesic, but the term "general anesthesia" is in
reference to a state of analgesia, amnesia, loss of consciousness, and
sometimes loss of reflexes and paralysis which are induced by various
agents.  Barbiturates are perfectly capable of inducing general
anesthesia, and in fact, I believe thiopental was the first
intravenous general anesthetic.

The original question was about duration of general anesthesia for
operations.  This is stage III anesthesia, which is surgical
anesthesia.  In a pentobarbital coma (we use pentobarb at our
institution, not phenobarb), the goal is Stage IV, or coma.  Since
this is actually deeper (how often to you wheel an EEG to the bedside
during an operation to make sure you're flattening brainwaves, like
you do when inducing a pentobarb coma?), I would submit that this
certainly does "count" towards the original question, as Happy Dog
asked.

In response to the original question, I have seen a child recently who
had his face reconstructed after being severely injured by a dog, in
which he was under general anesthesia for over two days.  Of course,
kids tolerate everything better, so I don't know if you would expect
an adult to last that long!

--
Jonathan R. Fox, M.D.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med
Subject: Re: General Anaesthesia
Date: 31 May 1999 21:57:38 GMT

In
<6D31CC7EA82D5B5A.DF83B2DEDDE54F14.A26FE23AB1A8A285@library-proxy.airne
s.net> jrfox@no.spam.fastlane.net.no.spam (Jonathan R. Fox) writes:

>That was my point.  EEG is not used for surgical anesthesia.  It is
>sometimes used when going into deeper central nervous system
>depression than surgical anesthesia, such as in a pentobarbital coma.
>Both are stages of general anesthesia.
>
>I also agree that the stages of anesthesia are mostly irrelevant now
>that, for surgical operations, we use presedation and rapidly absorbed
>inhaled anesthetics that act faster than old ones like diethyl ether,
>so that you don't see the progression from Stage I to III.  But the
>stages do exist, and we do look for the distinction between III and IV
>when inducing pentobarb coma, whereas this is not routinely done in
>the operating room.
>
>--
>Jonathan R. Fox, M.D.


    EEG is most certainly used for surgical anaesthesia, and will be
used in the future probably as standard of care, though in a somewhat
less recognizable form that in the past.  Today's units put one
electrode complex on the forehead, look at the power spectrum and
convert the spectral edge frequency (the frequency below which 95% of
the spectral power is present) to a simple 10 to 100 sedation number.
The lower it is, the more your patient's neural activity has been shut
off, and the deeper he is into coma.  Below a given number there is
virtually no possibility he is conscious, which removes the possibility
he will wake up and report hearing things during the opperation, and
feeling pain which he could do nothing about since paralyzed with
neuromuscular blocking agent (still very common in abdominal surgery
and some others).  All of which is surprising common, as you know, and
which the best of anaesthesiologists had a hard time guaranteeing will
not happen.  The savings in lawsuits from use of such devices has
caused Ceders Sinai in LA to just purchase one for *every* O.R., and
they are about $20,000 each.   Several EEG power spectral edge units
have been on the market before this, but they've been bulky, cranky,
complex, subject to muscle artifact, showed data the average person
doesn't need, and were hard to interpret with a lot of training.  Worst
still, they've been aimed at ICU sedation, which was the wrong market
financially.  All are now gone, but the "idiot's delight" unit which
shows just the one number and has no CRT, is gaining rapidly.  Think of
it as pulse-ox for the brain.

  Which is not to say they might not be quite useful for monitoring
pentobarb coma.  Which itself is rapidly becoming obsolete.  Dr. Fox,
if your institution has a choice, you should seriously consider using
the old "truth serum" drug thiopental ("Sodium Pentothal" or
Thionembutal) for that purpose.  It's just as safe and there's just as
much experience with it.  The duration of action is much the same by
the time you get the CNS loaded (the short action of thiopental is all
from initial redistribution, a distinction which disappears with longer
term use).  The advantage to thiopental is that in animal models it's a
vastly superior CNS injury protector compared to equipotent brain
sedating doses of Nembutal/pentobarbital.  Turns out the antioxidant
effect of the free thiol (-SH) group which you get after body
buffering, and only difference in the molecules, is even more important
than the barbiturate brain metabolism lowering effect.  Who would've
thunk it?

                                     Steve


                                       Steve Harris, M.D.

From: jrfox@no.spam.fastlane.net.no.spam (Jonathan R. Fox)
Newsgroups: sci.med
Subject: Re: General Anaesthesia
Date: Tue, 01 Jun 1999 09:18:55 GMT

On 31 May 1999 21:57:38 GMT, sbharris@ix.netcom.com(Steven B. Harris)
wrote:

>    EEG is most certainly used for surgical anaesthesia, and will be
>used in the future probably as standard of care, though in a somewhat
>less recognizable form that in the past.  Today's units put one
>electrode complex on the forehead, look at the power spectrum and
>convert the spectral edge frequency (the frequency below which 95% of
>the spectral power is present) to a simple 10 to 100 sedation number.
>The lower it is, the more your patient's neural activity has been shut
>off, and the deeper he is into coma.  Below a given number there is
>virtually no possibility he is conscious, which removes the possibility
>he will wake up and report hearing things during the opperation, and
>feeling pain which he could do nothing about since paralyzed with
>neuromuscular blocking agent (still very common in abdominal surgery
>and some others).  All of which is surprising common, as you know, and
>which the best of anaesthesiologists had a hard time guaranteeing will
>not happen.  The savings in lawsuits from use of such devices has
>caused Ceders Sinai in LA to just purchase one for *every* O.R., and
>they are about $20,000 each.   Several EEG power spectral edge units
>have been on the market before this, but they've been bulky, cranky,
>complex, subject to muscle artifact, showed data the average person
>doesn't need, and were hard to interpret with a lot of training.  Worst
>still, they've been aimed at ICU sedation, which was the wrong market
>financially.  All are now gone, but the "idiot's delight" unit which
>shows just the one number and has no CRT, is gaining rapidly.  Think of
>it as pulse-ox for the brain.

I had indeed heard about the device you mention, which is why I should
have said that EEG is not _routinely_ used for surgical anesthesia.
Perhaps it will be soon.

One problem with medical devices that are "dumbed" up for anyone to
use is that the dumbing process causes its own problems.  The pulse-ox
is the perfect example, as anyone who has been called hurriedly by a
rookie to the bedside of a patient who is "desating" when he actually
just wiggled his toe while playing Nintendo can attest.  I wonder if
misinterpretation of a simplification of otherwise complex data will
lead to inappropriate anesthetic maneuvers without evaluation of other
more useful paramaters, the way people react to a pulse-ox reading
without looking at the patient.

--
Jonathan R. Fox, M.D.